PL187539B1

Ductile coat coated hard powders and sinters made of such powders

Abstract

The present invention relates to a sintered material comprising a plurality of core particles, consisting of diamond or cubic boron nitride or one or more first metal compounds, wherein the or each first metal compound consists of a metal compound selected from the group consisting of: niobium carbide, tantalum nitride, TiN, TiCN, TiB2, TiC, ZrC, ZrN, VC, VN, Al2O3, Si3N4 and AlN; an intermediate layer on each of the core particles, the intermediate layer consisting of a second metal compound, wherein the second metal compound consists of WC or W2C, thereby forming coated particles; and a binder overlaying the intermediate layer on the coated particles and constituting a layer including iron, cobalt, nickel, their mixtures, their alloys or their intermetallic compounds.

PL187539B1, drawing sheet 1 — Sheet 1 of 8

Term

Term ended

Expired 13 May 2018, 8.4 years ago.

41 claims: 7 independent, 34 dependent

1
Zastrzeżenia patentowe 1. Materiał spieczony, zawierający liczne cząstki rdzeniowe, znamienny tym, że cząstki rdzeniowe składają się zasadniczo z pierwszego związku metalu mającego formułę MaXb, gdzie M stanowi metal wybrany z grupy składającej się z tytanu, cyrkonu, hafnu, wanadu, niobu, tantalu, chromu, molibdenu, wolframu, glinu i krzemu, X stanowi jeden lub więcej pierwiastków wybranych z grupy składającej się z azotu, węgla, boru i tlenu, zaś a i b stanowią liczby większe niż zero do i włącznie z liczbą cztery, warstwę pośrednią na każdej z tych cząstek rdzeniowych, która to warstwa składa się zasadniczo z drugiego związku metalu, odmiennego pod względem kompozycji od pierwszego związku metalu i mającego większą względną odporność na pękanie, który to drugi związek metalu nadaje się do wiązania z pierwszym związkiem metalu i nadaje się do wiązania z metalem wybranym z grupy składającej się z żelaza, kobaltu i niklu, tym samym tworząc cząstki powlekane, oraz spoiwo pokrywające tę warstwę pośrednią na cząstkach powlekanych, która to warstwa zewnętrzna zawiera żelazo, kobalt, nikiel, ich mieszaniny, ich stopy lub ich związki międzymetaliczne.
2
Materiał spieczony według zastrz. 1, znamienny tym, że powleczone cząstki mają przeciętny rozmiar mniejszy niż około 2000 nm.
3
Materiał spieczony według zastrz. 1, znamienny tym, że powleczone cząstki mają przeciętny rozmiar mniejszy niż około 1000 nm.
4
Materiał spieczony według zastrz. 1, znamienny tym, że warstwa pośrednia ma grubość po spieczeniu w zakresie od 5% do 25% średnicy cząstek rdzeniowych.
5
Materiał spieczony według zastrz. 1, znamienny tym, że warstwa pośrednia ma taką grubość, że obszary naprężeń towarzyszące dyslokacjom w jednej powleczonej cząstce są przekazywane poprzez tę warstwę pośrednią do bezpośrednio sąsiadującej cząstki rdzeniowej.
6
Materiał spieczony według zastrz. 1, znamienny tym, że warstwa pośrednia ma grubość po spieczeniu w zakresie od 3% do 200% średnicy cząstek rdzeniowych.
7
Materiał spieczony według zastrz. 1, znamienny tym, że warstwa zewnętrzna ma grubość po spieczeniu w zakresie od 3% do 12% średnicy cząstek rdzeniowych.
8
Materiał spieczony według zastrz. 1, znamienny tym, że warstwa zewnętrzna ma taką grubość że obszary naprężeń towarzyszące dyslokacjom w jednej powleczonej cząstce są przekazywane przez spoiwo do bezpośrednio sąsiadującej warstwy pośredniej.
9
Materiał spieczony według zastrz. 1, znamienny tym, że pierwszy związek metalu składa się zasadniczo ze związku stechiometrycznego.
10
Materiał spieczony według zastrz. 1, znamienny tym, że pierwszy związek metalu składa się zasadniczo ze związku metalu wybranego z grupy składającej się TiN, TiCN, TiB2, TiC, ZrC, ZrN, VC, VN, A-C-, S13N4 i A1N.
11
Materiał spieczony według zastrz. 1, znamienny tym, że drugi związek metalu składa się zasadniczo ze związku metalu wybranego z grupy składającej się z WC i W2C.
12
Materiał spieczony według zastrz. 1, znamienny tym, że części warstwy pośredniej i spoiwa są usunięte dla odsłonięcia wnętrza cząstek rdzeniowych.
13
Materiał spieczony według zastrz. 1, znamienny tym, że ma on odporność na pękanie większą niż sześcienny azotek boru.
14
Materiał spieczony, zawierający liczne cząstki rdzeniowe, znamienny tym, że cząstki rdzeniowe składają się zasadniczo ze związku metalu wybranego z grupy składającej się z TiN, TiCN, TiB2, TiC, ZrC, ZrN, VC, VN, AI2O3, Si3N4 i A1N, warstwę pośrednią na każdej z cząstek rdzeniowych, która to warstwa składa się zasadniczo z drugiego związku metalu, odmiennego pod względem kompozycji od pierwszego związku metalu i mającego większą względną odporność na pękanie, który to drugi związek metalu składa się zasadniczo z WC, 187 539 i spoiwa pokrywającego tę warstwę pośrednią na powleczonych cząstkach, które to spoiwo zawiera kobalt lub nikiel.
15
Materiał spieczony, zawierający liczne cząstki rdzeniowe, znamienny tym, że cząstki rdzeniowe składają się zasadniczo z licznych związków metalu, każdy mający formułę M a Xb, gdzie M stanowi metal wybrany z grupy składającej się z tytanu, cyrkonu, hafnu, wanadu, niobu, tantalu, chromu, molibdenu, wolframu, glinu i krzemu, X stanowi jeden lub więcej pierwiastków wybranych z grupy składającej się z azotu, węgla, boru i tlenu, zaś a i b stanowią liczby większe niż zero do i włącznie z liczbą cztery, warstwę pośrednią na każdej z tych cząstek rdzeniowych, która to warstwa składa się w zasadzie z odmiennego związku metalu, odmiennego pod względem kompozycji od tych licznych związków metalu tworzących cząstki rdzeniowe i mającego większą względną odporność na pękanie, który to odmienny związek metalu nadaje się do wiązania ze związkami metalu tworzącymi cząstki rdzeniowe i nadaje się do wiązania z metalem wybranym z grupy składającej się z żelaza, kobaltu i niklu, tym samym tworząc powleczone cząstki, i spoiwo pokrywające tę warstwę pośrednią na powleczonych cząstkach, które to spoiwo zawiera żelazo, kobalt, nikiel, ich mieszaniny, ich stopy lub związki międzymetaliczne.
16
Materiał spieczony według zastrz. 15, znamienny tym, że powleczone cząstki mają średni rozmiar mniejszy niż około 2000 nm.
17
Materiał spieczony według zastrz. 15, znamienny tym, że powleczone cząstki mają średni rozmiar mniejszy niż około 1 nm.
18
Materiał spieczony według zastrz. 15, znamienny tym, że warstwa pośrednia ma grubość po spieczeniu w zakresie od 5% do 25% średnicy cząstek rdzeniowych.
19
Materiał spieczony według zastrz. 15, znamienny tym, że warstwa pośrednia ma taką grubość, że obszary naprężeń towarzyszące dyslokacjom w jednej powleczonej cząstce są przekazywane przez tę warstwę pośrednią do bezpośrednio sąsiadującej cząstki rdzeniowej.
20
Materiał spieczony według zastrz. 15, znamienny tym, że warstwa pośrednia ma grubość po spieczeniu w zakresie od 3% do 200% średnicy cząstek rdzeniowych.
21
Materiał spieczony według zastrz. 15, znamienny tym, że warstwa zewnętrzna ma taką grubość, że obszary naprężeń towarzyszące dyslokacjom w jednej powleczonej cząstce są przekazywane przez warstwę zewnętrzną do bezpośrednio sąsiadującej warstwy pośredniej.
22
Materiał spieczony według zastrz. 15, znamienny tym, że związki metalu tworzące cząstki rdzeniowe stanowią zasadniczo związki stechiometryczne.
23
Materiał spieczony według zastrz. 15, znamienny tym, że związki metalu tworzące cząstki rdzeniowe składają się zasadniczo ze związków metalu wybranych z grupy składającej się z TiN, TiCN, TiB 2 , TiC, ZrC, ZrN, VC, VN, A1 2 O 3 , Si 3 N 4 i A1N.
24
Materiał spieczony według zastrz. 15, znamienny tym, że ten odmienny związek metalu stanowi zasadniczo WC.
25
Materiał spieczony według zastrz. 15, znamienny tym, że części warstwy pośredniej i spoiwa są usunięte dla odsłonięcia wnętrza cząstek rdzeniowych.
26
Materiał spieczony według zastrz. 15, znamienny tym, że ten materiał spieczony ma odporność na pękanie większą niż sześcienny azotek boru.
27
Materiał spieczony, zawierający liczne cząstki rdzeniowe, znamienny tym, że cząstki rdzeniowe składają się zasadniczo z sześciennego azotku boru, z warstwy pośredniej na każdej z tych cząstek rdzeniowych, która to warstwa składa się zasadniczo z WC, przy czym ta warstwa pośrednia ma grubość po spieczeniu w zakresie od 5% do 25% średnicy cząstek rdzeniowych, i spoiwo zawierające żelazo, kobalt, nikiel, ich mieszaniny, ich stopy lub związki międzymetaliczne przykrywające warstwę pośrednią, przy czym to spoiwo ma grubość po spieczeniu w zakresie od 3% do 12% średnicy powleczonych cząstek, przy czym kombinacja cząstek rdzeniowych, warstwy pośredniej i spoiwa tworzy powleczoną cząstkę.
28
Materiał spieczony według zastrz. 27, znamienny tym, że powleczone cząstki mają przeciętny rozmiar mniejszy niż około 1000 nm.
29
Materiał spieczony zawierający liczne cząstki rdzeniowe, znamienny tym, że cząstki rdzeniowe składają się zasadniczo z diamentu i/lub sześciennego azotku boru z warstwy pośredniej na każdej z cząstek rdzeniowych, która to warstwa składa się zasadniczo ze związku 187 539 metalu mającego większą większa odporność względną na pękanie niż cząstki rdzeniowe oraz spoiwo zawierające żelazo, kobalt, nikiel, ich mieszaniny, ich stopy lub ich związki międzymetaliczne, przy czym warstwa pośrednia ma grubość po spieczeniu w zakresie od 5% do 25% średnicy cząstek rdzeniowych, kombinacje cząstek rdzeniowych, warstwy wewnętrznej i spoiwa kształtującego powleczone cząstki.
30
Proszek składający się zasadniczo z licznych powleczonych cząstek, znamienny tym, że główna część tych powleczonych cząstek zawiera cząstki rdzeniowe składające się zasadniczo z pierwszego związku metalu mającego formułę MaXb, gdzie M stanowi metal wybrany z grupy składającej się z tytanu, cyrkonu, hafnu, wanadu, niobu, tantalu, chromu, molibdenu, wolframu, glinu i krzemu, X stanowi jeden lub więcej pierwiastków wybranych z grupy składającej się z azotu, węgla, boru i tlenu, zaś a i b stanowią liczby większe niż zero do i włącznie z liczbą cztery, oraz warstwę na każdej z tych cząstek rdzeniowych, która to warstwa składa się zasadniczo z drugiego związku metalu, odmiennego pod względem kompozycji od pierwszego związku metalu i mającego większą względną odporność na pękanie, który to drugi związek metalu ma zdolność wiązania z pierwszym związkiem metalu i ma zdolność wiązania z metalem wybranym z grupy składającej się z żelaza, kobaltu i niklu.
31
Proszek według zastrz. 30, znamienny tym, że powleczone cząstki mają średni rozmiar mniejszy niż około 2000 nm.
32
Proszek według zastrz. 30, znamienny tym, że powleczone cząstki mają średni rozmiar mniejszy niż około 1000 nm.
33
Proszek według zastrz. 30, znamienny tym, że warstwa ma grubość w zakresie od 5% do 25% średnicy cząstek rdzeniowych.
34
Proszek według zastrz. 30, znamienny tym, że warstwa pośrednia ma grubość po spieczeniu w zakresie od 3% do 200% średnicy cząstek rdzeniowych.
35
Proszek według zastrz. 30, znamienny tym, że pierwszy związek metalu składa się zasadniczo ze związku stechiometrycznego.
36
Proszek według zastrz. 30, znamienny tym, że pierwszy związek metalu składa się zasadniczo ze związku metalu wybranego z grupy składającej się z TiN, TiCN, T1B2, TiC, ZrC, ZrN, VC, VN, AhCty S13N4 i A1N.
37
Proszek według zastrz. 30, znamienny tym, że drugi związek metalu składa się zasadniczo z WC lub W2C.
38
Proszek według zastrz. 30, znamienny tym, że zawiera zewnętrzną warstwę spoiwa składającą się zasadniczo z metalu wybranego z grupy składającej się z żelaza, kobaltu, niklu, ich mieszanin, ich stopów, lub ich związków międzymetalicznych, przy czym ta warstwa spoiwa jest osadzona na zewnętrznej powierzchni warstwy drugiego związku metalu w postaci warstwy ciągłej.
39
Proszek według zastrz. 38, znamienny tym, że ciągła warstwa spoiwa jest osadzona poprzez chemiczne osadzanie oparów, rozpylanie katodowe, osadzanie karbonylowe, bezprądowe platerowanie przez natryskiwanie roztworu, elektroplaterowanie lub fizyczne osadzanie oparów.
40
Proszek składający się zasadniczo z licznych powleczonych cząstek, znamienny tym, że zawiera liczne cząstki rdzeniowe składające się zasadniczo z sześciennego azotku boru, z warstwy pośredniej na każdej z cząstek rdzeniowych, która to warstwa składa się zasadniczo z WC, przy czym ta warstwa pośrednia ma grubość po spieczeniu w zakresie od 5% do 25% średnicy cząstek rdzeniowych, i warstwę zewnętrzną zawierającą kobalt lub nikiel, przykrywającą tę warstwę pośrednią, przy czym kombinacja cząstek rdzeniowych, warstwy pośredniej i warstwy zewnętrznej tworzy proszek.
41
Proszek według zastrz. 40, znamienny tym, że cząstki stanowiące ten proszek mają średni rozmiar mniejszy niż około 1000 nm. 187 539

Independent claims41

155 paragraphs in 5 sections, as filed

The present invention relates to a sintered material comprising a plurality of core particles and a powder consisting essentially of numerous coated particles. Such materials find particular use as metal forming members, such as cutting and metal forming tools.

In the mid-thirties, tool steel alloys began to be replaced by tools from sintered tungsten carbide powder, which quickly became standard tools due to their excellent hardness and intrinsic high firmness and shear strength. The hardness of such materials improved the tool life, while the compactness and strength resulted in increased performance by allowing the use of larger loads, speeds and more aggressive forging parameters. The development of cemented carbide tools and their industrial availability increased significantly after the Second World War.

However, even such materials are subject to wear, and the mechanism of such wear is not fully explained. Progressive wear causes changes in the shaping of the material, and as a result of the need to maintain dimensional tolerances of the parts, the tool must be replaced when it is no longer suitable for producing parts with the correct size. The time or number of parts manufactured before such wear clearly indicates the cut-off time of the tool. The resulting loss of performance during tool change and process re-setting, mismatched production, restarting and missing rules were the reasons to try to find materials that would ensure longer tool life.

The tool life is determined by its resistance to several types of wear, its response to significant loads and impacts. In general, the higher the chip removal rate (high loads and speeds), the drawing and forming pressures, and the longer the tool geometry is maintained, the better the tool is rated. Better cutting and forming tools must be simultaneously hard, tough, stiff and resistant to chipping, cracking, thermal degradation, fatigue, chemical reactions with the workpiece and wear through abrasion. Thus, the dominant desirable mechanical properties of the sintered tool are strength, hardness, high modulus of elasticity, resistance to brittle fracture, low chemical interaction with the workpiece and low friction coefficient to assist in forming the workpiece while reducing heat buildup.

In the current years, the powder metallurgy industry has grown significantly due to the ability of powders to flow cold into a precise form. This allows the mold to be reused, often with a large volume, and significantly reduces machining, molding and other process steps because the sintered part is very close to its intended configuration, or "close to clean shape." Such parts, more and more commonly produced today mainly from aluminum, iron and copper powders, require some of the same desirable features as tools. For this reason, many products obtained by powder metallurgy are subject to additional forging, plating or heat treatment to achieve local hardness, firmness and strength. Many of these parts require the characteristics of impact and abrasion resistance, which are the same mechanical properties as those desired for tools.

In tools and hard products, wear resistance increases at the expense of strength, and currently the best tools show the best compromise between these characteristics and are therefore limited to use in special cases.

In addition to tungsten carbide, it has also been found that a variety of alloys, coating technologies, and combinations of these agents not only increase tool life, but also increase cutting speed and charge feed. Powder metallurgy and sintering led to the development and production of new materials with increased hardness and firmness, and the addition of a hard coating for sintered alloy by chemical vapor deposition (CVD), physical vapor deposition (PVD) or plasma-assisted chemical vapor deposition (PACVD) increased resistance to wear.

To date, many preparations have been made for the production of powder coatings for coating substrates and other hard material reinforcing agents. The prior art regarding tool materials lists six phenomena that are currently known

187 539 and generally used to provide this type of improved wear resistance and firmness, each with significant benefits and significant disadvantages: (1) mixing hard and ductile particles, (2) chemical vapor deposition (or other) coating sintered substrates with layers in the hard phase, (3) combining the first and second processes, (4) ceramic-metal sinters (cermet), (5) for a special type of tool (grinding and sanding media), chemical bonding of low concentrations of large diamond particles or cBN in a hard but relatively weak abrasive substrate, and (6) Functional Gradient Materials (FGM).

None of these solutions have brought about a fundamental combination of the desired tool properties, and only chemical vapor deposition (CVD or PVD) is currently used for some mechanical parts requiring increased abrasion resistance.

Mixed hard and ductile ternary systems

Despite many auxiliary treatments and modifications existing and envisaged in the prior art, mixing of hard WC-TiN-Co spot particles with carbide powder before sintering has several disadvantages. Because these harder particles have low mutual solubility relative to the binder, the lateral strength of the substrate drops quickly above 6-10% by weight of the hard particles. Thus, surface hardness and wear resistance are also reduced compared to surface coating. The wear mechanism is also not significantly improved because a small amount of hard particles (less than 1 in 10 at the surface) bind poorly to the binder and fall off completely.

Chemical vapor deposition (CVD) coatings

Such hard outer coatings of hard intermetallic and cermet layers on tool steels or sintered substrates (after sintering) are valuable because they provide high surface hardness, usually showing values of 2400 Vickers (TiN) to 5000 Vickers (cubic boron nitride) to 9000 (diamond). For all ancillary treatments, changes and sintering aids that exist and are disclosed in the prior art, including additional coating layers, locally changed substrate structures, and admixtures or grain size reduction coatings, the outer coating solution has several major disadvantages, including coating detachment and cracking during use (resulting from different amounts of thermal expansion of the coating and substrate, as well as from bending and surface loads) and desirable high CVD process temperatures (900 ° C-1200 ° C), which may not be consistent with the needed heat treatment for strength or geometry of the sintered part.

The conventional CvD coating of already sintered products with several different coatings or layers allows to withstand two or three special operating conditions. However, since each layer must be applied in succession, one or two other special coatings must remain covered until the outer layers are worn. Therefore, only one of the desired ongoing design advantages of the substrate coating at a given time can be met.

Some categories of tools, such as broaching dies and nozzles, are even more expensive because there is the additional cost of ensuring even circulation of CVD vapors through the die opening to deposit the coating where it is most needed. CVD gas diffusion is slow and the penetration is usually 500 to 10,000 nm or less. First, at these thicknesses, the coating is worn through to the underlying carbide before most of the wire diameter or pipe tolerance is consumed. Secondly, normal die reuse with larger diameters must be carried out without a hard coating. In many cases, the extension of the total lifetime may not be proportional to the additional cost of the CVD.

Currently, external coatings are the most commonly used industrial solution for increasing the quality of flat sintered tungsten carbide products.

Increasing the thickness of outer layer deposits to give a longer life, however, has harmful side effects, namely a tendency to increase

187 539 susceptibility to cracking and for rounding sharp edges of the tool, negatively affecting the optimal cutting or die geometry.

Combined mixtures and coatings

The CVD coating and the mixed hard alloy particles, the combination of (1) and (2) above give a very limited additional beneficial effect, while showing the same disadvantages.

cermets

Cermets are ceramic particles dispersed in a metal oxide or carbide matrix. Cermets combine the high temperature resistance of ceramics with the firmness and toughness of carbides. They cost almost the same as flat tungsten carbides and their consumption is also almost the same except for small finishing cuts, where flat carbide is recommended.

Sintered abrasive composites

The fourth case, described in the book De. Randall M. German 's, Liquid Phase Sintering, Plenum Press, New York 1985 (and practiced many years earlier in Russia) has led to obtaining a class of extremely abrasive composites for grinding and sanding media as well as tools for making cavities.

These composites are made by mixing diamond particles (or cubic boron nitride, cBN) and cobalt powders or capturing them in a metal (nickel) electroplated sludge and by hot pressing at lower temperatures. An alternative solution is to coat the diamond (Iub cBN) with an intermediate layer of transition metal carbide (which moistens the diamond) and chemically binds it with other low melting point, non-wetting but ductile metal binder such as cobalt, iron or nickel. Transition metal is used only as a chemical bridge in thicknesses not intended for carrying structural mechanical load. The metals used as the main matrix of the binder have good sintering ability, however, relatively low melting points, elasticity and strength modules. Such materials have desirable properties in abrasive applications. In most of these applications, diamond accounts for 10 to 60% by volume of the composite. The binder coatings have a thickness of several micrometers to assist machining at low temperatures (to avoid graphite degradation of the diamond) and dilute the diamond content, however, at a significant cost of mechanical properties. The properties of these composites depend on chemical factors, not mechanical properties regarding the modulus of elasticity, strength or fracture toughness. Thus, with a large diamond particle size and high binder concentration, the mechanical properties of the composite are determined by the composition of the mixtures. The compositions are selected to provide separation of the diamond particles in the final microstructure, which ensures that slight diamond-diamond interaction occurs. A slight strengthening of mechanical properties was found in one micrometer in the grain size range at nano scale for cemented carbides.

Requirements for milling tools include relatively large grains (50,000 to 600,000 nm) for increased metal removal, bonding of these particles to the wheel, proper spacing between particles (low concentration of particles with extensive bonding of the binder phase) to enable removal of workpiece particles and for long retention grinding wheel geometry. Such materials form metals by removing workpiece particles as a result of the difference in hardness between abrasive particles and workpiece particles. These types of abrasive composites are sometimes used for cutting tools used in machining materials of particularly high hardness at a relatively high speed, however, with a very slow chip removal rate (load). (See Fig. 6). The cutting effect of diamond cutting tools is very different from that of cemented carbide tools. Restrictions on the use of diamonds or composites in cutting tools are due to their cutting behavior. These types of composites work as abrasives that rub the workpiece rather than removing chips under heavy loads. In this way, very hard diamond particles are held by stretch bonding. When slipping through the workpiece, the diamond is exposed

187 539 for the incision of the opposite surface, however it is resistant to wear and the warp is eroded and gradually reveals the diamond. Cutting is carried out by the protruding diamond particle as long as it remains sharp. When the diamond blunts, becomes rounded, warp is subject to wear. In this way, the diamond is drawn through the workpiece and the matrix erodes until the next diamond is exposed.

Such hard, brittle abrasive composites are also used in some tool applications such as masonry drills and saws. They are also used for expensive wire drawing dies, and in some cutting tools where their operation is enabled by the presence of steel or other strong filling.

Functionally gradient materials (FGM)

The problem with coated products is their incompatibility between the mechanical, chemical or thermal properties of the layers. To correct this problem by achieving a gradual transition between incompatible layers, FGM materials have one or more of the following variables: chemical composition, microstructure, density, or various forms of the same material. The next purpose of the coating is to modify the electrical, thermal, chemical or optical properties of the substrate on which the FGM material is applied. The main disadvantage of this type of material is their tendency to degrade in places where the properties change and the difficulty of producing such materials.

The object of the invention is to obtain sinterable particulate materials called Ductile Coated Hard Powders (TCHPs), which have better parameters compared to the hard products and tool materials known to date. Such particles and products made from them combine the best mechanical properties regarding strength, hardness, high modulus of elasticity, resistance to cracking, low degree of interaction with the workpiece and low coefficient of friction, which occur separately in conventional materials, in a product with mismatched properties.

Another object of the invention is to reduce the cost of obtaining such materials. For example, tool inserts must be supplied in a wide range of various geometric shapes to fit various tool holders. In addition, the tool materials available today must be designed for very specific applications. Therefore, for each of these geometric variations, various material selections should also be offered (uncoated, CVD coated, PVD coated, cermet, ceramic material, polycrystalline cBN, polycrystalline diamond). The combination of geometric and material changes requires costly cataloging, providing a wide range of tools, costly delivery and inventory with unique packaging and identification, and also requires sales efforts to clarify and sell the entire complex set. Another object of the invention is to reduce the waste and costs associated with the production of currently known tools by developing tools for a more general purpose and higher performance at a moderate cost.

Furthermore, the method for producing the product according to the invention aims to reduce the manufacturing costs of the products made according to the invention.

The next goal is to achieve a significant cost reduction by extending the life of the product and by reducing the cost of manufacturing the products. The fact that the products according to the invention are uniform on the macroscopic scale, and not coated, gives users or suppliers the possibility of cost-effective grinding and re-use of initially used products. Another object of the invention is to obtain the same good quality mechanical properties of the materials according to the invention as with other hard products.

Another object of the invention is to develop a material having increased wear resistance and compactness for use in a wide range of products including tools (such as broaching dies, extrusion dies, forging dies, cutting and stamping dies, molds, forming rollers, injection molds, shears, drills, cutters and turning knives, saws, worm cutters, broaches, reamers, dies and dies), individual mechanical parts (such as gears, cams, plugs, nozzles, seals, valve seats,

187 539 pump impellers, revolver heads, pulleys, bearings and wear surfaces) integrated co-sintered components for replacement of fitted parts (connecting rods of an internal combustion engine, bearings) and / or for obtaining hard surface zones in mechanical parts made of powdered metal (P / M) forged or machined steel parts with heat-treated zones (such as cam shafts, gear parts, printer / copier parts), heavy industrial products (such as deep well drills, teeth of mining and earthworks equipment, hot rollers of steel mills) and electromechanical components (such as reading heads, specialized magnets). In addition to obtaining such new products, the main purpose of the invention is to obtain new composite molecular materials (i.e., TCHP's), new methods for producing such materials, and new methods for producing products from such materials.

To accomplish these and other purposes, a sintered material has been developed comprising a plurality of core particles that consist essentially of a first metal compound having the formula MandXB. M is a metal selected from the group consisting of titanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum, tungsten, aluminum and silicon. X is one or more elements selected from the group consisting of nitrogen, carbon, boron and oxygen and a and b are numbers greater than zero to four inclusive. The intermediate layer surrounds each of the core particles and consists essentially of a second metal compound with a composition different from the first metal compound. The second metal compound has a higher relative fracture toughness and is suitable for binding to the first metal compound and is also suitable for binding to iron, cobalt or nickel. The core particle with the intermediate layer forms numerous coated particles. The outer layer covers the intermediate layer on the coated particles and functions as a binder. It contains iron, cobalt, nickel, their mixtures, their alloys and their intermetallic compounds.

Preferably, the coated particles have an average particle size less than about 2000 nm, and most preferably less than about 1000 nm. It is also recommended that the intermediate layer has a sintered thickness in the range from 5% to 25% of the diameter of the core particles. It is also recommended that the outer layer have a sintered thickness in the range from 3% to 12% of the diameter of the coated particles. It is believed that with this outer layer thickness, the deformation areas associated with the displacements in one coated particle are passed through the outer adhesive layer to the immediately adjacent intermediate layer. Preferably, the first metal compound consists essentially of a stoichiometric compound such as TiN, TiCN, TiB2, TiC, ZrC, ZrN, vC, VN, cBN, Al2O3, SisN4 or A1N. It is also recommended that the second metal compound consist essentially of WC or W2C, but most preferably WC. Such materials have a higher fracture toughness than cubic boron nitride.

The preferred solution of the sintered material comprises a plurality of core particles consisting essentially of cubic boron nitride with an intermediate layer on each of the core particles, this layer essentially consisting of WC. The intermediate layer has a sintered thickness in the range from 5% to 25% of the diameter of the core particles. The outer layer containing cobalt or nickel covers the intermediate layer and this outer layer has a sintered thickness in the range from 3% to 12% of the diameter of the coated particles. A combination of core particles, an intermediate layer and an outer layer forming an outer particle, preferably having an average size less than about 1000 nm.

The next preferred solution is sintered material containing a plurality of core particles, wherein the core particles consist essentially of diamond and / or cubic barium nitride from an intermediate layer on each of the core particles, which layer consists essentially of a metal compound having greater relative fracture resistance than core particles and a binder containing iron, cobalt, nickel, mixtures thereof, their alloys or their intermetallic compounds, wherein the intermediate layer has a sintered thickness in the range from 5% to 25% of the diameter of the core particles.

A further embodiment of the invention is a powder consisting essentially of numerous coated particles. The main part of the coated particles has composite core particles

187 539 essentially of the first metal compound having the MaXb-M formula is a metal selected from the group consisting of titanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum, tungsten, aluminum and silicon. X is one or more elements selected from the group consisting of nitrogen, carbon, boron and oxygen, and a and b are numbers greater than zero to four inclusive. Core particles coated with a surrounding layer consisting essentially of a second metal compound, with a composition different from the first metal compound, and have greater relative fracture toughness. This layer also has the ability to bind to the first metal compound as well as the ability to bind to a metal selected from the group consisting of iron, cobalt and nickel. Preferably, the coated particles have an average size less than about 2000 nm, and most preferably less than about 1 pm. It is also recommended that the layer surrounding the core particles after sintering has a thickness in the range from 3% to 200% of the diameter of the core particles. Recommended compositions of core particles and the surrounding layer (intermediate layer) are the same for the powder as for the sintered article.

It is also recommended that the outer binder layer consist essentially of cobalt, nickel, iron, mixtures thereof, their alloys or their intermetallic compound deposited on the outer surface of the second metal compound layer in the form of a continuous layer.

The subject of the invention is shown in the embodiment of the drawing, in which Fig. 1 is a schematic representation of a sintered material formed according to the first embodiment of the invention, Fig. 2 - a photomicrograph from a scanning electron microscope showing a cross-section of the sintered material produced according to the first embodiment of the invention at a magnification of 20,000 times Figure 3 is a schematic diagram of a powder production device according to the first aspect of the invention. 4 - diagram of the interior of the device of Fig. 3, showing the movement of particles within such a device during the deposition of the intermediate layer by chemical vapor deposition, Fig. 5 - rear view of one component in the recommended solution of the device of Figs. 3 and 4, Fig. 6 - graph graphical field of application of the sintered material according to the invention, used as a cutting tool in relation to conventional materials, and Fig. 7 - list of properties of sintered materials described in the examples.

The subject of the invention is a new type of material made from powders. According to the invention, the powder is in the form of multiple core particles. Core particles are designed to give their physical properties to the entire powder structure. As stated, the core particles consist essentially of a first metal compound having the MaXb formula, where M is a metal selected from the group consisting of titanium, zirconium, hafh, vanadium, niobium, tantalum, chromium, molybdenum, tungsten, aluminum and silicon, and X is one or more elements selected from the group consisting of nitrogen, carbon, boron and oxygen, while (a) and (b) represent numbers greater than zero to four. These metal compounds are hard, wear-resistant and chemically resistant to most environmental contaminants and workpieces. It is important for the invention that the core material can be exposed, such as when the powder is sintered to form a cutting tool and the sintered article is formed by milling, lapping and polishing to form the final shape of the article. This removes the intermediate layer of material above the core particles and exposes the core of the particles relative to the workpiece. As will be explained below, this is a significant advantage.

As stated, the core particles of the powders consist essentially of at least one stoichiometric compound. In some embodiments, the core compositions are different to impart properties to the various core particles formed therefrom. It is recommended that the core metal compound consist essentially of a metal compound selected from the group consisting of TiN, TiCN, TiE2, TiC, ZrC, ZrN, VC, VN, cBN, Al2O3, Si3N and A1N. Such materials can be used in the form of commercially available powders, whiskers, crystals, fibers and the like because the shape of the core particle may have technical significance. The core particle is covered by a layer of the next metal compound, referred to as the intermediate layer. Thus, the core particle material must have a certain degree of compatibility with the material forming the intermediate layer applied to it and should have a composition different from the composition of the intermediate layer.

187 539

The powder of the invention comprises an intermediate layer applied to the intermediate layer applied to the outer surface of the core particle. The intermediate layer consists essentially of a second metal compound, i.e. a compound that is different in composition from the first metal compound that forms the core of the particle. The second compound, the intermediate layer, has a greater relative fracture toughness than the core material. In addition, the second metal compound must be capable of binding to the first metal compound and be capable of binding with iron, cobalt, nickel, mixtures thereof, their alloys or their intermetallic compounds. Preferably the second metal compound consists essentially of WC or W2C. As will be disclosed below, the combination of a relatively ductile and strong intermediate layer and a hard core forms a powder and a sintered material formed therefrom with exceptional mechanical properties. This also applies to the dimensions and thickness of the layer of coated particles. In particular, the particle sizes and layer thicknesses provide properties that could not be predicted by the classical calculation rules of the mixture. This will be described in more detail in the section on sintered products. In any case, it is recommended that the coated particles have an average size less than about 2000 nm, and most preferably less than about 1000 nm. It is also recommended that the intermediate layer has a thickness in the range from 5% to 25% of the diameter of the core particles.

The thickness of the intermediate layer has a significant impact on the mechanical properties of manufactured products. It is believed that when the coated particles (core with an intermediate layer applied to it) have a mean diameter graphically measured in a photomicrograph in a cross-section using an average free path of less than 2 pm, resistance to dislocation movements within adjacent sintered particles is increased , improving the mechanical properties of the sintered product. Even with the use of the classic mechanical phenomenon, using the analysis of marked elements, it turns out that increasing the thickness of the spherical toilet cover surrounding the TiN ball from about 1 pm to about 0.4 pm increases the theoretical brevity by over 40%.

It is further recommended that the intermediate layer has a pre-sintering thickness in the range from 3% to 200% of the diameter of the core particles. During sintering, the thickness of the intermediate layer may be reduced as a result of interaction with the core material, particle / particle interaction, boundary phenomena and grain growth. Thus, to obtain the desired thickness of the intermediate layer in the final sintered product it may be necessary to use an initial thickness of up to 300% of the diameter of the core particle.

The recommended powder form should have an outer layer of binder applied to it. Conventionally, metal binders are applied to metal compound particles by milling them with metal powder. This physical action lasts a long time and when only a small percentage of ground powders (6%) is the metal of the binder, the time to lubricate the binder metal on the surface of the remaining 94% of the particles negatively affects the efficiency of forming sintered products using metal binders and can cause damage to the coated particles . The present invention contemplates the use of such particles as a uniform coating on the outside of the metal compound particles in the form of a continuous layer. According to the invention, the binder layer consists essentially of a metal selected from the group consisting of iron, cobalt, nickel, mixtures thereof, their alloys and their intermetallic compounds. Preferably the continuous binder layer is deposited by chemical vapor deposition, cathodic sputtering, electroless plating, electroplating, physical vapor deposition, carbonyl deposition, by solution spraying or plasma-assisted physical vapor deposition. Because cobalt and nickel are compatible with the recommended types of core particle material and the recommended intermediate layer materials and have better high temperature properties, they are the preferred binder metal compositions.

A further embodiment of the invention is sintered material. This sintered material contains numerous core particles consisting essentially of a first metal compound having the MaXb-M formula is a metal selected from the group consisting of titanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum, tungsten, aluminum and silicon. X is one or more elements selected from the group consisting of nitrogen, carbon, boron and oxygen, and a and b are numbers greater than zero to four inclusive.

187 539

Preferably, the first metal compound is predominantly stoichiometric and consists essentially of a metal compound selected from the group consisting of TiN, TiCN, TiB2, TiC, ZrC, ZrN, VC, VN, cubic BN, Al2O3, S13N4 and A1N. Such metal compounds are hard and have some other useful mechanical properties, however, they have limited resistance to cracking (ability to inhibit a propagating crack). Other metal compounds may also be used in the invention, however the compounds previously described are preferred.

The choice of composition for various parts of the particles may be based on conventional information regarding the known properties of the materials considered at the macroscopic level. For example, it is known that diffusion resistance can be estimated for a variety of materials by considering their standard free energy of forming at operating temperature. Taking WC, TiC, TiN and Al2O3 in order, they have increasing negative forming energies, and therefore TiN is considered to have significantly reduced diffusion consumption compared to standard WC cermets.

In addition, the dissolution rates of various tool materials in iron (a typical workpiece) at temperatures in the range of 1000-1100 ° C, differ significantly. The comparison shows that the significant presence of TiN on the surface of the tool will provide a significant reduction in the dissolution of WC in iron, for example at 500 ° C, the relative dissolution rates are as follows:

WC: 5.4 x 1O4

TiC: 1.0

TiN: 1.8 x 10'3

AI2O3: 8.9 x IO '

It is believed that these principles explain the improvement of the wear behavior of WC tools compared to iron, when the WC is accompanied by a TiN core, i.e. the exposed TiN core will provide less diffusion wear in iron than WC. A continuous toilet particle coating is necessary to achieve strong coverage and good mechanical properties (Young's modulus of 696 GPa, compared to 250 GPa for TiN). TiN core (having hardness in Vickers units Hv = 2400 compared to Hv = - ^ 2350 for Wc, and having a friction slip coefficient (.1 = 0.125 compared to pu-0.200 for WC) will reduce wear frictional to iron, whereby the core will be exposed on the surface of the tool after its final grinding and polishing.

It is also possible for the core particles to be a wide variety of metal compounds, as long as each of them is compatible and different from the material constituting the layer covering the core particles. In this way, the properties of a product made of sintered material, when the core particles are exposed by removing the cover portion of the intermediate layer, are determined mainly by the properties of the core particles, their concentration in the sintered material and their combinations. For example, if it is desired to form a sintered article in the form of a cutting insert, then the sintered article should be ground or shaped by EDM (electrical discharge treatment) to expose the core particles. In the recommended solution where the core particles are TiN and the intermediate layer is WC, the TiN friction coefficient, its hardness and wear resistance give these properties to the cutting insert, while the overall strength of the insert and its resistance to crack propagation is increased by the toilet layer surrounding the TiN core particles . It is important that wear of the insert will not cause deterioration of the properties of the insert because TiN is not a coating that is subject to wear. It is an integral part of the insert material, which reveals a new surface as it gets worn. The recommended core material is cubic boron nitride (cBN), however, this solution requires the use of specific particle size and thickness and layers to realize the potential of the cBN core particle. It is believed that the extremely high hardness cBN must be integrated into the product by applying a load-bearing layer surrounding another metal compound of such a composition and thickness that the resulting particle coated with this layer after sintering will have useful technical properties as the structure above for its grinding application.

187 539

This sintered material solution includes an intermediate layer on each of the cBN core particles, which consists essentially of WC or W2C.

This solution further includes an outer layer covering the intermediate layer on the coated particles. The function of the outer layer is to create a binder and combine the coated particles at appropriate sintering times and temperatures to form a dense sintered material. The outer layer used here acts as a binder. It is made of iron, cobalt, nickel, mixtures thereof, their alloys or their intermetallic compounds. As stated above with respect to powder, the invention contemplates the use of such binders as a uniform coating on the outside of the metal compound particles in the form of a continuous layer.

The size of the core particles coated with an intermediate layer (collectively referred to as "coated particles") has a significant impact on the mechanical properties of the sintered material and products made from it. As stated above, relative to the powder, it is recommended that the coated particles have an average particle size less than about 2000 nm and preferably less than about 1000 nm. It is also recommended that the intermediate layer has a sintered thickness in the range from 5% to 25% of the diameter of the core particles. In addition, it is believed that the thickness of the binder layer also affects the properties of the sintered material.

It is recommended that the outer binder layer have a thickness after sintering in the range from 3% to 12% of the diameter of the coated particles. Sintered material having such dimensions is believed to have improved properties because the stress areas associated with dislocations in one coated particle are passed through the intermediate layer to the immediately adjacent core particle. The invention works with an intermediate layer having a thickness after sintering in the range of 3% to 200% in diameter of the core particles, however, a thickness in the range of 5% to 25% is recommended.

It is known that increasing firmness is a normal result of decreasing grain size. Recommended core particle diameter is in the range 100 to 1000 nm. This particle size range interacts with the thickness of the intermediate layer.

The strength of the crystalline substance depends on the atomic bond and dislocation structure. Dislocations are linear atomic mesh defects that are usually fixed and stationary. In a mixture of two atomically bonded crystalline materials, the upper and lower bonds set the composite modulus of elasticity, calculated by the mixture rule and the inverse mixture rule. After being subjected to increasing load, the material deforms elastically until the dislocations in the grains start to flow or move, which leads to the onset of permanent deflection and a reduction in useful strength. At particle sizes of about 1 micrometer and below, extremely high strengths arise in these materials, mainly due to dislocation stresses.

Around each dislocation there is a cylindrical strained area that extends outward into the surrounding mesh. Theoretically, this stress area around each dislocation must be balanced by the opposite stress area, otherwise the dislocation will move beyond these surfaces. When the crystal size is large compared to its stress area, no mirror stress is created around the dislocation as long as it is at the crystal surface. In sintered material having a binder connecting numerous crystalline particles, the mirror tension is adapted to the lower strength of the binder matrix, however, for large crystals there is obvious correction, since most dislocations are not near the surface.

In submicrometer polycrystalline particles, the stress region may extend to adjacent grains whose atomic grid is probably not aligned with the grain of the stress region. This balancing of the stress area outside the grain surface limits the dislocation movement, thereby limiting deflection. When the grain size decreases further, more dislocations are close to the surface and the strength may decrease.

It is believed that when the thickness of the intermediate layer and the binder layer connecting the particles coated in the sintered material are thin enough, the stress area actually passes through the binder matrix and into adjacent particles. It causes formation

187 539 high strength, irrelevant to the bonding material (in this case the binder) between the hard coated particles. In other words, the mechanical properties of the sintered product are independent of the properties of the binder phase, assuming, of course, that it is a crystalline and very thin binder.

The thickness of the intermediate layer should be sufficiently large relative to the core to form a mechanical cellular support matrix passing through and around the core particles. In addition to this goal and the expected increase in mirror stress strength with core powders of 1000 nm in diameter and smaller, surprising strength properties can be obtained in sintered TCHP alloys, obviously as a result of particle size, properties of the core material and properties as well as the thickness of the intermediate layer and binder.

For reasons not yet fully explained, the tungsten carbide (WC) coating with a content of 5 to 10% of core particles of 100 nm or smaller is actually very thin and can function as if it contained much smaller particles of the solid phase (50 to 10 nm), effectively achieving mechanical properties at the nano scale with much larger and easier to handle particle sizes.

TCHP structure with a small size of hard core particles and ductile sheaths on the nanometer scale, separated by thin cobalt ligaments less than 1 micrometer between grains, maximizes flexibility, hardness, crack resistance and strength. The most interesting is the possible loss of the "composite" character of the mechanical properties of sintered TCHP as a result of thin bonds of the binder. Even for a material with low hardness (such as cobalt), mirror stresses resulting from dislocations near the surface (all of them are close surfaces in submicrometer grains), the composite properties are higher than those obtained in abrasive composites. It may also be that when the bond matrix bindings become very thin and the composite strength becomes independent of the plastic properties of the cobalt binder, the structural strength of cellular coatings may dominate and in principle be closer to the strength of WC.

According to the invention, sintered metal particulate materials have been developed that allow optimal balance of properties (ductility, strength, low friction coefficient and hardness). The expected working advantages of dies and other tools made of TCHP are ternary: (a) a lower coefficient of friction at the interface between the workpiece and the tool, resulting in reduced heat, wear and cratering, and requires less machining power and the auxiliary use of externally supplied lubricants, which at the same time results in longer tool life and better process control, (b ) low reactivity towards iron, reducing sticking and diffusion, side or matrix wear, but in turn extending the life of the die matrix and (c) sintered tool microstructure in which the tough, durable coating material (WC) on the particles creates a cellular supporting macrostructure for the tool, while providing a well-embedded and firmly bound protective layer for hard particle cores ( TiN), holding them in position and enabling optimal exposure and maintenance of the hard phase with a wear resistant tool surface.

This is in contrast to products manufactured by conventional methods (where the relatively low strength of the binder between particles and the binder reduces the level of firmness and bending strength), or in which the sintered product is completely coated to give it hardness, whereby the thin coating has a limited life or breaks .

Placing the hard phase alloys inside as a core particle (instead of outside) distributes the hard phase alloys (exposed at the outer surface after final grinding) through the sintered microstructure of a much larger proportion (or thickness) than is possible with any known conventional material. This increases wear resistance, reduces chemical interaction with the workpiece, and significantly reduces the coefficient of friction. The service life of the tool is extended by constantly renewing the surface of the grains that wear out or are removed by

187 539 opposite sliding surface. Likewise, the wear resistance and adhesion properties of most recommended core materials are known for their quality in conventional materials, so that their quality in application to core particles is foreseeable in the light of the present disclosure. Because the core particles are coated with known materials (e.g. WC), mixing and sintering together coated particles having several different core materials will facilitate the improvement of multiple properties. Thus, the cost of development and testing is reduced, while the final material is obtained with unique properties. Thus, by designing a sintered microstructure in which each particle has a tough sheath (intermediate layer) that adheres very strongly to its neighboring particles to form a ductile cellular support system through the sintered product substrate, a sintered product is obtained with the highest possible combination of strength, high modulus of elasticity, resistance for cracking and hard alloy content.

The resulting macrostructure of the product is a cellular microstructural frame built of ductile, durable, strongly interconnected coated particle shells, each of which contains and supports one or more mechanically and chemically bonded core particles, crystals, fibers or nickel crystals, exposed in cross section at external surfaces during final grinding and polishing. This principle of optimizing the combination of various materials for core particles and the surrounding intermediate layer enables the combination of usually contradictory product qualities (e.g. strength and hardness) at levels not previously encountered in the field of powder metallurgy.

This idea gives the material designer a variety of tools (used alone or in combination) and a valuable way to ensure easy and complete control over the adaptation of the TCHP particle structure (intermediate layer thickness, size and core materials) and mixtures (combining various powders into a tool and product zone) to meet many different unique, combined and especially needed conditions in a single product and tool.

In addition, by using a standard strong material (such as toilet) as the tough outer shell of the particle, a significant reduction in research, development and industrial efforts is obtained, because only one precursor gas of the material reaction (tungsten carbide) will have to be used to coat the powder particles, instead of many tens complex precursor and reaction gases used for various external substrate coatings. Such particle materials will be sintered as if they were made of tungsten carbide particles, which are known to bind very strongly to adjacent tungsten carbide particles with a binder such as cobalt. So the standard binding material used for over 60 years will penetrate and strengthen the entire structure. An increase in tungsten carbide thickness on a particle to meet strength requirements or a reduction in thickness in more critical wear applications will result in the development of most design solutions. Increasing the core particle size can meet or reduce most of the major requirements for wear resistance for applications that require greater strength. By using a variety of core particle materials with properties (hardness, friction coefficient) known or found to perform better in specific applications (such as lateral wear or crater wear), it is also implemented by selecting core material. It is also possible to mix the above thicknesses, diameters and powder parameters of the core material to solve most critical applications.

It is also possible for TCHP to gradually change from zones or layers rich in harder phases to phases from more ductile intermediate layer materials using pre-heated wax / powder extruded sections. It is a more flexible and effective process than currently used in functionally gradient materials (FGM).

The present invention can also be used to merge different layers of powder (or mixtures) in different areas of the same part for better prevention

187 539 various quality assumptions. This enables direct purification of the microstructure design without atomic level gradient. Co-sintered with other metal powders to give local hardening in "not" sintered parts, TCHP will allow the replacement of steel parts requiring heat treatment by powdered metal (P / M) parts requiring fewer manufacturing operations.

Fig. 1 shows the sintered material in a schematic section. In this embodiment, one or more hard metal compound particles 10 with an intermediate layer 14 of a ductile hard metal compound such as tungsten carbide are present. The coated particle comprises an outer layer of a suitable sintering binder 16, preferably of iron group metals, usually cobalt or nickel. The resulting coated powder 18 is finally sintered to a semi-finished or finished product whose micro section is generally designated 20.

The microstructure of the sintered product 20 is a cellular frame with a strongly interconnected unitary toilet layer 14 containing and supporting its own tightly bonded metal compound core 10, held within the matrix 16 and exposed in cross section at the outer surfaces 22 during final grinding and polishing.

The photo from the scanning electron microscope shown in Fig. 2 shows a unitary TCHP particle containing a core particle 6, 1.6 micrometer of titanium nitride coated with a 7 layer about 0.25 micrometer (15%) thick2C. It is one of many TCHP grains placed in a resin metallurgical sample, shown in background 9 and polished. It is known that hard alloy particles often do not sinter sufficiently close to theoretical density as a result of (a) irregularities in such grains (resulting in poor flowability, requiring hot pressing), and (b) low plastic deformation during consolidation.

The digit shape of core particle 6 shows concave irregularities typical of the samples. The CVD coating process usually fills the concavities shown at 8, resulting in coated particles having a more rounded and smoother shape than as a result of flowability and thickening of powders. This reduces processing costs, giving a more uniform and thinner binder layer, and helps to thicken powders, which in turn improves the mechanical properties of the sintered product.

The unique powders of the invention were made in a chemical vapor deposition reactor (CVD). Due to the size of the coated particles, the reactor contained components to prevent the coated particles from caking. A diagram of the reactor is shown in Figures 3-5.

The CVD reactor of Fig. 3 consists of a rotary tank 20 of the CVD reactor contained inside a furnace 22 for heating powders and reaction gases, which gases are fed into the reactor and drawn out through the gas inlet and outlet pipes (36, 26) at opposite ends, respectively . Line 30 provides the tungsten hexafluoride precursor WFó, and line 28 supplies 99.999% pure hydrogen, two gases that react in the reactor vessel 20 to form a CVD coating attached to the rotary seal and inlet line 36 through flow meters 32. Line 28 also passes through a gas bubbler 34 containing 99.9% isopropyl benzene. A filter 38 is located at the outside of the reactor 20, in front of the discharge line 26, which line is operatively connected to a vacuum system (not shown), trap 40 and flow meter 42. The reactor 20 may be in the form of a refractory metal or graphite cylinder, capable of rotating at a variable speed in the range of 50 to 150 rpm depending on the drum diameter and specific weight of the coated powder, as well as with a change in its orientation, i.e. angle of inclination 24 and speed the revolutions can be set to obtain the correct residence time of the coated powder within the generated high temperature reactive gaseous environment (500-1600 ° C).

There are four significant problems in the practice of the CVD method for the production of the TCHP submicron molecular component: (1) the current cost of tungsten hexafluoride precursor gas (WFć), (2) controlling the harmful properties of WFó, (3) premature reaction of precursors on surfaces other than on core powder and (4) breaking

187 539 agglomerates. The last three problems have technical solutions. Although other benefits of machining costs can eliminate the first problem, the direct success of CVD is determined by its cost over other methods such as metal carbonyl deposition.

It has been found that the solution to the third problem (inefficient use of reagents) is to keep the gas below the threshold reaction temperature until it is close to the core particles. This can be further improved by keeping the reaction gases separated and then mixing them with each other and with turbulent heated powders.

It has been found that microwave energy (but not induction frequencies) will cause heating of the particles. At 2.45 Ghz, heating for about 2 minutes at 500 watts resulted in a temperature rise of about 37-40 ° C. High heating rates in the focused, turbulent flow of reagents heated by the powder alone (heated by microwave energy) in the recirculating quartz tube allowed for homogeneous spraying, mixing, recirculation and coating of submicron powders.

Figure 4 shows a solution to the problem of caking powder. The fluidization process in a rotary reactor usually does not use the forces needed to break up the lumps that build up continuously. In fact, if nuggets are left uncontrolled, they show an intrinsic tendency to classify by size, which further impairs uniform processing. In addition, the conventional horizontal reactor has end zones that reduce the uniformity of coating thickness in the batch as shown in Figure 4, the solution to the problem of caking and end zones that caused non-uniform coating included tilting the reactor and installing a fixed comb-like guide 80 for (a) causing recirculation and homogenizing the batch and (b) applying sufficient shear to the powder to cause spraying.

Inside the furnace, reaction chamber 62 is made of graphite lined with a 60 quartz cylinder. Rotational speed 66 must be such that the gravity acting on the core powder is greater than the centrifugal force, so that falling powder grains, thereby fluidized to maximize exposure to reaction gases, accumulate the intermediate coating. The purpose of this is to cause the flow, rolling, cascading and tumbling of the core powder by a simple combination of centrifugal force, gravity and rotational inertia originating from cylinder rotation to maximize powder exposure to precursor gases. This imposes a practical diameter of 64 as greater than 120 mm. To assist the breaking of agglomerate nuggets that interfere with the deposition of homogeneous layers on each particle, the reaction gases should be introduced at a high flow rate through the falling powder to break the agglomerates due to shear force.

Shear is double applied to powders in two zones of the guide 80, shown in section 67 at the lower end of the drum. The first zone 68 causes a small pressure and shear force to be applied to a portion of the powder when it is suspended below the guide through a rotary drum 60, 62. A progressive compression angle 69 of 13 degrees is formed between the drum and the suspension 67, which angle results in the application of sufficient compressive force shear to break up agglomerates. The second zone 70 consists of longitudinal angular teeth 72 forming a self-suspension, cut squarely, with slight mixing at the edges in stainless steel. This zone 70 allows the squeezed powder to escape under the effect of a low shear force which serves to further break up and homogenize the particles for exposure during the next rotation. At a distance 74 of 5 mm from the quartz liner 60, the progressive angle of the suspension teeth ends with an inflection point, which causes an increase in compression when the holes of the teeth 72 reach their maximum value. A small clearance 76 of 0.5-1.0 mm protects the quartz from scratching by the suspension.

The helical suspension zone 80 is a guide 78 shown at the lower end of the reactor (and shown at its upper end with dashed lines). This spiral guide raises the powder to ensure lateral recirculation and homogeneity of the batch.

187 539

Fig. 5 shows a spiral suspension illustrating the spiral guide 80 more clearly. In the upper platform, holes 92 are cut out to allow the accumulated powder to recirculate. The suspension teeth 90 are also clearer.

As discussed, the preferred embodiment of the invention uses pre-ground molecular core powders made from titanium nitride. This powder is coated with a CVD intermediate layer of tungsten carbide. The use of sintered cobalt binder is recommended. In the TiN / WC / Co system, there is good solubility of W in CO and an efficient reaction between C and TiN to form Ti (C, N), leading to a strong TiN / WC grain boundary phase and excellent mechanical properties of the sintered product, although the bonding is less strong than the bond that can be made between W and Co.

The TiN phase is located inside the material and there is no reduction in quality as a result of surface wear (as is the case with traditional tools protected by ceramic coating). For this reason, dies, tools or other hard products made of this type of TCHP can be reused for larger diameters or regrinded for other applications. If it is assumed that the formation of Ti (C, N) interlayer must be minimized in order to increase the binder efficiency, then it is possible to increase the thickness of the toilet coating and reduce the sintering time and temperature by depositing the vapor of the binder layers on the particles. On the other hand, with a Vickers hardness of Hv = 3200, Ti (C, N) is much harder than TiN at Hv = 2400 or TiC at Hv = 2800. This may be beneficial for some applications. Zirconium nitride, Zrn harder than TiN, has a friction factor of 2/3 lower than for TiN, and is considered better with lateral wear. It is also the recommended core material.

Figure 6 shows the compilation of the working fields of numerous conventional tool materials and the expected working field of the inventive solution used as cutting tool material. By using conventional hard materials as the core, reducing the particle size to the desired range and using a ductile coating (such as WC) of the appropriate thickness on the core, the TCHP of the invention broadens the working fields of using such conventional materials. The range of increase in the tool feed rate, i.e. the border of the right side of the area defining the working area of the TCHP according to the invention is based on the increased firmness resulting from the ductile coating and the use of hardness and other properties of the core material.

Using the reactor system as shown in Fig. 3, the sintered composite particulate materials of the invention can be prepared using any of the following alloys in the form of a powder with a diameter of 1000-1500 nm: titanium nitride, titanium carbide, zirconium nitride, vanadium carbide, aluminum oxide, and cubic boron nitride (other alloys such as titanium diboride, zirconium carbide, tantalum nitride and niobium carbide may also be used). The reaction components for chemical vapors used for WCx deposition are tungsten hexafluoride (WF—) in the presence of hydrogen and an aliphatic or aromatic carbonate compound whose components react at temperatures in the range of 500 ° C to 700 ° C to form WCx coatings with highly reproducible properties. Low pressure (e.g. less than 10 kPa) should be used in the reactor to increase the diffusivity of the reaction substances in the gas and to allow the formation of a homogeneous coating on the powder surface. This technology is usually called LPCVD (low pressure chemical vapor deposition). The reactor is started at a speed sufficient to tumble the core powder in an uninterrupted free-falling run, and the speed of the reaction gas is regulated as a function of other parameters (pressure and total flow rate), the gas bubbling unit is used in those cases where the reaction component is used aromatic liquid compound.

The target coating thicknesses, based on the desired 90-95% strength of all sintered WCx carbide and based on minimizing CVD residence time, is in the range of 2 to 25% of the average particle diameter. CVD operating parameters are adjusted using a computer program, thus enabling their optimization following the main "indicator", eg the thickness of the WCx coating at various locations of the reactor. number of embedded WCx

187 539 on powder is estimated by EDX microanalysis of the processed powder by comparing the tungsten and titanium intensity peaks and the WM: TiK ratio (where M and K are atomic ratio coefficients), determined on particle samples taken at various furnace locations and at different times. This gives an indication of the uniformity, deposition rate and properties of the WCx surface and intermediate surface WCx / core particle, before sintering. The cross-sectional thickness of the WCx coating is observed by means of an optical microscope and a scanning electron microscope, using a sample containing TCHP grains embedded in the resin and polished to expose the cross-section of the grains, while X-ray analysis is also used to show the presence of the WCx phase on the powder.

Examples

Three series of sintered samples were made: a series made of WCx coated titanium nitride molecular material (according to the invention, formulas C, D, E and F), a series of reference bars made of tungsten carbide powder without any coating (formula A), a comparison series made of a mixture uncoated tungsten carbide powder and TiN additive (formula B) and standard SANDVIK material (see column G in Fig. 7), coated with TiN, TiC and Al2O3 (formula G).

Tungsten Carbide Toilet Powder (used to make formulas is commercially available from HC Starek Company as DS 100 grade having a typical average particle size of about 1000 nm (± 100 nm). The cobalt powder used was Starek grade 11, having a typical particle size of 1500 nm (± 200 nm), Starek grade C was used as the titanium nitride powder, having a typical particle size of 1000 nm (in the range between 800 to 1200 nm), and the nickel powder used is commercially available with a typical particle size of 2200 nm.

The formulas of the invention contained TiN core grains coated with CVD tungsten carbide (W2C) to a thickness of about 160 nm to form a composite TCHP particle material having a particle size of about 100 nm. The device described above with reference to Figures 3 to 5 was used to cause CVD coating of TiN powder. It is actuated at a spiral angle of 20 ° and with a comb attached at a 13 ° compression angle. The appropriate amount of TiN powder was introduced into the graphite reactor chamber. The system was cleaned, hydrogen flow initiated, and internal pressure set to 1.45 kPa. Power was then connected to an electric furnace to raise the temperature of the reactor drum rotating at 90 rpm to about 550 ° C (about 1 hour). The flow meters for the WF feed) were then opened, and the cumene bubbler to obtain a molar ratio of reagents suitable for W2C deposition on the TiN substrate powder; the bubbler was operated at 20 ° C, and hydrogen gas was used as the carrier gas for liquid cumene. This type of operation was continued for a period of time sufficient to produce the desired W2C thickness on the TiN particles, after which the WFć flow meter and cumene bubbler were closed and the furnace was cooled with hydrogen.

Formula A is a double mixture consisting of 94% by weight WC and 6% by weight Co, formula B is a triple mixture consisting of 87% by weight WC, 6% by weight Co and 7% by weight TiN, formula C consists of 84% by weight of the described TCHP composite and 16 wt.% Ni, Formula D consists of 84 wt.% TCHP composite and 16 wt.% Co, while Formula E consists of 90 wt.% TCHP composite and 10 wt.

Formula B was made to sintered cubes, 53 x 15 x 11 mm, weighing about 130 grams, by mixing the formula with Acrawax C (a working adjuvant in the form of ethylene bistearamide, available from Lonza Inc., Fair Lawn, New Jersey) and hexane. It was ground in a ball fluid for 16 hours using toilet balls, dried under vacuum, sieved through a 300,000 nm sieve, cold isostatically pressed at 200 MPa for 5 minutes and sintered at 20 minutes at 1450 ° C under conditions vacuum 0.1 to 0.4 kPa. The heating and cooling rates used were 150 to 200 ° C per hour, and all sintering required about 2 hours.

Sample discs were prepared from formulas A, C, D, E and F. For this purpose, the formula was mixed with a provisional macrophore binder and an alcohol solvent, milled

187 539 in a planetary mill using tungsten carbide grinding balls, dried at 80 ° C for 15 minutes and sieved at 300,000 nm. For samples A, C and D, the formed discs were 10 mm in diameter and sintered under the vacuum conditions described above for samples A and B. To produce samples E and F, the milled, dried and sieved formula was uniaxially pressed at 1400 ° C under 200 pressure kg / cm2 to create discs with a diameter of 50 mm.

Numerous samples of each of the sintered products were tested as described above to evaluate each of several properties. Fig. 7 shows the formula, sintering conditions (vacuum or hot pressing), product form (bar or disc), binder content after sintering, and values for several measured properties. The measurement of lateral wear and crater wear was made on a standard material (CK45) at a tangential surface speed of 200 m / min, with a cut depth of 2 mm and a feed speed of 0.2 mm / revolution. Hardness, flexural strength and elastic modulus values. Samples # 1 are known from the literature. In the above examples, the sintered samples of the present invention have been found to function in a way that makes component metal powder particularly well suited to the production of tools and other products.

It should be noted that the ability to change not only the metal compositions used in the production of the sinterable particulate materials of the invention (including any complementary binder or sintering aid), but also the relative thicknesses of the core particle and surrounding intermediate layer allows a high degree of control over the properties of the materials molecular and by articles made therefrom, for example, by changing the thickness of the sheath (e.g. up to a value that is usually, but not necessarily, 5, 10 or 15% of the TCHP particle), optimal balance of hardness, ductility, strength, wear and heat transfer capability, which are given to the sintered product can be obtained.

According to the invention, a new class of powder materials was obtained, i.e. tough, hard-coated TCHP powders that allow the production of sintered products that currently exceed the compromise level of conventional materials by combining the intrinsic lateral mechanical strength of metal carbides (or comparable ductile metallic compounds) with better wear resistance. hard metallic compounds at the core particle level. Tools or products made of such materials work well in a much wider range of conditions than the current specialized methods allow, and their quality / price or value ratio increases significantly.

The invention has been disclosed in the form of examples and recommended solutions. The scope of the invention is not limited to these, however, but is defined by the appended claims and their equivalents.

187 539

FIG. 2

187 539

Q

W (JS a?

II? <S £

ΙΛ H <<TS. ~

LOW TOOL FEED RATE LOW TOOL STRENGTH

HIGH TOOL FEED SPEED HIGH TOOL STRENGTH

FIG. 6

187 539

<td> 0</td><td>W / ITC coated SANDVK tool, TIN, A / 203 MALL GC415 (P15) type SNUN 120408</td><td> -14,9(=100%)</td><td> -1750</td><td> ?</td><td> -1790</td><td> -640</td><td> 0,16</td><td> 0,01</td><td>94 wt. Toilets</td><td>so</td><td>5pm (on the tool)</td>

<td>b</td><td>I ||| pi</td><td> £</td><td>and</td><td>Φ · 8</td><td>AND</td><td>73 cj</td><td></td><td>'φ 00 s</td><td>£ ffunction</td><td>Ό rM</td><td>1 sO</td>

<td></td><td>| 4 | hs</td><td>m n Ό</td><td>about ?</td><td></td><td>5 m Ό * 9</td><td>00 Axis C4</td><td></td><td>cT</td><td>g Ϊ ~ g</td><td></td><td>T</td>

<td>IN</td><td rowspan="2">Ig 1 and 8 8 p S | (p ~ a tfs s> 3 § hgfirf</td><td> 06 (=100%)</td><td> 1</td><td>Ά cn about about"</td><td>\ S F”< Λ loam</td><td>and (standard deviation = 2,192)</td><td>V> cn about</td><td>about"</td><td>wt% W2C TIN + W2C scales</td><td>ABOUT</td><td>and SO f</td>

<td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td>about</td><td></td><td></td>

<td>AT</td><td>Ł | a §2M ft C Ν χ • S 8.5 8 *</td><td>1 OO</td><td>S</td><td>r- cn about about*</td><td></td><td>and B</td><td>and L • s</td><td> 1 •8</td><td>eb £ l ! " and 1</td><td>ABOUT</td>

<td rowspan="2">m</td><td>equivalent TM6CO vacuum (50 ° C</td><td>• £ h * iio</td><td> 1(1</td><td rowspan="2">0.12 (measured on a sample made at M3D)</td><td> 2</td><td rowspan="2">no measurement</td><td> 1</td><td>and</td><td></td><td></td><td> 3 1</td>

<td>WCI connection block sintered at 1 '</td><td>«Η os gg</td><td>& § and Ό B OO Ps cn £</td><td> 1</td><td>L</td><td>Ai and</td><td>£ Γ- ΟΟ</td><td>Ό</td><td> & 1</td>

<td></td><td>a tr ^ · S d FSL ssi la* and</td><td>14.5 (· = 97%) had M3D produced in the sample</td><td>93HRA = 1760Hv and towel ASM id industrial cl SANDVK (204 measured at M3 probably optimistic</td><td>0.088 (measured on the manufactured at _</td><td>about Axis r-</td><td>641 GPa (with ASM subcarrier)</td><td>Axis ABOUT*</td><td>v> <N ABOUT ABOUT</td><td>ob 5 v0 of < s</td><td>sO</td><td>without coating and</td>

<td>Sample no</td><td rowspan="2">Properties and <</td><td>Theory in G / cm theoretical:</td><td>ABOUT Ϊ</td><td>ślij md</td><td>£ p 3</td><td>ABOUT £ “* tri CL, gs • 3</td><td>about about 73</td><td>§ fg .2 ® o</td><td>ot hard material</td><td>and about</td><td>H! AND §P · ^ i 5 H je, GSS ° §</td>

187 539

UP Department of Publications. Circulation of 50 copies Price PLN 4.00

Contents5

57 members in 24 offices

This recordMember, by publication datePriority claim14 more offices are in the list below

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Priority claims
Document	Office	Kind	Date
4688597	United States of America	P	1997-05-13
9809767	United States of America	W	1998-05-13

Members57

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CA2289200A1	Canada	A1	1998-11-19
WO9851419A1	World Intellectual Property Organization (WIPO)	A1	1998-11-19
AU7484698A	Australia	A	1998-12-08
AU7484698A	Australia	A	1998-12-08
NO995498D0	Norway	D0	1999-11-10
WO9851419A9	World Intellectual Property Organization (WIPO)	A9	2000-01-06
NO995498L	Norway	L	2000-01-13
CN1255879A	China	A	2000-06-07
EE9900525A	Estonia	A	2000-06-15
EP1009545A1	European Patent Office (EPO)	A1	2000-06-21
EA199901033A1	Eurasian Patent Organization (EAPO)	A1	2000-06-26
PL336720A1	Poland	A1	2000-07-03
BR9809615A	Brazil	A	2000-07-04
AU725818B2	Australia	B2	2000-10-19
TW413644B	Taiwan Province of China	B	2000-12-01
HU0002738A2	Hungary	A2	2000-12-28
HUP0002738A2	Hungary	A2	2000-12-28
KR20010012570A	Republic of Korea	A	2001-02-15
HK1028368A	Hong Kong, China	A	2001-02-16
HK1028368A1	Hong Kong, China	A1	2001-02-16
HU0002738A3	Hungary	A3	2001-02-28
HUP0002738A3	Hungary	A3	2001-02-28
IL132807A0	Israel	A0	2001-03-19
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CN1077457C	China	C	2002-01-09
US6372346B1	United States of America	B1	2002-04-16
EA002903B1	Eurasian Patent Organization (EAPO)	B1	2002-10-31
UA57080C2	Ukraine	C2	2003-06-16
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US2004052984A1	United States of America	A1	2004-03-18
PL187539B1This record	Poland	B1	2004-07-30
EP1009545A4	European Patent Office (EPO)	A4	2005-03-30
CN1196540C	China	C	2005-04-13
US2006193978A1	United States of America	A1	2006-08-31
KR20070008723A	Republic of Korea	A	2007-01-17
KR100769157B1	Republic of Korea	B1	2007-10-23
KR100813431B1	Republic of Korea	B1	2008-03-14
EP2009124A2	European Patent Office (EPO)	A2	2008-12-31
EP2009124A3	European Patent Office (EPO)	A3	2009-04-22
CA2289200C	Canada	C	2009-08-25
US7632355B2	United States of America	B2	2009-12-15
CZ302016B6	Czechia	B6	2010-09-08
EP1009545B1	European Patent Office (EPO)	B1	2010-12-15
AT491528T	Austria	T	2011-01-15
ATE491528T1	Austria	T1	2011-01-15
DE69842049D1	Germany	D1	2011-01-27
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JP2011168891A	Japan	A	2011-09-01
JP4945814B2	Japan	B2	2012-06-06
JP2014132117A	Japan	A	2014-07-17
EP2009124B1	European Patent Office (EPO)	B1	2014-11-26
ES2526604T3	Spain	T3	2015-01-13

Ductile coat coated hard powders and sinters made of such powders

Abstract

Term

FIG. 2

Q

LOW TOOL FEED RATE LOW TOOL STRENGTH

HIGH TOOL FEED SPEED HIGH TOOL STRENGTH

FIG. 6

Priority claims2

Members57

Numbers

Titles2

Classification