Surface film member, process for rpoducing the surface covering member, cutting tool, and machine tool

(54) Title: FILM FOR SURFACE COATING, SAME PRODUCTION METHOD, CUTTING MACHINE AND MACHINE

TOOL (30) Unionist Priority: 02/22/2007 jp 2007-043030 (73) Holder (s): Mitsubishi Heavy Industries, Ltd.

(72) Inventor (s): Chiaki Yasuda, Ichiro Nagano, Katsunori Akiyama, Masakatsu Fujita, Taiji Kikuchi, Toshiya Watanabe, Toyoaki Yasui, Yukio Komada (74) Attorney (s): Nellie Anne Daniel-Shores (86) International Request: pct JP2008052216 of 05/02/2008 (87) International Publication: W0 2008 / i02663de28 / 08/2008 (57) Summary: film for surface coating, METHOD OF PRODUCTION OF THE SAME, CUTTING TOOL AND MACHINE TOOL. A surface coating film is provided which has a high degree of hardness and excellent resistance to oxidation, and a method of producing it, a cutting tool and a cutting machine. In the surface coating film, an oxidation-resistant layer containing, as a main component, a complex Li oxide and at least Al, is coated on the outer surface of a base material, directly on it or through the intermediary of a layer of high hardness coating. In addition, in a method of producing a surface coating film, the base material as it is or a substance coated with the high hardness coating layer in which a high hardness coating layer is coated on the outer surface of the base material is supported in an airtight container using a support arranged in the container, then a complex oxide forming target formed from Li and at least Al as main components, it is arranged in the container into which oxygen is then fed, and an electrical discharge is produced between the complex oxide-forming target as an anode and the support as a cathode to form an oxidation-resistant layer on the outer surface of the base material or the substance coated with the high hardness coating layer.

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Ρ 0805814 -8 “FILM FOR SURFACE COATING, SAME PRODUCTION METHOD, CUTTING TOOL AND MACHINE TOOL”

Technical area

The present invention relates to a film for surface coating formed in a base material which is a hard material, directly or indirectly on it, a method of producing it, a cutting tool and a cutting machine.

Prior Art

Recently, awareness about environmental problems has been stimulated even in the technical field of cutting, and in particular, environmental adaptability in relation to lubricating oil has become a relevant issue. Accordingly, in order to reduce the harmful influence on the environment, and yet, in view of cost reductions, the need for dry cutting technology that can completely eliminate the need for lubricating oil has been increased.

The merits for a dry cutting process are as follows: the occurrence of environmental problems caused by cutting oil or additives to it can be eliminated, recycling can be facilitated, the costs caused by using the lubricating oil treatment can be reduced, and so on. Meanwhile, since no oil is used for lubrication, the advantages obtained by lubrication, cooling and the like that were obtained by lubricating oil may not be obtained, and severe cutting conditions are necessary.

The technology for forming a coating film that has a high degree of hardness in a base material using a physical vapor deposition process was developed in order to accept dry cutting technology, that is, a coating film from the TiN group, a coating film from the TiAIN group or similar was applied to a tool. However, since the TiN group coating film starts its oxidation at approximately a temperature of 500 ° C while the TiAIN group coating film begins its oxidation at a temperature of approximately 800 ° C, a problem has been raised since these films they cannot be applied to a tool adapted to be used at a high temperature.

Recently, a coating film from the TiAIN group disclosed in Patent Document 1 (Japanese Patent Submitted for Analysis No. H10-25565) was developed, which starts its oxidation at a high temperature in a range from approximately 1,000 ° C to 1,200 ° C, and which can accept cutting conditions under a high temperature.

However, although the TiAIN coating film disclosed in Patent Document 1, can accept the cutting condition under a high temperature, it would soon peel off. In addition, its resistance to oxidation is insufficient if used under a high temperature.

Disclosure of the Invention

Accordingly, in view of the aforementioned problems inherent to the aforementioned technology, an object of the present invention is to provide a film for surface coating that has a greater degree of hardness and an excellent resistance to oxidation, a method of producing it, a tool for cutting and a cutting machine.

For this purpose, according to the present invention, a surface coating film is provided characterized by the fact that an oxidation resistant coating layer composed mainly of a complex Li oxide and at least Al is coated on a surface of a base material which is a hard material, direct to the same or indirect to the same through the intermediate of a high hardness coating layer.

The structure of the surface coating film containing a complex oxide, as a major component, of Li and at least Al can exhibit, in addition to a high degree of hardness and excellent resistance to oxidation, an effect of restricting the rise in temperature , and also exhibit excellent wear resistance since its friction coefficient is small and its heat generation is lower. In addition, in the structure of the surface coating film, the base material is preferably a hard material such as a cemented metal alloy or high-speed steel (also including high-speed tool steel).

In addition, the surface coating film according to the present invention has a high degree of hardness and excellent oxidation resistance, and accordingly, it is preferably used as a coating film material for processing the surface of a tool. or arrays. Thus, it is industrially valuable. In addition, in addition to high degrees of hardness and oxidation resistance, the surface coating film according to the present invention has excellent wear resistance due to high adhesion, and accordingly, is preferably used as a film material. coating for a cutting tool used in a dry cutting process (ie cutting without using cutting fluid).

In addition, the present invention as stated above is characterized by the fact that the oxidation resistant coating layer made of a complex oxide formed in content by Li and another metallic oxide, is coated on the surface of a high hardness coating layer formed in a base material such as the aforementioned hard material.

Furthermore, more preferably, the complex oxide is formed in content by Li and Al, or Li, Al and Mg or Si metal oxide.

In addition, the structure of the surface coating film as stated above is characterized by the fact that the high hardness coating layer contains, in addition to Al, Si, a nitride of at least one type of an element selected from a group consisting of Zr, Hf, Pd, Ir and rare earth elements.

In addition, the structure of the surface coating film is characterized by the fact that the high hardness coating layer still contains, in addition to Al and Si, a nitride of at least one type of element that is both Cr and Ti.

Furthermore, the structure of the surface coating film, as stated above, is characterized by the fact that the thickness A of the oxidation resistant coating layer is not greater than the thickness B of the high hardness coating layer, that is, A &lt;B.

The Li contained in the oxidation resistant coating layer has a high degree of affinity with the nitride contained in the high hardness coating layer, that is, it has a synthesis of a crystalline structure in relation to the nitride. Thus, the adhesion between the oxidation resistant coating layer and the high hardness coating layer is increased, and accordingly, they can hardly peel off from each other.

In addition, the structure of the aforementioned surface coating film is characterized by the fact that an intermediate layer containing at least one of a nitride of at least one type of an element selected from a group consisting of Al, Ti and Cr, a carbide and a carbon nitride is provided between the base material and the high hardness coating film.

With the aforementioned intermediate layer, the adhesion between the base material and the high hardness coating layer becomes greater, and accordingly, the high hardness coating layer can hardly peel, so it is possible to increase the wear resistance of the layer of oxidation resistant coating.

In addition, according to the present invention, a method of producing a surface coating film is provided which comprises the steps of:

support a base material that is a hard material, as it is, or a substance coated with the high hardness coating layer in which the base material is coated on its outer surface with a high hardness coating layer in an airtight container using a support fitted in the container, arrange a complex oxide-forming target formed from Li and at least Al as the main components in the container, feed oxygen into the container, cause an electrical discharge between the target as an anode and the support as a cathode to form an oxidation-resistant surface coating layer on the base material or substance coated with the high-strength coating layer in order to get the film for surface coating.

With this production method, a film for surface coating can be formed that has excellent wear resistance in addition to a high degree of hardness and excellent resistance to oxidation.

In addition, according to the present invention, a cutting tool is provided characterized by the use of a film for surface coating in which an oxidation resistant coating layer composed of, as a main component, a complex Li oxide and minus Al is coated on an outer surface of a basic material tool which is both high-speed steel (or high-speed tool steel) in which metal components including chromium, tungsten, molybdenum and vanadium are added to the steel which is then subjected to a heat treatment such as cooling, such as a cemented metal alloy which is formed by sintering a carbide carbide powder, or on an outer surface of a layer of high hardness coating formed on the tool base material.

Thus, a cutting tool that has a high degree of hardness, excellent resistance to oxidation and excellent wear resistance can be obtained.

In addition, the cutting tool can be used for a machine tool for making a part in a dry cutting process (which is cutting without using cutting fluid), and can preferably be used, in particular, for a machine tool for cutting equipment, where a desired part is manufactured by cutting tool equipment such as a helical cutter, pinion cutter or countersink.

The aforementioned tool cutting machine can be used for a cutting process that requires, for a cutting tool, a high degree of hardness, excellent oxidation resistance and excellent wear resistance, and in particular for a cutting process dry (which is a cutting process without the use of cutting fluid), and accordingly, is excellent in terms of environmental protection and cost.

It is noted that the above configurations can be combined unless it deviates from the concept of the present invention.

As stated above, the surface coating film according to the present invention, with a high degree of hardness and excellent resistance to oxidation, can preferably be used for a tool or dies. In addition, it has a high degree of adhesion in relation to the high hardness coating layer that contains a nitride in order to hardly peel, and, in addition, it has excellent wear resistance, so it is possible to preferably use the film to surface coating for a cutting tool and a tool cutting machine for a dry cutting process in which no cutting fluid is used.

In addition, according to the present invention, a film for surface coating that has excellent wear resistance in addition to a high degree of hardness and excellent resistance to oxidation can be produced.

In particular, according to the present invention, a high degree of hardness and excellent resistance to oxidation can also be obtained by physical vapor deposition, the surface coating film thus obtained can preferably be used as a coating film for treatment surface of a tool and dies, and accordingly, is industrially valuable. In addition, according to the present invention, the surface coating film can have excellent wear resistance due to a high degree of adhesion in addition to a high degree of hardness and a high resistance to oxidation, and accordingly, it can preferably be used not only for the production of a tool and dies, but also for a coating film for a cutting tool for a dry cutting process (which is a cutting process without using cutting fluid).

In particular, it can preferably be used for cutting tool equipment such as a helical cutter, pinion cutter or countersink.

Brief Description of Drawings

Fig. 1 is a schematic sectional view illustrating an embodiment 1 of the present invention;

Fig. 2 is a schematic sectional view illustrating an embodiment 2 of the present invention;

Fig. 3 is a schematic sectional view illustrating an embodiment 3 of the present invention;

Fig. 4 is a schematic view illustrating a coating apparatus for forming an oxidation resistant coating layer on a material or base substance coated thereon with a high hardness coating layer; and \

Fig. 5 is a view to display the results of film forming tests for a comparative example and reference examples 1 to 6, among which as target compositions of a high hardness coating layer (nitride) and a coating layer oxidation resistant (oxide) are changed.

Best Way to Carry Out the Invention

An explanation of the preferred embodiments of the present invention will be made hereinafter. It is noted that as dimensions, the materials, as shapes, as relative and similar positions of the components explained in these modalities should aim at the limit of the technical scope of the present invention unless specifically explained differently, that is, they are merely used for explanation purposes.

(Mode 1)

With reference to Fig. 1 which is a schematic sectional view illustrating an embodiment 1 of the present invention, a film for surface coating in this embodiment has a base material 1 and an oxidation resistant coating layer 2 made of an oxide complex formed in content by Li and another metallic oxide. It is noted that a hard material such as a cemented metal alloy or a high speed steel (or a high speed tool steel) is used as the base material 1.

(Mode 2)

With reference to Fig. 2 which is a schematic sectional view illustrating an embodiment 2 of the present invention, a film for surface coating in the second embodiment is composed of a base material 1 formed on its outer surface with a coating layer of high hardness 3, and an oxidation resistant coating layer 2 coated on the outer surface of the high hardness coating layer 3.

In this configuration, the film thickness of the oxidation coating layer 2 is preferably less than that of the high hardness coating layer 3, but its thicknesses can be configured to be equal to one another in view of various conditions.

(Mode 3)

With reference to Fig. 3 which is a schematic sectional view illustrating an embodiment 3 of the present invention, a film for surface coating in the third embodiment is composed of a base material 1 formed thereon with an intermediate layer 4 containing at least one of a nitride of at least one type of element selected from a group consisting of Al, Ti and Cr, a carbide or a carbon nitride, and a high hardness coating layer 3 formed on the outer surface of the intermediate layer 4, and an oxidation resistant coating layer 2 formed on the high hardness coating layer 3.

In embodiments 2 and 3, the high hardness coating layer 3 and the intermediate layer 4 are preferably formed using a physical vapor deposition process such as high frequency metallization or an ionic coating in order to form the film for surface coating that has a high degree of adhesion and excellent wear resistance.

Fig. 4 is a schematic view illustrating a film forming apparatus for forming the oxidation resistant coating layer on the base material or substance coated with the high hardness coating layer coated on it with the layer of high hardness coating.

The film forming apparatus 10 consists of a compartment 12 which is airtight against atmospheric air, a target 13 arranged on the container roof while a table-like support 17 is located in a chamber 20 of compartment 12. The support 17 is coupled to a motor 18 through the intermediary of a rotating shaft 19 so that support 17 can be rotated in its circumferential direction.

In addition, a DC 11 power source is connected between target 13 and support 17, target 13 being connected to the positive (+) side of power source 11 while support 17 is connected to the negative (-) side of the source of energy 11.

Although only one target 13 is shown schematically in Fig. 4, no less than two targets can be arranged. In this case, no less than two targets 13 can be located in positions that have a distance substantially equal to the support 17.

The vacuum pump 14 is connected to chamber 20 of compartment 12 through the intermediate of a control valve 22 in order to evacuate chamber 20. In addition, an argon gas source 15 is connected to chamber 20 through the intermediate of a valve control 23 in order to feed an inert gas to chamber 20. In addition, an oxygen gas source 16 is connected to chamber 20 through the intermediate of a control valve 24 in order to supply oxygen gas to chamber 20.

In the aforementioned embodiment, the number and types of targets 13 are adjusted according to a type of a layer formed on the material or a base substance 21 coated on it with a high-grade coating layer.

In the film forming apparatus 10, the base material as is, or the substance of the high hardness coating layer 21 in which the high hardness coating layer is formed on the surface of the base material is fitted on the support 17, and the control valves 22, 23 are first opened to supply an argon gas to the chamber 20 while the chamber 20 is evacuated to produce a vacuum.

After completing the vacuum evacuation, when an argon atmosphere is produced in chamber 20, the support 18 is rotated by the engine 18. Then, the control valves 22, 23 are closed, and a DC voltage is applied between the target 13 and the support 17 in order to generate plasma in order to raise the temperature in the chamber 20. When the ambient temperature is set at a constant temperature, the control valve 24 is opened in order to feed oxygen from the oxygen gas source 16 to chamber 20 in order to cause an electrical discharge.

Thus, an oxidation-resistant coating layer is formed on the outer surface of the base material or on the outer surface of the substance on which a base material is covered with a high hardness coating layer. Thus, a surface coating film that has a high degree of hardness, and excellent oxidation resistance and wear resistance is obtained.

The surface coating film in this modality has a single layer structure in which an oxidation resistant coating layer (oxide) is formed in a base material that is a cemented metal alloy (WC), or a multilayer structure in which an oxidation resistant coating layer is formed on the outer surface of a high hardness (nitride) coating layer formed on the base material.

The oxidation resistant coating layer (oxide) is adapted to be formed on the outer surface of the high hardness coating layer (nitride) which is rigid in order to improve its properties such as a friction coefficient and a starting temperature oxidation. In the case of the single layer structure, the oxidation resistant coating layer was brought up to a film thickness of approximately 3 pm, and in the case of the multilayer structure, the oxidation resistant coating layer was brought up to a film thickness. approximately 1 pm in the high hardness coating layer after the latter has been brought to a film thickness of approximately 3.5 pm.

Fig. 5 is a view which shows the results of tests for coatings in a comparative example and in reference examples 1 to 6, among which the target compositions of the oxidation resistant layer (oxide) and the high hardness coating layer hardness (nitride) are changed.

Note that the nitride film was formed in such a way that a compact disk-shaped powder of the nitride material (with a diameter of 50 mm and a thickness of approximately 3 mm) was configured on an AIN target with diameter of 10.16 cm, and a high frequency metallization process was carried out. For the composition of preparation of the compact for the formation of the nitride film, Al_O, 7Zro,₂Si_O, iN which can exhibit a high degree of hardness and a high oxidation starting temperature was used.

The oxide film was formed in such a way that a compact disc-shaped (with a diameter of 50 mm and a thickness of approximately 3 mm) of a powder of the oxide material is configured on a target n of Al2O₃with a diameter of 10.16 cm, and metallization at high frequency was performed. The base material that was used for the formation of the film was cemented metallic alloy (WC) with dimensions of approximately 12 mm x 12 mm x 5 mm.

The metallization nitride compact was produced by molding a mixture of AIN, ZrN and Si material powders₃N₄ which are mixed so as to have a predetermined position, in matrices with an internal diameter of 50 mm. Accordingly, the oxide compact was formed by molding a mixture of powders of LiAIO material₂, MgO, AI₂O₃, Cr₂O₃, SiO₂ and the like which were mixed so as to have a predetermined composition, in matrices with an internal diameter of 50 mm. LiAIO powder₂ was synthesized by the calcination of powders of LiCO material₃ what's up₂O₃ at a temperature of 1,250 ° C for two hours.

In addition, in the reference examples, the mixing ratio of Li and Al to Li9 _xAlyO_z was established to be y / x = 0.9 to 40. If y / x is not greater than 0.9, a single layer of Li₂The possibly was formed, and accordingly, is not preferable.

For example, as in the reference example 7, an oxide layer with a film composition of 1 ^ .sMgo.eAhyOsgj was formed by a metallization process in order to obtain a target composition, (nitride / oxide): (AloyZro ^ Sio .iN / Lio.iyMgoosAh.eo-i) in the reference example 7.

The hardness of the surface coating film formed in this way was measured using a micro Vickers hardness meter under a load condition of 10 g in 10 s.

In addition, the oxidation starting temperature of the surface coating film was determined in such a way that a nitride coating film formed on a Pt plate with dimensions of approximately 12 mm x 5 mm x 0.05 mm was heated in a differential thermal balance (TG-DTA) in order to analyze a temperature at which an increase in weight and in the generation of heat caused by oxidation was initiated. During the TG-DTA analysis, a maximum heating temperature was 1,400 ° C, while a rate of temperature increase was 10 ° C / min. The crystalline structure of the coating film was measured by X-ray analysis.

The testing was carried out using nitride from the AlZrSiN group for a typical nitride layer as a lower layer. In view of the results of the measurements for the hardness and starting temperatures of the oxidation of the surface coating film shown in Fig. 5, it was discovered that the oxidation resistant coating layers each composed of a complex oxide formed in content by a Li oxide and the other metal, (reference examples 1 to 6) were difficult to peel compared to a layer of oxide coating which does not contain Li (comparative example 1).

In addition, in the case of reference example 6 in which Si was added, it was found that the adhesion to the nitride can be increased while the friction coefficient of it is maintained substantially at a value obtained in the reference example

1.

The aforementioned effects can be obtained accordingly by carrying out the oxide coating according to the present invention on a coating film of another nitride such as an Al, Cr or Si nitride or an Al, Ti, Si nitride, i.e. , a coating that has a low coefficient of friction and a long service life can be obtained.

In addition, the oxidation starting temperature is high, that is, for example, 1,310 ° C in reference example 1 and 1,350 ° C in example 2 compared to 1,200 ° C in comparative example 1. Thus, although it is difficult to be oxidized even if the cutting temperature increases, and accordingly, the service life of a cutting tool or similar becomes longer. In addition, the coefficient of friction is low, ie 0.2 in reference example 1 and 0.23 in reference example 2 compared to 0.3 in comparative example 1, and accordingly, the value of heat caused by friction can be decreased. Thus, even if the cutting speed (revolution speed) is increased, the life of a cutting tool can become longer.

In addition, in the reference example 7, the oxidation starting temperature becomes higher, that is, 1,340 ° C. Thus, oxidation can hardly occur even if the cutting temperature increases, and accordingly, the service life of the cutting tool becomes longer. In addition, the coefficient of friction is extremely low compared to 0.3 in comparative example 1, that is, it is 0.164 which is less than 0.2 in reference example 1. In other words, the coefficient of friction in reference example 7 is not greater than 2/3 of the coefficient of friction (0.3) in comparative example 1, that is, approximately 1/2. Thus, in view of such a low coefficient of friction which is comparable to that of boric oxide, a tool coating with a long service life can be provided.

Thus, with the formation of the oxidation resistant coating layer composed of the complex oxide formed in content by a Li oxide and another metal, the oxidation starting temperature can be increased so that oxidation can hardly occur even at a high temperature , and the coefficient of friction is low. Thus, it has been found that the oxidation resistant coating layer can hardly peel. Note that the same result can be obtained even if Cr, Ti, Hf, Pd, Ir and the rare earth elements are used, instead of Zr, in the compound of the group AlZrSiN that a typical example of the nitride layer has been used. that the network constant is not appreciably changed.

Industrial Applicability

According to the present invention, a surface coating layer can be provided which has a high degree of hardness, excellent resistance to oxidation, and which also has excellent wear resistance, and a method of producing it. The surface coating film can also be used for a cutting tool or a cutting machine using your property.