Method of making ceramic articles having channels therein and articles made thereby

The present invention relates generally to ceramic bodies and processes for their manufacture, including bodies of ceramic composite material containing one or more channels which inversely reproduce the geometry of a side-worn metal.

Same Ownership Patent and Patent Application The subject matter of the present application is related to that of the same patent and pending US Patent Applications Serial No. 818,943, filed January 15, 1986 in addition. Serial No. 776,964, filed September 17, 1985, addition of Serial No. 705,787, filed February 26, 1986, addition of Serial No. 591,392, filed March 16, 1984, all in the name of Marc S. Newkirk et al, and entitled New Ceramic Materials and Processes for their manufacture. These patent applications generally describe the discovery of a process for the manufacture of self-supporting ceramic bodies by the use of a special oxidation phenomenon to oxidize a precursor of a medium.

The oxidation reaction may be activated using an alloy contaminant in the parent metal, and provides self-supporting ceramic bodies of the desired size developed as a product of the parent metal oxidation reaction.

Prior oxidation process was improved by the use of external contaminants applied to the surface of the parent metal precursor as described in the same patent pending US Patent Applications Serial No. 822,999 filed January 27, 1986, in addition to Serial No. 776,965, filed September 17, 1985, in addition to Serial No. 747,788, filed June 25, 1985, an addition of Serial No. 632,636, filed July 20, 1984, all in the name of Marc S. Newkirk et al, entitled Processes for Making Self-supporting Ceramic Materials,

The use of the above oxidation processes for the manufacture of self-supporting ceramic bodies by including one or more fillers is described in U.S. Patent Applications Serial No. 819,397, filed January 17 1986, entitled Ceramic Composite Products and Processes for Manufacturing them, which is an addition to Serial No. 697 878, filed February 4, 1985, and entitled Ceramic composite material products and processes for their manufacture, both applications being filed in the name of Marc S. Newkirk et al. These pending patent applications describe a process for producing a body of self-supporting ceramic composite material by developing an oxidation reaction product from a parent metal.

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However, within a permeable mass of filler material, the resulting composite material, however, has no definite or predetermined configuration.

The ability to provide a definite or predetermined configuration to the ceramic body, i.e. the ability to develop a ceramic body of predetermined size and shape, was achieved by infiltrating the filler material with the oxidation reaction product. which forms a shaped preform, that is, by infiltrating the shaped filler to the limits of its surface. This technique is described in U.S. Pat. Serial No. 861,025, filed May 8, 1986 in the name of Marc S. Newkirk et al., entitled Modeled Ceramic Composite Products and Processes for their Manufacturing.

A further development of the foregoing processes allows the formation of self-supporting ceramic structures containing within themselves or several cavities which inversely reproduce the geometry of a positive shaped, precursor parent metal molding enclosed within a bedding material. moldable filler which is at least partially self-binding under specified conditions as described in the same patent pending Serial No. 823 542, filed January 27, 1986, in the name of Marc S. Newkirk et al, entitled Process of the reverse reproduction of form for the manufacture of ceramic composites and products obtained by this process. Yet another development of the above processes allows the formation of self-supporting ceramic bodies with a desirability of

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Negative form inversely reproducing the positive design of a parent metal precursor applied against a mass of filler as described in the pending Serial No. US Patent Application No. 896 157, filed in 13 August 1986, on behalf of Marc S. Newkirk, entitled Process for the manufacture of ceramic composite material with reproduced surface and products obtained by this process. In both of these pending patent applications, the inversely reproduced cavity reproduces the gecmetry of the parent metal.

Full descriptions of all prior patent applications of the same owner, pending, are hereby expressly incorporated by reference.

For certain applications, there is an interest in replacing metals with ceramic products because, for certain properties, ceramic products are superior to metals. There are, however, a number of known limitations or difficulties in making this substitution, such as the versatility of scale reductions, the ability to produce complex shapes, and the like. addressing the characteristics required for end-use application and costs. The inventions presented, patent applications from the same owner described above, overcome many of these limitations or difficulties and provide innovative processes for the reliable production of ceramic materials, including composite materials.

The invention described in the same patent application, Serial No. 823 542 (identified above), alleviates the difficul ...

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formation of ceramic bodies with shapes having complicated internal cavities especially shapes with recurrent cavities. Conventional or known processes for the manufacture of ceramic products of such shapes by compacting or synthesizing D7 particles are not applicable because the internal design necessary to establish the desired geometry of the part cannot be removed with easily after the body is formed around you. While such part geometries can sometimes be prepared by machining the desired shapes from a finished ceramic blank, this solution is rarely used because of prohibitive costs.

SUMMARY OF THE INVENTION

However, the present invention provides another method for producing ceramic bodies with one or more internal channels. Accordingly, the present invention provides a process for producing a self-supporting ceramic body with one or more channels, passages, cavities or the like which inversely reproduces the geometry or design of a shaped wear metal. by oxidizing a parent metal with a solid to form a polycrystalline material consisting essentially of the oxidation reaction product and one or more metal constituents, including constituents of the wearable metal which, upon formation of the ceramic body, are dispersed within said body. In accordance with the process according to the present invention, a set of a shaped or shaped wearable metal and the parent metal are positioned. relative to each other, such that the development or growth of the oxidation reaction product of the parent metal includes at least a portion of the configured wearable metal. The parent metal is heated to a temperature above its melting point but below the melting point of the oxidation reaction product to form a body of the molten parent metal and at that temperature the molten parent metal is reacted. with the oxidant to form the oxidation reaction product. At this temperature, at least a portion of the oxidation reaction product is maintained in contact with and between the molten parent metal body and the oxidizer to progressively extract molten parent metal through the oxidation reaction product and, optionally around the wear metal configured to include it, while the oxidation reaction product continues to form at the interface between the oxidant and the oxidation reaction product previously formed. The reaction proceeds for a time sufficient to include at least a portion of the wear metal formed within the polycrystalline material, and to disperse the wear metal included within the polycrystalline material to form one or more channels that substantially reproduce the geometry of the metal. wearable metal configured.

In another embodiment of the present invention, the above process is modified to produce a self-supporting single or multi-channel ceramic composite body by positioning the parent metal adjacent to a permeable mass of the filler and orienting the parent metal and the material. filling with respect to each other so that the formation of the oxidation reaction product will take place in a sense of the mass of the material. filling material and its interior. In such a case, the wearable metal is configured and supported by the filler material and oxidation reaction product development simultaneously infiltrates the filler material and includes the configured wearable metal that is dispersed in the ceramic composite body. If desired, the configured wear metal may be provided with a coating to protect the wear metal against premature dissolution or premature meltdown, thereby losing the predetermined design or configuration. mined. In addition, a coating may be chosen which upon dispersion of the wearable metal forms a lining on the channel walls, thereby improving the properties of the ceramic body.

In a still further aspect of the present invention there is provided a self-supporting ceramic body or a ceramic port material body having one or more channels which inversely reproduce the geometry of a configured wearable metal and obtained by an oxidation phenomenon of a original metal as described above.

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Another specific aspect of the present invention includes the use as a wear metal of a metal selected from one or more of the following metals: iron, nickel, chromium and alloys or intermetallic posts of one or more of these metals,

In general, the present invention combines with the patent application processes of the same owner with novel concepts for providing single or multi-channel ceramic body formation, including complex interlocking passages, direction changes, tight bends and configurations

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by a technique which reliably permits the inverse reproduction of the approximate dimensions and configuration of a wearable metal model, i.e. a precast structure of the desired configuration made of a metal which can disperse. if within the polycrystalline material consisting of the oxidation reaction product of the parent metal, By dispersion in the polycrystalline material, the wearable metal is allowed to remain, one or more channels which reproduce their former shape inversely. The desired geometries of the openings and internal passages in a ceramic body can be obtained by the techniques according to the present invention much more easily than with conventional solutions or by drilling with drills. , rectification or the like, to obtain the desired shape from a ceramic blank.

As used herein, and in the appended claims, the following terms are defined as follows:

Ceramic should not be misunderstood as limiting itself to a ceramic body in the classical sense, that is, that this body is entirely made of non-metallic and inorganic materials, but rather referring to a body which is predominantly ceramic in regards both composition and dominant properties, although the body may contain minute or substantial amounts of one or more metal constituents derived from the parent metal or reduced from the oxidizing agent or a contaminant dopant, most typically within a range of from about 1% to about 40% by volume. , but may include more metal.

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Oxidation reaction product generally means one or more metals of any oxidation state in which one has given up electrons or shares electrons with another element, compound or combination thereof. Accordingly, an oxidation reaction pipeline according to this definition includes the reaction product of one or more metals with an oxidant as described in this patent application.

Oxidizing means one or more electron acceptors or electron splitters, which may be a solid, a liquid or a gas (vapor) or any combination thereof (i.e., a solid and a gas) under the process conditions.

Original metal means metal, for example aluminum, which is the precursor of the polycrystalline oxidation reaction product and includes such metal as a relatively pure metal, a commercial metal with impurities and / or alloying constituents, or an alloy wherein that metal precursor is the primary constituent; and when mentioning a specific metal as the parent metal, for example aluminum, the identified metal should be considered with this definition in mind, unless otherwise stated. contrary to the context.

Wearable metal means a metal, an intermetallic compound or an alloy which, after being included by the growing polycrystalline oxidation reaction product, disperses into the polycrystalline material to leave a channel that substantially adapts to the dimensions and shape of the space occupied. rather by the wearable metal. It is further understood that the metal depletes ^ |^{| r}

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It may also have any desired configuration or shape, such as hollow bodies, particulate materials, powders, fibers, yarns, beads, bubbles, metal wool, plates, aggregate, rods, bars, sinks, bores, balls, tubes, wire cloth, sponge, tubes or sheets.

Channel or channels is a term used herein to mean a space, a cavity, a passage, etc., unfilled, not necessarily of uniform size, within a mass or body of the appropriate or desired shape, and not limited to a tubular configuration.

BRIEF DESCRIPTION OF DRAWINGS

Fig. 1 is a schematic cross-sectional elevational view showing an assembly of a parent metal precursor and a configured wearable metal disposed next to each other in a bed of particulate filler material, the assembly contained in a refractory vessel.

Fig. 2 is a slightly larger plan view of the parent metal precursor assembly and configured wear metal used in the assembly of FIG. 1, omitting the filler for clarity of representation.

Fig. 3 is a cross-sectional view along line 3-3 of FIG. 1.

Fig. 4 is a larger-scale perspective view of a self-supporting ceramic composite body made from

-11 / Μ of the assembly of fig. 1 and showing in phantom the internal openings comprising a network of passages formed therein.

Figs. 5, 6 and 7 are microphotographs of cross-sectional views of the ceramic composite materials, respectively of Examples 1, 2 and 3.

Fig. 8 is a photograph of a channeled ceramic composite body fabricated by the process according to the present invention with one of the channels illuminated below to illustrate the continuation. of the illuminated canal.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the practice of the present invention, the metal, original and pro. portioned as part of an assembly of an original metal precursor and a configured wearable metal. The wearable metal is molded or shaped to provide the configuration that is to be substantially inversely produced in the form of one or more channels within the ceramic body, preferably a ceramic composite body. In accordance with the practices of the present invention, they may inversely reproduce within the ceramic body shapes ^co™ plexuses such as a network of passages during the formation or development of the ceramic material. The term inversely repro. and used herein to mean that the ceramic body channels obtained by the application of the present invention are defined by internal surfaces of the ceramic body that are virtually congruent with the shape of the configured wearable metal used in the process. 0 configured wearable metal can be modeled

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suitably by any suitable methods or means, for example, suitable metal wires may form a network of wires defining the desired shape, dimensions and location of a network of passageways. Alternatively, a piece of metal, such as a bar, sheet, bar or plate may be suitably machined or drawn to obtain a desired configuration; or the shaped wear metal may be cast, milled, extruded or otherwise shaped to give it a geometry congruent with that desired for the outlets in the ceramic body. Typically, the respective lengths of configured wearable metal elements exceed their respective cross-sectional thicknesses. Accordingly, it is possible to produce ceramic bodies with extremely thin or narrow openings, for example by using a wire as a wearable metal as shown. 0 Configured wearable metal may comprise one or more metal parts suitably molded by one or more processes or means such that when placed within a bed of loading material or otherwise positioned close to the parent metal precursor, the polycrystalline material growth produced by oxidation of the parent metal includes the configured disposable metal and, if present, infiltrates the filler material or at least a portion thereof,

The materials and reaction conditions are chosen such that the polycrystalline material does not grow into the space occupied by the configured wear metal will not occupy that space, but includes the configured wear metal which will then be dispersed in the surrounding polycrystalline material.

Whether the wear material dissolves in, binds with or diffuses into the polycrystalline material or its constituents, or otherwise reacts with the polycrystalline material, resulting in the configured wear metal finally migrating out of space. or volume initially occupied by it, and into the body of polycrystalline material that includes it. This leaves a molded channel that substantially reproduces the geometry of the configured wear metal inversely. The present invention therefore provides the great advantage of allowing the channel geometry to be formed within the ceramic to be established by shaping or working the configured wear metal rather than by drilling or other machining of the ceramic body.

The parent metal precursor may be in any suitable or convenient form, such as ingots, plates, bars or the like, to provide a source of the parent metal. the original metal in any special shape or configuration, provided that sufficient original metal is placed with respect to the wearable metal to include the latter or a portion thereof, within the developing body of polycrystalline material obtained by oxidation of the parent metal. The parent metal may be chosen from aluminum, zirconium, titanium, tin or silicon.

The loading material, optionally used in the practice of the present invention, may be one of a wide variety of materials suitable for this purpose. For example, the mailing material

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The padding may comprise a particulate material such as fine grains of a refractory metal oxide, such as alumina, or may be in the form of tangled fibers or yarns, or in the form of a fiber wool material, for example. ceramic material fibers, the filler material may comprise a combination of two or several geometric configurations, for example, a combination of small grains and particulate fibers It is only necessary that the physical configuration of the filler material is such that it allows the configured wearable metal to be placed on or within a bed or mass of filler material, and that the filler material filler is a material which, under the conditions of the oxidation reaction according to the present invention, as described above, is permeable to passage through the oxidant thereof, when such passage is necessary for contact of the oxidant with the parent metal and development through it of the oxidation reaction product. The filler material must be permeable to the oxidant when a vapor phase oxidant is used to allow it to come into contact with the molten parent metal and the oxide within the mass of filler material.

In the practical application of the process according to the present invention, an assembly of the configured wearable metal and the parent metal precursor is prepared, the configured wearable metal and the base metal adjacent each other. These components may be supported as necessary by any suitable means, such as by supporting the wearable metal configured on or wholly or partially within a bed of filler, the bed of filler may also be

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in contact with the original metal body or partially or totally enveloping the base metal. The optional filler material and the configured wearable metal and the parent metal may perhaps be arranged adjacent to one another without using a filler material. In either case, the assembly is heated to a temperature in the range from a temperature above the melting point of the base metal to a temperature below the melting point of the oxidation reaction product. This heating results in the formation of a body or portion of the ori metal. fused signal, which is exposed to an oxidizing environment at a temperature within the above range. 0 The molten parent metal reacts with the oxidant to form the polycrystalline material comprised of the oxidation reaction product, thereby initiating the inclusion of the configured wearable metal into the developing crystalline powder. At least a portion of the oxidation reaction product is maintained in contact with and between the molten parent metal and the oxidant such that upon continued exposure to the oxidant the molten parent metal is progressively extracted into the product. oxidation reaction and through it, in contact with the oxidant in order to cause the continuous growth of the polycrystalline material in the inter. face between the oxidation reaction product previously formed and the oxidant. As the oxidation reaction product continues to develop it infiltrates the filler material when the filler material is present and includes the configured wearable metal. The process continues until the developing polycrystalline material has included wear metal.

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or a selected portion thereof, which is then diffused into the polycrystalline material.

Polycrystalline ceramic body material produced In accordance with the present invention, in addition to optionally including a filler material included therein, it may include one or more metal constituents, such as non-oxidized constituents of the parent metal or may include spaces voids or both, depending on the conditions under which the oxidation reaction is conducted, the polycrystalline material also contains, at least in the vicinity or area of ​​space originally occupied by the configured wear metal, the wear metal constituents. Typically, in such polycrystalline materials the oxidation reaction product comprises interconnected crystallites, preferably in three dimensions. Metal constituents or inclusions, or voids, may also be at least partially interconnected.

wearable metal may consist of a material whose melting point is about the same as or less than the growth temperature; In such cases, the reproductive fidelity of the wear metals may be impaired due to deformation caused by premature melting or softening of the wear metal configured under the oxidation reaction conditions. However, the adverse effects on the reverse faithful reproduction of the configured expendable £ metal of said_s Nemature melting or softening can be avoided or alleviated if the parent metal is supported by a bed, or by coating the wearable metal configured with a refractory cover. For example, the configured wearable metal may have a fine particle coating of a self-bonding or sintering material adhering thereto so that, upon reaching a high temperature, the cover binds or synthesizes to form a hard crust surrounding the configured wearable metal. . The cover or crust should not be impervious to prevent dispersion of the wearable metal within the oxidation reaction product. The cover may be a cover that reacts with, or is dispersed on, the polycrystalline material or is indisensible thereto.

Any premature softening or melting problem of the configured wearable metal, with the consequent loss of reliability in reverse reproduction of the configured wearable metal, is minimized by using a wearable metal or 1 / g whose melting point is higher. at the temperature at which the oxidation reaction may be carried out efficiently. When using an aluminum parent metal, suitable wear metals with a melting point higher than the temperature at which the oxidation reaction product is formed may include, for example, ferro-chromium aluminum alloys of the type sold under the trademark Fecralloy, Kanthal and Cabot 214, which are respectively registered trademarks of United Kingdom Atomic Energy Authority, KANTHAL CORPORATION and CABOT COMPANY.

In certain cases, it may be desirable to provide you with a channel wall covering to modify or improve the characteristics of the walls. Such a coating can be obtained by covering the configured wearable metal with a suitable material which is then included and integrated into the wax body in the area adjacent the channels formed. Alternatively, a coating that reacts with the original metal may be selected. It is formed to form a compound, such as an oxide, which is then coated with the channels. Under the conditions of the oxidation reaction, the wearable metal supporting the coating disperses in the polycrystalline material and, in the area adjacent to the channels, a lining is developed from the coating material, the coating material is chosen for provide a liner with the desired characteristics, such as corrosion resistance. For example, the configured wear metal may be coated with unreactive particles such as silicon carbide, alumina or the like. The developing polycrystalline material infiltrates the particles and includes the wearable metal and thereby forms for the channel a liner comprising a matrix of polycrystalline material which includes the particles themselves. Alternatively, the configured wearable metal may be coated with a reactive compound such as an Oxide which is reducible by the parent metal. The coating may be applied by forming with the oxide particles a paste with appropriate binder such as an adhesive. one or more coatings may be applied to the configured wear metal to provide the desired thickness. For example, when forming a polycris material. alpha alumina taline obtained by oxidation of an aluminum parent metal in the air, an oxide such as chromium oxide which is reducible by the molten parent aluminum is applied as a coating of a wearable metal such as the alloy Kanthal (iron chromium aluminum alloy). Chromium oxide is apparently reduced to metallic chromium, which disperses in the ceramic body, probably by reaction with one or more metals of the parent metal.

-Ή aluminum sign. Oxidation concomitant with the reduction in chromium oxide forms the alumina, resulting in the channel walls of the ceramic body being substantially coated with alumina. This technique may also be used in conjunction with one or more particulate inert materials, as considered above, for example by mixing chromium oxide and alumina particles and applying a coating of such mixture to the wearable metal. whereas the coating applied to the configured wear metal can be used not only to provide a lining or for the channel walls, but also to introduce one or more components which, as such or as constituents of a reaction product they disperse throughout the ceramic body and are not limited to the zones lining the channel walls.

Referring now to the drawings, fig. 1 shows a refractory vessel (2), such as an alumina vessel, which contains a bed of filler material (4) into which a configured wearable metal (6) is included. Below the plane (XX) is a support bed (8) of a particulate inert material which is not wettable by the parent metal and not impermeable to developing reaction product through itself under process conditions. For example, in the case of the aluminum base metal, which has moderate reaction temperatures, the support bed 8 may comprise Alundum EI particles produced by NORTON COMPANY. Embedded in the bed of filler material (4), and supported by the support bed (8) is a basic metal body (10), the parent metal (10) may be of any suitable shape and as seen in the form. embodiment illustrated by FIGS. 1, 2 and 3 it has a generally rectangular, flat configuration with an upper surface (11), an opposite lower surface (13), and unnumbered side surfaces.

The configured wear metal 6 comprises, in the illustrated embodiment, a set of wear metal wires of circular cross-section. With reference to Figs. 1, 2 and 3, the wire 12 has a washer 15 mounted together. its free end, and the wire 12 has a larger diameter than the wire 14 which, in turn, has a larger diameter than any of the wires 16a, 16b, 16c, 16d ) and (16e) which all have the same diameter. As shown in fig. 3, the wire (14) is arranged substantially parallel to the upper surface (11) in front of it of parent metal (10), as is the case for each of the wires (16a-16e), although only the wire (16a) is visible in fig. The wire 12 is not parallel to the upper surface 11, but is arranged to slope upwardly with respect to the free end of wire 12 to the point wherein he contacts the wire (14). One lifting end of one of the wires (16a-16e) is in contact with the wire (14). The individual wires can be joined together by an appropriate adhesive, a mechanical joint or any metal bonding technique such as tin welding, brazing or usual welding. Alternatively, the wearable metal is configured. (6) I or segments thereof may be cast or otherwise provided as an integrated unit. It will be understood that the shaped wear metal 6 may be produced in any suitable desired shape. For example, one or more of the wires may be bent and the configured wear metal may include or comprise parts.

-21 / V shaped parts such as discs, hubs, cylinders of circular, oval or polygonal section, or shaped parts such as threaded, grooved or toothed components, etc. For example, a coil spring made of a suitable wear metal may be used to form a coil passage within the ceramic body, moldings and helix-wound wires forming loops, rectilines or curves may be combined as desired to create one or more. channels with the desired setting.

assembly of fig. 1 is heated to a temperature within a range sufficiently high to melt the parent metal. ('10) (and to oxidize), but not to melt the configured wearable metal wearable (6) or oxidation reaction product. to form from the original metal. A vapor-phase oxidant crosses the pores of the filler bed (4) and contacts the molten parent metal, within the established temperature range, to oxidize the molten parent metal and develop the oxidation reaction product thereof. For example, when the parent metal is an aluminum parent metal, the oxidation reaction temperature may be from about 80.0 ° C to 1450 ° C, preferably from about 900 ° C to 1350 ° C, and With air or other oxygen-containing gas as oxidant, alpha-alumina results as the oxidation reaction product. The molten base metal is extracted through the oxidation reaction product formed to form a ceramic body extending to the point indicated by the dotted line (5) in FIG. 1. As the reaction proceeds, the configured wear metal (6) is fitted into the polycrystalline material.

The reaction continues until the developing polycrystalline material infiltrates at least a portion of the surrounding filler bed (4) and all or nearly all of the configured wear metal (6). It may be convenient for the distal portions of the wires 12 and 16a-16e inclusive to extend beyond the extent of ceramic body development obtained by oxidation of the parent metal to make visible the location of the wires in the ceramic body. . 0 Wearable metal is dispersed within the polycrystalline material which includes it, thereby migrating from the space previously occupied by the configured wearable metal (6) and leaving a void or channel therein. Without wishing to be bound by any theory or speculation, it appears that the shaped wear metal (6) survives long enough under the oxidation reaction conditions that the developing polycrystalline material is limited to develop around it, so that, after any dispersion of the wearable metal, channels within the ceramic body substantially reproduce the shape of the configured wearable metal (6) or, more precisely, which inversely reproduce the initial shape of the now dispersed configured wear metal (6). The dimensions of each element or portion of the configured wearable metal (.6) are at least approximately congruent with the dimensions of the channels formed within the ceramic body.

Upon completion of the reaction, which desirably occurs after complete oxidation of the parent metal body to prevent the reaction. channel obstruction or channels formed with original metal and the wrapping of the wearable metal configured (6) (and some of the filler material (4)) by the polycrystalline material,

The whole is allowed to cool and the resulting ceramic composite body separated, the dimensions of which are indicated by the dotted line (5) in Figure 1 of any excess filler material left inside the vessel. (2). Such excess filler material or part thereof may form a coherent body in that the filler material or a portion thereof may self-bond at the reaction temperature. However, even if partially sintered the excess filler material can easily be removed from the ceramic composite body by sandblasting, grinding or other analogous process. An economical technique would be to use a sandblast using particles of a material which is suitable as a filler or as a component of the filler as sand so that the removed filler and sand can be reused as a filler. filling in a subsequent operation,

In either case, the ceramic composite body, with the channel (s) formed therein, is machined or ground or otherwise shaped to have a desired outer shape. For example, as illustrated in fig. 4, the ceramic composite body (18) has been machined to form a flattened rectangular block with an upper surface (20), a front face (22) and a rear face (24). Formed within the ceramic composite body (18) are the channels consisting of interconnected circular passages (12).¹), with a cavity (15 ') connected to a distribution passageway (14'1 which in turn is connected to each of a series of discharge passages (16a)).¹), (16b¹), (16c '[, (16d'I and (16e'l, one end of the discharge passages) open on a front face (22J ^and a through end (12'J opens on the face

-24 / posterior (24) of the ceramic body (18). The shape of the various passages is found to inversely reproduce the shape of the des metal. (6), The passages are numbered in the same manner as the individual wires whose shape reproduces inversely, except for the addition of a single. 0 The ceramic body (18) therefore comprises a product well adapted to serve as a fluid border or dispenser introduced through the passageway (12 ') and dispersed through the passageways (16a).¹ £ a (16e ')'. The passages are positioned and precisely sized without the need to drill holes through the ceramic body (18). Instead of developing the ceramic body to a coarse shape and then machining it to a finished external configuration, the ceramic body can be developed to a desired size and shape by appropriate techniques, such as using a filler material. molded as a preform, as described in detail in the above-identified patent application of the same owner, Serial No. 861,025. These techniques avoid the need for extensive machining or grinding of the ceramic body.

When desired the ceramic body may be developed to completely include the wearable metal pattern, thus no open channel forming for an exterior surface. The ceramic product may be opened, that is, it may be cut, worn, fragmented, machined, etc., in order to connect or expose at least one of the channels to the surface.

A self-supporting ceramic composite body manufactured according to the present invention and suitable for use as a

A discharge flange of a fluid such as a spinneret, a metering jet or other similar product for regulating or distributing the flow or passage of a fluid such as a liquid, a gas, a molten metal, a polymer, a resin, etc. As used herein and in the claims the term "nozzle for discharging a fluid" means in a broad sense any kind of nozzle, such as atomized or liquid discharge nozzles, extrusion nozzles, nozzles such as those used in blowing fibers or filaments in or braiding synthetic fibers or filaments, etc., and spinning plate, means a specialized nozzle commonly used for spinning glass fibers or fused synthetic organic polymer fibers. The wearable metal is shaped and positioned in the filler material in accordance with the desired configuration and dimensions for the channel or channels which will include the fluid flow path. 0 The channel or channels formed in the ceramic body are configured to have an inlet and an outlet, ensuring the wearable metal so that the channels or channel formed are accessible from one or more surfaces of the ceramic composite body. or by opening after the process of the composite body which has formed the channels or channel therein to gain access to one or more of the channels. By opening the ceramic body is meant any machining, cutting, grinding, drilling, fragmentation or similar operations in the ceramic body to provide access to one or more channels. The present invention allows the manufacture of ceramic composite products having an intricate path for a fluid. For example, a product can be manufactured as described above which combines a number of inlet channels with few · Single or single outlet channels or, conversely, a product that splits the input stream from a single inlet channel to multiple outlet channels such as a fuel injector for an internal combustion engine, or a spinning plate suitable for extruding polymeric fibers. Also, by specifically configuring the dimensions of the wearable metal, an intricate flow path can be established between the inlet and outlet channels, which provides, for example, a mixing chamber for mixing separate fluids supplied to the channel by a multitude. of input channels.

While specific embodiments of the present invention have been described in detail with specific reference to aluminum as the parent metal, other parent metals that meet the criteria of the present invention include, but are not limited to, silicon, titanium, tin, zirconium and hexamide. For example, specific embodiments of the present invention include, when aluminum is the parent metal, alpha-alumina or aluminum nitride as the oxidation reaction product; titanium as the parent metal and titanium nitride as the oxidation reaction product; silicon as the parent metal and silicon carbide as the oxidation reaction product.

A solid, liquid or vapor phase oxidant may be used. however, or a combination of such oxidants, for example, typical oxidants include, without limitation, oxygen, nitrogen, a halogen, sulfur, phosphorus, arsenic, carbon, boron, selenium,

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tellurium and compounds or combinations thereof, for example silica (as an oxygen source), methane, ethane, propane, acetylene, ethylene and propylene (as carbon sources) or mixtures such as air, H ^ / H ^ O and CO / CO ^ 'being the last two (ie H ^ / H ^ O and CO / CO ^). usable for reducing the oxygen activity of the environment. Accordingly, the ceramic structure according to the present invention may comprise an oxidation reaction product which comprises one or more of oxides, nitrides, carbides, borides and oxinitrides, among others. More specifically, the oxidation reaction product may be one or more of aluminum oxide, aluminum nitride, silicon carbide, silicon boride, aluminum boride, titanium nitride, zirconium nitride. , titanium boride, zirconium boride, zirconium carbide, silicon nitride, molybdenum silicon, titanium carbide, hafnium carbide, ammonium boride and tin oxide.

While specific embodiments of the present invention have been described with reference to the use of vapor phase oxidants, any suitable oxidants may be used. If a gaseous or vapor oxidant is used, i.e. a vapor phase oxidant in the manufacture of a ceramic body that includes a filler material, the filler material used and a material that is permeable to the vapor phase oxidant. so that by exposing the filler bed to the oxidan · ?. Accordingly, the vapor phase oxidant crosses the pores of the filler bed to come into contact with the molten original in it.

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"Steam" means a vaporized or normally gaseous material which provides an oxidizing atmosphere, preferably at atmospheric pressure. For example, oxygen or oxygen-containing gas mixtures (including air) are preferred vapor phase oxidants, for example where aluminum is the parent metal and aluminum oxide is the desired reaction product, with air being usually more preferred. for obvious reasons of economy. When an oxidant is identified as containing or comprising a specific gas or vapor, it means an oxidant wherein the identified gas or vapor is the predominant or at least significant ionic oxidant to the parent metal under the conditions obtained in the oxidizing environment used. For example, although the main constituent of air is nitrogen, the oxygen content of air will be the only oxidant to the parent metal, because oxygen is an oxidant, much stronger than nitrogen. falls under the definition of oxygen-containing gaseous oxidant, but not that of nitrogen-containing gaseous oxidant. An example of a nitrogen-containing gaseous oxidant is the forming gas, which typically contains 9.6 percent nitrogen by volume, 4 percent hydrogen by volume.

When a solid oxidant is used, it is usually dispersed throughout the bed of filler or through a portion of the bed adjacent to the parent metal, in the form of a particulate material mixed with the filler, or perhaps as a coating on the filler. filler particles. Any suitable oxidant including elements such as boron or carbon or reducible compounds such as silicon dioxide or certain stability borides may be used.

-29 / lower thermodynamics than boride reaction product with the parent metal. For example, when using silica as a solid oxidant for an aluminum parent metal, the resulting oxidation reaction product is alumina.

In certain cases, the oxidation reaction may proceed so rapidly with a solid oxidant that the oxidation reaction product tends to melt due to the exothermic nature of the process. This occurrence can degrade the microstructural uniformity of the ceramic body. This isothermal reaction may be prevented or moderated by mixing in the composition substantially inert filler materials which have a low reactivity. An example of such a suitable filler is a material that is identical to the desired oxidation reaction product.

If a liquid oxidizer is used, the entire bed of the filler material or a portion thereof adjacent to the molten metal and impregnated with the oxidant. Reference to a liquid oxidant means an oxidant that is liquid under the oxidation reaction conditions, so that a liquid oxidant may have a solid precursor, such as a salt which is fused under the oxidation reaction conditions. Alternatively, the liquid oxidant may be a liquid precursor, for example a solution of a material which is used to impregnate a portion or all of the filler material, for example by dipping, and which melts or decomposes under the reaction conditions. oxidation to provide an appropriate oxidizing moiety. Examples of liquid oxidants as defined herein include low melting glasses.

300 filler material, when used, may comprise either a single material or mixture of two or more materials and furthermore not disperse into the polycrystalline material. An appropriate class of filler materials include chemical species which, under the process temperature and oxidation conditions, are nonvolatile, thermodynamically stable and do not react with or dissolve the molten parent metal. Numerous materials are known to those skilled in the art to meet such criteria: for example, where an aluminum original is used and air or oxygen as oxidant, such materials include the simple metal oxides of:

aluminum, Al? Og; calcium, CaO; cerium, CeO₂hafnium HfQ₂; lantane,

There₂0₃; lithium, Li2 O; magnesium, MgO; Neodymium, Nd₂0₃praseodymium, various oxides; Samarium Sm₂0₃scandium, nio, u0₂; Yttrium Y₂0₃; and zirconium, Zr0₂·

Sc o₃; Tory T0₂; In addition, a large number of binary, ternary, and higher order metal compounds, such as magnesium aluminate spinel, Mg0.Al₂0₃, is contained in this class of stable refractory compounds.

A second class of suitable shell material or filler material components are those intrinsically stable in the oxidizing environment and the high temperature of the preferred embodiment, but which, due to the relatively slow kinetics of degradation reactions, can be incorporated as a phase of filler material within the developing ceramic body. An example is silicon carbide. This material would completely oxidize under the conditions necessary to oxidize aluminum with oxygen or air according to the present invention if it were not a silicon oxide protective layer

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m covering the silicon carbide particles to limit further oxidation of silicon carbide. The silicon carbide protective layer also allows the silicon carbide particles to sinter or bond to each other and to the other components of the filler material.

A third class of suitable filler materials is materials such as carbon fibers which, by reason of the nature of the filler. Thermodynamic or kinetic reactions would not be expected to survive in the oxidizing environment necessary for carrying out the present invention or exposure to the molten metal implied in the preferred embodiment, but which may become compatible with the process of the present invention. if 1 [becomes the least active environment, for example through the use of^or CO / COg as oxidizing gases, or 2) by applying a coating thereon, such as aluminum oxide, which makes the filler kinetically unreactive in the oxidizing environment or in contact with the parent metal.

As explained in the patent applications of the same owner, the contaminant materials used in conjunction with the parent metal may in certain cases beneficially influence the oxidation reaction process, especially in systems^nowhich use aluminum as the parent metal. The function or functions of a contaminating material may depend on a number of factors other than the contaminating material itself. Such factors include, for example, the particular combination of contaminants, when two or more contaminants are used, the use of an externally applied contaminant in combination with a contaminant.

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alloying agent of the parent metal, the concentration of the contaminant, the oxidizing environment and the process conditions.

Contaminant or contaminants used in conjunction with the parent metal (1) may be provided as alloying constituents of the parent metal, (2) may be applied to at least a portion of the parent metal surface, or (3f may be applied in part or in or incorporated into all filler or preform material, or any combination of two or more of the techniques (1), (2) and (3J) may be used. For example, an alloyed contaminant may be used alone or in combination with a second externally applied contaminant. In the case of technique (3), in which one or more additional colorants are applied to the filler material, the application may be in any suitable manner, as explained in the patent applications of the same owner.

Contaminants which may be used for an aluminum parent metal, in particular air as an oxidizer, include magnesium, zinc, silicon, either alone or in combination with each other or in combination with other contaminants, as described below. Such metals, or a suitable source of such materials, may be used as alloying elements in the parent aluminum base metal, with concentrations of about 0.1 to 10 each for each. percent by weight based on the total weight of the resulting contaminated metal. Such contaminating materials or an appropriate source thereof, for example, MgO, ZnO, or Si0₂»Can be used externally to the original metal. Thus, an alumina ceramic structure can be obtained for an alloy of

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aluminum-silicon as parent metal, using air as oxidant using MgO as surface contaminant, in an amount greater than about 0.0008 grams per gram of the parent metal to be oxidized and greater than about 0.003 grams per square centimeter of the metal surface. to which MgO applies.

Other examples of air-oxidized efficient aluminum parent metal contaminating materials include sodium, germanium, tin, lead, lithium, calcium, boron, phosphorus and yttrium, which may be used individually. or in combination with one or more contaminants, depending on the oxidant and the process conditions. Rare earth elements such as cerium, lanthanum, praseodymium, neodymium and samarium may also be used as contaminants and here only once, especially when used in combination with other contaminants. All contaminant materials, as explained in the patent applications of the same owner, are effective in promoting the development of the polycrystalline oxidation reaction product for aluminum-based parent metal systems.

The ceramic composite structure obtained in the practical embodiment of the present invention will usually be a dense, coherent mass in which from about 5% to about 98% by volume of the total volume of the composite structure, excluding the channels, is consisting of one or more of the filler components fitted within a polycrystalline matrix material. The polycrystalline matrix material is usually constituted, when the parent metal is aluminum, of more or

60% plus or minus 98% by weight (by weight of polycrystalline material) of interconnected alpha-alumina oxide and about 1 to 40% by weight (on the same basis) of constituents rusty parts of the original metal and wearable metal.

The following examples exemplify the practice of certain aspects of the present invention.

EXAMPLE 1

A ceramic composite body according to the present invention was fabricated so as to have a helical channel incorporated within its structure. The wear metal employed was a commercially available metallic wire (Kanthal A of KANTHAL CORPORATION having a alloy composition, by weight 5% AI, 22% Cr, 0.5% Co, the remainder Fe, melting point of approximately 1510 ° C and measuring 0.8 mm (0.0.32 µm in diameter) A string of yarn described above was wound into a coil approximately 25.4mm (1) long and 22.2mm ( 7/8 in diameter The coil was heated in an oxygen atmosphere at 1200 ° C for 36 hours to develop an oxide coating on its surface. 0 The coiled cord was removed and placed around a 380.1 aluminum alloy cylindrical ingot (from BELMONT METALS, having a nominal specification by weight of 8 to 8.5% Si to 2 to 3% Zn and 0.1% Mg as active contaminants and 3.5% Cu as well as Fe, Mn and Ni, the remainder being AI, but we found that the Mg content was sometimes higher, for example in 0.17% to 0.18% / .0 ingot averaged 25.4 mm (11.2 in length and 22.2 mm (7/8 / in diameter) so

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The bill began at one end of the ingot and ended at the other end. The ingot wrapped in the coil was placed in a bed of the alumina filler material (NORTON CO. Aluminandum 38, 90 mesh size) contained in a refractory vessel so that a circular face of the ingot protrudes slightly above bed of the filling material. A layer of alumina particles (NORTON's Alundum EI, 90 mesh size) were placed which were substantially refractory at process temperature relative to the inclusion of the alumina oxidation reaction product in the filler bed. to cover the exposed surface of the ingot. This set was placed in an oven and heated for five hours at 1050 ° C. The oven temperature was maintained at 1050 ° C in air for 48 hours and cooled again for another five hours. The assembly was removed from the oven and the ceramic composite body, which comprises the product of the aluminum oxidation reaction, was recovered by fitting constituents of the filler bed. 0 The excess of the uncapped filler material was removed from the surface of the composite product, and the composite body was cut transversely to reveal the developed or coiled channel with the geometry of the wearable metal coil. Fig. 5 The micrograph of the cross-section of the ceramic composite at 100 times magnification. As seen in the figure, the wearable metal was dispersed only from its original position, thus forming the channel. 0 The resulting channel diameter measured 0.89 mm (0.035). · The slight difference measured in the diameter of the wearable metal wire and the diameter of the formed channel is attributed to the difference between the dilatation

-36/ /

thermal insulation of the metal wire, which occurs on heating and the thermal contraction of the composite body during cooling.

EXAMPLE 2

A ceramic composite body according to the present invention has been fabricated to have four substantially parallel channels incorporated into its structure. The wearable metal used comprised four strands of nickel wire (99.9975% pure, having a melting point of 1453 ° C), measuring approximately 10 cm (4^no) in length and 1 mm in diameter. A bar of the same aluminum alloy 380.1 as used in example 1 was placed and measuring 11.4 cm (4 1/2) in length by 5.08 cm (2J in width, by 17.2 mm (1 / 2) thick, on a bed of the same refractory alumina particles (Alundum EI of NORTON, 90 mesh) used in example 1, so that a face of 11.4 cm (4 1/2) by 5.08 cm (2) was exposed to the atmosphere and substantially aligned with the refractory bed. Put up | a layer approximately 6.35 mm (1/4) deep of the alumina terial πμ (NORTON Alundum 38, 9Q mesh) on the upper surface of the exposed aluminum alloy surface. The four nickel metal wires are substantially parallel to each other at the top of the filler layer so that they are approximately parallel to the 11.4 cm (4 1/2) by 5.0.8 cm (2) surface. of the underlying bar of the aluminum alloy, and equidistant from it. The yarns were then covered with a layer of the same alumina filler (Alundum 38). This combined set was placed in an oven and heated

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air for five hours at 1080 ° C. The oven temperature was maintained at 1080 ° C for 48 hours, and cooled for a period of five hours. The whole was removed from the oven, and the resulting ceramic composite body, which comprises the alumina oxidation reaction product, was recovered by fitting constituents of the alumina filler material. 0 The rectified ceramic composite was cut transversely to illustrate the channels formed by replacing the nickel metal wires. Fig. 6 is a photograph of the cross-sectional composite body illustrating the four parallel channels within its structure. The diameter of a channel was measured, being 1.06 mm.

EXAMPLE 3

The same assembly and method as described in Example 2 was used except that the wearable metal wires consisted of the Kanthal A material used in Example 1, coating its surface with a layer of Cr 2 O 4 (mixed with polyvinyl alcohol to It was used as a vehicle of application and then layered and then coated with a mixture of colloidal silica and alumina particles (Alundum 38 from NORTON CO. 500 mesh size 500 mesh). The assembly was heated by observing the same cycle as described in Example 2, and the resulting composite was recovered. The resulting composite was sectioned transversely to reveal the formed channels. Fig. 7 is a 50 times enlarged microphotograph showing one of the channels formed by the substantial exhaustion of the wearable metal from its original position. In addition, the photomicrograph shows the annular lining that is substantially concentric with the channel resulting from the coating. By analysis of the liner under the scanning electron microscope

F '·

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The coating was substantially alumina. The diameter of the channel shown in FIG. 7 media 0.89 mm (0.035),

EXAMPLE 4

Example 2 was again used except that the four wearable metal wires used were a nickel-chromium aluminum superalloy (Cabot 214 from CABOT CORPORATION with an alloy composition by weight of 16% Cr, 4.5% Al, 2% Co, 2.5% Fe, 0.5% Mo, 0.5% W 0.05% C, 0.02% I, 0.01% B and the remainder Ni, and with a melting point of approximately 1345 ° C_Ç). The assembly was placed in an oven and heated for five hours at 1050 ° C. The oven temperature was maintained at 1050 ° C for 72 hours, and then cooled for five hours. The ceramic composite was removed and cut transversely to illustrate the substantially exhausted channels of the wearable metal wires from their original and dispersed position within the composite structure. Fig. 8th and a photograph of the cross-cut ceramic composite product, with a light source arranged beneath one of the formed channels, to illuminate it and to show therein. light channel,

Although only a small number of embodiments, as examples, of the present invention have been described in a minor way, those skilled in the art will readily understand that the present invention encompasses many combinations and variants beyond those exemplified.