EP0193292A2 — Composite ceramic articles and methods of making …

Claim 1

Independent Claim 265 words

A method for producing a self-supporting ceramic composite structure comprising (1) a ceramic matrix obtained by oxidation of a parent metal to form a polycrystalline material consisting essentially of (i) the oxidation reaction product of said parent metal with a vapor-phase oxidant and, optionally, (ii) one or more non-oxidized constituents of the parent metal; and (2) one or more fillers embedded in said matrix, the method comprising the steps of: (a) positioning said parent metal adjacent to a permeable mass of filler and orienting said parent metal and said filler relative to each other so that formation of said oxidation reaction product will occur in a direction towards and into said mass of filler; and (b) heating said parent metal to a temperature in the range of above its melting point and below the melting point of said'oxidation reaction product to form a body of molten parent metal and reacting the molten parent metal with said oxidant within the said temperature range to form said oxidation reaction product, and in the said temperature range maintaining at least a portion of said oxidation reaction product in contact with and extending between said body of molten metal and said oxidant, to draw molten metal through the oxidation reaction product towards the oxidant and towards and into the adjacent mass of filler so that oxidation reaction product continues to form within the mass of filler at the interface between the oxidant and previously formed oxidation reaction product, and continuing said reacting for a time sufficient to embed at least a portion of the filler within said polycrystalline material.

Claim 2

Independent Claim 265 words

A method for producing a self-supporting ceramic composite structure comprising (1) a ceramic matrix obtained by oxidation of a parent metal to form a polycrystalline material consisting essentially of (i) the oxidation reaction product of said parent metal with a vapor-phase oxidant and, optionally, (ii) one or more non-oxidized constituents of the parent metal; and (2) one or more fillers embedded in said matrix, the method comprising the steps of: (a) positioning said parent metal adjacent to a permeable mass of filler and orienting said parent metal and said filler relative to each other so that formation of said oxidation reaction product will occur in a direction towards and into said mass of filler; and (b) heating said parent metal to a temperature in the range of above its melting point and below the melting point of said'oxidation reaction product to form a body of molten parent metal and reacting the molten parent metal with said oxidant within the said temperature range to form said oxidation reaction product, and in the said temperature range maintaining at least a portion of said oxidation reaction product in contact with and extending between said body of molten metal and said oxidant, to draw molten metal through the oxidation reaction product towards the oxidant and towards and into the adjacent mass of filler so that oxidation reaction product continues to form within the mass of filler at the interface between the oxidant and previously formed oxidation reaction product, and continuing said reacting for a time sufficient to embed at least a portion of the filler within said polycrystalline material.

Claim 3

Dependent Claim 17 words

A method as claimed in Claim 1 wherein the parent metal is titanium, zirconium, silicon or tin.

Claim 4

Dependent Claim 13 words

A method as claimed in Claim 1 wherein the parent metal comprises aluminum.

Claim 5

Independent Claim 20 words

A method as claimed in Claims 1, 2 or 3 including doping the parent metal with at least one dopant.

Claim 6

Dependent Claim 31 words

A method as claimed in Claim 4 wherein the dopant is one or more of magnesium, zinc, silicon, germanium, tin, lead, boron, sodium, lithium, calcium, phosphorus, yttrium, and rare earth metals.

Claim 7

Dependent Claim 20 words

A method as claimed in Claim 4 including doping the parent metal with a combination of at least two dopants.

Claim 8

Dependent Claim 45 words

7• A method as claimed in Claim 6 wherein the said dopants comprise a source of one or both of magnesium and zinc, plus a source of one or more of silicon, lead, tin, germanium, sodium, lithium, calcium, boron, phosphorus, yttrium and rare earth metals.

Claim 9

Dependent Claim 27 words

A method as claimed in Claim 7 wherein the parent metal comprises aluminum and the said dopants comprise a source of magnesium and a source of silicon.

Claim 10

Dependent Claim 18 words

A method as claimed in Claim 4 wherein at least one dopant is alloyed into the parent metal.

Claim 11

Independent Claim 49 words

A method as claimed in any one of Claims 4 to 9 wherein at least one dopant is applied as a layer of dopant onto a surface of the parent metal, and including forming the oxidation reaction product to substantially beyond the depth of the applied layer of dopant.

Claim 12

Independent Claim 26 words

A method as claimed in any one of Claims 4 to 10 including incorporating at least one dopant into at least a portion of said filler.

Claim 13

Dependent Claim 29 words

A method as claimed in Claim 11 including at least a second dopant alloyed with said parent metal or applied to the surface of said parent metal, or both.

Claim 14

Dependent Claim 13 words

A method as claimed in Claim 11 wherein said parent metal comprises aluminum.

Claim 15

Dependent Claim 52 words

A method as claimed in Claim 12 or Claim 13 wherein the dopant comprises a source of one or both of magnesium and zinc, plus a source of one or more of silicon, lead, tin, germanium, sodium, lithium, calcium, boron, phosphorus, yttrium and one or more rare earth metals, and mixtures thereof.

Claim 16

Independent Claim 58 words

A method as claimed in any one of the preceding claims wherein said oxidant is selected from the group consisting of an oxygenrcontaining gas, nitrogen-containing gas, a halogen, sulphur, phosphorus, arsenic, carbon, boron, selenium, tellurium, an H 2 /H 2 0 mixture, methane, ethane, propane, acetylene, ethylene, propylene, and a CO/C0 2 mixture, or compounds or mixtures thereof.

Claim 17

Dependent Claim 15 words

A method as claimed in Claim 15 wherein said oxidant is air at atmospheric pressure.

Claim 18

Independent Claim 58 words

A method as claimed in any one of the preceding claims wherein said parent metal is aluminum, said vapor-phase oxidant is air, said oxidation reaction product is alpha-alumina and said dopant is magnesium, zinc, silicon, lead, tin, germanium, sodium, lithium, calcium, boron, phosphorus, yttrium, one or more rare earth metals, or a mixture of two ore more thereof.

Claim 19

Independent Claim 31 words

A method as claimed in any one of the preceding claims wherein said parent metal is aluminum, said vapor-phase oxidant is a nitrogen-containing gas and said oxidation reaction is aluminum nitride.

Claim 20

Dependent Claim 28 words

A method as claimed in Claim 1 wherein said parent metal is zirconium, said vapor-phase oxidant is a nitrogen-containing gas and said oxidation reaction product is zirconium nitride.

Claim 21

Dependent Claim 28 words

A method as claimed in Claim 1 wherein said parent metal is titanium, said vapor-phase oxidant is a nitrogen-containing gas and said oxidation reaction product is titanium nitride.

Claim 22

Dependent Claim 29 words

A method as claimed in Claim 1 wherein said parent metal is tin, said oxidant is an oxygen-containing gas and said oxidation reaction product is an oxide of tin.

Claim 23

Independent Claim 24 words

A method as claimed in any one of the preceding claims wherein said oxidation reaction product is an oxide, nitride, carbide, boride, or oxynitride.

Claim 24

Dependent Claim 28 words

A method as claimed in Claim 3 wherein said temperature is from about 850°C to about 1450°C and including doping said parent metal with at least one dopant.

Claim 25

Dependent Claim 20 words

A method as claimed in Claim 23 wherein said vapor-phase oxidant is air and said oxidation reaction product is alpha-alumina.

Claim 26

Independent Claim 34 words

A method as claimed in any one of the preceding claims wherein said filler is one which is, or upon said oxidation becomes, substantially thermodynamically stable with respect to said oxidant at said temperature.

Claim 27

Independent Claim 35 words

A method as claimed in any one of the preceding claims wherein said filler comprises one or more single metal oxides of aluminum, cerium, hafnium, lanthanum, neodymium, praseodymium, samarium, scandium, thorium, uranium, yttrium, or zirconium.

Claim 28

Independent Claim 24 words

A method as claimed in any one of Claims 1 to 25 wherein said filler is a binary, ternary, or higher order metallic oxide.

Claim 29

Dependent Claim 18 words

A method as claimed in Claim 27 wherein said metallic oxide is the binary oxide magnesium aluminate spinel.

Claim 30

Independent Claim 27 words

A method as claimed in any one of Claims 1 to 25 wherein said filler is comprised of one or both of carbon fibers and carbon particles.

Claim 31

Dependent Claim 28 words

A method as claimed in Claim 1 wherein said parent metal is aluminum, said vapor-phase oxidant is an oxygen-containing gas, and said oxidation reaction product is aluminum oxide.

Claim 32

Dependent Claim 29 words

A method as claimed in Claim 1 wherein said parent metal is silicon, said vapor-phase oxidant is a carbon compound-containing gas, and said oxidation reaction product is silicon carbide.

Claim 33

Dependent Claim 28 words

A method as claimed in Claim 1 wherein said parent metal is silicon, said vapor-phase oxidant is a nitrogen-containing gas, and said oxidation reaction product is silicon nitride.

Claim 34

Independent Claim 43 words

A method as claimed in any one of Claims 1 to 25 wherein the filler comprises one or more of aluminum oxide, silicon carbide, silicon aluminum oxynitride, zirconium oxide, zirconium boride, titanium nitride, barium titante, boron nitride, silicon nitride, iron-chromium-aluminum alloy, or aluminum.

Claim 35

Independent Claim 44 words

A method as claimed in any one of Claims 1 to 3 or 17 to 24 wherein said filler comprises hollow bodies, particulates, powders, fibers, whiskers, spheres, bubbles, steelwool, plates, aggregate, wires, rods, bars, platelets, pellets, tubes, refractory fiber cloth, tubules, or mixtures thereof.

Claim 36

Dependent Claim 26 words

A method as claimed in Claim 3 or Claim 6 wherein the filler comprises silicon carbide reaction is carried out at a temperature/of at least 850°C.

Claim 37

Dependent Claim 18 words

A method as claimed in Claim 35 wherein said filler comprises a refractory fiber cloth or carbon fiber.

Claim 38

Dependent Claim 41 words

A method as claimed in Claim 4 wherein the parent metal is aluminum and said polycrystalline material further includes an initiation surface of a spinel formed as an oxidation reaction product of said parent ` metal, said dopant and said oxidant.

Claim 39

Dependent Claim 70 words

A self-supporting ceramic composite comprising a ceramic matrix and filler incorporated within said matrix, said matrix comprising an essentially single phase polycrystalline oxidation reaction product and metal channels or voids or both, and characterized by crystal lattice misalignments at oxidation reaction product crystallite grain boundaries less than the lattice misalignments between those neighbouring oxidation reaction product crystallites having planar metal channels or planar voids, or both, disposed between said neighbouring-crystallites.

Claim 40

Dependent Claim 70 words

A self-supporting ceramic composite comprising a ceramic matrix and filler incorporated within said matrix, said matrix comprising an essentially single phase polycrystalline oxidation reaction product and metal channels or voids or both, and characterized by crystal lattice misalignments at oxidation reaction product crystallite grain boundaries less than the lattice misalignments between those neighbouring oxidation reaction product crystallites having planar metal channels or planar voids, or both, disposed between said neighbouring-crystallites.

Claim 41

Dependent Claim 24 words

A composite as claimed in Claim 38 wherein substantially all of said grain boundaries have an angular mismatch of less than about 5 degrees.

Claim 42

Dependent Claim 82 words

A self-supporting ceramic composite comprising a ceramic matrix having filler incorporated therein, said matrix comprising an essentially single phase, polycrystalline oxidation reaction product of interconnected crystallites formed at a temperature below the melting point of said oxidation reaction product upon oxidation of a molten metal precursor, said composite containing a minor portion by volume of metal precursor or voids or both, and having a predominance of substantially arcuate interface boundaries between crystallites and non-oxidized metal, or between crystallites and voids, or both.

Claim 43

Dependent Claim 82 words

A self-supporting ceramic composite comprising a ceramic matrix having filler incorporated therein, said matrix comprising an essentially single phase, polycrystalline oxidation reaction product of interconnected crystallites formed at a temperature below the melting point of said oxidation reaction product upon oxidation of a molten metal precursor, said composite containing a minor portion by volume of metal precursor or voids or both, and having a predominance of substantially arcuate interface boundaries between crystallites and non-oxidized metal, or between crystallites and voids, or both.

Claim 44

Dependent Claim 81 words

A self-supporting ceramic composite comprising a ceramic matrix having filler incorporated therein, wherein said matrix is formed upon oxidation of a molten parent metal precursor with a vapor-phase oxidant and consists essentially of a polycrystalline oxidation reaction product and optionally one or more non-oxidized constituents of the parent metal precursor or voids or both, and is characterized by an essentially single phase, interconnected ceramic matrix skeletal structure, wherein the grain boundaries of said ceramic skeletal structure have no other phase present.

Claim 45

Dependent Claim 81 words

A self-supporting ceramic composite comprising a ceramic matrix having filler incorporated therein, wherein said matrix is formed upon oxidation of a molten parent metal precursor with a vapor-phase oxidant and consists essentially of a polycrystalline oxidation reaction product and optionally one or more non-oxidized constituents of the parent metal precursor or voids or both, and is characterized by an essentially single phase, interconnected ceramic matrix skeletal structure, wherein the grain boundaries of said ceramic skeletal structure have no other phase present.

Claim 46

Dependent Claim 55 words

A self-supporting ceramic composite comprising a ceramic matrix having filler incorporated therein, said ceramic matrix consisting essentially of a single phase polycrystalline, interconnected, inorganic, non-metallic, skeletal structure characterized by grain boundaries devoid of any other phase, and containing metal or voids or both which are interconnected or isolated or both, dispersed through said skeletal structure.

Claim 47

Dependent Claim 55 words

A self-supporting ceramic composite comprising a ceramic matrix having filler incorporated therein, said ceramic matrix consisting essentially of a single phase polycrystalline, interconnected, inorganic, non-metallic, skeletal structure characterized by grain boundaries devoid of any other phase, and containing metal or voids or both which are interconnected or isolated or both, dispersed through said skeletal structure.

Claim 48

Dependent Claim 56 words

A self-supporting ceramic composite comprising a ceramic matrix having filler incorporated therein, said matrix consisting essentially of a single phase, polycrystalline, interconnected, inorganic, non-metallic, skeletal structure, and containing metal or voids or both which are interconnected or isolated or both, dispersed through said skeletal structure, and exhibiting the property of intragranular fracture in said skeletal structure.

Claim 49

Dependent Claim 56 words

A self-supporting ceramic composite comprising a ceramic matrix having filler incorporated therein, said matrix consisting essentially of a single phase, polycrystalline, interconnected, inorganic, non-metallic, skeletal structure, and containing metal or voids or both which are interconnected or isolated or both, dispersed through said skeletal structure, and exhibiting the property of intragranular fracture in said skeletal structure.

Claim 50

Dependent Claim 11 words

A composite as claimed in any one of Claims 38 to

Claim 51

Dependent Claim 9 words

43 and including at least 1% by volume metal.

Claim 52

Dependent Claim 9 words

43 and including at least 1% by volume metal.

Claim 53

Dependent Claim 11 words

A composite as claimed in any one of Claims 38 to

Claim 54

Dependent Claim 16 words

43 wherein said composite contains one or more metals dispersed throughout in primarily an interconnected arrangement.

Claim 55

Dependent Claim 16 words

43 wherein said composite contains one or more metals dispersed throughout in primarily an interconnected arrangement.

Claim 56

Dependent Claim 26 words

A composite as claimed in any one of Claims 38 to 43 wherein said composite contains one or more metals dispersed throughout as substantially non-interconnected inclusions.

Claim 57

Dependent Claim 35 words

A composite as claimed in any one of Claims 38 to 43 wherein said composite contains at least 1% by volume voids dispersed throughout either in primarily an interconnected arrangement or as substantially non-interconnected inclusions.

Claim 58

Dependent Claim 25 words

A composite as claimed in any one of Claims 38 to 43 wherein said metal precursor is aluminum and said oxidation reaction product is alpha-alumina.

Claim 59

Dependent Claim 26 words

A composite as claimed in any one of Claims 38 to 43 wherein said metal precursor is aluminum and said oxidation reaction product is aluminum nitride.

Claim 60

Dependent Claim 26 words

A composite as claimed in any one of Claims 38 to 43 wherein said metal precursor is titanium and said oxidation reaction product is titanium nitride.

Claim 61

Dependent Claim 26 words

A composite as claimed in any one of Claims 38 to 43 wherein said metal precursor is silicon and said oxidation reaction product is silicon carbide.

Claim 62

Dependent Claim 31 words

A composite as claimed in any one of Claims 38 to r 43 wherein said oxidation reaction product is selected from the group consisting of oxides, nitrides, carbides, borides and oxynitrides.

Claim 63

Dependent Claim 56 words

A composite as claimed in any one of Claims 38 to 43 wherein said oxidation reaction product is selected from the group consisting of aluminum oxide, silicon carbide, aluminum oxynitride, zirconium boride, titanium nitride, silicon nitride, and zirconium nitride, titanium boride, silicon boride, hafnium carbide, hafnium boride, titanium carbide, tin oxide, aluminum nitride, and aluminum boride.

Claim 64

Dependent Claim 28 words

A composite as claimed in any one of Claims 40, 43, 44 or 45 wherein said metal precursor is zirconium and said oxidation reaction product is zirconium nitride.

Claim 65

Dependent Claim 26 words

A composite as claimed in any one of Claims 38 to 43 wherein said metal precursor is tin and said oxidation reaction product is tin oxide.

Claim 66

Dependent Claim 23 words

A composite as claimed in Claims 38 to 43 wherein said metal precursor is silicon and said oxidation reaction product is silicon nitride.

Claim 67

Dependent Claim 120 words

A dense, coherent ceramic composite comprised of about 5% to 98% by volume, based on the total volume of the composite, of one or more filler materials contained within a ceramic matrix comprising, based on the total weight of said matrix, about 60% to 99% by weight of interconnected aluminum oxide and about 1% to 40% by weight of an aluminum-containing metallic constituent, and said matrix having an initiation surface of magnesium aluminate spinel which comprises less than 30% by weight of said matrix. 58. A composite as claimed in Claim 57 wherein said filler comprises hollow bodies, particulates, powders, fibers, whiskers, spheres, bubbles, steelwool, plates, aggregate, wires, rods, bars, platelets, pellets, tubes, refractory fiber cloth, tubules, or mixtures thereof.

Claim 68

Dependent Claim 63 words

A dense, coherent ceramic composite comprised of about 5% to 98% by volume, based on the total volume of the composite, of one or more filler materials contained within a ceramic matrix comprising, based on the total weight of said matrix, about 60% to 99% by weight of interconnected aluminum nitride and about 1% to 40% by weight of an aluminum-containing metallic constituent.

Claim 69

Dependent Claim 63 words

A dense, coherent ceramic composite comprised of about 5% to 98% by volume, based on the total volume of the composite, of one or more filler materials contained within a ceramic matrix comprising, based on the total weight of said matrix, about 60% to 99% by weight of interconnected aluminum nitride and about 1% to 40% by weight of an aluminum-containing metallic constituent.

Claim 70

Dependent Claim 42 words

A ceramic composite as claimed in Claim 59 wherein said filler is selected from the group consisting of hollow bodies, particulates, powders, fibers, whiskers, spheres, bubbles, steelwool, plates, aggregate, wires, rods, bars, platelets, pellets, tubes, refractory fiber cloth, tubules, or mixtures thereof.

Claim 71

Dependent Claim 44 words

A composite consisting of (a) one single phase, three-dimensionally interconnected ceramic matrix, (b) one or more metallic constituents and, optionally, voids dispersed and/or extending through said matrix, and (c) one or more fillers embedded in said matrix wherein said ceramic matrix is a nitride.

Claim 72

Dependent Claim 44 words

A composite consisting of (a) one single phase, three-dimensionally interconnected ceramic matrix, (b) one or more metallic constituents and, optionally, voids dispersed and/or extending through said matrix, and (c) one or more fillers embedded in said matrix wherein said ceramic matrix is a nitride.

Claim 73

Dependent Claim 57 words

A composite consisting of (a) one single phase, three-dimensionally interconnected ceramic matrix, (b) one or more metallic constituents and, optionally, voids dispersed and/or extending through said matrix, and (c) one or more fillers embedded in said matrix wherein said ceramic matrix is selected from the group consisting of aluminum nitride, zirconium nitride, titanium nitride, and silicon nitride.

Claim 74

Dependent Claim 57 words

A composite consisting of (a) one single phase, three-dimensionally interconnected ceramic matrix, (b) one or more metallic constituents and, optionally, voids dispersed and/or extending through said matrix, and (c) one or more fillers embedded in said matrix wherein said ceramic matrix is selected from the group consisting of aluminum nitride, zirconium nitride, titanium nitride, and silicon nitride.

Claim 75

Dependent Claim 37 words

A composite as claimed in Claims 61 or 62 wherein said filler comprises hollow bodies, particulates, powders, fibers, whiskers, spheres, bubbles, steelwool, plates, aggregate, wires, rods, bars, platelets, pellets, tubes, refractory fiber cloth, tubules, or mixtures thereof.

Composite ceramic articles and methods of making the same

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