EP0245193A2 — Method of making shaped ceramic composites with t…

Claim 1

Independent Claim 214 words

A method for producing a self-supporting ceramic body by oxidation of a parent metal to form a polyerystal- line material consisting essentially of (1) the oxidation reaction product of said parent metal with an oxidant including a vapor-phase oxidant, and, optionally, (2) one or more metallic constituents, said method comprising the steps of: (a) providing at least a portion of said parent metal with a barrier means at least partially spaced from said parent metal for establishing at least one surface of the ceramic body; (b) heating said parent metal to a temperature above its melting point but below the melting point of the oxidation reaction product to form a body of molten metal, and at-said temperature (i) reacting said molten metal with said oxidant to form said oxidation reaction product, (ii) maintaining at least a portion of said oxidation reaction product in contact with and between said molten metal and said oxidant, to transport molten metal through the oxidation reaction product towards said barrier means and into contact with said oxidant so that oxidation reaction product continues to form at the interface between the oxidant and previously formed oxidation reaction product, and (iii) continuing said reaction to said barrier means to produce said ceramic body having said surface established by said barrier means.

Claim 2

Independent Claim 214 words

A method for producing a self-supporting ceramic body by oxidation of a parent metal to form a polyerystal- line material consisting essentially of (1) the oxidation reaction product of said parent metal with an oxidant including a vapor-phase oxidant, and, optionally, (2) one or more metallic constituents, said method comprising the steps of: (a) providing at least a portion of said parent metal with a barrier means at least partially spaced from said parent metal for establishing at least one surface of the ceramic body; (b) heating said parent metal to a temperature above its melting point but below the melting point of the oxidation reaction product to form a body of molten metal, and at-said temperature (i) reacting said molten metal with said oxidant to form said oxidation reaction product, (ii) maintaining at least a portion of said oxidation reaction product in contact with and between said molten metal and said oxidant, to transport molten metal through the oxidation reaction product towards said barrier means and into contact with said oxidant so that oxidation reaction product continues to form at the interface between the oxidant and previously formed oxidation reaction product, and (iii) continuing said reaction to said barrier means to produce said ceramic body having said surface established by said barrier means.

Claim 3

Independent Claim 269 words

A method for producing a self-supporting ceramic composite structure comprising a mass of filler material infiltrated by a ceramic matrix obtained by the oxidation of a parent metal to form a polycrystalline matrix material, said polycrystalline matrix material consisting essentially of (1) the oxidation reaction product of said parent metal with one or more oxidants including a vapor-phase oxidant and, optionally, (2) one or more metallic constituents, said method comprising the steps of: (a) heating said parent metal to a temperature above its melting point but below the melting point of the oxidation reaction product to form a body of molten metal, (b) contacting a zone of said mass of filler material with said body of molten metal, said mass of filler material having at least one surface defined by a barrier means at least partially spaced from said contacting zone such that formation of said oxidation reaction product will occur into said mass of filler material and in the direction toward said barrier means, and at said temperature (i) reacting said molten metal with said oxidant to form said oxidation reaction product, (ii) maintaining at least a portion of said oxidation reaction product in contact with and between said molten metal and said oxidant, to progressively transport molten metal through the oxidation reaction product toward the oxidant so that oxidation reaction product continues to form at the interface between said oxidant and previously formed oxidation reaction product that has infiltrated said mass of filler material, and (iii) continuing said reaction to said barrier means to produce said ceramic composite structure having said surface established by said barrier means.

Claim 4

Independent Claim 269 words

A method for producing a self-supporting ceramic composite structure comprising a mass of filler material infiltrated by a ceramic matrix obtained by the oxidation of a parent metal to form a polycrystalline matrix material, said polycrystalline matrix material consisting essentially of (1) the oxidation reaction product of said parent metal with one or more oxidants including a vapor-phase oxidant and, optionally, (2) one or more metallic constituents, said method comprising the steps of: (a) heating said parent metal to a temperature above its melting point but below the melting point of the oxidation reaction product to form a body of molten metal, (b) contacting a zone of said mass of filler material with said body of molten metal, said mass of filler material having at least one surface defined by a barrier means at least partially spaced from said contacting zone such that formation of said oxidation reaction product will occur into said mass of filler material and in the direction toward said barrier means, and at said temperature (i) reacting said molten metal with said oxidant to form said oxidation reaction product, (ii) maintaining at least a portion of said oxidation reaction product in contact with and between said molten metal and said oxidant, to progressively transport molten metal through the oxidation reaction product toward the oxidant so that oxidation reaction product continues to form at the interface between said oxidant and previously formed oxidation reaction product that has infiltrated said mass of filler material, and (iii) continuing said reaction to said barrier means to produce said ceramic composite structure having said surface established by said barrier means.

Claim 5

Independent Claim 284 words

A method for producing a ceramic composite body of desired shape comprising a preform infiltrated by a ceramic matrix obtained by oxidation of a parent metal to form a polycrystalline matrix, said polycrystalline matrix consisting essentially of (1) the oxidation reaction product of said parent metal with one or more oxidants including a vapor-phase oxidant and, optionally, (2) one or more metallic constituents, said method comprising the steps of: (a) heating said parent metal to a temperature above its melting point but below the melting point of the oxidation reaction product to form a body of molten metal, (b) providing a shaped preform having at least one surface defined by a barrier means, said preform being permeable to infiltration by said oxidation reaction product, (c) contacting a zone of said preform with said body of molten metal with said surface of said preform spaced from said contacting zone such that formation of said oxidation reaction product will occur into said preform and in the direction toward said surface, and at said temperature (i) reacting said molten metal with said oxidant to form said oxidation reaction product, (ii) maintaining at least a portion of said oxidation reaction product in contact with and between said molten metal and said oxidant, to progressively transport molten metal through said oxidation reaction product toward the oxidant so that oxidation reaction product continues to form at the interface between said oxidant and previously formed oxidation reaction product that has infiltrated said preform, and (iii) continuing said reacting until said polycrystalline matrix has infiltrated said preform to said barrier means to produce said ceramic composite body and having a configuration of said preform and said surface established by said barrier means.

Claim 6

Independent Claim 284 words

A method for producing a ceramic composite body of desired shape comprising a preform infiltrated by a ceramic matrix obtained by oxidation of a parent metal to form a polycrystalline matrix, said polycrystalline matrix consisting essentially of (1) the oxidation reaction product of said parent metal with one or more oxidants including a vapor-phase oxidant and, optionally, (2) one or more metallic constituents, said method comprising the steps of: (a) heating said parent metal to a temperature above its melting point but below the melting point of the oxidation reaction product to form a body of molten metal, (b) providing a shaped preform having at least one surface defined by a barrier means, said preform being permeable to infiltration by said oxidation reaction product, (c) contacting a zone of said preform with said body of molten metal with said surface of said preform spaced from said contacting zone such that formation of said oxidation reaction product will occur into said preform and in the direction toward said surface, and at said temperature (i) reacting said molten metal with said oxidant to form said oxidation reaction product, (ii) maintaining at least a portion of said oxidation reaction product in contact with and between said molten metal and said oxidant, to progressively transport molten metal through said oxidation reaction product toward the oxidant so that oxidation reaction product continues to form at the interface between said oxidant and previously formed oxidation reaction product that has infiltrated said preform, and (iii) continuing said reacting until said polycrystalline matrix has infiltrated said preform to said barrier means to produce said ceramic composite body and having a configuration of said preform and said surface established by said barrier means.

Claim 7

Dependent Claim 31 words

- 4. The method according to Claims 1, 2 or 3 wherein said barrier means on contact with transported molten parent metal is substantially nonwettable by said transported molten parent metal.

Claim 8

Independent Claim 40 words

The method according to Claims 1, 2 or 3 wherein said barrier means on contact with transported molten metal reacts with said transported molten parent metal to substantially impede transport of said molten parent metal through said oxidation reaction product.

Claim 9

Independent Claim 38 words

The method according to Claims 1, 2 or 3 wherein said barrier means is selected from the group consisting of calcium sulfate, calcium silicate, portland cement, tricalcium phosphate, or mixtures thereof, and optionally includes silica and calcium sulfate.

Claim 10

Dependent Claim 24 words

The method of Claim 6 wherein said barrier means additionally includes a volatilizable material to render said barrier means permeable under the process conditions.

Claim 11

Dependent Claim 13 words

The method of Claim 6 wherein said barrier means additionally includes a filler.

Claim 12

Dependent Claim 29 words

The method of Claim 8 wherein said filler is in particulate form and has substantially the same coefficient of expansion as that of said filler material or said preform.

Claim 13

Dependent Claim 13 words

The method of Claim 8 or Claim 9 wherein said filler is alumina.

Claim 14

Independent Claim 20 words

The method according to Claims 1, 2 or 3 wherein said barrier means comprises stainless steel or a dense ceramic.

Claim 15

Independent Claim 27 words

The method according to Claims 1, 2 or 3 wherein said parent metal is selected from the group consisting of aluminum, silicon, titanium, tin, zirconium and hafnium.

Claim 16

Independent Claim 43 words

The method according to Claims 2 or 3 wherein said oxidant includes at least one of a solid bxidant or a liquid oxidant or a combination of a solid oxidant and a liquid oxi- dant, incorporated into said filler material or said preform.

Claim 17

Dependent Claim 20 words

The method of Claim 12 wherein solid oxidant is selected from the group consisting of silica, boron and reducible borides.

Claim 18

Independent Claim 56 words

The method according to Claims 1, 2 or 3 wherein said oxidant is selected from the group consisting of an oxygen-containing gas, a 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, silica and a CO/CO 2 mixture, or mixtures thereof.

Claim 19

Dependent Claim 21 words

The method of Claim 3 wherein said preform includes materials selected from the group consisting of silica, silicon carbide, and alumina.

Claim 20

Independent Claim 20 words

The method according Claims 1, 2 or 3 including a source of dopant used in conjunction with said parent metal.

Claim 21

Dependent Claim 34 words

The method of Claim 17 wherein said dopant source comprises a source of two or more of magnesium, zinc, silicon, germanium, tin, lead, boron, sodium, lithium, calcium, phosphorus, yttrium, and a rare earth metal.

Claim 22

Dependent Claim 40 words

The method of Claim 18 wherein said parent metal is an 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 source, and said oxidant.

Claim 23

Dependent Claim 37 words

The method of Claim 17 wherein said parent metal is aluminum and including at least one dopant source alloyed with said parent metal and at least one dopant source applied to the surface of said parent metal.

Claim 24

Independent Claim 42 words

The method according to Claims 1, 2 or 3 wherein said parent metal is aluminum used in conjunction with a source of dopant, said oxidant is air, said heating step is between 850°C and 1450°C, and said oxidation reaction product is alumina.

Method of making shaped ceramic composites with the use of a barrier

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