Shaped ceramic composites and methods of making the same

Claim 1

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 material consisting essentially of (i) the oxidation reaction product of said parent metal with one or more oxidants including a vapor-phase oxidant, and, optionally, (ii) one or more metallic constituents, said method comprising the steps of: 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; contacting a zone of a permeable preform with said body of molten metal, said permeable preform having at least one defined surface boundary spaced from said contacting zone such that formation of said oxidation reaction product will occur into said preform and in a direction toward said defined surface boundary; and at said temperature (a) reacting said molten metal with said oxidant to form said oxidation reaction product, (b) maintaining at least a portion of said oxidation reaction product in contact with and between said molten metal and said oxidant, to progressively draw molten metal through the oxidation reaction product towards 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 the preform, and (c) continuing said reacting until said polycrystalline material has infiltrated said preform to said defined surface boundary to produce said ceramic composite body having a configuration of said preform.

Claim 2

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 material consisting essentially of (i) the oxidation reaction product of said parent metal with one or more oxidants including a vapor-phase oxidant, and, optionally, (ii) one or more metallic constituents, said method comprising the steps of: 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; contacting a zone of a permeable preform with said body of molten metal, said permeable preform having at least one defined surface boundary spaced from said contacting zone such that formation of said oxidation reaction product will occur into said preform and in a direction toward said defined surface boundary; and at said temperature (a) reacting said molten metal with said oxidant to form said oxidation reaction product, (b) maintaining at least a portion of said oxidation reaction product in contact with and between said molten metal and said oxidant, to progressively draw molten metal through the oxidation reaction product towards 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 the preform, and (c) continuing said reacting until said polycrystalline material has infiltrated said preform to said defined surface boundary to produce said ceramic composite body having a configuration of said preform.

Claim 3

A method for producing a ceramic composite body of desired shape comprising a preform infiltrated by a ceramic matrix obtained by oxidation of an aluminum parent metal to form a polycrystalline material consisting essentially of (i) alumina as an oxidation reaction product of said aluminum parent metal with an oxygen-containing gas as oxidant, and, optionally, (ii) one or more metallic constituents, said method comprising the steps of: (a) providing a preform with at least one defined surface boundary, said preform being permeable to said oxidant and to infiltration by the growth of the oxidation reaction product; (b) applying a suitable dopant into said aluminum parent metal, or onto said aluminum parent metal, or incorporated within said preform, or any combination thereof; (c) heating said aluminum parent metal to a temperature between about 850°C and 1450°C to form a body of molten metal, and contacting said permeable preform with said body of molten metal at a zone spaced from said defined surface boundary such that formation of said oxidation reaction product will occur into said preform and in a direction towards said defined surface boundary; and at said temperature; (i) reacting said molten metal with said oxidant to form alumina as 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 draw molten metal through the oxidation reaction product towards 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 the preform; and (iii) continuing said reacting until said polycrystalline material has infiltrated said preform to the defined surface boundary of the latter to produce said ceramic composite body having a configuration of said preform.

Claim 4

A method for producing a ceramic composite body of desired shape comprising a preform infiltrated by a ceramic matrix obtained by oxidation of an aluminum parent metal to form a polycrystalline material consisting essentially of (i) alumina as an oxidation reaction product of said aluminum parent metal with an oxygen-containing gas as oxidant, and, optionally, (ii) one or more metallic constituents, said method comprising the steps of: (a) providing a preform with at least one defined surface boundary, said preform being permeable to said oxidant and to infiltration by the growth of the oxidation reaction product; (b) applying a suitable dopant into said aluminum parent metal, or onto said aluminum parent metal, or incorporated within said preform, or any combination thereof; (c) heating said aluminum parent metal to a temperature between about 850°C and 1450°C to form a body of molten metal, and contacting said permeable preform with said body of molten metal at a zone spaced from said defined surface boundary such that formation of said oxidation reaction product will occur into said preform and in a direction towards said defined surface boundary; and at said temperature; (i) reacting said molten metal with said oxidant to form alumina as 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 draw molten metal through the oxidation reaction product towards 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 the preform; and (iii) continuing said reacting until said polycrystalline material has infiltrated said preform to the defined surface boundary of the latter to produce said ceramic composite body having a configuration of said preform.

Claim 5

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

Claim 6

The method of any of Claims 1, 2 or 3 additionally including at least one of a solid oxidant or a liquid oxidant incorporated into at least a portion of said preform, additionally reacting said molten metal with said additional oxidants, and said polycrystalline material further including the oxidation reaction products of said parent metal with said additional oxidants.

Claim 8

The method of any of Claims 1, 3, 4 or 5 wherein said vapor-phase oxidant as elements, as vaporizable or volatile elements or as compounds or constituents of compounds, or as mixtures is selected from the group consisting of an oxygen-containing gas, a nitrogen-containing gas, a halogen, sulfur, phosphorus, arsenic, carbon, boron, selenium, tellurium, methane, ethane, propane, acetylene, ethylene, propylene, air, H 2 /H 2 0, and GOIC0 2 -

Claim 9

The method of Claims 1, 3, 4, 5 or 6 wherein said oxidant is an oxygen-containing or a nitrogen-containing gas and said temperature is from about 850°C to about 1450°C.

Claim 10

The method according to any of the foregoing Claims, including the step of establishing within the preform oxidation kinetics of the parent metal more favorable than outside the preform thereby preferentially causing development of said matrix within said preform and minimizing overgrowth of said matrix beyond the boundaries of said preform.

Claim 11

The method according to any of the foregoing Claims including using at least one suitable dopant material in conjunction with said parent metal.