Method of making ceramic composite articles with shape replicated surfaces and articles obtained thereby

Claim 1

A method for producing self-supporting ceramic com­posite body having a negative pattern inversely replicating a positive pattern of a parent metal precursor, said composite body 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 an oxidant and, optionally, (ii) one or more metallic constituents; and (2) a filler embedded by said matrix, the method comprising the steps of: (a) providing a parent metal precursor having (1) a positive pattern section for inverse replication, and (2) a non-replicating section; (b) emplacing at least said positive pattern section of said parent metal precursor in conforming engagement with a bed of conformable filler under growth control conditions to promote growth of said oxidation reaction product from said positive pattern section and to inhibit such growth from said non-replicating section, said conformable filler (i) being permeable to said oxidant at least when required for said oxidant to contact the molten parent metal in step (c), and (ii) being permeable to infiltration by the growth of the oxidation reaction product through said filler; (c) heating the parent metal precursor to a temper­ature region above its melting point but below the melting point of said oxidation reaction product to form a body of molten parent metal and, at said temperature, (1) reacting the molten parent metal with said oxidant to form said oxidation reaction product, (2) maintaining at least a portion of said oxidation reaction product in contact with and between said body of molten metal and said oxidant, to pregressively draw molten metal from said body of molten metal through the oxidation reaction product and into contact with said oxidant within said bed of filler to concurrently form said negative pattern in said bed of filler as oxidation reaction product continues to form at the interface between said oxidant and previously formed oxidation reaction product, and (3) continuing said reacting for a time to at least partially embed said bed of filler within said oxidation reaction product by growth of the latter to form said composite body with said negative pattern; and (d) separating the resulting self-supporting ceramic composite body from excess filler and unreacted parent metal, if any.

Claim 2

A method for producing self-supporting ceramic com­posite body having a negative pattern inversely replicating a positive pattern of a parent metal precursor, said composite body 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 an oxidant and, optionally, (ii) one or more metallic constituents; and (2) a filler embedded by said matrix, the method comprising the steps of: (a) providing a parent metal precursor having (1) a positive pattern section for inverse replication, and (2) a non-replicating section; (b) emplacing at least said positive pattern section of said parent metal precursor in conforming engagement with a bed of conformable filler under growth control conditions to promote growth of said oxidation reaction product from said positive pattern section and to inhibit such growth from said non-replicating section, said conformable filler (i) being permeable to said oxidant at least when required for said oxidant to contact the molten parent metal in step (c), and (ii) being permeable to infiltration by the growth of the oxidation reaction product through said filler; (c) heating the parent metal precursor to a temper­ature region above its melting point but below the melting point of said oxidation reaction product to form a body of molten parent metal and, at said temperature, (1) reacting the molten parent metal with said oxidant to form said oxidation reaction product, (2) maintaining at least a portion of said oxidation reaction product in contact with and between said body of molten metal and said oxidant, to pregressively draw molten metal from said body of molten metal through the oxidation reaction product and into contact with said oxidant within said bed of filler to concurrently form said negative pattern in said bed of filler as oxidation reaction product continues to form at the interface between said oxidant and previously formed oxidation reaction product, and (3) continuing said reacting for a time to at least partially embed said bed of filler within said oxidation reaction product by growth of the latter to form said composite body with said negative pattern; and (d) separating the resulting self-supporting ceramic composite body from excess filler and unreacted parent metal, if any.

Claim 4

The method of Claims 1 or 2 which includes providing means overlaying at least a portion of said non-replicating section of said parent metal for inhibiting growth of said oxidation reaction product from said non-replicating section.

Claim 11

The method of any one of any of the preceding claims wherein said oxidant comprises a vapor-phase oxidant.

Claim 13

The method of any one of the preceding claims wherein said parent metal is selected from the group consisting of aluminum, silicon, titanium, tin, zirconium and hafnium parent metals.

Claim 14

A method for producing a self-supporting ceramic composite body having a negative pattern inversely replicating a positive pattern of a parent metal precursor, said composite body comprising (1) a ceramic matrix obtained by oxidation of an aluminum parent metal to form a polycrystalline material consisting essentially of (i) the alumina oxidation reaction product of said parent metal with air and, optionally, (ii) one or more metallic constituents; and (2) a filler embedded by said matrix, the method of comprising the steps of: (a) providing an aluminum parent metal precursor having (1) a positive pattern section for inverse replication, and (2) a non-replicating section; (b) emplacing at least said positive pattern section of said parent metal precursor in conforming engagement with a bed of conformable filler under growth control conditions to promote growth of said oxidation reaction product primarily or exclusively from said positive pattern section and to inhibit such growth from said non-replicating section, said conformable filler (i) being permeable to air to enable contact of the molten parent metal by air in step (c), and (ii) being permeable to infiltration by the growth of the oxidation reaction product through said filler; (c) heating the emplaced positive pattern to a temperature region of from about 850°C to about 1450°C to form a body of molten aluminum parent metal and, at said temperature, (1) reacting the molten parent metal with said air to form said alumina oxidation reaction product (2) maintaining at least a portion of said alumina oxidation reaction product in contact with and between said body of molten metal and said air, to progressively draw molten metal from said body of molten metal through the alumina oxidation reaction product and into said bed of filler to concurrently form said negative pattern in said bed of filler as alumina oxidation reaction product continues to form at the interface between said air and previously formed alumina oxidation reaction product, and (3) continuing said reacting for a time to at least partially embed said bed of filler within said alumina oxidation reaction product by growth of the latter to form said composite body with said negative pattern; and (d) separating the resulting self-supporting ceramic composite body from excess filler and unreacted parent metal, if any.

Claim 15

A method for producing a self-supporting ceramic composite body having a negative pattern inversely replicating a positive pattern of a parent metal precursor, said composite body comprising (1) a ceramic matrix obtained by oxidation of an aluminum parent metal to form a polycrystalline material consisting essentially of (i) the alumina oxidation reaction product of said parent metal with air and, optionally, (ii) one or more metallic constituents; and (2) a filler embedded by said matrix, the method of comprising the steps of: (a) providing an aluminum parent metal precursor having (1) a positive pattern section for inverse replication, and (2) a non-replicating section; (b) emplacing at least said positive pattern section of said parent metal precursor in conforming engagement with a bed of conformable filler under growth control conditions to promote growth of said oxidation reaction product primarily or exclusively from said positive pattern section and to inhibit such growth from said non-replicating section, said conformable filler (i) being permeable to air to enable contact of the molten parent metal by air in step (c), and (ii) being permeable to infiltration by the growth of the oxidation reaction product through said filler; (c) heating the emplaced positive pattern to a temperature region of from about 850°C to about 1450°C to form a body of molten aluminum parent metal and, at said temperature, (1) reacting the molten parent metal with said air to form said alumina oxidation reaction product (2) maintaining at least a portion of said alumina oxidation reaction product in contact with and between said body of molten metal and said air, to progressively draw molten metal from said body of molten metal through the alumina oxidation reaction product and into said bed of filler to concurrently form said negative pattern in said bed of filler as alumina oxidation reaction product continues to form at the interface between said air and previously formed alumina oxidation reaction product, and (3) continuing said reacting for a time to at least partially embed said bed of filler within said alumina oxidation reaction product by growth of the latter to form said composite body with said negative pattern; and (d) separating the resulting self-supporting ceramic composite body from excess filler and unreacted parent metal, if any.