Methods of making self-supporting ceramic structures

Claim 1

A method of producing a self-supporting ceramic structure comprising the steps of: (a) providing a first self-supporting ceramic body comprising (i) a first polycrystalline oxidation reaction product formed upon oxidation of a first molten parent metal with a first oxidant, and (ii) interconnected porosity at least partially accessible from one or more surfaces of said first ceramic body; (b) orienting a body of second parent metal and said first ceramic body relative to each other so that melting and oxidation reaction of said second parent metal with a vapor-phase oxidant will cause formation of a second polycrystalline oxidation reaction product in a direction towards and into said interconnected porosity of said first ceramic body; and (c) heating said second parent metal to a temperature region above its melting point but below the melting points of both the first and second oxidation reaction products to form a body of molten second parent metal and, within said temperature region, i) reacting said body of molten second parent metal with said vapor-phase oxidant to form said second polycrystalline oxidation reaction product; ii) maintaining at least a portion of said second oxidation reaction product in contact with and between said body of molten second parent metal and said vapor-phase oxidant, whereby said second parent metal is drawn through said second polycrystalline material towards the oxidant so that said second oxidation reaction product continues to form at the interface between the vapor-phase oxidant and previously formed second oxidation reaction product, and iii) continuing said reaction for a time sufficient to infiltrate at least a portion of said porosity of said first ceramic body with said second oxidation reaction product.

Claim 2

A method of producing a self-supporting ceramic structure comprising the steps of: (a) providing a first self-supporting ceramic body comprising (i) a first polycrystalline oxidation reaction product formed upon oxidation of a first molten parent metal with a first oxidant, and (ii) interconnected porosity at least partially accessible from one or more surfaces of said first ceramic body; (b) orienting a body of second parent metal and said first ceramic body relative to each other so that melting and oxidation reaction of said second parent metal with a vapor-phase oxidant will cause formation of a second polycrystalline oxidation reaction product in a direction towards and into said interconnected porosity of said first ceramic body; and (c) heating said second parent metal to a temperature region above its melting point but below the melting points of both the first and second oxidation reaction products to form a body of molten second parent metal and, within said temperature region, i) reacting said body of molten second parent metal with said vapor-phase oxidant to form said second polycrystalline oxidation reaction product; ii) maintaining at least a portion of said second oxidation reaction product in contact with and between said body of molten second parent metal and said vapor-phase oxidant, whereby said second parent metal is drawn through said second polycrystalline material towards the oxidant so that said second oxidation reaction product continues to form at the interface between the vapor-phase oxidant and previously formed second oxidation reaction product, and iii) continuing said reaction for a time sufficient to infiltrate at least a portion of said porosity of said first ceramic body with said second oxidation reaction product.

Claim 3

A method for producing a self-supporting ceramic structure, comprising a polycrystalline material obtained as an oxidation reaction product of at least one parent metal with an oxidant, comprising the steps of forming a first self-supporting ceramic body having porosity by: (a) heating a first parent metal to form a body of first molten parent metal and reacting said first molten parent metal with a first oxidant at a temperature which is sufficient to form a first oxidation reaction product, and maintaining said first oxidation reaction product in contact with, and extending between, said body of first molten parent metal and said first oxidant, (b) maintaining said temperature to progressively draw molten metal through said first oxidation reaction product towards said first oxidant so that the first oxidation reaction product continues to form at the interface between the first oxidant and previously formed first oxidation reaction product and (c) continuing said reaction for a time sufficient to produce a first self-supporting ceramic body comprising said first oxidation reaction product and at least some porosity said porosity being a result of at least one treatment step selected from the group consisting of (i) controlling the temperature at which the first oxidation reaction product is formed, (ii) controlling the length of time for formation of the first oxidation reaction product, (iii) varying composition of the first parent metal, (iv) combining dopant materials with the first parent metal, (v) subjecting the formed self-supporting body to a vaporizing atmosphere and (vi) subjecting the formed self-supporting body to a leachant; (d) orienting a body of second parent metal and said first self-supporting ceramic body relative to each other so that melting and oxidation reaction of said second parent metal with a vapor-phase oxidant will cause formation of a second polycrystalline oxidation reaction product of the second parent metal in a direction towards and into the porosity of said first self-supporting ceramic body; (e) heating said second parent metal to a temperature region above its melting point but below the melting points of both the first and second oxidation reaction products to form a body of molten second parent metal and, within said temperature region, (i) reacting said body of molten second parent metal with said vapor-phase oxidant to form said second polycrystalline oxidation reaction product; (ii) maintaining at least a portion of said second oxidation reaction product in contact with and between said body of molten second parent metal and said vapor-phase oxidant, whereby said second parent metal is drawn through said second polycrystalline material towards the oxidant so that said second oxidation reaction product continues to form at the interface between the vapor-phase oxidant and previously formed second oxidation reaction product, and (iii) continuing said reaction for a time sufficient to infiltrate at least a portion of said porosity of said first ceramic body with said second oxidation reaction product.

Claim 4

A method for producing a self-supporting ceramic structure, comprising a polycrystalline material obtained as an oxidation reaction product of at least one parent metal with an oxidant, comprising the steps of forming a first self-supporting ceramic body having porosity by: (a) heating a first parent metal to form a body of first molten parent metal and reacting said first molten parent metal with a first oxidant at a temperature which is sufficient to form a first oxidation reaction product, and maintaining said first oxidation reaction product in contact with, and extending between, said body of first molten parent metal and said first oxidant, (b) maintaining said temperature to progressively draw molten metal through said first oxidation reaction product towards said first oxidant so that the first oxidation reaction product continues to form at the interface between the first oxidant and previously formed first oxidation reaction product and (c) continuing said reaction for a time sufficient to produce a first self-supporting ceramic body comprising said first oxidation reaction product and at least some porosity said porosity being a result of at least one treatment step selected from the group consisting of (i) controlling the temperature at which the first oxidation reaction product is formed, (ii) controlling the length of time for formation of the first oxidation reaction product, (iii) varying composition of the first parent metal, (iv) combining dopant materials with the first parent metal, (v) subjecting the formed self-supporting body to a vaporizing atmosphere and (vi) subjecting the formed self-supporting body to a leachant; (d) orienting a body of second parent metal and said first self-supporting ceramic body relative to each other so that melting and oxidation reaction of said second parent metal with a vapor-phase oxidant will cause formation of a second polycrystalline oxidation reaction product of the second parent metal in a direction towards and into the porosity of said first self-supporting ceramic body; (e) heating said second parent metal to a temperature region above its melting point but below the melting points of both the first and second oxidation reaction products to form a body of molten second parent metal and, within said temperature region, (i) reacting said body of molten second parent metal with said vapor-phase oxidant to form said second polycrystalline oxidation reaction product; (ii) maintaining at least a portion of said second oxidation reaction product in contact with and between said body of molten second parent metal and said vapor-phase oxidant, whereby said second parent metal is drawn through said second polycrystalline material towards the oxidant so that said second oxidation reaction product continues to form at the interface between the vapor-phase oxidant and previously formed second oxidation reaction product, and (iii) continuing said reaction for a time sufficient to infiltrate at least a portion of said porosity of said first ceramic body with said second oxidation reaction product.