Electrical heating element, related composites, and composition and method for producing such products using dieless micropyretic synthesis
OwnerJainagesh A. Sekhar, Naiping Zhuinventors
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Abstract
Electrical heating elements and related articles having oxidation resistance at high temperatures, produced by a method involving micropyretic synthesis. A composition subjected to micropyretic synthesis comprises a filler material, a reactive system capable of undergoing micropyretic synthesis, and (optionally) a plasticizer or extrusion agent. The method of preparation of articles includes slurry techniques, plastic extrusion, slip casting, or coating.
Claims4
A ceramic composite article having improved mechanical stability, room temperature fracture toughness, oxidation resistance at temperatures up to 1900.degree. C., and stable electrical conductivity at said temperatures, comprising a ceramic composite formed by micropyretic synthesis of a non-solid, pliable composition comprising, based on the total weight of said composition:
- a filler material selected from the group consisting of up to about 4% chromium, up to about 17% ixon, up to about 2% aluminum, about 38-42% silicon carbide, about 6-12% Y.sub.2 O.sub.3, about 1-3% Al.sub.2 O.sub.3, about 5-7% SiO.sub.2, up to about 2.5% MgO and mixtures thereof;
- a reactive system consisting essentially of from about 20% to about 35% nickel and about 3% to about 6% aluminum, which materials will react exothermically with one another and are present in such proportion to one another that combustion will occur when ignited;
- and
- as a plasticizer about 8% to about 12% of a 2.5% aqueous chemical cellulose solution.
A ceramic composite article having improved mechanical stability, room temperature fracture toughness, oxidation resistance at temperatures up to 1900.degree. C., and stable electrical conductivity at said temperatures, comprising a ceramic composite formed by micropyretic synthesis of a non-solid, pliable composition comprising, based on the total weight of said composition:
- a filler material selected from the group consisting of from about 8% to about 10% SiO.sub.2, up to about 75% MoSi.sub.2 up to about 2% silicon, about 0.8% to about 40% silicon carbide, up to about 0.5% boron, up to about 8% Y.sub.2 O.sub.3, and up to about 2% Si.sub.3 N.sub.4 ;
- a reactive system consisting essentially of from about 7% to about 28% Cr.sub.2 O.sub.3, about 2.5% to about 10% aluminum, and about 0.7% to about 3% carbon, which materials will react exothermically with one another and are present in such proportion to one another that combustion will occur when ignited;
- and
- a plasticizer selected from the group consisting of from about 4% to about 5% polyvinyl butyral, about 8% to about 12% of a 2.5% aqueous chemical cellulose solution and mixtures thereof.
A ceramic composite article having improved mechanical stability, room temperature fracture toughness, oxidation resistance at temperatures up to 1900.degree. C., and stable electrical conductivity at said temperatures, comprising a ceramic composite formed by micropyretic synthesis of a non-solid, pliable composition comprising, based on the total weight of said composition:
- a filler material selected from the group consisting of from about 1% to about 50% silicon carbide, up to about 71% MoSi.sub.2, up to about 10% SiO.sub.2, up to about 10% Y.sub.2 O.sub.3, up to about 10% Si.sub.3 N.sub.4, up to about 0.5% BN, up to about 1% chromium, up to about 1% boron, up to about 0.5% aluminum, up to about 10% Al.sub.2 O.sub.3, up to about 0.5% silicon, about up to about 7% ZrO.sub.2 ;
- a reactive system consisting essentially of from about 7% to about 30% MoO.sub.3, about 2.5% to about 11% aluminum, about 2.5% to about 38% silicon;
- and up to about 11% carbon, which materials will react exothermically with one another and are present in such proportion to one another that combustion will occur when ignited;
- and
- a plasticizer selected from the group consisting of from about 10% to about 15% polyvinyl butyral, about 8% to about 15% of a 2.5% aqueous chemical cellulose solution, about 8% to about 10% of a mixture of fused silica, about 4 % to about 10% bentonite and mixtures thereof.
A ceramic composite article having improved mechanical stability, room temperature fracture toughness, oxidation resistance at temperatures up to 1900.degree. C., and stable electrical conductivity at said temperatures, comprising a ceramic composite formed by micropyretic synthesis of a non-solid, pliable composition comprising, based on the total weight of said composition:
- a filler material selected from the group consisting of from about 35% to about 40% silicon carbide, about 7% to about 8% Y.sub.2 O.sub.3, about 1.7% to about 2% Al.sub.2 O.sub.3, about 7% to about 8% SiO.sub.2, and about 1.7% to about 2% MgO;
- a reactive system consisting essentially of from about 25% to about 30% titanium, and about 9% to about 11% silicon, which materials will react exothermically with one another and are present in such proportion to one another that combustion will occur when ignited;
- and
- as a plasticizer, from about 8% to about 12% of a 2.5% aqueous chemical cellulose solution.
Dependencies are inferred from the claim text.