# US 5,702,766 A · Process of forming a ceramic article containing a core comprising zirconia and a shell comprising zirconium boride > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,702,766 A - Document ID: US5702766A - Status: Granted - Kind: A - Application number: 08/770,447 - Filed: 1996-12-20 - Granted: 1997-12-30 - Earliest claimed: 1996-12-20 - Assignees: Eastman Kodak Company - Inventors: Gregory S. Jarrold; Dilip K. Chatterjee; Syamal K. Ghosh - Web page: https://patentgrep.com/patent/US5702766A ## CPC - C04B 41/009: {characterised by the material treated} - C04B 35/488: Composites - C04B 41/507: {Borides} - C04B 41/87: Ceramics - H01B 1/14: Conductive material dispersed in non-conductive inorganic material - C04B 2111/00405: {Materials with a gradually increasing or decreasing concentration of ingredients or property from one layer to another} - C04B 2111/94: Electrically conducting materials - C04B: LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE {(roofing granules E04D7/005)}; CERAMICS (devitrified glass-ceramics C03C10/00); REFRACTORIES; TREATMENT OF NATURAL STONE - H01B: CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES (selection for magnetic properties H01F1/00; waveguides H01P {; printed circuits H05K}) ## Abstract A method for preparing a ceramic composite having a core/bulk of tetragonal zirconia alloy and a shell/surface comprising zirconium boride by sintering a zirconia or zirconia and alumina composite article in an argon atmosphere while in contact with boron carbide. ## Claims ### Claim 1 A method for preparing an electrically conductive ceramic article having a core/bulk of tetragonal zirconia alloy and a shell/surface comprising zirconium boride comprising: i. coating a zirconia or zirconia alloy green body with a boron carbide slurry; and ii. sintering in an argon atmosphere at between 1200.degree. C. to 1600.degree. C. ### Claim 2 (depends on 1) The method of claim 1 wherein the argon gas flow is from 1 to 3 liters per minute. ### Claim 3 (depends on 2) The method of claim 2 wherein the gas flow is 2 liters per minute. ### Claim 4 (depends on 1) The method of claim 1 wherein the core/bulk comprises from 99.9 to 50 weight percent zirconia alloy and from 0.1 to 50 weight percent zirconium boride. ### Claim 5 (depends on 1) The method of claim 1 wherein the zirconia alloy comprises a particulate zirconium oxide alloy having an elemental composition consisting essentially of Zr, O and at least one element selected from the group consisting of oxides of Mg, Ca, Y, Sc, Ce and rare earth elements, said particulate zirconium oxide alloy after sintering has a substantially tetragonal structure. ### Claim 6 (depends on 1) The method of claim 1 wherein the zirconia is doped with from 0.5 to 5 mole percent yttria. ### Claim 7 (depends on 1) The method of claim 1 wherein the zirconia is doped with 3 mole percent yttria. ### Claim 8 (depends on 5) The method of claim 5 wherein the electrically conductive ceramic composite comprises 95 to 50 weight percent zirconia alloy. ### Claim 9 (depends on 5) The method of claim 5 wherein the electrically conductive ceramic composite comprises 5 to 50 weight percent alumina. ### Claim 10 (depends on 1) The method of claim 1 wherein the sintering temperature is 1500.degree. C. ### Claim 11 (depends on 1) The method of claim 1 wherein the sintering time is from 1 to 3 hours. ### Claim 12 (depends on 11) The method of claim 11 wherein the sintering time is 2 hours. ### Claim 13 (depends on 1) The method of claim 1 wherein the sintering temperature is between 1200.degree. C. to 1600.degree. C. and the sintering time is 1 to 3 hours to yield a gradient material with varying zirconium boride concentrations from the end of the shell/surface to the core/bulk of the article. ### Claim 14 A method for preparing an electrically conductive ceramic article having a core/bulk of tetragonal zirconia alloy and a shell/surface comprising zirconium boride comprising: i. coating sintered tetragonal zirconia or a zirconia alloy article with boron carbide; and ii. reacting in an argon atmosphere at between 1200.degree. C. to 1600.degree. C. ### Claim 15 (depends on 14) The method of claim 14 wherein the argon gas flow is from 1 to 3 liters per minute. ### Claim 16 (depends on 15) The method of claim 15 wherein the gas flow is 2 liters per minute. ### Claim 17 (depends on 14) The method of claim 14 wherein the core/bulk comprises from 99.9 to 50 weight percent zirconia alloy and from 0.1 to 50 weight percent zirconium boride. ### Claim 18 (depends on 14) The method of claim 14 wherein the zirconia alloy comprises a particulate zirconium oxide alloy having an elemental composition consisting essentially of Zr, O and at least one element selected from the group consisting of oxides of Mg, Ca, Y, Sc, Ce and rare earth elements, said particulate zirconium oxide alloy after sintering has a substantially tetragonal structure. ### Claim 19 (depends on 14) The method of claim 14 wherein the zirconia is doped with from 0.5 to 5 mole percent yttria. ### Claim 20 (depends on 14) The method of claim 14 wherein the zirconia is doped with 3 mole percent yttria. ### Claim 21 (depends on 18) The method of claim 18 wherein the electrically conductive ceramic composite comprises 95 to 50 weight percent zirconia alloy. ### Claim 22 (depends on 18) The method of claim 18 wherein the electrically conductive ceramic composite comprises 5 to 50 weight percent alumina. ### Claim 23 (depends on 14) The method of claim 14 wherein the reaction temperature is 1500.degree. C. ### Claim 24 (depends on 14) The method of claim 14 wherein the reaction time is from 1 to 3 hours. ### Claim 25 (depends on 24) The method of claim 24 wherein the reaction time is 2 hours. ### Claim 26 (depends on 14) The method of claim 14 wherein the reaction temperature is between 1200.degree. C. and 1600.degree. C. and reaction time is 1 to 3 hours to yield a gradient material with varying zirconium boride concentrations from the end of the shell/surface to the core/bulk of the article.