초록 ▼

A method of making a unitary silicon nitride comprising object is disclosed. A uniform powder mixture is prepared of Si3N4 containing SiO2 as an oxide surface coating, 4-12% by weight Y2O3, and 0.50-2.5% Al2O3. The mixture is heated to 1000°-1400°C. under a pressure of at least 2,000 psi for a time

A method of making a unitary silicon nitride comprising object is disclosed. A uniform powder mixture is prepared of Si3N4 containing SiO2 as an oxide surface coating, 4-12% by weight Y2O3, and 0.50-2.5% Al2O3. The mixture is heated to 1000°-1400°C. under a pressure of at least 2,000 psi for a time of at least one minute but sufficient to permit a nucleating reaction to take place in secondary phases. Heating is then increased to a temperature of 1680°-1750°C. under a pressure and for a period of time sufficient to produce 99.0% or more of full theoretical density in the pressed object.

대표청구항 ▼

A method of making a unitary silicon nitride comprising object by the steps comprising: (a) uniformly mixing silicon nitride powder containing SiO2 as an oxide surface coating, 4-12% by weight Y2O3 powder, and 0.05-2.5% Al2O3; (b) heating the mixture to 1000°-1400°C. under a pressure of at least 200

A method of making a unitary silicon nitride comprising object by the steps comprising: (a) uniformly mixing silicon nitride powder containing SiO2 as an oxide surface coating, 4-12% by weight Y2O3 powder, and 0.05-2.5% Al2O3; (b) heating the mixture to 1000°-1400°C. under a pressure of at least 2000 psi and for a time of at least one minute but sufficient to permit a nucleating reaction to take place in secondary phases formed as a result of heating; and (c) continuing to heat the mixture to a temperature of 1680°-1750°C. under a pressure and for a period of time sufficient to produce 99% or more of full theoretical density in said pressed mixture.