| 摘要 |
<p>A method for the manufacture of a unitary object comprising silicon nitride is described. A uniform powder mixture based on Si3N4 which contains SiO2 as a surface oxide coating, 4-12% by weight of Y2O3 and 0.50-2.5% of Al2O3 is prepared. The mixture is heated at 1000-1400 degree C at a pressure of at least 140.6 atmospheres (2000 psi) for a time of at least 1 minute, but sufficient for a nucleation reaction to take place in secondary phases. Heating is then increased to a temperature of 1680- 1750 degree C, under pressure, for a sufficient period of time to obtain 99.0% or more of full theoretical density in the pressed object.</p> |
