SILICON NITRIDE - ALUMINUM OXIDE SOLID SOLUTION (SiAlON) FORMATION AND DENSIFICATION BY PRESSURE SINTERING

摘要

Stirred-ball-mill-blended Si3N4 and Al2O3 powders were pressure sintered in order to investi¬gate the mechanism of solid-solution formation and densification in the Si3N4-Al2O3 system. Powder blends with Si3N4:Al2O3 mole ratios of 4:1, 3:2, and 2:3 were pressure sintered at 27. 6-MN/m² (4000-psi) pressure at temperatures to 1700° C (3090° F). The compaction be¬havior of the powder blends during pressure sintering was determined by observing the density of the powder compact (ram travel) as a function of temperature and time starting from room temperature. This information, combined with the results of X-ray diffraction and metallographic analyses regarding solutioning and phase transformation phenomena in the Si3N4-Al2O3 system, was used to describe the densification behavior.