Synthesis and Properties of Porous Single‐Phase β′‐SiAlON Ceramics

Single‐phase β′‐SiAlON (Si 6− z Al z O z N 8− z , z = 0–4.2) ceramics with porous structure have been prepared by pressureless sintering of powder mixtures of á‐Si 3 N 4 , AlN, and Al 2 O 3 of the SiAlON compositions. A solution of AlN and Al 2 O 3 into Si 3 N 4 resulted in the β′‐SiAlON, and full densification was prohibited because no other sintering additives were used. Relative densities ranging from 50%–90% were adjusted with the z ‐value and sintering temperature. The results of X‐ray diffraction, scanning electron microscopy, and transmission electron microscopy analyses indicated that single‐phase β′‐SiAlON free from a grain boundary glassy phase could be obtained. Both grain and pore sizes increased with increasing z ‐value. Low z ‐value resulted in a relatively high flexural strength.