Relations between composition and microstructure of sialons

The relation between compn. and microstructure of Sialon ceramics was studied. Fully dense yttrium-contg. a'- and a'+b'-Sialon ceramics were prepd. by gas pressure sintering. Addnl., the effect of La2O3 as a sintering additive was investigated. Exptl. results reveal that the typical microstructure of these Sialon ceramics consists of a cryst. phase of Sialons and a small fraction of amorphous phase remaining at grain boundaries. The compn. of the amorphous phase is very similar, both in a'- and b'-Sialon ceramics. However, the amt. of the amorphous phase increases with increasing amt. of oxides used in the starting mixts. The a'- and a'+b'-Sialons exhibit differences in grain size and grain morphol. The addn. of La2O3 to the starting mixts. promotes the incorporation of yttrium ions into the crystal lattice and leads to the formation of crystal defects in the a'-grains. [on SciFinder (R)]