Oxidation Behavior of Multi-Canon a-Sialons Containing Rare Earth

The oxidation behavior of multi-canon Sialons containing Nd and Y or Yb for the compositions (Nd0.18Y0.18)Si10.38Al1.62O0.54N15.46and (Nd0.18 yb0.18)Si10.38Al1.62O0.54 was inves-tigated in the temperatrue range of 1200 to 1400 in air ,The samples sere prepared by hot-pressin technique .The results indicated that there existed silicate grains containing noedymium and yttrium or ytterbium in preferred orientation on the surface of multi-cation (Nd,Y)-and (Nd Yb) Sialon respectively oxidized at 1200 or 1300 for 20h,By increase of oxidation temperature ,bubble,which was caused by softening of silicate oxidation layer,occurred and galssyphase appeared obviously on the surfaces of xididized samles.The phases formed on the surfacesof multi -cation Sialons during the oxidation were also discussed in this paper.