The phase transformation behavior of Si3N4 with single Re2O3 (Re = Ce, Nd, Sm, Eu, Gd, Dy, Er, Yb) additive

摘要

In this work alpha-Si3N4 powder was heated at 1600-1800degreesC for 1.5 h with single rare earth oxide Re2O3 (Re = Ce, Nd, Sm, Eu, Gd, Dy, Er, Yb) additives, respectively. The transformation ratio of alpha-Si3N4 to beta-Si3N4 was determined by X-ray diffraction (XRD) and the behavior Of Si3N4 transformation was investigated. The results showed that the all of the Re2O3 additives could increase obviously the transformation ratio Of Si3N4 at 1600 degreesC or more when the amounts were 1 mol%, and the transformation ratio was nearly achieved to 100% at 1700 degreesC. While the anomalous change of transformation ratio was found when the amount of Re2O3 additive was 3 mol% and the heat temperature was 1600degreesC. In addition, it was found that the transformation ratio Of Si3N4 changed periodically with the atomic number of the lanthanide at 1650degreesC or less. (C) 2002 Elsevier Science B.V. All rights reserved. [References: 13]