PREPARATION OF MIXED FINE Al//2O//3-HfO//2 POWDERS BY HYDROTHERMAL OXIDATION.

Abstract

Mixed Al//2O//3-HfO//2 powders were prepared by hydrothermal oxidation of the intermetallic compound HfAl//3 and the mixture HfAl//3-4Al at 400 degree to 700 degree C under 100 MPa. Monoclinic HfO//2 with particle sizes of 10-20 nm was finely dispersed among the alpha -Al//2O//3 with sizes ranging from nanometers to micrometers. The temperature-time dependence of the reactions of Al, HfAl//3, and HfAl//3-4Al with H//2O was examined.