Formation of oxide films on ZrB 2-15 vol% SiC composites during oxidation: Evolution with time and temperature

Abstract

The evolution of convection cells features that form in oxide films on ZrB 2-SiC composites are quantified by the number population, size, and distribution in oxide films on ZrB 2-15 vol% SiC oxidized at temperatures between 1500° and 1600°C for various oxidation times. The number of convection cells per unit area increases after short exposure times of the oxidation at 1550°C, but then decreases slowly with increasing time. The results indicate that these convection cells are transient, they form and transport boria-silica-zirconia liquid to the surface but with increasing exposure time the increasing amount of flowing viscous SiO 2-rich liquid submerges them and they become extinct. © 2009 The American Ceramic Society.