Preparation and oxidation characteristics of ZrC-ZrB2 composite powders with different proportions

Abstract

ZrC and ZrB2 are both typical ultra-high temperature ceramics, which can be used in the hyperthermal environment. In this study, a method for preparing ultrafine ZrC-ZrB2 composite powder was provided, by using the raw materials of nano ZrO2, carbon black, B4C, and metallic Ca. It is worth pointing out that ZrC-ZrB2 composite powder with any proportion of ZrC to ZrB2 could be synthesized by this method. Firstly, a mixture of ZrC and C was prepared by carbothermal reduction of ZrO2. By adjusting the addition amount of B4C, ZrC was boronized by B4C to generate ZrC-ZrB2 composite powder with different compositions. Using this method, five composite powders with different molar ratios of ZrC and ZrB2 (100ZrC, 75ZrC-25ZrB2, 50ZrC-50ZrB2, 25ZrC-75ZrB2, and 100ZrB2) were prepared. When the temperature of boronization and decarburization process was 1473 K, the particle size of product was only tens of nanometres. Finally, the oxidation characteristics of different composite powders were investigated through oxidation experiments. The oxidation resistance of ZrC-ZrB2 composite powder continued to increase as the content of ZrB2 increased.