Oxidation of ZrB2-SiC Composites at 1600 °C: Effect of Carbides, Borides, Silicides, and Chopped Carbon Fiber

The aim of this work is to optimize the oxidation resistance of ZrB2-SiC-based composites with different additives. Effect of nine factors including SiC, Cf, MoSi2, HfB2 and ZrC contents, milling time of Cf (M.t) and SPS parameters such as temperature, time and pressure on oxidation resistance in four levels was investigated. Taguchi design was applied to explore effective parameters for achieving the highest oxidation resistance. Spark plasma sintering (SPS) was used for sintering. Oxidation resistance tests were carried out on all composites using box furnace at 1600 °C for 1 hr holding time. Then Taguchi design was applied to determine effect of each factor on it. It has been concluded that ZrC by 45% has the most significant the effect on the oxidation resistance and oxidation resistance decreases by ZrC ascent while HfB2 has positive effect on oxidation resistance of ZrB2-based ceramics. Among the SPS parameters, the temperature has the most effect on microstructure and eventually oxidation resistance. Pressure by 2.3% and M.t by 3.4% have the least effect on the oxidation resistance. Other factors such as SiC, Cf, temperature, HfB2, MoSi2 and time have 12.8%, 8.3%, 7.7%, 6.2%, 5.9% and 5.6% on the oxidation resistance respectively. 

Keywords:

Oxidation Resistance , Spark Plasma Sintering , ZrB2-SiC , carbides , borides and chopped carbon fiber