Toughened ZrB2-based ceramics through SiC whisker or SiC chopped fiber additions

In order to improve the fracture toughness. SiC whiskers or SiC chopped fibers were added to a ZrB2 matrix in volumetric fraction of 10 and 20 vol.%. The composites were hot-pressed between 1650 and 1730 degrees C and their final relative densities were higher than 95% Even at the lowest sintering temperature, the: whiskers showed an evident degradation. On the other hand, the fibers maintained their initial shape and a strong interface formed between matrix and reinforcement. The fracture toughness of the composites Increased from 30 to 50% compared to the baseline material, with the fibers showing a slightly higher toughening effect In the whiskers-reinforced composites, the room-temperature strength increased when 10 vol % whiskers were added In the fibers-reinforced composites, the room-temperature strength decreased regardless the amount of fibers added. The high-temperature strength of the composites was higher than that of the baseline material for both types of reinforcement. (C) 2009 Elsevier Ltd All rights reserved