Fractography, Mechanical Properties, and Microstructure of Commercial Silicon Nitride–Titanium Nitride Composites

Abstract

Commercial‐grade Si 3 N 4 –TiN composites with 0, 10, 20, and 30 wt% TiN content have been characterized. Submicrometer grain‐size Si 3 N 4 was reinforced with fine TiN grains. Density, Young's modulus, coefficient of thermal expansion, and fracture toughness increased linearly with TiN content. Increased strength was observed in the Si 3 N 4 +20 wt% TiN, and Si 3 N 4 +30 wt% TiN composites. Fractography was used to characterize the different types of fracture origins. Improvements in toughness and strength are due to residual stresses in the Si 3 N 4 matrix and the TiN particles. A threefold improvement in dry wear resistance of the Si 3 N 4 +30 wt% TiN composite over the Si 3 N 4 matrix was observed.