Microstructure, mechanical properties and thermal shock resistance of nano-TiN modified TiC-based cermets with different binders

Microstructure, mechanical properties and thermal shock resistance of TiC-based cermets modified by nano-TiN were studied. The highest transverse rupture strength, fracture toughness and hardness were obtained for the cermets with the compositions 14Mo-20Ni (cermet A), 4Mo-10Co-10Ni (cermet B) and 4Mo-20Co (cermet C), respectively. The quenching-strength method and indentation-quench method were used for studying the thermal shock resistance of nano-TiN modified TiC-based cermets. The results of quenching-strength test denote that the critical temperature differences for sharp decline of residual strength are about 410, 370 and 330 degrees C for cermets A. B and C, respectively. The results of indentation-quench test show that the micro crack length increases and the micro cracks propagate fast with increasing thermal shock temperature and cycles. The propagation rate of the crack is controlled by the stress intensity of crack tip. Both tests show that cermets with high transverse rupture strength have excellent thermal shock resistance. Thermal shock resistance parameter R and R-st calculated are in good agreement with the experimental results. (C) 2008 Published by Elsevier Ltd.