Thermal shock behavior of 30 wt%BAS/Si3N4 self-reinforced composite

The thermal shock behavior of 30 wt%BAS/Si3N4 composite was evaluated by the water-quenching technique. The results show that the investigated composite possesses excellent thermal shock resistance. The critical temperature difference (Delta T-c) of the composite is over 1100 degrees C and the retained strength at a quenching-temperature difference of 1100 degrees C is hardly affected by the quenching cycles. It is attributed to its high strength and low Young's modulus. The in situ growth of elongated beta-Si3N4 grains are also beneficial to the improvement of thermal shock resistance due to the increased crack propagation resistance by crack deflection and grain pull-out mechanisms. In addition, the formation of an oxide layer on the sample surface before quenching may act as an additional thermal barrier and leads to a reduction in the intensity of thermal shock. (C) 2009 Elsevier B.V. All rights reserved.