Mechanical Properties and Thermal-shock Resistance of Cobalt-coated Al_2O_3/TiC Composites

The mechanical properties of Al2O3/TiC composites with different cobalt content show that the best cobalt content is 8wt%.The thermal-shock resistance of Al2O3,Al2O3/TiC and cobalt-coated Al2O3/TiC composites were studied by residual-strength method.The single thermal-shock results show that thermal-shock resistance of cobalt-coated Al2O3/TiC composites is the best among the three materials at any thermal-shock temperature.From SEM observation it is found that the densities of composites became lower and lower with thermal-shock temperature increasing,which induce the mechanical properties decrease greatly,thereby led to the degrade of thermal-shock resistance.The cyclic thermal-shock results indicate that thermal-shock resistance became worse and worse with cyclic numbers increasing.The thermal physic parameters are changed very little but the mechanical properties of ATC composites are improved greatly by introducing few cobalt into AT composites,which contribute to the higher thermal shock resistance.