Effects of in situ synthesis of CNTs/SiCw on microstructure and properties of Al2O3-SiC-C composites

Al2O3-SiC-C composites were prepared using tabular corundum, ball pitch and silicon carbide as the main raw materials. The carbon nanotubes (CNTs) and SiC whiskers (SiCw) were in situ synthesized and their effects on the thermo-mechanical properties of Al2O3-SiC-C composites have been studied. The experimental results indicated that the high yield of SiCw and CNTs with large aspect ratio could be obtained due to addition of Ni(NO3)(2)center dot 6H(2)O as catalyst in the composites. The cold modulus of rupture values were increased by 24% to 7.2 MPa, and the flexural modulus was increased from 19 GPa to 24 GPa. Additionally, the hot modulus of rupture reached a maximum value of 3.6 MPa, which presented a 71% increase over that of composites without catalyst. After three thermal shock cycles, the residual cold crush strength was improved from 57.1% to 76.9%. It is believed that the enhancement in the thermo-mechanical properties of Al2O3-SiC-C composites could be attributed to the reinforcement effect of SiCw and CNTs.