Oxidation resistance of SiC nanowires reinforced SiC coating prepared by a CVD process on SiC-coated C/C composites

Oxidation protective SiC nanowires-reinforced SiC (SiCNWs-SiC) coating was prepared on pack cementation (PC) SiC-coated carbon/carbon (C/C) composites by a simple chemical vapor deposition (CVD) process. This double-layer SiCNWs-SiC/PC SiC-coating system on C/C composites not only has the advantages of SiC buffer layer but also has the toughening effects of SiCNWs. The microstructure and phase composition of the nanowires and the coatings were examined by SEM, TEM, and XRD. The single-crystalline -SiC nanowires with twins and stacking faults were deposited uniformly and oriented randomly with diameter of 50-200nm and length ranging from several to tens micrometers. The dense SiCNWs-SiC coating with some closed pores was obtained by SiC nanocrystals stacked tightly with each other on the surface of SiCNWs. After introducing SiCNWs in the coating system, the oxidation resistance is effectively improved. The oxidation test results showed that the weight loss of the SiCNWs-SiC/PC SiC-coated samples was 4.91% and 1.61% after oxidation at 1073K for 8hours and at 1473K for 276hours, respectively. No matter oxidation at which temperature, the SiCNWs-SiC/PC SiC-coating system has better anti-oxidation property than the single-layer PC SiC coating or the double-layer CVD SiC/PC SiC coating without SiCNWs.