A route for the pressureless liquid-phase sintering of SiC with low additive content for improved sliding-wear resistance

A colloidal processing route has been developed for the pressureless sintering of dense SiC with a low content of sintering additives. In this route, a sol-gel solution precursor of the sintering additives is deposited onto the surface of the SiC particles, achieving a uniform distribution of the sintering additives in the green compact. This in turn promotes complete densification at short sintering times, which is not otherwise achievable when the batch is prepared by the standard method of mechanically mixing powders. It is also shown that the resulting ceramic has improved sliding-wear resistance compared to its counterpart prepared by the classical method, with essentially the same rate of mild and severe wear but a notably delayed transition from the mild to the severe wear regimes. This improvement is attributed to the reduction in the microstructural defect size achieved by the colloidal processing. Implications for the fabrication of low-cost SiC ceramics for wear-resistance applications are discussed. (C) 2011 Elsevier Ltd. All rights reserved.