Description:
<jats:p>Pressureless sintering of silicon carbide powder requires addition of sintering aids and high sintering temperature (>2100°C) in order to achieve high sintered density (>95% T.D.). The high sintering temperature normally causes an exaggerated grain growth which can compromise the mechanical properties. Two-step sintering (TSS) can be used to overcome this problem. By this method, high sintered density is obtained avoiding the grain growth associated to the last step of the sintering. Two-step sintering was successfully applied to different commercial silicon carbide powders with different sintering mechanism: solid-state and liquid-phase sintering. In both cases the sintering temperature was set nearly 100 °C below the temperature conventionally required. Microstructures of samples obtained by TSS and conventional sintering (CS) processes were compared. TSS-SiC showed finer microstructure consisted of equiaxed grains with very similar density. The beneficial effects of the two-step sintering process were more evident in the solid state sintering. In this case sintered density higher than 98% was achieved with T<2000 °C.</jats:p>