SiC-ZrO2(3Y)-Al2O3 nanocomposites superfast densified by spark plasma sintering

Heterogeneous precipitation method has been used to produce 5 wt% SiC-15 wt% ZrO2-Al2O3 powder, from aqueous suspension of nano-SiC, aqueous solutions of zirconium oxychloride, yttrium nitrate and aluminium chloride and ammonia. The resulting gel was calcined at 1100 degrees C. Nano-SiC-ZrO2(3Y)-Al2O3 composites were superfast densified using spark plasma sintering (SPS) process by heating to a sintering temperature in the range of 1350 to 1600 degrees C, at a heating rate of 600 degrees C/min, with no holding time, and then fast cooled to 600 degrees C within 2-3 minutes. High density composites could be achieved at lower sintering temperatures by SPS, as compared with that by hot-press sintering process. Bending strength of 5 wt% SiC-15 wt% ZrO2(3Y)-Al2O3 superfast densified by SPS at 1450 degrees C reached as high as 1.2 GPa. Microstructure studies found that the nano-SiC particles were mainly located within the Al2O3 grains and the fracture mode of the nanocomposites was transgranular fracture. (C) 1999 Acta Metallurgica Inc.