ZrB 2 ‐SiC w ceramic composites synthesized by in situ reaction and spark plasma sintering

Abstract SiC whisker reinforced ZrB 2 ‐SiC w composites were prepared by sol‐gel method and spark plasma sintering ( SPS ) with designed composition of 10‐30 vol% SiC w . The ZrB 2 ‐SiC w composite powder was synthesized by sol‐gel method using zirconium diboride, tetraethoxysilane ( TEOS ), and activated carbon as starting materials, then densified by SPS at 1700°C under a pressure of 40 MPa for 5 minutes. The phase compositions and microstructures of ZrB 2 ‐SiC w composites were investigated by X‐ray diffraction and scanning electron microscope, respectively. The relative density of ZrB 2 ‐SiC w composites increased from 83% to 98.5% with increasing SiC w contents from 10 vol% to 30vol% after sintering at 1700°C without additional sintering additives. Meanwhile, the fracture toughness and flexural strength of as‐obtained composites exhibited a similar trend as relative density. ZrB 2 ‐30vol% SiC w composite showed the highest fracture toughness of 6.1 MPa·m 1/2 and flexural strength of 350 MP a, which were attributed to the formation of SiC whisker.