Mechanical properties of hot-pressed VB2-SiC composites with and without WC

In this study, VB2-20 vol% SiC composites with and without 5 vol% WC were prepared via hot-pressing at 1800 degrees C for dwell time of 1 h under 20 MPa in Ar. Relative densities of >96% were obtained for the two compositions composites. The mechanical properties of the resulting composites were evaluated at the temperatures ranging from room temperature to 1400 degrees C. The results show that the temperature dependence of the mechanical properties was strongly related to the addition of WC. For VB2-SiC composite without WC, a maximum strength of 585 +/- 55 MPa was obtained at 1000 degrees C, then the strength decreased to 236 +/- 11 MPa at 1400 degrees C, with substantially degradation of strength accompanying increase of temperature. For VB2-SiC-WC composite, on the other hand, the addition of WC enhanced high-temperature strength up to 1400 degrees C, with strengths in the range of 464-523 MPa. The strength was higher at elevated temperature than at room temperature; and a maximum strength of 523 +/- 27 MPa was obtained at 1200 degrees C. In addition, although at or below 1000 degrees C the strength was lower for VB2-SiC-WC than for VB2-SiC, above 1000 degrees C the strength was significantly higher for the former than for the latter.