Microscopic, mechanical and thermal properties of spark plasma sintered ZrB2 based composite containing polycarbosilane derived SiC

ZrB2-SiCp (w/w 80:20) composites were spark plasma sintered at 1900, 2000 and 2100 degrees C with t(on) = 50 ms and t(off) = 5 ms conditions under 50 MPa pressure for 15 min. SiC was obtained by in situ pyrolysis of polycarbosilane during sintering. The FTIR spectra of semi-pyrolysed ZrB2-SiCp powder showed that pre-ceramic PCS polymeric bands such as Si-CH2-Si, Si-CH3 and Si-H weakened and few characteristic bands like Si-C, Si-O and C = C peaks appeared strong in the spectra. In ZrB2-SiCP composition, uniform distribution of ZrB2 and secondary SiC phases were found in the sintered sample. The interfaces between hexagonal ZrB2 and needle shaped SiC were found in high resolution bright field TEM images. The Vickers' micro-hardness, fracture toughness (measured by DCM) of ZrB2-SiCp composite sintered at 2000 degrees C achieved up to 16.22 GPa and 3.69 MPa root m, respectively. The critical energy release rate (G(IC)) value was 27.46 J.m(-2) implying that the composite resists fracture during indentation. Wear resistance coefficient and wear rate values of all the composites were found to be very low. Thermal conductivity values of all the composites varied from 78.09 to 57.20 W/m.K in 100 degrees C to 1000 degrees C range. (C) 2015 Elsevier Ltd. All rights reserved.