Preparation of highly oriented β-SiC bulks by halide laser chemical vapor deposition

Highly oriented beta-SiC bulks with high hardness were fabricated by halide laser chemical vapor deposition (HLCVD) using SiCl4, CH4 and H-2 as precursors. The effects of total pressure (P-tot) and deposition temperature (T-dep) on the preferred orientation, microstructure, deposition rate (R-dep) and micro-hardness were investigated. The < 110 >-oriented beta-SiC bulks were obtained at low P-tot (2-4 kPa), non-oriented beta-SiC bulks were obtained at mediate P-tot (6 kPa), and < 111 >-oriented beta-SiC bulks were obtained at high P-tot (10-40 kPa), exhibiting faceted, cauliflower-like and six-fold pyramid-like microstructure, respectively. The maximum R-dep of < 111 >- and < 110 >-oriented beta-SiC bulks were 3600 and 1300 mu m/h at, respectively. The activation energy obtained by the plot of lgR(dep)-T-dep(-1) is 170 to 280 kJ mol(-1), showing an exponential relation with P-si. The Vickers micro-hardness of beta-SiC bulks increased with increasing P-tot and showed the highest value of 35 GPa at P-tot = 40 kPa with a complete < 111 > orientation. (C) 2016 Elsevier Ltd. All rights reserved.