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

Highly oriented β-SiC bulks with high hardness were fabricated by halide laser chemical vapor deposition (HLCVD) using SiCl4, CH4 and H2 as precursors. The effects of total pressure (Ptot) and deposition temperature (Tdep) on the preferred orientation, microstructure, deposition rate (Rdep) and micro-hardness were investigated. The 〈110〉-oriented β-SiC bulks were obtained at low Ptot (2-4 kPa), non-oriented β-SiC bulks were obtained at mediate Ptot (6 kPa), and 〈111〉-oriented β-SiC bulks were obtained at high Ptot (10-40 kPa), exhibiting faceted, cauliflower-like and six-fold pyramid-like microstructure, respectively. The maximum Rdep of 〈111〉- and 〈110〉-oriented β-SiC bulks were 3600 and 1300 μm/h at, respectively. The activation energy obtained by the plot of lgRdep-Tdep−1 is 170 to 280 kJ mol−1, showing an exponential relation with PSi. The Vickers micro-hardness of β-SiC bulks increased with increasing Ptot and showed the highest value of 35 GPa at Ptot = 40 kPa with a complete 〈111〉 orientation.