Microstructure and tribological properties of <111>-oriented 3C-SiC by chemical vapor deposition

Highly <111>-oriented 3C-SiC coatings were fabricated by chemical vapor deposition method at different temperatures. As deposition temperature increased from 1473 K to 1773 K, the surface structure of <111>-oriented 3C-SiC transitioned from hexagonal structure with sixfold symmetry to hill-like structure, and finally to conical porous surface composed of stacked short rods. Owing to alteration of surface structure, the hardness of 3C-SiC coatings presented a trend of initially increasing and subsequently decreasing. The 3C-SiC coating deposited at 1673 K possessed the highest hardness, with a value of 42.08 GPa. The average friction coefficient for 3C-SiC/Si 3 N 4 pair ranged from 0.258 to 0.569. The wear rate and hardness exhibited opposite trends. Compared with 3C-SiC coatings prepared at the other three temperatures, the 3C-SiC coating deposited at 1573 K exhibited the lowest wear rate under loads of 5 N, 10 N, and 15 N. Furthermore, the lowest wear rate, recorded at 15 N, was 4.1 × 10 −6 mm 3 /Nm, attributed to high hardness and uniform grain size. The wear mechanism of <111>-oriented 3C-SiC coatings during dry sliding primarily involved fracture, leading to fatigue and third-body wear.