Gun current optimization for deposition of silicon carbide films by gas tunnel type plasma spraying

Abstract

Polycrystalline silicon carbide films have been prepared by the gas tunnel type plasma spraying method (GTPS). The effect of gun current on microstructure and mechanical properties was investigated. Scanning electron microscopy, x-ray diffraction, energy dispersive spectroscopy, nanoindentation and abrasive wear were used to characterize the structure, thickness, composition and the mechanical properties of SiC films. Microstructural studies revealed the formation of cubi silicon carbide (C-SiC) at higher gun currents from 120 to 140 A. The SiC films have good-adhesion, dense, smooth and compact morphology. Determination of hardness of the SiC films by a nanoindentation technique shows that increasing gun current can improve hardness from 25.3 to 31.5 GPa. Generally, SiC film formed at higher gun currents exhibits better anti- wear resistance than that deposited at low gun current, mainly due to SiC films becoming harder. A comparison of the hardness of SiC films grown by gas tunnel type plasma spraying and SiC films grown by other methods was included. Finally, crystalline silicon carbide films with good morphology and mechanical properties have been obtained from the GTPS method that are suitable for thermoelectric and mechanical applications