Evolution of surface morphology, roughness and texture of tungsten disilicide coatings on tungsten substrate

Abstract

The hot dip silicon-plating method is considered as a promising surface coating technology. However, the correlation between the process parameters and the WSi2 coatings properties is unclear entirely. In this work, the SEM, TEM, AFM combining with EBSD methodology are applied to study the evolution behavior of surface and interface morphologies, roughness and texture of tungsten disilicide coatings. The coating mainly consists of WSi2 outer layer and W5Si3 interface layer, HDS coating presents a smooth surface and dense interface. AFM results show that the particle distribution on the coating surface is homogeneous with a small surface roughness (Ra = 124.57–422.67 nm). It is observed that at low deposition times, the surface morphologies are more homogeneous with lower surface roughness and vice versa. EBSD results show that the orientation of the columnar WSi2 grains in the coating is perpendicular to the W substrate, the grain diameter of WSi2 range from 7.45 to 10.67 μm, and has a significant preference orientation on (100) and (110) crystal planes. This is mainly attributable to the vigorous bombardment from the high energy Si ions prevents the formation of the lowest energy (111) crystal plane orientation.