Effects of grain size and crystallographic orientation on plasma etching behavior in tungsten carbide

The plasma etching behavior of tungsten carbide (WC) ceramics was thoroughly investigated with an emphasis on the effects of grain size and orientation. The WC ceramics with submicron- and micron-scale grains were compared to assess the influence of grain size on the etching rate, surface roughness, and microstructural response under plasma exposure. The grain size had a minimal effect on the etching rate, but significantly affected the post-etch surface morphology . WC with smaller grains retained the smoother surface after etching, while larger-grained WC exhibited the plateau-like topography caused by a preferential grain etching. To determine the etching preference of individual grains, electron backscatter diffraction (EBSD) and atomic force microscopy (AFM) analyses were conducted on the WC ceramics with micron-scale grains. The analysis revealed that the etch rate was strongly influenced by the crystallographic orientation and (0001) and (-12−10) planes showed the slow etch rate with low surface roughness.