Etching resistance and etching behavior of h-BN textured ceramics under Xe plasma condition

The h-BN ceramic with two-dimensional laminar structure is an important constituent material of Hall thruster channel, and the differences in its chemical bonding structures lead to anisotropy of BN grains in different orientations. In this paper, h-BN matrix textured ceramics are prepared by hot-press sintering. Xe plasma is used to etch the textured ceramics with different preparation processes and orientations. The effects of microstructure and h-BN grain orientation on plasma etching resistance of the materials are investigated. The results show that the intergranular phase has superior plasma etching resistance compared to the h-BN material. During the etching, the sample surface maintains dynamic equilibrium on the macroscopic scale, while preferential etching exists on the microscopic scale. The h-BN grains exhibit point etching, line etching and composite etching behavior during the etching process. The etching resistance of textured ceramics is related to the intrinsic plasma etching resistance of the matrix material, but less correlation to the preparation process, microstructure, and orientation of the BN grains of the matrix material, moreover, there is no anisotropic etching behavior.