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Chemical vapor deposition; Coatings; Compaction; High resolution transmission electron microscopy; Layered semiconductors; Molybdenum compounds; Nanocrystals; Single crystals; Textures; Wear of materials, Basal textures; Coating microstructures; Nano indentation; Nanocrystallines; Physical vapor deposited; Structural compaction; Structural reorientation; Upscaling; Wear behaviors; Wear-testing, Tribology
Abstract:
Industrial upscaling frequently results in a different coating microstructure than the laboratory prototypes presented in the literature. Here, we investigate the wear behavior of physical vapor deposited (PVD) MoS2 coatings: A dense, nanocrystalline MoS2 coating, and a porous, prismatic-textured MoS2 coating. Transmission electron microscopy (TEM) investigations before and after wear testing evidence a crystallographic reorientation towards a basal texture in both samples. A basal texture is usually desirable due to its low-friction properties. This favorable reorientation is associated to a tribological compaction of the porous specimens. Following running-in, sliding under high contact pressure ultimately leads to a wear rate as small as for an ideal grown bulk MoS2 single crystal grown by chemical vapor deposition (CVD). This suggests that the imperfections of industrial grade MoS2 coatings can be remediated by a suitable pretreatment. © 2022 The Authors