Mechanical and tribological properties of high velocity oxy-fuel thermal sprayed nanocrystalline CrCNiCr coatings

One of the most important use of high velocity oxy-fuel (HVOF) thermal spray coatings is for wear resistance. In this work, the characteristics of nanocrystalline CrCNiCr coating and their effect on the mechanical and tribological properties of the material have been investigated. The objective of this study is the replacement of hazardous hard chromium plating technology used today in industry for an efficient and clean HVOF technology, using micro- and nanocrystalline CrCNiCr coatings. Commercially available, CrCNiCr powder was mechanically treated, in order to obtain nanopowders. Later, the HVOF thermal spray process was used to produce conventional and nanocrystalline CrCNiCr coatings. The coating microstructures were characterised by SEM and optical microscopy. Differences in roughness have been determined by profilometry. The ultra-microindentation technique was applied to measure the hardness and the elasto-plastic properties of the coating. In order to evaluate the friction and wear properties of different substrate materials, a pin-on-disc method has been used.