High Temperature Self-lubricating Propertiesin Ni-P-Ag-Al2O3 Hybrid Nanocomposite Coating

Self lubricating coatings are one of the conventional protective coatings in aerospace and power plant industries which have the suitable stability and performance at high temperature. In this research, co-deposition of alumina and silver particles within Ni-P electroless coating were implemented on mild carbon steel substrate. The effect of heat treatment on the hardness of the coatings was investigated and morphology and cross section of the coatings were evaluated by Scanning Electron Microscopy (SEM). The tribological behavior of the coatings was evaluated by pin-on disc method and by using 52100 steel pins at ambient and high temperature and the wear rate was measured by 3d optical profiler. Also, lubrication mechanism was investigated by using energy dispersive spectroscopy analysis (EDS) and wear track micrographs. The results showed that the wear resistance and lubrication of Ni-P-Ag-Al2O3 hybrid coating were increased simultaneously and high temperature self-lubricating characteristics of the hybrid coating have been enhanced by the diffusion of silver through the coating and the production of silver-rich tribofilms.