Sliding and Abrasive Wear Behavior of Mo-Ni Plasma Sprayed Coatings

Wear is one of the problems most commonly associated with industrial components. Its cost to industry is high and the recognition of this fact lies behind the continuous development of materials and processes and post deposition techniques for mitigating tribological losses. The aim of this study was to investigate of microstructural and mechanical properties of Ni-Mo plasma sprayed coatings with and without post heat treatment. Wear tests were performed by means of a tribometer in block-on-ring configuration in air, at room temperature under lubricated conditions. Different loads and different sliding speeds have been used. The results were compared with cast iron blocks. Nylon was used as a counterpart. The influence of post-treatment on the coating’s sliding resistance was thus investigated. Abrasion wear resistance is determined by rubber wheel test in accordance with ASTM G-65. The microstructure and worn scars of the coating were evaluated by surface profilometer, scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDX) and X-ray diffraction (XRD). The sliding and abrasion wear mechanisms of the coatings was consequently discussed. Hardness distribution on the cross-section of the coating was also determined. The results indicated significant alteration of the coating microstructure, brought about by the coating post-treatment, particularly flame post heated. Significant effect of load and sliding speed on both the coefficient of friction and wear rates of coatings has been observed.