Evaluation of Tribological Characteristics of Atmospheric Plasma Spray Deposited Ni-Based Coatings

Present investigation attempted to explore the tribological properties of atmospheric plasma sprayed coatings. In order to assess the role of solid lubricants, different weight percentages (5, 10, and 15 wt.%) of silver (Ag) were taken, whilst MoS₂ concentration remained fixed. Dry sliding wear tests were conducted for different specimens namely, Ni-Al-MoS₂-5 wt.% Ag (NA5), Ni-Al-MoS₂-10 wt.% Ag (NA10) and Ni-Al-MoS₂-15 wt.% Ag (NA15) at different loads of 4, 9, 14 & 19 N, and slid speed of 0.3 m/s under room temperature (RT) conditions. It was observed that coefficient of friction (COF) and wear rate of specimens decreased as the load increased till 14 N, and beyond that increasing trend was noticed. However, the NA10 specimen has revealed the best tribological properties in terms of minimum COF (0.48) and wear rate (4.7 × 10⁻⁵ mm³/Nm) at 14 N and 0.3 m/s. The synergy of Ag and MoS₂ on the frictional properties of specimens have been well explained with the help of worn surface morphologies and some useful conclusions were made.