Influence of solid lubricants addition on the tribological properties of HVOF sprayed NiMoAl coating from 30 °C to 400 °C

摘要

The present study focuses on the influence of solid lubricants (MoS2, h-BN, Cr2AlCAg) addition on the tribological properties of NiMoAl alloy in the range of 30 degrees C (Room Temperature, RT) to 400 degrees C. For this, NiMoAl and NiMoAl with 20 wt% of different solid lubricant powders were prepared and coated on a stainless steel substrate by High-Velocity Oxy-Fuel (HVOF) spraying. The coefficient of friction (COF) of NiMoAl coating at RT and 400 degrees C is 0.72 +/- 0.05 and 0.47 +/- 0.03, respectively. The addition of 20 wt% MoS2, h-BN, Cr2AlC, and Cr2AlCAg in NiMoAl reduces the COF by (50% & 30%), (47% & 45%), (37% & 49%) and (64% & 66%), respectively at RT & 400 degrees C. Characterization of the worn-out surfaces shows that the tribo-chemical by-products such as Ni3S2, Cr7C3, and Ag2MoO4 act as a friction modifier and reduces the COF. NiMoAl-20 wt% Cr2AlC coating shows a large decrease in COF with an increase in temperature. (C) 2020 Elsevier B.V. All rights reserved.