Friction and wear properties of short time heat-treated and laser surface re-melted NiCr-WC composite coatings at various dry sliding conditions

Abstract

In the present study, the effect of various weight percentages (0, 20, 30, and 40 wt.%) of Tungsten Carbide (WC) reinforcement in the Nickel-Chromium (Ni-Cr) alloy was investigated. The coatings were deposited on a 316L stainless steel substrate using Plasma Transferred Arc Welding (PTAW) process. Additionally, the As Welded (AW) NiCr-WC coatings were subjected to Short Time Heat-Treatment (STHT) and Laser Re-Melting (LRM) processes and a comparative study has been carried out with that of AW coatings. X-ray Diffraction (XRD), Scanning Electron Microscope (SEM), Vickers hardness and Pin on disc wear testing facilities were employed to characterize the phase structures, microstructure, dilution, crystallization, hardness and wear properties of the deposits. Wear mechanisms were studied using the 3D surface analyzer and SEM images. The STHT and LRM coatings showed an increased hardness and more crystalline phases than the As-Welded (AW) coatings. The correlation between the intermetallic phases, residual stress, microstructural evolution and friction-wear behaviour among the AW, STHT and LRM NiCr and NiCr-WC coatings were discussed in detail.

Keywords

• Composite coating
• Crystallinity
• Hardness
• Friction and wear
• Plasma arc welding
• Heat treatment