Tribological Behavior of Copper Coatings Deposited by HVAF and Cold Spray: A Comparative Assessment

This study aims to evaluate the tribological performance of copper coatings developed by high-velocity air fuel (HVAF) and cold spray (CS) which are two important low-temperature solid-state deposition processes among spraying techniques. Reciprocating sliding wear tests against alumina balls were conducted at room (25 °C) and high (300 °C) temperatures. HVAF and CS coatings showed similar friction coefficients, both with a greater friction at high temperature. However, they exhibited different wear behaviors, where HVAF coating showed increased wear depth with temperature raise, while wear depth of CS coatings remained similar. Ex situ characterizations performed from the top and cross section of the worn surfaces by SEM, EDX, and Raman spectroscopy indicated profound oxidation occurred inside the wear tracks and higher wear of HVAF coating at high temperature was mainly due to greater oxidation and more cracks inside the tribolayer.