High-temperature wear behavior of laser-clad composite coatings deposited on Ti6Al4V substrates

Reciprocating wear tests were performed at 25 °C, 200 °C, and 600 °C on Ni16Cr4B4Si coatings deposited on Ti6Al4V substrates by laser cladding. The wear mechanism was investigated at increasing testing temperature by analyzing changes in microstructure, phase constituents, morphology of wear track, and chemical composition of the coating surfaces. Variations in microstructure at the three temperatures were insignificant. The main constituents are dendritic Ti2Ni, interdendritic TiNi, TiC dendrites, and TiB2. At increasing testing temperature from 25 °C to 200 °C and 600 °C, part of these phases transformed into oxides. Wear resistance of the substrates was obviously enhanced by laser cladding at the three testing temperatures. Attest temperature up to 200 °C, micro-cutting evolves into a dominant micro-cutting together with a slight oxidational wear. No significant difference in wear loss was noticed. When the temperature was further increased up to 600 °C, a serious oxidation of the coating occurred resulting in a severe wear of the coating. The wear mechanism is then a combination of a strong oxidational wear and a slight micro-cutting.