Preparation of NiAlW coating by APS and HVOF spraying: Microstructure evolution, mechanical properties, and high-temperature tribological behavior

The wear-resistant NiAlW coatings were prepared using atmospheric plasma spraying (APS) and high-velocity oxygen fuel (HVOF) techniques, respectively. The microstructure, mechanical properties, and tribological performance of the coatings were studied, and the wear mechanisms were explored. The results showed that the NiAlW coatings produced by both techniques are primarily composed of the NiAl phase, with the HVOF-prepared coating exhibiting higher density, hardness, and adhesive strength. In the wear test at 200 °C–800 °C, the friction coefficient (COF) and wear rate of APS-prepared coating (A-NiAlW) and HVOF-prepared coating (H-NiAlW) showed a trend of first increasing and then decreasing. At low temperature of 200 °C, A-NiAlW coating was mainly abrasive wear and oxidation wear, while H-NiAlW coating was mainly abrasive wear and adhesion wear. When the temperature rose to 400 °C, both coatings faced relatively serious adhesive wear, resulting in an increase in COF and wear rate. Under high-temperature conditions, the significant generation of self-lubricating phases such as NiAl₂O₄ and NiWO₄ provided good lubrication effects, effectively reducing wear and resulting in excellent tribological performance for both coatings at elevated temperatures.