Microstructure and tribo-mechanical properties of APS-sprayed NiAl/Cr₂AlC composite coatings with various additions of self-made Cr₂AlC

The microstructures, tribo-mechanical properties of the fabricated NiAl/Cr₂AlC composite coatings with various additions of self-made Cr₂AlC were comparatively investigated. The results indicated that appropriate addition (10 wt%) of Cr₂AlC could improve the microstructure, hardness, bending strength and tribological performance of the coatings. However, excessive addition of Cr₂AlC led to the loose structure, decreased bending strength and adhesive strength of the coatings. The added Cr₂AlC played a critical role of lubrication and wear resistance at low and medium temperatures due to its layered structure, leading to the low COFs and wear rates. At higher temperatures, the Cr₂AlC accompanied with the generated oxides such as Al₂O₃, Cr₂O₃ and NiO played a critical role of antifriction and anti-wear, resulting in the significant reduced COFs and wear rates. The NiAl/Cr₂AlC composite coating with the Cr₂AlC addition of 10 wt% exhibited excellent tribological performance from room temperature to 800 °C.