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Abstract
Double-glow plasma (DGP) coatings are recommended for metallic components to mitigate the damage induced by complex working conditions in previous studies. In this paper, Nb-rich (Cr–Nb4) and Cr-rich (Cr4–Nb) -alloyed layers were formed onto the Ti–Al substrate via a DGP process to enhance its wear resistance. Scratch and Nano-indentation tests were used to evaluate the mechanical properties of the coatings. The tribological behaviour of the coatings were investigated using a pin-on-disc tribometer by rubbing against the GCr15 ball. Results from surface analysis techniques showed that the coatings mainly comprised Cr, Nb and Cr2–Nb phases, and were well bonded to the substrate. The hardness of the Cr–Nb4 coating was 11.61GPa and the Cr4–Nb coating was 9.66 GPa which all higher than that of the uncoated Ti–Al which was 5.65 GPa. However, the critical load of the Cr4–Nb coating ~21.64 was higher than that of the Cr–Nb4 coating ~17.6. And the specific wear rate of Cr–Nb4 coating, Cr4–Nb coating and uncoated Ti–Al were 3.54 × 10−4, 0.01 × 10−4 and 1.53 × 10−4mm3 N−1 m−1, respectively. The low-wear mechanism of the coatings is discussed in detail in this paper.