Niobium coated Ti-Al alloy: improvement of tribological behaviour, oxidation resistance and flame retardancy

Double glow plasma (DGP) coatings were recommended for metallic components to mitigate the damage induced by complex working conditions. In this paper, A Ti-Al alloy was coated with niobium (Nb) via a DGP process to enhance its anti-oxidation properties, wear resistance and flame retardancy. The results showed that the Nb-coated Ti-Al alloy mainly comprised Nb, AlNb2, AlMoTi2 and β-Ti phases. Room temperature sliding-friction tests indicated that the Nb-coated Ti-Al alloy exhibited a stable friction coefficient of an average value of 0.25, whilst the same value for via the uncoated Ti-Al alloy was around 0.45. High-temperature oxidation tests revealed compact oxide grains without cracks after the 100 h test, indicating good oxidation resistance. An ablation test showed that the Nb-coated Ti-Al alloy exhibited excellent flame retardancy, with the ablation time of the Nb-coated Ti-Al alloy at 1.62 times that of the uncoated Ti-Al base alloy. The alloys tribological behaviour, oxidation resistance and flame retardancy mechanisms are discussed in detail in this paper.