Corrosion behaviour of triode plasma diffusion treated and PVD TiN-coated Ti-6Al-4V in acidified aqueous chloride environments

The corrosion resistance of triode plasma-nitrided and oxynitrided Ti-6Al-4V was investigated in a hydrochloric acid solution using potentiodynamic polarisation, cyclic voltammetry, and immersion testing at OCP. The untreated and the PVD TiN-coated alloy were used as benchmarks. When compared to the untreated alloy and a PVD-TiN coating, the diffusion treated alloys proved to be more durable due to the presence of a Ti2N compound layer. The corrosion barrier properties of the nitrided alloy depend on both thickness and integrity of the nitride compound layer; the thicker the layer, the better the performance in these tests.