A significant improvement of the wear resistance of Ti6Al4V alloy by a combined method of magnetron sputtering and plasma electrolytic oxidation (PEO)

• Published in: Surface & coatings technology Vol. 358; pp. 879 - 890
• Main Authors: Kang, Shi-hang, Tu, Wen-bin, Han, Jun-xiang, Li, Zhi, Cheng, Ying-liang
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 25.01.2019; Elsevier BV
• Subjects: Aluminate; Biocompatibility; Chromium steels; Electrolytes; Industrial applications; Magnetron sputtering; Oxidation; Plasma electrolytic oxidation; Protective coatings; Surgical implants; Ti6Al4V alloy; Titanium alloys; Titanium base alloys; Tribology; Wear; Wear rate; Wear resistance; Aluminate; Magnetron sputtering; Plasma electrolytic oxidation; Wear; Ti6Al4V alloy
• ISSN: 0257-8972; 1879-3347
• DOI: 10.1016/j.surfcoat.2018.12.025

Titanium alloys own a series of advantages such as low density, high specific strength, and biocompatibility. However, the poor wear resistance of titanium alloys impedes their wide applications in industry. In this study, we show that the wear resistance of the Ti6Al4V alloy can be greatly improved by a combined method of magnetron sputtering and plasma electrolytic oxidation (PEO). An ~13 μm pure aluminum layer was first applied on the Ti6Al4V alloy by magnetron sputtering and then PEO was employed for the second step treatment of the Al coated Ti6Al4V alloy. The PEO of the Al coated Ti6Al4V was carried out in aluminate (32 g l−1) and silicate (16 g l−1) electrolytes, respectively. Ball-on-disc tribological tests with an applied load of 10 N against a Cr steel ball were used to evaluate the wear performances of the samples. The coating formed in 32 g l−1 aluminate electrolyte for 4 min shows superior wear performance, which sustained 1800 s sliding time against the steel ball and the wear rate is non-detectable. In contrast, the coating formed in the silicate electrolyte for 15 min has been destroyed during the tribological test, showing a wear rate of ~3.9 × 10−4 mm3/(N·m). The excellent wear performance of the coatings formed in the aluminate electrolyte can be attributed to its high growth rate and homogeneity in microstructure. The coating growth mechanisms have also been discussed. •Wear protection to Ti6Al4V alloy via combined method of magnetron sputtering and PEO•The combined methods significantly improved the wear performance of the alloy.•Best protection was afforded by PEO in a concentrated aluminate electrolyte.