Tribocorrosion behavior of DLC-coated Ti-6Al-4V alloy deposited by PIID and PEMS + PIID techniques for biomedical applications

Abstract

One of the main drawbacks observed from the usage of titanium alloys implants is the premature failures due to excessive wear and corrosion. Among the surface modification alternatives, Diamond-like carbon (DLC) coatings appear as a promisor candidate, since it has an amorphous structure chemically inert with desirable properties and still is a solid lubricant. Dense DLC coatings on biomaterials could be obtained by advanced vapor deposition techniques as the plasma immersion ion deposition (PIID) and the plasma enhanced magnetron sputtering (PEMS). This work aims to investigate the tribocorrosion behavior of DLC coatings systems, obtained by PIID only and PEMS+PIID hybrid techniques, applied on Ti-6Al-4V alloy samples for biomedical applications. The tribocorrosion tests were performed under phosphate-buffered saline (PBS) solution on the DLC-coated samples and compared to a Ti-6Al-4V bare alloy sample. Besides tribocorrosion tests, it were performed X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, scanning electron microscopy (SEM), nanoindentation and scratch tests to evaluate the microstructure, morphology, mechanical properties and adhesion of the DLC-coated samples, respectively. The tribocorrosion tests demonstrated at least 5 times less friction coefficient and less than 2% of wear rate DLC-coated samples compared to Ti-6Al-4V bare alloy sample. Nevertheless, the results show that DLC coatings deposited by the advanced plasma enhanced techniques are very promissory to improve tribocorrosion behavior in Ti-6Al-4V alloy implants.