Mechanism of tribofilm formation on Ti6Al4V oxygen diffusion layer in a simulated body fluid

Abstract

An Oxygen Diffusion Layer (ODL) was generated on the surface of Ti6Al4V alloy by thermal oxidation treatment. In vitro tests for cytotoxicity were performed in the presence of Ti6Al4V and the ODL samples with the culture of G292 Cells using MTT assay. The results showed a similar cell viability in the presence of the both samples. Wear behaviour of Ti6Al4V and the ODL samples was investigated in a phosphate buffered saline solution under a normal load of 30N at a sliding velocity of 0.1m/s. The worn surface and subsurface of the samples were studied using SEM, STEM, TEM, XPS, AFM, nano-hardness and surface profilometry. A bio-tribofilm was observed on the worn surface of the ODL. TEM studies showed that the tribofilm had an amorphous structure and contained oxygen and phosphorous as confirmed by XPS and EDS analysis. AFM images also revealed that the tribofilm consisted of compacted fine debris. The formation of the tribofilm on the ODL with higher hardness and strength resulted in a decrease of about 95% in the wear rate compared with Ti6Al4V alloy.

Microstructure analysis, tribological correlation properties and strengthening mechanism of graphene reinforced aluminum matrix composites

“…7 . In a corrosive environment, aluminum matrix composites tend to react with oxygen in the electrolyte, forming an oxide film that affects the subsequent process 23 . This film can be used as the surface strengthening layer, which is the source point of staggered enrichment and increases the internal stress of the material 24 .…”

Correlation between the formation of tribofilm and repassivation in biomedical titanium alloys during tribocorrosion

“…Additionally, a region exhibiting dark contrast was heterogeneously distributed on both worn surfaces, the extent of which was larger at the slower sliding speed. It is known that the organic matter has poor conductivity and so would exhibit dark contrast in the SEM, and previous studies suggest that the dark region on the worn surface could be attributed to the formation of protein-enriched tribofilm [24][25][26] or an oxide film or both [27,28]. A more detailed investigation of the tribofilm is described later.…”