Tribofilms on CoCrMo alloys: Understanding the role of the lubricant. (September 2019)

• Record Type: Journal Article
• Authors: Taufiqurrakhman, Mohamad; Bryant, Michael G.; Neville, Anne
• Is Part Of: Biotribology. Volume 19(2019)
• Publication Date: 2019-09
• Subjects: Biological interfaces -- Periodicals; Biomedical materials -- Periodicals; Biomechanics -- Periodicals; Tribology -- Periodicals; 610.2805
• DOI: 10.1016/j.biotri.2019.100104
• Languages: English
• ISSNs: 2352-5738

Abstract

Abstract: The tribological activation of a passive metal alloy in an aqueous biological environment have been highlighted by many researchers; better known as bio-tribocorrosion. Tribocorrosion processes, which can be found at a number of metal-based biomedical implant interfaces, can be affected by lubricant species such as proteins, amino acids and salts. To date, researchers have quantified how the presence of organic species and the environment affect the tribological and corrosion process. However, the nature of the bio-films is still broadly to be explored. This study aims to understand how the lubricant - surface interactions influence the evolving frictional, corrosion and material volume loss from CoCrMo alloys and how the formation of any tribo-film at the interface may influence the aforementioned processes. This current research uses reciprocating tribocorrosion tests of CoCrMo surfaces in saline, protein, and protein-free cell culture medium lubricants (0.9% NaCl, 25% Foetal Bovine Serum (FBS) diluted in Phosphate Buffered Saline (PBS), Dulbecco's Modified Eagle Medium (DMEM) and 25% FBS in DMEM solutions). Results show the addition of organic constituents give a better tribology and corrosion performances. XPS confirmed that chemical reactions happened on the tested surfaces. Calcium, phosphorus and sulphur are shown to be catalysed to react in tribology-induced processes and have important roles in tribocorrosion. These results contribute to the understanding of protein-metal interactions occurring in tribofilm formation on wearing surfaces. Highlights: The presence of proteinaceous species affects the biofilm formation and friction coefficient which proved by ANOVA. The high sulphur species from DMEM, as indicated in Mo 3d XPS surface signal, tends to increase the wear resistance. SEM image shows a massive abrasive wear mechanism inside the wear track of samples in the serum-containing solution. Some proteinaceous species such as calcium, phosphorus and sulphur are tribology-induced, which is proved by XPS analysis.