Construction of a tribocorrosion test apparatus for the hip joint: Validation, test methodology and analysis

In biomedical research, because of the critical nature of corrosion within the environment of motion and interactions of weight bearing surfaces, scientists and engineers have shown a growing interest in the area of “ tribocorrosion” . Fundamentally, tribocorrosion combines the disciplines of tribology and corrosion and their concurrent exchanges. Principles of tribocorrosion are applied in a range of industries including the offshore, space and biomedical (for example, dental and orthopedic) industries. One of the challenges in tribocorrosion research is the lack of standard testing equipment and methodologies, particularly in its bio-medical applications. Many investigators and research laboratories are engaged in modifying their existing classical tribology apparatus, whether they are commercially available or customized tribometers, to integrate electrochemical monitoring. The current work is focused on developing a tribocorrosion test apparatus to model the contact situation of artificial hip joints with particular attention on possible erroneous issues that could arise in such a system. The test system facilitates studies on the tribocorrosion behavior of implant metals or coatings as a function of diverse tribological and electrochemical parameters, and allows monitoring temperature, pH and dissolved oxygen level during testing. Initial results on the HC CoCrMo alloy in bovine calf serum (BCS), indicate that the proposed system is reliable and useful for the investigation of tribocorrosion behavior of implant materials. Electrochemical impedance spectroscopy tests (EIS) are employed before and after the sliding tests. The usefulness of such tests in understanding the changes in the surface chemistry and corrosion kinetics are explained, with the help of optimum EIS models. An attempt has also been made to highlight the relevance on wear quantification methods and possible ways to analyse the synergistic interactions of wear and corrosion for the biomedical tribosystems in orthopedics and dentistry.