Numerical Simulation of Tribocorrosion of CoCr Alloy and Ti with Galvanic Coupling in Simulated Body Fluid

The artificial hip joints have galvanic couple between femoral head made of CoCr alloy and stem made of Ti or Ti alloy, and are subjected to high levels of mechanical stress. Therefore, tribocorrosion of artificial hip joints has been frequently reported. In this study, we performed the first electrochemical numerical simulation for CoCr alloy and Ti with friction in simulated body fluid. We constructed single metal model and galvanic coupling metals model to investigate the effect of the cathodic reaction on the tribocorrosion behavior. In single metal model, CoCr alloy with friction is referred to as CoCr(Tribo.). In galvanic coupling metals model, CoCr alloy with friction in contact with Ti is referred to as CoCr(Tribo.)-Ti. In single metal model, the current density of CoCr(Tribo.) was larger than that of Ti(Tribo.). For the CoCr alloy with friction, the current density of galvanic coupling metals model(CoCr(Tribo.)-Ti) was larger than that of single metal model(CoCr(Tribo.)). The current density of both single metal model and galvanic coupling metals model increased as the increase in area of the non-friction part increased. The current density of CoCr(Tribo.)-Ti was largest, and the rate of increase in current density with the increase in area was also largest.