Corrosion fatigue in DLC-coated articulating implants: an accelerated methodology to predict realistic interface lifetime
Pardo, A.; Ilic, E.; Thorwarth, K.; Stiefel, M.; Hauert, R.
Science and Technology of Advanced Materials 2019, 20 (1), 173-186.
We present amethodology to accelerate and estimate the lifetime of an interlayer under dynamic loading in body-likemedia. It is based on accelerating corrosion fatigue processes taking place at the buried interface of a Si-based adhesion-promoting interlayer in articulating implants on a CoCrMo biomedical alloy; the implants are coated with diamond-like carbon (DLC). The number of interface loading cycles to delamination is determined by reciprocal loading in corrosive fluid. Its dependence on the load is summarized in a Wöhler-like curve of a DLC/DLC-Si/CoCrMo system in body working conditions: cyclic stresses at 37 °C in phosphate buffered saline (PBS). The presence of oxygen as a contaminant strongly affects the lifetime of the interface under corrosion fatigue. The main parameters acting on the prediction, with a special emphasis on simulated in vivo conditions, are analyzed and discussed: the media (PBS, Milli-Q water, NaCl, Ringers’ solution and bovine calf serum), the load, the frequency and the composition of the interface determined by X-ray photoelectron spectroscopy.