Effect of synovial fluid temperature on the corrosion resistance of Ti6Al4V,Ti6Al7Nb,and CoCrMo alloys

The frictional heat generated during the operation of the joint prosthesis in vivo could change the corrosion resistance of the prosthesis material. In this paper, the corrosion behavior of three medical alloys at different synovial fluid temperatures was analyzed using electrochemical measurement technology. Furthermore, the scanning electron microscope and energy-dispersive spectrometer were used to characterize the surface morphology and composition of the alloys after long-term immersion. The results show that increasing temperature causes the open-circuit potential of titanium alloy to shift negatively and the corrosion tendency to increase. The increasing temperature leads to the decrease of activation energy of titanium alloy, which in turn results in the increase of corrosion current density and accelerated corrosion. The results of Nyquist curves confirmed that the radius of the capacitive arc decreased with the increase of temperature, indicating the deterioration of corrosion resistance. The CoCrMo alloy shows the same regularity as the titanium alloy in 0.9% NaCl, though no obvious regularity in 25% newborn bovine serum; this may be related to the complexity of the corrosion system.