Surface modification for orthopaedic titanium alloy by wide-area electron beam

Wide-area electron beam (WAEB) irradiation was proposed as a new surface-finishing process for orthopaedic titanium alloy products. The surface roughness could be reduced from R-z = 10 mu m to R-z = 0.7 mu m all over the wide circular surface within a diameter of 60 mrn in just a few minutes under optimum electron beam conditions. In this paper, the surface structure and the surface characteristics of WAEB-irradiated surface are discussed. The crystal grain size becomes small and the microstructure in the surface vicinity changes under WAEB irradiation. The corrosion resistance and the repellency can be improved simultaneously with the surface smoothing. Therefore, the WAEB irradiation method enables highly efficient surface smoothing and surface modification of orthopaedic titanium alloy.