Abstract
The corrosion resistance of Ti-5%Ta-2%Nb alloy and DOCTOR (double oxide coating on titanium for reconditioning) coated titanium by O 5+ ion irradiation were compared and investigated for their corrosion behaviour. O 5+ ion irradiations were carried out at a dose rate of 1 × 10 17, 1 × 10 18 and 1 × 10 19 ions/m 2 at 116 MeV. The surface properties and corrosion resistance were evaluated by using scanning electron microscopy (SEM), atomic force microscopy (AFM), energy dispersive X-ray (EDX), glancing-angle X-ray diffraction (GXRD) and electrochemical testing methods. The results of electrochemical investigations in 11.5 N HNO 3 indicated that the open circuit potential (OCP) of DOCTOR coated titanium is nobler than Ti-5%Ta-2%Nb alloy. The potentiodynamic polarization study of Ti-5%Ta-2%Nb alloy and DOCTOR coated specimen indicated decrease in passive current density with increase in ion doses (1 × 10 17 to 1 × 10 19 ions/m 2) indicating decrease in anodic dissolution. Nyquist arc behaviour in the electrochemical impedance study substantiated the enhancement in oxide layer stability by O 5+ ion irradiation. AFM results revealed that the DOCTOR coated Ti surface was dense without gross voids, and the surface roughness decreased by O 5+ ion irradiation, but increased after corrosion test. EDX and GXRD patterns of DOCTOR coated Ti sample indicated that the coating was mainly composed of rutile TiO 2. Based on the above results, the O 5+ ion irradiation effect on corrosion behavior of Ti-5%Ta-2%Nb alloy and DOCTOR coated titanium are discussed in this paper.
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