The microstructures and corrosion behavior of cladding layer on Ti-6Al-4V alloy using arc deposition with Ar and CO2 mixed shield gas

Abstract

The surface modification of Ti6Al4V in biomedicine aims at the regeneration and healing of bones. It prolongs the service life, which is the basic understanding of friction and corrosion occurring at the biomaterial/human fluid interface. To modify the Ti6Al4V surface, CO2 was added to the shielding gas during the arc cladding process so that the strengthening phase TiOx and TiC were obtained in the cladding layers. A continuous cladding layer is obtained on the surface of Ti6Al4V without any pores and slag inclusions. After adding CO2 in the shielding gas, a large amount of TiOx and TiC are obtained in the cladding layers. As the amount of TiOx phase and TiC phase increases in the cladding layer, the microhardness gradually increases from 350HV to about 600HV. The effect of electrochemical corrosion of different cladding layers was studied in 3.5% NaCl solution using tafel polarization curves and electrochemical impedance spectroscopy(EIS). With the increase of the CO2 flow rates in the shielding gas, the value of Icorr gradually decreases from (5.12 ± 1.1) × 10−8 A/cm2 to (2.45 ± 0.5) × 10−8 A/cm2, and the pits on the corroded surface are gradually reduced, which indicates that the corrosion resistance of the cladding layers is gradually improved.