Electrochemical aspects and in vitro biocompatibility of Ti-SS304 layered composite

Abstract

In the current research, in order to eliminate the release of toxic ions from the stainless steel 304 layer, a bi-layered Ti-SS304 biocomposite was made using the friction stir welding process, and the corrosion-cellular behavior of this biocomposite in simulated body fluid (SBF) was studied. The results show that the increasing temperature induced by increasing welding heat input during friction stir welding increases the thickness of the oxide layer formed on the titanium layer. By increasing the thickness of the oxide layer, the corrosion current density increases to 3.45 μA cm−2, the corrosion potential decreases to −0.24 V, and the corrosion rate increases to 0.029 mm/year. In addition, compared to samples fabricated with different traverse speeds of 5, 10, and 20 mm/min, the composite samples fabricated with different rotational speeds of 600, 800, and 1000 rpm did not show significant differences in corrosion current density due to competition effect of the titanium oxide layer and residual stress formed during friction stir welding by different rotational speeds. The two-layered Ti-SS304 composite fabricated at a rotation speed of 1000 rpm and a traverse speed of 20 mm/min shows the lowest corrosion current density and corrosion rate and the highest cell viability of 4.9 × 10 −7 A/cm−2, 4.26 × 10 −3 mm/year, and 92%, respectively.