Corrosion behavior of titanium boride composite coating fabricated on commercially pure titanium in Ringer's solution for bioimplant applications.

Abstract The boriding of commercially pure titanium was performed at 850 °C, 910 °C, and 1050 °C for varied soaking periods (1, 3 and 5 h) to enhance the surface properties desirable for bioimplant applications. The coating developed was characterized for the evolution of phases, microstructure and morphology, microhardness, and consequent corrosion behavior in the Ringer's solution. Formation of the TiB 2 layer at the outermost surface followed by the TiB whiskers across the borided CpTi is unveiled. Total thickness of the composite layer on the substrates borided at 850, 910, and 1050 °C for 5 h was found to be 19.1, 26.4, and 18.2 μm respectively which includes 2 layer. The presence of TiB 2 phase was attributed to the high hardness ~ 2968 Hv 15 gf of the composite coating. The anodic polarization studies in the simulated body fluid unveiled a reduction in the pitting corrosion resistance after boriding the CpTi specimens. However, this value is > 0.55 V SCE (electrochemical potential in in-vivo physiological environment) and hence remains within the safe region. Both the untreated and borided CpTi specimens show two passive zones associated with different passivation current densities. Among the CpTi borided at various times and temperatures, a 3 h treated shows better corrosion resistance. The corrosion of borided CpTi occurred through the dissolution of TiB 2 .