Development of high hard TiB–TiB2 coatings on Ti implants for bio-tribological applications; applying Box-Behnken design and actual wear analyzing in simulated body fluids

This research focuses on the enhancement of the tribological behavior of commercial pure titanium (Cp-Ti) in a simulated body fluid (SBF) via surface reinforcement by titanium borides. The protective boride coatings were formed through the pack cementation process at two different temperatures (950 and 1050 °C) to create diverse hard compositions of TiB and TiB–TiB 2 in the coating, with hardness of 1032 and 1291 Hv, respectively. The roughness and wettability of top surfaces were evaluated before the tribology studies due to their impacts on the tribology behavior. Box-Behnken design (BBD) was applied to investigate the effects of the wear parameters in dry and SBF environments. The duration of the wear tests was 53, 35, and 26 min for low, medium, and high speed. It was found that the abrasion wear type was dominant at the beginning of sliding, and then changed to the plastic deformation in the dry conditions, while there is no sign of the abrasion and adhesion wear features at the surface of the reinforced samples abraded in the SBF solution. Results confirmed a high coincidence between BBD predictions and actual findings. The released debris from the coatings was also investigated to find origins. Results showed that majority of the debris in the SBF solution belonged to the calcium phosphate particles demonstrating the bioactivity of the TiB–TiB 2 coatings. According to findings, hard TiB–TiB 2 coatings could significantly improve the tribological behavior of the Ti implants, which could in turn result in expanding the biological application of Cp-Ti. • Two types coating was applied on CP-Ti; TiB and TiB–TiB 2 . • Wear resistance and friction coefficient was pre-evaluated by BBD method. • The predicting models had a good coincidence with the actual results. • Tribological behavior of coatings in SBF confirmed the biological essentials.