Tribocorrosion response of Fe-modified titanium alloys in simulated body fluids with varying glucose concentrations

Abstract

This study evaluates the tribocorrosion behavior of Fe-modified titanium alloys (Ti-3Fe, Ti-4.5Al-1V-3Fe, Ti-6Al-1V-3Fe) in comparison with Ti-6Al-4V in Hank’s balanced salt solution (HBSS) simulating normal (0 mg/dL), pre-diabetic (100 mg/dL) and diabetic (200 mg/dL) physiological glucose conditions. Tribocorrosion tests were conducted using a reciprocating sliding configuration under open-circuit potential (OCP) and potentiostatic control (+0.5 V vs Ag/AgCl) to assess passive film stability, depassivation–repassivation kinetics and wear–corrosion synergy. Mechanical sliding induced cathodic OCP transients due to passive film rupture, with Ti-3Fe showing the largest potential drop (0.61 V, from −0.42 to −1.03 V) and negligible recovery (<0.01 V), indicating poor repassivation. In contrast, Ti-6Al-1V-3Fe and Ti-6Al-4V exhibited anodic OCP recovery of +0.059 and +0.095 V, reflecting enhanced passive film reformation. Under potentiostatic conditions, Ti-3Fe recorded peak sliding current densities of 6.4 × 10⁻ 4 A, while Ti-6Al-1V-3Fe and Ti-6Al-4V remained below 4.3 × 10⁻ 4 A, indicating higher resistance to depassivation. Increasing glucose concentration progressively destabilized the electrochemical response, with OCP fluctuation ranges increasing from 0.05 V in normal HBSS to 0.09 V in diabetic HBSS, accompanied by elevated sliding current densities and reduced post-sliding recovery. Wear analysis showed the lowest specific wear rate for Ti-6Al-4V (1.68 × 10⁻ 6 mm 3 /N·m) in normal HBSS, while Ti-3Fe consistently exhibited the highest material loss across all environments. The results show that alloy composition and glucose concentration in physiological media significantly influence tribocorrosion behavior, with Al-V-containing alloys demonstrating superior electrochemical stability and wear resistance, while Fe-rich titanium alloys exhibit greater susceptibility, particularly under diabetic conditions.