Wear behaviour of borided α, α+β and β Titanium alloys

This study aims to compare the wear properties of borided biomedical-grade titanium alloys, namely Cp-Ti, Ti-6Al-4V and Ti-45Nb, from basic classes each possessing α, α+β and β crystalline structures, respectively. The work also focuses on identifying the wear mechanisms that occur during tribological testing. Wear tests were conducted on surface treated samples under conditions that yielded maximum thickness and hardness values. A pin-on-disk tribometer with reciprocating motion, using a WC-Co ball as the counterface, was employed for dry sliding wear tests. Wear resistance was evaluated through wear track measurements and weight loss methods. Morphological features, microstructure of tested surfaces and also the debris generated were also analysed. At loads up to 12 N, mild polishing wear with shallow scratches and no detectable weight loss was observed across all titanium alloys. The Ti-45Nb alloy exhibited the most severe wear at 17 N due to the thinner boride layer, higher surface roughness, lower hardness and adhesion strength, resulting in premature degradation. Above 17 N, signs of delamination, microcracks, and chipping appeared to some extent in Cp-Ti and Ti-6Al-4V alloys, primarily ascribed to fatigue wear. However, no weight loss was recorded across all tested loads, indicating superior wear resistance.