Tribocorrosion behavior at the taper–trunnion interface of artificial hip prostheses with different femoral head materials

Tribocorrosion damage at the taper–trunnion interface of artificial hip prostheses restricts their effectiveness and service life. Existing investigations on the tribocorrosion mechanism primarily relied on simplified ball-on-disk models. They neglected the inherent complexity and uniqueness of the loading and motion conditions at the real taper–trunnion interface. This study aimed to use a hip joint simulator to conduct a comparative investigation of the tribocorrosion behavior of Ti6Al4V femoral stems paired with traditional ball head materials of CoCrMo alloy and zirconia-toughened alumina (ZTA) ceramics as well as with the innovative material zirconium–niobium (ZrNb) cermet in an attempt to simulate real physiological conditions. The results indicated that material loss in all three pairings was primarily dominated by wear. The CoCrMo–Ti6Al4V pairing demonstrated the largest material loss, whereas the ZTA–Ti6Al4V and ZrNb–Ti6Al4V pairings demonstrated comparable, but much smaller, material loss. This could be explained by the difference in variations in the wear and corrosion behavior among different material pairings. Furthermore, CoCrMo–Ti6Al4V pairing led to galvanic corrosion, thereby increasing the corrosion susceptibility. The ZTA ceramics and ZrNb cermet with electrical insulation properties maintained a lower corrosion susceptibility. The ZTA–Ti6Al4V and ZrNb–Ti6Al4V pairings demonstrated a similar material loss in terms of mechanical wear, which was slightly lower than that with the CoCrMo–Ti6Al4V pairing. The relatively low hardness of CoCrMo alloy made it susceptible to the plowing effect induced by oxides during tribocorrosion, leading to substantial material loss and damage. Conversely, the ZTA ceramics and ZrNb cermet ball heads showed significantly limited damage because of their high hardness. Thus, the CoCrMo–Ti6Al4V pairing demonstrated a much greater wear-induced material loss. In conclusion, the tribocorrosion performances of ZTA–Ti6Al4V and ZrNb–Ti6Al4V pairings were comparable and significantly superior to that of CoCrMo–Ti6Al4V pairing.