Biotribological Performance of Multilayer Ti- and Mo-Based MXene Coatings

Abstract

Metallic materials are extensively utilized in biomedical implants due to their excellent strength and corrosion resistance. However, friction and wear-related issues remain important challenges in load-bearing implant applications. To address these concerns, multilayer Ti3C2T x , Mo2TiC2T x , and Mo2Ti2C3T x coatings were deposited onto stainless steel substrates in two distinct thickness ranges (lower: similar to 100 to 150 nm; higher: similar to 225 to 275 nm) and biotribologically tested under simulated body fluid lubrication conditions. Our results revealed that low coating thicknesses of Mo2TiC2T x demonstrated the most favorable biotribological performance, reducing the wear rate by up to 33% and consistently lowering the coefficient of friction, with reductions of up to 56% compared to uncoated references, owing to their ability to form durable tribo-films under SBF lubrication. In contrast, Ti3C2T x coatings increased friction and wear under considered conditions, while Mo2Ti2C3T x showed a moderate COF reduction but higher wear rates, particularly at higher coating thicknesses and loads. These findings emphasize the superior self-lubricating properties of Mo2TiC2T x coatings, thus highlighting their potential to enhance the durability and longevity of load-bearing biomedical implants.