Tribological performance of thermally molded UHMWPE coated PEEK under simulated physiological conditions: A taguchi based experimental investigation

Abstract:

Polyetheretherketone (PEEK) and ultra high molecular weight polyethylene (UHMWPE) are widely recognized for their mechanical robustness and tribological performance in biomedical applications. PEEK offers high compressive strength and stiffness, while UHMWPE provides excellent wear resistance and low friction. This study aimed to combine these attributes by fabricating thermally molded UHMWPE coatings on PEEK substrates and evaluating their tribological performance under simulated physiological conditions. Coatings were prepared using a mild steel mold and thermal molding at 150 °C, followed by machining and remelting to improve density. Pin on disc tribological tests were conducted in Ringer’s solution using a Taguchi L9 design of experiments with sliding speed, sliding distance, and normal load as factors. Unexpectedly, UHMWPE coated PEEK exhibited higher wear compared to monolithic PEEK and UHMWPE. Statistical analysis confirmed that coating integrity, rather than intrinsic material properties, governed tribological performance. Weak interfacial bonding, thermal contraction mismatch, and third body abrasion were identified as key mechanisms. These findings highlight the importance of coating adhesion and fabrication techniques in biomedical tribology. Future work should focus on surface treatments, interlayers, and advanced coating processes to enhance interfacial integrity.