LAUSR

Abstract Tantalum carbide (TaC) coatings deposited using DC reactive sputtering, have been scrutinized with XPS, XRD, TEM, nanoindenter, and tribological tests in ambient air and simulated body fluid (SBF). The carbon (C) content of the coatings gradually increases from 30.3 to 74.3 at.%, along with a phase transition from hexagonal-Ta2C through cubic-TaC to nanocomposite structure consisting of cubic-TaC nanocrystallites surrounded by amorphous matrix, while at the highest C content, the coating only consists of amorphous phase. The hardness (H), elastic modulus (E) and the ratio of H/E for the coatings increase firstly and then decrease with increasing C content. Tribological tests demonstrate that the nanocomposite coatings possess superior wear resistance and strong self-lubrication effects with a friction coefficient as low as 0.19 in ambient air and below 0.15 in SBF. While the wear rate of Ti6Al4V coated with TaC coatings with 65.3 at.% C shows the lowest value of 1.44 × 10−6 mm3/Nm in SBF, which is only one fifth compare with the naked Ti6Al4V. The biocompatibility test confirms that the TaC nanocomposite coatings exhibits no toxicity and good cytocompatibility. Thus, the nanocomposite TaC coatings could be used as wear resistant layer between the bearing components of total hip joint replacements.