Wear resistant TiMoN coatings deposited by magnetron sputtering

TiMoN coatings with different Mo concentrations were deposited using a reactive magnetron sputtering technique and characterized by X-ray diffraction, nano-indentation, pin-on-disc testing, SEM/EDS and X-ray photoelectron spectroscopy. Mo alloying of TiN coatings generally enhances hardness. When tested in a pin-on-disc test against WC-Co pin, the coefficients of friction of TiMoN coatings were found to decrease with the increase in Mo atomic fraction, with the lowest values (0.4-0.5) being only one-half that of TiN coating (1.03). The underlying mechanism of the Mo effect is the formation of lubricious MoO₃ on the wear track. The combination of low coefficient of friction and enhanced hardness reduces the wear rate of TiMoN coatings to less than 2.5% of the wear rate of TiN coating.