Effects of counterface material and UV radiation on the tribological performance of a UHMWPE/CNT nanocomposite coating on steel substrates

A nanocomposite tribological coating of ultra high molecular weight polyethylene (UHMWPE) reinforced with 0.1 wt% single-walled carbon nanotubes (SWCNTs), is developed. The effects of different counterface materials and UV radiation on the mechanical and tribological properties of the nanocomposite coating are investigated. Three different counterface materials, silicon nitride, AISI 52100 bearing steel and brass, in the form of Ø4 mm balls are used. Ball-on-disk wear tests are conducted at a load of 4 N and a rotational speed of 2000 rpm. It is observed that the nanocomposite coating exhibits lower coefficient of friction when slid against brass as compared to that against silicon nitride or steel balls. It is also observed that in all the three material cases, the nanocomposite coating did not wear after the initial running-in period, wherein the asperities on the coating deformed plastically and got smoothened. Furthermore, the tribological properties of the nanocomposite coating did not alter even after being exposed to UV radiation at an intensity of 0.71 W/m2 nm for 300 h.