Tribological behavior of polyurethane-based composite coating reinforced with TiO2 nanotubes

The unmodified and hexamethylene diisocyanate (HDI) modified TiO2 nanotubes, were used for fabricating TiO2 nanotubes (TiNTs)/polyurethane (PU) composite coating. The effects of applied load and sliding speed on the tribological behavior of the composite coating were investigated using a block-on-ring wear tester. Compared to the TiO2 nanotubes filled PU composite coating, the HDI modified TiO2 nanotubes (TiNTs–HDI) filled one had the lower friction coefficient and higher wear life under various applied loads and sliding speed. Scanning electron microscope (SEM) investigation showed that the TiNTs–HDI filled PU coating had smooth worn surface under given applied load and sliding speed, and a continuous and uniform transfer film formed on the surface of the counterpart ring, which helped to reduce the wear of the coating. The improvement in the tribological properties of TiNTs–HDI/PU composite coating might due to an improvement in interfacial adhesion between TiNTs and PU after HDI treatment. The strong interfacial coupling of the composite coating made TiNTs–HDI not easy to detach from the PU matrix, and prevented the rubbing-off of PU composite coating, accordingly improved the friction and wear properties of the composite coating.