Abstract
To improve the surface performance, Nylon12/Polyamide-imide (PAI) composites were coated on aluminum substrates using a printing technique. Dimples were formed on the surface of the coating with sizes corresponding to the grain diameters of the nylon particles. The objective of this study was to investigate the influence of the dimples on the tribological behavior under oil lubrication. The effect of the sliding speed on the friction coefficient was also evaluated. Friction tests were performed using a ball-on-disk tribometer. The results revealed that the incorporation of dimples significantly improves the tribological properties. Particularly, the friction coefficients of the Nylon12/PAI composite coatings were much lower than that of the PAI-only coating at slow sliding speeds. The dimples played an important role in maintaining the oils under mixed lubrication. The friction coefficients of the Nylon12/PAI composite coatings initially decreased with an increase in the additive amount of nylon particles. However, the friction coefficients gradually increased when the volume fractions of Nylon12 exceeded about 3 to 5 vol. %. Based on tribological behavior, it was found that an optimum amount of nylon particles exists for PAI coatings.
