Investigation of interaction of extreme pressure additive, load and sliding speed parameters with silver nano-particles in wear environment

Abstract

This study aims to minimize the wear of brass-based sliding bearing materials by using extreme-pressure and nano-silver added lubricants. The nano-fluids used in the experiments were characterized by the Zeta test, size measurement, absorbance graphs, wettability analyses and TEM imaging. The effect of extreme-pressure (5%, 10% and 15%) and nano-silver (1%, 5% and 9%) concentration ratios and the interaction of lubricants with load and speed parameters were analyzed with ball-on-plate wear experiments. The results were analyzed by evaluating the friction coefficient and wear volume values, as well as SEM and 3D topography images. It has been found that 5% extreme pressure lubricant reduces friction coefficient by 32.82% and volume loss by 89.51% compared to base lubricant. According to the results, the lowest friction coefficient (0.0276), volume loss (0.042 mm3) values and the best surface images were obtained at 1% concentration. Furthermore, the tribological performance decreased as the concentration of extreme-pressure and nano-silver increased, and optimum extreme-pressure and nano-silver concentrations were obtained as 5% and 1%, respectively. Using additives, different load (10N, 20N and 30N) and speed (10 rpm, 25 rpm, 40 rpm) parameters, Taguchi’s L9 fractional factorial experimental design was created for interaction analyses. With the Taguchi analysis of the design, 5% extreme pressure added lubricant, 10N load and 40 rpm speed parameter combination was determined as the optimum test condition and base lubricant, 30N load and 25 rpm speed parameters were determined as the worst test condition. According to the variance analyses results, it was determined that the lubricant condition was the most effective parameter on the coefficient of friction (67.79%), volume loss (51.07%) and surface roughness (45.43%).