Evaluation of tribological properties and optimization of electroless Ni-P-W coating under dry condition using grey fuzzy analysis

Abstract

Electroless Ni-P-W coating has enhanced tribological properties compared to the conventional binary alloys. Hence, electroless Ni-W-P, which is a ternary alloy, is synthesized on mild steel substrates. The coatings are heat treated at 400 °C for 1 hr to obtain a high hardness. Their tribological behavior is investigated on a pin–on–disc tribo–tester under dry condition. Three test parameters which include the applied normal load (L), sliding speed (S) and sliding time (T) are varied and their effects on wear depth and coefficient of friction are analyzed. An attempt is made to ascertain the optimum combination of the parameters that would minimize the coefficient of friction and wear depth of the deposits simultaneously using Grey Fuzzy logic. Optimum tribological behavior of the deposits is obtained at an applied normal load of 10 N, sliding speed of 80 rpm and sliding duration of 5min. Load and time are seen to be the most significant factors in influencing the friction and wear of the deposits. The variation of coefficient of friction and wear depth considering the combined effect of the aforesaid parameters is analyzed from three dimensional surface plots. The wear mechanism is found to be predominantly abrasive in nature.