TRIBOLOGICAL BEHAVIOR OF ELECTROLESS Ni–P COATINGS IN VARIOUS CORROSIVE ENVIRONMENTS

Abstract

The present paper deals with the study of tribological characteristics, viz. friction and wear, of electroless Ni–P coating in corrosive environments (brine, acidic and alkaline) by varying different coating process parameters as well as varying the tribological testing parameters, viz. applied load and speed. The optimized results of coating process parameters for minimum friction and wear performance of the coating are presented. Moreover, a detailed study of the tribological behavior of the coating is undertaken individually for the three corrosive environments. The results obtained are compared among each other and also with the dry condition test of the coating. It is found that the friction coefficient of Ni–P coating decreases with increase in load for all environments. In case of wear, the wear rate of Ni–P coating gradually increases with increase in load for all mediums but the same decreases after 40[Formula: see text]N in brine and alkaline mediums. However, for acidic solution, the wear rate shows a continuous increasing trend. It is observed that alkaline and brine environments are favorable from friction and wear point of view of the coating, respectively. Microstructure study of the coatings is also performed and the coating is found to be of cauliflower-like morphology. The coating also exhibits amorphous structure in as-deposited condition, which gradually turns crystalline with heat treatment.