Tribological Performance Optimization of Electroless Nickel Coatings Under Lubricated Condition

Abstract

The present chapter aims to determine optimal tribo-testing condition for minimum coefficient of friction and wear depth of electroless Ni-P, Ni-P-W and Ni-P-Cu coatings under lubrication using grey relational analysis. Electroless Ni-P, Ni-P-W and Ni-P-Cu coatings are deposited on AISI 1040 steel substrates. They are heat treated at suitable temperatures to improve their hardness. Coating characterization is done using scanning electron microscope, energy dispersive X-Ray analysis and X-Ray diffraction techniques. Typical nodulated surface morphology is observed in the scanning electron micrographs of all the three coatings. Phase transformation on heat treating the deposits is captured through the use of X-Ray diffraction technique. Vicker's microhardness of the coatings in their as-deposited and heat treated condition is determined. Ni-P-W coatings are seen to exhibit the highest microhardness. Friction and wear tests under lubricated condition are carried out following Taguchi's experimental design principle. Finally, the predominating wear mechanism of the coatings is discussed.