Friction and Wear Performance of Electroless Ni-B Coatings at Different Operating Temperatures

Abstract

Electroless Ni-B coatings are deposited on AISI 1040 steel specimens and heat treated at 350 ∘C for 1 h to improve their properties. Coating characterization is done using energy dispersive X-ray analysis, scanning electron microscope and X-ray diffraction techniques. The as-deposited coatings are amorphous and become crystalline on heat treatment. Microhardness of the coatings improves significantly on heat treatment due to the precipitation of boride phases. The tribological behavior of the heat treated coatings is observed on a pin-on-disk tribological test setup by varying the applied normal load, speed of the counterface material and the test temperature. The wear and coefficient of friction of the coatings are significantly affected by the load, speed and test temperature which in turn control the in-situ oxide formation and microstructural changes during the wear process. This is further confirmed by examining the worn specimens using scanning electron microscope and energy dispersive X-ray analysis.