Tribo-Mechanical Properties and Corrosion Study of Nano Zirconia Reinforced Electroless Ni-B Coatings

Abstract

The present investigation deals with studying zirconia-reinforced electroless Ni-B coatings deposited on mild steel substrates. The addition of ZrO2 nanoparticles is assisted by ultrasonication, which helps form a uniform colloidal solution, which is then added to the coating bath. The coatings are deposited in varying zirconia concentrations (1 g/l, 5g/l, 10 g/l, and 15 g/l). The deposited coatings are investigated for Vicker's microhardness, elastic modulus, friction, wear, scratch width, and corrosion resistance. The results of the deposited coatings are also compared with binary Ni-B coatings. The coating with a zirconia concentration of 10 g/l in the bath shows the most promising result. This coating shows a decreased specific wear rate of nearly 1/3rd compared to the binary Ni-B coating. The coating with a zirconia concentration of 10g/l also shows improved corrosion resistance. The Ecorr of the coating shows an increase of approximately 13% towards a nobler value compared to the unreinforced coating (binary Ni-B coating). The same coating also shows an increase in the elastic modulus to nearly 14 % as compared to the binary Ni-B coating. The scratch width of the coating with 10 g/l zirconia concentration is minimum among the coatings under study. It is also observed that the above-mentioned properties deteriorated upon increasing the concentration of the nano-zirconia in the bath beyond 10 g/l.