Parametric optimization and clad characterization of composite coating prepared on Ti-6Al-4V alloy using TiB[formula omitted]-Ni-Yb[formula omitted]O[formula omitted] precursor powders

Abstract

In this work, TIG cladding on Ti-6Al-4V substrate is executed by Taguchi L9 orthogonal array with three input process parameters viz.current, scanning speed and wt% of rare earth (RE). The fluctuating output responses (clad layer thickness (CLT), microhardness (MH) and wear rate (WR)) are optimized by using the desirability function analysis technique. The developed linear regression models are found highly accurate with 97.57%, 88.60% and 96.76% adjusted R2 values for CLT, MH and WR respectively. The multi-objective function of output responses is converted into a combined objective known as composite desirability (CD). The main effect on CD gives current as the most influencing factor followed by wt% of RE and scanning speed. The analysis of variance method is also applied to check the significance of input parameters on individual responses. Pair-wise input parameter variation of individual output responses are studied through contour plots. Sub-surface morphology of coating prepared at optimum condition shows dendritic, needle-like, coralline and short-columnar type microstructure with hard phases like TiB and NiTi. The aforesaid coating has a coefficient of friction of 0.24. The mechanism for wear is adhesion with ploughing and shearing of materials.