Optimization of Quench Polish Quench (QPQ) Coating Process Using Taguchi Method

Abstract

In this research, the thickness of coating layer and hardness of coated 316L stainless steel surface has been improved by Quench Polish Quench (QPQ) coating process. The influences of nitriding Temperature(T), nitriding time(tc), and Oxidation time(to) on hardness and thickness of coated surface have also been investigated using Taguchi method. During this process, the percentage of carbonate and cyanate, post oxidation temperature, and time are constantly maintained. The experimental investigations have been performed using the Taguchi analysis to examine the effects and to predict the combination of optimum processing time settings. The nitriding time and temperature are significantly contributed to the hardness and maximizing the thickness respectively. The level-3 of all process parameters has been recommended to maximize the hardness (800 Hv) and layer thickness (19.6 µm). The microstructure of the Layer thickness on the coated stainless-steel surface has been illustrated using a Scanning Electron Microscope (SEM) image.