Study of plasma- and detonation gun-sprayed alumina coatings using Taguchiexperimental design

Atmospheric plasma spraying (APS) is a most versatile thermal spray method for depositing alumina (Al2O3) coatings, and detonation gun (D-gun) sprayin g is an alternative thermal spray technology for depositing such coatings w ith extremely good wear characteristics. The present study is aimed at comp aring the characteristics of Al2O3 coatings deposited using the above techn iques by using Taguchi experimental design. Alumina coating experiments were conducted using a Taguchi fractional-facto rial (L-8) design parametric study to optimize the spray process parameters for both APS and D-gun, The Taguchi design evaluated the effect of four AP S and D-gun spray variables on the measured coating attributes. The coating qualities evaluated were surface roughness, porosity, microhardness, abras ion, and sliding wear. The results show that the coating quality is directl y related to the corresponding coating microstructure, which is significant ly influenced by the spray parameters employed. Though it is evident that t he D-gun-sprayed coatings consistently exhibit dense and uniform microstruc ture, higher hardness, and superior tribological performance, the attainmen t of suitable plasma-sprayed coatings can be improved by employing the Tagu chi analysis.