The paper describes response surface methodology (RSM) based on design of experiments and analysis of variance (ANOVA) as a statistical design while developing a robust plasma transfer arc (PTA)coating process. Based on ANOVA, The relative important parameters with respect to surface at hardness values were identified in the Taguchi design, where they were further used in predictors. In addition, we applied three-dimensional graphs in RSM to develop a robust PTA response surface yielding the desired-better area of a treated layer. In this study, a quadratic polynomial with a Box-Behnken design is utilized. The results reveal that RSM provides the effective methods as compared to the traditional trial-and-error method for exploring the effects of controlled factors on response. A very good agreement was observed, as evidenced by R-squared value, 90%, between the predicted and the experimental data, and its error percent is found to be approximately 3.801% in the PTA-coating process. It is clear that RSM model demonstrated better accuracy in predicting surface hardness for PTA-coating process. Accordingly, RSM based on design of experiments was used as statistical PTA-coating design tools combined with the hardness model. Device zone optimization and yield enhancement have been demonstrated.

This study reported on Taguchi-Fuzzy logic model with statistical experiments to characterize the tungsten carbide/cobalt (WC-Co) deposited quality properties of the high-velocity oxygen-fuel (HVOF) process. The eight control factors were designed in a factorial orthogonal array experiment, and the effects of control parameters on the integrated surface properties were critically evaluated in the Taguchi designed experiments. A fuzzy logic system with knowledge bases in the inference engine was used to explore the relationships between variables and responses in the modified structures. In addition, the structure and properties of HVOF sprayed WC-Co coating were reported. Furthermore, a confirmation experiment of the optimal process was conducted. It was clear that HVOF sprayed WC-Co coating estimations are greatly improved through the Taguchi-Fuzzy logic operation, and these findings achieved the desired values in the modified properties.

This study reports on the Grey relational system, with a statistical experiment to enhance the quality characteristics of yttria stabilized zirconia (ZrO2/8%Y2O3)coatings made by a plasma-sprayed process. The eight control factors were designed in an L18 factorial orthogonal array experiment, and the effects of the control parameters on the surface properties were critically evaluated in the experiments. The characteristic terms- surface roughness, porosity, hardness, and wear volume in the sprayed ZrO2/8%Y2O3 coatings through the optimization- were studied comparatively. A grey relational system, based on the Taguchi orthogonal experiment for optimizing multi-responses in the modified properties, was reported. In addition, the influence of control factors on the grey relational system for spraying processes was investigated by analysis of variance. In addition, a confirmation experiment was conducted. Experimental results have shown that the hardness increased by 31.19%, while the surface roughness decreased by 40.67%, the porosity was reduced by 53.53%, and the wear rate improved by 24.21%. It is clear that the quality characteristics for plasma sprayed coatings are greatly improved through grey relational analysis, and that these findings achieved the desired values in regard to the modified properties.