This study presented the application of Taguchi designed experiments to optimize 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 L18 factorial orthogonal array experiment, and the effects of control parameters on the surface properties were critically evaluated in the experiments. The surface anti-wear properties by optimal design have been studied comparatively. By optimization from Taguchi S/N ratios and analysis of variance, the surface wear volume values are decreased by 37%. It was clear that anti-wear performance estimations of HVOF sprayed WC-Co coatings are greatly improved by way of the optimal experiment, and these findings achieved the desired values in the WC-CO coatings. The experimental results indicated that the proposal method offers an effective and efficient approach for developing a robust and highly quality HVOF sprayed WC-Co coating.

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 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.

This study presented the desirability function based on Taguchi designed experiments to solve multiple responses statistical optimal problems for the tungsten carbide/cobalt (WC-Co) coatings of high-velocity-oxygen-fuel (HVOF) processes. The eight control factors based on L18 arrays were conducted and the multi-responses of wear-resistant coatings such as hardness, deposited thickness and wear rate were evaluated simultaneously in the desirability-based experiments. Based on desirability analysis, the optimal settings have been identified, and the impacts of control factors are determined by analysis of variance on the multi-responses. Further, a confirmation run was conducted to validate the tests. Experimental results have shown that the hardness increased by 16.61% and the deposited thickness improved by 10.50%, while the wear rate decreased by 34.03%. It was clear that confirmation tests are greatly improved by way of the desirability-based multi-responses on HVOF WC-Co experiments, and these findings achieved the desired values on wear-resistant coatings. The proposed procedure was applied at HVOF sprayed WC-Co experiments, and the implementation results demonstrated its feasibility and effectiveness to maximize hardness, make a target of deposited thickness value and minimize wear rate by a HVOF.