A grey-fuzzy Taguchi approach for optimizing multi-objective properties of zirconium-containing diamond-like carbon coatings

Metallic, diamond-like carbon (Me-DLC) coatings are widely used in the mold industry due to their excellent wear resistance. In this paper, zirconium-containing DLC (Zr-DLC) coatings are prepared using an unbalanced magnetron sputtering process. Factors that affect the wear resistance of coatings consist of friction coefficients, hardness and anti-sticking properties. This paper aims to develop a method that optimizes the multi-objective properties of Zr-DLC coatings. For statistical purposes, the experimental parameters for the Zr-DLC coatings were put in place with a L18(35) orthogonal array. In order to optimize these properties, a method combining the grey, fuzzy and Taguchi approaches was established. While using the developed grey-fuzzy Taguchi method (GFTM), the experimental results from four properties can be integrated into a performance index. A comparison of the integrated performance index between the initial and optimal conditions shows that the magnitude increases from 0.46 to 0.81. The gain for each property by the GFTM from the initial condition is reported as 35% positive.