Multi-Attribute Optimization of a Ceramic Coating on Super Duplex Stainless Steel Using Hybrid Taguchi – GTMA – Utility Technique

In the current research, high velocity oxy-fuel coating of Aluminium Titanate (Al2TiO5) is given to super duplex stainless steel (UNS S32760) by varying two controlling parameters viz. Headstock speed and Carriage speed. Investigation is carried out on the material for Coating Thickness, Coefficient of Friction, Wear Rate, Pitting Potential and Fatigue Life. The coefficient of friction on the substrate is 0.07, while it is in the range of 0.35 to 0.52 for the coated specimens. During the coating process, though TiO2 reduced porosity, α-Al2O3 phase formation due to heating caused surface pores resulting in a rougher surface with increased coefficient of friction. The wear rate decreased by about 95% in all coated scenarios due to the ceramic coating's high abrasion resistance. Pitting potential increased by about 11% for coated specimens as Titanium in the coating material enhanced the corrosion resistance. SEM micrographs of the coated specimens exposed surface pores which acted as crack initiation sites and reduced fatigue life by about 7% when compared to uncoated specimen. The results were analyzed by employing Hybrid Taguchi - Graph Theory Matrix Approach - Utility technique to identify and optimize the comprehensive utility of the responses. This method also predicted the responses very close to the confirmation test results.