OPTIMIZATION OF EROSION–CORROSION BEHAVIOR OF NICHROME COATED 2205 DUPLEX STAINLESS STEEL USING GREY RELATIONAL ANALYSIS

Abstract

Erosion–corrosion is a common mechanism in the degradation of systems in the mining, chemical, and petrochemical industries. Surface modification can help to reduce the detrimental effects of erosion–corrosion. This study uses the plasma spray process for coating nichrome on duplex stainless steel (DSS2205) to improve the surface characteristics. Erosion tests were performed to analyze the effect of parameters such as impact velocity (150, 175 and 200[Formula: see text]m/s), impact angle (30∘, 60∘and 90∘), and erodent particle discharge rate (2.5, 3.75 and 5[Formula: see text]g/min). According to the findings, the maximum erosion rate ([Formula: see text][Formula: see text]g/g) was found at a flow velocity of 200[Formula: see text]m/s and 30∘impact angle with a discharge rate of 2.5[Formula: see text]g/min. While the minimal erosion rate was observed at a low velocity of 150[Formula: see text]m/s, 90∘impact angle, and 5[Formula: see text]g/min discharge rate. Electrochemical polarization studies were carried out on the eroded specimens using a corrosive solution containing 3.5% NaCl. Corrosion potentials and current densities were estimated from polarization graphs using the Tafel extrapolation method. The erosion–corrosion properties of the samples were subjected to metallurgical characterization to evaluate the influence of nichrome plasma coatings to assess the potential causes of failure. The grey relational analysis (GRA) was further used for improving the erosion–corrosion process parameters and found the optimum solution as flow velocity of 150[Formula: see text]m/s, 30∘impact angle with a discharge rate of 5[Formula: see text]g/min. The validation test confirmed an increase of 20–30% in grade when using the optimum process parameters.