Insight into the Hot Corrosion Behavior of FeMnCrSi/TiC Coatings at 900 °C

Abstract

This study explores the deposition of an Fe-MnCrSi/TiC coating on 45 steel surfaces using high-velocity arc spraying technology, examining the microstructure and hot corrosion behavior of the resultant layer. The microstructure of the FeMnCrSi/TiC coating primarily consists of an α-Fe (BCC) solid solution, composed of Fe, Mn, Cr, Si, C, and other elements, with a minor presence of β-Fe (FCC) solid-solution phase and unmelted TiC particles. Following 100 h of cyclic 900 °C hot corrosion, Mn on the coating surface preferentially oxidizes, forming a manganese-rich oxide layer. This process reduces the oxygen partial pressure (O2) within the coating, prompting the formation of a dense Cr2O3 layer on the inner side of the oxide layer. Concurrently, the rapid diffusion of Mn and Cr elements triggers the generation of Mn- and Cr-deficient regions at the metal/oxide layer interface, inducing the transformation of the coated metal primary matrix from an FCC + BCC dual phase to an α-Fe (BCC) single phase. After the reaction, the hot corrosion weight gain of the coating reached 12.43 mg/cm2, approximately one-fourteenth of the weight gain of the 45 steel substrates. This weight gain adheres to the parabolic law, suggesting that the FeMnCrSi/TiC coating exhibits excellent corrosion resistance under the given conditions.