Synthesis of MCrAlY/YSZ coatings by plasma spray method on the inconel 738 substrates and investigating of their hot corrosion behavior

One of the most important methods to prevent the failure of materials in high temperatures is using thermal barrier coatings (TBC). Hot corrosion is the most important reason of thermal barrier coatings failure. Synthesis of an interface composite layer between bond coat and top coat could be so useful to increase their hot corrosion resistance. In this study, hot corrosion behavior of two kinds of TBC synthesized by APS were investigated: 1) Common TBC (MCrAlY, YSZ) 2) Multi layers FGM (Functionally graded materials), TBC (MCrAlY, 50%YSZ+50%MCrAlY, YSZ). Hot corrosion tests were carried out on the coatings surface in the molten salt of 45%Na2SO4+55%V2O5 mixture at 1050 °C for 20 hours. Microstructure, morphology and chemical composition of the surface and cross section of the coatings were investigated by SEM equipped with EDS. XRD analysis was used to study microstructure and hot corrosion products. The results indicated that the hot corrosion resistance of FGM, TBC was much better than normal TBC due to the formation of AlVO4 and CrVO4 phases in this kind of coating during the hot corrosion test.