High Temperature Oxidation Characterization Of Arc-sprayed Composite Coatings

With the development of modern industry, hot corrosion of material, especially the high-temperature oxidation and its resistance is more and more important.The oxidation resistance of metal materials mainly depends on the properties of the oxide formed on the metal surface. To estimate the oxidation resistance, arc-sprayed aluminum coatings and FeCrAl/Al composite coatings at 800℃, 900℃were studied in this dissertation, and the rule of oxidation resistance is studied through drawing relation curves between thickness of diffusion coatings and soaking time. In order to analyze the behavior of atoms between coatings and substrate at high temperature, by using scanning electron microscopy (SEM), electron probe micro analyzer (EPMA) and X-Ray diffraction analyzer, the rule of the diffusion of elements and interinfluence, the change of the structure of coatings and the formation of the intermetallic compound during heating are analyzed.The results of the experiments revealed that the thickness of the diffusion increases with the increase of the temperature and the warming hours, the metallurgical bonding of FeCrAl/Al composite coatings increase the reliability of bond between coatings and substrate, as well as the aluminum amount, and melt and diffusion of coatings at high temperature make it deeply penetrate and seal the pore of the FeCrAl coatings, which make great sense to the resistance system. Both Al coatings and FeCrAl /Al composite coatings are effective to the high temperature oxidation resistance, especially the composite coatings. Comparing with the unpore-sealed coatings, the pore-sealed coatings have advantage to seal the pore and the diffusion of oxygen, which increase the oxidation resistance of coatings.When the specimens coated with aluminum were heated at high temperatures, an intermetallic compound Fe₂Al₅, which is the most, was formed on them, and increases as the diffusion goes. The pores formatted during heating are analyzed, the pores increase and then link together, and pore-seal could decrease the formation of the pores, which makes great sense to the bonding between coatings and substrate.