Remanufacturing projects require specific key technologies as support. Advanced surface engineering, as well as nano-surface engineering technology is one of the most important key technologies in remanufacturing. Thermal spraying technology is an important component of (nano) surface engineering. It is the essence of the material to be sprayed to the molten or semi-molten state, and then under the action of high-speed pressure gas jet quickly into the matrix, and finally by the collision deformation and accumulation forming. There are many kinds of thermal spraying methods, including high-speed arc spraying and supersonic plasma spraying applications. Nano-structured coatings can be prepared by supersonic plasma spraying.

Study on High Temperature Corrosion and Erosion of Intermetallic Coatings by High Speed ??Arc Spraying

Large-scale power plant boiler water wall pipe work environment is very bad, hot corrosion is very serious. The boiler fuel is coal, coal contains S, K, Na, V and other impurities, in the formation of SO2, SO3, H2S, V2O5, etc., and the air O2, NaCl and other reactions in the pipeline surface deposition of molten salt, thus Accelerated corrosion of materials.

The high Ni-Cr alloy coating can effectively prevent hot corrosion by spraying the pipe wall, but the method is costly and difficult to popularize. Fe-Al intermetallic compound structure coating can be widely used to reduce the anti-oxidation and anti-vulcanization performance, corrosion resistance in a variety of media, high high temperature strength, low density, especially low cost Hot corrosion damage.

However, the low plasticity and low fracture resistance of Fe-Al intermetallic compounds at room temperature deteriorate their forming process performance, which greatly limits their engineering applications. In order to overcome the shortcomings of Fe-Al intermetallic compound molding process, high-speed arc spraying and powder core wire (iron-coated iron-aluminum mixed powder) combination of materials preparation and forming integration technology, in the laboratory successfully prepared Fe -Al intermetallic compound and its composite coating (Fe-Al, Fe-Al / WC, Fe-Al / Cr3C2). The results show that Fe-Al intermetallic compounds and their composite coatings have excellent heat and corrosion resistance and erosion wear properties. Fe-Al intermetallic compounds are known as “poor stainless steel”.

As the cooling rate is different, the flat particles in the coating are mainly composed of sub-microcrystals and microcrystals. The nanocrystalline structure appears in the local area, and a small amount of amorphous phase is found. The dislocation density of the grains is high.

The Fe-Al intermetallic compound prepared by high-speed arc spraying and its composit  coating have been applied to the heating surface of the naval vessel boiler pipeline and the parts of the exhaust pipe of the tank and armored vehicle exhaust pipe.

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