| Thermal spray technology plays an important role in surface engineering field. Spray materials (powder or wire) are melted or partly melted by flame, electric arc or plasma plume and propelled onto the substrate by compressed gas. The sprayed coating can improve the surface properties of material, such as wear resistance, corrosion resistance and thermal insulation capability. In addition, the original sizes of the worn components can be restored by means of thermal spray. The feedstock wires perform the function of self-consuming electrodes and compressed air is propelling gas in the electric arc spray. The electric arc spray is widely used in fields of corrosion protecting, repairing, manufacturing and preparing functional coating because of high efficiency, low cost and minimized thermal impact on the components.The main structure of passenger train includes train body and train bogie which are made of carbon steel. The steel usually is coated with paint to avoid corrosion during train operation. But the result is not satisfying. Therefore, new techniques are needed to improve the corrosion resistance of the passenger train steel structure.In this paper, the electric arc spray was used to solve this problem. The microstructural features and mechanical properties of the stainless steel (1Cr18Ni9Ti) coating with B-01 (FeCr alloy) as bond coating and aluminum coating prepared with varied parameters were investigated. And the optimum electric arc spray parameters were obtained through comprehensive experiment. The corrosion resistance of the aluminum coating (with sealed surface and without), stainless steel coating (with sealed surface and without) and paint coating were tested in the experiment. In this study, the XDP electric arc spray equipment, scanning electric microscope (SEM), X-ray diffraction (XRD), corrosion experimental machine, video analyzer (VIDAS), etc. were used. The results show that the stainless steel (1Cr18Ni9Ti) coating is mainly composed of austenite and a little ferrite. The coating has lamellar structure and includes pores and oxides. The aluminum coating also has lamellar structure and is looser resulting from increased pores and oxides compared with stainless steel coating. The features of electric arc sprayed coating are relation with the coating formation mechanism. First, the feedstock material is melted and pulverized by compressed air. The molten particles are accelerated by the compressed air or electric arc and impact onto the surface of the substrate with high momentum. The deposition of an individual molten particle formed a splat by the process of impacting, rapid cooling and solidification. Then, the process mentioned above is repeated when the following particles impact the substrate, which easily results in a lamellar structure. On the other hand, the material will be oxidized during the spray process in atmospheric environment. And there are unmelted or partly melted particles deposited in the coating, which also contributes to the pores and oxides in the coating. Considering the aluminum is more active compared with the stainless steel, it is understandable that there are more pores and oxides in the aluminum coating.Spray electric voltage, spray electric current and spray distance have obvious effects on the microstructure and mechanical properties of the coating. The low voltage and low current mean the low power of electric arc. This will lead to poor melting of feedstock material, which increases the porosity of the coating. Vese versa, increased voltage and current will contribute to the low porosity of the coating. But the extremely high voltage and current also have negative effects on the porosity of the coating. The voltage and current has similar effects on the bonding strength and microhardness of the coating. Within the scope of study, the bonding strength and microhardness increase with increasing electric voltage and electric current and then decrease when the parameters exceed some point. When spray distance is small (less than...
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