Submersible pump abrasion resistant surface protection technology requirements

Study of metallic coatings
Protection technology in submersible pump abrasion resistant surface is also widely used in metal surface protective layer. Use the most is the welding rod and wire coating. Using the welding method of stainless steel welding rod can ensure the welding layer and the substrate has a high bonding strength, but the dilution rate of welding process is large, and the thickness of the welding layer is not uniform and the machining allowance is large. By surfacing welding process of the surface of the submerged pump blade, the general in the welding department did not happen before the cavitation damage, the solder joints around the pile and the rapid occurrence of new cavitation damage, until the bottom of the surfacing layer. The stainless steel spray coating formed by wire spraying is mainly based on mechanical bonding, which is not suitable for the shock loading and anti cavitation of the submersible pump. For some large submersible pump such as the workpiece, large diameter (diameter 3 meters) axial flow pump impeller chamber, can be embedded in the surface layer of stainless steel to increase abrasion resistance. But this method will be sent to a large workpiece submersible pump factory specialized in processing, cutting, welding, mosaic, expensive, long cycle, non general submersible pump can pump out. Alloy powder coating is developed on the basis of on-line material spraying. Compared with the welding process, the formation of beautiful appearance, easy to control the thickness, the dilution rate is small, the method is simple, the heat source is easy to get, processing is not affected by climate, site restrictions. But because the spraying layer is composed of high speed jet to semi molten alloy powder particles on the surface of the substrate layer is formed by stacking rules, which belongs to the layered structure, with the direction of their physical characteristics, and in the spraying process, each powder particles are condensation occurs, shrinkage and deformation phenomena and development a kind of internal stress in the coatings, the alloy powder coating generally used for small and medium sized submersible pump cavitation and abrasion of the surface protection is not too serious.
Surface protection materials and process requirements
The material surface protection technology must have 1 anti abrasion coating: (1) high strength and hardness, resistance to cavitation abrasion; (2) has a toughness, to absorb impact energy; (3) has a very high bond strength, to ensure that the coating in the pump high speed impact the water 30-35 meters per second without peeling; (4) coating material must be moderate in price, in order to ensure the promotion and use in large and medium-sized submersible pump and the large volume of rural small submersible pumping station; (5) coating material should be non-toxic, non flammable, explosive materials, convenient storage and transportation, do not pollute the surrounding environment.
The processing requirements in order to ensure the promotion and application of surface protection technology, processing technology must be: (1) has the advantages of simple process, can have different degrees of the operator; (2) used in processing tools (appliances) should be in the market to buy or is necessary for general pump maintenance work, and the price is moderate, without special and expensive equipment; (3) the process should not be affected by the seasons and the surrounding environment, to ensure the pump station in winter and spring maintenance periods; (4) coating does not require special maintenance, after coating can fast curing or put into use, to shorten the maintenance period.
Development of alloy powder spray welding technology
Spray welding technology is a kind of metal surface protection technology developed on the basis of spraying and surfacing with the development of the low melting point powder material. The spray layer through the remelting process, coating density without holes, smooth surface, has the advantages of material saving, good quality and high efficiency, the surface hardness of spray welding layer can be as high as HRC60-70, can flow part several times or even ten times to extend the service life of the pump, diving.
Optimization of spray welding alloy powder materials
The optimal points in order to ensure the quality of spray welding layer, prevent workpiece deformation and cracking of the coating, coating materials research technical route optimization: (1) through the optimized size, particle size, phase change hardening and the number of crystal grain size, in order to obtain a reasonable organization form and distribution structure. (2) according to the characteristics of submersible pump cavitation, abrasion, the performance index to adjust the material, can ensure material with excellent abrasion resistance, and can minimize or reduce the cracks, improve the weldability. (3) to determine the reasonable technical parameters and process parameters, to improve the condition of the use of the coating.