Spray welding is to reheat the preheated self-dissolving alloy powder coating to 1000-1300 ℃, so that the particles are melted, slag is formed and floated to the surface of the coating, and the generated borides and silicides are dispersed in the coating, so that the particles Good bond with the substrate surface.
The final deposit is a dense metal crystalline structure and forms a metallurgical bonding layer of about 0.05-0.1mm with the matrix. Its bonding strength is about 400MPa, and it has good impact resistance, wear resistance and corrosion resistance, and has a mirror-like appearance.
Compared with the spray coating, the advantages of the spray coating are significant. However, due to the local heating of the matrix during the remelting process, the temperature reaches 900 °C, which will cause large thermal deformation of the parts.
Therefore, the scope of application of spray welding has certain limitations. Parts and materials suitable for spray welding are generally:
① Under the impact load, the vulnerable parts with high surface hardness and good wear resistance are required, such as sand blasting machine blades, crusher tooth plates, excavator bucket teeth, etc.;
②Large wearing parts with relatively simple geometry, such as shafts, plungers, sliders, hydraulic cylinders, chute plates, etc.;
③ Low carbon steel, medium carbon steel (with carbon content below 0.4%), structural steel containing manganese, molybdenum, and vanadium less than 3% in total, nickel-chromium stainless steel, cast iron and other materials.
