Pump cavitation, wear protection technology research and development achievements

Cavitation, abrasion and the joint damage of the pump have always been an important issue in the operation, maintenance and management of the pump. The traditional surface protection materials and processes are far from meeting the requirements of the pump for cavitation and erosion resistance. In order to enhance the ability of anti-cavitation and abrasion on the surface of pump overcurrent parts, besides constant use of stainless steel or other cemented carbide to manufacture blades and impellers, the surface protection technology is continuously tested. This article describes its progress are as follows: Surface protection technology research status Introduction to surface protection technology Non-metallic coatings in China in the 20th century, 60, 70 began to epoxy resin and its compounds used in water pump anti-erosion protection. In the 1980s have also developed a composite dragon coating, polyurethane coating imitation ceramic coating and rubber coating and other non-metallic coatings. In addition, there are some non-metallic coatings formed using materials such as quick-acting titanium rubber, rubber, enamel, ceramic, glass and the like, which are less used due to complicated processing techniques and the like. In the 1990s, the United States also introduced the United States devcon fixatives, arc composite coatings, synthetic rubber and other polymer materials. These non-metallic coating materials in pumping station harsh environment, often due to the coating and the metal matrix bonding ability and the material itself is not enough hardness, it is difficult to achieve the desired anti-cavitation, anti-erosion effect. Metal coating research in the pump anti-erosion surface protection technology is also widely used metal surface protection layer. The most widely used is electrode surfacing and wire coating. The use of stainless steel electrode surfacing method to ensure that the welding layer and the substrate with a high bonding strength, but the surfacing fade rate, the welding thick and uneven processing margin, the solderability of the work of the substrate material demanding . The surface of the pump blade treated by the surfacing welding method is generally subjected to new cavitation destruction immediately around the surfacing spot until no cavitation damage occurs at the surfacing zone until the bottom of the surfacing layer. The stainless steel spray particle coating formed by wire spraying is mechanically combined, which is not suitable for the pump impact load and anti-cavitation repair. For some large-scale pump workpieces, such as large diameter (more than 3 meters in diameter) axial-flow pump impeller chamber, a stainless steel plate can be inlaid on the surface to increase the anti-abrasion ability. However, this method needs to be sent to large-scale pump plant specialized processing, turning, inlaying, welding, expensive, long cycle, non-ordinary pumping station can be implemented. Alloy powder coating is developed on the basis of wire spraying. Compared with the surfacing method, the molding is smooth, the thickness is easy to control, the fading rate is small, the method is simple, the heat source is easily obtained, and the processing is not limited by the climate and the site. However, since the sprayed layer is formed by regularly stacking alloy powder particles in a semi-molten state sprayed onto the surface of a substrate at a high speed and in a layered structure, the physical properties of the sprayed layer are directional and, in each spraying process, Powder particles are condensation, shrinkage, deformation and other phenomena in the coating to develop an internal stress, so the alloy powder coating is generally only used for cavitation and abrasion less serious surface protection of small and medium-sized pumps.