Selection principle of wear-resistant coating spraying material

       According to the difference in the use environment of the wear-resistant coating, different spraying materials and spraying processes should be selected, such as:



(1) Coating for soft support. This type of coating allows abrasive particles to embed and also allows deformation to adjust the bearing surface. The spraying materials are mostly non-ferrous metals; such as aluminum bronze, phosphor bronze, babbitt and tin coating. Specific application parts such as: Babbitt bearings, hydraulic press bushings, thrust bearing bushes, compressor cross slides, etc.



(2) Coating for hard support. Hard bearing surfaces typically operate under high load and low speed conditions and are typically used where embeddability and self-adjustment are not critical, and where lubrication is limited. The spraying materials can be selected from nickel-based, iron-based self-fluxing alloys, oxide and carbide ceramics (such as Al2O3-TiO2, Co-WC, etc.), refractory metal Mo and Mo plus self-fluxing alloys. Specific application parts such as: punch shock absorber crankshaft, anti-chafing bushing, rudder bearing, turbine shaft, driving gear journal and piston ring fuel pump rotor, etc.



(3) Wear-resistant particle wear coating. When the operating temperature is lower than 540°C, the coating should be able to withstand the cutting and furrowing action of foreign abrasive particles, and the hardness of the coating should exceed the hardness of the abrasive particles; the coating material can be selected from self-fluxing alloy plus Mo or Ni/Al mixed powder, High chromium stainless steel, Ni/Al wire, T8 steel and self-fluxing alloy plus Co/WC mixed powder. Specific application parts such as: mud pump piston rod, polishing rod bushing, screw conveyor of concrete mixer, tobacco grinding hammer, mandrel, grinding and polishing fixture, etc.



When the use temperature of the wear-resistant particle wear coating is between 538 and 843 °C, the coating requires a hardness exceeding that of the abrasive particles at high temperature, and must also have good oxidation resistance. Iron-based, nickel-based, Cobalt-based spray materials (such as cobalt-based Cr, Ni, W alloy powder, Ni/Al wire, austenitic low-carbon stainless steel, nickel, cobalt self-fluxing alloy, etc.) and Cr3C2 cermet powder; when subjected to shock or vibration load, If the temperature is lower than 760℃, the self-fluxing alloy is the best; when the corrosion is serious, it is best to use Cr3C2; if it is mainly used for anti-oxidation, iron, nickel, and cobalt-based coatings can be used.



(4) Hard surface abrasion resistant coating. When the operating temperature is below 538°C, wear is due to the fact that when the hard surface slides on the softer surface, the hard protrusions groove the soft surface and cause scraping out of debris, which has the same effect as abrasive particles. In this case, the coating is required to be harder than the matching surface, and some iron-based, nickel-based, cobalt-based spray materials, self-fluxing alloys, non-ferrous metals (such as iron-added aluminum bronze), oxide ceramics, tungsten carbide and certain Some refractory metal coating materials. Application specific parts such as drawing capstans, brake sleeves, shift forks, plug gauges, tube sizing perforators, extruded films, guide rods, paddle knives, drums, blade crushers, fiber guides, forming tools and pump seals circle etc.



When the service temperature of the hard surface wear-resistant coating is 540~815℃, although the basic situation is the same as above, the wear will be aggravated at high temperature, so cobalt-based self-fluxing alloy, Ni/AI and chromium carbide should be used. coating material. When the temperature is lower than 760 ℃ and there is impact load, self-fluxing alloys should be used; Cr3C2 coatings should be used when the temperature is higher; Ni/Al should be used for anti-oxidation. Specific application parts such as: forging tools, hot crushing rolls, hot forming dies, etc.



(5) Anti-fretting wear coating. Since wear is usually caused by unpredictable fretting, when the operating temperature is less than 540 °C, a coating with better toughness should be selected, such as self-fluxing alloys, oxides, carbide cermets, some Ni, Fe, Co-based spray materials and non-ferrous metals, etc. Specific application parts such as: servo motor pivots, cam followers, rocker arms, cylinder liners, air guards, guide vanes, propeller reinforcement rods, etc.



When the working temperature of the anti-fretting wear coating is 538 ~ 843 ℃, due to the high working temperature, specific iron-based, nickel-based, cobalt-based materials and metal chromium carbide ceramic materials can be used. Specific application parts such as: turbine airtight rings, airtight rings, airtight gaskets and turbine blades of jet engines.



(6) Cavitation resistant coating. Because the coating has to withstand the gas impact in the liquid flow, the coating is required to have good toughness, high wear resistance, fluid corrosion resistance, and no brittleness. Available Ni-based self-fluxing alloys, copper alloys containing AI9.5%, Fe1%, copper alloys containing Ni38%, self-fluxing alloys plus Ni/Al mixed powder, 316 stainless steel, ultra-fine Al2O3 and pure C2O3, etc., and All coatings should be sealed. Specific application parts such as: turbine blades, wear rings, nozzles and diesel engine cylinder liners, etc.



(7) Erosion and wear resistant coating. These coatings are required to withstand abrasion caused by sharp hard particles. Several kinds of Ni-based self-fluxing alloy powder, self-fluxing alloy plus fine copper mixed powder, high Cr stainless steel powder, ultra-fine Al2O3 powder, pure Cr2O3 powder, Al2O3 + TiO2 13% composite powder and Co/WC composite powder can be used. Specific application parts such as: exhaust fan, water valve and cyclone dust collector.