What are the properties and application characteristics of hard sintered alloy cermet powder

       1) Cobalt tungsten carbide sintered powder



     Cobalt tungsten carbide sintered powder is a cermet material with cobalt as the binder metal and tungsten carbide as the hard particles. In the Co-WC system, the Co content is 12% to 18%. It has excellent wear resistance below 500 ℃, and is the most widely used wear-resistant material. Under the action of high temperature, part of WC will undergo decarburization and decomposition. In the spraying process, increasing the speed of particles, shortening the heating time and controlling the temperature of the flame can effectively inhibit the occurrence of decomposition.

     The combination of cobalt and WC has two types: sintered and clad. The thermal spray coating type Co-WC powder has the smallest burning loss of WC. Sintered cobalt tungsten carbide powder has fine particle size and poor fluidity, so special treatment is required. However, the price of cobalt-coated tungsten carbide is relatively high, so sintered cobalt tungsten carbide powder with a relatively low price is mostly used.

     Since the coating of tungsten carbide particles by sintered cobalt is not complete enough, tungsten oxide will be decomposed and oxidized to different degrees. In order to reduce burning loss and carbon loss, it is best to use vacuum plasma spraying, explosive spraying and supersonic flame spraying. The coating is dense, high hardness, firm bonding, and has excellent wear resistance.

     Cobalt tungsten carbide powder is used as wear-resistant material wear coating below 540℃, erosion wear, hard surface wear and fretting wear coating. Such as mud pump piston rod, polishing machine blade, flue fan blade, water turbine blade, wire drawing wheel of metal wire drawing machine, hydraulic piston rod of brick press, plastic extruder screw, corrugated paper roll, train crankshaft, high-speed train brake pads, etc. .

     2) Steel bonded cemented carbide powder

     Steel-bonded cemented carbide powder is a steel-bonded cemented carbide powder made by replacing the metal cobalt binder phase with steel powder, using TiC or WC particles as the hard phase, and sintering and crushing. Steels as binder phases include chrome-molybdenum steels, high-speed steels and austenitic stainless steels. Except for the nickel-chromium austenitic stainless steel-based steel-bonded cemented carbide that cannot be strengthened by heat treatment, the main feature of steel-bonded cemented carbide is that it can be heat treated,

     Steel-bonded cemented carbide coating, with fairly high hardness and wear resistance, but not suitable for high temperature applications. It can be processed into complex profiles by conventional processing methods with low cost. Vacuum plasma spraying and protective atmosphere plasma spraying can also be used to prepare low-cost high wear-resistant coatings.

     3) Tungsten carbide dispersion self-fluxing alloy powder

     Tungsten carbide dispersion self-fluxing alloy powder is a kind of metal made by adding a certain proportion of tungsten carbide powder to high-hardness nickel-based self-fluxing alloy, cobalt-based self-fluxing alloy and iron-based self-fluxing alloy Ceramic powder material. The application feature of this type of material is that it is suitable for spraying and melting a completely dense coating with high hardness and high wear resistance by powder flame spray melting process.

     Preventing the carbon burning of WC during the spray melting process is an important guarantee for obtaining a high-quality wear-resistant welding layer. The self-fluxing alloy welding layer containing WC disperse phase is suitable for high wear-resistant coating material under the working condition of 540℃.

     Tungsten carbide dispersion self-fluxing alloy powder can be used in protective atmosphere plasma spraying, explosive spraying or supersonic flame spraying process to obtain very dense and high wear-resistant cermet coating.

     Tungsten carbide dispersion self-fluxing alloy powder is suitable for wear-resistant conditions below 540 °C, as a spray-welding layer or a spray-coating layer that is resistant to low-stress abrasive wear, erosion wear, and hard surface wear. Examples of applications are: screw feeders for construction machinery, crusher shafts, mud pump plungers, sand mixer blades, scrapers, brick formwork, flue fan blades, dredger tines and pins, pulverizer rollers Road, tractor axle pins, etc.

     4) High temperature impact wear resistant nickel-based tungsten carbide composite powder

     This is a metal-ceramic composite powder composed of a high-temperature nickel-based alloy matrix phase and composite tungsten carbide. The selected high-temperature alloy contains high heat-resistant alloy components Co, Mo, Cr, etc. Therefore, the matrix phase of the nickel-based superalloy has high strength, good impact toughness, good cold and thermal fatigue resistance, and excellent high temperature oxidation performance.

     A high temperature impact wear resistant welding layer with metallurgical bonding is formed on the steel substrate by the plasma spray welding process. It is used for surface surfacing welding of large diameter hot-rolled seamless steel pipe hot-rolled reaming forming plug, hot-work die surfacing welding, etc. The service life of the spray-welded plug is 3 to 5 times higher than that of the original Cr17Ni2Mo heat-resistant cast steel plug, and the benefits are very prominent.