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Preventing wear of fan impellers and protective measures for abrasives

The wear of the fan impeller is related to the composition, particle size, concentration, shape, impact velocity, impact angle, chemical composition, properties, temperature and humidity of the abrasive. The unevenness of the gas flow inside the impeller accelerates wear. As measures to prevent impeller wear: First, reduce dust and corrosive gases entering the fan, for which it is necessary to modify the fan operating system; second, try to make local wear tend to wear evenly, which requires improving the wear resistance of the impeller. . If the wear resistance of the impeller is improved, a material having high hardness and wear resistance can be used. Not only does this create difficulties for the impeller manufacturing process, but it is also unreasonable from an economic point of view. Therefore, it is an economical and reasonable solution to improve the surface quality of the fan impeller, and to weld the wear-resistant layer of the impeller wear or spray-weld (spray) wear layer and add a layer of lining on the blade to achieve wear resistance.

Coated wear resistant coating

The main anti-wear coatings are resin anti-corrosion and wear-resistant coatings, rubber anti-corrosion and anti-wear coatings, quartz water-added glass and ceramic anti-corrosion and wear-resistant materials.

The 890 wear resistant compound is a ceramic composite used to repair and protect the surface of the abraded metal. The wear resistance of the compound and the adhesion to the base material are both good. However, the coating thickness of the 890 wear-resistant compound must be 6mm or thicker, which is not suitable for some narrow runners or rotors with strict start requirements. Similarly, a wear-resistant liner is added to the blade to solve the fan. There are also such problems with impeller wear.

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Blade surface surfacing

Surface surfacing is the selection of a certain surfacing electrode (or welding wire), manual arc (or automatic welding) surfacing in the wearable parts of the blade to improve the surface quality of the blade to protect the blade and improve blade life. Blade surfacing welding rods generally use D217, D237, D317B, D707 and D717, etc. D217 and D237 surfacing metals belong to horse body steel, which has certain anti-wear ability, but the surfacing crack tends to be larger. D317B surfacing material is a kind of surfacing alloy composed of a large amount of tungsten carbide (WC) particles distributed on the metal substrate. Because of the high melting point and hardness of WC, the hardness of the weld bead metal is also high and impact resistance, hardness HRC≥ 60, the phenomenon of weld metal cracking tends to be small.

Surface spray welding (spraying)

The spray welding process is a process in which a self-fluxing alloy powder is sprayed and melted on a surface of a workpiece by a heat source to form a dense spray-welded layer. Each of the spray-welded wear-resistant powders is basically a nickel-based spray-welded powder of the Ni-Cr-B-Si series. The basic structure of their spray-welding layer is a solid solution of Ni-Cr-Fe, and there are a large amount of boron compounds and tungsten carbide. These WC particles are evenly distributed in the Ni-based spray layer. These particles are uniform and discontinuous, but can be formed. A skeleton with a hardness of HRC70. The Ni-based material is filled in the skeleton and can withstand the wear of highly abrasive particles when subjected to abrasive scouring. The surface hardness of the spray welding surface is HRC 55-70, and its basic composition is Ni60%+WC35%.

Precision casting