Manufacturing process of metal seated ball valve nickel-based tungsten carbide wear-proof coating

Abstract

The invention discloses a manufacturing process of a metal seated ball valve nickel-based tungsten carbide wear-proof coating. The manufacturing process includes the following steps that S1, the surfaces of workpieces are pre-treated, wherein a machined ball body and a machined valve seat are subjected to surface cleaning and coarsening; S2, a wear-proof coating is sprayed, wherein a wear-proof coating powder material is evenly sprayed to the surfaces of the ball body and the valve seat through a hypersonic flame spraying process; S3, heating and remelting are carried out, wherein the sprayedball body and the sprayed valve seat are put in a vacuum furnace in batches for heating and remelting, and the ball body and the valve seat are metallurgically bound with the wear-proof material; S4,cooling is carried out, wherein after being remelted, the ball body and the valve seat are slowly cooled along with the vacuum furnace; and S5, grinding is carried out, wherein the cooled ball body and the cooled valve seat are precisely ground in sequence through a grinding device. The strength of the wear-proof coating on the sealing face of a ball valve can be improved, then the wear-proof performance of the sealing face of the ball valve is enhanced, and the service life of the ball valve is prolonged.

Description

technical field [0001] The invention relates to the technical field of wear-resistant coatings for valves, in particular to a manufacturing process for nickel-based tungsten carbide wear-resistant coatings for metal hard-sealed ball valves. Background technique [0002] Metal hard-sealed ball valves are usually used in hard solid particle media, and the sealing surface of the ball valve is required to have good wear resistance, scratch resistance, high temperature resistance, and corrosion resistance. In order to meet the above requirements, wear-resistant materials are usually sprayed on the surface of the metal hard-sealed ball valve and the valve seat, and the following two processes are generally used: (1) Oxyacetylene flame spraying process; (2) Supersonic flame spraying process. But there are some deficiencies in these two ways. [0003] Problems encountered in the oxyacetylene flame spraying process: A. Although the nickel-based alloy wear-resistant coating melts to ...

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Problems solved by technology

[0003] Problems encountered in the oxyacetylene flame spraying process: A. Although the nickel-based alloy wear-resistant coating melts to the surface of the substrate through high-temperature heating, and achieves metallurgical bonding with the substrate material, the bonding strength is high, but the wear-resistant coating only melts to the surface of the substrate , the density of the wear-resistant coating is low, so the wear-resistant performance of the wear-resistant coating is poor, and the sealing surface is easily damaged by friction under harsh working conditions

B. Before spraying the wear-resistant material, use flame to heat the sphere or valve seat. If the heating temperature is too low, the powder of wear-resistant material cannot be firmly attached to the surface of the sphere. Wear-resistant material coating is easy to fall off

If the flame heating temperature is high, it is easy to cause oxidation of the surface material of the sphere, which seriously affects the spraying quality

C. When the flame is used to heat and remelt the wear-resistant material, because the thickness of each part of the sphere is very different, it is difficult to ensure uniform heating of each part of the sphere. Excessive heating temperature will lead to some elements in the nickel-based alloy. Burning loss, while the temperature is too low, the wear-resistant material cannot be remelted and metallurgically combined with the base material

In addition, heating with a flame in the atmosphere will also cause oxidation of the material and reduce the quality of the coating

D. The use of flame heating requires a faster heating rate. The heating process is too slow, which will lead to severe oxidation of the material at high temperature, but the heating rate is too fast, it is not easy to ensure the uniform temperature of the sphere, and it is easy to cause cracks in the material

[0004] Problems encountered by supersonic flame spraying: A. The wear-resistant material powder is sprayed onto the surface of the base material at a very high speed. Therefore, the wear-resistant material powder and the base material have a high density, but the use of supersonic flame spraying , the wear-resistant material powder is only sprayed on the surface of the substrate at high speed, without high temperature melting together, there is no metallurgical bond between the two, the bonding strength is low, and it may fall off under harsh working conditions

B. Using supersonic flame spraying, the wear-resistant coating is superimposed and sprayed onto the surface of the substrate layer by layer. Usually the thickness of the coating is small, and increasing the thickness of the coating will reduce the bonding force between the wear-resistant coating and the substrate. Therefore, using supersonic The wear-resistant coating by sonic flame spraying has a small coating thickness, which cannot fully meet the wear-resistant requirements of harsh working conditions

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