Sunday, April 23, 2017

Metal seated ball valve HVOF technology (HVOF)

Metal seated ball valve HVOF (HVOF) mainly through a high speed abrasion resistant powder coating material is sprayed onto the substrate surface, air velocity spraying largely determines the quality of spraying, the gun can produce more high flow velocity, the wear-resistant powder coating can achieve higher velocity, so wear powder coating and the substrate material can be obtained higher binding strength and higher density, therefore better wear resistance and corrosion resistance.

Advantages of Metal seated ball valve supersonic spray coating can be sprayed superhard materials, coating hardness can even reach HRC74 or more, so the coating has good resistance to abrasion and wear resistance properties. Further, when the supersonic spraying, the substrate material is heated to high temperatures is not required, therefore the matrix material is not thermally deformed. Because physical seal valve HVOF mainly through high-speed impact wear powder coating and the substrate material to produce a combination of bonding strength than the thermal sprayed nickel-based alloys are lower, usually combined force of about 68 ~ 76MPa, therefore For high-pressure metal seated ball valve (eg CLASS1500 ~ CLASS2500 the ball) ball, using supersonic spray coating has come off its technology may be in use.

For metal seated ball valve HVOF (HVOF), coating performance indicators are mainly the following aspects: porosity, oxide content, the hardness, bonding strength, metallurgical structure, the coating stress conditions, the coating processability, coating uniformity.

Common metal seated ball valve HVOF materials: tungsten, cobalt, tungsten, cobalt-chromium, nickel-based alloys, chromium carbide, ceramics. Tungsten, cobalt and tungsten carbide cobalt chrome temperature generally does not exceed 540 , to be applied to a higher temperature, typically sprayed chromium carbide and ceramic materials may be used.

Taking into account the binding force of a supersonic metal seated ball valve sprayed and spraying costs, the thickness of the coating layer is generally controlled at about 0.3mm, in order to ensure uniformity of the coating, the roundness of the ball before spraying and spray uniformity is very important, general the need to ensure the roundness by grinding balls before spraying, using computer-controlled robot to gun control to ensure uniformity of the coating, and the use of artificial methods to control the gun is difficult to ensure uniformity of the coating.

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Zhejiang Relia Valve Co., Ltd.
Sanqiao Ind. Zone, Oubei Town
Wenzhou, Zhejiang, 325105

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1 comment:

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