Preparation method of cobalt-based anti-cavitation coating of plastic deposition based on work hardening

Abstract

A preparation method of a cobalt-based anti-cavitation coating of plastic deposition based on work hardening comprises the steps that an oxidization film on the surface of a metal matrix is removed, oil dirt and residual impurities on the surface are removed through cleaning, and after the metal matrix is dried in air, the matrix is fixed to a workbench; (2) powder is placed in a vacuum drying boxto be dried, and after being dried, the powder is cooled to room temperature to be placed in a powder feeder; (3) the carrier gas kind, the carrier gas pressure, the preheating temperature and the powder feeding rotating speed are set in a cold spraying panel; (4) laser power is set in a laser control panel; (5) a mechanical arm is started, the spraying coating lap-joint rate and the scanning speed are input, the mechanical arm is adjusted, so that a cold spraying nozzle is perpendicular to the surface of the matrix, and the angle of a laser head is adjusted, so that laser spots coincide withspraying powder spots; (6) equipment is started, and supersonic-speed laser deposition experimenting is carried out in the matrix; and (7) after processing is completed, the coating on the surface ofthe metal matrix is subjected to aftertreatment, and the surface of the coating is leveled.

Description

technical field [0001] The invention belongs to the field of material surface modification, and in particular relates to a preparation method of a cobalt-based anti-cavitation coating based on work-hardening plastic deposition. Background technique [0002] As the core component that converts air kinetic energy into useful work, steam turbine blades play a very important role in the entire steam turbine system. However, during the long-term service of the steam turbine, the blades of the steam turbine, especially the low-pressure last-stage blades, are in a humid steam environment for a long time. When the liquid flows, due to the sudden drop in pressure, the liquid will vaporize, and the bubbles will collapse under the pressure. Shock waves and micro jets continuously impact the blades, breaking the surface material, causing cavitation damage on the top of the steam inlet side and the root of the steam outlet side. Cavitation is a hidden and dangerous phenomenon of hydrody...

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Problems solved by technology

[0003] At present, for the problem of blade cavitation, the most widely used protective measure is to braze the Stellite alloy sheet at the edge end area of ​​the inlet side of the last stage blade, but this method has unstable brazing quality, and the welding layer does not match the blade shape. Good, the alloy sheet and the substrate are not firmly bonded (non-metallurgical bond) and easy to fall off, etc.

In recent years, surface modification technology has also been used to strengthen steam turbine blades, such as using laser cladding, surfacing and other technologies to coat a layer of protective coating on the metal surface, but due to the large heat input of these technologies, the prepared coating has Oxidation, phase change, thermally induced residual stress, grain growth, high dilution rate and other adverse problems, so the cavitation resistance of the prepared coating is still not very high

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