Method for spraying Stellite 20 alloy on surface of workpiece

Abstract

The invention relates to a method for spraying a Stellite 20 alloy on the surface of a workpiece. The method comprises the following steps that (1), surface treatment is conducted, specifically, the size of a machined workpiece is detected, cleaning is conducted, and sand blasting and roughening are conducted on the surface of the workpiece, so that the roughness Ra of the surface of the workpiece is 10 microns-13 microns; and (2), the surface of the sprayed workpiece is preheated to 70 DEG C-90 DEG C, spraying equipment is adopted for spraying Stellite 20 alloy powder to the surface of the workpiece, and a coating is deposited for multiple times to make the thickness of the coating be 0.25 nm-0.35 mm. By the adoption of the method, the thickness of the coating on the surface of the workpiece is uniform, the binding force between the coating and a base body is good, the porosity of the coating is low, oxide inclusions are few, the abrasion resistance and corrosion resistance of the coating are good, and the technical indexes required by the valve application field can be met, wherein the hardness is larger than or equal to 750 HV0.3, the porosity is smaller than or equal to 1%, the binding force is larger than or equal to 70 MPa, and the oxide content is smaller than or equal to 2%.

Description

technical field [0001] The invention belongs to the field of spraying, in particular to a method for spraying Stellite 20 alloy on the surface of a workpiece. Background technique [0002] Stellite alloy is a hard alloy with excellent friction and wear resistance, acid and alkali corrosion resistance, and high temperature oxidation resistance. It has made important contributions to the development of aerospace, automobile, metallurgy, high temperature chemical industry and other industries. There are more than 30 grades of Stellite alloy, and the commonly used grades are Stellite 1, Stellite 6, Stellite 12, Stellite 20 and Stellite 21, etc. In addition to being made into castings, Stellite alloys are often used to make small parts such as molds, blades, nozzles, etc., while large parts are prepared by thermal spraying technology to prepare Stellite coatings on the working surface to save expensive manufacturing costs. [0003] Hypersonic Oxygen Spraying (HVOF) technology i...

AI Technical Summary

Problems solved by technology

[0005] However, at present, the Stellite 20 alloy coating prepared by most spraying factories through the supersonic flame spraying technology has a high porosity of the coating as measured by the metallographic examination, usually reaching about 3%, which is far lower than the technical index required in the valve application field ( ≤1%), greatly reducing its wear resistance and corrosion resistance

In addition, due to the insufficient control of the pre-processing size of the workpiece and the details of the spraying process, uneven coating thickness, oxide inclusions, and internal stress concentration of the coating reduce the bonding strength between the coating and the substrate.

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