Method for densifying electroplating hard chromium layer

Abstract

The invention relates to a method for densifying the surface of an electroplating hard chromium layer, which comprises the following steps: the electroplating hard chromium layer of a metal matrix is treated and cured in advance according to the conventional technology, then the electroplating hard chromium layer of a metal component is performed an impact treatment by a bullet with a certain specification, a certain impact intensity, a certain impact angle and coverage rate, so that the surface of the electroplating hard chromium layer can be densified and the crack gap is decreased, and theelectroplating hard chromium layer is in a no tension stress state, the phenomena of matrix corroding, spalling or cracking caused by the defects of the structure of electroplating hard chromium layer can be substantially improved.

Description

technical field [0001] The invention relates to a method for densifying an electroplated hard chrome layer, which is particularly suitable for obtaining better protection ability after electrodeposition of a hard chrome layer on a metal substrate, and makes the substrate not affected by the stress of the plating layer, and belongs to the technical field of special metal processing . Background technique [0002] The electroplating hard chrome coating has the advantages of high hardness (generally HV700-1000) and relatively good wear resistance, and can maintain a bright surface for a long time in the air, and the process is relatively simple, which can provide coating for the outer surface of complex workpieces. layer, and can provide a wear-resistant coating for the inner cavity of the workpiece, while the processing cost is low. Improving the surface hardness of workpieces by electroplating hard chromium is one of the most economical methods in surface engineering. Electr...

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Problems solved by technology

[0003] However, the electroplated hard chrome coating has a large tensile stress, which causes microcracks in the electrodeposited coating, and cracks exist from the initial formation of the deposited layer. Therefore, as the thickness of the coating increases, there will inevitably be penetration inside the coating. (1) lead to the slow decrease of hydraulic pressure or air pressure in the sealed cavity that needs to be maintained at high pressure, thus making it difficult to guarantee the sealing performance, and the phenomenon commonly known as "sweating" occurs; (2) leads to the need for anti-corrosion protection Premature corrosion of steel, copper alloy and aluminum alloy substrates; (3) lead to damage or peeling of the coating during sliding or rolling friction; (4) for shaft parts, as the thickness of the coating increases, the tensile stress inside the coating also corresponds Increase, the width and length of cracks on the surface of the coating will increase, these micro-cracks and the tensile stress of the coating will become the source of cracks in the metal matrix, resulting in cracks in the metal matrix of shaft parts, which will lead to failure of the parts in severe cases

Although there are many methods to improve the electroplating hard chromium layer, such as coating grinding and pressing, liquid sealing, etc., the above phenomenon has not been eradicated.