Acid cyanide-free electrogalvanizing technique with LHE (low-hydrogen embrittlement)

Abstract

The invention discloses an acid cyanide-free electrogalvanizing technique with LHE (low-hydrogen embrittlement). The technique comprises the following steps: step 1, pre-plating treatment: dirt and impurities on the surface of a to-be-plated piece are removed, and the surface of the to-be-plated piece is activated; step 2, plating: the to-be-plated piece is placed in a cyanide-free electrogalvanizing solution for electroplating, wherein the cyanide-free electrogalvanizing solution contains 65-75 g / L zinc, 180-220 g / L potassium and 25-30 g / L boric acid, has PH of 5.0-5.5, temperature of 20-35 DEG C and current density of 1-3 A / dm<2>; step 3, post-plating treatment: passivation treatment and aging treatment are included.

Description

technical field [0001] The invention relates to an electroplating method, in particular to a galvanizing process. Background technique [0002] Although the cyanide galvanizing process that is still widely used has the advantages of stable plating solution, high cathodic polarizability, strong throwing and deep plating ability, etc., cyanide is a highly toxic and dangerous chemical, which is harmful to operators and the environment. A certain degree of harmfulness; and the cyanide-containing wastewater must be professionally treated by the sewage treatment station, and can only be discharged after reaching the standard; the comprehensive cyanide galvanizing is from the preparation of the plating solution, galvanizing production to the recycling of the plating solution and wastewater treatment in the later stage. There are safety and environmental risks. The National Development and Reform Commission’s No. 40 "Industrial Structure Adjustment Guidance Catalog (2005)" Article 1...

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Problems solved by technology

[0002] Although the cyanide galvanizing process that is still widely used has the advantages of stable plating solution, high cathodic polarizability, strong throwing and deep plating ability, etc., cyanide is a highly toxic and dangerous chemical, which is harmful to operators and the environment. A certain degree of harmfulness; and the cyanide-containing wastewater must be professionally treated by the sewage treatment station, and can only be discharged after reaching the standard; the comprehensive cyanide galvanizing is from the preparation of the plating solution, galvanizing production to the recycling of the plating solution and wastewater treatment in the later stage. There are safety and environmental risks. The National Development and Reform Commission’s No. 40 "Industrial Structure Adjustment Guidance Catalog (2005)" Article 15 of the third category of elimination category clearly requires the elimination of cyanide galvanizing process. Aerospace standards have also included The cyanide galvanizing process is included in the "Catalogue of Prohibited (Restricted) Processes for Aerospace Products". Affecting the progress of batch product production tasks, therefore, carrying out research on new cyanide-free electro-galvanizing technology and replacing highly toxic cyanide electro-galvanizing technology is the only way to reduce safety production risks, reduce environmental pollution, enhance industry competitiveness, and promote the harmonious development of enterprises

[0003] The cyanide-free electro-galvanizing process technology has been screened like a big wave and continuously improved in practice. Two main cyanide-free galvanizing processes, acid potassium chloride galvanizing and alkaline zincate galvanizing, have been established, and have been used in long-term actual production. It has achieved considerable development, and the quality of the coating is close to that of cyanide galvanizing, which can basically meet the requirements of most galvanized products, but there are still unstable plating solutions, poor throwing ability, high brittleness and poor bonding force of the coating. And other defects, when the thickness of the coating exceeds a certain range, the brittleness increases, and there are certain risks in actual production and use. Therefore, it is currently less used in the aerospace field, especially in the electroplating treatment of precision instrument parts.

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