Non-cyanide converting method for cyanide plated zinc

Abstract

The invention relates to a non-cyanide converting method for cyanide plated zinc. Non-cyanide conversion is as follows: a brightening agent (HT) and a complexing agent (HEDP) are added into plating liquid to carry out zinc plating by stopping adding NaCN and ZnO into the plating liquid. The plating liquid comprises the following components (g*L-1): 10-less than 5 of cyanide, 8-15 of zinc oxide, 60-120 of NaOH, 15-20 of HEDP and 2-3 of HT. The electroplating technical condition comprises the temperature of 10-45 DEG C, the cathode current density (A*dm<-2>) of 0.5-4 and the average current efficiency of 70-78 percent. The corrosion resistance, the bonding capability and the color change resistance of a plating layer completely meet the practical production requirement. The plating liquid has high impurity resistance and is still stable for continuously using for one month. The converted process does not use the cyanide, is easy to process electroplating wastewater and is a more clean production process, thereby replacing a cyanide zinc plating process in a peace way.

Description

technical field [0001] The invention belongs to the technical field of electrolysis or electrophoresis to produce a coating on a metal surface, and in particular relates to the electrogalvanizing technology of a zinc solution containing cyanide. Background technique [0002] The cyanide galvanizing process has been used for hundreds of years. Although it is a mature process, it also has the defect that improper management and disposal of sodium cyanide will cause great harm to human life and the living environment. The National Development and Reform Commission clearly proposed to eliminate the cyanide galvanizing process in Article 15 of the third category of elimination in the "Industrial Structure Adjustment Guidance Catalogue". Therefore, the electroplating industry is faced with the choice of directly abandoning the cyanide galvanizing process and transforming the cyanide galvanizing process. However, the cost of directly discarding the cyanide plating solution to prep...

AI Technical Summary

Problems solved by technology

However, there is a problem in the practical application of this method, that is, the CN - Complexed Pb 2+ , Fe 3+ 、Cu 2+ A large number of impurity ions are precipitated, which is difficult to remove by electrolysis, which seriously affects the quality of electroplating, and even causes the electroplating bath to be scrapped.

In addition, there are incompatibility problems between the added additives and the original additives

[0005] At present, there is no report on a cyanide-free conversion galvanizing process that is effective and can ensure good coating quality and high electrical efficiency.

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