Research On The Non-cyanide Electroplating Copper-zinc Binary Alloy Technology

In the history of electroplating Cu-Zn alloy for nearly one hundred years,the developed Cu-Zn alloy plating solution is more stable than the cyanide plating solution.However,because cyanide is highly toxic,it is potentially harmful to the human body and the environment.At the same time,with the vigorous development of clean production in China,the cyanide plating solution will fade out of the historical stage.At present,relevant government departments have promulgated a series of relevant regulations,requiring the development of non-cyanide electroplating to gradually replace cyanide plating.Therefore,it is to develop a cyanide-free electroplating Cu-Zn alloy process which is stable and has excellent plating color,which meets environmental protection requirements and meets the needs of clean production in the electroplating industry.In this paper,the basic formulation of Cu-Zn alloy without cyanide plating is first studied,Comparison of glycerol-zincate system,pyropHospHate system,HEDP system,tartrate system,ethylenediaminesystem,combinedwithpreviousresearchresults,comprehensive environmental protection,safety,economic benefits,stability effects,etc.The system is more suitable.The optimal ratio and optimum amount of copper ion and zinc ion were investigated by Hall cell experiment,and the suitable auxiliary complexing agent and conductive salt were screened by single factor experiment.The basic formula of the system was determined by orthogonal experiment.The electrolyte composition was determined as:copper sulfate 30g/L,zinc sulfate9g/L,potassium tartrate sodium 90g/L,potassium oxalate 35g/L,lactic acid 15g/L,carbonic acid potassium 20g/L.Through single factor experiments,various process parameters were explored by using current density range,current efficiency,copper content of coating,appearance and microscopic morpHology as evaluation indexes.The process conditions were determined to be:pH12.2-12.8,temperature 35-45?,current density range 3-4 A/dm~2,plating time 2-8 min.Secondly,the basic formula of the system was optimized,and the effects of brighteners and surfactants on the gloss of the coating were studied by single factor experiments.The results showed thatseleniumdioxide,2-sulfenylbenzimidazole,benzotriazole,sodiumdodecylbenzenesulfonate,sodium lauryl sulfate,OP-10,Tween 80 Significant effect on coating gloss.Selecting selenium dioxide,2-sulfenylbenzimidazole,sodium dodecylbenzenesulfonate and Tween 80 as additives,and then using the orthogonal test to optimize the selected brightener and surfactant.The compound additive process means that the amount of each component is 8 mg/L of selenium dioxide,1.5 mg/L of2-mercaptobenzimidazole,90 mg/L of sodium dodecylbenzenesulfonate,and 50 mg/L of Tween80.Through experiments,it is found that the optimized formula has good bonding force,the coating is bright and the crystal is fine,and has good depth ability and dispersing ability.Finally,the performance of the plating solution and coating of the system is comprehensively tested.Tests including bonding strength,hardness,corrosion resistance,dispersibility,depth capability and porosity.The results showed that copper sulfate 30g/L,zinc sulfate 9g/L,potassium sodium tartrate 90g/L,potassium oxalate 35g/L,lactic acid 15g/L,potassium carbonate 20g/L,selenium dioxide 8mg/L,2-mercapto Benzimidazole 1.5mg/L,sodium dodecylbenzenesulfonate 90mg/L,Tween 80 50mg/L,at pH 12.2-12.8,temperature 35-45?,current density range 3-4A/dm~2,Under the condition of electroplating time of 2-8min,the bonding strength of the coating is good,the hardness is slightly improved,the porosity is less than 1/cm~2,the dispersing ability and depth are better,and it is obviously better than the plating layer of the basic plating solution.The microstructure was analyzed:the obtained coating was fine and smooth.This system can obtain a stable gold-colored Cu-Zn alloy coating(copper content 68%-75%).