CN102234825A - Industrial method for citrate alkaline non-cyanide copper plating on steel substrate - Google Patents

Abstract

The invention discloses an industrial method for citrate alkaline non-cyanide copper plating on a steel substrate, and the industrial method comprises the following steps: evenly mixing 30g/L of copper sulphate, 147g/L of sodium citrate, 45g/L of potassium sodium tartrate, 10g/L of sodium bicarbonate, 0.2g/L of polyethylene glycol, 1.2mg/L of 2-mercapto benzothiazole, 1g/L of hg01 additive, 1mL/L of hg02 additive and 8g/L of potassium nitrate in a retort; and adjusting pH to 9.0 by sodium hydroxide; and electroplating at 45-50DEG C with the current density being 1-10A/dm<2> for 5-10 minutes to obtain the citrate alkaline non-cyanide copper-plated steel substrate. The performance of the used plating solution and a plating layer obtained with the method is excellent, and the plating layer and the substrate have good bonding force and large coverage area. The citrate alkaline non-cyanide copper-plated steel substrate is economical and environmentally-friendly and has the advantages of long use cycle and good stability.

Description

The copper-plated industrial method of Citrate trianion alkaline non-cyanide on the steel substrate

(1) technical field: the present invention relates to a kind of method of cyanide-free copper electroplating, specifically is the copper-plated industrial method of Citrate trianion alkaline non-cyanide on the steel substrate.

(2) prior art: for cyanide-free copper electroplating technology, all carried out suitable extensive studies both at home and abroad, and also developed multiple cyanide-free copper electroplating technology.These process using diversified complexing agent in the hope of solving the bonding force problem, replace the application of cyanide copper plating process in actual production, but relative merits separately all arranged.With main complexing agent is that research system mainly contains the following aspects:

(1) pyrophosphate copper plating

Pyrophosphate copper plating can not directly be plated on the matrix of iron and zinc.Current pyrophosphate copper plating has been widely used in tubulose and the complex part copper facing process for upsetting before being used for the copper facing of zinc alloy matrix plating hydrosulphate, avoids the corrosion of strong acid in order to protect matrix, guarantees the quality that coating makes up.The crystallization of light pyrophosphate copper plating is careful, has good dispersive ability and covering power, the cathode efficiency height, but its shortcoming is the cost height, the phosphoric acid salt accumulation can take place in life-time service, makes sedimentation velocity descend the waste water control difficulty.

S.S.Abd EIRehim etc. has studied and has utilized the copper facing novel process of Sunmorl N 60S as complexing agent, can obtain careful, uniform copper coating on steel substrate.This technology mainly is to be used for thickening in other copper plating grooves more subsequently at surface of steel workpiece flash one deck thin copper layer.Cu in plating bath ²⁺With C ₆H ₁₁O ₇ ^-Can form highly stable complex compound, along with the rising of pH value, the stability of complex compound is also high more, and might form highly stable huge legendary turtle cyclization, makes free Cu in the solution ²⁺Significantly reduce.Can cause Cu on the negative electrode like this ²⁺Discharge is difficulty very, and the bath voltage during plating is very high, and current efficiency is very low also.Therefore can only under lower pH value condition, electroplate.

(2) citrate copper-plating

Citric acid is the good complexing agent of copper, can form highly stable complex compound, can effectively prevent the copper displacement phenomenon on the steel part.Copper plating bath dispersive ability and covering power with the Citrate trianion preparation are good, and current efficiency is higher, and resulting coating is even, careful; Electroplating current density a wider range of plating bath.The routine maintenance of plating bath is also comparatively simple, and totally nontoxic is harmless.Because various advantages, Citrate Copper Plating Bath has obtained people's broad research, has also occurred two complexing agent copper-plating techniques in succession.Citrate copper-plating is regarded as substituting fully the ideal system of cyanide copper plating process.

(3) thanomin copper facing

S.M.Maganna etc. have studied with the decide copper-plating technique of complexing agent of trolamine.This technology can be on steel substrate directly copper facing, can obtain light, careful, uniform coating.The dispersive ability and the covering power of plating bath are better, but the cathode current density scope that is suitable for is too narrow, burns easily in high Current Zone.The bright range of test piece is also narrow, is not suitable for lining general labourer part.

(4) edta salt copper facing

People such as R.M.Krishnan have studied and have used EDTANa ₂Do the copper-plating technique of complexing agent.EDTA energy and Cu ²⁺Form sufficiently stable complex compound, make Cu ²⁺Current potential become negative, make above the iron and steel and can not produce replacement(metathesis)reaction, thereby make between steel substrate and the copper layer extraordinary bonding force is arranged.

Zhou Weiming has worked out EDTANa ₂The two complexing copper-plating techniques of-tartrate, bath stability and covering power are very good, but current efficiency is minimum, and it is a little that leveling property is compared citric acid-tartrate system difference.Generally speaking, EDTA copper facing is a kind of technology of very feasible replacement cyanide copper plating liquid, and the current density range that plating bath is suitable for is very wide, is easy to just can obtain light, uniform copper coating, but also can be used for the copper electroforming.But because the alkalescence of plating bath is stronger, tiny copper powder (Cu can appear in solution ₂The O powder), can reduce the appearance of this phenomenon, and can be implemented in than electroplating under the low pH condition by the amount that increases EDTA.But EDTA combines the effect of boiling together that forms with copper too strong, is not easy to the processing of waste water.

(5) HEDP copper facing

1-Hydroxy Ethylidene-1,1-Diphosphonic Acid (HEDP) copper plating bath system composition is simple, coordination agent stable, and is easy to operate, the current efficiency height, the covering power of the fast plating bath of sedimentation velocity is better than the prussiate system, coating crystallization light, careful, good with iron-based body bonding force, can directly apply to the preplating of iron-based.Abroad, HEDP copper facing has been used for producing in enormous quantities report.The cyanide-free alkaline copper plating of producing Plaschem and Cupral all adopts organic phosphonate as part.Domestic just have a how tame factory application copper-plating technique in the 1980s, production practice find that this technology has the current density can not be big, coating can not be too thick, easily produce copper powder, iron contamination in the plating bath is more difficult, and the HEDP copper plating solution is owing to contain a large amount of phosphorus in the plating bath, and its sewage disposal is the difficulty of ten minutes also.For these reasons, this system fails to be used widely.

(6) other copper-plating technique

Barbosa.L. wait the people to study and utilize the copper plating bath of Sorbitol Powder, and the crystalline state and the granular size of coating surface are analyzed with microscopic approaches such as SEM as complexing agent.Because Sorbitol Powder and Cu ²⁺The complex compound stability that forms is very strong, can copper and zinc common deposited be come out the negative current potential that moves on near zinc of the current potential of copper.Carlos etc. utilize the brass-plating technology of Sorbitol Powder as complexing agent, and the ratio of copper in the solution and zinc has been carried out analyzing in detail, and detailed discussion has also been done in consequent influence to coating.

The problem that cyanide-free alkaline copper plating research exists:

By retrieval both domestic and external, people were less to the research report of cyanide-free alkaline copper plating in recent years.Excellent processing condition are also in constantly testing.The problem that exists in technical study has:

1) bonding force. at present, developed multiple cyanide-free copper electroplating technology both at home and abroad.The problem of ubiquity copper facing bonding force difference on steel substrate.Mainly be subjected to the passivation of replacement(metathesis)reaction, iron-based body, three kinds of factor affecting of deposition of matrix surface.Replacement coating is meant the metal ion that deposition potential is very positive, as Ag ⁺, Cu ²⁺Deng, in plating bath, be easy to by the negative matrix metal of deposition potential such as iron, zinc displacement, and on matrix, form one deck coating loose, that bonding force is not strong.Want not produce serious displacement copper and directly galvanic deposit, can only adopt complex compound to electroplate.When metallic matrix is exposed in air or the solution, the surface forms the very thin zone of oxidation of one deck easily.The method that Feng Shaobin utilizes argon ion sputtering and x-ray photoelectron power spectrum to combine detects, and finds that the existence of copper coating and iron-based body bottom boundary oxygenous layer is the major cause that influences coat binding strength.This requires to carry out the strict more advanced technology of handling or use before plating.The most key is deposition process how to improve matrix surface.It comprises factors such as metal refining grain size, metallic surface state.Existing processing mode still influences metal electrodeposition process by attempting additive.The additive that has stops the crystallization of copper in deposition process, play the effect of crystal grain thinning; The additive that has plays wetting action to the metallic surface, helps metallic surface " cleaning " improved surface effect.

2) plating solution performance. as prime coat, plating bath should have the use current density of good dispersive ability, leveling ability, covering power and broad, and these spare and accessory parts that could satisfy different size use.And in order to satisfy suitability for industrialized production, the stability of plating bath (comprise that anode does not produce that copper powder, plating bath life cycle are long, plating bath is subjected to that impurity effect is little, plating bath bubble or the like not) is also most important, the requirement that this helps economic environmental protection and recycles.

3) coating performance. the alkaline copper plating layer only needs half light, and often people pursue light simply to the selection of additive, and this is wrong guiding.The problem that copper plate also often occurs is that fragility is big, and thickness is little, even Chromatic color or the like.These all are the problems of avoiding in the technical study.

4) plating bath viscosity height during industrialization, technology is difficult for operation and maintenance, is difficult to thoroughly solve the problem of matrix and copper coating bonding force.

(3) summary of the invention: purpose of the present invention just provides a kind of plating bath and coating performance excellence, between coating and matrix good bonding force is arranged, area coverage is big, economic environmental protection, life cycle is long, the copper-plated industrial method of Citrate trianion alkaline non-cyanide on the steel substrate of good stability.

The inventive method is as follows:

Get copper sulfate 30g/L, Trisodium Citrate 147g/L, Seignette salt 45g/L, sodium bicarbonate 10g/L, polyoxyethylene glycol 0.2g/L, 2-thin basic benzothiazole 1.2mg/L, hg01 additive 1g/L, hg02 additive 1mL/L, saltpetre 8g/L, place retort to mix, transfer pH=9.0 with sodium hydroxide, at temperature 45-50 ℃, current density 1-10A/dm ²Condition under electroplate 5-10 minute promptly.

The relevant plating bath and the coating performance excellence that show this method after testing can satisfy the requirement of bottoming or plating intermediate gauge.On the product adaptation iron-based body after the plating directly the plating end copper needs, coating has half light, thickness can reach 2-8 μ m (intermediate deposit), and and matrix between good bonding force is arranged; The dispersed T=73.6% of plating bath, area coverage 100%, leveling ability is good, satisfies the characteristics of economic environmental protection, life cycle length, good stability.

Citrate bi complex system alkaline copper plating technology of the present invention can replace cyanide copper plating technology fully, fundamentally solves the severe contamination of cyanide copper plating to environment, improves labor's Working environment greatly.The suitability for industrialized production of citrate bi complex system alkaline copper plating technology can promote the cyanide-free copper electroplating industrial expansion, and environment protection is played a positive role.

(4) embodiment:

Embodiment 1

Get copper sulfate 30g/L, Trisodium Citrate 147g/L, Seignette salt 45g/L, sodium bicarbonate 10g/L, polyoxyethylene glycol 0.2g/L, 2-thin basic benzothiazole 1.2mg/L, hg01 additive 1g/L, hg02 additive 1mL/L, saltpetre 8g/L, place retort to mix, transfer pH=9.0 with sodium hydroxide, at temperature 45-50 ℃, current density 1-10A/dm ²Condition under electroplate 5-10 minute promptly.

Claims (1)

1. the copper-plated industrial method of Citrate trianion alkaline non-cyanide on the steel substrate, it is characterized in that: get copper sulfate 30g/L, Trisodium Citrate 147g/L, Seignette salt 45g/L, sodium bicarbonate 10g/L, polyoxyethylene glycol 0.2g/L, 2-thin basic benzothiazole 1.2mg/L, hg01 additive 1g/L, hg02 additive 1mL/L, saltpetre 8g/L, place retort to mix, transfer pH=9.0 with sodium hydroxide, at temperature 45-50 ℃, electroplate 5-10 minute under the condition of current density 1-10A/dm2 promptly.