CN103510130B - Trivalent hard chromium electro-plating method - Google Patents
Trivalent hard chromium electro-plating method Download PDFInfo
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- CN103510130B CN103510130B CN201210210952.7A CN201210210952A CN103510130B CN 103510130 B CN103510130 B CN 103510130B CN 201210210952 A CN201210210952 A CN 201210210952A CN 103510130 B CN103510130 B CN 103510130B
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Abstract
The invention discloses a kind of electro-plating method electroplating Trivalent hard chromium coating on iron and steel.Use DSA anode and sulfuric acid system trivalent chromium solutions, the temperature of about 50 DEG C and the electric current density of 35～65 amperes/square decimeter, by electroplating process controlling electric current and the soft start technique of groove buckling and maintaining acidity in the range of specifying (pH0.9～2.1), obtain the trivalent chromium coating of more than 80 microns thickness, coating hardness reaches more than HV870, current efficiency is more than 35%, plating rate is the highest can reach 2 [mu, binding force of cladding material passes through thermal shock test (200 DEG C of heating, salt water quick cooling).The invention provides Trivalent hard chromium plating and replace the Cr VI hard chrome electroplating technique method of serious environment pollution, and solve existing trivalent chromium plating technology and cannot obtain the problems such as thickness coating and coating is poor with substrate caking power.
Description
Present disclosure relates to the trivalent chromium sulfate chromed hardened Technology of electricity as main salt
Technical background
Cr VI chromium plating is one of most widely used plating in electroplating industry, has a large capacity and a wide range, and iron and steel, aluminum, plastics, copper alloy and zinc-base close
On gold die casting will decorative chromium plating, the electroplating parts of function plating (hard chrome) includes hydraulic cylinder and plunger, bent axle, printed panel/cylinder, interior
Combustion engine piston, mould of plastics and the manufacture of glass fibre workpiece, cutting element etc., be also used for repair abrasion workpiece, such as cylinder, mould,
Cylinder and the reparation of bent axle.Cr VI coating has good hardness, wearability, decay resistance and dicoration, is applied not only to decorative coating,
And it is largely used to the reparation etc. of functional coating and workpiece, it is possible to utilize micro-crack layers of chrome as lubrication coating application (hard chrome) traditional chromium plating
Technology has been used up Cr VI (chromic acid) as main plating raw material, Cr VI coating, Bai Liang, hardness height, wear-resistant and Corrosion Protection
Good, and technique is simple, easy to maintenance.But sexavalence chromium plating is the most serious, one of polluter of the most intractable electroplating industry.Chromium is biological
One of necessary element of normal metabolic process, it is chaotic that scarce chromium will result in the metabolism such as sugar, fat, but chromium too high levels, then to biological and people
Health cause serious harm.Environmental Protection Agency USA (EPA) is one of toxicant being defined as 17 kinds of highly dangerous by Cr VI.Chromium is in water
Existing with trivalent and hexavalent form, the most chromic toxicity is very big, the most chromic 100 times, if chromic content is more than 0.1 in water
The concentration of mg/litre, will produce toxic action to human body.Cr VI has serious zest to skin, can cause skin ulcer, take in for a long time
The diseases such as squamous cell carcinoma, sarcoma and adenocarcinoma can be caused.Chromic waste water, refuse can not at nature natural degradation as cyanide, it
Biological and accumulated in creatures, it is possible to cause the harm of chronicity, is the extremely strong strong carcinogen of a kind of toxicity, is also serious corrosive medium and weight
Pollute the material of environment.China each department have a substantial amounts of hexavalent chromium plating tank liquor, and total amount is estimated more than ten million ton, the water of severe contamination China,
Soil and atmospheric environment, in the annual expense for administering electroplating wastewater, 60% is above for processing chromyl waste water, waste gas and refuse, and six
Valency chromium electroplates the Environmental Pollution Loss caused, and waste water processing cost and personnel's occupational disease are saved your breath also more than tens billion of RMB.
In order to replace the Cr VI chromium plating of severe contamination, people have carried out much research, including low concentration chromium plating, nickel-base alloy coating and trivalent chromium electricity
The researchs such as plating, wherein active with trivalent chromium plating and be hopeful most.
The chromium coating white color that trivalent chromium chrome plating obtains is bright, and hardness is the highest and good mechanical performance, and its dispersive property and covering power are the most far away
Higher than Cr VI, in the case of same electric current density, its deposition velocity is the twice of Cr VI chromium plating, and current efficiency is also above Cr VI.But,
The topmost advantage of trivalent chromium chrome plating is that its toxicity only has chromic 1/100th, the content of trivalent chromic ion in general trivalent chromium chrome plating solution
Only 1/7th of hexavalent chromium even less in Cr VI chromium plating tank liquor, and waste water is easily handled, it is a kind of to replace being widely used but serious
Pollute one of the most promising electroplating technology of Cr VI chromium plating of environment.But, trivalent chromium plating there is also some problems, mainly due to
Its impurity tolerance is the lowest, such as when the metal ion such as zinc, copper and mickel cumulative concentration in trivalent chromium coating bath reaches 10～100ppm, and chromium plating
Layer quality will decline, thus cause its stability bad, it is difficult to puts into production application.The hexavalent chromium produced at anode also can be serious
Affect the quality of coating, so that qualified product cannot be produced completely.The trivalent chromium bath sold on open market, it is impossible to plating thick chromium layer, at tank liquor
The aspect such as stable and maintenance there is bigger problem.Various aspects of performance can substitute the trivalent chromium plating Technology of hexavalent chromium plating also not to be had
See report.To this end, the trivalent chromium plating technology of the thickness coating that developmental research is stable (namely hard chromium) has great importance.
Summary of the invention
The invention provides a kind of stable trivalent chromium plating technology that can produce thickness coating (namely hard chrome), including solution preparation and hard chromium coating
Electroplating Process Control Techniques.Cathode-current density is more than 30%, and coating hardness reaches 870HV, 1058HV after heat treatment, and Deposit appearance is the brightest
Zero defect, neutral salt spray does not corrodes for 240 hours, 300 DEG C of thermal shock tests, without cracking.
The invention provides a kind of trivalent chromium sulfate hard chrome electroplating solution and compound method thereof, mainly include the main salt of trivalent chromium, chelating agent, buffer agent, urge
Agent composition.
The main salt of trivalent chromium plating solution is chromic sulfate or chromic potassium sulfate, and the content of trivalent chromic ion is 5～40g/L,
Chelating agent is nitrilotriacetic acid, oxalic acid, malic acid, glycine, formic acid, acetic acid or its sodium salt potassium salt, prepares plating solution, at least uses one of which complexation
Agent.Content is 1～60g/L,
Buffer agent is boric acid, aluminum sulfate, phthalic acid, prepares plating solution, at least uses one of which buffer agent, and content is 50～180g/L,
Catalyst is potassium bromide, potassium chloride, ammonium fluoride, potassium fluoride and sodium fluoride, and preparation plating solution at least uses one of which catalyst 10～30g/,
Conducting salt is potassium sulfate or sodium sulfate is 0～80g/L.Remaining is deionized water.
The pH value of described solution is 0.6～2.1, can adjust acidity, preferably 0.8～1.8 with sodium carbonate or potassium carbonate and sulphuric acid.
Compound method: first the deionized water of metering 2/3rds is put into container and is heated to more than 60 DEG C, main salt is put into deionized water while stirring
In, then it is sequentially placed into chelating agent, catalyst and buffer agent, after all dissolving, retains stand-by.Will less than metering 1/3rd go from
Sub-water is put into other container and is heated to more than 60 DEG C, is put into by buffer agent in the deionized water of this container while stirring, after all dissolving,
Pour the solution in second container into first container, be heated to about 95 DEG C, be incubated more than 2 hours, when temperature Temperature fall is to process warm
Degree, trivalent chromium bath has been prepared.
Electroplating parameter control method:
The current density range of described solution hard chrome is 25～75A/dm2' electric current density is preferably controlled in 35～60A/dm2.Electric current density is the least, does not reaches
The deposition potential of chromium；Too big, coating stress is big, easy peeling.
In the range of 0.8-2.1, along with pH value raises, current range expands, and electroplating efficiency is higher simultaneously；PH value rises, and solution activity function is inadequate,
Easily there is peeling in coating, is not suitable for electroplating for a long time；Span of control: pH value controls between 1.2～1.6 preferable.
The temperature of electroplating solution controls: temperature is low, and covering power is good, and deposition velocity is fast, but temperature is too low, and mass transfer velocity is relatively slow, long-term continuous electroplating
High-end easily burn peeling；When temperature is higher, higher electric current density can be used, but the covering power of plating solution and deposition velocity decline；Described
The temperature range of solution is room temperature～60 DEG C, and the preferred range of hard chrome plating is 45～55 DEG C, and more preferably temperature range is 40～50 DEG C.
When using described solution to electroplate, it is necessary to carry out the pre-treatment of degreasing and rust removal and activation.
Plating startup method: in order to ensure that coating and substrate have good adhesion, it is necessary to use soft-start method to electroplate.Of the present invention soft open
Moving and be meant that in 1 minute to 5 minute, the electric current density of applying is stepped up the electric current density specified from 0 ampere started.Or from
0 volt of first electroplating voltage, in 1 minute to 5 minute, progressively pressure regulation, under the voltage specified, carries out plating.
Cannot use movable cathode and solution forced flow:
In order to ensure that coating and base metal have good adhesion, in electroplating process, electroplating cathode (namely plating workpiece) is immovable, and solution is not
Circulating filtration, mechanical agitation etc. can be used to cause the additive method of solution forced flow.
Anode uses iridium tantalum coating Ti-alloy anode.
Performance test data, cathode-current density more than 30%, coating hardness 870HV, 1058HV after heat treatment, the white bright zero defect of Deposit appearance, in
Property salt fog within 240 hours, do not corrode, 300 degree of thermal shock tests, without cracking.
Power supply can also use the pulse power with DC source, and faster, the sedimentary surface of the pulse power is finer and closely woven for the deposition velocity of DC source.
Embodiment 1 solution is prepared
Use chromic potassium sulfate 230g/L, buffer agent 120g/L, chelating agent 30g/L, catalyst 20g/L, conducting salt 50g/L, press
Solution is prepared according to following method.
First the deionized water of metering 2/3rds is put into container and is heated to more than 60 DEG C, main salt is put in deionized water while stirring,
Then it is sequentially placed into chelating agent, catalyst and buffer agent, after all dissolving, retains stand-by；.Will be less than the deionized water of metering 1/3rd
Put into other container and be heated to more than 60 DEG C, buffer agent being put into while stirring in the deionized water of this container, after all dissolving, by
Solution in two containers pours first container into, is heated to about 95 DEG C, is incubated more than 2 hours, when temperature Temperature fall is to technological temperature,
Using deionized water constant volume, trivalent chromium bath has been prepared.
No. 45 steel shaft-like parts of embodiment 2 base material (the long 200mm of diameter 30*)
Hanger on mechanical polishing pre-chemical degreasing 10min-, installs screen bis-water of anode electrolysis defat 5min
Wash bis-washing pure water of activation 1min and wash plating hard chrome (directly initiating the electric current density specified)
Secondary washing pure water is washed and is unloaded hanger
Trivalent chromium coating peeling comes off.
Embodiment 3 base material 65Mn steel shaft-like part (the long 200mm of diameter 30*, wherein 50mm length in the middle of parcel plating)
Hanger on mechanical polishing pre-chemical degreasing 10min-, installs screen bis-water of anode electrolysis defat 5min
Wash bis-washing pure water of activation 1min and wash plating hard chrome (mechanical agitation) secondary washing pure water
Wash and unload hanger
Craze of coating.
Embodiment 4: base material 65Mn steel standard test piece (100*50*2mm)
Hanger on mechanical polishing pre-chemical degreasing 10min-, installs screen bis-water of anode electrolysis defat 5min
Wash activation 1min bis-times washing pure water to wash plating hard chrome (air stirring) secondary washing pure water and wash
Unload hanger
Craze of coating peeling.
No. 45 steel shaft-like parts of embodiment 5 base material (the long 200mm of diameter 30*)
Technological process:
Hanger on mechanical polishing pre-chemical degreasing 10min-, installs screen bis-water of anode electrolysis defat 5min
Wash activation 1min bis-times washing pure water to wash plating hard chrome (soft start, negative electrode keeps static, and solution is without stirring
Mix) secondary washing pure water washes and unloads hanger dehydrogenation
Plating hard chrome condition: 50 DEG C, 90A, PH=1.4, electroplate 20min, uniformly, thickness reaches 44um, hardness to coating light
Reaching 880HV (1050HV after heat treatment), adhesion passes through thermal shock test (200 DEG C of heating, salt water quick cooling).
Enforcement real 6: base material 65Mn steel shaft-like part (the long 200mm of diameter 30*, wherein 50mm length in the middle of parcel plating)
Technological process:
Hanger on mechanical polishing pre-chemical degreasing 10min-, installs screen, non-plated position insulation processing anode electrolysis
Defat 5min bis-washing pure water of bis-washing activation 1min wash plating hard chrome (soft start, negative electrode
Keeping static, solution is without stirring) secondary washing pure water washes and unloads hanger dehydrogenation
Plating hard chrome condition: 50 DEG C, 22A, PH=1.4, electroplate 20min, uniformly, thickness reaches 45um, hardness to coating light
Reaching 870V (1048HV after heat treatment), adhesion passes through thermal shock test (200 DEG C of heating, salt water quick cooling).
Embodiment 7: base material 65Mn steel standard test piece (100*50*2mm)
Technological process:
Hanger on mechanical polishing pre-chemical degreasing 10min-, installs screen bis-water of anode electrolysis defat 5min
Wash activation 1min bis-times washing pure water to wash plating hard chrome (soft start, negative electrode keeps static, and solution is without stirring
Mix) secondary washing pure water washes and unloads hanger dehydrogenation
Plating hard chrome condition: 50 DEG C, 45A, PH=1.4, electroplate 20min, uniformly, average thickness reaches 40um to coating light,
Hardness reaches 890V (1030HV after heat treatment), and adhesion passes through thermal shock test (200 DEG C of heating, salt water quick cooling).
Claims (5)
1. an electro-plating method for Trivalent hard chromium, comprises the steps:
A) workpiece pre-treatment, it is necessary to workpiece carries out oil removing, eliminates rust and clean up, dilute sulfuric acid activates；
B) workpiece dress puts into Trivalent hard chromium electroplating solution after hanging；
C) plating startup must use soft start, i.e. the time 1～5min, current potential is changed stepwise as selection of appointed by 0V；Electric current density is by 0A progressively
It is changed to given current density；
D) electroplating parameter controls current density range is 25～75A/dm2；
E) electroplating solution temperature controls as room temperature～60 DEG C；
F) in electroplating process, electroplating cathode is immovable, and solution can not use the method that circulating filtration, mechanical agitation force solution flowing；
Described Trivalent hard chromium electroplating solution mainly includes trivalent chromium sulfate, chelating agent, catalyst and buffer agent, wherein trivalent chromium sulphuric acid
Salt can be chromic sulfate or chromic potassium sulfate, and in solution, the concentration of trivalent chromic ion is 23.9～40g/L；Chelating agent can be nitrilotriacetic acid,
Oxalic acid, malic acid, glycine, formic acid, acetic acid or its sodium salt, potassium salt, at least contain one of which chelating agent, content be 1～
60g/L；Catalyst can be potassium bromide, potassium fluoride, ammonium fluoride or sodium fluoride, at least contains one of which catalyst, and content is
5～50g/L；Buffer agent can be aluminum sulfate, boric acid, phthalic acid, at least contains one of which buffer agent, content be 120～
150g/L；Solution ph is 1.2～2.1.
2. the electro-plating method of Trivalent hard chromium as claimed in claim 1, it is characterised in that the compound method of described Trivalent hard chromium electroplating solution is:
First the deionized water of metering 2/3rds put into container and is heated to more than 60 DEG C, main salt being added in deionized water while stirring, then
It is sequentially placed into chelating agent, catalyst and buffer agent, after all dissolving, retains stand-by；Will be less than the deionized water of metering 1/3rd
Put into other container and be heated to more than 60 DEG C, buffer agent being put into while stirring in the deionized water of this container, after all dissolving, will
Solution in second container pours first container into, is heated to about 95 DEG C and is incubated more than 2 hours, when temperature Temperature fall is to technological temperature,
Using deionized water constant volume, electroplating solution has been prepared.
3. the method for claim 1, it is characterised in that the electric current density described in step (4) is 35～60A/dm2。
4. the method for claim 1, it is characterised in that the temperature controlling range described in step (5) is 40～55 DEG C.
5. method as claimed in claim 4, it is characterised in that temperature controlling range is 45～50 DEG C.
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| CN201210210952.7A CN103510130B (en) | 2012-06-26 | 2012-06-26 | Trivalent hard chromium electro-plating method |
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| CN103849908B (en) * | 2014-02-17 | 2016-04-20 | 惠州大亚湾达志精细化工有限公司 | A kind of trivalent chromium bath and in trivalent chromium bath the method for electrodeposited chromium coating |
| CN105063676A (en) * | 2015-08-17 | 2015-11-18 | 内蒙古第一机械集团有限公司 | Method for electroplating hard chromium by using trivalent chromium |
| CN105386089B (en) * | 2015-12-25 | 2018-04-24 | 武汉迪赛环保新材料股份有限公司 | A kind of Trivalent hard chromium electroplating solution and its application in hard chrome plating |
| CN107675215A (en) * | 2017-08-25 | 2018-02-09 | 刘建伟 | A kind of gear electroplating solution |
| CN109371433B (en) * | 2018-10-31 | 2019-09-20 | 中国人民解放军陆军装甲兵学院 | A kind of preparation method of nanocrystalline trivalent chromium composite deposite plating solution and composite deposite |
| CN111020655B (en) * | 2019-11-25 | 2021-10-08 | 厦门大学 | Preparation method and application of zirconium alloy material with chromium coating |
| CN112609216A (en) * | 2020-11-30 | 2021-04-06 | 中船重工重庆液压机电有限公司 | Electroplating method for improving corrosion resistance |
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| USRE29749E (en) * | 1973-12-13 | 1978-08-29 | Albright & Wilson Ltd. | Trivalent chromium electroplating baths and electroplating therefrom |
| GB2109816B (en) * | 1981-11-18 | 1985-01-23 | Ibm | Electrodeposition of chromium |
| US7052592B2 (en) * | 2004-06-24 | 2006-05-30 | Gueguine Yedigarian | Chromium plating method |
| CN101629311A (en) * | 2009-08-10 | 2010-01-20 | 安庆师范学院 | Trivalent chromeplating process and plating solution thereof |
| CN101748449A (en) * | 2010-01-19 | 2010-06-23 | 上海应用技术学院 | Method for plating chromium by using trivalent chromium |
| CN102443825B (en) * | 2011-12-07 | 2014-03-26 | 湖北振华化学股份有限公司 | High-concentration chromium sulfate-ammonium fluoride trivalent chromium electroplating solution and preparation method thereof |
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