1、Designation: B343 92a (Reapproved 2014) Endorsed by AmericanElectroplaters SocietyEndorsed by NationalAssociation of Metal FinishersStandard Practice forPreparation of Nickel for Electroplating with Nickel1This standard is issued under the fixed designation B343; the number immediately following the
2、 designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This practice summarizes
3、well-known, generally practi-cal methods for producing adherent electrodeposits of nickelon nickel.1.2 Electrodeposits of nickel on nickel are produced, forexample, to improve the performance of decorative coatings, toreclaim electroplated parts that are defective, and to resumenickel electroplating
4、 after interruptions in processing. Interrup-tions may be deliberate, for example, to machine the electrode-posit at an intermediate stage in the electrodeposition of thicknickel coatings. The interruptions may be unintentional, forexample, resulting from equipment and power failures.1.3 To ensure g
5、ood adhesion of nickel to nickel, precautionsshould be taken to avoid biopolar effects during nickel elec-troplating. This is of particular importance in return-typeautomatic plating machines where one rack follows anotherrack closely. Bipolar effects can be avoided by making theracks cathodic while
6、 they are entering or leaving the nickeltank. Separate current control on entry and exit stations isdesirable.1.4 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.5 This standard does not purport to address all of thesafety con
7、cerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Types of Nickel2.1 The types of nickel for which an overplate of nickel maybe
8、desired are dull nickel, semi-bright nickel, bright nickel, andnickel strike. Variations in these types may possibly requirespecial handling.2.2 Surface conditions of the nickel may vary as follows:2.2.1 Freshly electroplated surfaces that are still wet withelectroplating solution or rinse water (se
9、e 5.1),2.2.2 Freshly electroplated surfaces that have been allowedto dry (see 5.2),2.2.3 Buffed, polished, or machine-ground surfaces (see5.3), and2.2.4 Surfaces that have been given a reverse-current treat-ment in an alkaline solution for cleaning or possibly strippingan overplate of chromium (see
10、5.4).3. Cleaning3.1 The following cleaning treatments may be used for allconditions and types of electrodeposited nickel. The choice ofthe procedure will be governed largely by the condition of thesurface.3.1.1 DegreasingDegreasing is used to remove the bulkof grease, oil, and buffing compounds that
11、 may be present onthe surface. The cleaning may be effected with vapordegreasing, organic solvents, emulsion cleaners, or soakcleaner.3.1.2 Electrolytic Alkaline CleaningRemoval of finaltraces of dirt, grease, and oil is accomplished best withelectrolytic alkaline cleaning. The solution may be eithe
12、r aproprietary cleaner or a formulated one. Since a nickel surfaceforms an oxide coating if treated anodically in an alkalinesolution, this condition must be altered in subsequent steps if itcannot be avoided.4. Activating4.1 The procedure used for etching or activating the nickelsurface usually det
13、ermines the soundness of the adhesion. Thechoice of the procedure may be governed by the condition ofthe surface and possibly the type of nickel. The milder etchingtreatment should be used in the case of highly finishedsurfaces, but it may result in sacrificing maximum adhesion.The thickness of the
14、nickel may militate against the use ofcertain etching procedures, and therefore the thickness re-moved is indicated for each procedure described in 4.2 to 4.8.4.2 Anodic Treatment in Concentrated Sulfuric Acid(Nickel removed nil). A70 mass % sulfuric acid solutioncontaining 661 mL of concentrated, 9
15、6 mass % sulfuric acid1This practice is under the jurisdiction of ASTM Committee B08 on Metallicand Inorganic Coatings and is the direct responsibility of Subcommittee B08.02 onPre Treatment.Current edition approved Nov. 1, 2014. Published November 2014. Originallyapproved in 1960. Last previous edi
16、tion approved in 2009 as B343 92a (2009).DOI: 10.1520/B0343-92R14.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1(density 1.83 mL) diluted to 1 L may be used for activating thenickel surface provided the temperature of the solution i
17、s notover 30C (see Warning). When the initial mixture cools,dilute to exact volume. The time of treatment should be about1 min at a current density of 10 A/dm2. At this current densitythe nickel normally goes passive and a bright surface becomesonly slightly dull. This type of passivity is removed b
18、ysubsequent rinsing in water. (WarningSlowly add the sul-furic acid with rapid stirring to the approximate amount ofwater required.)4.3 Anodic Etching in Sulfuric Acid(Nickel removedapproximately 1.3 m.) A25 mass % sulfuric acid solution,containing 166 mL of concentrated, 96 mass % sulfuric acid(den
19、sity 1.83 g/mL), diluted to 1 L is used for this anodicetching treatment in which the nickel surface is first etched ata low current density of 2 A/dm2for 10 min and then madepassive at 20 A/dm2for 2 min and finally cathodic for 2 or 3 sat 20 A/dm2. See Warning in 4.2. The temperature of thesolution
20、 should be kept below 25C. This treatment results inexcellent adhesion, but the amount of etching makes it lessdesirable for a highly finished surface.4.4 Anodic Etching in Watts-Type Bath(Nickel removedapproximately 4 m.) This procedure employs an anodictreatment in a low-pH Watts bath for 3 min at
21、 1 A/dm2(10A/ft2), followed by cathodic treatment for 3 to 6 min at 3A/dm2(30A/ft2). The composition of the solution is 240 to 300g/L nickel sulfate (NiSO47H2O), 40 to 60 g/L nickel chloride(NiCl26H2O), and 25 to 40 g/L boric acid. It is operated at atemperature between 25 and 50C and at a pH betwee
22、n 1.5 and2.0. An additional bath is not required if a means of reversingthe current is available. The amount of etching obtained issufficient to dull a bright surface, and there is danger of bathcontamination from bare areas.4.5 Acid-Nickel Chloride Treatment(Nickel removed ap-proximately 1.3 m.) Th
23、is procedure employs an anodictreatment followed by a cathodic treatment in a low-pH nickelchloride solution. The composition of the solution is 240 g/L ofnickel chloride (NiCl26H2O) and 31 mL of concentrated, 37mass % hydrochloric acid (density 1.16 g/mL). The normalprocedure is to make the work an
24、odic for 2 min at 3 A/dm2andthen cathodic for 6 min at the same current density. Where it isnot possible to reverse the current in the same tank, the twosteps may be carried out in separate tanks. The latter arrange-ment may be more practical commercially. This treatmentproduces a dull finish on a b
25、right surface, but the etching is notsufficiently drastic to preclude finishing with bright nickeldeposit.NOTE 1Nickel anode materials containing greater than 0.01 mass %sulfur are not recommended for use in acid nickel strike baths operatingat pH 0.5, or lower, to avoid oxidation of sulfides by hyd
26、rochloric acid.4.6 Etching by Acid Immersion(Nickel removed approxi-mately 1.3 m.) Adequate etching may be obtained on somenickel surfaces by a short dip at room temperature in a solutionof either 500 mL of concentrated 37 mass % hydrochloric acid(density 1.18 g/mL) diluted to 1 L, or 150 mL of conc
27、entrated96 mass % sulfuric acid (density 1.83 g/mL) diluted to 1 L. See4.2. The length of the immersion required may vary from 10 sto 1 min.4.7 Electropolishing Treatment(Nickel removed approxi-mately 1.3 m.) This procedure is commonly employed onrejects that have been repolished to remove the defec
28、tive area.The electropolishing solution commonly used consists of amixture of 150 mL of 96 mass % sulfuric acid (density 1.83g/mL) and 630 mL of 85 mass % phosphoric acid (density 1.69g/mL) diluted to 1 L. See Warning in 4.2. Temperature ofsolution ranges from 45 to 55C. The work is made anodic atcu
29、rrent densities from 15 to 20 A/dm2. The electropolishingtreatment is usually applied for 2 to 15 min. The cathodes maybe electrolytic nickel strip. Subsequent alkaline cleaning andan acid dip are normally used before electroplating.4.8 Cathodic Treatment(Nickel removed nil.) These pro-cedures are r
30、ecommended where the nickel surface has notbeen severely passivated. Prior cleaning may be required, suchas alkaline soak cleaning or electrocleaning, or both. Ifelectrocleaning is employed, only cathodic current should beused. In the following formulations, 96 mass % sulfuric acidwith a density of
31、1.83 g/mL, and 37 mass % hydrochloric acidwith a density of 1.16 g/mL, are used.4.8.1 Cathodic Treatment in Sulfuric Acid:Sulfuric acid 30 to 100 mLWater to1LTemperature ambient to 45CCurrent density 1 A/dm2Anodes pure leadTime 30sto5min4.8.2 Cathodic Treatment in Hydrochloric Acid:Hydrochloric acid
32、 100 to 300 mLWater to1LTemperature ambientCurrent density 1 A/dm2Anodes electrolytic nickel strip or nickelbar anodesTime 30sto5minNOTE 2In some instances, the use of 2 g/L of ammonium bifluoride(NH4 HF) has been found to be beneficial in either of the aboveformulations.NOTE 3Proprietary acid salt
33、formulations may be used with thesuppliers recommendations.5. Electroplating Procedures5.1 Wet Freshly Electroplated SurfacesNickel surfacesthat are still wet with electroplating solution can sometimes beplaced directly in the subsequent nickel electroplating bathwithout any special treatment. If th
34、e solutions are notcompatible, a water rinse may be used between nickel baths.This procedure will normally give good adhesion with Watts-type nickel and certain semi-bright nickels but may give pooradhesion with bright nickels. A mild etch, such as a shortB343 92a (2014)2immersion in a dilute acid s
35、olution, may be required for somesemi-bright and bright nickel surfaces.5.2 Dry Freshly Electroplated SurfacesNickel surfacesthat have been allowed to dry following the rinse from theelectroplating bath may only require an activation treatment.However, if there is a possibility of a trace of oil or
36、grease onthe surface, a cathodic alkaline cleaner should be used first. Ashort immersion in a dilute acid solution should be adequate toactivate most nickel surfaces, but certain bright nickels mayrequire more drastic activation.5.3 Polished, Buffed, or Machine Ground SurfaceThesenickel surfaces can
37、 usually be treated alike for nickelelectroplating, although the buffed surface will require moredrastic degreasing treatment and alkaline cleaning. For deco-rative surfaces, a mild etch, such as a short immersion in adilute acid or a short anodic treatment in sulfuric acid, shouldbe adequate to ass
38、ure good adhesion.5.4 Anodic Alkaline Treated SurfaceThe oxide film on anickel surface from anodic treatment in an alkaline solutionmust be removed by a suitable activation treatment before thenickel surface can be electroplated adherently with nickel. Anacid dip or a mild anodic etch in sulfuric ac
39、id is usually notadequate. A heavy anodic etch in sulfuric acid, an electropol-ishing treatment, a low-pH nickel bath, or the acid-nickelchloride treatment will normally be required to provide a sounddeposit. A wipe on a buffing wheel will also serve to removethe oxide film.5.5 Rejects with Chromium
40、 ElectroplateOn parts requir-ing the removal of chromium for reprocessing, use of an anodicalkaline chromium strip should preferably be avoided. Acidstripping should be used. If an anodic alkaline strip is used,then an anodic acid etch is absolutely necessary.ASTM International takes no position res
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43、ational Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown be
44、low.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org). Permission rights to photocopy the standard may also be secured from the Copyright Clearance Center, 222Rosewood Drive, Danvers, MA 01923, Tel: (978) 646-2600; http:/ 92a (2014)3
