Nichel Sulphamate Bath

NICKEL SULPHAMATE 1also available online at www.growel.com

NICKEL SULPHAMATENickel Sulphamate is offered as a purified concentrate; which has been treated to remove both organic andinorganic impurities. It contains no addition agents; therefore it may be used as a base for a new nickelsulphamate bath, or merely to replenish the nickel content of an existing nickel sulphamate solution.

Nickel Sulphamate offers several advantages over the nickel plating baths.1. It is capable of producing stress free deposits than other nickel plating baths.2. It produces ductile fine grained hard deposit.3. It operates at a high rate of deposition.4. It is a concentrated liquid.5. It may be operated at high current densities.6. It has a very high cathode efficiency.7. Its deposit has high tensile strength.

APPLICATIONS

1. Electroforming.2. Electrotypes and stereotypes.3. Manufacture of sieves for sugar refining.4. Electronic components.5. Roller coating.6. Rebuilding of worn parts.7. Jet Engine overhaul.

Typical analysis of the Nickel Sulphamate concentrate :

Nickel Sulphamate 550 g/lNickel (as metal) 100 g/l

PHYSICAL PROPERTIES

Specific gravity .. 1.30 - 1.34Density .. 33 - 35 OBeColour .. Green

TECHNICAL DATA SHEET


PREPARATION OF CONVENTIONAL BATH

A 100 litre Bath requires :Nickel Sulphamate conc. .. 75.0 litresNickel Chloride .. 1.5 kgs.Boric Acid .. 3 kgs.Water .. To make 100 ltrs.Antipit A/P No. 2 .. 0.01 to 2 g/lCathode movement .. 2-10 gms

COMPOSITION OF THE CONVENTIONAL BATH

Optimum RangeNickel (as metal) g/l 75 75-100Nickel Chloride g/l 15 15-30Boric Acid g/l 30 26-35

OPERATING CONDITIONS

Density ... 29-31 OBeTemperature ... 40-50 OCpH ... 3.5 to 4.5Current density ... 2.0 to 8.0 amps/dm2Anodes ... Bagged, S-Nickel/Pallets in titanium basketsAnode to Cathode Ratio ... 1:1Voltage ... 2 to 8

AVERAGE PHYSICAL PROPERTIES OF THE DEPOSIT FROM NICKEL SULPHAMATE, BROMIDEBATH :

Tensile strength ... 103,000 PSIInternal stress ... 500 to 8000 PSIHardness ... 170 to 300 VHN (12 to 21 Rockwell)

NOTES ON OPERATING PROCEDURES

Bath purification and adjustment :

After make-up, the bath should be carbon treated and dummied, using a corrugated Cathode. The dummyingshould be conducted 5 amps/sq. ft. at Anode and Cathode and should be continued until a uniform plateis achieved in both low and high current density areas. A practical method is to treat overnight.

For proper conditioning of Sulphamate bath, it is preferable to electrolyze the solution further at5 amp/sq. ft, anode 40 amps/sq. ft. cathode for minimum of 30 Ahr/litre or till such time the depositis stress free.

It is desirable to have continuous dummy treatment at 5 amp/sq. ft. The pH should be checked and iffound to be over 4.5, small additions of sulphamic acid should be made until it is in the 3.5 to 4.5 range.

It it is found to be only slightly under 3.5 it would not be necessary to make an adjustment because ofthe tendency of the pH to rise in normal operation; if it is found for some reason to be considerably below3, then a powder of nickel carbonate placed in a polypropylene filter bag should be suspended until thedesired pH is obtained.


Filtration Agitation :

For best results the bath should be subjected to constant filtration of about 3-4 changes/hr. This will servea two fold purpose of cleaning the bath and affording the solution the agitation it requires to assure uniformdeposits.

ROLE OF BATH COMPONENTS

Nickel Sulphamates :Nickel Sulphamate furnishes nickel ions and sulphamate ions to the bath. The Sulphamate ions give lowstress characteristics to the deposits.

Nickel Chloride :One of the primary reasons for plating nickel from a Sulphamate bath is to produce a deposit with lowtensile stress. A pure nickel sulphamate plating solution deposits nickel with little stress, but the anodecorrosion in a pure nickel sulphamate solution is poor. In order to obtain good anode corrosion, nickelchloride has been added to the sulphamate in concentrations of 15-30 g/l.

Antipit :Prevents pitting by controlling the surface tension of the solution.

Boric Acid :Boric Acid buffers and stabilizes the bath.

EFFECT OF VARYING THE OPERATING CONDITIONS ON THE DEPOSITS

Temperature :Increase the temperature from 25 to 40 OC. Reduces the stress. Above 40 OC the stress increases slightly;but does not climb appreciably until the temperature rises above 50 OC. Operating temperature lower than35 OC results in harder deposits.

Current density :The higher the current density, lower the stress & higher the current density, softer the deposit.

pH :Optimum pH for low stress is at 4. Below 4 the stress increases slowly at a pH of 5 it rises sharply. Thehigher the pH the harder the deposit.

Trouble shooting

Burned deposits :Low temperatureHigh current densityLow concentrationPoor agitation

Pitting :Low Antipit concentration or organic contamination.

Treeing, rough deposits :pH, out of range - Use sulphamic acid to lower pH, nickel carbonate to raise pH.Bath dirty / suspended impuritiesHigh current densityPoor agitationOrganic / metallic contamination


Difficulty in maintainig pH :

Check Boric Acid. Good procedure is to leave an anode bag full of boric acid in the dummying sectionof the tank until the boric acid concentration is around 30-35 g/l.

Non-Uniform plate :Inorganic impurities. Bath should be dummied.

Low rate deposition :pH lowCurrent density lowInorganic impurities

Brittle deposits :Organic contamination, Carbon treatpH high.

Equipment :Tanks - Approved Rubber lined, Polyethylene, Fibreglass, PVCHeaters or heat exchangers - Silica / TitaniumFilters - Approved Rubber lined, PVC, Polyethylene

Control of Bath :Density and pH provide most of the answers for daily control. An analytical procedure for nickel, chlorideand boric acid is as follows :-

ANALYSIS OF THE NICKEL SULPHAMATE BATH

Nickel :

1. Pipette 2 ml sample of bath.2. Add ammonia to deep blue colour.3. Add 1 murexide tablet or 3 to 6 drops of saturated solution of murexide.4. Titrate with a standard 0.1M solution of disodium EDTA till end point; indicated by a sharp colour

change from green to deep blue.

Calculations :ml EDTA X 2.934 = gms/lit. of Nickel

Boric Acid :

1. Pipette 1 ml sample of bath2. Add 5 gms. of Boric Buffer into Erylenmeyer flask.3. Add 10 drops of Methyl red.4. Titrate with 0.1N Sodium Hydroxide mixing very well to green end point.

Calculations :ml of Sodium Hydroxide X 6.184 = gms/lt of Boric Acid

Chloride determination :

1. Pipette 5 ml sample of nickel sulphamate solution into a 250 ml Erlenmeyer flask.2. Add approximately 100 ml distilled water.3. Add 2 ml of glacial acetic acid.4. Add 5 drops of Potassium Chromate.5. Titrate with 0.1N Silver Nitrate to faint reddish brown.

Calculations :ml of Silver nitrate X 2.378 = gms/lt of Nickel chloride


DEPOSITION OF NICKEL FROM SULPHAMATE SOLUTION

THICKNESS IN INCHES

Amps/sq.ft. .0001 .0003 .0005 .0007 .001 .002

10 12 36 60 84 120 24020 6 18 30 42 60 12030 4 12 20 28 40 8040 3 9 15 21 30 6050 2.4 7.2 12.2 16.7 24 47.7100 1.2 3.6 6.1 8.4 12 24

Issued on : 9.8.04Supersedes all earlier

Nichel Sulphamate Bath

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