ALL OUT ZINCOBRITE CLZ ­ 0144 M/R 

Both the addition agents are requried for initial bath make up and for repleanishing during  working of the bath solution. Zinc deposits produced from the system, readily accept any conventional chromate passivation treatment from blue, irridescent golden, olive green or black chrome passivation treatment from blue, irridescent golden, olive green or black chrome passivation for detailed operation of passivation treatment see our zinchromate 161, (l), 162(p), 164 and 171 pamphlets.

The escort acid zinc process produces an acceptable finish from a wide range of bath compositions. It is advisable to maintain the bath within recommended limits in order to minimize the chemical consumption and to get consistent results. The recommended bath make up, working conditions, maintenance and consumption of the bath constituents are given as under.

Bath make up :-  

Hydrogen peroxide  (30% 10o volume  per day) for 1000 litre bath                100      25

Note :-  To be addee per day or weekly basis. To increase 1.0 gm/liter of zinc metal add   3.4  litre Of 241a liquid for a 1000 liter bath.

Note  :-  After  addition,  air  agitate  the  bath  for  half  an  hour and  do  filtration  priod  to  start  plating  work on  next day so that the bath will be free from iron  impurities

Bath solution preparation :

The recommended solution preparation procedure is given as under :-

1.    The plating tank must be leached, cleaned and rinsed thoroughly prior to solution preparation.

2.    Fill the cleaned and rinsed plating tank about three quarter full of softened or demineral ise water. Heat to a temperature of 55-60^oc.

3.    Dissolve required quantity of acid zinc salt 241 b, stir vigorously with air and a plastic paddle until all the salts are completely dissolved.

4.    Add required quantity of liquid 241 a with stirring.

5.    Check the ph of the solution with a ph meter or ph paper. Adjust if necessary to 4.8 to 5.0 with chemically pure grade hydrochloric acid to lower the ph or with 20% solution of caustic potash to raise the ph.

6.    Filter the solution till free from any suspended matter. Clean the filter cartridges and cloths. Repack with activated carbon and cyn zinc purifier 214 s. Filter the solution.

7.    Add required quantity of carrier 0144m and brightner 0144 r with stirring.

8.    Add sufficient water to bring solution level to final operating volume.

9.    Put necessary number of anodes and use the bath for the plating.

Plating sequence:-

A suitable sequence for the preparation of parts for acid zinc plating is as follows:-

1.    Hot soak clean at 70^oc using 70 gm/litre of cleaner ms-120 r for 3 to 5 minutes.

2.     hot soak clean at 70^oc using 50 gm/ltr of cleaner ms-112, at  4-6 volt for 2 to to 3 minutes (do if required)

3.    Swil in gold running water.

4.     pickel in 50% v/v hydrochloric acid.

5.     water rince(twice) do not keep cleaned parts/components in rinse after for a longer time.

6.    Do escort acid zinc plating for a required time. Insure that parts taken for plating are completely cleaned and not resrusted other wise parts after plating and subsequent passivation will be hazy and not fully bright.

7.    Swil in running water.

8.    Passivate as desired.

9.    Swill in cold running water.

10.Dry and pack. 

Note: the preferred, conventration of chromate solutions are usually more dilute than required for cyanide zinc plating.

Equipments:-

Tank :-

Mild  steel  tanks lined with pvc or polypropylene are suitable.  The  tank Must be thoroughly cleaned before final use. The tank should be fitted with Twin  row plastic air agitation pipes. As an alternative to air  agitation, Mechanical cathode rod movement may be employed. Where high current density Loading are used e.g. in barrel plating, solution cooling will be Necessary and titanium cooling coils will need to be fitted.

Filtration:-

Both barrel and rack plating installations require continuous filtration to remove iron sludge. The filtration system should have sufficient capacity to filter the plating solution two times per hour. All the inside parts of the filter unit should be made up of approved quality hard rubber.

Aoitation:-

Low pressure or oil free air equipment is recommended for air agitation of the bath solution, compressed air coming from a conventional air compressor should not be used.

Anodes:-

Anodes used are of 99.99% pure special high grade zinc. Flat top, ball, oval or slab anodes may be used. Ball anodes in titanium baskets may be used. It is essential to keep the anode baskets filled with zinc balls to avoid corrosion of titanium baskets. 

Anode area must be sufficient to keep anode current density below 3 amp/sq.dm. Do not use any inert anodes. 

It is most desirable to use anode  bags of polypropylene for rack plating. If anodes are not bagged properly then roughness on plated surfaces will be noted. Anode bages should be cleaned periodically. 

Power supply:-

For rack plating 4-6 volt rectifier is adequate. While 6-9 volt source is required for barrle plating. Rectifiers must have low ripple(5% maximum) factor.

Bus bars:-

All copper bus bars used over the tank should be either dull nickel plated with a thickness of 50-100 microns or insulated by taping them with plastic shields to prevent corrosion and subsequent contamination of the solution. 

Role of bath constituents:-

Escort acid zinc liquid 241 a:-

Provides all the zinc ions for make up 3.3 ml/litre of 241 a will be required to increase 1.0 gm/litre of zinc metal and 1.0 gm/litre of total chloride. By increasing the concentration of 241 increases the permissible current density.

Escort acid zinc salt 241 b:-

It is a main source of chloride ions and boric acid. It increases the conductivity. Covering and throwing power of the bath. It provides 42% of total chloride and 12% of boric acid.

Escort acid zinc carrier 0144 m:-

Carrier 0144m is our recently developed new formulation, required for intital make up and maintaining the bath alongwith brightner 0144r. The main functions of carrier 0144 m are to act synergistically with brightner  0144 r to maintain maximum grain refining, leveling and brightness, as well as low current density brightness and coverage. If its concentration decreases below the recommended level, it leads to hazy dull deposits or roughness in the high current density are and poor low current density coverage. It is consumed by electrolysis and removed by drag out losses.

Ecort acid zinc brightner 0144 r:-

It is used to maintian maximum rate of leveling and to get extrmely bright finish. A low concentration will results in overall loss of brightness, leveling and performance. Factor influencing brightner consumption are drag out losses, temperature and current density. Frequent small additions are more economical then large occasional ones. This assures a concentration in the tank at all times and provides the most economical, trouble free method of operation.

Effluent treatment:-

Detoxification of escort acid zinc process 0144 m/r solution is very simple, as compare to cyanide zinc process. Collect the waste water in a container, neutralised it to a ph 7.5 to 8.5 by adding 25% solution of caustic sode with enough stirring. This will precipitate the zinc as hydroxide sludge which can be removed by filtering the solution of by allowing the sludge to settle and decanting the solution. Local regulations regarding sludge disposal should be followed or it should be sold to zinc recovery plant. Clear liquid can be discharged into  a sewage system, assuring there are no other pollutants present.

         Specification Requirement and rate of deposition r a c k  Plating:

Rate  of  deposition at various current densities and  voltage  to  achieve Minimum and average thickness in minutes.

·     This is in consideration to general observations, but actual variation in thickness is depending upon the shape and dimension of the components.

·     Depending on optimum conditions of the bath.
barrel plating.

Rate of deposition on threaded parts e.g screws, bolts, nuts ect. Considering 85% cathode efficiency.