Alkaline Zinc Iron Electroplating Chemicals
ALKALINE NON CYANIDE ZINC-IRON PROCESS
FEZINK 206 is an alkaline zinc-iron electroplating process with good metal distribution properties, which adds to the traditional qualities of the FEZINK process the anti-corrosion properties and yellow and black finish requirements demanded by the automotive sector. In excess of 200 hours salt spray after thermal shock (1 hour at 120°C).
MAKE-UP
- Fill the tank one third full with water, preferably Dl water.
- Add the required amount of sodium hydroxide bit-by-bit with vigorous mixing (the reaction is highly exothermic; ensure the tank lining can withstand the temperature reached).
- Dissolve the zinc metal required.
- Allow solution to cool to 30°C.
- Add FEZINK Purifier 0.5 – 1.0 ml/l
- Give Dummy to the solution for few hours.
- Add FEZINK Brightner at the rate of 8 – 10 ml/l
- Put the solution under continuous filtration.
- Add FEZINK 206 Complex at the rate of 75 ml/l.
- Add FEZINK 206 Iron Additive at the rate of 3.5 ml/l.
- Put the solution under continuous filtration for at least 4 – 6 hours.
MAKE-UP QUANTITIES
| FOR RACK & BARREL | RANGE | OPTIMUM |
|---|---|---|
|
CAUSTIC SODA |
110 – 130 g/l | 120 g/l |
|
ZINC METAL (99.99 PURITY) |
9 – 10 g/l | 11 g/l |
|
IRON |
50 – 120 ppm | 70 ppm |
|
FEZINK 206 COMPLEX |
70 – 80 ml/l | 75 ml/l |
| FEZINK 206 PURIFIER | 0.5 – 1.0 ml/l | |
| FEZINK 206 BRIGHTNER | 8 – 12 ml/l | 10 ml/l |
OPERATING CONDITIONS
| BARREL | RACK | |
|---|---|---|
|
TEMPERATURE |
24 – 27ºC | 24 – 27ºC |
|
CATHODE CURRENT DENSITY |
0.5 – 1.0 A/dm2 | 1 – 3 A/dm2 |
|
VOLTAGE |
10 – 20 Volt | 70 ppm |
|
CURRENT LOADING A/LITR 0.7 MAXIMUM |
REPLENISHMENT PER 10000 AHR (BOTH RACK AND BARREL)
FEZINK 206 Purifier – 2 litres FEZINK 206 Purifier per 50 kg of Sodium Hydroxide added
or 0.4 ml/l at each line start-up
FEZINK 206 Brightner – 1 – 2 litres
FEZINK 206 Complex – 6 litres per 8 kg Sodium Hydroxide added
FEZINK 206 Iron Additive – 0.5 – 2 litres
CONTROLS OVER BATH CONSTITUENTS
Sodium Hydroxide consumed through drag – out. Control through analysis
Zinc Metal Control through analysis
This concentration of zinc should be controlled by use of an appropriate ratio of soluble anode
(zinc) surface and insoluble anode (mild steel) surface. During period of no production, zinc in
contact with steel baskets dissolves and concentration in the bath increases, this dissolution
rate increases with concentration of sodium hydroxide. It is therefore essential to remove the
soluble anodes from the tank during stoppage period.
In large volume installation, this requirement may be avoided by the following method:
The working tank is equipped only with insoluble steel anodes, the necessary zinc dissolution to maintain electrolyte equilibrium is carried out in an auxiliary tank, connected to the working tank.
FEZINK 206 BRIGHTNER
This brings brightness to the deposit. It need not be used if appearance requirements are not critical.
FEZINK 206 PURIFIER
This precipitates out metallic impurities which are inevitable in any treatment line. An excess is not harmful, but can turn the solution slightly cloudy. In this case, an addition of up to 5 ml/l bleach is required to produce a clear solution. Where the deposit at low cathode current densities is black, an addition of 2 – 4 ml/l FEZINK 206 Purifier will, in the majority of cases, cure this problem.
FEZINK 206 COMPLEX
This maintains iron in solution and prevents its precipitation.
FEZINK 206 IRON ADDITIVE
This additive contains iron. An addition of 0.35 ml/l increases the iron content of the bath by 10 ppm.
EQUIPMENT
All equipment must be thoroughly cleaned prior to use.
- Tank: Mild Steel or suitably lined.
- Anodes: It is recommended to use insoluble mild steel anodes of 3 -4 mm thickness to obtain a 1:1 anode / cathode ratio. The metal concentration in solution is maintained through the dissolution of zinc balls, bars, ovals or plate anodes (99.99% pure)
contained in iron baskets. Dissolution is encouraged if the steel surface area in contact with zinc is as large as possible (sand blast or shot blast steel).
- Agitation: Mechanical agitation is recommended. Air agitation is not desirable.
- Filtration: Continuous at the rate of 1-2 tank turn overs per hour. Use Plate or cartridge filter of porosity 10µm optimal filtration is necessary to obtain full brightness; presence of suspended particles will lead to mat deposit and risk of blistering.
- Extraction: Desirable
- Heating and Cooling: Steel or titanium (24 – 40°C).
PROCESS SEQUENCE
The quality of deposit obtained depends upon the proposed pre-treatment sequence. Use on non-ionic surfactants is highly recommended throughout preparation sequence.
For steel, following sequence is recommended.
1. Immersion clean
2. Water rinse
3. Pickle
4. Water Rinse
5. Electro – clean
6. Water Rinse
7. Activation
8. Water Rinse
9. Static Rinse prior to zinc plate
10. Zinc plate
11. Water rinse
12. TRIBLAK Passivation
13. Water rinse
14. Topcoat
15. Dry
HEALTH & SAFETY:
Keep containers tightly closed when not in use. Store in dry place and protect from dust. Wear eye/face protection, gloves and protective clothing. Avoid contact with eye and skin, in case of contact, wash with fresh water, and avoid breathing fumes, mist or sprays.
EFFLUENT TREATMENT
Mix vigorously and reduce the pH to 9.00 with dilute acid. Filter out or clarify and decant off the precipice zinc. Adjust the pH of the filtrate according to local pollution control regulation before discharge.
DISCLAIMER
Our recommendations are made in good faith and are based on our skill and experience. As conditions of use are normally not in our control nor ideal. Ronuk does not give any guarantee or warrantee explicit or implicit and we are not liable to any person or corporate by reason thereof.