Alkaline zinc electrolyte with optimum coating thickness distribution
The alkaline zinc-nickel ensures a uniform coating thickness distribution on the surface over a wide current density range and is free of cyanides. Especially for less complex shaped workpieces, which are deformed after coating with zinc electrolyte, a uniform coating thickness throughout is indispensable. Alkaline zinc electrolyte is characterised by better ductility than acid zinc nickel and, as a basic zinc nickel electrolyte, offers the same high corrosion protection as an acid zinc nickel electrolyte. The very good spreading produces a uniform coating build-up even on profiled workpieces, which effectively prevents the coating from flaking. The alkaline zinc electrolyte was developed for electrogalvanising by means of bath electroplating and pin electroplating / tampon electroplating. The deposition is silk-matt - this is particularly advantageous for corrosion protection, as high-gloss depositions offer poorer protection.
Area of application of zinc-nickel electrolyte
Zinc-nickel alkaline is always used when high corrosion protection and a uniformly thick layer are required. Due to the nickel content of approx. 14%, the corrosion resistance of workpieces treated with zinc-nickel alkaline increases fivefold and offers the highest cathodic corrosion protection. This is an argument in favour of zinc-nickel, especially in corrosion protection. The further treatment of the workpieces after galvanising with zinc-nickel is the same as for coating with conventional zinc electrolyte. Another special feature is that the nickel content of approx. 14% remains almost constant over a wide current density range.
This zinc electrolyte is suitable for the following metals:
- stainless steel - pre-treat with nickel-strike activator
- aluminium - pre-treatment with Aluminium Activator required.
Chrome and titanium are unsuitable.
Application instructions for zinc-nickel
All metals mentioned can be treated with zinc-nickel, whereby stainless steel and aluminium require an appropriate pre-treatment. As a basic zinc electrolyte, zinc-nickel is used both in bath electroplating and in pin electroplating / pad electroplating. In all processes, they achieve excellent results in the form of a uniformly strong layer thickness, which also remains stable during further processing of the workpiece by deformation.
Alkaline zinc electrolyte is processed at room temperature; however, it can also be heated slightly. The temperature range in which this zinc electrolyte can be used for coating is between 15 - 60°C.
The zinc-nickel electrolyte can be further coated or chromated like any other zinc electrolyte. Due to the fact that it deposits silk matt, a further coating adheres particularly well.
Parameters (these may vary, please test):
- tank plating: 2.2-4.5V (approx. 3.5V recommended at 10cm distance)
- brush plating: 2.5-7V (approx. 5V recommended)
- current density: 0.9-8A/dm² (up to 12A/dm² with bath movement)
- working temperature: 15-35°C
- deposition rate: approx. 0.6µm/min at 4A/dm² and 20°C
- ph-value: 14
Nickel or zinc anodes are recommended (anode on positive pole, workpiece on negative pole).
When using a zinc anode, the range is greatly increased, but the nickel content in the solution is reduced over time (the violet colouring of the solution slowly disappears) - it increasingly becomes a pure zinc electrolyte. Due to the composition, the nickel content in the deposit remains constant over a longer period of time.
Before treatment, please thoroughly remove rust, oils and grease from the workpiece. Wear disposable gloves when handling to prevent contamination with skin grease.
Use appropriate protective equipment such as safety goggles and gloves when working with zinc electrolyte. Use only in well-ventilated rooms!
Labelling of the mixture:
Zinc-nickel plating solution
(contains sodium hydroxide, diethylenetriamine, nickel sulfate, nickel dichloride, nickel sulfamate)
Signal word: Danger
H290 May be corrosive to metals.
H314 Causes severe skin burns and eye damage.
H317 May cause an allergic skin reaction.
H332 Harmful if inhaled.
H412 Harmful to aquatic life with long lasting effects.
P101 If medical advice is needed, have product container or label at hand.
P102 Keep out of reach of children.
P260 Do not breathe dust/fume/gas/mist/vapours/spray.
P280 Wear protective gloves and eye/face protection.
P301+P330+P331 IF SWALLOWED: Rinse mouth. Do NOT induce vomiting.
P303+P361+P353 IF ON SKIN (or hair): Take off immediately all contaminated clothing. Rinse skin with water or shower.
P305+P351+P338 IF IN EYES: Rinse cautiously with water for several minutes. Remove contact lenses, if present and easy to do. Continue rinsing.
P310 Immediately call a POISON CENTER/doctor.
P501 Do not discard content with household waste and forward for disposal according to regional/national Guidelines.