ACID AMMONIUM-FREE ZINC-NICKEL PROCESS

Transcription

1 ACID AMMONIUM-FREE ZINC-NICKEL PROCESS PHYSICAL PROPERTIES: ZINNI AC AF 211 Basic solution: ZINNI AC AF 212 Brightener: ZINNI AC AF 213 Buffer: ZINNI AC AF 214 Wetting agent Colourless liquid Light brown liquid White salt Light brown liquid DESCRIPTION: The process is an acid ammonium-free zinc nickel plating system for rack and barrel plating. produces mirror bright, ductile and corrosion resistant zinc nickel deposits with % nickel. It provides excellent covering, throwing power and a wide bright plating range. Zinc nickel plated parts can easily be chromated and passivated. Main advantage of over alkaline zinc nickel processes is the higher current efficiency and therefore reduced plating time. MAKE-UP: ZINNI AC AF 211 Basic solution: 10 ml/l (5-15 ml/l) ZINNI AC AF 212 Brightener: 20 ml/l (10-25 ml/l) ZINNI AC AF 213 Buffer: 30 g/l (25-35 g/l) ZINNI AC AF 214 Wetting agent 20 ml/l (10-25 ml/l) J. Unger Rev /5

2 BATH COMPOSITION AND OPERATING INSTRUCTIONS: RACK PLATING BATH Recommended bath composition Zinc chloride 40 g/l g/l Nickel chloride x 6 H 2 O 120 g/l g/l Potassium chloride 200 g/l g/l Boric acid 20 g/l g/l Analysis values Zinc 20 g/l g/l Nickel 30 g/l g/l Chlorid 150 g/l g/l Zinc/Nickel ratio 1:1.6 1:1.4 1:1.8 Operating instructions Temperature 35 C C ph ph should be monitored and can be adjusted by addition of hydrochloric acid or potassium hydroxyde solution. Cathode current density A/dm² Anode current density < 3 A/dm² Anode current ratio Zn : Ni 4:1-8:1 Agitation cathode agitation is required Deposition rate at 3 A/dm² µm/min J. Unger Rev /5

3 BARREL PLATING BATH Recommended bath composition Zinc chloride 40 g/l g/l Nickel chloride x 6 H 2 O 120 g/l g/l Potassium chloride 200 g/l g/l Boric acid 20 g/l g/l Analysis values Zinc 20 g/l g/l Nickel 30 g/l g/l Chlorid 150 g/l g/l Zinc/Nickel ratio 1:1.6 1:1.4 1:1.8 Operating instructions Temperature 30 C C ph ph should be monitored and can be adjusted by addition of hydrochloric acid or potassium hydroxyde solution. Cathode current density A/dm² Anode current density < 1 A/dm² Anode current ratio Zn : Ni 4:1-8:1 Deposition rate at 1 A/dm² µm/min J. Unger Rev /5

4 EQUIPMENT: Tanks Steel - rubber or lined with an acid resistant plastic coating Agitation Rack plating: For still operation cathode agitation parallel to anodes is recommended (2-5 m/min). Additional circulation by pumping or air injection is possible. Filtration Continuous filtration is required. (5-20µm) Heating Titanium, enamel or glass Anodes Zinc and nickel high purity anodes should be used. In the event of a zinc increase in the solution, parts of the anode surface should be replaced by inert anodes. The anodes should be put in bags out of acid resistant material. During breaks the zinc anodes should be taken out. The anode/cathode surface relation should be aproximatly 4:1-8:1. MAKE-UP: Dissolve the required chemicals in warm water (50 % of bath volume). Fill up bath with cold water, adjust ph and add ZINNI AC AF additives in given order. To avoid rough coatings continuous filtration is required. For make up with techn. pure salts first add ZINNI AC AF 211 and AC AF 213 and make some dummy plating for 2 Ah/l. Then add Zinni AC AF 212 and AC AF 214. J. Unger Rev /5

5 PLATING PROCEDURE: Parts to be plated must go through a cleaning cycle, consisting of degreasing and pickling bath prior to plating at pre-determined current density. Plated parts should be rinsed, passivated and dried to increase corrosion resistance and make them touchproof. SAFETY PRECAUTIONS: See Material Safety Data Sheets GUARANTEE: Above instructions and recommendations are the result of intensive testing and shop experiences. They are for your information, only. Our guarantee extends to the continuous quality of our products as they leave our factory and not to their usage in the field, which is a factor beyond the control of a supplier. J. Unger Rev /5