RC-290 Acidic Zinc Electroplating Process

INTRODUCTION

It is a bright coating which can be operated in a wide range of current density (including barrel and rack plating); applied for acidic zinc plating baths containing ammonium based and non-ammonium based.

• Excellent leveling;

• Excellent brightness can also be achieved at different potentials;

• Excellent ductility of the coating;

• It is suitable for different substrates, including cast iron and carbon steel;

• The coating is easily passivated; excellent depth-plating performance;

• Suitable for both barrel and rack plating, high cloud point.

EQUIPMENT

Anode: pure zinc (minimum content 99.99%), both zinc plate and zinc ball can be used (using titanium metal anode basket load). If zinc balls are used, please remember to add the anode in due course, and in order to avoid the electrolysis of the titanium metal basket caused by insufficient anode zinc balls, it is advisable to use a protective coating in the position where the electroplating solution is exposed.

Anode bag: nylon, PP, and other acid-resistant materials are recommended for rack plating to prevent rough coating of surfaces.

Tank: steel (rubber seal), PVC/PE/polypropylene (do not use glass fiber).

Temperature control: both heating pipes and heat exchangers can be used. If titanium metal equipment is used, the heating pipe cannot be connected to the circuit to avoid electrical corrosion. PTFE, PTFE sealed copper tubes, graphite (carbon) tubes or quartz (silicon) can also be used. (Lead or steel tubes are not allowed)

Filtration: the bath needs to be continuously filtered, and the filter pump can filter the bath 2-3 times in 1 hour. Diatomite additives can be used if filtration additives are required.

Ventilation: required.

Rotational speed: 3-9 cycles per minute is recommended.

Agitation: air or mechanical stirring is required to prevent bubbles from forming on the coating surface. Air agitating consumption is about 10 cubic meters per square meter of tank per hour. (Recommended horizontal approach if cathode agitation is used)

Rectifier: available to supply 12 V DC with amplitude less than 5-7%.

FUNCTIONS OF COMPOSITION

Zinc chloride: It is the primary source of zinc ions at the beginning, which affects the deep plating performance and bright area. Zinc replenishment is controlled by anodic dissolution and by analysis. If the amount of bath drag-out is excessive, zinc chloride can be used to increase the zinc content.

Potassium chloride: It is the main source of chloride in a non-ammonium baths. Chloride is a current conductor whose role is to provide conductivity and depth-plating performance. The chloride ions content can be controlled by analytically, and potassium chloride is used to replenish the losses of drag-out.

Ammonium chloride: It is the source of chloride in an ammonium bath. Chloride is a current conductor whose role is to provide conductivity and deep plating performance. Ammonium chloride is used to replenish the losses of drag-out.

Boric acid: It is the source of boric acid ions at the beginning. It has a buffer action that stabilize pH and prevents burning. Its content can be controlled by analytically, and replenish the losses of drag-out by a continuous manner.

REPLENISHMENT AND MAINTENANCE

Note: the above numbers are intended only used as a reference, and the specific replenishment will be determined based on actual operating conditions and the workpiece.

MATTERS NEEDING ATTENTION

Excellent pre-treatment is one of the prerequisites for good adhesion of the zinc coating. In order to remove the serious dirt and grease from the workpiece, an alkaline cleaner is recommended. And acid leaching for corrosion or deposits on workpiece.

Electrolytic cleaning can be used independently of anode electrolytic cleaning or cathode electrolytic cleaning (Note: a minimum of two times the time for the anode electrolytic cleaning after the cathode electrolytic cleaning).

SOLUTION ANALYSIS

Chemical analysis of zinc content

--Reagents

High concentration of ammonia, density of 0.91;

Buffer solution: 55 g of ammonia chloride and 67 ml of high concentration ammonia water, diluted with pure water to 1 L.

Erichrome BlackT indicator;

0.1M EDTA solution.

--Steps

1．Pipette a 2 ml solution into a 250 ml Erlenmeyer flask, and add 50 ml of pure water.

2．Add 25 ml of buffer solution and a small amount of indicator, and the solution should be turned to light blue;

3．Tiitration with 0.1M EDTA solution until the color turns colorless or light gray from light blue end point. Please note that the color changes very quickly from titration to the final stage, slow down when approaching the end point.

Calculation: Y is the amount of EDTA solution (unit = ml)

Y x 3.3 = zinc content (unit = g/l)

Chemical analysis of chloride ion content

--Reagents

2% sodium chromate indicator;

0.1M silver nitrate solution.

--Steps

1．Pipette a 0.5 ml solution into a 250 ml Erlenmeyer flask, and add 50 ml of pure water;

2．Add 1 ml sodium chromate indicator;

3．Titration with 0.1M silver nitrate solution until the white deposit turns brown, and the brown will not disappear due to shaking and mixing.

Calculation: Y is the amount of EDTA solution (unit = ml)

Y x 7.12 = chloride content (unit = g/l)

Chemical analysis of boric acid content

--Reagents

0.1N sodium hydroxide standard solution;

Indicator - 0.04 Bromcresol purple alcohol solution;

Mannitol;

--Steps

1．Pipette a 2 ml solution into a 300 ml Erlenmeyer flask;

2．Add 5 drops indicator;

3．Add a small amount of mannitol;

4．Titration with 0.1N sodium hydroxide solution until the sample turns blue.

Calculation: Boric acid content (g/l) = sodium hydroxide solution dosage (ml) x 3.10

SAFETY AND ENVIRONMENTAL

A Material Safety Data Sheet (MSDS) includes product safety instructions and environmental protection instructions. Read and review the MSDS for appropriate health and safety warning before use.

WARRANTY

1. We provide guarantee for product quality under the valid law.

2. The quality of the product after reprocessing or repackaging by customer is not included in the guarantee.

3. Please feel free to contact us if you have any questions or issues about the products, we are ready to answer at any time.

COLOR & PACKAGING

RC-290 is colorless liquid with plastic barrel packaging. The packaging specification is 25 kg/pcs.

RC-290 LCD Booster is bronzing liquid with plastic barrel packaging. The packaging specification is 25 kg/pcs.

RC-290 Replenisher is tawny liquid with plastic barrel packaging. The packaging specification is 25 kg/pcs.  

?IMPORTANT NOTICE REGARDING THIS INSTRUCTION BOOK

The product information and recommendations contained in this document are based on our experimental theory and data. Due to the particularity of the surface processing, further as the actual use of our products by others is beyond our control, NO GUARANTEE of any kind is made as to the effects of such use, and NO RESPONSIBLE for any consequences. Also, all the information in this document cannot be used as evidence of copyright infringement.