Troubleshooting Acidzinc

Acid Zinc 99R - Acid Zinc 100R

น้ำยาชุบซิงค์กรดแอมโมเนีย 99R - น้ำยาชุบซิงค์กรดโพแทสเซียม 100R

Acid Zinc Ammonium 99

The Acid Zinc Ammonium 99 system is designed for zinc plating with ammonium chloride. It ensures that the plated parts have high ductility and better zinc adhesion, especially in low-current areas. This system can be used for both rack and barrel plating. Additional advantages include high gloss of the plated parts, cost efficiency in operation, and special properties not found in conventional rack and barrel plating processes. In addition to providing a glossy zinc coating, the Acid Zinc 99 process offers the following key features:

Key Features:

1. Ease of Dissolution: The base and gloss agents of the 99 system dissolve easily in the plating solution without needing a solvent for dissolving gloss agents. This special property of 99 eliminates issues with gloss agent degradation at high temperatures, where gloss agents can easily decompose and turn into oil, resulting in loss of gloss agent.

2. Easy Washing: The plating solution allows for easy washing of parts, which helps in the long-lasting adhesion of chromate coatings and maintains high gloss.

3. Suitable for Various Materials: It facilitates plating on thin sheet metals, zinc die-cast, hot-rolled steel, and carburized steel effectively.

4. Versatile Current Range: The system can operate well under both high and low current conditions with high recess penetration.

5. Heat Resistance: Designed to continue functioning even with heat generated in the bath due to prolonged continuous plating, without affecting the parts.

Usage Instructions:

• Base Agent (ACIDZINC 99 M): 40 cc/L (rack), 35 cc/L (barrel)

• Gloss Agent (ACIDZINC 99 R): 0.4 - 0.6 cc/L (both rack and barrel)

Operational Conditions:

• Positive Current Density: 0.1 - 5 A/dm²

• Negative Current Density: 1 - 3 A/dm²

• Voltage (rack): 1 Volt

• Voltage (barrel): 4 - 9 Volts

• Solution Filtering: Should be filtered continuously, at least twice per hour

• Agitation: Recommended to use air agitation

• Air Blowing: Should be continuous

• Anode Material: Pure zinc plates 99.99%

• Temperature: 20-45°C

• pH of Solution: 5.0 - 5.6

Solution Ratios:

• Zinc Metal: 28 - 32 g/L (rack), 24 - 28 g/L (barrel)

• Chloride: 130 - 140 g/L (rack), 120 - 135 g/L (barrel)

New Solution Mixing:

• Zinc Chloride: 59 - 67 g/L (rack), 50 - 59 g/L (barrel)

• Ammonium Chloride: 150 - 160 g/L (rack), 142 - 158 g/L (barrel)

• Base Agent: 40 cc/L (rack), 35 cc/L (barrel)

• Gloss Agent: 0.5 cc/L (both rack and barrel)

Adjusting Additives:

• For every 1,000 ampere-hours, add:

  • Base Agent: 100 - 200 cc/L

  • Gloss Agent: 100 - 150 cc/L

Solution Component Management:

Maintain recommended levels for optimal results. Analyze zinc concentration weekly and add as needed. Chloride concentration should be analyzed and adjusted daily. Both base and gloss agents are consumed during plating; add based on Hull-cell tests.

Operational Checks:

• pH: Ideal value is 5.2; check and adjust daily

• Temperature: Optimal range is 20 - 45°C

• Current Density: Recommended range for barrel plating is 0.2 to 1.5 A/dm²

Plating Bath Recommendations:

• Use acid-resistant tanks such as polypropylene or polyethylene for chloride zinc plating.

Filtration:

Continuous filtration is necessary for both rolling and hanging tanks to remove iron contamination.

Troubleshooting Common Issues:

1. Blistering in High Current Areas:

   • Reduce current density

   • Increase base agent by 1% (10 cc/L)

   • Adjust zinc chloride concentration to 25 - 35 g/L

   • Ensure even agitation and air blowing

   • Reduce chloride concentration if too high

   • Increase solution temperature if too low

   • Adjust boric acid if using potassium chloride zinc

   • Check and clean anode connections

2. Dull Zinc Coating in Medium and Low Current Areas:

   • Increase gloss agent based on Hull cell tests

   • Lower solution temperature if too high

   • Adjust chloride concentration

   • Remove excess chloride or add water

   • Address contamination with heavy metals or tin

   • Balance base and gloss agents

3. Pitting or Irregular Coating:

   • Reduce gloss agent concentration

   • Adjust chloride levels

   • Lower solution temperature

   • Address contamination with iron or copper

   • Check and replace worn-out solution

4. Uneven or Poor Adhesion:

   • Remove chromium contamination

   • Balance gloss and base agents

   • Address organic compound contamination

   • Adjust chloride levels

   • Correct pH levels

5. Slow Plating Speed:

   • Increase chloride concentration

   • Optimize anode area

   • Adjust current density

   • Check power supply consistency

   • Correct low pH levels

6. White Residue on Parts:

   • Ensure thorough rinsing and reduce drying time before washing

   • Ensure chromate solution is not degraded

   • Acidify parts before plating if needed

7. Rough or Irregular Surface:

   • Remove excess zinc plates or clean filters

   • Replace damaged filters or adjust air blowing

   • Address metal contamination

8. Excessive Gloss Agent Consumption:

   • Lower bath temperature

   • Adjust gloss agent and base agent balance

   • Check and correct solution analysis

Iron Removal:

Iron can accumulate in the solution due to the acidic nature. To remove iron, use potassium permanganate (KMnO4) as follows:

• Usage: 120 - 150 g per 1000 L of solution

• Dissolve outside the tank and then add to the bath. Agitate for 15 - 30 minutes or bubble air through, then let settle overnight before filtering out the iron.

Checking Iron Content:

Take 100–200 cc of the solution, add a few drops of hydrogen peroxide or potassium permanganate, and check for iron precipitate. If significant, follow the above procedure for removal.

Note: Potassium permanganate may also reduce the concentrations of base and gloss agents, so adjustments may be needed.