Troubleshooting Black Nickel

Troubleshooting for Black Nickel Plating Solution

1. Problem: Burned Appearance on Plated Surface

   • 1.1: Excessive current. Reduce the current.

   • 1.2: Temperature too high. Lower the temperature to 50°C.

   • 1.3: Insufficient black nickel salt. Add 5-10 grams/liter of black nickel salt.

   • 1.4: pH too high. Lower the pH with hydrochloric acid.

2. Problem: Brown Color on Plated Surface

   • 2.1: Excessive current. Reduce the current.

   • 2.2: Temperature too high. Lower the temperature to 50°C.

   • 2.3: pH too low. Increase pH with 50% caustic soda.

   • 2.4: High drying temperature. Lower the drying temperature.

3. Problem: Blue or Rainbow Color on Plated Surface

   • 3.1: Insufficient current. Increase the current.

   • 3.2: Insufficient black nickel salt. Add more black nickel salt.

   • 3.3: pH too high. Lower the pH with hydrochloric acid.

   • 3.4: Solution imbalance. Add 5-10 grams/liter of black nickel salt.

4. Problem: Peeling of the Plated Surface

   • 4.1: Poor surface preparation. Activate the surface with 5-20% sulfuric acid. For long-term nickel plating, extended activation may be necessary, or re-preparation may be required.

   • 4.2: Excessive current. Reduce the current.

   • 4.3: High drying temperature. Lower the drying temperature.

5. Problem: Inadequate or Spotty Plating

   • 5.1: Insufficient current. Increase the current.

   • 5.2: Insufficient black nickel salt. Add more black nickel salt.

   • 5.3: pH too high. Lower the pH with hydrochloric acid.

   • 5.4: Poor current distribution. Check the current flow paths.

   • 5.5: Clean the anode heads in rolling tanks regularly. The anode heads must be clean and free of adhered plating.

   • 5.6: Avoid using thick metal hooks in hanging tanks.

   • 5.7: Insufficient plating time. Increase the plating time.

Usage Instructions (Use distilled water for mixing)

• Black Nickel Salt: 120–150 grams/liter

• Solution Temperature: 30–50°C

• Solution pH: 5.2–5.8

• Anode: Nickel sheets or nickel pellets

• Current (Voltage): 1.0–2.0 Volts

• Current Density per Piece: 0.1–1.0 Amp/sq. dm

Recommendations

• For Brass or Copper Workpieces: You can directly plate with black nickel. For steel workpieces, plate with bright nickel first to provide a smooth base, resulting in a more uniform black nickel finish.

• Surface Preparation: Follow the same preparation steps as for bright nickel plating.

Adjusting the Solution

• Measure the solution concentration with a Bome (specific gravity) meter. Normal Bome value should be 9–10.

• Black nickel plating requires lower current, so it will take longer compared to bright nickel plating but will yield a deeper black finish.

  • Barrel Tanks: Use approximately 1-2V, for 40 minutes or more.

  • Racking Tanks: Use approximately 0.5-1V, for 5 minutes or more.

Note: Information may vary based on tank size, solution control, and operational conditions.