Heef 25 Hard Chrome Plating process

 HEEF 25 is a fluoride-free hard chromium process that offers high current efficiency. It can be adapted for various applications, including normal hard chromium plating, duplex hard chromium plating, and chromium plating of rotogravure cylinders. The process provides advantages such as excellent deposition efficiency, reduced rectifier electricity costs, and good deposit metal distribution. HEEF 25 is known for its bright, hard deposit with high resistance to abrasion. The process also results in a microcracked deposit that enhances corrosion resistance. Regular maintenance and adjustments are necessary to ensure optimal sulfuric acid content and chromic acid concentration in the bath.

To make up the HEEF® 25 - Liquid hard chromium plating bath, follow these steps:

1. Clean the tank thoroughly.
2. Fill the tank to 35% or 40% full with deionized water and heat it to the desired temperature of 55-65 °C.
3. Add the required amount of Chromic Acid Solution (500) while stirring thoroughly.
4. Add the required amount of HEEF® 25 M while stirring thoroughly.
5. Fill the tank to its operating level with deionized water.
6. Analyze the bath for sulfate concentration.
7. Carefully add sulfuric acid to achieve the desired concentration (3.5, 3.22, or 3.68 g/l) while stirring.
8. Place dummy cathodes into the tank and then add the anodes with current for about 4-6 hours at 40 A/dm² (not necessary for hard chromium plating of rotogravure cylinders).
9. Use a mist suppressant from the non-PFOS Fumetrol®  range to reduce spray mist and drag-out losses.
10. Conversions of conventional hard chromium bath to HEEF® 25 - Liquid should be done only after analysis AT ESS ESS TRADING LAB, Coimbatore. ( Contact 9843019701) Email: info@essesstrading.in)
11. Always observe all regulations regarding operations with chromic acid carefully.

Remember, the bath maintenance requires adding Chromic Acid Solution (500), HEEF® 25 A, sulfuric acid, and mist suppressants. Barium carbonate is used for sulfate precipitation in case of excess sulfate.

To make up 100 liters of the Hard Chromium Plating solution using the HEEF® 25 - Liquid process, the following components are required based on the information provided:

A. Conventional Hard Chromium Plating:

• Water fully demineralized: approximately 45 liters
• Chromic Acid Solution (500): 50 liters
• HEEF® 25 M: 5 liters
• Sulfuric acid, chemically pure: 0.19 kg or 190 ml

B. 2nd Step for Duplex Hard Chromium Plating:

• Water fully demineralized: approximately 37 liters
• Chromic Acid Solution (500): 58 liters
• HEEF® 25 M: 5 liters
• Sulfuric acid, chemically pure: 0.2 kg or 200 ml

C. Hard Chromium Plating of Rotogravure Cylinder:

• Water fully demineralized: approximately 37 liters
• Chromic Acid Solution (500): 58 liters
• HEEF® 25 M: 5 liters
• Sulfuric acid, chemically pure: 0.175 kg or 175 ml

These are the quantities needed to make up 100 liters of each type of hard chromium plating solution as per the provided information .

The working parameters for the HEEF® 25 - Liquid hard chromium process are as follows:

• Temperature:
  • Conventional and Duplex: 57 °C (55 - 65 °C)
  • Rotogravure cylinder: 60 °C (55 - 65 °C)
• pH: < 1, does not need to be monitored.
• Densities:
  • Conventional: approx. 1.18 g/cm³ (22 °Bé) at 20 °C
  • Duplex and Rotogravure cylinder: approx. 1.2 g/cm³ (24 °Bé) at 20 °C
• Current densities:
  • Cathodic: 50 A/dm² (30 - 70 A/dm²)
  • Anodic: 25 A/dm² (15 - 35 A/dm²) (about 50% of cathodic)
  • For Rotogravure cylinder, the cathodic and anodic current density depend on the plant in use.
• Current efficiency:
  • Approx. 25.0% at 50 A/dm²
  • Approx. 26.8% at 70 A/dm²
  • Approx. 27.7% at 90 A/dm²
• Rate of deposition:
• Approx. 1 μm/min at 55 A/dm²
• Rate of deposition may be lower when using rotogravure cylinders, depending on the depth of immersion.

  For the maintenance of the HEEF® 25 - Liquid hard chromium process, the following products and chemicals are necessary:

  1. Chromic Acid Solution (500) - Used to maintain the chromic acid concentration in the plating bath.
  2. HEEF® 25 A - A liquid additive containing special HEEF® 25 - Liquid additives, without chromic acid or sulfuric acid, added to maintain the normal amount of additives in the bath.
  3. Sulfuric acid, chemically pure - Used for additions to achieve the required sulfate content.
  4. Barium carbonate - Used for maintenance to precipitate sulfate in case of excess.
  5. Fumetrol® 21 range of mist-suppressants - Can be used for make-up and maintenance to reduce the bath's surface tension and meet local regulations regarding Chromium-VI compounds in the air .

  The Chromic Acid Solution (500) addition rate is typically 80 to 110 ml of HEEF® 25 A per 1000 ml of Chromic Acid Solution (500) depending on the plating operation and parameters used.

  The nominal values for Conventional Hard Chromium Plating (Make-Up A) are as follows:

  • Chromic acid (CrO3): approx. 260 g/l during make-up, 235 – 270 g/l during operation.
  • Chromium-III (Cr3+): < 8 g/l.
  • Sulfuric acid, Chemically Pure (1.84 g/cm³): 3.5 g/l (1.9 ml/l) during make-up, 3.2 – 4.5 g/l (1.74 – 2.45 ml/l) during operation.
  • Chloride (contamination): < 50 mg/l.
  • Total Foreign metals (Cu, Fe, etc.): < 18 g/l
  • The current density for the conventional and duplex hard chromium processes ranges from 30 to 70 A/dm² for cathodic and 15 to 35 A/dm² for anodic. Specifically, the cathodic current density is recommended at 50 A/dm², whereas the anodic current density should be around 50% of the cathodic current density, which would be 25 A/dm². For the rotogravure cylinder process, the cathodic and anodic current densities are dependent on the specific plant in use.

The deposition rate and current efficiency for the HEEF® 25 - Liquid plating process are as follows:

• Deposition Rate:

  • At 40 A/dm²: 43.3 μm/hour
  • At 50 A/dm²: 57.7 μm/hour
  • At 60 A/dm²: 72.2 μm/hour
  • At 70 A/dm²: 86.5 μm/hour
  • At 80 A/dm²: 100.7 μm/hour
  • At 90 A/dm²: 115.0 μm/hour
  • At 100 A/dm²: 129.9 μm/hour (Page 11)

• Current Efficiency:

  • At 40 A/dm²: 23.5%
  • At 50 A/dm²: 25.0%
  • At 60 A/dm²: 26.0%
  • At 70 A/dm²: 26.8%
  • At 80 A/dm²: 27.3%
  • At 90 A/dm²: 27.7%
  • At 100 A/dm²: 28.1% 

Additionally, it is mentioned that the bath temperature should be adjusted respective to the current density, for example, 55°C for 40 A/dm² to 65°C for 100 A/dm² 

To buy this product please contact us 

at 9843019701 or Email info@essesstrading.in