Zincate Replacement

Ask an Expert From: Products Finishing, ,

Posted on: 2/1/2005

Question: We are required to plate a large number of aluminum parts.

Question:

We are required to plate a large number of aluminum parts. Are there any other ways to prepare the aluminum for plating that do not involve the zincating process? K. J.

Answer:

Yes, there are alternatives to the classic zincating process used for preparing aluminum for plating. Two such processes are as follows:

 

  1. Remove grease and oil using a suitable cleaner.
  2. Alkaline clean.
  3. Rinse thoroughly.
  4. Acid dip for 25–35 seconds using a 30% nitric acid and 30 g/liter ammo- nium bifluoride solution.
  5. Rinse thoroughly.
  6. Immerse for 30 seconds in an alkaline stannate solution (sodium or potassium stannate and sodium or potassium hydroxide with proprietary additives).
  7. Strike in a bronze plating bath (propri- etary bath).
  8. Rinse well.
  9. Plate in desired plating bath.

 

The second process is an anodizing process:

 

  1. Clean parts thoroughly.
  2. Thoroughly rinse.
  3. Dip in nitric acid.
  4. Thoroughly rinse
  5. Anodize in a phosphoric acid solution (20–60% phosphoric acid, 80–95°F, 5–30 volts, 5–15 minutes).
  6. Thoroughly rinse.
  7. Plate in desired plating bath.

 

As can be seen both of these processes are not necessarily any less complicated than the zincating process and hence are not seen that often in plating operations. In addition, the first process uses proprietary materials that may or may not still be available.

The bottom line on this is that unless your customer requires a process without zinc, stay with the zincating process.

 


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