The authoritative public forum
  for Metal Finishing since 1989
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Uses of HF in Metal Finishing

2000

I am researching the uses of HF in metal finishing. I have found the following (what I believe are relatively common) uses: pickling stainless steel, desmutting high silicon aluminum alloys and die castings, and etching aluminum, titanium and beryllium

• 1) Are there additional uses of HF that I have overlooked?
• 2) Has anyone had success with diffusion dialysis to reuse the HF in any of these process baths?
• 3) Are there practical alternatives to HF for any of these uses?

Thanks. Karen Thomas Pollution Prevention Consultant

Karen Thomas
- Boston, Massachusetts

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Hello.

We use HF for both pickling of stainless steels and for a bright-dip/descaler of a silicon-iron bronze. This bronze is used to manufacture aerospace bearing cages which we then silver plate.

I am curious as to what motivates your study? Simply put, we have found no substitute for HF when there is silica in the metal you are working with. We do often use sodium fluoride salts in an acid solution instead of strait HF for safety reasons and rarely see a problem.

Mike wells
- jamestown, New York
2000

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Hello, Karen!
HF is used in EN plating on magnesium for activation because magnesium fluoride can be deposited on the surface and give protection. Someone uses NH4HF2 to replace HF but has found it not very successful. Hope you can find a better alternative.

Yanghui Xiang
- Shanghai, China
2000

Help me on things about stainless steel.

Muhammed Patel
- Gloucester
2001