The authoritative public forum
  for Metal Finishing since 1989
-----

Coating to prevent corrosion on hastelloy

2005

Is there a special treatment to prevent corrosion by sulfuric acid on a hastelloy probe?
Just a remark: This treatment or finishing, must not be anything that hardens, for there are flexible parts on the probe.

Thanks,

Diego Foltz Hanser
Industrial Equipments - Sertaozinho, Sao Paulo, Brazil

Depending on the type of Hastelloy (you forgot to say) there might be options, but in general, this family of alloys are as corrosion resistant as can be any conventional coating. If plastics are out of the question I doubt you will find anything adecuate. Probably gold or platinum will prove somewhat effective but expensive.

Guillermo Marrufo
Monterrey, NL, Mexico
2005

---

2005

There is a "pickling" process for nickel alloys which is supposed to remove iron particles that may have been imbedded during the manufacturing processes.

1% Wt. HCl (20 Be)
1% Wt. ferric chloride ⇦this on eBay or Amazon [affil links]
Water

Ambient temp.
Time is < 1hr.
Check result by immersion in 1% lab grade sodium chloride for 12-24 hrs. No red rust=success.

Bill Grayson
- San Jose

---

I use to coat the pressure sensors like the photo ones with two materials:
- PTFE also known as Teflon from DuPont (50 micrometers =2 mils)
- ECTFE known as HALAR from Solvay (300 microns = 12 mils)

The thickness of the coating is critical as you are coating a membrane.

Jordi Pujol
- Spain
2005