I apologize for an off-topic... topic, but I've seen many threads about corrosion on coin/medal/token metals. I figure a bunch of smart and friendly people like you may have an answer for me:


What is a quick and efficient way to corrode steel?


The context: I need to remove steel that is casing some NiTi alloys without damaging the alloys (expensive stuff).

Thanks for any help at all and I'll keep my future threads strictly coin-related!

George

Strickly speaking you would need to look at corrosion rates for the composition of NiTi you have
I started life as a corrosion engineer and the bane of those highly cost mixes is interstice, intregranular, pit corrosion ( one hole through your expensive pipe in one place without loss of thickness anywhere else )
Especially chlorine compounds will damage expensive stainless steel
I guess concentrated sulphuric acid may be safe or nitric acid a little bit more daring

This being said I would look up the corrosion rates ( ask Uddeholm cause when I finished Univ they gave me a free corrosion speed book which is out of date now if I could find it back )

http://www.uddeholm.com/

Thanks, Ageka.

I'm at Univ. to be a materials engineer (hence the NiTi) but I've never been great at electrochem. I'll check out that link and will heed your other advice.

Well if you have access to a safe fume exhaust and activated carbon full face protection equipment and if you have access to exotic chemicals then reverse eletrolysis would be the fastest
Except after all these years I could not even start to tell you what chemical to use between anode and kathode nor the material to use against the iron outside

I once at to electro coat a few microns of bronze on steel keeping the same % compositon of the deposited bronze as the original bronze and that only worked with heated concentrated sodium cyanate and like 24 volt batteries (1 liter of cyanate probably enough to kill a 100 people )

The deadly chemicals are considered a no-no. The current apparatus in place before I joined the group took about a week and did a good job of removing most of the steel. The remaining steel could be sanded off easily. However, that process is great for the non-porous NiTi. Some members of the group have much more porous, large grained NiTi that is attacked by this process much more readily.

Today has been non-stop busy for me. I'll check on some of the stuff you mentioned tonight in between homework problems and a bajillion other things.

As to why this reply even exists... I consider it part of my down-time.