Heat Treat Coolness

In yet another example of “Why Jessica’s Job is Cool”, I thought I’d share something that recently caught me eye on a supplier visit.

The particular location was a heat treater. I had never visited one before so I found the site interesting with its ginormous flame-spurting ovens and quenching vats. However, a rather small piece of equipment caught my interest. Through an opening less than a foot square, there was red glowing and bubbling goo.



A co-worker identified it as molten cyanide salt. We do not use this particular technique for our parts but it’s just fantastic looking isn’t it? Also, note the sign in the background “NOTICE: Do Not Add Water”. In addition to being highly toxic, cyanide salts are reactive with water. Both are reasons it’s not commonly done.

There don’t appear to be many sources of information about this technique on-line except for salt-bath equipment dealers and a whole bunch of warnings say “TOXIC: DO NOT DO”. I did however find this excerpt from the 1926 Machinist’s Handbook. They have 1 whole paragraph on this form of heat treating.