[r7t3n5]

Hello, if anyone would like to provide information in regards to this issue I have I would very much appreciate it.

There is a well known procedure removing iron oxide deposits (rust) on steel fracture surfaces so that the surface can be analysed under scanning electron microscopy (SEM).  This is a sample cleaning procedure which does not disturb the fracture surface which contains fine surface features used to describe the type of failure which occured.  The process involves the use of a sodium cyanide electrolye.  I would like to replace the sodium cyanide electrolye with something that is not lethal as this is being used in a plant and safety is at a premium.  This is a small scale process, I would be doing it in a small ultrasonic parts cleaner.

The procedure is also known as cathodic cleaning and is described as follows:

The process is carried out in a small parts ultrasonic cleaner.  The fracture sample to be cleaned (steel fracture) is made the cathode, hydrogen bubbles generated on the fracture sample surface remove surface debris and deposits by mechanical removal.  The anode is inert (carbon or platinum) to prevent plating onto the fracture sample.  The elecrolyte is sodium cyanide, I would like to replace it with something that is safer yet still effective.  Of course there is a voltage between the cathode and anode as well.  I guess the key is that electrolyte not plate or interact with the cathode (fracture sample) and provide a vigorous output of hydrogen bubbles at the sample surface to knock free the dirt and oxide deposits from the fracture surface.  The process goes quickly, only about a min.  I have seen it in action and it works great, but unfortunately you have to deal with this nasty chemical.

Thanks in advance!

[Arkcon]

Cyanide solutions are typically used for precious metal plating, the cyanide complexes gold, silver and the platinum metals.  I don't know why it would have to be used for steel -- I don't know, offhand, of any iron, nickel or chromium cyanide complexes.  Maybe you'd like to try thiocyanate? Or ferrocyanide?  They're (fairly) non-toxic, and complex Fe well.  Perhaps you can research some mild acid electrocleaning process.

[r7t3n5]

Cyanide solutions are typically used for precious metal plating, the cyanide complexes gold, silver and the platinum metals.  I don't know why it would have to be used for steel -- I don't know, offhand, of any iron, nickel or chromium cyanide complexes.  Maybe you'd like to try thiocyanate? Or ferrocyanide?  They're (fairly) non-toxic, and complex Fe well.  Perhaps you can research some mild acid electrocleaning process.

Arkon, thanks for the info.  I am not sure, but I think sodium cyanide is used because it will not plate onto the specimen or chemically interact with it.  As an electrolyte, the sodium cyanide dissociates into a Na+ and CN- and these don't interect with the specimen.  Anyone who would like to add anything please feel free!

Thanks again!

[soori71]

Sorry if this is too dumb, but what about Pure plain de-ionized water, with few drops of acid to make it conducting....? Water being electrolyzed should give off hydrogen as you expect, but oxygen on the other electrode as well.