Egon, Why am I amused when you discuss nobility?
Actually, as per usual, you are pretty much on target.
I came up with a scheme a few years back to clean up and "passivate" stainless steel. My motivation was stainless steel in marine use (mostly yachts) where much of the bloody stuff rusts a bit. The idea was to reverse plate out of the surface the iron molecules leaving behind a concentration of the other components of the alloy such as chrome.
If you have ever seen the advertisements for plating outfits that use a brush-electrode to "paint"-plate metal objects without a submersion tank then you know where I got the idea.
For a simple demo of electroplating without an external power source just clean up your pocket knife blade real good getting off all the oils and fingerprints then dip it is coper sulphate solution for a while. Voila, your blade is now copper plated. Some of the copper in the copper sulphate was exchanged with iron molecules from the surface of the blade converting some of the copper sulphate to ferrous sulphate.
In the olden days when an American "copper" penny was actually copper and not just copper coated, you could use it as a source of copper to electroplate things with copper.
The post on derusting was quite timely as I recently discovered where two of my Ridgid brand pipe wrenches and a 9 pound sledge hammer were forgotten...under my mom's house and yes they are really rusted badly. We'll see what I can do with my little battery charger and some washing soda. I had planed on phosphoric acid (active ingredient of naval jelly) and a lot of wire wheel action but think I'll "trust the Force"... electromotive force that is.
I'll have to read more about the science behind the process as I am not comfortable with the authors POV on a couple issues. One of these is the overstated hydrogen hazard. I realize that there may be some liability shedding involved but it would take quite a lot of hydrogen gas and a fairly tight room to create an explosive atmosphere. Opening windows or doors would virtually elliminate the possibility of an explosion. I wouldn't suggest doing this in a small tight space.
One of the links to scientific discussion contained this phrase...
"The H+ formed is quickly neutralized by the carbonate to make carbon dioxide."
If this was confusing to anyone out there who may have wondered how hydrogen forms carbon dioxide, I suspect the author intended to use oxygen not hydrogen in his comment.
This will be a fun thing to try!
Pat /forums/images/graemlins/smile.gif
