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Re: oxalic acid/ graphite

Paul Sears said:

Date: Thu, 28 Nov 2002 08:38:50 -0500 (EST)
From: Paul Sears <psears at nrn1_NRCan.gc.ca>
Subject: Re: oxalic acid/graphite

	I think I can guarantee that titanium will _not_ work.  The
titanium II and III electrode potentials are much worse than those
for iron.

- --
Paul Sears        Ottawa, Canada

I know I am late in responding to this thread and that I am only up to Nov. 
28 in reading my backlog of APD, but I wanted to respond to the titanium 
electrode issue. I am an electroplater for my occupation. We use titanium 
baskets to hold our anode materials, the metal that is being plated. The 
baskets do not corrode as long as they are full of the anode metal usually 
in the form of small disks of nickel, copper, zinc, etc. If the basket is 
not filled or a gap forms in the packing of the anodes into the basket, the 
titanium basket will dissolve in the bare area. Titanium is a very poor 
conductor of electricity by itself. The anodes are conducting the bulk of 
the current in the basket.

When plating Gold most anodes are Platinum or Niobium clad titanium mesh. 
The cladding provides the electrical conductivity. Over time the cladding 
will deteriate and the anode will need to be replaced. The gold is replaced 
in solution as Potassium Gold Cyanide salt. Modern gold solutions do not use 
gold anodes to replenish the gold in solution due to the high value of solid 
gold. It would tend to walk out of the plant!

As far as graphite electrodes go, they have a use as well. They are used to 
balance the anode area to maintain a constant metal concentration in certain 
plating baths. Plating suppliers will sell it. Try www.Finishing.com if you 
want to learn more about electroplating and to find links to suppliers.

Jerry Smith
Bloomingdale, NJ, USA

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