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Tin growths on tin anodes
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I am working in a company which makes tinplate used for packaging.the line is an electroplating line with tin being the anode and the strip the cathode. My question here is we face a lot of problem regarding tin growths on the tin anodes which is loosely hanging on the anode and generally falls into the sink rolls and cause defects. I would like to have some sincere advice from you to get rid of this problem. What could be the factors responsible for such a thing to happen?
Ronen- Jamshedpur, Jharkhand, India
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Hi, Ronen. I would be surprised if these were growths unless there is something in your process that you didn't tell us. I think they are spikes and dendrites left from dissolution of the anodes and that you probably need anode bags to contain them. Good luck.
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You haven't given many details about the solution; - is it acid or alkaline? Furthermore, tin will not deposit onto an anode, so you will not get growths. However, you may be getting uneven dissolution of the tin from the anode, causing a roughness of the anode. This could cause the "growth" appearance you see. What is the purity of the tin anode? If it is impure, you may be getting insoluble bits left on the anode that ultimately fall off when all the good tin has dissolved. If it is an alkaline tin are you sure the anode has got a film on it to prevent the the stannite/stannate problem. If this is out of balance, you may well get a rough deposit on the cathode. Please give further details of your system.
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Trevor Crichton R&D practical scientist The Pheasantries - Chesham, U.K. |