|Titanium||This is a good Cathode material if you can get it. It won't corrode and contaminate the product. The metal and it's hydrides have electro catalytic effect similar to Mild Steel for the evolution of Hydrogen. It also has the advantage of not reducing Chlorate. It lasts about 2 years in commercial cells with Hydrogen embrittlement ending its life. Use Grade 1, 2, 3 or 4. The Grades containing Al are inclined to warp especially at high temperatures. There are reports of thin sheets of Grade one Ti becoming brittle and breaking soon after they are installed in a cell. Use sheets that are at least 1mm thick.|
|Stainless steel||There are many types of stainless steel.|
Food grade works good, some of the other grades will corrode a small amount and give your solution a yellow colour. The yellow colour is colloidal Iron and Chromium. The Chromium is bad news when you are using a Lead Dioxide anode as it forms a thin layer on the Anode and drastically reduces the current efficiency. Use a grade that will not corrode at all. Protect exposed surfaces of the SS at the top of the electrolyte using plastic or such like. Don't leave the cathodes in the electrolyte with the power switched off.
Grades of SS that are OK are type 347, 316 and food grade SS.
Other alloys that are OK are Durimet 20, Hastelloy HB-1, Hastelloy HC-3, Hastelloy C. Don't leave in a cell that is not operational.
|Mild steel||This is cheap but it will corrode if you don't have Chromate in the electrolyte to help protect it. You can't use chromate's if you are using Lead Dioxide anodes and as Chromate's will lower current efficiency. Some of the Cathode will have to come up above the solution level so as to get a connection to it. This part should be protected with a plastic sleeve or something similar to stop it corroding in all cells Chromate's or not. The corrosion products are not detrimental to the Chlorate product but you may have a yellow colour (colloidal Iron) that need extra work to get rid of. You must not leave the steel in the cell if it is turned off or it will corrode even more. According to JES Vol.105. No.3 (1958) [bottom of last page] using mild steel drastically reduces current efficiency?. It has been used in industry.|
|Copper||Copper is OK if you are going to use your Chlorate for bleaching! For all other uses of Chlorate it should be ruled out completely.|
|Nickel||Nickel can be used as a cathode if you can get it but it will corrode if
you don't have Chromate's in the electrolyte for to protect it. It leaves a black mess in the Chlorate cell. It has been
used in Perchlorate production. You can't use Chromate's with Lead Dioxide
as the current efficiency will be low. You may be able to get Nickel
welding rods as a free sample from your welding supply store. In a report from a home producer of Perchlorate,
Nickel welding rods when used in a cell that went all
the way from Chloride to Perchlorate suffered corrosion. |
Don't leave in a cell that is not operational. Since it is a transition metal, it's ions will help to reduce Hypochlorite in the solution bulk of a Chlorate cell which is undesirable.
|Graphite||Graphite can be used for a Cathode but will blacken your product a small amount in the long run. Leaving them sitting in a cell when it is turned off causes it to corrode somewhat and they shred a bit when the current is turned back on. They make good cathodes if you take them out of the cell when they are not in use and give them a wash. They are a good choice for the Amateur as they will not contaminate your cell with Chromate's if you are using a Lead Dioxide anode. Graphite rods are available as gouging rods from the welding supply store. Remove the copper coating (if they have any) by peeling. Then run in a small cell for a short period and dump contents. This gets rid of all Copper that may have been on the rods after peeling.|
|Lead metal||Lead has never been used in industrial setup's but would make an easily fabricated Cathode|
|Lead dioxide||Lead dioxide should NEVER be used as a Cathode as it will dissolve in a short space of time|
|Platinum||You can use Platinum as a Cathode of you so wish.|
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