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Author: Subject: Lead dioxide anode on less common substrates
Neme
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[*] posted on 12-7-2018 at 11:51
Lead dioxide anode on less common substrates


With vision of better substrate for lead dioxide anode, as graphite nor titanium are ideal, I have been searching for more exotic substrates. However I struggle to find nearly any usefull article. Initially I had an idea of tungsten or molybdenum substrate as they are readily accesible.

So I'm asking if any of you have experiences with uncommon substrates and if I should stick to graphite/titanium instead of trying other substrates.
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phlogiston
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[*] posted on 12-7-2018 at 13:16


No actual experience, but I recall niobium and tantalum being mentioned in the literature on this topic. I'm sure it shouldn't be hard to find more information on those.

I doubt they offer many advantages though, given that they seem to be not commonly used (if at all?).




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Heptylene
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[*] posted on 13-7-2018 at 13:31


What is the problem with graphite? Titanium passivates, which is a problem, but graphite doesn't. Plus graphite is cheap, available in thin plates and is unreactive.
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[*] posted on 13-7-2018 at 14:07


They don't know and you'll never know. 10 years ago I was hoping that at least here I will find a solution, and nothing. Nobody ever discovered what is problem. Of course, problem is that graphite erodes, somewhat too fast. And that is not problem in most cases, because it's cheap and can be replaced periodically.

But really why graphite erodes? Is it something chemical, electric or physical? Is it because of O or Cl only? Is it because graphite is soft anyway and physical disturbances (micro balloon explosions) cause it to erode? Or some compound appears at surface that reacts?

Nobody, not even NurdRage ever discovered and solved that problem. Nothing will be discovered for next 10 years. Except If I don't take things into my own hands, under my control. Talking is not enough. Most people are just talkers. I mean few tries would solve that mistery.

Graphite is good at cathode, 100% resistant. I mean, we can already conclude that electric current or gas balloons explosions are not the cause. It must be something with Cl or O? Actually I believe cathode is not resistant if high enough electric current is made. It should produce methane instead of H.

One problem is graphite's mechanical weakness and electric resistance and lot more.

[Edited on 13-7-2018 by AlexC]
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Heptylene
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[*] posted on 13-7-2018 at 14:29


@AlexC are you talking about plain graphite anodes or lead dioxide anodes on a graphite substrate? AFAIK only plain graphite anodes have erosion problem, I never heard about lead dioxide on graphite substrate having that problem.
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[*] posted on 17-7-2018 at 16:40


There are a few people who have tried to make anodes using PVC as the substrate. Firstly they dipped it he plastic in MEK or acetone to soften it and it is then dipped into Lead dioxide powder to cover as much as possible and then it is plated in a final coating of lead dioxide. Another attempt was done using Lead dioxide and an epoxy resin thoroughly mixed and shaped into a bar which was also finished with another coating of PbO2. Not sure about how well they held up though. The idea sounds good in theory but a perchlorate cell is pretty hard on the anodes so they may fail or they may work well.



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[*] posted on 17-7-2018 at 16:53


What is problem with this? I thought that Pb will not have problems like Mn. Weren't PbO2 anodes always doing it's job in car batteries? Are you not aware that using anything but metals will give you bigger electric resistance? We don't want that.

Are you saying that problem is with PbO2 not adhering to common metals? Just like MnO2? Or that it is flaking as NurdRage said?

But if it is found in car battery, it means it is doing well there. So why not use Pb electrode? I mean not whole electrode has to be Pb, but maybe some conductive cheap common metal coated with Pb then with PbO2? Is this good solution?
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