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removong rust with electricity question

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  • jnormanh
    replied
    Originally posted by cliffh View Post
    Actually the hydrogen is produced at the Cathode (Negative). I can't find anything on-line where someone has documented hydrogen embrittlement caused by low voltage, low current electrolysis cleaning. I don't think the hydrogen gets trapped against the steel like it does with electroplating. Also chrome plating uses an acidic solution and higher current. But that is just my guess and to be safe I don't to use my electrolysis tank to clean hardened steel parts.

    First off let's clear up the terminology. The (+) positive pole is the anode. The (-) negative is the cathode.

    Yes, hydrogen ION is generated at the (+) anode. I misstated that hydrogen ion is generate at the cathode - my error. It is ATOMIC hydrogen which is generated at the cathode, and that is what dissolves into the steel and causes HE. All that bubbling is hydrogen gas, which is being created one atom at a time. Many of those atoms combine to form H2 gas, which bubbles off, but some of the single atoms dissolve into the steel.

    Hydrogen is not "trapped against" the steel, it is dissolved into the steel.

    Nonetheless it is at the (-) cathode where electrolysis can cause HE. And that can happen at ANY DC voltage. Yes, it's slower at low voltage, but where folks are talking about multi-hour times, it can happen.

    The fact that you haven't found a reference on-line means only that you haven't looked far enough. Entire books have been written on the subject, and it is covered in every Military Specification and commercial specification regarding cathodic cleaning I have ever seen.
    Last edited by jnormanh; 07-28-2013, 08:24 AM.

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  • cliffh
    replied
    Originally posted by jnormanh View Post
    You are correct.
    Actually the hydrogen is produced at the Cathode (Negative). I can't find anything on-line where someone has documented hydrogen embrittlement caused by low voltage, low current electrolysis cleaning. I don't think the hydrogen gets trapped against the steel like it does with electroplating. Also chrome plating uses an acidic solution and higher current. But that is just my guess and to be safe I don't to use my electrolysis tank to clean hardened steel parts.

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  • jnormanh
    replied
    Originally posted by cliffh View Post
    Then the electrolysis cleaning tank should be OK since the positive lead is connected to the rebar and the negative to the part.
    You are correct.

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  • cliffh
    replied
    Then the electrolysis cleaning tank should be OK since the positive lead is connected to the rebar and the negative to the part.

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  • R1 3137
    replied
    thanks for the correction.

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  • jnormanh
    replied
    Originally posted by R1 3137 View Post
    From my research I agree the brittleness is cause by higher voltage or possibly very extended periods of time.
    The hydrogenation is reversed by simply allowing the pieces to sit/rest for a week or two. It is a layer of metal that has exchanged hydrogen atoms and given time it swaps them back naturally.

    What you say is not so. Voltage has little to do with hydrogen embrittlement. Anything which causes hydrogen ions to be generated at the surface can cause it, including acid pickling with no current at all, as can DC current process where the part is connected to the (+) side of the circuit.
    In the case of steel parts, it is generally accepted that HE is not a problem with soft steel, ie those with a hardness below 30 Rockwell C. Basically that means that steel parts which have been stamped or machined to shape will not be affected unless they have been heat treated to harden them

    So a plain stamping, like a body part or door hinge is okay, but a conrod, crank, kingpin or steering arm, gear or roll pin, high strength fastener or any other steel part which has been heat treated can be embrittled and subsequently suddenly fracture under modest load.

    And NO, hydrogen embrittlement does not, EVER, just go away. It can be removed if the part is baked at 350 degrees for several hours, starting within one hour after the process. After that the steel microstructure is permanently altered, and subject to catastrophic failure at any time.

    The advise you gave is not just wrong, it is dangerous. Someone who believed you could potentially have, say a steering failure at high speed.

    What sort of "research" you have done, I do not know. Certainly not the scientific kind.

    Facts are easy to obtain. I strongly recommend you consider that before offering advise which is both wrong and dangerous.

    http://en.wikipedia.org/wiki/Hydrogen_embrittlement
    Last edited by jnormanh; 07-25-2013, 11:04 AM.

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  • wittsend
    replied
    I've heard of hydrogen embitterment when using acid (like muriatic acid), but am unfamiliar with this process and potential issues. Are they similar?

    Hey, I guess if you reverse the polarity you could "Rat Rod" even new parts.

    Tom
    Last edited by wittsend; 07-25-2013, 04:51 PM.

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  • R1 3137
    replied
    Originally posted by mmagic View Post
    I can understand suspension/electrolysis issues in a high voltage plating shop. I'm personally skeptical if it is a real issue in a 12 volt backyard solution that you can stick your hand in with voltage on for parts that are only in it for 8 to 12 hours. I'll continue doing everything that has rust.
    From my research I agree the brittleness is cause by higher voltage or possibly very extended periods of time.
    The hydrogenation is reversed by simply allowing the pieces to sit/rest for a week or two. It is a layer of metal that has exchanged hydrogen atoms and given time it swaps them back naturally.

    For small parts like nuts and bolts I'm going to use a parts basket in molasses from now on. I get tired of the wrapping, threading and aligning them in the tie wire. I'm thinking of trying a current through the molasses passing over/around the part as opposed to through the part just to see if there is a difference. Maybe a test is coming soon, I just need to find 3 or 4 equally rusty objects of the same size shape and metal.

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  • mmagic
    replied
    I can understand suspension/electrolysis issues in a high voltage plating shop. I'm personally skeptical if it is a real issue in a 12 volt backyard solution that you can stick your hand in with voltage on for parts that are only in it for 8 to 12 hours. I'll continue doing everything that has rust.

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  • doug
    replied
    Thanks for the information guys.

    It was mentioned not to do suspension parts because it makes parts brittle.. Does this mean brake drums and such are a no-no?

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  • Spannerbird
    replied
    That reminds me, I have to buy some penetrating oil (WD-40 most likely) to spray on a very worn 15mm nut to get the rear bumper guard off. Yes I was also wondering why a 15mm spanner fit it and not 5/8, but that'll soon change, just need to get it off so I can dump it in the electro tank, then send it or localise it for replating. That is if the surface isn't too pitted, but then I'll probably have to buy some surface prep.

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  • R1 3137
    replied
    I have used the same batch for a year no problems.I also just tried a batch of mollases mixed 1:9 with H2O on some wheels in a garbage can forS&G's and am very pleased with the results. I think the RE lifts old paint a bit better but they both leave original paint that is solid. The molasses worked great on the rusty stuff though. If line of sight is a issue getting a part done mollases is the answer for me from now on. Just watch for trapped air bubbles.

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  • mmagic
    replied
    I start with a roll of form tie wire to suspend parts in the barrel... cheap at HD, strong and easily ties small parts that so that even bolts can be suspended in the tank. And,.... disposable.
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  • Spannerbird
    replied
    I rarely dump my smaller container, which mmagic saw. But I do run a wire brush just as he does to make sure the rebar doesn't get too coated with rust.

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  • mmagic
    replied
    Solution gets murky quick. I've read several places that it doesn't wear out. I currently have done most of the parts removed from the Speedster and it is down to shell and frame today. The barrel has more than an inch of settling in the bottom and parts still come clean in 8 to 12 hours.

    After every other batch I run a wire brush down the rebar as loss of conductivity at this point is the first degradation in the process that I see.

    Before .... After... and with a 1 coat of Master Series.
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    Last edited by mmagic; 07-25-2013, 06:53 AM.

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