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Thread: Passivation or not?

  1. #11
    Join Date
    Nov 2009
    Posts
    1,418
    I am guessing that the steps are to media blast first, then passivate. Correct? Also, I am guessing the media blast is used to increase surface area. I dont have a media blaster. Would a good sand paper scrubbing achieve similar results, or is that a bad idea? So far, I have not done anything to the plates, they are smooth as glass...
    Tim, most do not have a sand blaster but find a powder coater and they usually do a good job of blasting. Make sure they understand if not done right the plates will get warped and ruined!!! Sanding with 8o girt sand paper in a cross hatch pattern is better than smooth. I think there is much more to media blasting than just increasing surface area and smaller bubbles releasing easier, just have not been able to explain it yet with good science. Your steps are correct because when you blast or sand you are removing some if not all of the existing passivation and if left alone it will not be even as it naturally passivates, making for an uneven performing plate. Using a controlled stripping of all the existing passivation and impurities and then controlling the process gives you a plate that is evenly passivated across the whole plate.
    "Democracy is two wolves and a lamb deciding what to have for dinner. Liberty is a well-armed lamb."

    ONE Liter per minute per 10 amps which just isn't possible Ha Ha .

  2. #12
    Join Date
    Oct 2009
    Posts
    333
    For those of you who are as cheap as I am, I found White Distilled Vinegar works well doing passivation. I usually do that after the cell is build, then I use the test run as the cleaning phase. The plates must be media blasted, this is process everyone should incorporate during their build.

  3. #13
    Join Date
    Aug 2011
    Location
    Hollywood FLA
    Posts
    53

    Disposing of acidic solution

    Any suggestions to properly dispose of this acidic solution after passivation. Is it safe to simply dilute with water and flush away? Citric acid does not sound too bad but if I am wrong please let me know. Wife would kill me if I melted her crapper or burnt her butt...

    I went with the sand paper approach for this build. I will look for a powder coater for a future build.

  4. #14
    Join Date
    Nov 2009
    Posts
    1,418
    Tim, remember critic acid is a food product. In a whole lot of things. So critic acid by itself is not a problem but what else is in your citric acid after using it to passivate the plates is unknown to me. Get it tested and let us know. I can say it will not melt your crapper. LOL What ever you do with it be responsible.
    "Democracy is two wolves and a lamb deciding what to have for dinner. Liberty is a well-armed lamb."

    ONE Liter per minute per 10 amps which just isn't possible Ha Ha .

  5. #15
    Join Date
    Aug 2011
    Location
    Hollywood FLA
    Posts
    53

    Passivation Final Test/Verification

    Well I completed the passivation process last night. So on with the build. I did not have the luxury of heating the solution so they simply soaked for two hours at room temp in solution. I followed all of the instructions so I presume all is good. From what I have read there is no real test to confirm the process was successful other than time will tell. If you know of any test, please let me know... Thanks a ton for all of your help and advice!

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