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plastic bin for alodyneing the center ribs

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  • #16
    I found that article a bit confusing. Is alodine an aluminum oxide coating ? It claims the coating is highly conductive...... Alo2 is a huge electrical insulator. It said the coating is soft. AlO2 is all most as hard as diamond. Have to do some more reading. Maybe the article I read on fatigue life reduction was for Andoising..... If I can find a good article I will pass it along-----
    Tim

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    • rcraddock
      rcraddock commented
      Editing a comment
      Caveat: It’s been several decades since my chemistry degree, but I think you’re blending anodizing which is electrochemical and does produce a hardened surface that can be undesirable for thin sheet metal with the alodine process which is at it’s core a chromic acid etch that deposits a soft chromium compound on the surface. Alodine doesn’t harden the surface and in fact can be removed with overzealous scrubbing with Scotchbrite. Aluminum passivates almost instantly any time it is cleaned and the resulting aluminum oxide surface comes from reaction with the air around us leaving a surface that is non-fabulous for paint adhesion. The chromium solutions take care of the aluminum’s demand for reacting and leave a “tail” sticking out that is very suitable for wetting and bonding with modern paint coatings. The obvious downside is that chromium compounds are very toxic but it is the “gold standard “ (pun intended) for corrosion protection. If you choose to use it please dry out the solution with very low heat, driving off the water and then dispose of the dry salts in a proper hazmat facility. It’s very bad for children and other living things.
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