Titanium vs Stainless Steel

Discussion in 'Materials' started by mojounwin, Nov 10, 2017.

  1. Angélique
    Joined: Feb 2009
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    Location: Belgium ⇄ The Netherlands

    Angélique aka Angel (only by name)

    Thanks for the answer Barry . . :)

    Presumed the guessed answer is right, then I understand from that, take a SS∙316 flat washer of a much larger diameter as the titanium flat washer on top of it, so the current density on the topside of the larger SS∙316 flat washer would be higher as on the other side which rests on the SS∙316 chain plate, which would make the smaller contact side on top of the larger SS∙316 flat washer sacrificial, is this a correct assumption . . ? ?

    P.S. - - Please see also my question in post #14.
     
    Last edited: Nov 13, 2017
  2. Barry
    Joined: Mar 2002
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    Barry Senior Member

    Re making the washer sacrificial
    The entire stainless chainplate will be anodic and corrode. The higher current density at the dissimilar metal washer interface will accentuate the corrosion in that area. I doubt that you can put a washer in place that will "force" only one part of the anode to be the sacrificial anode.

    Re how long does it take SS to become passive in oxygen re post 14.
    I could only find one reference and it said basically minutes. As I could not substantiate this with any other resource, I did not want to present this. Ie the one paper did not have
    the actual values or offer the chemical equations to substantiate the comment.

    In the early 70's, I was a co-owner in an electroplating company that deposited chromium from a proprietary flouridic based formula at high current density to resist corrosion, reduce friction and wear at thicknesses of about .0002" thick.

    In order to clean the material prior to plating, we degreased and then vapor honed the piece,( water, alum and a fine flour like abrasive in a water jet) to remove particles, then a wash and then into the acid tank.
    On some of plated materials, and memory does not serve me well here as to the material, ie stainless, brass, titanium , if the piece would dry, the piece would not accept the chrome deposition. We were told by the manufacturer of the process, that we had to keep the piece wet, and immerse the piece while it was wet, with current applied to the piece, then into the bath. They said that otherwise the piece would become passive. It did work, but terribly cumbersome.
     
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  3. Angélique
    Joined: Feb 2009
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    Location: Belgium ⇄ The Netherlands

    Angélique aka Angel (only by name)

    Thanks for all the info you posted Barry, I've learned a lot, and hope the OP had his questions answered too along the way . . :)

    Maybe he will tell us one day which of the bolts × chain plates options he has chosen.
     
    Last edited: Nov 16, 2017

  4. mojounwin
    Joined: Dec 2004
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    Location: Queensland, Australia

    mojounwin Junior Member

    Hi, thanks for all the responses. Still weighing up the options.

    Cheers
    Mojo
     
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