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I Think I came close to a Type III Hardcoat

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  • I Think I came close to a Type III Hardcoat

    I just got a new 30V, 5A max PS, CC/CV and was trying it out. My test piece was about 4 in^2, and I was trying for between 6-8 A/ft^2, so I was only using 0.2 A.

    I watched my voltage rise steadily from about 13V to 30V in the course of an hour, so I knew something was off. I suspected a poor electrical connection, but I let it go...

    Attached are a couple of pictures. The first is the piece directly after I removed it from the anodizing tank. Notice the dark gray color of the wire. I believe this is the beginning of a hardcoat. I think that after a couple of minutes, the electrical connection between the wire and the workpiece was almost completely lost, and the wire was seeing the full current, hence a MUCH higher current density than calculated.

    I dipped it in the dye tank, and confirmed my suspicions that the part was poorly anodized, likely due to a faulty connection. However, it appears that the wire did absorb some dye. I thought that a true Type III hardcoat would not absorb dye. Is this correct?

    Just thought I'd share my experience with you guys. Enjoy!

    Edit: My FTPs not working ATM. I'll get the pics up when I get a chance.

  • #2
    I agree with your assessment that the electrical connection failed. Looking at your pictures, the attachment method is inadequate; you need a method that will tightly bite into the work and the wire, so that electrolyte can not penetrate the connection, anodize the connection, and ruin your electrical continuity.

    I don't know if the anodization on the wire is Type III or not, I'd be inclined to doubt it. Maybe its the remnant of Type III after the high dissolution rate ate most of it away. Type III can be dyed; with considerable difficulty, in dark colors only.