bend test for thermal-sprayed zinc
bend test for thermal-sprayed zinc
(OP)
Can anyone think of a reason one should be failing bend tests but passing pull-off adhesion tests?
Also, I wonder if we're failing or just doing the test wrong. The obvious fails look just like the failing picture in SSPC CS-23 or AWS C2.18. But the rest look just like the "marginal" picture, except that a sharp knife will pick off the coatings at every crack location. Does "lifting" mean doesn't take much with the knife to knock it loose, or we can pick it off in any way? Does "knife" mean dull putty knife, or sharp utility blade?
Hg
Also, I wonder if we're failing or just doing the test wrong. The obvious fails look just like the failing picture in SSPC CS-23 or AWS C2.18. But the rest look just like the "marginal" picture, except that a sharp knife will pick off the coatings at every crack location. Does "lifting" mean doesn't take much with the knife to knock it loose, or we can pick it off in any way? Does "knife" mean dull putty knife, or sharp utility blade?
Hg
Eng-Tips policies: FAQ731-376: Eng-Tips.com Forum Policies





RE: bend test for thermal-sprayed zinc
Hg
Eng-Tips policies: FAQ731-376: Eng-Tips.com Forum Policies
RE: bend test for thermal-sprayed zinc
A little note as I know your are probably held down by spec's we went to 100% Al flame spray on all components because we were having so much trouble with the Zinc. We tried the 85/15 material
but it was no better in our application.
Is the substrate metal or concrete?
RE: bend test for thermal-sprayed zinc
Here's something to wonder about--coating thickness is measured from the peak of the profile to ensure coverage. But if you take a micrometer to the pieces that flake off, they're considerably thicker because they include profile depth. So, for the purpose of determining mandrel size for bend test, should one be including or excluding the profile depth from consideration?
Hg
Eng-Tips policies: FAQ731-376: Eng-Tips.com Forum Policies