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I am interested in putting a small (3"x3"x2") assembly under X-ray, following a shock test, in order to evaluate failures of an internal ceramic piece. Unfortunately, this assembly utilizes quite a bit of potting material (epoxy) and as such, cannot easily be disassembled.

I'm considering reaching out to some local dentist practices to see if I can purchase X-ray time from them, however, I'm concerned that the material makeup of my assembly will not allow adequate penetration and will result in a poor image.

The general makeup of the assembly from the outside and moving inwards is...

  • 0.125" thick aluminum outer casing
  • 0.25" to 0.5" foam-like epoxy
  • some small (but strong) magnets
  • a ceramic "skeleton" structure (this is what I'm most interested in evaluating for failures)

Should note that the magnets are not necessarily in the line-of-sight of the ceramic, so 'penetration-ability' of those is a non-issue.

However, regarding the aluminum, with a HVL of 0.06" at 120 keV (source), I'm worried that I may not be able to sufficiently penetrate the outer shell and produce a good image.

MY QUESTIONS ARE:

  • Penetration aside: Is it reasonable to suspect that I will be able to gather useful information and identify fractures in the ceramic?
  • Google tells me that the typical energy capability of a dentistry x-ray is <200 keV. For someone with experience in the radiation field, do you expect this would be sufficient to penetrate my test article and produce a good image?
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    $\begingroup$ A side comment since the answer explains why this won't work for you, but if you want more substantial X-ray testing, try a vet who specializes in large animals. An X-ray machine designed to deal with a horse is likely to be more powerful than your dentist's. I know someone who restores old musical instruments who has X-rayed things the size of an 150-year-old piano that way. $\endgroup$
    – alephzero
    Apr 4 '20 at 13:39
  • $\begingroup$ Excellent idea. Thanks! $\endgroup$ Apr 6 '20 at 16:29
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X-rays are a poor way to test for cracking in a ceramic. A crack in a ceramic part which has not shattered to pieces is a very small feature, of order ~0.001" wide or less, which commonly-used x-ray equipment cannot resolve. Second, a tiny crack in a ceramic part does not present a significant difference in x-ray absorptivity, inelastic scattering, or diffraction between the cracked and uncracked regions to the incoming x-rays which means that a tiny crack will not produce x-ray contrast in the imaging apparatus.

In addition, the materials which enclose your ceramic part will have the effect of attenuating and scattering the incoming x-rays which degrade their ability to resolve useful contrast in that portion of the "sandwich" you need to find cracks in.

In light of this, you would be better off trying another sort of nondestructive testing technique than x-radiography.

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  • $\begingroup$ Hey @niels nielsen, I appreciate the input. I'll go back to the drawing board. Thanks for saving me time and money! $\endgroup$ Jan 6 '20 at 19:36

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