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We have porous ceramic platelets of ~50x5x1 mm³ thickness infiltrated with ammonium nitrate solution (NH4NO3). We want to decompose and evaporate it w/o damaging the fragile substrate (decomposition should take place at ~210 °C)

Since this is part of a repeated experimental procedure, it shouldn't take longer than ~15 minutes for heating, decomposition and cooling back to max ~50 °C for a batch of 10 to 20 samples at once.

I was thinking about a microwave furnace since it would heat only the samples, or maybe even only the ammonium nitrate within the samples (not sure how well ceramics (ZrO2) couples in the µwave), but since it will heat the material uniformly, I'm concerned about explosive evaporation and damage of the fragile samples. Might still be suitable if the power is tuned well.

What also came to my mind was inductive heating of a small metal sample carrier or sample holding capsule. Could also be quick. However I have no idea if lab devices like this are available, at least I've found nothing.

Any other ideas?

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  • $\begingroup$ If the ceramics are water stable and porous, why not wash the ammonium nitrate out? $\endgroup$ – Beerhunter May 8 '18 at 21:56
  • $\begingroup$ Haven't thought about it yet. Drying the water afterwards will at least impact less stress on the substrate (we need dry samples in the end). That makes an additional process (=time). Also it might be tedious to really wash out most of the ammonium nitrate due to the narrow pore structure (judgement of a chemical engineering colleague). So it wouldn't be my preferred solution. $\endgroup$ – ascripter May 9 '18 at 9:23
  • $\begingroup$ Are you not concerned about heating an explosive to decomposition then? Continuous (as opposed to batch) washing would be quicker using ambient temp water and then a more volatile solvent to chase water out e.g. acetone or ethanol. Quicker than heating. You can then blow out with nitrogen or air if there isn't deemed to be many volatiles left. $\endgroup$ – Beerhunter May 9 '18 at 11:40
  • $\begingroup$ Yes, I am concerned about it. That's why I want to have good control over the temperature. We are currently doing it with a tube furnace which is very uncontrolled. Parts may get damaged - we have another stress test in the cycle which is supposed to damage the parts, so if the parts are damaged we cannot definitely determine if the stress test or the electrolyte test was the culprit. We want to make the electrolyte removal as improbable a source for damage as possible (but not at the cost of process time). $\endgroup$ – ascripter May 9 '18 at 14:49

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