Air in Ceramic Slurry

celticmad · Apr 10, 2003

Can anyone tell me if there is a method for removing air from ceramic slurries ?.
We are dipping plastic patterns in the slurry but bubbles are causing scrap on the finished castings.
Anti - Foams are not very effective.Dipping at an angle is better but again not totally effective.
Speed is an important factor.

Ceramicguy · Apr 22, 2003

Put the slurry in a chamber and draw a vacuum ~29". When it stops bubbling it should be deaired. As long as the surface isn't radically disturbed (reentrained air) it should stay reasonably bubble free.

celticmad · Jul 17, 2003

Thanks
Ceramicguy but unfortunately not an option....a full scale production process whereby a board containing the moulds is dipped into the pot and rotated every two minutes.Vacuuming would be too expensive and take too long.
Thanks anyway mate

Henshall · Aug 4, 2003

The reply from ceramicguy was correct. I suspect you are producing your slurry with a relatively high speed impellar and you are introducing air in the batch that way. It is relatively easy to de-air tha slurry in a vacuum vessel prior to pumping to your dipping tank. Ensure you are not introdcing air into the slurry during the pumping operation by always having a slight rise on all the delivery pipes.
Frank Henshall

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Air in Ceramic Slurry

celticmad

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Materials

celticmad

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Henshall

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