I tried to make a cup-shaped sample with ceramic materials. To do that, I intruded a spacer into the center of the materials powder compact before the sintering process. After sintering, I found that the spacer had been adhered to the sintered body. To avoid this, I think I need to coat my spacer with a release agent, before intruding it to the materials powder compact. Can anyone suggest me a good release agent in this case? Could you tell me your idea to avoid this adhesion?
Dear Son,
As Eric said, we use BN too, by solving it in alcohol and pianting onto the contact surfaces. the coating process needs a very short time, for example less than 10 minutes, while the slurry is dried. sometime we prepared the BN coat one day before sintering and sometimes we do densify immediately.
Dear Eric Neuman,
Thank you for your information! Could you please explain more about the using of Boron nitride as a release agent? (For example, how to coat it on the spacer/mold, how long the coating process, how long it should be prepare before the sintering…)
Best regards
We apply it as an aerosol spray. It can also be dispersed in a solvent and painted onto the spacer with a brush. The only problem you will need to look out for is a CTE mismatch between your sintered part and the spacer. If the CTE of the sintered part is larger than the spacer, no release aid will help. This is because the spacer will end up being compressed into place by the sintered part (assuming the part doesn't break from the stress).
We purchase our high purity BN spray from Materion in the US. It is also sold in lower purities through commercial and industrial supply catalogs. You can also try making a slurry out of h-BN powder, with a solvent and a binder. Wait till it dries before using with your powders.
Dear Son,
As Eric said, we use BN too, by solving it in alcohol and pianting onto the contact surfaces. the coating process needs a very short time, for example less than 10 minutes, while the slurry is dried. sometime we prepared the BN coat one day before sintering and sometimes we do densify immediately.
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