I work with ceramic aqueous suspensions which I pour into a 3D-printed mold. My current problem is the fact that water evaporates too quickly from my samples, causing bubbles and other dislocations that affect structural integrity. I am currently trying to iron out a process which utilizes an H2SO4/H2O mixture that can create a constant humidity environment inside of an empty desiccator, but many times it has been unsuccessful. Any other ideas or reccomendations would be appreciated as to how I can mitigate this issue.
Hi Alex,
your bubbles are probably not caused by evporation of water but by entrapped air from the previous mixing procedures. De-air your suspensions before casting (200 mbar vacuum while stirring, if necessary add a de-foaming agent).
We often do slip casting of square sample plates in silicon frames placed on plaster plates. In order prevent evaporation and drying out of the samples on the top we cover the molds with thick and stiff plastic foil with some weight on top.
Frank
You can try to use humectant in your mixture which are known to prevent water loss
Try to put your samples in an environment with relatively higher humidity and this will decrease the evaporation driving force, hence, decreasing the rate of water loss or evaporation. One way to do this is to supply the storage vessel with humid air (air flow with high humidity) in the first stages of drying process to keep a small difference between moisture contents in different phases which will consequently lower the evaporation rate. Then you can adjust air humidity to achieve reasonable drying and the desired water content.
Eslam Gomaa ِAl-Sakkari Helpful advice. Could you potentially recommend the correct equipment that would be used to supply the humidity-controlled air to the vessel?
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