alumina membranes by slip casting 1

[inont]

Does anyone knows what is the right dispersant for alumina?
I'm having difficulties while casting my slip (my slip is not dispersed). I'm using composition of alumina, kaolin, and quartz.
My aim is to obtain a thin cylindrical membrane, so I also have a problem with the heating rate because my membranes always cracks.
I choose slip casting because my lab doesn't have modern equipment for techniques such as CVD or solgel.

 

[potter]

Ammonium polyacrylate at a pH of 9 should be sufficient,also if the purpose is to produce a thin
membrane,perhaps anodising an aluminium tube
heavily,then dissolving the xs aluminium away might be
an approach for low-temperature applications (the
anodising produces a layer of Boehmite Al(OH)O ,
which is not high temperature stable).

 

We are fabricating alumina ( 99.8 % ) tray of dimension 200*200*100 mm by slip casting. The thickness is 8 mm . The casting is OK and the surface afterr casting is OK. we are using a polyacrylate based dispersant for the slip. We keep the article at room temperaturew after releasing from the mould for three days prior to putting in an electrical oven. We keep articles at 50 deg. C for 24h prior to increase the temperature.

Problem: We are observing cracks at drying stage. We have tried at least 50 such pieces with minor modifications in slip, in oven, in compositions etc, but not successful. Can somebody suggests some solution in this regard.



L. N. Satapathy
lnsatapathy@vsnl.com