I want to make slurry for aqueous tape casting of alumina (500 nm avg. particle size) using PVA binder and PEG plasticizer, but I am not being able to optimize the contents.
1. In what quantity range (wt% or vol%) should I use alumina to get high relative density?
2. In what range (wt% or vol% w.r.t total composition or w.r.t alumina) should I use PVA binder? Should the PVA added be in solid granules form or aqueous solution, and hence will that quantity represent binder active matter or binder solution?
3. Should PEG added be in aqueous solution form?
4. Is optically high grade PET film ok as substrate for tape casting? Can the tape be detached from this substrate easily? (I could not be able to detach yet).
Thank you so much~
Hi Khalid, the weight ratio of the binder additive is relative. It is always better to add PVA in solution format (5% or 10%) so that the slurry mixing time may be reduced and will help in uniform slurry rather than a granule addition.
The substrate seems to be ok, but the tape release problem may be fixed with the addition of some plasticizers or plasticizer combinations for with you may refer to existing literature.
Hello Khalid,
I have some experience working with aqueous alumina tapes, but instead of PVA and PEG, I used an acrylic emulsion that performs both functions (binder and plasticizer).
For this particle size, I sintered tapes with 25 vol% (~52 wt%) at 1550 ºC for 2 h and obtained a relative density higher than 98%.
The solid content will depend on how you performed your slurry optimization (dispersant, binders, etc.). By the correct optimization, you will find the higher solid content and formulation suitable to produce defect-free tapes.
PET film works good as carrier film and should be OK for you to detach the tape. You can use also a silicon-coated PET film that would help you to easily detach the tape. However, in this case, you may need to play with some tricks of the surface stresses between silicon and the ceramic slurry.
Thank you so much Mr. @Mewin Vincent for taking out time for your kind reply. If PVA is added in solution form, then, let's say i want to add 5 wt% binder in slurry, it's active matter (binder solid content) will count as that 5 wt%. But this will also introduce a lot of extra water from the binder solution. Should I remove equivalent water content from initial water I used as slurry solvent?
Thank you so much Mr. @Marcelo Daniel Barros for taking time out for such extensive reply
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