How to increase alumina washcoat on ceramic substrate

Hi,
I'm trying to increase alumina washcoat amount on ceramic substrate, but everytime I failed because of low adhesion ability.
Can you tell me the best procedure for alumina washcoating. It's similar 3 way catalyst system.
Thanks in advance.
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Could we get more info, Please?
What is the substrate? How are you preparing it? Why not solid alumina?
tom
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snipped-for-privacy@email.msn.com (Tom Walz) wrote in message

Hi, Tom. Thanks for response.
Substrate is commercial cordierite honeycomb with 400 cpsi. I tried with 50% solid percent gamma alumina slurry(pH=3.5), after dipping substrate on slurry for 1 minute, finally air blowing.. Actually am thinking this solid % of 50% is too high.. I don't understanding last question of solid alumina, I'm using gamma alumina as solid powder and ball milling was applied to adjust to particle size of 2~10 nm size.
Do-Woan Kim
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Do-Woan Kim wrote:

2-10 nm? Did you mean 2-10 microns? Getting 2-10nm from ball milling is quite a trick. There are a variety of green binders you can use if your doing some post firing. There are also a variety of aluminas in the nm size you can use in a small percentage as a binder. If your getting 50% solids and low viscosity from 2-10 nm particle size - that's unusual. What's the surface area of the alumina?
Gregg
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