what are the causes of cracks that appeared on the surface of ceramic foam after drying and how can we avoid them
Possibly shrinkage during the drying - have you considered increasing the drying time?
yes i consider increasing the drying time for 24h at 60 C but i still have that probleme the material is based on calcium phosphate
You may limit the phenomenon by adding surfactant in the formulation, thus decreasing significantly the surface tension of the liquid during drying. Cracks are indeed not only due to shrinkage but to drying stresses caused by capillary forces. Low surface tension combined with low temperature of drying and long time should limit the problem. You might be inspired by published paper about convective drying used to prepare non-cracked xerogels, having properties similar to those of aerogels. The involved phenomena are the same.
Alain
Dear Khallok Hamza
You can:
1. Reduce the water content of primary slurry with addition of defloculant agents so the risk of water vapor decreases
2. Add the grog (sintered material from the batch formulation) to the batch as a anti-propagation of microcracks.
Though I have not worked with foams I can tell my experience with deposition of hydroxyapatite on 316L stainless steel. Thick layers (6 to 10 micrometers) generate cracks. I used three approaches: Absolute ethanol, it dries very fast with cracks.
Used multilayer deposition (electrophoretic) and it works much better. Third, to avoid the rapid ethanol evaporation i used a zeotropic mixture of absolute ethanol and acetylacetone that worked just perfect. As Alberto Ortona says a plasticizer would improve your foam because it lubricates particles past each other while dryng.
If it works for you let me know it and good luck with your foam
- Badges
- Science topic
- Similar topics
- Physical Sciences
- Materials Science
- Materials
- Inorganic Materials
- Ceramics