I am working on mesoporous alumina systems in the form of thin films, now I wish to explore into its different morphology such as fiber. However, I am stuck in the very first step of its synthesis. Can anyone suggest a proper guidance to the basics of the synthetic route?
In order to receive a correct answer at your question, it is necessary to mention the dimension of alumina fiber what do you want to obtain
Did you try filtering the slurry of alumina precursors through a 200 mesh stainless steel screen?
Since you are working with mesoporous alumina, you might know the paper of the link, anyway...
http://iopscience.iop.org/0957-4484/17/2/002
What about to try approach used for mass production of fiber insulation: They pour melted rock (basalt) on wheels with high speed of rotation. The material is radially dispersed and cools down, producing fibres with diameter about 20 microns. It will of cours depends on the viscosity.
According to the size you want, several methods can be used always now. For size over about mm, mechanical extrusion could be used, it is a convential method in practice. there are main three kinds of techeniques for obtaining fibers size in the range of um-mm, the melt extraction method, the glass cover method and water spinning method, you can find their detail information from the internet. Good Luck!
Look at http://www.sciencedirect.com/science/article/pii/S0022024899002134
Indeed the preparation of Alumina fibre is very important for their application:
Aluminium-tri-isopropoxide dissolved in distilled water to 1 M concentration, refluxed at 80 °C for 3 h in the presence of acid catalyst (0.07 mol nitric acid) and then cooled. Take 100 ml of the prepared sol and add 10, 15 or 20 wt.% of hydroxy ethyl cellulose (HEC) to the sol to obtain spinnability. The sol was then concentrated by the removal of water to achieve required solid loading. When the sol was appropriate for forming fibres, it was taken in a 10-ml syringe and then fibres were drawn in a rectangular glass tray containing ammonia solution. The gelled fibres were taken out from the ammonia solution and dried at room temperature. The dried fibres were then can be sintered .
For detail information you can see the following papers
J. Chandradass, M. Balasubramanian, Sol–gel processing of alumina fibres, Journal of Materials Processing Technology, 173 (2006) 275–280.
B.E. Yoldas, Alumina sol preparation from alkoxides, Am. Ceram. Soc. Bull., 54 (1987), pp. 289–290.
Toshio Maki, Sumio Sakka, Preparation of alumina fibers by sol-gel method, Journal of Non-Crystalline Solids, 100 (1988) 303–308
you can prepare alumina fibers by reaction of water on aluminium metal pieces. dip aluminium pieces in 0,1N HgCl2 solution for few mins. Aluminium surface will get amalgumated which will act as a catalyst. Remove HgCl2 solution by decantation and then keep the aluminium pieces in deionized water. Reaction will start and fibers of AlOOH will form. Separate these particles, dry and then heat at 450 to 500 C for converting AlOOH to Al2O3 fibers.
Hi,
one way of Preparation of alumina fiber is creating a slurry of alumina and additives which are capable becoming stranded .
Czochoralski process
1.Method of melt traction.
2.Single-crystal fibers with special properties are obtained.
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