Methods For Preparing Alumina Fibers

There are various methods for preparing alumina fibers, primarily including the sol-gel method, electrostatic-solution jet spinning, centrifugal spinning, impregnation, the slurry method, the melt method, and the prepolymerization method.
The sol-gel method is a preparation process in which soluble aluminum and silicon salts are formulated into a colloidal solution of specific viscosity; this solution is spun into fiber precursors via high-speed centrifugal spinning, followed by dehydration, drying, and heat treatment (crystallization) at medium-to-high temperatures. This method can be used to produce continuous alumina fibers.
Electrostatic-solution jet spinning is suitable for producing ultrafine alumina fibers with diameters of less than 5 μm. Combining the characteristics of both electrospinning and solution jet spinning, this method is well-suited for continuous production.
The aluminum polycarboxylate precursor method is a relatively new technique offering advantages such as good sol stability, excellent spinnability, low cost, and an environmentally friendly heat-treatment process. This method can be combined with electrospinning or centrifugal spinning technologies to produce precursor fibers.
Other preparation methods include the impregnation method, which typically utilizes hydrophilic viscose fibers as the substrate; while this process yields fibers with high strength and diverse morphologies, production costs are relatively high. The slurry method is also known as the DuPont process. The melt method is characterized by a simple process, low costs, and ease of operation, though the resulting alumina fibers have a relatively low alumina content. The colloidal method represents an earlier approach.