Preparation of Alumina Fibers by Needle-Less Electrospinning

In this study the needle-less electrospinning by means of “NanospiderTM“ (ELMARCO) as technology for the preparation of fine α-Al2O3 fibers with diameters of 0.5 - 1.5 µm is presented. The fabrication consists of three steps: i) preparation of spinning solution, ii) electrospinning of the prepared solution and collection of the composite fibers, iii) calcination of the composite precursor fibers. The electrospun fibers were prepared from polyacrylonitrile/N,N-dimethylformamide (PAN/DMF) polymer solution and Al(NO3)3.9H2O in ratio 1/10/1. Thereafter, the precursor fibers were calcined in the furnace at 900, 1100 and 1200 °C with a rate of 5 °C/min in air. The formation of crystalline phases, surface morphology and diameters of metastable and final alumina fibers were characterized using thermogravimetric analysis, X-ray diffraction analysis, the scanning electron microscopy and transmission electron microscopy. The precursor PAN/Al(NO3)3 fibers were amorphous. The thermal treatment leads to the phase transition from γ-Al2O3 to α-Al2O3 accompanied by removing of polyacrylonitrile (PAN). The fine porous microfibers composed of pure α-Al2O3 phase were prepared after calcinations at 1200 °C.