Preparation And Properties Characterization Of Alumina Ceramic Fiber

Alumina fibers have been extensively investigated because of their excellent properties. In this paper, alumina continuous fibers and alumina-zirconium fibers were prepared by sol-gel technology. Alumina continuous fibers were prepared by dry spinning technology. The formation process of spinnable sol, fiber preparation, microstructure of calcined fibers and their mechanical properties were discussed. Meanwhile, alumina fibers containing different amounts of SiO2were fabricated, and the effect of SiO2on the microstructure of alumina fibers has been investigated. Alumina-zirconium fibers were prepared by centrifugal spining technology. The effect of zirconium/aluminum proportion on the fibers thermal properties and the effect of yttrium oxide on the microstructure have been investigated.1. Preparation and characterization of alumina continuous fiberIn this study, alumina continuous fibers were prepared by sol-gel combined dry spinning technology. The progress of fiber formation, characterization and mechanical properties were researched. The sol was prepared after reflux and aging with aluminum salts, aluminum powder and aluminum isopropoxide as the precursors and nitric acid as the catalyst. The gel fibers with diameter15-30μm were obtained by dry spinning under suitable conditions. The xerogel fibers transformed to γ-Al2O3fibers and α-Al2O3fibers though different temperature calcinations. And these were characterized by TG-DSC, IR, XRD and SEM. Meanwhile, alumina fibers containing3wt%SiO2and5wt%SiO2were fabricated, and the changes due to silicon oxide were observed. The strength ofγ-Al2O3fibers was tested, and the fibers strength increased as the diameter decreased. The strength ofa-AlO3fibers were too small to test, so the techniques were needed to improve.2. Fabrication and insulation properties of alumina-zirconium fibers In this study, alumina-zirconium fibers were fabricated by sol-gel combined centrifugal spinning technology. Aluminum isopropxide was dissolved to formic acid aqueous, and then zirconium acetate solution was added with selectively adding yttrium nitrate. The two systems were mixed well by stirring before aging in a water bath. The experiment showed that the zirconium/aluminum ratio and aging temperature had great impacts. When content ZrO2was less than30%or the aging temperature was more than50℃, the solution would appear precipitate. The conditions, such as viscosity of the sol, temperature, humidity and rotating speed, were important for forming gel fibers. The fibers were obtained and characterized by TG-DSC, IR, XRD, SEM and thermal conductivity analysis. It was studied that Y2O3could inhibit the growth of grains and make fibers much denser. The thermal conductivity of fibers with50wt%ZrO2was0.05403W/m·K, which was the lowest.