Research On Hollow Ceramic Heat-insulating Fiber With The Morphology Of Reed Fiber

Ceramic fiber material is widely used in high temperature insulation parts for its great performance on high temperature resistance,chemical stability,thermal conductivity,oxidation resistance and mechanical vibration resistance.Common thermal insulation ceramic fibers include zirconia fiber,aluminum silicate fiber,alumina fiber,mullite fiber,etc.The thermal insulation ability of solid ceramic fiber prepared by traditional method is lower than that of hollow fiber.There are many plants or plant fibers with excellent thermal insulation performance in nature because of their fluffy and slender structure observed,especially for the plants with hollow structure including reed,pampas,kapok,white grass and etc.Their thermal insulation performance is improved by reducing the heat conduction and convection with the hollow structure.According to the genetics,natural hollow reed fibers were took as templates for preparations of the hollow ceramic fibers.The natural fibers were immersed in the mixture solution for a period of time and dried to precursor fibers after taking out.The hollow fibers were prepared by sintered methods on precursor fibers,including zirconia,alumina and aluminum borate based insulation fibers.The obtained fibers have excellent performance on thermal insulation and heat stability.The effects of impregnation solution concentration,yttria doping ratio,aluminum chloride doping ratio and sintering temperature on the composition and thermal insulation properties of zirconia based fibers prepared by reed template were discussed.The structure,morphology,phase,functional groups,constituent elements,pore size distribution and thermal insulation properties of residual zirconia based fibers were characterized.It was found that Zr O₂ based fiber formed double-layer tube and composite tube due to the different absorption degree of reed fiber to metal ions after doping high concentration aluminum chloride.The phase composition and thermal insulation properties of reed genetics Al₂O₃fibers prepared with different sintering temperature and impregnation solution system were researched.It was found that the genetics Al₂O₃ Fiber prepared by sintering temperature of1000℃,impregnation solution concentration of 15 wt%and doping 15 mol%zirconia had the best of reed genetics morphology,low thermal conductivity with 0.05564 W/（m·K）and thermal insulation performance.The thermal insulation properties of aluminum borate fibers prepared with template of hollow reed fiber and solid absorbent cotton were compared through the analysis of micro morphology,phase,pore diameter and thermal conductivity.The prepared ceramic fiber with the morphology of natural reed template fiber had better thermal insulation performance than solid fiber,where the best thermal conductivity at 500℃was 0.1134 W/（m·K）for the genetic2 Al₂O₃·B₂O₃ fiber sintered in 1000℃.