Study On Wire Spinning And Thermal Insulation Properties Of Flexible Mullite Fiber Materials

With the development of science and technology,in some special fields,such as aerospace and other important military fields,the demand for high-temperature insulation materials is getting more and more urgent.Mullite fiber is a kind of special fiber with good oxidation resistance at high temperatures.Centrifugal spinning is a spinning method by which sols are spun from fine pores by centrifugal force.It has the advantages of low cost and high production efficiency.The precursor sol used in centrifugal spinning is usually prepared by the sol-gel method,which is easy to operate and the components in the sol can achieve uniform mixing at molecular scale.The combination of these two processes is one of the most studied preparation methods for mullite fiber.In this study,aluminum nitrate and aluminum isopropyl alcohol were selected as aluminum sources,and ethyl orthosilicate was used as silicon sources to prepare aluminum silicon precursor sol.In this process,the influence of polymer type and polymer concentration on the spinnability of aluminum silica sol was explored.Through a series of characterization techniques,including p H value,viscosity,particle size,and other parameters,the most suitable spinning agent was determined to be polyvinylpyrrolidone(PVP),which has excellent spinnability at 60 ℃.The diameter of the primary fiber is gradually coarser with the increase of the concentration of the polymer.Based on the morphology of the primary fiber and the thermal decomposition of excessive PVP at high temperatures,the structure of the fiber was affected.In the subsequent sintering process,the primary fiber was prepared by adding 15%PVP.Different calcination processes(900,1000,1100,1200,1300 ℃)were used to obtain mullite fibers with different morphologies.The fibers calcined at 1300 ℃ had the smallest diameter,complete Mullite crystal structure,but cracks on the surface.Using mullite fibers to prepare aerogel materials with different volume densities,the lowest thermal conductivity is 0.02836 W/(m·K),and in practical applications,under the conditions of 400 ℃ or butane torch directly burning conditions have significant thermal insulation effect.Considering the above factors,mullite fiber was successfully prepared by the centrifugal spinning method in this paper,and the prepared mullite fiber had good surface morphology,a small diameter,and a high degree of mullite fossilization.Compared with traditional Mullite fiber material,the thermal conductivity of Mullite fiber wiki aerogel material prepared by subsequent application was significantly reduced.In practical application,it shows excellent high-temperature resistance and heat insulation performance,which provides a new research and development idea for the future development of related high-temperature insulation materials.