柔性氧化铝基纳米纤维膜的制备及结构调控研究OA

Alumina(Al2O3)nanofiber membranes are promising high-temperature thermal insulation materials with broad applications in aerospace,firefighting,and rescue operations.However,rapid grain growth during phase transfor-mation tends to cause brittle cracking,limiting their practical use.Element doping is an effective strategy to suppress excessive grain growth and improve the high-temperature flexibility of Al2O3-based fiber membranes.In this study,two-dimensional Al2O3-based nanofiber membranes with good flexibility were fabricated by combining sol-gel and electrospinning techniques with the incorporation of Zr and Si as dopants.Scanning electron microscopy(SEM),trans-mission electron microscopy(TEM),and X-ray diffraction(XRD)were employed to investigate the effects of dopant type,doping ratio,and calcination temperature on fiber morphology and crystal structure.Tensile strength and flexural performance were also systematically characterized.The results show that Zr doping significantly reduces grain size and improves flexibility.However,calcination at 1 400 ℃ leads to noticeable grain coarsening and a marked decline in flexibility.In contrast,when Si is used as the dopant at an Al∶Si molar ratio of 6∶1,the resulting Al2O3-SiO2 nanofiber membrane exhibits uniform morphology and a stable mullite phase.This membrane retains good flexibility after calcination at 1 400 ℃.After calcination at 1 000 ℃,it achieves a tensile strength of 1.03 MPa,maintains a flexural stiffness of 70 mN after 500 bending cycles,and shows a low room-temperature thermal conductivity of 0.029 9 W/(m·K),demonstrating excellent overall performance.