氧化铝纤维表面晶须的生长控制

Growth control of whiskers on the surface of alumina fibers

氧化铝(Al_(2)O_(3))纤维基复合材料是广泛应用于航天航空领域的隔热材料,但Al_(2)O_(3)纤维与复合基体间的弱界面结合导致的界面失效会极大地影响纤维增强效果,通过真空浸渍和冷冻干燥技术在Al_(2)O_(3)纤维表面生长莫来石晶须可以有效解决此问题。文章采用扫描电镜(SEM)、透射电镜(TEM)和X射线衍射分析(XRD)对莫来石晶须的表观形貌、晶型结构进行分析,探讨了碱硅胶用量对晶须生长形貌的影响,最后将其与SiO_(2)气凝胶复合研究Al_(2)O_(3)纤维/莫来石晶须的界面增强对复合材料力学性能的影响。结果表明:碱硅胶用量为2.8 mL的莫来石晶须形貌最佳,直径约为60 nm,与标准卡片对比证明所长晶须确为莫来石晶须。生长莫来石晶须的Al_(2)O_(3)纤维/莫来石晶须增强SiO_(2)气凝胶在10%应变的加载下压缩强力为38.3 kPa,较生长前提高了70%。

Alumina(Al_(2)O_(3))fiber-based composite materials are widely utilized as thermal insulation materials in the aerospace industry.However,the weak interface bonding between Al_(2)O_(3)fibers and the composite matrix significantly affects the fiber reinforcement effectiveness.To address this issue,vacuum impregnation and freeze-drying techniques were employed to grow mullite whiskers on the surface of Al_(2)O_(3)fibers.The apparent morphology and crystal structure of the mullite whiskers were analyzed using scanning electron microscopy(SEM),transmission electron microscopy(TEM),and X-ray diffraction(XRD).The influence of the amount of alkali silica sol on the morphology of whisker growth was investigated.Additionally,the effect of interface enhancement of the Al_(2)O_(3)fiber/mullite whiskers compo-site on the mechanical properties of the composite material was studied by incorporating SiO_(2)aerogel.The results indicate that the optimal morphology of mullite whiskers is achieved with an alkali silica sol dosage of 2.8 mL,resulting in whiskers with a diameter of approximately 60 nm.Comparison with standard reference samples confirms that the grown whiskers are indeed mullite.The growth of mullite whiskers on Al_(2)O_(3)fibers enhances the SiO_(2)aerogel,resulting in a compressive strength of 38.3 kPa at a 10%strain loading,representing a 70%improvement in mechanical performance compared to pre-growth conditions.