Growth control of whiskers on the surface of alumina fibers
Alumina(Al2O3)fiber-based composite materials are widely utilized as thermal insulation materials in the aerospace industry.However,the weak interface bonding between Al2O3 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 Al2O3 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 Al2O3 fiber/mullite whiskers compo-site on the mechanical properties of the composite material was studied by incorporating SiO2 aerogel.The results indi-cate 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 Al2O3 fibers enhances the SiO2 aerogel,resulting in a compressive strength of 38.3 kPa at a 10％strain loading,representing a 70％improvement in mechanical perfor-mance compared to pre-growth conditions.
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