无机酸铝体系氧化铝连续纤维的制备技术研究

Preparation of Alumina Ceramic Continuous Fibers with Inorganic Acidic Aluminum Sol as Precursor

作为一种性能优异的耐高温结构增强材料,氧化铝连续纤维应用广泛,但其规模化制备流程长,技术难度大。本研究以自制的铝溶胶和市售硅溶胶为前驱体,研究了铝溶胶的微观结构和组成,探讨了溶胶具有优异可纺性的原因。通过溶胶-凝胶结合干法纺丝技术制备了氧化铝基凝胶连续纤维,纤维长度可达1500 m以上,进一步高温陶瓷化后形成了直径约为10μm、主晶相为γ-Al_(2)O_(3)和无定型SiO2的氧化铝陶瓷连续纤维,其中在1100℃下煅烧30 min所制备的纤维单丝平均拉伸强度达到2.0 GPa。微观结构分析表明陶瓷纤维结构致密,其中粒度仅为10~20 nm的γ-Al_(2)O_(3)晶粒均匀分布于无定型SiO_(2)中,使纤维表现出优异的力学性能。该制备过程绿色简单可控,具有产业化应用前景。进一步对氧化铝连续纤维的耐高温性能进行了分析,结果表明氧化铝连续纤维可在1000℃长时间使用,短时使用温度可达1300℃。

As a high-temperature-resistant structural reinforcement material with excellent performance,alumina continuous fiber has been widely used in various fields.However,its large-scale preparation is still a great challenge due to the technical difficulty.Herein,the alumina continuous fibers were prepared using self-made aluminum sol and commercially available silica sol as precursors,in which the microstructure and composition of aluminum sol were studied to reveal their excellent spinnability.Preparation of alumina-based gel continuous fibers with length longer than 1500 m was realized by Sol-Gel combined dry spinning technology.After calcination at 1100℃for 30 min,the continuous ceramic fiber composed ofγ-Al_(2)O_(3)and amorphous SiO_(2)with the diameter and mean tensile strength of 10μm and 2.0 GPa was successfully obtained.Microstructure analyses revealed high relative density of the ceramic fibers,in which theγ-Al_(2)O_(3)nanocrystals with size of 10–20 nm uniformly distributed in amorphous SiO_(2),resulting in excellent mechanical properties.This preparation process is environment-friendly,simple and controllable,showing great potential in practical application.The test for high temperature resistance revealed that the alumina continuous fiber can work for a long time at 1000℃while it can endure as high as 1300℃for a short-time service.