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溶胶法连续氧化锆纤维制备工艺研究
孙亚娟
Subtype硕士
Thesis Advisor齐涛
2018-07
Degree Grantor中国科学院研究生院
Degree Name硕士
Degree Discipline化学工艺
Keyword氧化锆纤维,溶胶凝胶法,静电纺丝,硅掺杂,计算模拟
Abstract

氧化锆纤维以其质轻,高强度,高韧性,尤其是耐高温(高达2200 ℃)等突出优势,在航天、民用等方面都有广泛而不可替代的应用。然而传统的熔融成纤法难以用于氧化锆纤维的生产,以溶胶凝胶技术为基础的制备工艺逐渐发展起来。国外已经有可用于航天等尖端领域的连续氧化锆纤维产品,但由于技术垄断,国内的氧化锆纤维制备技术发展缓慢,仅有的几家短纤维生产企业也存在过程污染,产品力学性能差等问题。基于此,本文针对氧化锆纤维产品,采用溶胶凝胶法结合静电纺丝工艺进行硅掺杂氧化锆纤维的绿色化、无害化的清洁制备工艺研究。论文的主要研究内容及成果如下:(1)以醋酸锆为锆源,硝酸钇为相稳定剂,以二氧化硅为添加剂制备聚醋酸锆溶胶。该体系制备工艺简单,所得溶胶可纺性好。以聚乙烯吡咯烷酮(PVP)为纺丝助剂,辅助静电纺丝过程凝胶纤维的制备。经合理的热处理工艺处理即可得到颗粒致密(30-60 nm),直径分布均匀(400-700 nm)的四方相氧化锆纤维。(2)以碱式碳酸锆为锆源,醋酸为络合催化剂,醋酸钇为相稳定剂,二氧化硅为功能性添加剂在水溶液中制备前驱体。当纺丝液粘度范围为60-80 mPa·s,n(CH3COOH):n(ZrO2)至少为3时,溶胶可纺性能优良,经静电纺丝可得到长达几十厘米的凝胶纤维。同时对不同醋酸含量下前驱体聚合结构及形成机理进行了探索。(3)考察硅添加对于纤维性能的影响,发现SiO2的添加可有效抑制溶胶过程颗粒长大,获得结构致密表面光滑的氧化锆纤维。相较于未添加组,少量添加SiO2(5 mol%)即可使颗粒直径减小一半,但当添加量超过一定阀值(10 mol%),纤维则变得易脆短促。(4)通过综合热分析,X射线粉末衍射分析等制定了先慢后快的热处理制度。通过对纤维产品晶型及颗粒大小考察,发现Y2O3添加量对氧化锆纤维的晶型影响较大,当添加量达到3%后,即可使氧化锆纤维在室温下保持四方相。(5) 通过分析溶胶和纤维特征,最终确定醋酸锆体系静电纺丝过程参数为:纺丝电压18-20 kV,进料速率0.01-0.02 mL/min,固化距离10-15 cm;碳酸锆体系静电纺丝过程适宜的参数为:纺丝电压20-25 kV,进料速率0.015-0.02 mL/min,固化距离12-18 cm。(6)采用Comsol Multiphysics有限元分析软件对静电纺丝过程进行初步模拟探索。建立简化数学模型,以稳态静电场模块对电场特性进行分析计算,模拟得到纺丝电场电势及场强分布,并模拟加载电压及固化距离对电场的影响。;Zirconia fiber with its prominent advantages, such as light weight, high strength and toughness, especially high temperature (up to 2200 ℃) , plays an irreplaceable role in military and civil. However, the traditional melt-spinning method is difficult to use for the preparation of zirconia fibers. The preparation process based on sol-gel technique has been gradually developed. However, due to the monopoly of technology, the technology for preparing zirconia fiber in China is developing slowly. Existing production processes for staple fibers have various problems, like pollution and poor mechanical performance. Therefore, this paper has carried out a green and harmless cleaning preparation process for zirconia fiber products. The computer simulation-assisted preparation of silica-doped zirconia fibers by sol-gel method combined with electrospinning process was mainly studied. The main research contents are as follows:(1) Using the Comsol Multiphysics finite element analysis software, a simplified mathematical model was established for the electrospinning process. The steady-state electrostatic field module was used to analyze and calculate the electric field characteristics. The electric potential and field intensity distribution of the spinning field were simulated, and . The effect of the loading voltage and curing distance was calculated.(2) Zirconium acetate as zirconium source, yttrium nitrate as phase stabilizer, and silica as additive were used to prepare precursor sol. The sol obtained by this simple preparation process has the advantage of good spinnability. Polyvinylpyrrolidone (PVP) was used as a spinning aid for electrospinning of the sol. A reasonable heat treatment process was explored. The tetragonal zirconia fiber with dense particles (30-60 nm) and uniform diameter (400-700 nm) was successful obtained.(3) In order to prepare spinnable sol, zirconium carbonate was used as zirconium source, acetic acid was complexation catalyst, and silica was used as functional additive. When the viscosity of spinning solution is 60-80 mPa. s and n (CH3COOH): n (ZrO2) is at least 3, the spinnability of sol is excellent and tens of centimeters of gel fibers can be obtained by electrospinning. At the same time, the polymerization structure and formation mechanism of precursors in different systems and different acetic acid contents were explored.(4) The effect of silicon addition on the properties of the fibers was investigated. It was indicated that the addition of SiO2 can effectively inhibit the growth of particles in the sol process and is good for obtaining compact structure and smooth surface. Compared with the blank group, a small amount of SiO2 (5 mol%) can make the particle diameter reduced by half, but when the amount exceeds a certain threshold (10 mol%), the fiber becomes brittle and short.(5) Through comprehensive thermal analysis (TGA/DSC), X-ray powder diffraction analysis (XRD), a combination of slow and fast heat treatment system was developed. Through the investigation of crystalline phase and particle size, it was found that the Y2O3 content has a great influence on the crystalline phase of the zirconia fiber. When the added amount reaches 3%, the zirconia fiber can keep the tetragonal phase at room temperature.(6) By analyzing the simulated electric field and charactering the sols and fibers, the electrospinning parameters of zirconium acetate system were determined as spinning voltage 18-20 kV, feed rate 0.01-0.02 mL / min, and curing distance 10-15 cm. In the zirconium carbonate system suitable electrospinning parameters were spinning voltage 20-25 kV, feed rate 0.015-0.02 mL / min, and curing distance 12-18 cm. 

Language中文
Document Type学位论文
Identifierhttp://ir.ipe.ac.cn/handle/122111/26857
Collection中国科学院过程工程研究所
研究所(批量导入)
Recommended Citation
GB/T 7714
孙亚娟. 溶胶法连续氧化锆纤维制备工艺研究[D]. 中国科学院研究生院,2018.
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