ICF靶用酚醛类气凝胶的制备及氢、氘吸附应用研究

【作者】 王朝阳；

【导师】 唐永建；

【作者基本信息】 中国工程物理研究院 ， 凝聚态物理， 2006， 博士

【摘要】 碳气凝胶具有独特的多孔结构，它的高比表面积、纳米级孔隙、纳米级骨架碳微粒以及非晶态的结构形态等特性，有利于增强碳气凝胶的表面吸附能力。碳气凝胶是通过多官能团的酚类化合物和醛在碱性催化剂作用下，经过溶胶-凝胶、酸洗老化、溶剂交换、超临界干燥以及高温碳化过程制备而成。碳气凝胶在力学、声学、电学、热学以及光学等领域都有潜在的应用价值，而在惯性约束聚变(ICF)和民用储氢方面的应用研究备受关注。 本论文在制备酚醛类有机气凝胶和相应的碳气凝胶的过程中，改进了气凝胶的制备工艺，达到了缩短气凝胶制备周期、提高气凝胶质量和降低气凝胶制备成本的目的。 在气凝胶制备的溶胶凝胶阶段，采用超声波恒温加热的方法提高了凝胶化速度，有效地抑制了凝胶过程中酚类物质氧化的影响，经过超声加热所制备的有机气凝胶其透明性较好，气凝胶的品质得到了改善。 在溶剂交换过程中，采取了两种方式来加快溶剂交换的速度。一是采用低强度的超声波作用，使丙酮交换含水凝胶中水的速率提高了上万倍，同时通过控制作用时间，在提高交换速率的同时保持了凝胶结构不被破坏。二是采用由蠕动泵带动的循环流动法进行溶剂交换，对于高密度凝胶可以提高其交换速率，但由于存在一定的压力，低密度样品的形态受到一定的影响。 在改进的工艺条件下制备了多种有机气凝胶及相应碳气凝胶材料。以间苯二酚和甲醛为原料，以水为溶剂制备了间苯二酚-甲醛(RF)气凝胶。制得的有机气凝胶透明性较好，碳化处理后气凝胶的结构均匀，其密度由反应物浓度和催化剂浓度控制；以间苯三酚和甲醛为原料，以乙醇-水混合物为溶剂制备出了透明性比RF气凝胶更好，密度更低(＜20mg／cm~3)的间苯三酚-甲醛(PF)有机气凝胶和相应的碳化气凝胶(CPF)；以对苯二酚和甲醛为原料，在高催化剂浓度(对苯二酚与催化剂的摩尔比H／C＜100)条件下，成功制备出了对苯二酚-甲醛(HF)有机气凝胶和相应的碳气凝胶(CHF)样品，所制备的HF的透明性较RF的差，很难制备成低密度的HF气凝胶。 为改善气凝胶的孔结构，进行了气凝胶的改性研究。以间苯二酚(R)、对苯二酚(H)以及甲醛为原料，合成了不同R：H配比的间苯二酚-对苯二酚-甲醛(RHF)复合有机气凝胶及相应的碳气凝胶(CRHF)。复合气凝胶的制备存在最佳的R：H比例关系，在最佳的R：H配比下，反应最容易进行，制备出的复合有机气凝胶透明性最好，密度可以进一步降低。 开发了一种利用超声波粉碎机进行超声乳化，将RF反应体系均匀分散于不溶性油相中，经过乳液聚合和乙醇超临界干燥制备出了亚微米级有机气凝胶粉末，并建立了经更多还原

【Abstract】 Carbonized aerogels have some excellent properties such as their special porous structure, larger specific surface area, nanoscale pore, nanoscale framework and non-crystalline structure, which are favourable to enhance the surface adsorption potential. The polymerization of resorcinol with formaldehyde catalyzed by alkali catalyst results in the formation of organic aerogel via a sol-gel process, acid aging process, and supercritical fluid drying. Upon pyrolysis of organic aerogel at high temperature, the carbonized aerogel can be obtained. The carbonized aerogel is widely used in the field of mechanics, acoustics, electricity, calorifics and optics, and it is noticeable in the application research of the inertial confinement fusion (ICF) and hydrogen storage used in the civil cases.This dissertation has firstly developed a new technology process to modify carbonized aerogels in the preparation of resorcinol-type organic aerogel and corresponding carbonized aerogel, which attains to the destination of shortening the preparation time of aerogels, increasing the quality of aerogels, and reducing the cost of aerogel’s preparation.In the sol-gel process of preparing the organic aerogel, the gelation speed is increased by means of ultrasonic heating at constant temperature, which is efficient to inhibit the oxidation of resorcinol-type substance in the gel process. The transparency of the prepared organic aerogel is excellent, and the aerogel’s quality is improved.In the course of solvent’s exchange, two kinds of methods have been adopted to expedite the solvent’s exchange speed. Firstly, low-intensity ultrasonic is used to elevate the exchange speed of acetone replacing water from the aerogel containing water up to ten thousand times. Meanwhile, the aerogel structure can be kept through controlling the exchange time. Secondly, the solvent exchange is circularly employed. It is easy to raise the exchange rate for the high-density aerogel, while it has some effect on the low-density aerogel due to the pressure.Several kinds of organic aerogels and corresponding carbonized aerogels are prepared according to the modified technology process. The resorcinol-formaldehyde (RF) aerogel is prepared through the polymerization of resorcinol (R) with formaldehyde (F), and water is used as the solvent. The prepared organic aerogel is transparent, the structure of carbonized aerogel is uniform, and its density is controlled by the reactant concentration and catalyst concentration. When the mixture of alcohol and water is used as the solvent, the transparency of the PF and corresponding CPF aerogels from the polymerization of phloroglucinol and formaldehyde is better than that of RF aerogel, and their densities are lower (< 20 mg/cm~3).更多还原