胶体水热法制备纳米二氧化锡粉体的研究

【作者】 刘冬；

【导师】 施哲； 朱云；

【作者基本信息】 昆明理工大学 ， 有色金属冶金， 2003， 硕士

【摘要】 本文通过对国内外大量文献的分析，对制备纳米粉体的十多种方法进行了比较。取溶胶—凝胶法和水热法各自的优点，结合形成新的制备方法——胶体水热法。用胶体水热法制备纳米二氧化锡粉体，避免了纯溶胶—凝胶法后期用高温煅烧得到二氧化锡超细粉体时产生的硬团聚现象。 该法包括两步：第一步，应用溶胶—凝胶法制备纯净的浓缩锡酸凝胶。第二步，利用水热脱水法去除凝胶中的结晶水制得纳米二氧化锡粉体。 第一步的实验，对制备凝胶的影响因素进行了锡盐溶液浓度、反应终点PH值、反应溶剂的研究。得出了最佳实验条件：溶液初始浓度30g／100ml，反应终点PH值2.5，反应溶剂采用去离子水。水解终点的PH值越低，凝胶越稳定。同时对凝胶的洗涤机理进行了探讨，得出胶体老化和离心洗涤对去除Cl~-离子有着显著作用。通过差热—差重检测表明所得凝胶反应温度低，具有良好的表面性能。 第二步对水热法制备粉体的特点和机理进行了探讨，对实验中的压力、时间、反应介质对产品性能的影响进行了研究。通过大量的实验检测，确定工艺参数为压力4～6atm、时间4hour时，能够制备出形成软团聚状态产品。通过实验，认为无机物的低表面张力特性并不是消除粉体团聚的主要原因。实验所得纳米粉体与火法煅烧样品相比，产品具有粒径小、粒度分布窄、团聚程度轻等特点，并且为进一步采取措施进行分散提供了可能。 为改善颗粒的分散性，对液相合成纳米粉体普遍存在的团聚以及相应机理进行了探讨。对解决团聚的分散方法进行了评述。实验考察了三种表面活性剂在水热过程中对颗粒的分散效果。考察了在水热过程中表面活性剂对颗粒的分散效果，确定了最佳表面活性剂为：柠檬酸，加入的剂量为：0.05—0.1g／50ml。并采用真空干燥、球磨后续措施对纳米二氧化锡粉体进行进一步的分散。经真空干燥和球磨粉碎后得到团聚程度低，粒度细小均匀，达到纳米水平并具有较好分散性的球形二氧化锡粉体。实验所得纳米二氧化锡粉体与国外同类产品相比较，具有粒径细小、颗粒外形好、粒度均匀和良好的分散性等特点。 进行了公斤级扩大实验，提出了工业化实验中可能面临的制胶、洗涤、固液分离、防腐，干燥和分散等问题，以及对应的解决措施。更多还原

【Abstract】 The nanometer tin dioxide powder aspects were prepared with the colloid-hydrothermal system which takes the merit of sol - gel law and hydrothermal method, and combine forming new preparing method -colloid-hydrothermal after the analysis of a large number of documents to the home and abroad and comparing to more than ten kinds of methods preparing the nanometer powder aspect, the nanometer stannic dioxide powder is prepared with the colloid hydrothermal system, and has avoided the pure sol - gel law to calcine with high temperature later period which causes the hard agglomeration.This law includes two steps: First step apply the sol - glue system to prepare pure concentrated stannic acid gel. Second step, the nanometer tin dioxide powder aspects are gone except the water of crystallization system by the way of hydrothermal. First step of the experiment, the research of terminal point PR’s value, stannic salt solution consistency and reacts solvent that the influence factor of gel to prepare has been carried on. The optimum experiment condition has been reached: Solution initial consistency reaction on 30g/100ml,’s terminal point value reaction on 2.5,’s PH’s solvent use purified water. The gel is more stable to less PH’s value of hydrolysis terminal point Proceed with research to centrifugal washing mechanism at the same time, and the conclusion is that centrifugal wash possess the notable effect in eliminating Cl" ion. TG-DTA detection indicates the gel possesses the good superficiality ability. The research has been in progress to second step of characteristic and mechanism to hydrothermal preparing the powder aspect, and research has been in progress by pressure to in the experiment, time and the influence to the product capability of reaction medium. By way of a large number of experiment detection, the technology parameter for when pressure 4~6atm and time 4hour can be prepared out to form the soft agglomerative state product. By way of the experiment, think thatthe low surface tension property of inorganic material is not the major cause to eliminate the powder aspect to reunite . The new method is compared with the ordinary fire law, the characteristic of product such as to possess that the diametre is small and the size distributes narrow and the agglomeration level is light etc, and for further adopting the measure scatters providing the possibility.To improve the dispersivity of particles, research the agglomerative mechanism that the nanometer powder aspect universally exists to the liquid phase. Scattered effect having inspected the active agent of first cousin’s face at hydrothermal course to the anything small and roundish has been defined that the active agent of optimum surface is : Dosage joined is the citric acid : 0.05-0.1g/50ml . And use that the vacuum is dry and the follow-up measure of sphere mill to the nanometer two tin oxide powder aspects to be in progress further to scatter. After the vacuum dry and the sphere mill, the level of agglomeration is low, the particle size is very small, spherical and the nanometer stannic dioxide powder with the aspects of good scattered nature is achieved. With the contrast of same product of abroad, it is very small to possess the particle diametre, the good characteristic of scattered nature.Having carried on level of kilogram experiment, has put forward the industrialize experiment what probably is faced with synthesis, wash, solid liquid separation, antisepsis, dry and dispersity etc, and the improvement measure of such problem.更多还原