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在分析和综述大量文献以及多年研究工作的基础上,针对硼化钛和六硼化镧在制备方面存在的问题,提出了自蔓延冶金制备陶瓷粉末的方法。首次系统地研究了自蔓延冶金法制备TiB_2的各个环节(SHS、浸出和表征),获得了优质的TiB_2微粉。TiB_2微粉的平均粒径达0.41μm,比表面积5.685m~2/g,晶格常数a=3.033,c=3.230。在粒径、比表面积和纯度等性能方面均优于文献报导值。粒度分析表明,通过改变初始条件(稀释剂MgO、TiB_2,压坯压力),可以改变TiB_2颗粒分布。考察了燃烧模式和热爆模式两种自蔓延过程;分别研究了预热温度、压坯致密性(或孔隙度)和稀释剂对SHS燃烧波传播速度、燃烧温度的影响,并测量了热爆模式的起爆温度。建立了宏观分层的动态模型。利用SEM和微区分析技术对SHS产物形貌和显微结构进行了分析和研究。提出了TiB_2微粒在氧化镁颗粒间隙和在氧化镁颗粒内部生长的两种机制,该机制能很好地解释粒度分布出现的不连续性。 采用同样的方法成功地合成了LaB_6微粉,为稀土硼化物的制备找到了一个简便易行的新方法。 从热力学和动力学的不同的角度研究了TiO_2+B_2O_3+Mg和La_2O_3+B_2O_3+Mg间的反应过程。并确定了相应反应的劝力学参数。
On the basis of analyzing and reviewing a large number of literatures and years of research work, aiming at the problems in the preparation of titanium boride and lanthanum hexaboride, a method for preparing ceramic powder by self-propagating metallurgy was proposed. For the first time systematically studied the various steps (SHS, leaching and characterization) of TiB_2 prepared by SHS, and obtained the high quality TiB 2 micropowder. The average particle size of TiB 2 powder is 0.41 μm, the specific surface area is 5.685 m 2 / g, the lattice constant is a = 3.033, c = 3.230. In terms of particle size, specific surface area and purity properties are better than the reported value. Particle size analysis shows that the particle size distribution of TiB 2 can be changed by changing the initial conditions (diluent MgO, TiB 2, pressure of green compacts). The effects of preheating temperature, compactness (or porosity) of compacts and diluent on the propagation velocity of SHS combustion wave and combustion temperature were investigated respectively. The effects of heat explosion Mode detonation temperature. Established a macro-layered dynamic model. The morphology and microstructure of SHS were analyzed and studied by SEM and micro-area analysis. Two mechanisms of TiB 2 particles growing in the gaps between MgO particles and inside the MgO particles are proposed. This mechanism can well explain the discontinuity of particle size distribution. The same method was used to synthesize LaB_6 fine powders successfully, and a new and simple method was found for the preparation of rare earth borides. The reaction process between TiO_2 + B_2O_3 + Mg and La_2O_3 + B_2O_3 + Mg was studied from different aspects of thermodynamics and kinetics. And determine the corresponding reaction of the persuasion parameters.