等离子体辅助机械力活化低温合成AlN的研究

发布时间：2018-03-02 04:08

本文关键词： Al N DBDP辅助球磨固态氮源低温合成　出处：《集美大学》2015年硕士论文　论文类型：学位论文

【摘要】：氮化铝(Al N)是一种新型的应用广泛的功能陶瓷材料,具有良好的热传导性能、电绝缘性及与硅接近的热膨胀系数等优良性质。随着船舶逐渐向智能化、自动化发展,Al N在船舶与海洋工程领域的应用越来越广泛。本文利用等离子体辅助机械力活化法在室温下合成了Al N。与常规的碳热还原法和直接氮化法相比,采用固态有机氮源通过DBDP辅助球磨合成Al N的温度显著降低。本文对三种体系进行普通球磨和DBDP(介质阻挡放电等离子体)辅助球磨的研究,主要包括:(1)研究了以Al+NH3混合物为原料的气-固反应体系,发现NH3虽然化学性质比N2更活泼,但是由于气态氮源存在摩尔量小、与反应物接触不充分等局限性,导致无法在室温下通过DBDP辅助球磨直接制备出Al N。但DBD等离子体产生的高能粒子能有效细化粉体。(2)研究了以N2为氮源,Al+Li OH?H2O混合物为原料的气-固反应体系,发现室温下两种球磨方式只在球磨1 h时,获得极少量的Al N粉末。之后随球磨时间的增加,Al N衍射峰逐渐减弱并消失,这是因为球磨罐内的Al N随球磨的进行发生了水解反应。(3)研究了以Al+DAMN混合物为原料的固-固反应体系,发现随着球磨进行,成功的在室温下直接通过DBDP辅助球磨制备出Al N。得到的Al N转化率随时间的增加而逐渐升高,且DBDP辅助球磨的转化率为高于普通球磨。表明与单纯的机械能作用相比,等离子体与机械能的协同作用更有利于促进反应进行。通过电学诊断发现,在等离子体辅助球磨过程中,得到了密集稳定的强脉冲放电,导致球磨时能够产生大量的高能粒子。对反应过程中各物质官能团的变化进行红外光谱分析,发现Al+DAMN能够合成Al N的主要原因是等离子体产生的高能粒子轰击粉体,使粉体局部产生“电热爆”效应,促进不稳定的DAMN逐渐失去腈基和胺基,这些游离的含氮基团与Al发生反应,合成Al N。对粉体进行热动力学分析,发现DBD产生的高能粒子具有高的热效应、动能及表面溅射和活化作用。能显著提高粉体的活性,降低反应活化能,从而在室温下直接制备出Al N。
[Abstract]:Aluminum nitride (AlN) is a new and widely used functional ceramic material with good thermal conductivity, electrical insulation and thermal expansion coefficient close to silicon. In this paper, the plasma assisted mechanical activation method is used to synthesize Al N at room temperature. Compared with the conventional carbothermal reduction method and direct nitriding method, Al N is synthesized at room temperature. The temperature of DBDP assisted ball milling for the synthesis of Al N from solid organic nitrogen sources has been significantly reduced. In this paper, the general ball milling and DBDP (dielectric barrier discharge plasma) assisted ball milling of three systems have been studied. The gas-solid reaction system using Al NH3 mixture as raw material was studied. It was found that NH3 was more active than N2 in chemical properties, but it was found that because of the small molar amount of gaseous nitrogen source and insufficient contact with reactants, As a result, Al N can not be directly prepared by DBDP assisted ball milling at room temperature, but the high energy particles produced by DBD plasma can effectively refine the powder. In the gas-solid reaction system with H _ 2O mixture as raw material, it was found that only a small amount of Al _ N powder was obtained at room temperature when only one hour of ball milling was used, and then the diffraction peak of Al _ N gradually decreased and disappeared with the increase of ball milling time. This is because the hydrolysis reaction of Al N in the ball mill tank occurred with the ball milling. The solid solid reaction system using Al DAMN mixture as raw material was studied, and it was found that with the ball milling process, AlN was successfully prepared by DBDP assisted ball milling at room temperature. The conversion rate of Al N increased with time, and the conversion rate of DBDP assisted ball mill was higher than that of ordinary ball mill. It was shown that the conversion rate of DBDP assisted ball mill was higher than that of ordinary ball mill. The synergetic effect of plasma and mechanical energy is more favorable to promote the reaction. Through electrical diagnosis, it is found that in the plasma assisted ball milling process, dense and stable strong pulse discharge is obtained. A large number of high energy particles can be produced during ball milling. The changes of functional groups of various substances in the reaction process are analyzed by infrared spectroscopy. It is found that the main reason for the synthesis of Al N by Al DAMN is the bombardment of powder by high energy particles produced by plasma. The local "electrothermal explosion" effect of the powder was induced, and the unstable DAMN gradually lost the nitrile group and the amine group. These free nitrogen-containing groups reacted with Al to synthesize Al N. Thermokinetic analysis of the powder was carried out. It is found that the high energy particles produced by DBD have high thermal effect, kinetic energy, surface sputtering and activation, which can significantly improve the activity of the powder and decrease the activation energy of the reaction, thus the Al N can be prepared directly at room temperature.
【学位授予单位】：集美大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ174.1

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