电场对TiO_2-C-Al系燃烧合成过程的影响

Effect of an external electric field on the combustion synthesis process of TiO_2-C-Al system

以3TiO2+3C+(4+x)Al反应体系为对象,直接燃烧合成致密的TiC-Al2O3-Al复合材料。着重研究了电场对该体系燃烧合成过程的影响。结果表明:外加电场的焦耳热效应可提高体系的绝热燃烧温度,从而突破燃烧合成反应的热力学限制;电场可改变体系的燃烧合成反应的模式;随着电场强度的增加,自蔓延燃烧温度和速度均提高,而合成材料组织中Al2O3和TiC晶粒尺寸逐渐减小;当体系中过余Al量x为14 mol、外加电场强度E为25 V/cm时,可直接燃烧合成相对致密性为92.5%的TiC-Al2O3-Al复合材料,且合成的Al2O3和TiC晶粒尺寸细小(0.2-1.0μm),在金属Al中分布均匀。

Taking 3TiO2＋3C＋（4＋x）Al as a reaction system, a dense TiC-Al2O3-Al composite was directly prepared. The effect of electric-field on the combustion synthesis process of the system was systematically investigated. The results show that the imposition of an external electric field can improve the adiabatic temperature of the reactive system and induce its self-sustaining combustion synthesis process. The electric field also can change the combustion modes of the system. With an increase of the field strength, both the combustion temperature and the self-propagating wave velocity are increased obviously, while the grain size of the in-situ synthesized TiC and Al2O3 particles is decreased significantly. Under the conditions of the AI residual a： being 14 mol in the system and the electric field strength E being 25 V/cm, a dense TiC-Al2O3-Al composite with a relative density of 92.5 % can be successfully fabricated, in which TiC and Al2O3 particles have a fine size of 0.2-1.0 mm, and distribute uniformly in metal Al.