导　　师： 夏天东

学科专业： 080503

授予学位： 硕士

作　　者： ;

机构地区： 兰州理工大学

摘　　要： 本文从热力学、动力学两方面研究了2Mg+TiO/_2=Ti+2MgO自蔓延高温合成反应的可行性，并且从工艺参数对反应的影响方面研究了2Mg+TiO/_2=Ti+2MgO的反应过程，该研究可以发展成为制各金属钛的一种新方法。 基于热力学理论，对Mg-TiO/_2体系反应的吉布斯自由能、绝热温度、Ti的熔化率以及Mg的气化量进行了理论计算和分析。吉布斯自由能计算表明：反应2Mg+TiO/_2=Ti+2MgO在2242K以下的吉布斯自由能/(ΔG/_T~θ/)都小于零，即反应可以自发进行；通过对Mg-TiO/_2体系的吉布斯自由能的计算可知，在Mg-TiO/_2体系中可能进行生成Ti/_3O/_5、Ti/_2O/_3、TiO等多种低价氧化物的反应，随着温度的升高，单质Ti还原反应趋势下降。另外通过对Al-TiO/_2体系吉布斯自由能的计算得出了与Mg-TiO/_2体系同样的规律。绝热温度的计算表明：随着x的增加，反应/(2+x/)Mg+TiO/_2=Ti+2MgO+xMg的绝热温度逐渐降低，在x＜0.5时绝热温度均大于1800K。Ti的熔化率计算表明：绝热温度曲线上出现的平台是Ti的熔化吸热所致。Mg的气化量计算表明：在反应过程中Mg大量气化，要得到Ti单质，反应中x必须在0.9以上。 基于差热分析和动力学理论，研究了2Mg+TiO/_2=Ti+2MgO的反应过程。从差热曲线上可以看出：反应的放热峰出现在767K～886K之间小于Mg的熔点/(933K/)所以反应为固—固反应；由DTA结果推算动力学参数：活化能E=248.9KJ·mol~/(-1/)，反应级数n=0.55。 结合X射线衍射分析研究工艺参数的影响表明：由于反应过程中Mg大量气化，要使反应2Mg+TiO/_2=Ti+2MgO进行完全，即得到Ti单质，Mg必须过量0.9mol；反应环境的真空度越高，反应生成氧化物的价态越低，反应进行的越完全，越容易得到Ti；压坯压力越大，燃烧产物的孔隙越小，完整性越好，燃烧波速度越高，燃烧温度随压坯压力的增大先升后� In this paper, the feasibility of 2Mg+TiO/_2= Ti+2MgO by SHS was studied from two aspects of thermodynamics, reaction kinetics and the reaction process was studied from the processing parameter, the research could develope a new method of reducing Ti. According to the thermodynamics theories, reaction Gibbs free energy, adiabatic temperature and melting rate in Mg-TiO/_2 system have been theoretically calculated and analyzed. Results of Gibbs free energy calculation showed that the reaction of 2Mg+ TiO/_2= Ti+2MgO would occur below temperature 2242K because its reaction Gibbs free energy was lower than zero; might generate the low valency oxide of Ti: Ti/_3O/_5、 Ti/_2O/_3、 TiO et al, in the Mg-TiO/_2 system and the trend of getting Ti by mean of reducing reaction would descent with temperature raised. Through calculations of the Gibbs free energy in Al-TiO/_2 system, the ruler was the same in Al-TiO/_2 system as in Mg-TiO/_2 system. Result of adiabatic temperature calculation showed that the adiabatic temperature became lower with the increasing of x in /(2+x/)Mg+TiO/_2=Ti+2MgO+xMg, the adiabatic temperatures were over 1800K when the x<0.5. Results of melting rate calculation of Ti showed that the adiabatic temperature plateau was the result of Ti melting endotherm. Results of Mg gasification quantity calculation showed that a great deal of Mg gasified in reaction so x should be over 0.9 in order to get the Ti. Based on Differential Thermal Analysis and kinetic theory, the reaction process was studied. The curve of DTA showed that the reaction exothermal wave was between 767K～886K which was below the melting point of Mg so the reaction was solid-solid mode; The kinetic parameters by DTA results calculation were activation energy E=248.9KJ ? mol~/(-1/), reaction order n=0.55. Results showed that the influence of process parameters with X-ray diffraction analyse: because of the gasification of Mg, Mg would excess 0.9mol in order that the reaction of 2Mg+TiO/_2= Ti+2MgO proceed

关 键 词： 自蔓延高温合成 绝热温度 差热分析 射线衍射

领　　域： [理学] [理学]