气相爆轰合成纳米TiO_2粉末的实验研究

Experimental Study on TiO_2 Nanoparticles Prepared by Gaseous Detonation

以H_2/Air预混气体为爆炸源,在自制爆炸反应管中通过气相爆轰制备纳米TiO_2粉末。探讨了不同初始条件(初始温度25~200℃;H_2/Air混合比0.2~0.8)下管内爆轰压力的变化规律,同时借助XRD和TEM对不同初始温度下爆轰合成及高温煅烧的纳米TiO_2粉末的晶粒尺寸、晶相成分、形貌特征等进行表征。结果表明:以化学当量比预混的H_2/Air为爆炸源时,管末端的爆压最大;随着H_2含量的增加,管末端的爆压最终提高了39.03%,且增长速率先增后减;初始温度的上升使管末端的爆压最终降低了36.86%。气相爆轰合成的纳米TiO_2粉末(锐钛矿和金红石混晶),其晶粒尺寸随初始温度的升高先增后减,且其锐钛矿相含量逐渐减少;爆轰产物在高温煅烧过程中,锐钛矿相向金红石相转变的相变温度在700~900℃左右,且产物晶粒尺寸随煅烧温度的上升而逐渐增加。

Using the premixed H2/Air as explosion source,TiO2 nanoparticles were prepared by gaseous detonation in a self-made explosion reaction tube.The variation law was discussed of the detonation pressure in the tube under different initial conditions（initial temperature of 25200℃and H2/Air mixing ratio of 0.20.8）.Particle size,composition of crystal phase and morphologies of TiO2 nanoparticles synthesized by detonation at different initial temperature and calcinated at high temperature were characterized by means of XRD and TEM.The results show that the end of the explosion reaction tube has the largest detonation pressure when the premixed H2/Air with the chemical equivalent ratio is employed as explosion source.The detonation pressure at the tube end is increased eventually increased by 39.03% with the increase of H2/Air mixing ratio,and the increasing rate firstly increases and then decreases.However,the detonation pressure at the tube end is reduced eventually by 36.86% with the initial environmental temperature increasing.The prepared TiO2 nanoparticles are mixed crystals of anatase and rutile,their grain size increases at first and then decreases with the increase of initial temperature,and the anatase phase is gradually reduced.The phase-transition temperature from anatase to rutile is 700900 ℃ during high temperature calcination of detonation products,and the grain size is gradually increased with the rise of calcination temperature.