固体颗粒的结构演化与机械力化学效应

干法、室温振动研磨制备铝超微颗粒, 分别将研磨2 h, 4 h和8 h的铝粉, 在常温下超声水解得到白色Al(OH)₃胶体, 水解产品经干燥、研磨、焙烧后制备出多孔、片状γ -Al₂O₃纳米颗粒, 粒度分布在30---50 nm之间. 借助于X射线衍射(XRD)分析方法和透射电子显微镜(TEM), 研究固体颗粒在细化过程中的能量转换, 分析颗粒的微结构演化与机械力化学反应的关系, 确定理想的研磨时间. 研究结果表明: 固体颗粒在机械力的作用下产生大量的应变和位错缺陷, 使材料处于亚稳、高能活性状态, 易于诱发机械力化学反应, 在一定条件下晶体的表面能、应变能和层错能相互转化; 研磨2 h的铝颗粒内部, 晶格畸变和位错概率最大, 材料显示出极高的化学反应活性, 在超声波激发下, 储存在材料内部的能量被充分释放, 在较短的时间内, 水解生成Al(OH)₃纳米颗粒.

Structure evolvement of solid particles and mechano-chemical effect

Al ultra-fine grains are prepared by dry roller vibration milling at room temperature.After the ultrasonic hydrolyzing,the Al powders are milled for 2 h,4 h and 8 h,separately,becoming the colloidal Al（OH）3.After the hydrolyzing production are dried, grinded,calcined,the flakyγ-Al₂O₃ nano-particles are obtained,and the particles sizes are in the range from 30 to 50 nm.By X ray diffraction（XRD） analysis method and transmission electron microscope（TEM）,we analyze the energy conversion of solid particles in the vibration milling,and study the relation between the structure evolvement of solid particles and mechano-chemical reaction,in order to ascertain ideal milling time.The research results indicate that the solid particles under the action of mechanical force generate a mass of deformation and dislocation flaws and the material is in metastable high-energy state,which is favorable for inducing mechano-chemical reaction.In certain conditions,the surface energy of crystalloid,strain and dislocation energy could be mutually converted. The odds of lattice distortion and dislocation are maximal for the 2 h-milled Al powders,so the material shows a higher chemical reaction activation.On the ultrasonic agitation,the energy is fully released from the material interior,then Al（OH）₃ nano-particles are prepared in a short time.