干法室温振动制备超微颗粒的理论与应用

Theory and application of preparation of ultrafine grains by dry roller vibration milling at room temperature

采用振动研磨的方法制备超微颗粒的理论研究表明,外力所作的功克服了材料的内聚力使材料发生局部变形,当局部应力超过临界剪切应力时产生断裂口,裂口的形成释放了物料内部的变形能,促使裂纹继续扩展形成新的表面,碰撞过程中振动能量转化为新生颗粒的表面能、热能和化学能.扫描电子显微镜和透射电子显微镜图像显示,研磨过程中固体颗粒于结构薄弱处发生塑性变形直至颗粒破碎,随着研磨时间的增加,颗粒不断细化,粒度分布趋于均匀.X射线衍射分析可见,样品的晶体结构和化学成分均未改变,颗粒细化过程中没有新物相产生.

According to theoretical analysis, when vibration milling is used to prepare ultra-fine grains, the exogenic work leads to the material local deformation. When local stress exceeds critical shearing stress of material, the breakaway points are reached within the material and the inner energy is released, which quicken up the crack growth and form new surfaces. Then vibration energy transforms to heat energy, chemistry energy and surface energy of the new grains in the process of impact. Scanning electron microscope and transmission electron microscope images show that the average diameter of the grains becomes less and less as time consuming and its granularity approach gradually uniform. X-ray diffractmeter results reveal that the lattice parameters, chemical constitution of the nano-particles are the same as raw material and no new phase appears.