Al纳米颗粒熔化和烧结过程的分子动力学模拟

MOLECULAR DYNAMICS OF THE MELTING AND SINTERING OF THE ALUMINUM NANOPARTICLES

何孟哲

11749279

硕士

机械制造及其自动化

融亦鸣

2019-05-30

2019-06-28

哈尔滨工业大学

深圳

微纳尺度的金属结构在微纳机电系统、微纳传感器等方面有着巨大的应用前景，现有的加工技术在复杂的微纳三维结构尤其是高深宽比结构的加工方面还面临着巨大的挑战，金属增材制造技术以其一体化成型、可以加工任意复杂结构的特点有望突破这一瓶颈。然而由于金属纳米颗粒的分散性差，比表面积大、极易被氧化且熔点比宏观块体材料的熔点低等特性，无法使用现有的金属增材制造技术进行加工。随着各种材料和各种形状的金属纳米颗粒不断被加工出来，人们对金属纳米颗粒的性质的研究也越来越多。由于实验成本高，设计复杂且不易操作，国内外学者广泛采用分子动力学模拟的手段研究了金属纳米颗粒的尺寸效应、烧结过程以及壳核纳米含能材料在激光照射下的放热自维持反应过程。计算结果与实验值的吻合很好的证明了分子动力学进行模拟分析的可靠性，同时，分子动力学还可以提供实验中难以观测到的现象，对实验具有一定的指导意义。本文以Al纳米颗粒为研究对象，用分子动力学方法探究了Al纳米颗粒的熔点及其熔点与其尺寸之间的关系，并且研究了空穴的存在对金属纳米颗粒熔点的影响以及空穴在熔化过程中的形貌变化，同时还研究了两颗Al纳米颗粒在室温下和线性升温的条件下的烧结过程。发现了Al纳米颗粒的熔点与其所包含原子数之间的线性关系，Al纳米颗粒在熔化过程中从表面到核心逐渐熔化的机制。以及两颗Al纳米颗粒的固态粘结机制和不同升温速率对烧结温度影响，对于实现微纳尺度的金属增材制造提供了一定的参考。

Micro/nano scale metal structures have great prospects application in micro/nano electromechanical systems, micro-nano sensors and other fields. The existing technologies are facing enormous challenges in the manufacture of complex micro-nano three-dimensional structures, especially when the ratio of the depth and width of the structures is high. Metal additive manufacturing technology is expected to break through this restriction. However, due to the poor dispersion of metal nanoparticles, large specific surface area, easy to be oxidized and lower melting point compared with macro-bulk materials, it is impossible to use the existing metal additive manufacturing technology.With the metal nanoparticles of various shapes and various materials are produced succesfully, more and more people have studied the properties of metal nanoparticles. Because of the high cost of experiment, complex to design and difficult to operation, scholars all over the world widely used molecular dynamics simulation to study the size effect of metal nanoparticles, the sintering process and the exothermic self-sustaining reaction process of shell-core energetic materials under laser irradiation. The calculated results are in good agreement with the experimental data, which proves the reliability of the simulation analysis of molecular dynamics. At the same time, molecular dynamics can also observe phenomena which are difficult to be observed in the experiment, which has a guidance for the experiment.In this paper, the melting point of Al nanoparticles and the relationship between the melting point and its size were investigated by molecular dynamics. The effect of the existence of holes on the melting point of metal nanoparticles and the morphology change of holes in the melting process were also studied. The sintering process of two Al nanoparticles at room temperature and linear heating were also studied. The linear relationship between the melting point and the number of atoms contained in Al nanoparticles was found, and the mechanism of gradual melting of Al nanoparticles from the surface to the core during the melting process was found. Besides, the mechanism of bonding of two Al nanoparticles both in the room temperature and during the linear heating were also studied. It provides some reference for realizing micro-and nano-scale fabrication of metal additives.

Al纳米颗粒 分子动力学 熔点 空穴 烧结

aluminum nanoparticles molecular dynamics melting point pore sintering

中文

联合培养

南方科技大学

何孟哲. Al纳米颗粒熔化和烧结过程的分子动力学模拟[D]. 深圳. 哈尔滨工业大学,2019.