【作者】 杨亮；

【导师】 赵剑峰；

【作者基本信息】 南京航空航天大学 ， 机械制造及其自动化， 2009， 硕士

【摘要】 激光作为一种热源,由于其具有的瞬态非平衡能量输出机制以及作用在材料时的超快加热效应,近几年在纳米材料的制备中已有所应用。当激光照射材料时,在激光作用的三维空间内,激光能量呈现出一定的梯度分布,为材料的合成提供了条件。本文以激光为热源,以SiC纳米颗粒材料为前驱体,进行了激光照射下SiC纳米颗粒原位生长晶须的试验,探索SiC晶须在激光照射下稳定生长的条件及其生长过程。所完成的工作主要有:1.研究SiC晶须的生长阶段,分析激光照射原位生成晶须的机理和传质机制。2.从晶体生长动力学角度对晶须生长的过程进行分析,同时分析了二次成核的生长部位及方向。3.采用被照射表面与光斑垂直的方式进行SiC纳米颗粒激光照射试验。对样品进行扫描电镜分析,探索晶须稳定生长的条件。4.针对采用不同粘结剂样品生成的晶须,分析激光能量密度对晶须形貌和数量的影响。更多还原

【Abstract】 Laser, as a kind of heat resource, had been used to synthesize nano- materials in the past years because of its instant nonequilibrium output of energy and its speedy heating capability. Because the energy density of laser taken on the gradient distribution in the three dimensional space, so that the abundant conditions to synthesize materials can be created.In-situ growth of SiC nano-whiskers by direct laser irradiation on SiC nano-particles was investigated in this paper. Steady growth conditions and growth process of SiC whiskers by laser irradiation were researched. The main work accomplished and conclusions got are presented as follows:1. Growth stage of SiC whisker was studied. The mechanism and mass transfer mechanism of in-situ growth of SiC whisker by laser irradiation were analyzed.2. Growth process of whisker was analyzed in terms of crystal growth kinetics. And the growth location and direction of secondary nucleation were researched.3. The experiment of laser irradiation was made out with the method that the laser and irradiating surface are upright. The microstructures of the sample prepared by laser irradiation were studied in detail with scanning electron microscopy. The stable growth conditions of whisker were studied.4. According to whisker in samples with different blinders, the effect of laser energy density on SiC whisker morphologies and quantities was analyzed.更多还原