【作者】 初晓辉；

【导师】 田宗军；

【作者基本信息】 南京航空航天大学 ， 机械制造及其自动化， 2008， 硕士

【摘要】 多孔金属材料或泡沫金属是80年代后期迅速发展起来的一种新型工程材料,其内部具有大量宏观孔洞结构,在消声、减震、分离工程、屏蔽防护等一些高技术领域获得了应用。当前泡沫金属生产工艺主要是烧结、铸造、电沉积方法,这些方法都是前期利用发泡剂帮助金属形成多孔形状,然后利用发泡剂的低熔点或者高温挥发性能在一定温度下将其去除,最终形成泡沫状金属。根据电沉积理论和实践的进展,如果控制各种工艺参数使整个电沉积过程远离平衡态,可以实现枝状晶的大规模生长,现在考虑使用该方法实现泡沫金属的无发泡剂生长,相信这种密枝晶结构可以产生不同于以往的类旋转长条的复杂孔隙,为制备泡沫金属提供一种新的工艺方法。本文采用喷射电沉积的方法进行枝状晶生长成型的试验研究,对该工艺进行试验探索,利用该方法直接制备泡沫金属多孔材料,并对试验结果进行了性能测试。所做工作如下:1.分析枝状晶生长所必需的工艺条件和工艺参数区间,然后进行参数分组细化进行试验,总结每种参数对枝状晶生长的影响规律。本文分别讨论了不同电流、电解液流量、溶液配方、喷头与阴极的距离、电沉积时间、喷头形状等工艺参数下的沉积产物形貌,还讨论了喷头移动后电沉积的效果,对各种参数变化下沉积产物形貌的变化趋势进行了总结。2.使用软件对试验结果进行进一步分析,分析其分形维数,考察枝状晶分枝生长趋势是否强盛,测算枝晶横截面的孔隙率,考察试样各个界面的均匀程度,并且通过对这两个参数的变化趋势进行分析,总结枝晶整个生长过程的规律;随后进行了喷射区域的流场、电场模拟分析,然后结合传统电沉积理论,解释了一些本工艺条件下特有的试样特征。3.对试验结果进行了力学和电学性能测试,并将测试结果与其他工艺的典型数据曲线进行了比较。更多还原

【Abstract】 Foamed metal or porous materials were developed at the end of the 80’s. They have excellent physical properties, especially in damping areas, so they are widely used for noise elimination, vibration insulation, electromagnetic screening and so forth. Up to now, the main methods of manufacturing those materials are process like sintering, special found and electrodepositing. Those methods all make use of the foaming agent which could create holes and hollow structures in the metal. According to the theory of electrodiposition, the process far away from the balance could give birth to a special structure named dendritic crystal, using this phenomenon could help us to produce foamed structured metals directly without foaming agent. It must be different from the original foamed metals in structure and faculty.Electrodepositing methods are used to research the rules of dendritic growth in a large area, works are be doing to be familiar with the rules of these process in order to get foamed metal shaped directly by this way. Then the results of the process are tested in its performance in some areas. Here is the specific statement:1. Organizing experiments to find out the rule of the process is the subject’s first job, a large scope of parameters are changed to find how to make the dendritic growth more healthy and plump, the current, fluid flux, thickness of Ni+, the distance from the nozzle and electrode, shape and move of nozzle, the time are all taken into consideration. Pictures of the results are made and the variation directions of the samples are analyzed, after that procedure, the influence of these given technological conditions to the electrodeposition process could be found out. And then different conditions’results are compared together, the theory and the explanation of the results are improve after that process.2. Further analysis are made in the electrodepositing results, fractal dimensions are calculated to take value of the degree of branching by using a software which could show if the process is prosperous, the porosity is also measured to see how much it fits into the request of foam metals. The trends of the parameters transformation are also analyzed. At last, analysis and simulation of the electrical field and flow field are made respectively which could explain some special phenomenon in the experiments.3. The results’performance in electricity and mechanics are measured and then comparison between the new ones and the original ones are made.更多还原