旋转磁场对纯铜凝固组织影响研究
时间:2019-10-17 20:51 来源:毕业论文 作者:毕业论文 点击:次
| 摘要旋转磁场对纯铜凝固组织的细化有着显著的作用。 利用旋转磁场控制纯铜凝固过程，以获得均匀细小的等轴晶，简化了后续工艺。本实验采用电动机定子和调压变阻器自制了一套旋转磁场装置来研究旋转磁场工艺参数对纯铜凝固组织的影响。选取的工艺参数有浇注温度、磁场强度、搅拌时间。实验结果表明：旋转磁场主要通过与金属液流相互作用引起强烈的旋流而产生搅拌作用来影响纯铜的温度场与溶质场的分布，在金属液凝固过程中，磁场力打碎树枝状晶，形成了更多的晶核，故能够显著细化纯铜组织。随旋转磁场强度增大，晶粒细化效果增加，励磁电压为 180V 时，晶粒细化效果最佳。在浇注温度和搅拌时间一定的情况下，旋转磁场的励磁电压的增大，对纯铜组织中心等轴晶的细化作用有显著的增强，纯铜组织硬度有显著的提高，但旋转磁场的励磁电压过大会产生涡流，带动小颗粒聚集在一起,从而会聚集合并生长成大的晶粒,所以晶粒变得粗大；在旋转磁场强度和浇注温度一定的情况下，纯铜熔液在磁场中搅拌的时间越长，纯铜组织越均匀，晶粒越细小且硬度越大，最佳的搅拌时间为 17 秒。 41099 毕业论文关键词：旋转磁场；搅拌时间；磁场强度；纯铜 Effect of rotating magnetic field on pure copper solidification structure Abstract Refinement of the rotating magnetic field on solidification structure of pure copper plays a significant role. Using a rotational magnetic field during solidification of pure copper to obtain uniform fine equiaxed simplifies follow-up process. This experiment used motor stator and voltage rheostat is made by a rotating magnetic field to a rotating magnetic field effect of process parameters on solidification structure of pure copper. Select the process parameters temperature, magnetic field strength and time. Experimental results show that the rotating magnetic field, mainly through intense interaction between liquid metal flow and swirling and stirring to affect the temperature of pure copper and solute distribution during solidification of liquid metal, magnetic forces broke the dendritic crystals, forming more nucleation and organization capable of refined copper. With the rotating magnetic field strength is increased, grain refinement effects of increasing excitation voltage of 180V, grain works best. In pouring temperature and mixing time must of situation Xia, rotating magnetic field of Reed magnetic voltage of increases, on pure copper organization Center, axis crystal of refinement role has significantly of enhanced, pure copper organization hardness has significantly of improve, but rotating magnetic field of Reed magnetic voltage had Assembly produced Eddy, led small particles gathered in with, to will gathered merged growth into big of grain, so grain became coarse; in rotating magnetic field strength and pouring temperature must of situation Xia, pure copper melt liquid in magnetic field in the mixing of time more long, pure copper organization more uniform, The finer grain size and hardness, optimum mixing time was 17 seconds. Key words: rotating magnetic field; mixing time;magnetic field strength;pure copper 目录 1.前言.1 1.1旋转磁场简介.1 1.2旋转磁场的基本原理.1 1.3旋转磁场的产生.1 1.4旋转磁场对金属凝固组织的影响.1 1.4.1旋转磁场对Al-Cu合金凝固组织的影响1 1.4.2旋转磁场对Sn-Bi合金凝固组织的影响.2 1.4.3旋转磁场对Pb-Sn合金凝固组织的影响.2 1.5高速铁路接触线的研究进展.2 1.5.1接触线的种类及性能特点2 1.5.2接触线的生产工艺3 1.5.3接触线的发展方向3 1.6选题的目的和意义.4 1.7课题研究的内容和目标.4 1.7.1研究内容.4 1.7.2研究目标.4 2.实验.5 (责任编辑：qin) |