基于铝热还原—电磁铸造法制备铜铬合金中夹杂物的调控研究

发布时间：2018-06-19 13:31

本文选题：铝热还原-电磁铸造 + 铜铬合金　；参考：《东北大学》2011年硕士论文

【摘要】：CuCr合金可以广泛应用于集成电路的引线框、各种电极、电触头、高强度导线等要求高导电性、高强度的领域,是一种具有广泛应用前景的大功率、高压触头材料。传统的粉末冶金法、熔渗法以及真空电弧熔炼法制备CuCr都存在着生产成本高,工艺复杂,成品率低等缺陷,尤其是在制备大尺寸合金铸锭方面存在困难。针对这一现象,课题组提出基于铝热还原电渣重熔法制备铜铬合金的新工艺,先后获得相关发明专利2项。前期研究表明：铝热还原-电磁铸造法直接制备的铜铬合金中存在气孔以及氧化物夹杂等缺陷,本文将对铝热-电磁铸造法制备的合金中夹杂物赋存形态、分布规律以及气孔等微观缺陷进行系统分析,为电渣精炼工艺选择提供理论依据。首先,通过热力学计算得出铝热反应在不同温度下的△Gθ、△G和△H值,确定最高反应温度及热效应。计算结果表明,体系反应的绝热温度为2848K,而且反应的吉布斯自由能变很负,故而以铝作还原剂在理论上是可行的。采用差热分析研究了CuO-Cr2O3-A1体系的动力学,结果表明：反应表观活化能Ea=151.272kJ/mol,反应级数n=2.48,反应动力学方程为：da/dT=0.2464×105e-151272/RT(1-α)2.48。其次,采用SEM、能谱分析技术及金相显微镜对合金进行了表征,分析了在不同工艺条件下制备的合金中夹杂物赋存状态及微观结构缺陷。结果表明：合金中存在富铜区、富铬区以及夹杂物区三个明显的区域,夹杂物主要以气孔和A1203相形式存在,多分布在富铜相区以及富铜相与富铬相界面处。然后,采用XRD技术对熔炼渣及合金相组成进行表征。结果表明：熔炼渣主要由A1203相以及少量的金属Cr相组成,合金主要有Cu相、Cr相和少量A1203夹杂相组成。最后,采用金相显微镜及image图像处理技术对合金中气孔及夹杂物分布规律进行了系统研究。结果表明：电磁搅拌和强化水冷均能减少气孔率。其中,水冷强度加强后合金中的气孔能减少18%,采用铜模浇铸可使Cr粒子细化,添加适量的Na3A1F6、CaF2、CaO、发热剂均能有效地减少合金中夹杂物含量。
[Abstract]:CuCr alloy can be widely used in the field of lead frame, various electrodes, electrical contacts, high strength conductors and so on. CuCr alloy is a kind of high power and high voltage contact material with wide application prospect. The traditional methods of powder metallurgy, infiltration and vacuum arc melting have many disadvantages, such as high production cost, complex process, low yield, etc. Especially, it is difficult to prepare large size alloy ingot. In view of this phenomenon, a new process for the preparation of copper-chromium alloy based on aluminothermic reduction electroslag remelting method was put forward, and two patents were obtained. Previous studies show that there are defects such as porosity and oxide inclusions in the Cu-Cr alloy prepared directly by aluminothermic reduction-electromagnetic casting. In this paper, the inclusions in the alloy prepared by aluminothermic-electromagnetic casting are studied. The distribution law and microcosmic defects such as porosity were systematically analyzed, which provided the theoretical basis for the selection of electroslag refining process. Firstly, the G 胃, G and H values of the thermal-thermal reaction at different temperatures are obtained by thermodynamic calculation, and the maximum reaction temperature and thermal effect are determined. The calculated results show that the adiabatic temperature of the reaction is 2848Kand the Gibbs free energy of the reaction becomes very negative, so it is theoretically feasible to use aluminum as the reductant. The kinetics of CuO-Cr2O3-A1 system was studied by differential thermal analysis. The results showed that the apparent activation energy of the reaction was 151.272 kJ / mol, the reaction order was nu 2.48, and the kinetic equation of the reaction was: 0. 2464 脳 105e-151272 / RT1-伪 2.48. Secondly, the alloy was characterized by means of SEM, EDS and metallographic microscope. The existing state of inclusions and microstructure defects in the alloys prepared under different technological conditions were analyzed. The results show that there are three obvious regions in the alloy, such as copper-rich zone, chromium-rich zone and inclusion zone. The inclusions mainly exist in the form of porosity and A1203 phase, and are mainly distributed in the copper-rich phase region and the interface between copper-rich phase and chromium-rich phase. Then, XRD technique was used to characterize the composition of slag and alloy. The results show that the slag mainly consists of A1203 phase and a small amount of metallic Cr phase, and the alloy mainly consists of Cu phase Cr phase and a small amount of A1203 inclusion phase. Finally, the distribution of pores and inclusions in the alloy was systematically studied by metallographic microscope and image processing technology. The results show that both electromagnetic stirring and enhanced water cooling can reduce the porosity. The porosity in the alloy can be reduced by 18% after the strengthening of water cooling strength. The Cr particles can be refined by copper mold casting. Adding appropriate amount of Na _ 3A _ 1F _ 6 and CaF _ 2 Cao can effectively reduce the content of inclusions in the alloy by adding appropriate amount of Na _ 3A _ 1F _ 6 and CaF _ 2CaO.
【学位授予单位】：东北大学
【学位级别】：硕士
【学位授予年份】：2011
【分类号】：TG291

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