【作者】 彭立明；

【导师】 徐匡迪； 毛协民；

【作者基本信息】 上海大学 ， 钢铁冶金， 2000， 博士

【摘要】 电车线是电气化铁路、工矿电机车等用滑接馈电线的总称。国内外的电车线通常采用的是铜及铜合金电车线，在铜电车线材料的研究中，长期以来存在着高强度和高导电率之间的矛盾，这种矛盾甚至贯穿于整个导电材料研究的始终。采用材料复合技术研制导电材料是近年来发展起来的新方法，由于自生复合材料的各向异性和良好的界面复合能力，使其在解决导电材料的轴向强度和导电性的综合性能方面表现出了极大的潜力。如何实现自生复合电车线的连续稳定制备和产业化生产则成为当前自生复合电车线研究的主要方向。本文正是以此为背景，深入研究了自生复合Cu-Cr合金的连续制备过程、工艺特性及电车线的组织与性能，系统地考察了相关的定向连续铸造过程中的工艺参数的交互作用规律，并对工艺参数的实时控制特性和方法进行了探索性研究，以期为自生复合电车线的产业化生产打下基础。 本文提出了通过采用定向连续铸造技术制备自生复合材料的方式来解决电车线材料中强度与导电性兼顾问题的崭新技术路线，深入研究了自生复合Cu-Cr合金通过定向凝固连续铸造方法制备电车线坯的工艺过程及其对材料组织和性能的影响。自生复合Cu-Cr合金在定向连铸之后宏观上具有沿轴向排列的柱状晶组织，微观上保持了与普通定向凝固后相同的组织形态：强化相Cr质点由自由凝固时的弥散分布转化为沿α(Cu)晶界定向排列，其一般特征为初生α(Cu)基体呈柱状，在α晶之间2000年上海大学博士学位论文分布着条状的汉Cr)相和试Cu)+八Cr)共晶体。前者为导电相，后者为强化相，形成两相有序相间的自生复合材料。这样的组织形态在导电材料的强度与导电性上的表现为:强度得到极大提高，而导电性由于定向组织的各向异性而在电流传输方向一「降很小。 考察了电车线铸坯制备标准电车线杆的后续加工性能以及电车线后续加工工艺对自生复合Cu一Cr合金组织及性能的影响。经冷拉拔后的自生复合Cu一C:合金电车线仍基本保持了定向凝固时的组织形态，其抗拉强度有大幅度提高，导电率有所下降，但综合性能明显高于定向连续铸造铸态电车线。定向连续铸造的Cu一C:合金铸态抗拉强度一般在300一35OMPa之间，延伸率约30%~4O%，相对导电率87%~95%，综合性能可达9. 6xl护MP矛%。经冷拉拔变形后抗拉强度可提高到400~4 60MPa之间，相对导电率80%~85%，综合性能可达18.3xl护MPaZ%。软化热处理实验还发现自生复合电车线具有极好的热稳定性;经过3 h 500℃的保温处理，自生复合电车线的综合性能几乎保持不变。 定向连续铸造过程中的稳定的固/液界面位置是连续定向组织材料制备成功的关键因素，本文系统地研究了制备自生复合Cu一Cr合金电车线坯的固/液界面位置条件以及对固/液界面位置的影响因素。自行设计了一套定向连续铸造过程的数值仿真软件，通过该软件可以系统研究定向连铸过程中工艺参数的交互作用规律。数值仿真结果显示，虽然定向连铸的可控制工艺参数多达六个，但固/液界面位置及凝固界面形状主要与冷却趴离、铸型出口温度和牵引速率等三个参数有关，而其他工艺参数影响很小。随着冷却距离、铸型出口温度和牵引速率的增大， 自生复合电车线连续制备过程中工艺参数的交互作用及其控制研究固液界面位置向远离铸型出口的方向移动。 本文还考察r各工艺参数的相互搭配方式对固/液界面位置的影响规律。发现_〔艺参数冷却水温度或冷却水流量在单独作用下，对固/液界面位置的影响均是不显著的，但当考察两者的相互搭配时，影响则是显著的。当冷却水温度为20℃和冷却水流量为7OL/h时，固/液界面位置最接近于铸型出口。 采用人工神经网络技术建立了稳定制备时固/液界面位置及形状因子的预测模型，对于预测任意工艺参数组合下固/液界面位置或形状因子具有较高的精度，为制定定向连续铸造的最佳工艺‘范围提供了很好的指导。 深人研究了定向连铸弓f晶过渡阶段的动态过程，首次提出了过渡阶段牵引速率与凝固界面推进、固/液界面位置变化的匹配技术。分析了引晶过渡阶段的温度场及凝固界面的演化历程对于最终的固/液界面位置的影响特性。固/液界面位置是从开始时位于铸型内部某一深度向铸型外方向迁移。引晶阶段的温度场变化取决于该阶段的凝固界面推进速率与引晶牵引速率的匹配.在相同的稳定工艺参数条件下，过渡阶段的引晶速率采用缓慢加速的方式有利于减小固/液界面位置向铸型外的迁移量，引晶速率加速越缓，迁移量越小。 考察了定向连续铸造过程中固/液界面位置的实时控制特性。选取了冷却距离、铸型出口温度和牵引速率作为控制量，建立了固/液界面位置的简化控制模型。并根据控制要求，构建了以工控机为主的控制系统硬件配置。更多还原

【Abstract】 Contact cable is an important part of the electrical railway system. Copper alloy contact cable is the most common type of cables used as so far. Chronically there exits a contradiction between the requirement of high strength and that of high conductivity during the study of copper contact cable and even this contradiction runs through the research of all conductive materials. Manufacturing the contact cable by material composite technology is a newly developed method in recent years. Due to its anisotropism and excellent ability of interfacial combination, in-situ composite shows a wonderful potential to giving the attention to the strength and the conductivity of conductive materials at one time. The key direction in the current research of in-situ composite contact cable is how to continuously steadily produce it and so to realize the industrialization of it. Just on the consideration of all above, in this dissertation the continuous casting procedure of in-situ composite Cu-Cr alloy and its technological characteristics as well as the structure and properties of contact cable are deeply researched, the interactions among the technical parameters of directional solidification continuous casting (DSCC) process are analyzed, and also the real-time-control characteristics and methods of parameters are discussed. The purpose of all work is to make the foundation of industrialization of in-situ composite contact cable.First, the process of contact cable castings of in-situ composite Cu-Cr alloy by means of DSCC, as well as its effects to contact cable’s structure and properties, is lucubrated in this paper. The in-situcomposite Cu-Cr alloy by DSCC has a feature on macrostructure that columnar grains directionally ranks on the axial direction of the castings, and its microstructure has a general pattern as following: primary a (Cu) crystals are cellular or columnar and strip particles (Cr) and eutectic [ + ] alternately distributes between any two primary (Cu) grains. This forms regularly two-phase-alternation in-situ composite materials among which the (Cu) plays the rule of electricity-conduction while the (Cr) that of strengthening. This type of microstructure results in that the strength of conductive materials is improved well and the conductivity along direction of electricity transmission slightly decreases due to anisotropism character of the material with directional structure.Second, standard contact cable samples are made from in-situ composite Cu-Cr castings and effects of the subsequent process technology of castings on its structure and properties are investigated. Cold-drawn in-situ composite contact cable samples still keep a structure conformation like as-cast structure so that their tensile strength is improved greatly and their electricity conductivity decreases slight but all in all their synthetic properties are obviously higher than those of castings. As-cast in-situ composite Cu-Cr alloy’s tensile strength is about 300~350MPa, elongation rate between 30%~40%, and relative conductivity around 87%~95%, so as to 9.6x106MPa2 % of synthetic property; Cold-drawn contact cable samples’ tensile strength is up to 400~460MPa and relative conductivity down to 80%~85% so that the synthetic property can be up to 18.3xl06MPa2 % maximally. Also it is found with heat-treatment experiments that the in-situ composite contact cable has of excellent thermal stability as following: its synthetic property varies little after 3 h soaking at 500 C.In addition, the forming conditions of the S/L interface locationand the influencing factors on them, during the continuous casting of in-situ composite Cu-Cr contact cable, which is the key for continuously directional solidification structure of materials, are systematically studied. Although DSCC process has 6 controllable technical parameters shown by numerical simulation, the S/L interface location and S/L interface shape-factor are greatly relevant to 3 parameters of all, such as the cooling distance Lc, the mold exit temperature Tm, and the pulling更多还原