摘要
铜及铜合金以其良好的导电导热性能,被广泛用于电器电子器件中,随着电子技术及计算机信息技术的迅猛发展,对材料也提出了更高的要求,不仅要求材料具有良好的导电性、而且还应具有较高的强度和软化温度,但铜合金的强度越高电导率就会相应的越低。因此如何解决两者之间的矛盾就成了研究重点。本文采用高能机械球磨-冷压制坯-高温固相烧结-热挤压方法制备出了强度及电导率均较高的铜基复合材料。
本研究采用的实验方法:高能球磨混合2h的Al_2O_3-WC/Cu复合粉于包套中在一定压力下冷压成形;并对冷压坯进行真空高温固相烧结;对已制得的烧结坯进行了热挤压试验研究;通过挤压后Al_2O_3-WC/Cu复合材料试样的拉伸试验,研究了材料的力学性能;此外,还测得了挤压后不同成分的Al_2O_3-WC/Cu复合材料的电导率及软化温度。本文重点研究了以下内容:
高能球磨工艺:研究了WC-Al_2O_3/Cu复合粉形貌随球磨时间的变化规律,并得到了增强相WC和Al_2O_3颗粒弥散分布于铜基体中的最佳球磨时间。
压制性能的研究:研究了5wt%WC-1wt%Al_2O_3/Cu复合粉的压制性能,并得到了压制粉末的压制特性曲线。此外还研究了球磨时间对5wt%WC-1wt%Al_2O_3/Cu复合粉压坯的硬度和相对密度的影响,得出在相同压力下,随着球磨时间的延长,压坯的硬度不断增加,而相对密度却成减小的趋势。
热挤压工艺:对材料进行了包套挤压,坯料在14.8的挤压比下,致密度可达理论密度的94%以上。通过对挤压后WC-Al_2O_3/Cu试样的拉伸试验,研究了影响复合材料抗拉强度、延伸率的因素。并通过对拉伸件断口的观察分析其断裂行为。
电性能及软化温度的研究,测得已制备铜基复合材料的电导率及软化温度并对影响它们的因素进行了分析。
Copper and copper alloy are widely used in electrical and electronic devices because of excellent thermal conductivity properties. As the rapid development of electronic technology and computer information technology, we need materials with not only good conductivity, but also high strength and high softening temperature. But the improvement of copper’s strength is at the expense of its conductivity. So how to solve the contradiction between the strength and conductivity is the research focus. And we prepare copper-based composite materials with high strength and conductivity via the process of high-energy mechanical ball milling, cold pressing of billet, and solid state sintering with high temperature, high-temperature hydrostatic extrusion.
Experimental methods: Firstly, the Al_2O_3-WC/Cu composite powder with 2 hours’high-energy mechanical ball milling is cold-press formed under a certain pressure in the sheath. Then we finish the vacuum high-temperature solid-state sintering to get the sintered billet with higher density. Thirdly, we study on the high-temperature hydrostatic extrusion of four different compositions to improve the density of materials and optimization of material structure. Fourthly, we finish the research on the material’s mechanical properties via the tensile test on Al_2O_3-WC/Cu, which has experienced the process of extrusion. Finally, it comes to the test of conductivity and softening temperature on Al_2O_3-WC/Cu of different composite. In the paper, I focus on the following content.
High-energy ball milling process: we conduct the research on variation of composite powder’s morphology with milling time, and has obtained the best milling time of reinforced phase (WC& Al_2O_3) dispersed in copper.
Suppression characteristics: we study on the suppression characteristics of 5wt% WC-1wt% Al_2O_3-WC/Cu composite powder, and have obtained the suppression characteristic curve. In addition, we do research on the effect of milling time on relative density of 5wt% WC-1wt% Al_2O_3-WC/Cu composite powder, and then we find that the relative density of powder is in the trend of decreasing with the extension of milling time at the presupposition of the same pressure. High-temperature hydrostatic extrusion: Through the extrusion, we draw a conclusion that if the billets are extruded at the extrusion ratio of 11.1, the density will be up to 94% of theoretical density. By the tensile test on Al_2O_3-WC/Cu which has experienced the process of extrusion, we study the mechanical properties of copper-based composite materials in four different compositions, revealing composition’s influence on tensile strength and elongation rate. In addition, we have studied the tensile behavior of copper-based composite materials in four different compositions through observation of the tensile fracture.
Electrical properties and softening temperature: we conduct test on electrical properties and softening temperature of copper-based composite materials in four different compositions and obtain composition’s influence on material’s properties.
引文
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