区熔法制备的藕状多孔铜气孔结构及其压缩性能研究

发布时间：2018-01-03 12:42

本文关键词：区熔法制备的藕状多孔铜气孔结构及其压缩性能研究　出处：《昆明理工大学》2017年硕士论文　论文类型：学位论文

【摘要】：金属-气体共晶定向凝固技术(Gasar)是近年来发展起来的制备多孔金属的新工艺。利用该工艺制备的多孔金属,其内部为沿凝固方向定向排列的圆柱形气孔,结构与莲藕根相似,因此也常被称作藕状多孔金属。藕状多孔金属特殊的孔隙结构使得其具备诸多特殊的性能,在结构材料、功能材料等领域具备重要的应用价值。区域熔炼法能够通过控制其牵引速率来使凝固过程中的凝固速率维持恒定,可制备出气孔分布均匀的藕状多孔金属材料,且在区熔工艺中不需要使用坩埚和铸型,能够避免金属受到污染。本课题采用区域熔炼法制备了不同结构的藕状多孔铜,分析了氢气压力和牵引速率两个工艺参数对藕状多孔铜气孔结构和形貌的影响规律。结果表明:在氢气压力为0.1MPa至0.4MPa内,随着氢气压力的增大,气孔率呈先增大后减小的趋势,在氢气压力为0.2MPa时,气孔率最大,为19.52%;平均气孔直径由0.89mm减小至0.42mm,气孔直径的分布范围逐渐变窄,气孔尺寸的均匀性提高;气孔数密度由 27.77/(100mm2)增加至 94.79/(100mm2)。在气体总压为0.4MPa,而氢气分压为0至0.4MPa内的情况下,随着氢气分压的增大,气孔率由0增加至16.88%;平均气孔直径由0增大至0.42mm,气孔直径的分布范围因氢气分压的增大而变宽,气孔尺寸的均匀性降低;孔数密度呈现先减小后增大的趋势,其中,在氢气分压为0.3MPa时,气孔数密度最小,为62.79/(100mm2)。氢气压力为0.2MPa时,随牵引速率由10mm·min-1增大至30mm·min-1,气孔率由9.88%逐渐增大至23.44%;平均气孔直径由0.81mm减小至0.64mm;气孔数密度由16.06/(100mm2)逐渐增大至57.88/(100mm2);牵引速率对气孔直径分布并没有太大的影响。在室温环境下测试了藕状多孔铜的压缩性能,分析了气孔结构参数(气孔率及平均气孔直径)对压缩性能的影响规律,并讨论了藕状多孔铜的压缩变形方式。结果表明:随气孔率由5.61%增加至24.11%,区熔藕状多孔铜的压缩应力-应变曲线的斜率逐渐减小,其压缩屈服强度由25.63MPa逐渐减小至12.61MPa,单位体积吸收能由39.53MJ·m-3逐渐减小至29.38MJ.m-3,杨氏模量由2.76Gpa逐渐减小至1.1OGPa,密实化初始应变值由40.11%增大至44.76%,抵抗塑性变形的能力随气孔率的增大而降低。在气孔率为13%情况下,平均气孔直径由0.52mm增大至0.61mm后,区熔藕状多孔铜的压缩屈服强度、密实化初始应变值、单位体积吸收能及杨氏模量都有一定程度的增大,抵抗塑性变形的能力提高;藕状多孔铜在压缩变形过程中的主要变形方式为气孔孔壁的弯曲变形和折叠变形。
[Abstract]:Directional solidification of metal gas eutectic (Gasar) is a new process for the preparation of porous metal developed in recent years. The preparation process of porous metal, its internal cylindrical pores along the solidification direction, and structure of lotus root is similar, so it is often called the lotus type porous metal pore structure. Lotus type porous metal special makes it have many special properties in structural materials, have important application value in the field of functional materials. The zone melting method to maintain a constant through the traction speed to control the solidification rate during the solidification process, can be prepared by Lotus type porous metal material uniform pore size distribution, and do not need to the use of crucible and mold in the zone melting process, to avoid metal contamination. The zone melting of lotus type porous copper with different structure were prepared, analyzed the hydrogen pressure and pulling rate Influence of two parameters on the lotus type porous copper pore structure and morphology. The results showed that: in the hydrogen pressure of 0.1MPa to 0.4MPa, with the increase of hydrogen pressure, the porosity increases, the hydrogen pressure is 0.2MPa, the porosity is 19.52%, the average pore diameter by 0.89mm; reduced to 0.42mm, the distribution range of the pore diameter gradually narrowed, the uniformity of pore size increases; the pore number density by 27.77/ (100mm2) increased to 94.79/ (100mm2). The total gas pressure was 0.4MPa, while the hydrogen partial pressure of 0 to 0.4MPa in the case, with the increase of hydrogen pressure, the porosity by 0 increased to 16.88%; the average pore diameter increases from 0 to 0.42mm, the distribution range of the pore diameter increases with the partial pressure of hydrogen increaecs uniformity of pore size decreased; pore number density decreased first and then increased, which, in the hydrogen partial pressure is 0.3MP A, the pore number density minimum, 62.79/ (100mm2). The hydrogen pressure is 0.2MPa, with the traction rate increased to 30mm by 10mm - min-1 - min-1, the porosity increases from 9.88% to 23.44%; the average pore diameter decreased from 0.81mm to 0.64mm; the pore number density by 16.06/ (100mm2) to 57.88/ (increased gradually 100mm2); traction rate on the pore diameter distribution is not significantly affected. The compression performance of lotus type porous copper test at room temperature, analysis of pore structure parameters (porosity and average pore diameter) influence of compression performance, and discusses the way of compression deformation of lotus type porous copper. The results show that as the porosity increases from 5.61% to 24.11%, zone melting of lotus type porous copper compression slope of stress - strain curve decreases, the compressive yield strength by 25.63MPa gradually reduced to 12.61MPa, per unit volume of absorbed energy by 39.53MJ - M-3 gradually reduced to 29. 38MJ.m-3, Young's modulus gradually from 2.76Gpa to 1.1OGPa, the density of the initial strain value increases from 40.11% to 44.76%, increasing the ability to resist plastic deformation with the porosity decreases. The porosity was 13% cases, the average pore diameter increased from 0.52mm to 0.61mm after zone melting of lotus type porous copper compression yield strength densification, initial strain, energy absorption per unit volume and modulus are increased to a certain extent, improve the capacity of plastic deformation resistance; lotus type porous copper in compression deformation is the main deformation ways in the process of bending deformation of hole wall and folding deformation.

【学位授予单位】：昆明理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG146.11;TB383.4

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