纳孔方钴矿热电材料力学行为的分子动力学研究

发布时间：2018-02-03 09:55

本文关键词： 纳孔方钴矿CoSb3 分子动力学力学行为　出处：《武汉理工大学》2015年硕士论文　论文类型：学位论文

【摘要】：热电材料是利用Seebeck效应实现热能与电能之间相互转换的新型功能材料,利用热电材料制作的器件无污染、安全可靠,具有广阔的应用前景。方钴矿CoSb3热电材料是我国以及国际上高度重视研究的热电材料,在方钴矿CoSb3热电材料中引入纳米孔洞可以显著降低材料的热导率从而提高其热电性能,纳孔方钴矿材料被认为是很有应用前景的热电材料,但是纳米孔洞的引入会降低材料的力学性能,从而限制方钴矿材料的工业化应用。鉴于此,本文以纳孔方钴矿热电材料为研究对象,利用课题组前期建立的方钴矿原子间相互作用势函数,发展纳孔方钴矿热电材料单轴拉伸和压缩力学行为的分子动力学方法,分别研究单轴拉伸和压缩应力场下纳孔形状和孔隙率对方钴矿材料本征力学行为的影响规律,从原子尺度上研究并揭示纳孔方钴矿材料单轴拉伸和压缩应力场下的结构破坏机理,探索具备高力学性能纳孔方钴矿材料的孔隙率、纳孔形状的匹配关系,为发展高力学性能的纳孔方钴矿热电材料提供理论指导。纳米柱孔方钴矿CoSb3的力学性能研究结果表明,外部加载条件如温度和应变率对力学性能影响很小,但是孔隙率对拉伸/压缩力学性能影响很大。相对于环境温度和孔隙率,纳米柱孔主宰着单晶CoSb3的缺陷形式,拉伸/压缩力学性能随着孔隙率的增加逐渐降低,弹性模量与孔隙率满足反比例函数关系式。极限应力随着孔隙率的增加线性降低。纳米球孔方钴矿CoSb3力学性能研究结果表明,球孔力学性能优于柱孔CoSb3的力学性能,这主要是由于柱孔CoSb3更多的应力集中区域导致的。随着孔隙率的增加,所有的力学量依次降低。球形纳孔方钴矿CoSb3表现出相同的温度软化效应。这种软化效应随着拉伸应变的增加逐渐加剧。应变率基本对纳米球孔方钴矿CoSb3的拉伸/压缩弹性模量和拉伸/压缩极限应力无影响。
[Abstract]:Thermoelectric material is a new type of functional material which uses Seebeck effect to realize the conversion between heat energy and electric energy. The device made from thermoelectric material has no pollution and is safe and reliable. The CoSb3 thermoelectric material of galactic cobalt ore is a kind of thermoelectric material which is paid great attention to in our country as well as in the world. The introduction of nano-pores into the CoSb3 thermoelectric materials can significantly reduce the thermal conductivity of the materials and improve their thermoelectric properties. The nanoporous galactite materials are considered to be very promising thermoelectric materials. However, the introduction of nano-pores will reduce the mechanical properties of the materials, thus limiting the industrial application of galactic cobalt materials. In view of this, this paper takes the nanocrystallite pyroelectric materials as the research object. The molecular dynamics method of uniaxial tensile and compressive mechanical behavior of nanocrystallite pyroelectric materials was developed by using the potential function of interaction between the atoms of galactic cobalt ores established by our research group. The effect of the shape and porosity of nanpore on the intrinsic mechanical behavior of galactic acid materials under uniaxial tensile and compression stress was studied respectively. In this paper, the failure mechanism of nanocrystallite materials under uniaxial tensile and compressive stress was studied and revealed from atomic scale, and the porosity and the matching relation of nanoporous shape of nanoporous cobalt ore materials with high mechanical properties were explored. It provides theoretical guidance for the development of high mechanical properties nanocrystallite pyroelectric materials. The mechanical properties of nanocrystallite CoSb3 are studied. External loading conditions such as temperature and strain rate have little effect on mechanical properties, but porosity has a great effect on tensile / compressive mechanical properties, compared with ambient temperature and porosity. Nano-columnar pore dominates the defect form of single crystal CoSb3, and the tensile / compressive mechanical properties decrease with the increase of porosity. The relationship between elastic modulus and porosity is inversely proportional. The ultimate stress decreases linearly with the increase of porosity. The results of CoSb3 mechanical properties study show that the ultimate stress decreases linearly with the increase of porosity. The mechanical properties of spherical pore are better than that of columnar pore CoSb3, which is mainly due to the more stress concentration area of CoSb3. All the mechanical quantities decreased in turn. The CoSb3 of spherical nanoporous cobalt ore showed the same temperature softening effect. This softening effect gradually increased with the increase of tensile strain. The tensile / compressive elastic modulus and tensile / compression ultimate stress of oSb3 are not affected.
【学位授予单位】：武汉理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB34

【参考文献】