Heat transfer, fluid transport and mechanical properties of porous copper manufactured by lost carbonate sintering
Heat transfer, fluid transport and mechanical properties of porous copper manufactured by lost carbonate sintering
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消失碳酸盐烧结多孔铜的传热、流体传输和力学性能
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发表时间：
2013
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通讯作者：
Z. Xiao
中科院分区：
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作者：
Z. Xiao
在过去的几十年里，多孔金属由于其独特的物理和结构特性以及从轻质结构、过滤、能量和声音吸收到热管理和电磁屏蔽的许多潜在应用而在工业中受到越来越多的关注。在热力应用中，高能耗机组对传热性能的要求越来越高。多孔铜是这些应用的理想选择，因为它的高比强度，优良的导热性和高表面积。消失模碳酸盐烧结（LCS）法是一种高效且简单的制造工艺，可生产具有大范围孔隙率、各种孔径和孔形状的多孔铜。
本研究的主要目的是探讨LCS法制备的多孔铜的热传、流体传输及机械性质。研究了不同孔隙率/相对密度、铜颗粒尺寸、孔径、孔形状和组合结构的多孔金属试样的渗透率、导热系数、传热系数和力学性能。
利用自制的渗透率测定装置研究了孔隙结构对渗透率的影响。结果表明，LCS多孔铜的压降符合Forchheimer-extended Darcy方程。渗透率随孔隙度和铜颗粒尺寸的增大而增大，随孔隙尺寸的增大而减小。通过引入LCS多孔金属的弯曲度，修正的Carman-Konezy关系可以很好地预测单层和双层结构的渗透率。
LCS多孔铜的热导率随相对密度和孔径的增大而增大，随铜颗粒尺寸的增大而减小。在孔隙率一定的情况下，导热系数随铜颗粒与孔隙尺寸比的增大而减小。建立了描述这种关系的经验方程。
测量了大量样品的传热系数。与空通道相比，多孔铜的引入使传热系数提高了2 ~ 10倍。孔隙率低、孔径大的样品表现出较高的传热系数。在给定的孔径下，对于良好的传热性能，存在一个最佳的孔隙率范围。LCS双层多孔铜的传热系数对层的排列顺序很敏感。提出了一种分段模型来预测多层结构的传热系数，预测结果与实验结果吻合较好。
通过压缩、弯曲和拉伸试验研究了微细铜颗粒制备LCS多孔铜的力学性能。机械强度和表观模量随孔隙率的增加而降低。孔径较大的多孔铜试样具有较好的力学性能。采用扩展的Mori-Tanaka模型对弹性模量进行了预测，预测结果与实验数据吻合较好。
Over the last few decades, porous metals have received a growing interest in industry due to their unique physical and structural properties and many potential applications ranging from light weight structure, filtration, energy and sound absorption to thermal management and electromagnetic shielding. In thermal applications, high energy consumption units demand higher and higher heat transfer performance. Porous copper is an ideal option for these applications due to its high specific strength, excellent thermal conductivity and high surface area. The Lost Carbonate Sintering (LCS) method is an efficient and simple manufacturing process to produce porous copper with a large range of porosity, various pore sizes and pore shapes.
The main objective of this study is to investigate the heat transfer, fluid transport and mechanical properties of porous copper fabricated by the LCS method. The permeability, thermal conductivity, heat transfer coefficient and mechanical properties were studied on a number of porous metal specimens with different porosities/relative densities, copper particle sizes, pore sizes, pore shapes and combinatorial structures.
A purpose-built apparatus was used to study the effects of pore structure on permeability. The results showed that pressure drop of LCS porous copper fits well with the Forchheimer-extended Darcy equation. The permeability increased with porosity and copper particle size, but decreased with pore size. The permeability can be predicted well using the modified Carman-Konezy relationship by introducing the tortuosity of LCS porous metal for both single and double layer structures.
The thermal conductivity of LCS porous copper increased with relative density and pore size, but decreased with copper particle size. The thermal conductivity decreased with the size ratio between copper particle and pore at any given porosity. An empirical equation was established to describe for this relationship.
Heat transfer coefficients were measured for a large number of samples. Compared with an empty channel, introducing a porous copper sample enhanced the heat transfer coefficient by a factor of 2–10. The samples with low porosities and large pore sizes showed high heat transfer coefficients. There was an optimal porosity range for good heat transfer performance at a given pore size. The heat transfer coefficient of LCS porous copper with double-layers was sensitive to the placement-order of the layer. A segment model was developed to predict the heat transfer coefficient of multilayer structures and the predictions agreed well with the experimental results.
The mechanical properties of LCS porous copper fabricated with fine copper particles were studied by compression, bending and tensile tests. The mechanical strength and apparent modulus, decreased with porosity. The porous copper samples with large pore sizes had better mechanical performance. The extended Mori-Tanaka model was used to predict the modulus and the predictions agreed well with the experimental data.