scholarly journals Strongly Orthotropic Open Cell Porous Metal Structures for Heat Transfer Applications

Metals ◽  
2018 ◽  
Vol 8 (7) ◽  
pp. 554 ◽  
Author(s):  
Marcel Fink ◽  
Olaf Andersen ◽  
Torsten Seidel ◽  
André Schlott
Keyword(s):  
Sheet Metal ◽  
Porous Metal ◽  
Storage Device ◽  
Porous Metals ◽  
Metal Fiber ◽  
Latent Heat Storage ◽  
Open Cell ◽  
Metal Structures ◽  
Anisotropic Structures ◽  
The Difference

For modern thermal applications, open cell porous metals provide interesting opportunities to increase performance. Several types of cellular metals show an anisotropic morphology. Thus, using different orientations of the structure can boost or destroy the performance in thermal applications. Examples of such cellular anisotropic structures are lotus-type structures, expanded sheet metal, and metal fiber structures. Lotus-type structures are made by casting and show unidirectional pores, whereas expanded sheet metal structures and metal fiber structures are made from loose semi-finished products that are joined by sintering and form a fully open porous structure. Depending on the type of structure and the manufacturing process, the value of the direction-dependent heat conductivity may differ by a factor of 2 to 25. The influence of the measurement direction is less pronounced for the pressure drop; here, the difference varies between a factor of 1.5 to 2.8, depending on the type of material and the flow velocity. Literature data as well as own measurement methods and results of these properties are presented and the reasons for this strongly anisotropic behavior are discussed. Examples of advantageous applications, for example a latent heat storage device and a heat exchanger, where the preferential orientations are exploited in order to gain the full capacity of the structure’s performance, are introduced.

Progress on Investigation of Pores During Selective Laser Melting of Metal Powders and Future Work Discussion

2011 ◽  
Vol 291-294 ◽  
pp. 3088-3094
Author(s):  
Jin Hui Liu ◽  
Wen Juan Xie ◽  
Qing Song Wei ◽  
Li Wang
Keyword(s):  
Selective Laser Melting ◽  
Physical And Mechanical Properties ◽  
Porous Metal ◽  
Complex Structures ◽  
Metal Powders ◽  
Porous Metals ◽  
Laser Melting ◽  
Metal Structures ◽  
Metal Parts ◽  
Future Work

Pores are always considered as a kind of defect during manufacturing metal parts via many conventional processes. But porous metals have outstanding physical and mechanical properties which providing them double natures of function and structure, and are applied in many fields of science and technology. Selective laser melting (SLM), developed within current years, has the advantages of producing metal parts with complex structures, and can be used to manufacture complex structures of any kind theoretically. A new method of making porous complicated metal structures via SLM is put forward. Then, the meaning of this method, research advance and future work discussion are presented in this paper, which lays a method foundation for future study and build a new field for both porous metal parts and SLM technology.

Characterization of three- and four-point bending properties of porous metal fiber sintered sheet

2014 ◽  
Vol 56 ◽  
pp. 522-527 ◽  
Author(s):  
Wei Zhou ◽  
Qinghui Wang ◽  
Weisong Ling ◽  
Liangzong He ◽  
Yong Tang ◽  
...  
Keyword(s):  
Porous Metal ◽  
Metal Fiber ◽  
Bending Properties ◽  
Four Point Bending

Hard Materials with Tunable Porosity

MRS Bulletin ◽  
2009 ◽  
Vol 34 (8) ◽  
pp. 561-568 ◽  
Author(s):  
Jonah Erlebacher ◽  
Ram Seshadri
Keyword(s):  
Porous Materials ◽  
Self Assembly ◽  
Porous Metal ◽  
Ceramic Materials ◽  
Equilibrium Temperature ◽  
Length Scale ◽  
Porous Metals ◽  
Hard Materials ◽  
Mesoporous Zeolites ◽  
Pattern Forming

AbstractPorous metals and ceramic materials are of critical importance in catalysis, sensing, and adsorption technologies and exhibit unusual mechanical, magnetic, electrical, and optical properties compared to nonporous bulk materials. Materials with nanoscale porosity often are formed through molecular self-assembly processes that lock in a particular length scale; consider, for instance, the assembly of crystalline mesoporous zeolites with a pore size of 2–50 nm or the evolution of structural domains in block copolymers. Of recent interest has been the identification of general kinetic pattern-forming principles that underlie the formation of mesoporous materials without a locked- in length scale. When materials are kinetically locked out of thermodynamic equilibrium, temperature or chemistry can be used as a “knob” to tune their microstructure and properties. In this issue of the MRS Bulletin, we explore new porous metal and ceramic materials, which we collectively refer to as “hard” materials, formed by pattern-forming instabilities, either in the bulk or at interfaces, and discuss how such nonequilibrium processing can be used to tune porosity and properties. The focus on hard materials here involves thermal, chemical, and electrochemical processing usually not compatible with soft (for example, polymeric) porous materials and generally adds to the rich variety of routes to fabricate porous materials.

Autonomes Oberflächenschleifen von Aluminium-Anbauteilen/Autonomous grinding of lightweight constructions

2020 ◽  
Vol 110 (07-08) ◽  
pp. 507-510
Author(s):  
Jan-Oliver Brassel ◽  
Severin Hönle ◽  
Jürgen Fleischer ◽  
Hannah Pulli
Keyword(s):  
Sheet Metal ◽  
Metal Surfaces ◽  
Surface Finishing ◽  
Technological Solution ◽  
Metal Structures ◽  
Car Body

Zum Erfüllen der hohen Anforderungen an fehlerfreie Blechteiloberflächen werden häufig manuelle Aufwendungen in die Fertigstellung der Bauteile investiert. Mit Blick auf Produktivität und Wiederholgenauigkeit sollen Teilumfänge der Fertigstellung automatisiert werden. Inhalt dieses Beitrags ist die Konzeption einer Prozesskette zum autonomen Schleifen von Karosseriebauoberflächen sowie die Betrachtung eines Algorithmus zur Berechnung der Bearbeitungsreihenfolge.   Flawless paintwork on car body structures does require defect-free sheet metal surfaces. Therefore, mainly inline and manual refinement efforts are made to surface finishing the single car bodies before painting. Targeting productivity and repeat accuracy can make it necessary to automate certain amounts of this labour-intensive process. This paper presents a technological solution for autonomously grinding sheet metal structures as well as detailing an algorithm for calculating the sequence of steps for autonomous grinding.

scholarly journals Preparation and Characterization of Gradient Compressed Porous Metal for High-Efficiency and Thin-Thickness Acoustic Absorber

Materials ◽  
2019 ◽  
Vol 12 (9) ◽  
pp. 1413 ◽  
Author(s):  
Xiaocui Yang ◽  
Xinmin Shen ◽  
Panfeng Bai ◽  
Xiaohui He ◽  
Xiaonan Zhang ◽  
...  
Keyword(s):  
Sound Absorption ◽  
High Efficiency ◽  
Structural Parameters ◽  
Porous Metal ◽  
Theoretical Models ◽  
Absorption Efficiency ◽  
Total Thickness ◽  
Porous Metals ◽  
Absorption Coefficients ◽  
Optimal Average

Increasing absorption efficiency and decreasing total thickness of the acoustic absorber is favorable to promote its practical application. Four compressed porous metals with compression ratios of 0%, 30%, 60%, and 90% were prepared to assemble the four-layer gradient compressed porous metals, which aimed to develop the acoustic absorber with high-efficiency and thin thickness. Through deriving structural parameters of thickness, porosity, and static flow resistivity for the compressed porous metals, theoretical models of sound absorption coefficients of the gradient compressed porous metals were constructed through transfer matrix method according to the Johnson–Champoux–Allard model. Sound absorption coefficients of four-layer gradient compressed porous metals with the different permutations were theoretically analyzed and experimentally measured, and the optimal average sound absorption coefficient of 60.33% in 100–6000 Hz was obtained with the total thickness of 11 mm. Sound absorption coefficients of the optimal gradient compressed porous metal were further compared with those of the simple superposed compressed porous metal, which proved that the former could obtain higher absorption efficiency with thinner thickness and fewer materials. These phenomena were explored by morphology characterizations. The developed high-efficiency and thin-thickness acoustic absorber of gradient compressed porous metal can be applied in acoustic environmental detection and industrial noise reduction.

Thermal Conductivity Enhancement in a Latent Heat Storage Device

2013 ◽  
Vol 860-863 ◽  
pp. 590-593
Author(s):  
Cha Xiu Guo ◽  
Ding Bao Wang ◽  
Gao Lin Hu
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Solid State ◽  
Liquid Phase ◽  
Phase Change ◽  
Latent Heat ◽  
Heat Storage ◽  
Storage Device ◽  
Latent Heat Storage ◽  
Conductivity Enhancement

High conductivity porosity materials are proposed to enhance the phase change materials (PCM) in order to solve the problem of low conductivity of PCM in the latent heat storage device (LHSD), and two-dimensional numerical simulation is conducted to predict the performance of the PCM by CFD software. During the phase change process, the PCM is heated from the solid state to the liquid phase in the process of melting and from the liquid phase to the solid state in the solidification process. The results show that porosity materials can improve heat transfer rate effectively, but the effect of heat transfer of Al foam is superior to that of graphite foam although the heat storage capacity is almost the same for both. The heat transfer is enhanced and the solidification time of PCM is decreased since the effective thermal conductivity of composite PCM is increased.

Heat Transfer and Fluid Flow in Sintered Metallic Fiber Structures

2010 ◽  
Vol 638-642 ◽  
pp. 1884-1889 ◽  
Author(s):  
Olaf Andersen ◽  
Jens Meinert
Keyword(s):  
Heat Transfer ◽  
Fluid Flow ◽  
Heat Storage ◽  
Short Fiber ◽  
Analytical Models ◽  
Flow Properties ◽  
Metal Fiber ◽  
Open Cell ◽  
Sintered Metal ◽  
Inner Surface

Sintered metal fiber structures show a favourable ratio between pressure drop and inner surface area. Their exclusively open-cell morphology makes them well suited for heat transfer or temporary heat storage applications. Recently, highly conductive sintered metal fiber structures were successfully prepared from melt extracted aluminum alloy fibers. The heat conduction and fluid flow properties of metallic sintered short fiber structures were determined experimentally and compared with simple analytical models. It was found that equations taken from the available literature yield good approximations to the experimental results.

Flame localization by porous metal-fiber fire arresters

1979 ◽  
Vol 18 (6) ◽  
pp. 420-421
Author(s):  
I. I. Strizhevskii ◽  
D. M. Karpinos ◽  
A. E. Rutkovskii ◽  
A. I. �l'natanov ◽  
V. A. Zorin ◽  
...  
Keyword(s):  
Porous Metal ◽  
Metal Fiber
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