Production of carbon coated Al-foams and evaluation of their mechanical response
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Production of carbon coated Al‑foams and evaluation of their mechanical response F. Stergioudi1
© Springer Science+Business Media, LLC, part of Springer Nature 2020
Abstract The feasibility of a cost-efficient method to produce carbon coated Al-foams in a single-step heating process is investigated. In this context, a dissolution-sintering process for manufacturing metal foams is developed using raw cane sugar as both the space holder material and the carbon generating medium. The structural characteristics of the produced carbon coated Al-foams were evaluated by XRD, Raman and SEM analyses. Static compression tests were conducted to determine the mechanical response of the produced carbon coated Al-foams. The produced carbon coated Al-foams were fully covered with an external carbon layer having a relatively uniform thickness, despite the inherent complex 3D surface of the foam. The carbon deposition process led to a significant increase of the compression strength of the Al-foam. A strain softening behavior was observed for the carbon coated Al-foams attributed to micro-cracking of aluminum carbides. The produced carbon coated Al-foams can potentially be used as a catalyst support structure. Keywords Al-foam · Carbon coating · Microstructure · Mechanical response
1 Introduction Al-foams present unique properties such as high strength-to weigth ratio. Along with their complex inherent 3D structure they attract a lot of scientific and technological interest for a number of potential applications. Open-cell metal foams emerge opportunities for application in the field of lightweight structures, heat exchange, catalytic filter applications and applications in batteries and supercapacitors as porous electrodes [1–7]. In the last decade, cellular metallic materials have attracted increasing interest as carriers for catalysts due to higher heat transfer rates compared to ceramic ones [3–6]. Open-cell metal foams are commonly produced by using space holder materials. Depending with the space holder particle size distribution a wide range of open cell metal foams can be produced. Space holders can be removed using diverse ways, e.g. by shaking, leaching or by pyrolysis. Several space holder materials have been reported such as NaCl * F. Stergioudi [email protected] 1
Physical Metallurgy Laboratory, School of Mechanical Engineering, Aristotle University of Thessaloniki, Thessaloniki, GR 54124, Greece
particle, carbamide (urea) or carbonate particles. The ability to determine and tailor the geometric features of the cellular structure to any given process is a significant advantage of space holder technique [7–9]. In the context of catalytic support structures, metal foams combine several advantages such as, improved mechanical properties (in terms of impact strength and brittleness), tailored miscibility (including radial mixing) and lower pressure drop (compared to a fixed bed of powder) than ceramic ones. These properties make them attractive candidates for catalytic applications. For the case of Al-foams the hi
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