Abstract
A fabrication technology of closed-cell copper foams (CCCFs) based on powder metallurgy is proposed, by using the expanded polystyrene foams (EPS) spheres with the prescribed diameter as the space holder before sintering. The material characterization and the quasi-static compressive behaviors of both uniform and graded CCCFs at different temperatures were experimentally studied. A high temperature weakens the initial compressive modulus, plateau stress, and effective energy absorption for both uniform and graded CCCFs; meanwhile, the onset strain of densification and the maximum energy absorption efficiency are less sensitive to temperature, especially for the graded CCCFs. Compared with the uniform CCCF, the graded CCCF with even a small relative density exhibits superiority in terms of the effective energy absorption and the maximum energy absorption efficiency, attributed to the much larger onset strain of densification for the gradient pore arrangement. Finite element simulations based on the ideal sphere foam model can basically mimic the compressive performance of the CCCF samples. It is also found that both the decrease of pore diameter and the increase of cell wall thickness could improve the compressive performance of the CCCFs.
Highlights
Porous metals or metal foams exhibit great performance in energy absorption, electrical conductivity, and thermal conductivity [1,2,3,4,5], and are widely applied as crashworthiness components, battery electrodes, and heat exchangers [6,7,8,9,10,11]
Tahdee cfroommpthletepogweodmeredtriyd onfothceolslpaphseereinptohreesprisocpersessoerfvEePdSidnetchoemfpooamsitisoanm. pTlhees caofmterpltehtee sgienotmereintrgy, wofitthhelesspshmereesopodrefseicstsprwehseicrhveadreincothmemfooanmlysfaomupnldesinafttheer tahleumsinintuermingcl,owseitdh-cleelslsfmoaemsos [d2e2f,e2c6t,s40w].hich are commonly found in the aluminum closed-cell foams [22,26,40]
The closed-cell copper foams (CCCFs) with prescribed sphere pores can be fabricated by powder metallurgy with the expanded polystyrene foams (EPS) spheres as the space holder
Summary
Porous metals or metal foams exhibit great performance in energy absorption, electrical conductivity, and thermal conductivity [1,2,3,4,5], and are widely applied as crashworthiness components, battery electrodes, and heat exchangers [6,7,8,9,10,11]. Electro-deposition [18] is applied to produce open-cell metal foams, in which the metal is deposited onto the surface of the organic support by an electrochemical method, and the support is subsequently removed by degreasing. The production of metal foam by casting is easy to realize industrial production and the cost is low, but it has some shortcomings, e.g., uncontrollable cell size, cell shape irregularity, non-uniform distribution of the cells, inhomogeneous composition of the matrix material, and introduction of impurities [21]. PM can be used to produce closed-cell and open-cell metal foams with a controllable cell shape and cell size, uniform distribution of the cells, and the necessary composition and properties of the metal matrix [23]. Additive manufacturing is employed, but only to fabricate open-cell foams by binder jetting [15] or a 3D-printed polymer mold [16,17], followed by pressureless sintering
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