High porosity micro- and macro-cellular copper foams with semi-open cell microstructure toward its physical and mechanical properties

Abstract

Herein, a powder compacting method was developed to fabricate high porosity micro-and macrocellular copper foams using CaCO 3 space holder. The cold compacted precursors were heated at different temperatures under the nitrogen atmosphere. The effects of precursor compaction pressure, space holder content and sintering temperature on cell microstructure, relative density, compressive and physical properties were investigated. The scanning electron microscopy (SEM) images showed a uniform distribution of interconnected pores with sizes of pores and channels less than 50 microns formed the semi-open cell structure of the fabricated foams. The evaluation of the foaming agent content, 0 to 20 (wt%), in precursor materials showed relatively large changes in the porosity percentage (27%-50%), with the utilitarian strength (43 MPa) and densification strain (40%) of the copper foams. For specimens having 20 wt% CaCO 3 , tuning the sintering temperature (600°C) and compacting pressure (500 MPa) of precursors tailored superior porosity percent (47%), remarkable compressive stress (501 MPa) and high thermal (43.8 W m −1 .k), and electrical conductivity (0.06×10 8 Ω −1 m −1 ) owing to a desirable foaming process. A massive gas release during the CaCO 3 decomposition and the strengthened cell walls of the copper foams during the sintering resulted in the high porosity and strength of the fabricated foams. The presented fabrication method and our results are the core elements for the development of new high porosity metal foams that can help the development of the future application of copper foams for a long-life anode for lithium-ion batteries, catalysis, and thermal and electrical performances as electronic cooling materials.

Review: Closed-Cell Metallic Foams Produced via Powder Metallurgy

“…For example, novel blowing agents such as boric acid were recently used during the 'sintering' (not melting) of aluminum and aluminum-alumina composites, resulting in porosity levels of 46-53%, when 50 wt.% boric acid was added [34]. Similar work also considered sintering using the same blowing agent with aluminum-fly ash particulate-aluminum composites [52], or aluminum-cubic boron nitride [53], while CaCO 3 was used as a blowing agent for copper foams [35]. It should be noted that the gas release onset temperature of boric acid is considerably lower than those of blowing agents used in the PCMFP, where metal melting rather than solid-state sintering is the goal.…”

“…For example, the PM route/powder foaming process [26,27], powder metallurgy process [28], powder compact process [29], powder compact route [30], powder compact melting technique [25], powder metallurgy foaming [31], the Fraunhofer process [32], and the powder compact melting process (PCMP) [17]. We, however, propose the name Powder Compact Melt Foaming Process (PCMFP), as this name more effectively captures the physics governing this process, whereas other names could also be applied to other processes or foams, e.g., for open-cell foams (the 'powder metallurgy route' was used to describe the processing of open-cell Mg foam [33]), or foaming using a blowing agent during solid state sintering [34,35] (not melting). Hence, from this point onwards, we will refer to the process as PCMFP.…”

Evaluating the Influence of Adding Natural Materials to Copper and Zinc Compounds

“…in these materials showed relatively large changes in the porosity percentage(27%-50%), with the utilitarian strength(43 MPa)and densification strain(40%)of the copper foams. For specimens having 20 wt% CaCO3, tuning the sintering temperature(600°C)and compacting pressure(500 MPa)of precursors tailored superior porosity percent(47%), remarkable compressive stress(501 MPa)and high thermal(43.8 W m−1.k), and electrical conductivity(0.06 × 10 8 Ω −1 m −1 ) owing to a desirable foaming process [2]. [3] in 2021 Porous forms of Cu, Al and Cu/Al were prepared by powder metallurgy and the effect of process parameters on the micro-hardness, porosity and the cooling rate was tested.…”