Particle size and fraction required to stabilise aluminium alloy foams created by gas injection

Abstract

Liquid metal foam owes its stability to the presence of solid non-metallic particles. To elucidate the conditions under which such particles stabilise foams, 15 different aluminium-alloy based metal matrix composites were manufactured and melted, after which air was injected with the objective to create bubbles and eventually metal foam. Bubble and foam formation was monitored in-situ by Xray radioscopy. All systems were classified and labelled foamable, partially foamable and unfoamable. Foamable composites form a preferred range in the stability diagram displaying particle fractions vs. particle size, thus experimentally confirming earlier claims. All investigated composites fall into the same range even though their alloy compositions and particle types vary.

Effect of Primary Crystals on Pore Morphology during Semi-Solid Foaming of A2024 Alloys

“…Also, the primary crystals acting as a thickener in the melt are larger in size than those of the oxides. Moreover, the primary crystals are generally larger than the preferred range of thickener sizes in the melt route [10]. Therefore, foams fabricated in a semi-solid state may have different stabilization mechanisms than those in the melt route.…”

Three‐dimensional (3D) flexible nanofibrous network knitting on hierarchical porous architecture

“…Until now, hierarchical porous architectures have been successfully synthesized by employing the following technological routes: (a) Preparation of hierarchical porous composites by coating of mesoporous or microporous frameworks onto much open porous substrates; (b) Template‐directed method which uses the inherent pore structure of sacrificial templates to generate hierarchical porous frameworks after imprinting processes . Particle‐stabilized foams are particularly attractive and simple templating processes which have been largely reported in recent years . Despite their striking advantages, hierarchical structuring of porous materials using this method still remains a challenging scientific task since the pore‐size distributions of as‐prepared ceramics are usually homogeneous …”

Stabilization Mechanism of Semi-Solid Film Simulating the Cell Wall during Fabrication of Aluminum Foam

“…Furthermore, size of primary crystals is quite large and out of the stabilization region in the parameter map proposed by Jin et al [10]. Likewise, primary crystals were classified as partially foamable or unfoamable by Heim et al [11]. Despite, our group found it possible to fabricate stabilized foams in the Semi-solid route out of the stabilization region in the map.…”

“…Moreover, Heim et al fabricated foams with various types of thickener including primary crystal and classified them as foamable, partially foamable, or unfoamable. They also expressed that the parameter map proposed by Jin et al could be adapted to various types of thickener [11].…”