Permeability of Aluminium Foams Produced by Replication Casting

Eugeny Furman,Maxim Cherny,Arcady Finkelstein

doi:10.3390/met3010049

Abstract

The replication casting process is used for manufacturing open-pore aluminum foams with advanced performances, such as stability and repeatability of foam structure with porosity over 60%. A simple foam structure model based on the interaction between sodium chloride solid particles poorly wetted by melted aluminum, which leads to the formation of air pockets (or “air collars”), is proposed for the permeability of porous material. The equation for the minimum pore radius of replicated aluminum foam is derived. According to the proposed model, the main assumption of the permeability model consists in a concentration of flow resistance in a circular aperture of radius rmin. The permeability of aluminum open-pore foams is measured using transformer oil as the fluid, changing the fractions of initial sodium chloride. Measured values of minimum pore size are close to theoretically predicted ones regardless of the particle shape. The expression for the permeability of replicated aluminum foam derived on the basis of the “bottleneck” model of porous media agrees well with the experimental data. The obtained data can be applied for commercial filter cells and pneumatic silencers.

Highlights

Open-pore metal sponges offer a wide range of possible applications, such as heat-exchangers, fuel cells, filtering processes, etc
Replicated aluminum foam was produced by the process described in Reference [3,5]
Measured values of average minimum pore size are close to theoretically predicted ones, regardless of the particle shape

Summary

Introduction

Open-pore metal sponges offer a wide range of possible applications, such as heat-exchangers, fuel cells, filtering processes, etc. Many state-of-the-art technologies are used for obtaining such permeable materials [1,2]. Replication casting can provide the advanced performances such as stability and repeatability of foam structure. The process can be described by the following steps. The porous bed of preheated NaCl particles is infiltrated with molten metal. The resulting composite after solidification can be shaped into the desirable form, and salt is subsequently removed by dissolution in water

Results

Discussion

Conclusion