Foamability of Particle Reinforced Aluminum Melt

Abstract

The foaming of aluminum melt of LKR‐Austria is investigated. The foaming was performed in a furnace chamber at adiabatic conditions to keep the foam in liquid state. The foams were taken out from the chamber after 1, 10 and 100 min isothermal holding time and cooled in air or quenched in water. The final cellular structure depends on the following parameters: particle (composition, shape and size, volume fraction), gas (composition and purity), the particle‐surface interactions, matrix alloy composition and temperature of foaming.Metallographical examinations are carried out after freezing the foamed melt by the help of Scanning Electron Microscopy. The cell wall thickness, the particle distribution and the existing phases are determined. Transmission Electron Microscopy and Auger Electron Spectroscopy are used to analyze the surface skin of the cells and to determine the oxide layer thickness depending on the different foaming gases.An equipment called High Temperature Maximum Bubble Pressure Tensiometer (HTMBPT) was built to measure the apparent surface tension of the particle‐stabilized melt. Semi quantitative description of the experimental phenomena are presented.

Effect of CaCO₃ Foaming Agent at Formation and Stabilization of Al-Based Foams Fabricated by Powder Compact Technique

“…8) Former phenomenon is currently associated with an additional stabilisation effect of oxide skin formed on surface of cell faces via the reaction of liquid Al with oxidizing CO 2 gas. 5,6,[8][9][10][11][12][13] Although the results related to in situ monitoring of foam formation from powder compacts being produced with TiH 2 foaming agent have been published, [14][15][16][17][18][19][20][21] formation of foams created from powder compacts with CaCO 3 as gas source has not yet been systematically assessed by in situ experiments. 22) The present paper is aimed at in situ analysis of foam formation and stability at heating Al-based powder compacts with CaCO 3 by comparison with those prepared with TiH 2 .…”

Manufacturing processes of cellular metals. Part I: Liquid route processes

“…Los parámetros que tienen mayor influencia en la estructura celular final son: las partículas cerámicas (composición, forma, tamaño), la cantidad de partí-culas [14 y 20] , el gas (composición y pureza), la composición de la aleación matriz [20] , la velocidad angular y el diseño del agitador, el flujo y presión del gas [18 y 40] , el tiempo de agitación y la viscosidad del fundido [41] , el agente espumante utilizado y la temperatura de espumado [20 y 30] . De otro lado, Eckert y Gerbeth demostraron que en un metal líquido de dos fases, los paráme-tros tales como el tamaño, distribución y velocidad de formación de las burbujas pueden ser controlados mediante la aplicación de campos electromagnéticos externos donde, finalmente, concluyen que los campos de tipo DC amortiguan las fluctuaciones turbulentas y reducen la dispersión de las burbujas de gas y los campos de tipo AC (p.e.…”

“…Aunque las aleaciones de aluminio son las de mayor uso [20] , también es posible espumar otros metales y sus aleaciones tales como el acero, níquel, cinc, cobre, plomo y magnesio [1 y 14] , donde la principal limitante es el punto de fusión del metal y el control de las burbujas una vez éste es espumado. En el caso del procesado de metales amorfos, tales como el Pd43Ni10Cu27P20, no se requiere el uso de partículas refractarias para la estabilización de la espuma debido a las altas viscosidades propias de estos metales y, para simplificar su procesamiento se utiliza el B 2 O 3 , hidratado como agente espumante [43][44][45] .…”

Effect of Silicon Carbide and Titanium Hydride on the Foamability of Aluminum Alloy (6061)

“…The gas is trapped inside and produces closed cells foam upon quenching the liquid metal. In another process, developed in Japan and known by Alporas process, a blowing agent, titanium hydride (TiH 2 ) is mixed with the aluminum melt to form a homogenous foam mixture [8]- [13]. The decomposition of the TiH 2 releases hydrogen gas that causes expanding of the aluminum melt and forming of the metal foam.…”