Experimental Determination of Relative Density and Percentage Porosity of Open Cell Aluminium foam Produced from Sand Salt Mould Method Raja Yateesh Yadav Part time Research Scholar, Department of Mechanical Engineering, UBDTCE, Davangere, INDIA Dr. E. S. Prakash Professor Department of Mechanical Engineering, UBDTCE, Davangere, INDIA Abstract— Metallic foams have received broad attention due to their potential applications in many different fields, such as sound insulation, heat exchangers, filters, and catalyst carriers. In the last two decades metallic foams, which are porous metals with high porosity and relatively large cells, have been developed and are growing in use as new functional materials because of the unique combination of properties which can be derived from their cellular structure. Aluminium foam is a light weight porous material which appears to be promising metallic foam especially for aerospace applications. Aluminium foam can be produced by different methods like direct foaming with foaming agents in a metal powder mixture, direct foaming with foaming agents in a melt, by using different casting techniques etc., But each process will have its own advantages and shortcomings. There is a need for producing aluminium foam from easily available materials with low cost. In the present work, an attempt has been made to develop open cell aluminium foam from sand salt mould method using NaCl crystal as space holder whose relative density and percentage porosity were determined experimentally. Keywords— Aluminium foam; sand salt mould method; NaCl crystal; relative density; percentage porosity; I. INTRODUCTION In the recent decades, open cell metal foams have been widely used because of their diverse properties in various areas including aerospace, electronics and automotive engineering applications [1,2,3]. They are a relative new class of materials with very promising applications in which it’s low density and other thermal, mechanical, electrical and acoustical properties make this material an excellent means of performance improvement. Among their current applications, open cell metal foams are found useful for the construction of light weight structures, energy absorption devices, currently being used by some vehicle manufacturers, and for various fluid flow and thermal applications which is our interest in this work. Foams are the result of a two phase combination created by various processes most of which include the dispersion of a gas through a liquid without dissolving the gas completely. This is very similar to the emulsion process (combination of two immiscible liquids) but having the difference that a gas phase must exist in the foam. Nine distinct processes have been developed to make metal foams of which four are now used in the commercial fabrication of these materials [1]. 1. Bubbling gas through a molten alloy (Al-Al2O3, Al-SiC) 2. By stirring a foaming agent (typically TiH2) into a molten alloy (typically an aluminum alloy) 3. Consolidation of a metal powder, generally aluminum alloys, with a particulate foaming agent (TiH2) followed by heating into the mushy state when the foaming agent releases hydrogen expanding the material (Al, Zn, Fe, Pb, Au). 4. Manufacturing of ceramic moulds from a wax or polymer foam precursor, following the burning out of the precursor and pressure infiltration with molten metal powder slurry which is then sintered (Al, Mg, Ni-Cr, stainless steel and Cu). The differences between open cell and closed cell metal foams are mainly how the geometry of the cell is formed (See Figs.1 and 2). In the open cell group the cells are not closed from each other and the flow of other materials through one cell occurs freely to another adjacent cell. In the closed cell arrangement, the cell walls which completely close the cells from one another with the formation of individual cell compartments. Fig 1. Open cell metal foam sample [5] Fig 2. Closed cell metal foam sample Vol. 5 Issue 04, April-2016 International Journal of Engineering Research & Technology (IJERT) ISSN: 2278-0181 http://www.ijert.org IJERTV5IS040305 (This work is licensed under a Creative Commons Attribution 4.0 International License.) Published by : 152