Aluminium foam is a special class of porous material with cellular structure defined by randomly distributed air pores in metallic matrix. It possesses high stiffness and low density. Additionally, the net-shaping of the aluminium foam has given a new dimension to the manufacturing technique. It results in a near net-shape semi-finished product for the light weight structures in the automotive and aerospace industries. The present paper is focussed on the laser assisted aluminium foaming from a foamable precursor material and its possible applications in net shaping of 3D structures. A strong variation in the cell size or structure is detected depending upon the processing parameters and their shape varies from circular to irregular ellipsoidal or deformed circular structure. At higher processing speed, the width of foamed structure becomes larger (5.03 mm) and the average cell size is relatively fine (0.2 mm), but still the base has not fully expanded. On the other hand at lower processing speed the width of foamed structure is scaled up to 8.13 mm having a large size porosity and with a average cell size of about 3 mm. For further characterization, the density and volume of the each aluminium foam block was calculated. To estimate the cell wall yield strength, microhardness measurements were made on the cell edges that is at the cross-sectional area between the cells. The paper demonstrate the feasibilty of laser assisted aluminium alloy foaming and net-shaping. The results yield a localized and unidirectional expansion of the foam in the direction of laser irradiation. Porous 3D rectangular structures with a relative density of 0.33 were created and a pore size gradient does exist with the slow and fast processing speed.
Net-shaping via aluminum foaming
2001
5 Seiten, 3 Bilder, 6 Quellen
Conference paper
English
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