C. Uma Shankar, K. Jha, T. R. G. Kutty, K. N. Mahule, H. S. Kamath, Bhabha Atomic Research Centre, Mumbai, India; S. V. Kailas, Indian Institute of Science, Bangalore, India
Aluminum foams play a key role in providing cushion for absorption of shock and impact. They have been found increasing applications in a wide range of structural and functional products, due to their exceptional mechanical, thermal, acoustic, electrical and chemical properties and offer great potential for lightweight structures. Aluminium foam has potential application in transportation of radioactive materials. Aluminium foam structures have relative densities as low as 5 % of a solid structure and have high specific strength and stiffness per unit weight in comparison to other regularized packaging materials. This paper highlights the indigenously developed manufacturing process for aluminium foam to near net shape. The powder metallurgy technique has been used for manufacture of above-mentioned foams. In this process, a foaming agent is pre-compacted along with Al powder in cold isostatic press at 3000 bar and then extruded at 250oC. The extruded billet is heated to the foaming temperature, which leads to partial melting as well as the release of the hydrogen gas. The foam thus obtained has a density in the range of 0.2-0.3 g/cm3. The foam can be made into near net shape by choosing the proper mould. The foams are characterized in terms of their density, micro-macro structure, porosity content etc. The pore size was found to be in the range of 2-5 mm. The mechanical properties of the foam were evaluated by compression as well as impact testing. The yield strength (sy) of the aluminium foam, for a density of 0.3gm/cm3, was found to be 2 MPa. The Energy absorption characteristic of aluminium foam is compared with other contemporary packaging material like Indian teak wood. This paper, also discusses the effects of various processing parameters like compaction pressure, extrusion ratio, foaming temperature on the quality of the foam.
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