Effects of foaming agent and boron carbide additions on the foamability behaviour of al based metallic foam produced by powder metallurg

Abstract

Al foams have found increasing applications in industry due to their exceptional mechanical, thermal, acoustic, electrical and chemical properties. Several techniques and number of production parameters are used to produce engineering Al foams. In this paper, effect of foaming agent and boron carbide additions on the foamabilty behaviour of Al based metallic foam, produced by powder metallurgy, was investigated. Al powders and various amounts of (1, 1.5 and 2 wt%) titanium hydrate (TiH2) and B4C (1, 3, 5 and 7%) were mixed for 30 minutes in a three dimensional turbula. Mixed powder were compacted at 300 MPa pressure to produce powder blanks and then preheated to 400°C in a furnace for 3 h. Samples were then deformed by 25%. For foaming, samples were heated to 690°C for about 15 minutes and cooled to room temperature. Effect of foaming agent and boron carbide amounts on the pore size, pore shape, density and the linear expansion coefficient of samples were investigated by using optical an electron microscopes. Experimental results have indicated that boron carbide more than 5% reduced the foamability even with 2% TiH2 addition.© 2008 Metal Powder Industries Federation.