Separation of matrix alloy and reinforcement from aluminum metal matrix composites scrap by salt flux addition

Abstract

Separation of matrix alloy and reinforcements from pure Al-SiCp composite scrap by salt flux addition has been theoretically predicted using interface free energies. Experiments performed confirm the theoretical prediction. Complete separation of matrix aluminum and reinforcement from metal matrix composites (MMCs) scrap has been achieved by addition of 2.05 wt% of equimolar mixture of NaCl-KCl salt flux with a metal and particle yield of 84 and 50% respectively. By adding 5 wt% of NaF to equimolar mixture of NaCl-KCl, metal and particle yield improved to 91 and 73% respectively. Reusability of both the matrix aluminum and the SiC separated from Al-SiCp scraps has been analysed using XRD, SEM and DTA techniques. The matrix alloy separated from Al-SiCp scraps can be used possibly as a low Si content Al-Si alloy. However, the interfacial reaction that occurred during the fabrication of the composites had degraded the SiC particles.