RECYCLING OF CARBON CONTAINING ALUMINUM MATRIX COMPOSITES VIA THEIR REMELTING

Abstract

Nowadays aluminum alloys are strong enough to have good mechanical properties. What is their weak point is stiffness (Young modulus) that cannot be significantly improved be standard alloying elements. Carbon or carbon containing substances like silicon carbide with high values of Young modulus are often used in aluminum matrix composites with intention to increase stiffness of the resulting material. However, carbon bearing aluminum matrix composites are not easily recycled via melting because of reactivity of molten aluminum with carbon or carbides. Direct remelting of Al-SiC composite resulted in silicon containing melt and aluminum carbide while oxide envelop of input material keeps original shape to as high temperature as 850 °C. Addition of fluxes helps to break oxide layers but it does not prevent aluminum from reaction with carbon to form aluminum carbides.