Processing of silicon carbide-boron carbide-aluminium composites

The aim of this work was to shed light on the wetting mechanism in the SiC-B(4)C-Al system and to explore processing routes that enable infiltration of Al alloys into these ceramic powder mixtures without the formation of the deleterious reaction product Al(4)C(3). For this purpose, powder mixtures consisting of SiC and pre-treated B(4)C were pressureless infiltrated with At alloys at relatively low temperatures under an inert gas atmosphere. Depending on the characteristics of the starting powders fully infiltrated composites were achieved in the temperature range of 935-1420 degrees C. It was observed that addition of pre-treated B(4)C to SiC enabled complete infiltration of the similar to 0.6 cm thick preforms. The bulk density of all produced composites was > 98% of the X-ray density. By controlling the surface chemistry and particle size of the starting powders as well as the processing conditions, the wetting behaviour and reaction kinetics of this system could be tailored so as to render fully dense SiC-B(4)C-Al composites devoid of Al(4)C(3). (c) 2008 Elsevier Ltd. All rights reserved.