JOINING OF SURFACE-MODIFIED CARBON-CARBON COMPOSITES USING A BARIUM-ALUMINUM-BOROSILICATE GLASS

Carbon/carbon composites (C/C) are known to be not wettable by most gl ass materials. in this paper, CIC have been joined by a barium-aluminu m-borosilicate glass (SABB) after modifying the composite surface with the formation of a silicon carbide layer. The surface modification ha s been obtained by heating, in an inert atmosphere, a silicon slurry d eposited on the composite surface at a temperature above the silicon m elting point, to achieve its transformation to beta-SiC A 'sandwich-li ke' joined structure (composite/glass/composite) has been mane by putt ing a slurry of SABB glass between two beta-SiC surface modified CIC s amples of approximately 10x12x2mm(3), then by heating them at a temper ature above the SABB softening point, in an inert atmosphere. The obta ined 'sandwich-like' joined structures were characterised by thermal a nalyses, X-ray diffraction, optical and scanning electron microscopy a nd compositional analysis. Mechanical characterisation was carried out using Vickers micro-indentation (at the glass/composite interface and in the glass joint) and with a shear stress test, performed on a comp ression test machine. The joined structures prepared with optimised co nditions have shear strength values of up to 30 MPa at room temperatur e. (C) 1998 Elsevier Science Limited. All rights reserved.