SIC-SI3N4 BONDED MATERIALS BY THE NITRIDATION OF SIC AND TALC

Silicon carbide-based materials are used in many applications due to t heir good thermo-mechanical properties at high temperatures. The nitro genous bond formed from nitriding reactions of silicate minerals seems to be an interesting method to obtain these materials. In this work, the reaction of SIC with talc and N-2 atmosphere is studied. Pellets a nd/or bars of SiC-talc mixtures were reacted within the range 1395-165 0 degrees C. Reaction products were studied through XRD, textural prop erties, bending strength and microscopy. Reactions and mechanisms for this system are proposed. Silicon nitride is formed as principal bond phase. During reaction, volatilization of Mg takes place, where its lo ss is favoured at high temperatures and high N-2 flow rates. A loss of SiO(g) is also observed. Mechanical strength has a linear relation wi th the bond phase content. (C) 1998 Elsevier Science Limited and Techn a S.r.l. All rights reserved.