THE EFFECT OF POWDER PROCESSING ON THE COEFFICIENT OF THERMAL-EXPANSION OF MOSI2-SI3N4 COMPOSITES

The coefficient of thermal expansion (CTE) of MoSi2-Si3N4 (10, 20, 40 vol.%) composites decreases as the volume fraction of Si3N4 increases. Analysis of the microstructural variables suggests that the CTE of th e composites is independent of MoSi2-grain size but a function of Si3N 4 particle size, increasing with decreasing particle size. At the high volume percent (approximate to 40%) of Si3N4 particulates required in MoSi2 so that the CTE of the composite is close to that of Mo, Kerner 's model provides the closest prediction to the experimental data. Dev iation from the prediction is most likely a result of microcracks at M oSi2/Si3N4 interfaces. (C) 1997 Elsevier Science S.A.