Characterization of the mechanochemically processed silicon nitride-based powders

Nanostructured silicon nitride and aluminium nitride powder mixtures have been successfully produced by high-energy mechanical activation in the planetary mill. The effect of planetary milling parameters (time, ball-to-powder ratio, surfactants addition) and means of deagglomeration by the ultrasound disintegration (type of dispersant, the ultrasonic action) were studied. The resultant powders were examined by XRD, SEM and TEM as well as the specific surface area (BET) was measured and grain size distribution was analyzed. It has been found that significant agglomeration occurred in the samples milled with the highest energy accompanied by the severe destruction of the crystal lattice. The results show the crucial effect of dispersant action for a one-modal distribution of the milled powders.