مطالعات فاز مرزدانهای و ریزساختاری سرامیکهای غیر اکسیدی نیترید سیلیسیم

Engineering ceramics are often difficult to prepare for observation because of their hardness, wear resistance and chemical inertness. Different silicon nitride containing Y2O3 and Al2O3 are prepared and etched using several different techniques and the most efficient methods are identified. The microstructure and grain-boundary composition were examined by electron microscopy (SEM, TEM), electron diffraction and energydispersive X-ray microanalysis. A method has been developed to quantify microstructure consisting of elongated, rod like -grains to discuss the interdependence between starting materials composition, processing condition, microstructure and resulting mechanical properties of dense Si3N4 materials. It is shown that post-sintering heat-treatment in air in the temperature between 1100-1450 C results in substantial crystallisation of the glassy phase.