MICROSTRUCTURE AND PROPERTIES OF NANOSEMICRYSTALLINE SI3N4 CERAMICS WITH DOPED SINTERING ADDITIVES - PART I - MICROSTRUCTURAL CHARACTERIZATION OF NANOSEMICRYSTALLINE SI3N4 POWDERS

The characteristics of nanosized silicon nitride powders with doped Y2 O3 and Al2O3 fabricated by a plasma-reacted chemical process were inve stigated. The chemical compositions of the powders were analyzed by we t chemical analysis. The morphology and the size distribution were det ermined by transmission electron microscopy (TEM). TEM with energy dis persive spectroscopy (EDS) was used to verify the existence of sinteri ng additives in each individual particle. The crystal structure of the powders was identified by the selected area diffraction pattern (SADP ). X-ray diffraction (XRD) technique was used for phase analysis and t he measurement of degree of crystallinity. The characteristics of chem ical bonding was analyzed by using Fourier transform infrared spectros copy (FTIR).