Quantitative Microstructural Analysis of Sintered Silicon Nitride by Using a Thin-Window Energy Dispersive X-Ray Detector System
Special ceramics such as Si3N4 have found broad application as structural components in high-temperature environments. Due to its strong covalent character Si3N4 may only be densified via a liquid phase sintering process after adding suitable metal oxides, e.g. Y2O3 and Al2O3 as sintering aids. By means of hot-pressing, pressureless sintering or hot-isostatic pressing a dense, polyphase material with excellent mechanical properties has been achieved, if the primary powder properties, the nature and amount of sintering aids and the processing parameters are carefully controlled. Dense Si3N4 is characterized by an amorphous grain boundary phase at intergranular contacts and triple grain junctions. In the case of (Y2O3+Al2O3)-fluxed material this glassy phase has been identified by high spatial resolution techniques1 as a Y-Al-Si-O-N oxinitride which shows a typical pattern of impurity elements depending on the sintering powder and the processing technique employed2,3.
KeywordsIsothermal Section Spot Measurement Pressureless Sinter Sinter Silicon Nitride Liquid Phase Sinter Process
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