The role of TiN in the intergranular phase-forming process in TiN-dispersed Si3N

2019-09-11 21:23:27

phase grain films TiN intergranular

责任者: Schmid, Herbert K. 单位: Universitat Bonn, Inst. Anorg. Chemie, 53117 Bonn, Germany 来源出处: Journal of the American Ceramic Society,2005,88(2):404-410 摘要: Internal interfaces in two ceramic systems, monolithic Si3N 4 (SN) and TiN-dispersed Si3N4 nanocomposite (STN), were characterized by analytical transmission electron microscopy (TEM). in monolithic SN both MgO and Y2O3 dopants are preferentially hosted by the vitreous intergranular phase in pockets at triple grain junctions (TJ), whereas in STN composites the highest dopant concentrations were observed in grain and phase boundaries. The width of grain boundary films, as revealed by high-resolution TEM imaging, varied between approximately equals 0.8 nm in monolithic SN and approximately equals 1.0-1.2 nm in STN. Intergranular films with increased width approximately equals 1.8 nm were detected in SN-TiN phase boundaries. Although no enrichment of Ti could be detected in the intergranular phase, it appears that the presence of TiN dispersants indirectly contributes to the intergranular phase formation. It is assumed that TiO2 impurities sitting on TiN particle surfaces react with the matrix phase, resulting in a more oxidic nature of intergranular films due to increased SiO2 supply in intergranular regions. Phase-specific Si-L2,3 energy-loss near edge structure features, which could serve as fingerprints for phase identification, were observed in spatialdifference electron energy-loss spectra from grain boundary films and TJ pockets. 关键词: Titanium nitride;Ceramic materials;Nanostructured materials;Grain boundaries;Energy dissipation;Impurities;Transmission electron microscopy;Intergranular phase-forming process;Grain boundary films;Phase identification