자전연소합성법으로 제조된 SiO2첨가된 MoSi2분말 내에서의 SiO2의 거동 연구

Abstract

In order to investigate the behavior of SiO 2 in the molybdenum silicide powders, crystal structure of these powders was measured by XRD, in addition, surface composition and surface phase (or chemical states) and microstructure were analysed by XPS and TEM, respectively. Mo-silicide powders containing SiO 2 were synthesized by SHS (Self-Propagating High-Temperature Synthesis) technique. In XRD result, according to increase of SiO 2 contents, the crystal structure for synthesized MoSi 2 powders was still typical MoSi 2 bct without any other phases. By XPS analysis, the surface of Mo and Si source powders was covered with MoO 3 and SiO 2 , respectively, and the surface of synthesized MoSi 2 powder was also covered with MoO 3 and SiO 2 , which were stable oxides at room temperature. However, according to increase of SiO 2 addition, MoSi 2 phase in XPS spectra decreased and SiO 2 phase increased relatively in synthesized MoSi 2 powders. From the results by XPS and XRD, we found that the existent SiO 2 has amorphous structure. In the microstructure, the small particulates of the synthesized products added SiO 2 agglomerated together to form larger clusters (from ~10 nm to ~1 μm). From TEM, XPS, and XRD results, we found that the out layer of agglomeration of synthesized MoSi 2 powder is surrounded by amorphous SiO 2 .