Studies on Atmospheric Ageing of Nanosized Silicon Nitride Powders
نویسندگان
چکیده
Ageing of nanosized silicon nitride powder produced by the vapor phase reaction of silicon tetrachloride and ammonia has been studied in argon gas, in dry air and in air of 80% humidity, respectively, for 3 to 540 days. No remarkable changes were observed either in the bulk or the surface properties on storage in argon gas for 90 days. However, samples stored in dry air and humid air, respectively, exhibited remarkable oxidation and formation of N-H species. It was proved that nanosized silicon nitride powders should be stored and processed in oxygen-free conditions.
منابع مشابه
Simultaneous direct determination of aluminum, calcium and iron in silicon carbide and silicon nitride powders by slurry-sampling graphite furnace AAS.
A fast and accurate analytical method was established for the simultaneous direct determination of aluminum, calcium and iron in silicon carbide and silicon nitride powders by graphite furnace atomic absorption spectrometry using a slurry sampling technique and a Hitachi Model Z-9000 atomic absorption spectrometer. The slurry samples were prepared by the ultrasonication of silicon carbide or si...
متن کاملOxynitride Glasses Prepared from Gels and Melts
The structures of glasses prepared by melting mixtures of alkali borosilicate glass and silicon nitride powders and by ammonolysis of porous borosilicate gels were studied using Fourier transform infrared spectroscopy and combustion analysis. Whereas there was little evidence of nitride bond formation in the melt prepared glasses, Si-N and B-N bonding were observed in the gel-derlved glasses. I...
متن کاملEffect of gas composition on Si2N20 formation in the Si -C-N-O system
Formation of silicon oxynitride was observed during silicon nitride whisker synthesis from silica, carbon and nitrogen. The silicon oxynitride formation was limited to a bottom area of the charged powders and found both in whisker and powder. The possible reason for this localized Si2N20 formation is analysed, based on the effect of gas phase composition on the phase stability among 13-SiaN4, 1...
متن کاملThe effects of fuel chemistry and feedstock powder structure on the mechanical and tribological properties of HVOF thermal-sprayed WC–Co coatings with very fine structures
We have deposited a series of WC–Co coatings by the high velocity oxy fuel (HVOF) process, using three different powders, and different spray conditions. The powders are a nanocrystalline (Nanocarb), a near-nanostructured powder (Infralloy) containing a proprietary additive aimed at retarding grain growth, and multimodal (mixed micro and nano) powder (Nanomyte). HVOF spray conditions were stoic...
متن کاملMICROSTRUCTURAL STUDY OF SILICON NITRIDE WHISKERS PRODUCED BY NITRIDATION OF PLASMA-SPRAYED SILICON LAYERS
plasma-sprayed silicon layers have been used to produce silicon nitride layers with fibrous microstructure which optimizes fracture toughness and strength. SEM examination of the specimens shows that the surface is covered by fine needles and whiskers of Si3N4.In order to study the oxygen contamination effect as well as other contaminants introduced during spraying and nitridation processes, su...
متن کامل