Effect of nitrogen gas pressure during heat treatment on the morphology of silicon nitride fibers synthesized by carbothermal nitridation
| Autor: | Sotaro Baba, Tomoyo Goto, Sung Hun Cho, Tohru Sekino |
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| Jazyk: | angličtina |
| Rok vydání: | 2018 |
| Předmět: | |
| Zdroj: | Journal of Asian Ceramic Societies, Vol 6, Iss 4, Pp 401-408 (2018) |
| Druh dokumentu: | article |
| ISSN: | 2187-0764 21870764 |
| DOI: | 10.1080/21870764.2018.1542969 |
| Popis: | The effects of N2 gas pressure on the diameter and morphology of Si3N4 fibers obtained via carbothermal nitridation were investigated. Sol–gel-derived precursors containing a silica and carbon mixture were placed in an Al2O3 crucible and heat-treated under various N2 pressures from 0.1 to 0.5 MPa at 1500ºC. The heat-treated samples were characterized by X-ray diffraction (XRD), a scanning electron microscope (SEM) coupled with an energy dispersion X-ray (EDX) spectrometer, and transmission electron microscopy (TEM). Various nitride fibers with α- and β-phase Si3N4 were formed. The fiber diameter decreased with increases in N2 pressure, and nanometer-scale fibers of around 200 nm in diameter were obtained at a N2 pressure of 0.5 MPa. It was found that silicon oxynitride Si2N2O or its Al-doped form, O′-SiAlON, was produced due to high N2 pressure and doping with Al originating from the Al2O3 crucible. This oxynitride was considered to act as a template for Si3N4 fiber growth by the direct phase transformation mechanism. It was shown that the diameter of the Si3N4 fibers decreased for two reasons: decreased partial pressure of SiO gas due to high N2 pressure and increased formation of the silicon oxynitride templates. |
| Databáze: | Directory of Open Access Journals |
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