Decrease of silicon defects in oxynitride glass

• Published in: Journal of non-crystalline solids Vol. 209; no. 1; pp. 69 - 75
• Main Authors: Oota, Masaaki, Kanamori, Takeshi, Kitamura, Satoshi, Fujii, Hiroyuki, Kawasaki, Takashi, Sekine, Keiji, Manabe, Chiaki
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 1997
• Subjects: T170; P345; N180
• ISSN: 0022-3093; 1873-4812
• DOI: 10.1016/S0022-3093(96)00546-7

Mg–Si–Al–O–N oxynitride glass fiber with an average elastic modulus of 115 GPa and tensile strength of 4500 MPa was prepared by melting the mixtures of SiO 2, MgO, Al 2O 3 and Si 3N 4 powders at 1720°C and refined at 1600°C in molybdenum crucible in flowing nitrogen gas. The high tensile strength was achieved by decreasing silicon particles which were internal defects of the oxynitride glass. The glass of 3 mm thick had transmittance of more than 90%. The silicon particles were generated in the glass by decomposition of SiO 2 above 1720°C under strong reducing conditions, which caused coloration of the glass and low fiber strength. Refining of the glass at 1600°C decreased the silicon particles. The reaction between Si–N, Si–O– in the glass matrix and molybdenum formed molybdenum silicides with the evolution of nitrogen and oxygen gases. Silicon particles were oxidized by oxygen evolved.