Solid gas reactions of Y{sub 2}O{sub 3} + Si with N{sub 2} and oxidation of the products

Journal Article · Tue Aug 01 04:00:00 EDT 1995 · High Temperature and Materials Science

OSTI ID:218633

Yoenden, A; Kizilyalli, M ^[1]

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1. Middle East Technical Univ., Ankara (Turkey). Chemistry Dept.

During recent years, significant progress has been made in the development of engineering ceramic materials. Silicon nitride (Si{sub 3}N{sub 4}) is one of the most promising in this class. The densification of silicon nitride has been carried out with the addition of some high melting oxides, which are called densification aids. Improvements in high temperature strengths have been obtained either by increasing the viscosity of grain boundary phase, or by achieving a more refractory grain boundary phase. This was investigated by some workers with the addition of trivalent lanthanide oxides and yttrium oxides as sintering aids, which have high melting temperatures. The previously unreported solid-gas reactions of Y{sub 2}O{sub 3} + Si under nitrogen flow, with Fe or NaF promotors, were studied at different temperatures. The molar ratio of yttrium to silicon was changed from 2.5:1 to 1:2.5 and the reactions were carried out at 800--1,300 C. The identification of the products, Y{sub 2}Si{sub 2}O{sub 7}, Y{sub 2}SiO{sub 5}, Y{sub 2}Si{sub 3}N{sub 4}O{sub 3}, and Y{sub 4.67}(SiO{sub 4}){sub 3}O was done by X-ray powder diffraction and IR spectroscopy.

• OSTI ID: 218633
• Report Number(s): CONF-940468--
• Journal Information: High Temperature and Materials Science, Journal Name: High Temperature and Materials Science Journal Issue: 1-3 Vol. 34; ISSN 1080-1278; ISSN HTMSFP
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ADDITIVES
CHEMICAL REACTIONS
DENSITY
NITROGEN
OXYNITRATES
SILICON
SILICON NITRIDES
SYNTHESIS
YTTRIUM COMPOUNDS
YTTRIUM OXIDES
YTTRIUM SILICATES