The role of fluorine in glass formation in the Ca-Si-Al-O-N system

Amir Reza Hanifi, Annaik Genson, Michael J. Pomeroy, Stuart Hampshire

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

Abstract

Oxynitride glasses are found as grain boundary phases in silicon nitride ceramics. They are effectively alumino-silicate glasses in which nitrogen substitutes for oxygen in the glass network, and this causes increases in glass transition and softening temperatures, viscosities (by two to three orders of magnitude), elastic moduli and microhardness. Calcium silicate-based glasses containing fluorine are known to have useful characteristics as potential bioactive materials. Therefore, the combination of both nitrogen and fluorine additions to these glasses may give useful glasses with enhanced mechanical stability for use in biomedical applications. This paper reports glass formation and evaluation of glass properties in the Ca-Si-Al-O-N-F system. Within the previously defined Ca-Si-Al-O-N glass forming region at 20 eq.% N, homogeneous, dense glasses are formed. However, addition of fluorine affects glass formation and reactivity of the glass melts and can lead to fluorine loss as SiF4, and also nitrogen loss. As these gases evolve, bubbles are formed in the glass. The compositional limits for both dense and porous glass formation at 5 eq.% F have been mapped. At high fluorine contents under conditions when Ca-F bonding is favoured, CaF2 crystals precipitate in the glass. The maximum fluorine content found in this system is 7 eq% at a composition Ca 28Si51Al21O73N20F 7. The role of the different cations in these oxyfluoro-nitride glasses is discussed.

Original languageEnglish
Title of host publicationMechanical Properties and Performance of Engineering Ceramics and Composites III - A Collection of Papers Presented at the 31st International Conference on Advanced Ceramics and Composites
Pages337-346
Number of pages10
Edition2
Publication statusPublished - 2008
Event31st International Conference on Advanced Ceramics and Composites - Daytona Beach, FL, United States
Duration: 21 Jan 200726 Jan 2007

Publication series

NameCeramic Engineering and Science Proceedings
Number2
Volume28
ISSN (Print)0196-6219

Conference

Conference31st International Conference on Advanced Ceramics and Composites
Country/TerritoryUnited States
CityDaytona Beach, FL
Period21/01/0726/01/07

Fingerprint

Dive into the research topics of 'The role of fluorine in glass formation in the Ca-Si-Al-O-N system'. Together they form a unique fingerprint.

Cite this