Papers by Keyword: Glass Formation

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Authors: Amir R. Hanifi, Annaik Genson, Michael J. Pomeroy, Stuart Hampshire
Abstract: Ca-Sialon glasses have been known for some time [1] and they are effectively calciumalumino- silicate glasses containing nitrogen which improves their mechanical properties. Calciumalumino- silicate glasses containing fluorine are known to have useful characteristics as potential bioactive materials [2]. Therefore, the combination of both nitrogen and fluorine additions to these glasses may give useful bioglasses with enhanced mechanical stability.Addition of fluorine to oxynitride glasses was not reported previously and this paper gives the first report of the glass forming regions (and evaluation of some properties) in the Ca-Si-Al-O-N-F system. Within the previously defined [1] glass forming region in the Ca-Si-Al-O-N system, homogeneous, dense glasses are formed. Addition of fluorine extends the glass forming region but also increases the reactivity of the glass melts. One major problem is fluorine loss as SiF4, but also loss of nitrogen, which affects the final composition and results in porous samples. To suppress the fluorine loss and CaF2 precipitation, consideration of the ratio of cations to fluorine and the coordination number of Al atoms is important. Discussion of the role of cations in these oxyfluoronitride glasses is presented.
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Authors: Stuart Hampshire, Amir R. Hanifi, Annaik Genson, Michael J. Pomeroy
Abstract: Oxynitride glasses are effectively alumino-silicate glasses in which nitrogen substitutes for oxygen in the glass network, resulting in increases in glass transition and softening temperatures, viscosities (by two to three orders of magnitude), elastic moduli and microhardness. Calcium alumino-silicate 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 bioglasses with enhanced mechanical stability. This paper gives a review of oxynitride glasses and reports glass formation and evaluation of glass properties in the Ca-Si-Al-O-N-F system. Within the previously defined glass forming region in the Ca-Si-Al-O-N system, 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, but also nitrogen loss, and cause bubble formation. At high fluorine and high Ca contents under conditions when Ca- F bonding is favoured, CaF2 crystals precipitate in the glass. It was found that fluorine expands the glass forming region of Ca-Sialon system and facilitates the solution of nitrogen into the melt.
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Authors: P.J. Desré
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Authors: C. Qin, Wei Zhang, Katsuhiko Asami, Hisamichi Kimura, Akihisa Inoue
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Authors: C.C. Hays, Choong Nyun Paul Kim, William L. Johnson
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Authors: H. Tan, Z.P. Lu, Yuan Ping Feng, Yuan Yuan Li
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Authors: Reni Iordanova, Lyubomir Aleksandrov, Angelina Stoyanova, Yanko B. Dimitriev
Abstract: Low melting glasses in the MoO3-Nd2O3-Bi2O3 system were obtained at slow (102 K/s) and high cooling rates (104-105 K/s). The amorphous state of the samples was proved by X-ray diffraction. Comparative analysis of the infrared spectra of the obtained glasses and other available molybdate spectral data was carried out. The structure of glasses with a high MoO3 content was found to consist of corner shared MoO6 units. The increasing of Nd2O3 and Bi2O3 lead to partial transformation of MoO6 to MoO4 units, due to breaking of Mo-O-Mo linkage.
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Authors: Tong Yang Wang, Zhen Xi Sun, Lan Xiang Zhang, Yan Wang
Abstract: In this study, the influence of 0.5 wt.% graphene (Gr) addition on the glass formation and thermal stability of the Al75Ni10Ti10Zr5 alloy during mechanical alloying (MA) process has been investigated. The as-milled products consist of the amorphous phase and a small amount of the AlNi nanocrystals. The results showed that the 0.5 wt.% Gr addition could shorten the amorphization process, indicating the enhancement of the glass forming ability. Moreover, the onset crystallization temperature (Tx1) slightly decreased with prolonging milling time for the as-milled alloys. However, it is worth noting that the Gr addition effectively increased the Tx1 of the as-milled Al-based amorphous composites for the long duration of MA time. The Tx1 values of the as-milled AlNiTiZrGr amorphous composites were more than 1120 K, exhibiting the highly thermal stability.
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