Study of the TiO2-H2O-B2O3 Ternary System at 7.7 GPa and High Temperatures

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• 作者：Rommulo V. Concei&ccedil ; ã ; o ; Sé ; rgio R. S. Soares ; Naira M. Balzaretti ; Altair S. Pereira ; Tania M. H. Costa ; Má ; rcia R. Gallas ; and Joã ; o A. H. da Jornada
• 刊名：Chemistry of Materials
• 出版年：2002
• 出版时间：January 2002
• 年：2002
• 卷：14
• 期：1
• 页码：130 - 134
• 全文大小：70K
• 年卷期：v.14,no.1(January 2002)
• ISSN：1520-5002

文摘

The TiO₂-H₂O-B₂O₃ ternary system was studied at high pressure (7.7 GPa) and hightemperatures, and a phase diagram is proposed. Depending on the initial stoichiometricconditions, Raman spectral analysis identified rutile, TiO₂-II, H₃BO₃, HBO₂, and B₂O₃ asthe crystalline stable phases, and an amorphous phase constituted by B, Ti, and O. Theeutectic point of this system was identified to be at around 400 mages/entities/deg.gif">C. Two piercing pointswere located at around 600 and 1100 mages/entities/deg.gif">C, identified by the stabilization of HBO₂ rather thanH₃BO₃, and B₂O₃ rather than HBO₂, respectively. This study shows that TiB₂ sintering athigh pressure can be compromised by the presence of oxide-bearing phases that decreasethe eutectic point of the system. This phenomenon can produce a liquid that works as amedium for transporting material, producing grain growth, which compromises the borideproperties.