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Effect of TiO2 addition on the crystallization and tribological properties of MgO-CaO-SiO2-F2O5-F glasses

2008-04-10
Park, Jongee
Öztürk, Abdullah
The kinetic parameters including the activation energy for crystallization (E), the Avrami parameter (n) and frequency factor (v) of a glass in the MgO-CaO-SiO2-P2O5-F system were studied using non-isothermal differential thermal analysis (DTA) with regard to small amount of TiO2 additions. It has been shown that the role of TiO2 changes from a glass network former to a glass network modifier with increasing TiO2 content in this system. The kinetic parameters of the crystallizing phases, apatite and wollastonite, indicated changes accompanied with TiO2 additions, implying that the TiO2 is an effective nucleating agent for promoting the crystallization of apatite and wollastonite. The most effective addition is of about 4 wt% TiO2 in this system. The wear rate and friction coefficient decreased from 1.8 +/- 0.1 to 0.9 +/- 0.2 and 0.87 to 0.77, respectively, when 4 wt% TiO2 was incorporated to the base glass. (C) 2008 Elsevier B.V All rights reserved.