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URN etd-0721105-201644 Statistics This thesis had been viewed 3743 times. Download 2593 times. Author Wei-Che Tsai Author's Email Address email@example.com Department Materials Engineering Year 2004 Semester 2 Degree Master Type of Document Master's Thesis Language zh-TW.Big5 Chinese Page Count 140 Title Phase Transformation and Properties of MgO-ZnO-Al2O3-SiO2 Glass-Ceramics Keyword young's modulus vickers hardness three-stage heat treatment surface roughness spinel-enstatite magnetic disk substrate glass-ceramics glass-ceramics magnetic disk substrate spinel-enstatite surface roughness three-stage heat treatment vickers hardness young's modulus Abstract Nanocrystalline glass-ceramics with high elastic modulus, moderate strength, extremely smooth polished surface, and toughness have been developed recently for potential use as magnetic disk substrate in computer hard drives. The major objective of this study is to explore the effect of TiO2 on the crystallization and properties of MgO - ZnO - Al2O3 - SiO2 glass-ceramics. The parent glasses was formed by a melt-quench process, then subjected to nucleation and crystallization heat-treatment to convert it into glass-ceramics containing spinel and enstatite as the major crystalline phases.
The experimental results indicate that while increases in the TiO2 amount enhanced the phase separation of glass, the glass formation ability was reduced. In this study, a three-stage crystallization heat treatment was proposed to decrease the TiO2 amount that is required for fabricating spinel + enstatite glass-ceramics, and inhibiting the precipitation of high-quartz s.s..
The Vickers hardness and Young’s modulus of the glass-ceramics increased obviously with the increase in the heat-treatment temperature. The highest Young’s modulus that can be reached is 155 GPa.
Advisor Committee Jiin-Jyh Shyu - advisor
Hsien-Yin Tsai - co-chair
Yung-Jen Lin - co-chair
Files Date of Defense 2005-06-22 Date of Submission 2005-07-21