Materialization Study on Transformation of Insulated Glass-Ceramic from TFT-LCD Waste Glass and CaF2 Sludge by Thermal Treatment
Date Issued
2010
Date
2010
Author(s)
Fan, Chen-Hsuan
Abstract
This study aimed to use thin film transistor liquid crystal display (TFT-LCD) waste glass and calcium fluoride (CaF2) sludge from optoelectronics industrial wastes as treated materials to produce excellent dielectric (low dielectric loss factor and high dielectric strengths ) and mechanical properties (high flexural strengths and high compressive resistance) by thermal treatment.
There were three experimental stages in this study. (1) Analyzing the fundamental characteristics of wastes, and investigating the effects of varies CaF2/ waste glass ratios on the pouring temperature (PT). (2) The effects of nucleating agent (TiO2) and additives (MgO) on lowest softening temperature (ST) and crystal phases. (3) Based on the results in first and second stages, the third stage focused on the ratios that could potently form the cordierite of MgO-Al2O3-SiO2 (MAS) glass-ceramics system, the effects of temperature on mechanical properties and dielectric properties as well as the assessment of appropriateness of material reutilized from TFT-LCD glass combined with CaF2 sludge as raw materials of insulating glass-ceramic.
The result showed that the lowest PT corresponding to a basicity (CaO/SiO2) of 0.83 under a ratio of CaF2 sludge-waste glass as 50%-50% by weight. The amorphous glass powder prepared by melting and quenching process in the proportion CaF2 sludge-waste glass 30%-70% by weight showed the ST of 899℃ (250℃ lower than other proportions).
TiO2 addition resulted in the decrease of exothermic peak and melting temperature of amorphous glass powder, however it can cause deterioration of dielectric properties and insignificant improvement in mechanical properties. In addition, cordierite phase of the MAS system can be produced by 10% - 20% MgO
III
addition.
The optimal operational conditions to utilize wastes as the potential as insulating glass-ceramics could be found as follows. (1) Co-melting CaF2 sludge and waste glass were in the ratio of 3:7 with MgO addition of 15% by weight. (2) Obtaining amorphous glass powder via quenching treatment (3) One-step sintering and heat treatment at 920℃ for 4h was employed to obtain glass-ceramics. The sintered materials could meet the required properties for insulating glass-ceramics. i.e. they showed flexural strengths up to about 80 Mpa, compressive resistance up to about 220 Mpa, a dielectric loss factor of 0.06 and a dielectric strengths of 7.35 kv/mm.
Subjects
TFT-LCD Waste Glass
Calcium Fluoride Sludge
Insulated Glass-Ceramic
MAS system
Dielectric properties
SDGs
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