nfluences of Particle Size and Sintering Time on Insulating Glass Ceramics Sintered from TFT-LCD Waste Glass and BOF Slag

本研究以薄膜式電晶體型液晶顯示器(Thin Film Transistor-Liquid Crystal Display，TFT-LCD)廢玻璃混合煉鋼產業之副產品轉爐石(Basic Oxygen Furnace Slag，BOF slag)重量比7:3，添加15 wt% 氧化鎂及15 wt% 氧化鋁以不同粒徑成形：D1(D50:11 μm)、D2(D50:25 μm)、D3(D50:59 μm)及不同持溫時間：0.5小時、1小時、2小時，燒結成玻璃陶瓷。討論粒徑及持溫時間對玻璃陶瓷物理、介電、熱學性質及抗折強度影響，並決定符合絕緣玻璃陶瓷規範之最適熱處理條件。本研究析出晶相為頑火輝石(enstatite，MgSiO3)、鈣長石(anorthite，CaAl2Si2O8)、矽灰石(wollastonite，CaSiO3)及鎂橄欖石(forsterite，Mg2SiO4)。 小粒徑D1及燒結時間2小時，使試樣於較低溫緻密及結晶，且能提升抗折強度；此外，燒結2小時提升D1之抗折強度幅度較D2及D3高。 介電性質影響則分為結晶前與結晶後。結晶前D1因試樣較緻密，介電常數及品質因子(250)較高；但結晶後，不同粒徑之介電常數無差異，約介於9-10，然而品質因子皆大幅下降近80%。隨著溫度上升，高品質因子晶相大量析出後，品質因子才些微上升。於900°C燒結2小時品質因子較0.5及1小時低，推測是燒結2小時產生較多頑火輝石之故，且較多頑火輝石也使熱脹係數相對較高。故延長燒結時間改變晶相強度，而影響玻璃陶瓷性質。 以符合絕緣玻璃陶瓷性質規範而言，最適操作條件為D1燒結900°C，持溫0.5小時，該抗折強度158.8MPa，介電常數10.2，品質因子100.1；燒結2小時雖能提高抗折強度至約200 MPa，但品質因子並不符合。較小粒徑D1具較優良抗折強度及品質因子；而延長燒結時間雖提高抗折強度，但無法提升品質因子。依再利用而言，於廢棄物燒結成玻璃陶瓷，降低粒徑較延長燒結時間更具效益性及應用性。The study aims to decide the optimal heat treatment for reusing the glass ceramics in insulating. Influence of particle size: D1(D50:11 μm), D2(D50:25 μm), D3(D50:59 μm) and sintering time: 0.5 hour, 1 hour, 2 hours on physical properties, dielectric properties and bending strength are considered. The glass ceramics sintered from TFT-LCD waste glass (Thin Film Transistor-Liquid Crystal Display) mixed BOF slag (Basic Oxygen Furnace Slag) with weight ratios 7:3, adding 15 wt% MgO and 15 wt% Al2O3. The main crystalline are enstatite(MgSiO3), anorthite(CaAl2Si2O8), wollastonite(CaSiO3) and forsterite(Mg2SiO4). Results show that glass ceramics of D1 and sintering 2 hours ocurr densification, crystallization and higher bending strength at lower temperature. Before crystallization, dielectric constant and quality factor (Q factor) of D1 is higher because glass ceramics of D1 are much denser. After crystallization, there are no effects of particle size on dielectric constant, but Q factor decreases about 80%. However, as sintering temperature rise and crystalline having high Q factor appear, Q factor increases smoothly. Moreover, longer sintering time causes the occurrence of enstatite, which lead to Q factor drops and coefficient of thermal expansion increase. On the effect of particle size, D1 performe better in bending strength and Q factor than D2. On sitering time, though longer sintering time lead to higher bending strength, Q factor cannot increase during temperature rising. As a result, D1, 900°C, 0.5hour which have well bending strength 158.8MPa, dielectric constant 10.2 and Q factor 100.1 is the most suitable heat treatment for insulating glass ceramics. On the aspect of reusing, smaller particle is more effective and economics than longer sintering time