臺灣博碩士論文加值系統

本實驗針對堇青石玻璃,添加晶質及鍛燒後的莫來石作一有系統的研究,
以了解此玻璃陶瓷的燒結性,顯微組織及介電性的變化.實驗結果顯示,堇
青石玻璃中鋁含量高,或莫來石添加量多,則燒結性差,且燒結溫度大
於1000度時,材料的燒結密度反而隨燒結溫度上升而降低.在燒結溫度小
於1000度時,莫來石含量必須小於20wt%,才可獲得緻密的試片,顯微組織也
因燒結溫度不同而有明顯的不同;1000度以下燒結時,堇青石結晶呈樹枝狀
及等軸狀,但燒結溫度大於1000度時堇青石結晶則呈柱狀晶.此外添加的莫
來石,在高溫(1250度)時會部分溶入堇青石玻璃中,影響堇青石玻璃的結晶
行為,若選用2-3um的晶質莫來石及低含鋁堇青石玻璃,配成堇青石-莫來
石(小於20wt%),則可在小於1000度下燒結獲得密度大於2.6g/cm3, 介電值
小於5.6,介電損失小於0.1%的玻璃陶瓷材料.

The sintering behavior,dielectric properties and microstructure
of Cordierite glass crystalline and calcined mullite,were
systematically investigated.Theresults showed that high alumina
content in cordierite composite or high amounts of mullite
addition would impair the sinterability.When sintering
temperatureswere ≧ 1000℃ ,the density of sintered pellets
decreased as temperature increased.When sintered at temperature
were ≦1000℃ ,pellets could be sintered to high density if
mullite content was ≦20wt%.The sintering temperature also
affected themicrostructure.Cordierite crystallize into equi-axed
and dendritic shape if sintered below 1000℃,and into columnar
shape if sintered at ≧ 1000℃.Mullite appeared to partial
dissolve into Cordierite glass at 1250℃.Powder compacts of
cordierite glass with ≦ 20wt% of 2-3 um mullite could be
sintered to ~2.6g/cm3 density with dielectricconstant ≦ 5.6 and
tangent loss ≦0.1%.