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|標題:||Crystal Structure and Growth Morphology of Interlayer Between Boron Oxide and Alumina Substrate
Feng, Lu Yu
|關鍵字:||暫態液相接合;transient liquid phase bonding;針狀結晶;介穩定相3Al2O3-B2O3;needle-like structure;metastable 3Al2O3-B2O3 phase||出版社:||材料工程學研究所||摘要:||
It was found recently that the transient liquid phase bonding of alumina via boron oxide interlayer results in a needle-like structure at joint. In this research the growth morphology and crystal structure of the interfacial compounds at 900C for various joining time have been investigated. In addition, the interfacial structure of the joint at 800C and 15 hrs has also been studied, while the maximum joining strength of 155 MPa was found at this joining condition.
Alumina bulks coated with 3m thick boron oxide at one side have been stacked in pair by facing the coated sides. The loading was set as 15 kPa. The joining times at 900C are 2, 6, 15, 24 hrs and it is 15 hrs at 800C. The morphology and crystal analysis of the joined alumina bulks were carried out in aid with scanning electron microscope and transmission microscope including selected area diffraction.
The appearance of three compounds 3Al2O3-B2O3, 2Al2O3-B2O3 and 9Al2O3-2B2O3 is verified by means of diffraction pattern analysis. It is found in this study that at 900C the interface is mostly occupied by the cloudy metastable 3Al2O3-B2O3 phase, while joining for 2 hrs. The stable 2Al2O3-B2O3 and 9Al2O3-2B2O3 appear with increasing time, while the later forms later. The shape of both stable compounds is needle-like and they grow along the  direction detected from selected area diffraction imaging. It indicates a good coherency between the compound needles and substrate grains that no obvious boundary between them was observed.
The strongest joint made at 800C for 15 hrs posses a more complicated morphology, which increases the difficulty to distinguish the microstructure of these compounds. However, all three compounds mentioned previously were detected.
由選區繞射分析，證實了3種化合物3Al2O3-B2O3、2Al2O3-B2O3 和9Al2O3-2B2O3的存在，結果顯示，900℃接合時間為2hr 以內，界面主要為介穩定相3Al2O3-B2O3。隨著時間增長而形成穩定相2 Al2O3-B2O3及9Al2O3-2B2O3。隨著接合時間的增加，這兩種穩定相會形成針狀，由選區繞射圖形研判，針狀結晶係沿著方向成長。由SEM照片發現，針狀物與氧化鋁之間形成良好的結合，無法判別針狀物與氧化鋁基材之間的晶界
|Appears in Collections:||材料科學與工程學系|
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