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標題: | 以快速冷卻製程及去合金法製備奈米多孔銀之表面形貌與機械性質 Characterization and Mechanical Properties of Nanoporous Silver by Rapid Solidification Process and Dealloying |
作者: | 李芝蓁 Chih-Chen Lee |
指導教授: | 鄭憶中 I-Chung Cheng |
關鍵字: | 細晶粒前驅合金,奈米多孔銀,熱穩定性,機械性質,快速冷卻製程, Fine-grain precursor,nanoporous silver,thermal stability,mechanical properties,melt-spinning, |
出版年 : | 2023 |
學位: | 碩士 |
摘要: | 奈米多孔金屬(NPMs)因其獨特的特性而受到廣泛關注,可應用於多種領域,奈米多孔銀(NP-Ag)具有高電、熱傳導,且在催化以及表面拉曼光譜(SERS)上有良好的表現,因此引起了眾多研究學者的關注。儘管先前的研究已經試圖通過添加其他元素或採用不同的去合金方法來改變NP-Ag的機械性質及微結構,但我們仍需要進一步研究在不同環境條件下NP-Ag的機械穩定性。考慮到潛在應用涉及在高溫過程中進行,因此我們針對NP-Ag在在相對較高的溫度環境下(200°C、400°C和600°C)的形貌和機械性質的穩定性及變化。
根據過去研究顯示,前驅合金(precursor)的晶粒或相(phase)大小會影響到NPMs的強度,本研究透過快速冷卻製程製作出有較細的相的前驅合金薄帶,透過調整不同參數改善薄帶的形貌。接著,我們也證實了,前驅合金的相較小時製作出的NP-Ag,相較於相較大的前驅合金,拉伸強度高了41MPa。根據實驗結果,NP-Ag在200°C的環境下,具有良好的熱穩定性,其表面形貌沒有明顯的改變,支架(ligament)尺寸則略粗了10nm,且在極表層Cu(II)的保護下,可獲得比室溫下的NP-Ag更好的機械性質以及支架連接性,拉伸強度高了6MPa,硬度則高了0.18GPa。然而當NP-Ag在400°C環境中,足夠的高溫使銀原子為了降低表面能而進行擴散與聚集,使支架粗化了338nm,根據過去的研究,支架尺寸越粗,則強度越弱,支架尺寸大幅度的粗化以及表面形貌顯著的改變,使400°C環境中的NP-Ag在拉伸強度上下降了29MPa,硬度則降低了0.07GPa。 Nanoporous metals have garnered significant attention due to their unique properties and application in various fields. Nanoporous silver (NP-Ag) has been noted for its high electrical and thermal conductivity and excellent performance in catalysis and surface-enhanced Raman spectroscopy (SERS), making it a subject of interest among researchers. Despite previous attempts to improve the mechanical properties of NP-Ag by adding elements or other dealloying methods, further research is needed to investigate the stability of NP-Ag in different environmental conditions. However, further research is needed to investigate the mechanical stability of NP-Ag under different environmental conditions. Considering potential applications involving high-temperature processes, we studied the stability and changes in the morphology and mechanical properties of NP-Ag at higher temperatures (200°C, 400°C, and 600°C). Past research has shown that the grain or phase size of the precursor alloy affects the strength of nanoporous metals. In this study, we produced the precursor(ribbon) with smaller phases through melt-spinning and improved the ribbon morphology by adjusting various parameters. We also confirmed that NP-Ag fabricated from precursor alloys with smaller phases exhibited a higher tensile strength compared to those with larger phases, with an increase of 41 MPa. Experimental results demonstrated that NP-Ag showed good thermal stability at 200°C, with a slight increase of 10 nm in ligament size. Moreover, under the protection of a Cu(II) surface layer, NP-Ag subjected to the 200°C environment exhibited improved mechanical properties and ligament connectivity with an increased tensile strength of 6 MPa and hardness of 0.18 GPa. However, when NP-Ag was exposed to a 400°C environment, the elevated temperature resulted in a significant coarsening of ligaments by 338 nm. The substantial coarsening of ligament size and significant changes in surface morphology at 400°C led to a decrease in tensile strength by 29 MPa and hardness by 0.07 GPa. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/88230 |
DOI: | 10.6342/NTU202301806 |
全文授權: | 同意授權(全球公開) |
顯示於系所單位: | 機械工程學系 |
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