- 學位論文
以氣相去合金法合成奈米多孔銅之表面形貌與機械性質
Synthesis, Characterization, and Mechanical Properties of Bulk Nanoporous Copper from Vapor Phase Dealloying
摘要
近年來三維多孔結構的金屬材料因為其具有高表面積，又同時具有金屬高導熱性與良好的導電性而被廣泛應用於各種不同領域，因此目前許多研究都致力於製造多孔結構金屬與改善其製程。本研究則採用氣相去合金法成功將銅鋅前驅合金Cu6Zn94、Cu16Zn84以及Cu33Zn67合成出相對密度介於15.7%至47.5%之間，支架尺寸最低達到800 nm的奈米級多孔金屬銅(Nanoporous Copper, NPC)，且經XRD分析沒有其他殘留元素或氧化物，顯示其純度非常高，且能透過不同的去合金溫度調控其支架尺寸。氣相去合金法利用合金中元素間的蒸氣壓差異進行物理性的去合金，不需如化學去合金使用酸鹼溶液進行腐蝕，因此是屬於一項環保且具有發展性的去合金製程。 對於多孔材料而言，機械性質是應用性的一大指標，本研究對氣相去合金法的奈米多孔金屬銅進行壓應力測試，並套用至修正後之Gibson-and-Ashby方程式計算出NPC的支架強度可達到3456MPa，為純銅塊材強度的10倍以上。將支架結構為隨機排列的NPC與3D列印製程得到的規則排列多孔金屬銅比較，NPC的晶格與體心立方堆積結構較為相似，並且表現出與規則排列多孔金屬銅相近的機械強度，顯示出NPC優異的機械強度。 除了機械性質以外，能量吸收能力也是多孔材料的特性之一，NPC的能量吸收能力經計算後最高可以達到183.3 MJ/m3，相比其他的多孔結構金屬銅製程，例如：3D列印法、電子束熔煉法、粉末冶金法以及造孔法等等，都有非常突出的表現。
並列摘要
Three-dimensional open-cell metal foams have been widely used for their high specific surface area, electrical conductivity and thermal conductivity, so recent studies focus on the different methods of synthesizing porous metals. In this study, by applying vapor phase dealloying (VPD) method, open-cell nanoporous coppers (NPCs) with relative densities ranging from 15.7 to 47.5% and the smallest ligament size of 800 nm, respectively, were synthesized from Cu33Zn67, Cu16Zn84, and Cu6Zn94 precursor alloys. Through XRD analysis, there were neither residual elements nor oxidation observed. Moreover, the ligament size of NPC could be controlled by applying different dealloying temperatures. VPD separates elements in precursor alloys by their different vapor pressure, and it does not need additional electrolytes such as strong acid or base. Hence, VPD was an eco-friendly dealloying method to fabricate porous metals. The compression mechanical test results on NPCs showed from the corrected Gibson and Ashby scaling equation, the ligament strength of NPC was up to 3456MPa, which is ten times higher than Cu bulk. Compared to the ordered or periodic Cu foams fabricated from 3D-printing, the deformation behavior of NPCs was close to that of a Body-centered cubic structure; and the yield strength of NPCs, despite of random ligament structures, was comparable to that of other ordered copper foams. The energy absorption capacity of NPCs synthesized from VPD was up to 183.3 MJ/m3, which is an order higher than that of other Cu foam structures fabricated by different methods such as 3D printing, electron beam melting, electro-deposition, chemical dealloying and fiction powder compaction.