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| 題名: | 以微電鍍法製備鋅銅合金微結構 |
| 作者: | 李盈穀;Lee, Ying-Ku |
| 貢獻者: | 機械工程學系 |
| 關鍵詞: | 微電鍍法;鋅銅合金 |
| 日期: | 2020-08-24 |
| 上傳時間: | 2020-09-02 19:15:15 (UTC+8) |
| 出版者: | 國立中央大學 |
| 摘要: | 本研究以微陽極導引電鍍法製作微結構。電鍍系統採用玻璃E管包覆線徑125 μm之白金絲為陽極，以PVC包覆之0.643 mm線徑銅線為作為陰極，於含硫酸銅、硫酸鋅、檸檬酸鈉與硫酸鈉作為輔助電解質之鍍浴中進行電鍍，期望製作出可生物降解之富含鋅之鋅銅合金微結構。研究目標，首先以掃描電子顯微鏡(Scanning Electron Microscope, SEM)探討鍍原始浴中依下列順序改變參數對微結構表面形貌之影響，1.添加不同濃度硫酸鈉(0.15 M、0.30 M與0.45 M) 2.將鍍浴酸鹼值由4.9改變至6.5 3.添加1000ppm聚乙二醇，以改善微結構表面形貌作為最佳化之目標電鍍條件，發現添加0.15M硫酸鈉、鍍浴酸鹼值調整至6.5與不添加聚乙二醇等參數可獲得最佳之表面形貌。
固定上述條件作為最佳條件，以獲得富鋅之鋅銅合金為目標，先降低鍍浴中硫酸銅濃度後再增加硫酸鋅濃度，透過提高鋅銅比[Zn2+/Cu2+]來探討其對表面形貌(SEM)、化學成分分布(Energy-dispersive X-ray spectroscopy, EDS)之mapping與line scan及對晶體結構(X-ray diffractometer，XRD)之影響，並透過循環伏安法(cyclic voltammetry, CV）分別解析鍍浴中銅離子、鋅離子之還原機制。
結果顯示：添加0.15M之硫酸鈉後進行電鍍，可以增加成核密度以改善微結構表面形貌，但若添加更多(0.30、0.45 M)之硫酸鈉會導致瘤狀物覆蓋面積再次增加。將酸鹼值調整至6.5，可顯著改變螯合物在鍍浴中之分率，當螯合物種類由Cu2CitH4-取代Cu2CitH3-時會導致析鍍時銅還原量大幅減少，而瘤狀物因此減少而改善微結構形貌。聚乙二醇添加則使微結構變細，但微結構表面形貌轉為粗糙。
當鋅銅比[Zn2+/Cu2+]達到50.00及66.67時，微結構之鋅別含量達到81± 2 at. %及85± 1 at. %，且橫截面之EDS line scan及mapping結果顯示其組成內外均勻，經光學顯微鏡(Optical Microscope, OM)觀察其橫截面與縱剖面之型態緻密，裂紋及孔洞較鋅銅比[Zn2+/Cu2+]低時少。晶體結構分析顯示：鍍浴鋅銅比[Zn2+/Cu2+]為6.67及11.11時，其對應結構分別為β CuZn相+ γ Cu5Zn8相二相與γ Cu5Zn8相+ ε CuZn5相二相；而鋅銅比[Zn2+/Cu2+]為33.33、50.00及66.67時，其對應結構皆為ε CuZn5單一相。
以奈米壓痕儀測量機械性質，鋅銅比[Zn2+/Cu2+]為50.00及66.67時所析鍍之微結構硬度可達到為2.91 ± 0.25 GPa及2.86 ± 0.29GPa，楊氏模數為47.21 ± 5. 37 GPa與50.25 ± 2.27 GPa，擁有較佳之機械性質；以電化學分析量測其抗蝕性能，測得腐蝕電流密度分別為0. 178 mA/cm2與2.818 mA/cm2。
;In this study, the micro-anode guided electroplating method was used to fabricate the Zn-Cu alloy microstructure. The electroplating system uses glass -tube coated platinum wire with a diameter of 125 μm as the anode, and PVC-coated copper wire with a diameter of 0.643 mm as the cathode, and contains copper sulfate, zinc sulfate, sodium citrate and sodium sulfate as auxiliary electrolytes in bath.It is expected to produce a biodegradable Zinc-rich Zn-Cu alloy microstructure. The research goal is to use Scanning Electron Microscope (SEM) to explore the effect of changing the parameters on the microstructure surface morphology in the original plating bath in the following order: 1. Add different concentrations of sodium sulfate (0.15 M, 0.30 M and 0.45 M ) 2. Change the pH value of the plating bath from 4.9 to 6.5 3. Add 1000ppm polyethylene glycol to improve the microstructure surface morphology as the optimized target. It was found that 0.15M sodium sulfate and plating bath acid and alkali were added and adjust the pH value to 6.5 to obtain the best surface morphology.
Fix the above conditions as the best conditions to obtain Zinc-rich Zn-Cu alloy as the goal, first reduce the concentration of copper sulfate in the plating bath and then increase the concentration of zinc sulfate, by increasing the ratio of zinc to copper [Zn2+/Cu2+] to analysis surface morphology (SEM), chemical composition(Energy-dispersive X-ray spectroscopy, EDS) mapping and line scan and the effect on crystal structure (X-ray diffractometer, XRD) of microstructure.Through cyclic voltammetry (cyclic voltammetry, CV )to analyze the reduction mechanism of Cu2+ and Zn2+ in the plating bath.
The results show that electroplating after adding 0.15 M sodium sulfate can increase the nucleation density to improve the microstructure surface morphology .Adjusting the pH value to 6.5 with ammonia can significantly change the fraction of the chelate compound in the plating bath. When Cu2CitH4- is substituted for Cu2CitH3-, the amount of copper reduction during plating will be greatly reduced. The microstructure morphology is improved. The addition of polyethylene glycol made the microstructure thinner, the surface morphology of the microstructure turned rough.
When the [Zn2+/Cu2+] reaches 50.00 and 66.67, the zinc content of the microstructure reaches 81± 2 at.% and 85± 1 at. %, and the EDS line scan and mapping results of the cross section show uniform distribution of composition.Observed by optical microscope (Optical Microscope, OM), cross-section of structure is dense if [Zn2+/Cu2+] higher than 33.33 .Higher [Zn2+/Cu2+] in bath leads less cracks and holes. Crystal structure analysis shows that when the [Zn2+/Cu2+] is 6.67 and 11.11, the corresponding structures are β CuZn phase + γ Cu5Zn8 phase and γ Cu5Zn8 phase + ε CuZn5 phase. When [Zn2+/Cu2+] is 33.33, 50.00 and 66.67, the corresponding structures are all ε CuZn5 phases.
The mechanical properties were measured with nanoindenter. When the [Zn2+/Cu2+] is 50.00 and 66.67, the hardness of microstructure can reach 2.91 ± 0.25 GPa and 2.86 ± 0.29 GPa, and the Young′s modulus is 47.21 ± 5. 37 GPa and 50.25 ± 2.27 GPa; the corrosion resistance is measured by electrochemical analysis, and the measured corrosion current density is 0.31 mA/cm2 and 0.45 mA/cm2. |
| 顯示於類別: | [機械工程研究所] 博碩士論文
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