此研究係以AISI 1045、AISI 1080碳鋼以及AA 7075鋁合金為基材，分別利用粉浴法及電鍍法在基材表面製備耐蝕且導電之富鉻鍍層，作為改善基材抗蝕性、導電性及疏水性之表面改質製程，並應用在燃料電池雙極板。由於碳鋼熔點較高，適合以較高的溫度在表面生成富鉻鍍層，故使用粉浴製程作為處理並搭配電鍍細晶粒鎳鍍層作為活化處理降低粉浴操作溫度；而鋁合金熔點較低，較適合使用電鍍法製備鉻碳鍍層，唯鋁合金基材難以直接電鍍鉻碳合金，需要搭配適當中間層才能形成均勻鍍層。研究結果顯示真空粉浴處理之碳鋼試片後發現表面形成緻密富鉻鍍層，主要組成相為碳化鉻(CrxNy)及氮化鉻(CrxCy)；其富鉻鍍層能有效提昇耐蝕性、導電性及疏水性。以AA 7075鋁合金為基材，以電鍍鎳、置換鋅或電鍍銅作為中間層後電鍍富鉻鍍層，試片之富鉻鍍層組成相主要為金屬鉻(Cr)及碳化鉻(CrxCy)，其中電鍍銅中間層試片之表面鉻碳鍍層連續且緻密，因此具有較佳的抗蝕性及導電性。整體而言，非真空粉浴技術製備之碳鋼試片其耐蝕性、導電性與疏水性皆優於以電鍍鉻碳處理之鋁合金試片，較適合應用於燃料電池金屬雙極板。

The main object of this study is to improve the corrosion resistance, electric conductivity and hydrophobicity of AA7075 aluminum alloy and carbon steels (AISI 1045, 1080) by eletrodeposition and pack cementation, respectively, to produce a Cr-rich (Cr-C alloy) coating on the substrates for the demands of proton exchange membrane fuel cell (PEMFC). The carbon steels were treated with pack cementation to form a Cr-rich coating because the melting point of carbon steels is high enough to sustain thermal reaction process. Electroplating a Ni coating with fine grain size on the carbon steels can activate the surface and lower the pack cementation temperature. The electroplating process is more suitable to deposit Cr-rich coating on Al alloys due to their low melting point, but it is difficult to electroplate a uniform Cr-C coating on aluminum alloys without a interlayer. Experimental results showed that a compact and crack-free Cr-rich coating was formed on the carbon steels after pack cementation, which increased the corrosion resistance, electric conductivity, and hydrophobicity of the steels. The main constituent phases of the chromized layer are chromium-carbides and chromium-nitrides. The Cr-rich coating, electroplated on the Al alloys with different interlayers (Ni, Zn, or Cu coating), were composed of chromium and chromium-carbide. Among these Cr-electroplated Al alloys, the specimen with copper interlayer processes formed a dense and continuous Cr-C alloy layer and therefore has the higher corrosion resistance, electric conductivity, and hydrophobicity. Conclusively, the corrosion resistance, electric conductivity, and hydrophobicity of the chromized carbon steels are superior to those of Cr-electroplated Al alloys. Therefore, the carbon steels improved with pack chromization are more suitable to applied to metallic bipolar plates.

摘要 ....................................................................................... ii
Abstract .................................................................................. iii
目錄 ....................................................................................... iv
表目錄 ..................................................................................... vii
圖目錄 ..................................................................................... viii
1. 緒論 .............................................................................. 1
1.1研究背景 ........................................................................... 1
1.2研究目的 ........................................................................... 2
2. 文獻回顧及理論 ...................................................................... 4
2.1燃料電池發電原理 .................................................................... 4
2.2燃料電池種類及組成元件 ............................................................... 6
2.2.1燃料電池種類 ...................................................................... 6
2.2.2質子交換膜燃料電池組成元件 .......................................................... 8
2.3金屬雙極板性能需求 ................................................................... 10
2.3.1抗蝕性及電化學檢測 ................................................................. 10
2.3.2接觸阻抗 .......................................................................... 16
2.3.3疏水性 ............................................................................ 18
2.4表面改質 ............................................................................ 22
2.4.1粉浴鉻化及電鍍鉻碳鍍層之性質 ......................................................... 22
2.4.2粉浴鉻化製程及擴散反應機構 ........................................................... 23
2.4.3粉浴鉻化之活化原理 .................................................................. 26
2.4.4電鍍鉻碳鍍層之原理 .................................................................. 29
2.4.5電鍍鉻碳鍍層之中間層製備及原理 ........................................................ 30
2.5金屬雙極板發展近況 .................................................................... 33
3. 實驗方法 ............................................................................. 36
3.1實驗流程 ............................................................................. 36
3.2詴片之製備 ........................................................................... 38
3.3粉浴製程 ............................................................................. 39
3.3.1表面活化製程 ........................................................................ 39
3.3.2粉浴鉻化製程 ........................................................................ 39
3.4電鍍製程 .............................................................................. 40
3.4.1中間層製備 .......................................................................... 40
3.4.2電鍍鉻碳製程 ........................................................................ 40
3.5分析與檢測 ............................................................................ 41
3.5.1鍍層結構與組成分析 ................................................................... 41
3.5.2腐蝕性質測詴 ........................................................................ 42
3.5.3接觸阻抗量測 ........................................................................ 43
3.5.4接觸角量測 .......................................................................... 45
3.5.5單電池檢測 .......................................................................... 45
4.結果與討論 ............................................................................. 46
4.1碳鋼之富鉻鍍層特性分析 ................................................................. 46
4.1.1 富鉻鍍層形貌與結構 .................................................................. 46
4.1.2 鉻化鍍層之組成分析 .................................................................. 55
4.1.3 動電位測詴結果分析 .................................................................. 60
4.2鋁合金之富鉻鍍層特性分析................................................................. 64
4.2.1富鉻鍍層形貌與結構 ................................................................... 64
4.2.2 中間層及鉻碳鍍層組成分析 ............................................................. 77
4.2.3 動電位測詴結果分析 .................................................................. 82
4.3 燃料電池操作環境模擬測詴................................................................ 85
4.3.1靜電位測詴結果分析 ................................................................... 85
4.3.2接觸阻抗及疏水性分析 ................................................................. 87
4.4單電池性能分析 ........................................................................ 93
5.結論 .................................................................................. 95
未來展望望 ............................................................................... 96
參考文獻 ................................................................................. 97
自傳......................................................................................105

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