銅鎳擴散層在稀氨水中耐蝕性之研究

The Corrosion Resistance of Copper-Nickel Diffusion Layer in Diluted Ammonia Water

銅底材電鍍鎳或無電鍍鎳後、置入石英管中，抽除空氣後，在氬氣保護下，熱處理800℃ 4小時，可得銅鎳擴散層，由X光繞射與SEM分析，電鍍鎳之銅底材熱處理後，鎳鍍層有鎳銅合金擴散層；無電鍍鎳之銅底材則受熱產生鎳磷析出物（Ni3P）與鎳銅合金擴散層，其中擴散層深度較電鍍鎳試片小。由電化學分析，電鍍鎳試片經熱處理後，在2.0M 稀氨水中有較佳之耐蝕性（Ecorr = -0.452 V vs SCE），有鈍態保護；無電鍍鎳試片熱處理後，在稀氨水中之腐蝕電位為-0.373 V，由極化曲線判斷在鈍態生成時，有孔蝕現象，由光學顯微鏡觀察試片表面形態，確實有孔蝕存在，銅試片在稀氨水中為均勻腐蝕。熱處理之電鍍鎳的銅試片，有改善銅在稀氨水中的抗蝕效果，而無電鍍鎳的銅試片，熱處理後在稀氨水之保護效果較差，推論可能是鎳銅擴散層較薄，且鍍層中有鎳、鎳磷化合物等析出相，引發伽凡尼腐蝕現象所致。

Copper-nickel diffusion layer was prepared by heating nickel-plated copper panel at 800℃ for 4 hours under argon atmosphere. Based upon XRD and SEM analytical results, nickel and copper nickel alloy were observed in coating layer for electroplated sample. For electroless nickel-plated sample, Ni3P was found in addition to nickel and copper nickel alloy in the coating layer. The thickness of diffusion layer was smaller for electrolessly nickel-plated sample as compared with that of electroplated sample. As revealed by electrochemical analytical data, the thickness of copper-nickel diffusion layer is closely related to the corrosion resistance in diluted ammonia water. Pitting corrosion occurred for heat-treated nickel-plated copper samples. Galvanic corrosion was accompanied with pitting corrosion for electrolessly nickel-plated and heat-treated copper sample.