由於成本低廉、易於量產且在多方面皆符合雙極板的特性需求，不鏽鋼成為目前雙極板材料研究的熱門選項。然而儘管不鏽鋼表面的金屬氧化層能保護基材免於腐蝕的發生，使雙極板能夠在PEMFC的酸性環境中良好地運作，其高阻抗卻會導致雙極板與氣體擴散層間的接觸電阻提高，從而降低PEMFC的功率輸出。因此在維持不鏽鋼材料優異抗蝕性的同時，如何降低其接觸電阻乃是不鏽鋼作為雙極板材料的主要研究目標。
市售的316L不鏽鋼雖然在PEMFC模擬環境測試中表現出良好的腐蝕性質，卻具有相對高的接觸電阻。因此本研究以電化學氮化法對316L不鏽鋼進行表面改質，於其表面生成抗蝕性與導電性均佳的鉻氮化物保護層，以符合PEMFC雙極板的特性需求。
為了提高不鏽鋼表面的Cr/Fe比以利鉻氮化物生成，316L不鏽鋼片在進行電化學氮化前先以70°C，3.0M的硝酸酸洗2小時，去除不鏽鋼表面的鐵氧化物。接著酸洗後的不鏽鋼片會在硝酸與硝酸鉀的混合溶液中於室溫下進行電化學氮化。PEMFC模擬加速測試的結果表明，酸洗後在0.1M HNO3 + 0.5M KNO3溶液中以-0.25V氮化2小時的不鏽鋼試片有最佳的腐蝕性能，其在陰極與陽極測試的平衡電流分別為23.3與-30.7 nA/cm2。而在接觸電阻方面，該條件下氮化的試片於140N/cm2下的接觸電阻為16.7mΩ-cm2，相較於未處理之316L不鏽鋼片的86.3mΩ-cm2下降了5倍以上。由本研究的結果來看，電化學氮化法在不鏽鋼雙極板材料表面處理上具有相當高的應用潛力。

Bipolar plates are one of the most important components in PEMFC. To support membrane electrode assembly (MEA) and connecting single cells, stainless steels are promising candidates because of its mechanical strength, high conductivity, and of course, relatively low cost. However, one of the drawbacks of stainless steel bipolar plates is the high interfacial contact resistance (ICR) due to their surface oxide film. Though providing good protection for the base alloy from further corrosion, the oxide film will definitely decrease the conductivity. Commercially available 316L steel shows high ICR and high corrosion resistance in simulated PEMFC environments. In this work, 316L steel was electrochemically nitrided to form a corrosion-resistant and electrically conductive chromium nitride film.
To assist the formation of chromium nitride layer, steels were first acid washed in 3.0M HNO3 solution at 70°C for 2 hours to improve the Cr/Fe ratio. Then the steels were electrochemically nitrided in a mixture of HNO3 and KNO3 solutions at room temperature to obtain the surface chromium nitride film. In the simulated PEMFC tests, the steel which had been acid-washed and electrochemically nitrided in 0.1M HNO3 + 0.5M KNO3 at -0.25V for 2 hours showed the lowest current. The results of simulated cathode and anode tests were 23.3 and -30.7 nA/cm2. And the ICR of the nitrided steel decreased to 16.7mΩ-cm2. With such outstanding performances in these tests, it is clear that electrochemical nitridation is a promising way to modify stainless steel for PEMFC bipolar plates.

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