電解海水用鎳基C-276合金之侵蝕研究

Study on The Etching Damage of Alloy C-276 in Sea Water Electrolizer

鎳基C-276材料用於電廠海水電解設備之陰極板，經長期使用發現有損壞情形。本研究旨在探討各種可能導致損壞之原因，俾提供極板整修之依據。首先進行實驗室模擬放電試驗，以探究短路是否為電極損壞之原因。此外亦進行陰極定電位試驗，以探討氫氣釋放對電極損壞之影響。現場及模擬之試樣，以下列各種方式進行分析：以高溫萃取定氫法分析氫含量、以XRD分析材料之相變態及晶格變化、以ESCA作材料表面分析。重要之結果如下：1. 由模擬試驗推測陰極板穿孔是短路放電所致。2. 表面之侵蝕現象，可能是因電極長期受到初生態氫對鎳、鉻及鉬之氧化物產生還原性溶解之化學作用，及氫氣泡對電極產生之機械侵蝕作用。

Nickel based alloy was used as the cathodic electrode in the facility of sea water eletrolysis in power plant, some corrosive phenomena were found after two-year operation. An arcing test was conducted in the laboratory to simulate the field phenomena. A test performed under a cathodic potential was also used to study the effect of the release of hydrogen on this phenomenon. The samples of field and laboratory were investigated by the following techniques: SEM, XRD, ESCA etc. Some conclusions can be drawn as the following: (1)The perforation of the electrode is most probably caused by an arcing between the cathode and its neighboring anode. (2)The etching phenomena of the electrode can be explained by the chemical effect of hvdrogen reduction, and the mechenical effect of hydrogen bubble on the electrode.