船用钢需钠弧菌附着腐蚀电化学噪声特征分析

Analysis of Electrochemical Noise Characteristics Arising from Hull Steel Corrosion Induced by Vibrio Natriegens

选取船用钢板DH34为研究对象,将试验钢板浸泡于需钠弧菌培养液中和无菌培养液中进行腐蚀试验,对比分析了该材料在需钠弧菌培养液中的腐蚀特征。采用扫描电镜观察腐蚀形貌,结果表明在需钠弧菌培养液中试样发生局部点蚀,而在无菌培养液中则为全面腐蚀。对腐蚀过程进行了噪声电压和噪声电流的采集,时域和频域分析表明:在有需钠弧菌的培养液中,电压噪声功率谱的高频斜率高于-20dB/dec,截止频率大于0.2 Hz,起始两天噪声的点蚀指数接近于1;而在无菌的培养液中,电压噪声功率谱的高频斜率小于-20dB/dec,截止频率低于0.2Hz。需钠弧菌的培养液中噪声电阻值高于无菌培养液中噪声电阻值。点蚀指数、噪声功率谱密度的高频斜率和截止频率可用于判断需钠弧菌附着时船用钢板DH34的腐蚀行为。

The corrosion characteristics of hull steel DH34 exposed in the Vibrio natriegens culture solution and the sterilized culture solution are studied through scanning electron microscope（SEM）and electrochemical noise analysis（ENA）.The pitting of hull steel is developed in Vibrio natrigens solution while the general corrosion is developed in sterilized culture solution.ENA results show that the pitting index values are near to 1on the first two days in Vibrio natriegens culture solution.The slop of potential noise power density spectrum（PDS）on high frequency scale is higher than-20dB/dec and the cutoff frequency is higher than 0.2 Hz in Vibrio natrigens culture solution,while the slop is lower than-20dB/dec and the cut-off frequency is lower than 0.2Hz in sterilized culture solution.The noise resistance in Vibrio natrigens culture solution is higher than that in sterilized culture solution.The pitting index,PDS slop on high frequency scale and cut-off frequency can be applied to the corrosion behavior analysis induced by Vibrio natriegens.