硫酸钠溶液中2024-T3铝合金孔蚀过程的电化学噪声特征

来源期刊：中国有色金属学报2001年第2期

论文作者：张昭 张鉴清 王建明 曹楚南

文章页码：284 - 287

关键词：2024-T3铝合金； 孔蚀； 电化学噪声

Key words：2024-T3 aluminum alloy; pitting, corrosion; electrochemical noise

摘    要：高强度航空铝合金结构材料2024-T3在3.0%(质量分数)Na₂SO₄溶液中发生局部腐蚀的过程中，电位噪声的谱功率密度(SPD)曲线都具有相同的特征，即在极低频下为白噪声，随着频率的升高逐渐转化为1/f^α噪声。相应于一个噪声信号波，有一个腐蚀孔出现。在孔蚀诱导期，白噪声水平升高，截止频率增大，SPD曲线的倾斜段直线斜率小于-20 dB_V/decade，且趋于增大。孔蚀发生后，上述3个参量则各自朝着上述方向的逆方向变化。孔蚀时的Hurst指数( H )小于非孔蚀期的Hurst指数，而孔蚀时的系统分维( D )则大于非孔蚀期的系统分维。

Abstract: The features of electrochemical noise (EN) of high-strength 2024-T3 aluminum alloy in 3.0%(mass fraction)Na₂SO₄ solution during pitting corrosion have been investigated. The results show that all the EN observed are low frequency noises and the white noise ( P_W ) which is independent of frequency in the superlow frequency domain and changes to the 1/ f^α noise with the increasing of frequency. Each pit on the surface of corroding electrode corresponds to a sudden jump of electrode potential in time domain. During induced duration of pitting corrosion，the level of white noise and the value of cut-off frequency ( f_C ) increase with the immersion time，while the absolute value of slope of SPD curve's linear part decreases. On the other hand，the above three parameters change in the opposite direction after a pit or a series pits are formed. When a pit is generating the Hurst index is much smaller than that of before or after a pit is formed. Therefore，it is possible to infer the useful information of a corroding electrode according to the value of Hurst index.