(浙江大學(xué) 化學(xué)系， 杭州 310027)
摘 要: 高強(qiáng)度航空鋁合金結(jié)構(gòu)材料2024-T3在3.0%(質(zhì)量分?jǐn)?shù))Na2SO4溶液中發(fā)生局部腐蝕的過程中，電位噪聲的譜功率密度(SPD)曲線都具有相同的特征，即在極低頻下為白噪聲，隨著頻率的升高逐漸轉(zhuǎn)化為1/fα噪聲。相應(yīng)于一個(gè)噪聲信號(hào)波，有一個(gè)腐蝕孔出現(xiàn)。在孔蝕誘導(dǎo)期，白噪聲水平升高，截止頻率增大，SPD曲線的傾斜段直線斜率小于-20 dBV/decade，且趨于增大。孔蝕發(fā)生后，上述3個(gè)參量則各自朝著上述方向的逆方向變化。孔蝕時(shí)的Hurst指數(shù)( H )小于非孔蝕期的Hurst指數(shù)，而孔蝕時(shí)的系統(tǒng)分維( D )則大于非孔蝕期的系統(tǒng)分維。
關(guān)鍵字: 2024-T3鋁合金； 孔蝕； 電化學(xué)噪聲
pitting corrosion of 2024-T3 aluminum
alloy in 3.0% Na2SO4 solution
（Department of Chemistry， Zhejiang University， Hangzhou 310027， P.R.China）
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 ( PW ) which is independent of frequency in the superlow frequency domain and changes to the 1/ fα 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 ( fC ) 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.
Key words: 2024-T3 aluminum alloy; pitting, corrosion; electrochemical noise
