纯水薄液膜下Q235钢潮湿时间的影响因素和腐蚀速度的磁阻研究

以温度、相对湿度和浸润时间为影响因素，研究了纯水薄液膜下Q235钢潮湿时间的影响规律，结合磁阻探头技术和作者提出的积分过滤算法（IFA），分析了腐蚀早期阶段的腐蚀速度变化规律。首先将数据挖掘技术中的标准化处理引入了多变量影响因素分析，显著提高了结果的准确性。研究表明，温度和湿度对碳钢潮湿时间的影响远较浸润时间为大，且温度的影响与试样表面有无腐蚀产物相关。随着温度的提高，温度对清洁试样潮湿时间的影响逐渐加大，大致在20 ℃左右出现明显的转折；湿度对清洁试样潮湿时间的影响则随着温度的升高逐渐下降。通过磁阻探头技术计算得到的腐蚀速度的聚类分析，以20 ℃和相对湿度80%为分界点，大致将腐蚀速度分为两个区，即低和高腐蚀速度区，两区的腐蚀速度相差约4 倍左右。在低腐蚀速度区，实验观察到腐蚀初期可标识腐蚀历程转变的磁阻探头寿命单元（PLU）平台，而相应PLU平台在高腐蚀速度区则不明显，对相关的腐蚀机理作了初步的讨论。

CONTROL FACTORS OF TIME OF WETNESS AND IRP CORROSION RATE FOR Q235 STEEL UNDER PURE WATER THIN FILM

With a series of factors such as time of immersion (TOI), temperature (Temp) and relative humidity (RH), the time of wetness (TOW) of Q235 steel covered by pure water thin film is investigated. The effect of the three factors on corrosion rate is also studied by Inductive Resistance Probe (IRP) measurement and Integration Filter Algorithm (IFA) previously implemented by the author. Standardization protocol (data mining technique) for multivariate analysis of variance is introduced in order to improve the accuracy of TOW linear regression model. The results prove the successful adoption of standardization protocol. Temperature plays a more important role than the humidity in shortening TOW for clean samples at elevated temperature. Around 20 ℃, a significant change of temperature effect on TOW is observed. IRP measurement plus IFA corrosion rate calculation confirms the judgment on temperature effect. Corrosion rate could be clustered into two groups( high and low zone) around the thresholds of 20 ℃ and RH 80% based on cluster analysis on corrosion rate. Quantitative evaluation on corrosion rate between high and low corrosion rate zones shows 4 times difference. Plateau in the very early stage of PLU movement over time of low corrosion rate zone is recorded at first time. However, no PLU plateau is observed for system at higher temperature than 20 ℃ and/or higher RH than 80%. A primary reasoning about this PLU plateau is assumed to be bounded with corrosion rate which is the function of temperature and humidity. This interesting and impressive PLU plateau could indicate the possible composition and/or structure transformation of corrosion product layer under thin liquid film and deserves more effort in future work.