【摘要】 为了进一步探索“雾霾天气”和水分对砂土中X80钢电化学腐蚀机理的影响，采用电化学工作站、光学显微镜、扫描电子显微镜（SEM）、能谱仪（EDS）和X射线光电子能谱仪（XPS）测试自然风干状态下含雾霾模拟液（HA溶液）砂土中X80钢的电化学阻抗谱、极化曲线、腐蚀产物和腐蚀形貌，结合砂土的理化性质和电化学阻抗谱理论综合研究了含雾霾模拟液砂土中X80钢的电化学腐蚀行为。结果显示：砂土介质的pH值在6.51～7.03范围内波动，基本呈中性，温度在20℃附近波动，砂土含水量14 d内从初始30%饱和状态逐渐下降为0。阻抗谱为非一个时间常数型。随时间的延长，容抗弧半径先减小后增大，表明砂土对X80钢的腐蚀性先增强后减弱。阻抗模值与相位角随砂土含水量的变化规律，与阻抗谱演变规律一致。6 d后阻抗谱、阻抗模值与相位角在10³～10⁵ Hz频域内，波动较大。根据J_corr,1～12 d时砂土对X80钢的腐蚀等级均在中等以上，13～14 d降为轻微。平均腐蚀速率为1.26×10^-1 mm/a,雾霾模拟液加速了砂土中X80的腐蚀。X80钢表面覆盖了高低不平的深棕黄色腐蚀产物（为铁的氧化物，Fe₂O₃和FeO）,腐蚀产物的厚度平均约150μm,局部区域腐蚀产物厚度达到600μm以上。腐蚀产物呈豹纹状、团絮状、米粒状等形状。局部区域腐蚀较强，形成了较多的腐蚀坑。更多还原

【Abstract】 In recent years, rapid urbanization and industrialization have led to frequent haze events. Corrosive ions carried by atmospheric fine particulate matter(PM_2.5), such as SO₄^2-, NO₃^-, NH₄⁺, and Cl^-, enter soil through rainfall deposition and alter the physicochemical properties and corrosivity of soil. Meanwhile, soil water content is a key factor controlling electrochemical corrosion in soil. X80 high-strength pipeline steel is widely used in major projects such as the West-East Gas Transmission Project. Sandy soil is widely distributed in China, and long-distance transmission pipelines often pass through sandy soil areas.To further investigate the effects of haze weather and moisture on the electrochemical corrosion mechanism of X80 steel in sandy soil, the electrochemical impedance spectroscopy, polarization curves, corrosion products, and corrosion morphology of X80steel in sandy soil containing simulated haze solution（HA solution） under natural air-drying conditions were tested using a CS350H electrochemical workstation, an optical digital microscope, scanning electron microscopy（SEM）, an energy dispersive spectrometer（EDS）, and X-ray photoelectron spectroscopy（XPS）. Combined with the physicochemical properties of sandy soil measured using a soil moisture meter and electrochemical impedance spectroscopy theory, the electrochemical corrosion behavior of X80 steel in sandy soil containing simulated haze solution was comprehensively investigated.The results showed that the pH value of the sandy soil medium fluctuated within the range of 6.51-7.03, indicating an approximately neutral environment, while the temperature fluctuated around 20 ℃. The water content of the sandy soil gradually decreased from the initial 30% saturation state to 0 within 14 d. The impedance spectra did not exhibit a single-time-constant characteristic, and all impedance spectra in the low-frequency region consisted of flattened capacitive arcs. With increasing time, the radius of the capacitive arc first decreased and then increased, indicating that the corrosivity of the sandy soil toward X80 steel first increased and then decreased. The variations in impedance modulus and phase angle with sandy soil water content were consistent with the evolution of the impedance spectra. After 6 d, the impedance spectra, impedance modulus, and phase angle fluctuated significantly in the frequency range of 10³-10⁵ Hz.With prolonged exposure time and the continuous decrease in water content in the sandy soil, the polarization curves of X80 steel shifted upward as a whole. The corrosion current density first increased and then decreased, reaching a peak value of 2.72×10^-5 A/cm² on the 3rd day. According to J_corr, the corrosion grade of X80 steel in sandy soil was moderate or above from 1 to 12 d, and decreased to slight corrosion from 13 to 14 d. The electrochemical corrosion process of X80 steel was jointly affected by the HA solution and the pore structure of the sandy soil. The overall corrosion rate first increased and then decreased, with an order of magnitude ranging from 10^-1 to 10^-2 mm/a. The average corrosion rate was 1.26×10^-1 mm/a, indicating that the simulated haze solution accelerated the corrosion of X80 steel in sandy soil.The surface of X80 steel was covered with uneven dark brownish-yellow corrosion products, which were identified as iron oxides, including Fe₂O₃ and FeO. The average thickness of the corrosion products was approximately 150 μm, and the thickness in local areas exceeded 600 μm. The corrosion products exhibited leopard-like, flocculent, and rice-grain-like morphologies. Severe localized corrosion occurred in some areas, resulting in the formation of numerous corrosion pits. This study clarified the electrochemical corrosion behavior and mechanism of X80 steel in sandy soil containing simulated haze solution under natural air-drying conditions. The results provided important experimental evidence and theoretical support for corrosion prediction, safety protection, and engineering application of buried X80 pipeline steel in sandy soil strata.更多还原