The coastal city of Karachi is an imperative part of China–Pakistan Economic Corridor, which is integrated with the modern maritime silk route of the 21st century. This paper presents the corrosion mapping and physicochemical studies of galvanized steel corrosion exposed at the urban, industrial, and marine test sites located in the Karachi coastal city from July 2018 to June 2019. Tests have been performed to determine chloride, sulfur dioxide, time of wetness (TOW), and corrosion rates as per ISO protocols 9223 and 9225, and ASTM standards G1, G50, G140‐02, D4458‐94, and D2010. All test sites have been assigned the C5+ corrosivity category, based on corrosion rates of the galvanized steel, which is not completely in line with the corrosivity category derived from atmospheric pollutants and TOW values for these test sites. SEM/EDS, XRD, and FTIR have characterized the presence of simonkolleite, hydrozincite, and zincite at nearly all the test sites, whereas gordaite is only detected at the marine test sites. Zinc(I) chlorohydroxysulfate is also observed at an urban test site. This study has furnished a novel product of a galvanized steel corrosion map for Karachi, Pakistan.

中文翻译：

---

城市，工业和海洋环境中镀锌钢板腐蚀的物理化学研究以及卡拉奇市的腐蚀图：21世纪现代海上丝绸之路的重要沿海城市

沿海城市卡拉奇是中巴经济走廊的重要组成部分，该走廊与21世纪的现代海上丝绸之路融为一体。本文介绍了2018年7月至2019年6月在卡拉奇沿海城市的城市，工业和海洋测试地点暴露的镀锌钢板腐蚀的腐蚀图和理化研究。已经进行了测试以确定氯化物，二氧化硫，符合ISO协议9223和9225以及ASTM标准G1，G50，G140-02，D4458-94和D2010的湿度（TOW）和腐蚀速率。根据镀锌钢的腐蚀速率，所有测试场所都被指定为C5 +腐蚀性类别，这与从这些场所的大气污染物和TOW值得出的腐蚀性类别不完全一致。SEM / EDS，XRD，FTIR和FTIR的特征是几乎所有测试地点都存在simonkolleite，水锌矿和锌矿，而仅在海洋测试地点才检测到了辉沸石。在城市测试现场也观察到了氯羟基硫酸锌（I）。这项研究为巴基斯坦卡拉奇提供了镀锌钢板腐蚀图的新产品。