热镀锌钢板在青岛不同海水区带的腐蚀行为

开展了热镀锌钢板在青岛不同海水区带的实海腐蚀测试,并利用电化学测试、失重腐蚀测试和扫描电镜研究了镀层的海水腐蚀行为.结果表明,由于镀锌层腐蚀电流密度大,在全浸区流动海水中快速溶解而又难以形成稳定的保护性腐蚀产物膜,耐蚀性最差;镀层在潮差区出现不同程度的生物污损,这可能给镀层带来部分保护,其腐蚀速度比全浸区明显降低;镀层在飞溅区未发生生物污损,但腐蚀速度在三个海水区带中最低,可能与其表面良好的充气条件和腐蚀产物层的阻挡作用有关.与全浸区相比,镀锌层在飞溅区和潮差区的耐蚀性分别提高了94%和37%.

Corrosion Behavior of Hot-Dip Galvanized Sheet Steel in Different Seawater Zones in Qingdao

The commercial hot-dip galvanized sheet steel was investigated for its corrosion behavior in three different seawater zones in Qingdao with electrochemical measurement, weight loss test and SEM. The results indicated that zinc coating exposed to immersion zone dissolved quickly due to high corrosion current density and being hard to form a stable protective film resulting from the corrosion itself, i.e., galvanized steel under such conditions is the poorest one in corrosion resistance. Biofouling often takes place on galvanized steel surface exposed to tidal zone, which may result in partial protection to coating surface at obviously lower corrosion rate than the coupons in immersion zone. The splash zone is the least aggressive of all the seawater zones for galvanized steel with biofouling not occurring. The lowest corrosion rate of galvanized steel in splash zone may relate to the good air ventilation condition on coating surface and the protective film resulting from the oxidation itself. In comparison to the test coupons in immersion zone, the corrosion resistance of those in tidal and splash zones increases by 37% and 94%, respectively.