Abstract: ［Objective］To address the long-term corrosion protection requirements for Q235 steelstructures in coastal environments with high salinity and humidity，a comparative study was conducted on the protective performance evolution of two coating systems—bare steel with a primer/intermediate/topcoat system and galvanized steel with another primer/intermediate/topcoat system—under accelerated neutral salt spray and ultraviolet aging conditions. The differences in corrosion resistance behavior and failure mechanisms between the two systems were systematically evaluated，providing an experimental basis for the rational selection of coating systems for steelstructures in coastal regions.［Methods］Through surface analysis，chemical structure changes，and electrochemical tests，the failure mechanism of the two coating systems under accelerated corrosion testconditions were elucidated.［Results］The results showed that the bare steel coating system exhibited superior corrosion resistance and stability compared to the galvanized steel coating system under bothneutral salt spray and UV aging tests. The failure of the bare steel coating system was mainly attributedto chloride ion penetration and photo-oxidation，whereas the failure of the galvanized steel coatingsystem was closely associated with insufficient interfacial stability and localized reactions between thegalvanized layer and penetrating species from the coating.［Conclusion］Considering the performance and failure mechanism of the two coating systems，the bare steel with primer/intermediate/topcoatsystem was recommended for coastal and other highly corrosive environments to improve protectiveperformance，reduce maintenance costs，and ensure the long-term stable operation of coastal infrastructure. 

Key words: Q235 steel, galvanized steel, coating, neutral salt spray test, UV aging test, failure mechanism

摘要： 【目的】针对沿海高盐高湿环境下 Q235钢结构长期腐蚀防控需求，对比研究裸钢-底中面涂层体系与裸钢镀锌-底中面涂层体系在中性盐雾和紫外老化加速条件下的防护性能演变规律，系统评估 2种涂层体系的耐腐蚀行为差异及其失效机理，为沿海环境下钢结构涂层体系的合理选型提供实验依据。【方法】通过表面分析、化学结构变化以及电化学测试，揭示了 2种涂层体系在中性盐雾试验和紫外老化加速试验条件下的失效机制。【结果】裸钢-底中面涂层体系在中性盐雾试验和紫外老化试验中展现出更优的耐腐蚀性和稳定性。其失效主要源于氯离子渗透和光氧化反应；裸钢镀锌-底中面涂层体系失效则与界面稳定性不足和镀锌层与涂层渗透物质发生局部反应密切相关。【结论】综合考虑 2种涂层体系的性能表现及失效机制，在沿海等高腐蚀环境下，应优先选用裸钢-底中面涂层配套体系，以提升防护性能，降低维护成本，保障沿海基础设施的长期稳定运行。

关键词: Q235钢, 镀锌钢, 涂层, 盐雾试验, 紫外老化试验, 失效机制

CLC Number: 

• TQ635. 2