This paper describes the use of innovative, nanosilica containing epoxy powder coatings for the corrosion protection of steel. Two types of nanosilica particles (hydrophilic -HL- and hydrophobic -HB-) were mixed by ball milling with the powders (0.75 wt.%). The adequate homogeneity and embedding of nanoparticles were verified by transmission electron microscopy. The corrosion performance of the coatings as-received, and with HL and HB additions, were analyzed in 3.5 wt.% NaCl solutions. The mechanism and rate of delamination of defective coatings under drops simulating atmospheric conditions were analyzed by Scanning Kelvin Probe measurements for 30 d. The results show that the corrosion attack progresses through a cathodic delamination mechanism. Besides, fully-immersed samples, with and without defects, were monitored by electrochemical impedance spectroscopy. In defective coatings under these conditions, the occurrence of anodic undermining is proved. The results obtained reveal that the corrosion driven coating failure is delayed in the case of the epoxy coatings containing nanosilica. This delay is larger in the case of HB additions than HL additions in both atmospheric and immersion conditions. The corrosion mechanism observed is dependent upon exposure conditions. It is proposed that the nanoparticles delay water absorption, thus delaying corrosion attack.

本文介绍了如何使用创新的含纳米二氧化硅的环氧粉末涂料对钢进行腐蚀防护。通过球磨将两种类型的纳米二氧化硅颗粒（亲水性-HL-和疏水性-HB-）与粉末（0.75 wt。％）混合。通过透射电子显微镜证实纳米颗粒具有足够的均匀性和包埋性。在3.5重量％的NaCl溶液中分析了所接收的涂层以及添加HL和HB后的涂层的腐蚀性能。通过扫描开尔文探针测量30 d分析了在模拟大气条件的液滴下缺陷涂层的剥离机理和脱层速率。结果表明，腐蚀攻击是通过阴极分层机制进行的。此外，完全浸没的样品，有无瑕疵，通过电化学阻抗谱监测。在这些条件下的缺陷涂层中，证实了阳极破坏的发生。获得的结果表明，在包含纳米二氧化硅的环氧涂层的情况下，腐蚀驱动的涂层失效被延迟。在大气和浸没条件下，添加HB的延迟要比添加HL的延迟大。观察到的腐蚀机理取决于暴露条件。提出了纳米颗粒延迟水吸收，从而延迟腐蚀攻击。在大气和浸没条件下，添加HB的延迟要比添加HL的延迟大。观察到的腐蚀机理取决于暴露条件。提出了纳米颗粒延迟水吸收，从而延迟腐蚀攻击。在大气和浸没条件下，添加HB的延迟要比添加HL的延迟大。观察到的腐蚀机理取决于暴露条件。提出了纳米颗粒延迟水吸收，从而延迟腐蚀攻击。