Study on corrosion resistance of passive film promoted by natural rosin-based passive sealant

An eco-friendly Rosin-based passive sealant is prepared, which can seal the micropores and repair the passive film in one-step. Sealing performance of sealants and the growth kinetics of the passive film were analyzed by 3D-XRT tomography, Electrochemistry and XPS. The results showed that the permeation depth of sealant reached more than 150 μm, and the natural rosin effectively prolonged the loss time of sealant. The phosphate conversion layer at the passive film/sealant interface changes the semiconductor properties of the passive film. After immersion for 360 h in 3.5 wt% NaCl solution, the amount of Fe2O3 and Cr2O3 in the passive film increased by 34 % and 20 %, respectively, and the film thickness increased by 257.9 %. Rosin-based passive sealant can directly inhibit the diffusion rate of defects in passive film. This study provides a new theoretical support for the application of rosin sealant.