Evaluation Method Research For Coating Protection Performance On The Basis Of Accelerated Corrosion And EIS In A Short Time

In this paper, we have taken testing and evaluation research on the basis of accelerated corrosion and electrochemical testing with hot-dip galvanizing(HDG), sherardizing, epoxy primer/chlorinated rubber, epoxy primer/epoxy micaceous iron oxide/acrylic urethane and epoxy zinc-rich primer/epoxy micaceous iron oxide/acrylic urethane coatings for the study.The results were shown as follows:(1) The corrosion rate of hot-dip galvanizing and sherardizing is lower than Q235 carbon steel. The corrosion resistance of hot-dip galvanizing and sherardizing is wonderful for Q235 carbon steel. In addition, the corrosion rate of hot-dip galvanizing is lower than sherardizing, the corrosion resistance of sherardizing is better.(2) The gray correlation of test results for atmospheric corrosion test in chemical atmospheric environment and accelerated test indoor are more than 0.6. The accelerated test indoor is not only has remarkable acceleration effect, but also correlated with atmospheric corrosion test in chemical atmospheric environment. It can be used to evaluate the corrosion resistance of metal coating that is sacrificial anode. The results of accelerated test indoor can be used for life prediction.(3) The tendency of characteristic parameters as low-frequency impedance value, coating resistance, high frequency capacitance, the characteristic frequency is shown in electrochemical impedance spectroscopy(EIS). So we can speculate coating/metal interface structure and coatings anti-penetration by electrochemical impedance spectroscopy, and then evaluate coatings protection performance.(4) After testing 270 days in Wuhan urban atmospheric environment and chemical atmospheric environment, the loss rate of coating surface gloss is less than 0.2. The protection performance of epoxy primer/chlorinated rubber, epoxy primer/epoxy micaceous iron oxide/acrylic urethane and epoxy zinc-rich primer/epoxy micaceous iron oxide/acrylic urethane coatings is well. However, the loss rate of coating surface gloss in chemical atmospheric environment is more than it in Wuhan urban atmospheric environment. Chemical atmospheric environment is harsher. The loss rate of coating surface gloss with accelerated test after 960, 1920 and 2880 hours and atmospheric corrosion test after 90, 180 and 270 days is similar. So accelerated test and atmospheric corrosion test is relational.(5) The low-frequency impedance value for coating after 180 days in Wuhan urban atmospheric environment is related to it for coating after 960 hours in accelerated test. The low-frequency impedance value for coating after 180 days in chemical atmospheric environment is related to it for coating after 1920 hours in accelerated test. They all have the same magnitude. In addition, the low-frequency impedance value for coating after 270 days in Wuhan urban atmospheric environment is related to it for coating after 1920 hours in accelerated test, the low-frequency impedance value for coating after 270 days in chemical atmospheric environment is related to it for coating after 2880 hours in accelerated test. They also have the same magnitude. Accelerated test and atmospheric corrosion test is relational with low-frequency impedance value. So we can evaluate coatings protection performance with Accelerated test indoor and low-frequency impedance value for coatings.