Preparation And Failure Mechanism Of Superhydrophobic And Self-healing Double-effect Intelligent Coating

Intelligent coating has attracted the attention of many researchers because of its biological characteristics such as self-healing,self-cleaning,self-lubricating and antibacterial.At present,researchers mainly focus on the study of single-function intelligent coating,but there are only a few reports on the preparation of multi-function intelligent coating,and lack of research on its service performance.Therefore,it is of great theoretical and practical value to develop multifunctional intelligent coating and find out its failure mechanism.In this paper,lignocellulose nanofiber(CNF)was used to load polyaspartic acid(PASP)and then introduced into epoxy resin coating to obtain self-healing intelligent coating.Nano-composite epoxy resin was sprayed on the outermost layer of self-healing coating by two-layer design to obtain super hydrophobic-self-healing intelligent coating.The self-healing and service performance of the coating were studied by electrochemical test,multi-factor coupling corrosion simulation test,scanning electron microscope and atomic force microscope,and finally the failure mechanism of the coating was discussed.The specific research results are as follows:(1)After being corroded by 3.5 wt.%Na Cl solution for 24 h,the low-frequency impedance value of the self-healing coating of 1%CNF+4%PASP is nearly 1 order of magnitude higher than that of the blank coating,and its electrochemical noise resistance increases from 2421?·cm² to 10780?·cm² in the simulated multi-factor coupled marine atmosphere,which has excellent self-healing effect.(2)The Si O₂ particles were modified by perfluorodecyl trimethoxysilane and mixed with bisphenol epoxy resin modified by 3-glycidyl ether oxypropyl trimethoxysilane at a ratio of 10:4.The coating was super hydrophobic,and its hardness was 6 H,which reached the use standard of metallic paint(Hardness?3 H).Using the two-layer design,the above coating was sprayed on the outermost layer of the self-healing coating,and finally the superhydrophobic and self-healing double-effect intelligent coating was prepared.(3)After 35 days simulated marine atmospheric corrosion experiment,the relationship between corrosion degree of carbon steel samples:blank coating>self-healing coating>superhydrophobic and self-healing coating.Compared with blank coating,the self-healing coating can inhibit the penetration of corrosive medium,while the superhydrophobic and self-healing double-effect coating will play a strong role in blocking the corrosive medium based on the self-healing coating.(4)The failure mechanism of the coating in simulated marine atmospheric environment includes two aspects:on the one hand,the C-O and C-H molecular chains in the coating break due to absorption of UVA energy,resulting in chemical degradation;On the other hand,due to water absorption in the coating under wet conditions,the corrosive medium penetrates into the coating,resulting in physical failure.