Enhanced Barrier Of PU Coating By Corrosion Inhibitor Containing Nanocontainer

Corrosion inhibitor containing nanocontainer,as a new coating barrier enhancer,not only achieves the controllable release of corrosion inhibitor,but also endows the coating self-healing ability to some extent.In this thesis,we encapsulated cerium ions in halloysite nanotube to prepare a kind of controlled-release nanocontainer,as well as encapsulated benzotriazole(BTA)in mesoporous silica to prepare another kind of alkaline stimuli-responsive nanocontainer.Eventually,a kind of barrier enhanced Polyurethane(PU)paint was obtained by full dispersion of the nanocontainer in PU slurry.Comprehensive tests were then carried out to investigate the barrier performance of the modified paints.The pore diameter Halloysite nanotubes(HNTs)was firstly increased by etching with HCl,then cerium ions encapsulated HNTs(HNTs+Ce)were formatted by dipping HNTs in Ce(NO3)3 aqueous solution.The terminals of HNTs was finally sealed by using the undissolved complex of Cu(II)ions and benzotriazole,which is supposed to achieve controlled release of filled corrosion inhibitor.The microstructure and chemical compositions were investigated by TEM,XRD and BET tests.In addition,the nanocontainer enhanced PU paint was sprayed on the surface of AA2024 aluminum alloy matrix for the evaluation of their anti-salt spray ability.Neutral salt spray(NSS)and 3.5wt% NaCl immersion tests at 60? indicate that the HNTs+Ce can improved the salt-spray resistance of the PU coating about five times.EIS,AFM also verified that the HNTs+Ce can control the release of inhibitive cerium ion by the stimulation of immigrating water,which therefore improve the barrier performance of PU coatings.Moreover,mesoporous silica(MSN)was prepared by traditional template method,then the mesopores soaked with BTA inhibitor and sealed by CB[6].Then,the surface of MSN was modified by silane coupling agent and butanediamine sequentially to prepare alkaline stimuli-responsive MSN nanocontainer.PU paint doped with the BTA-MSN nanoparticles was firstly sprayed on AA2024 aluminum alloy,and then subjected to the NSS and 3.5wt% NaCl immersion tests at 60?,the UV absorbency test indicated that BTA was released from the BTA-MSN nanocontainer spontaneously in alkaline solution.EIS suggested that the BTA-MSN nanoparticles could improve the anti-salt spray ability of PU coating about six times.The release curves of cerium ion and BTA,which have been encapsulated in nanocontainers,showed that both HNTs and MSN could achieve promising controlled release of corrosion inhibitors.Especially,the BTA-MSN nanocontainer exhibits a quick respond to the pH change of solution.In other words,the alkaline environment of PU /Al interface can promotes the BTA release.This controlled release policy not only promotes the corrosion resistance and prolongs the durability of coating efficiently,also it endows the PU coating self-healing capability to some degree.