Anticorrosive Property Of Self-healing Epoxy Coatings Based On Mesoporous Materials

2024-T3 aluminum alloy is widely used in aircraft industry due to their light mass and excellent properties.Elements,such as Cu,Mg,Fe and Mn,are often introduced in the alloy so as to improve the strength of the alloy.However,these additive elements decrease the corrosion resistance of the alloy at the same time.In order to improve the corrosion resistance,chromate conversion coating and primer has been applied for the corrosion protection of the alloy for very long time.However,due to the toxicity and carcinogenicity,chromates are progressively limited and banned to be used.Thus,the development of novel coatings to replace chromate coating has become a focus for researchers.It has been found that the self-healing coatings are viable methods to replace chromate coatings to corrosion protection.This thesis also studies the novel self-healing epoxy coating for protection of 2024-T3 alumnium alloy from the concept of self-healing coating.Firstly,mesoporous silica MSO-150 is selected as nanocontainers.The nanocontainer were loaded with inhibitor(8-HQ)and release of the inhibitor was controlled by the formationof PEI/PSS over the outer sueface.FTIR,SEM,TEM,UV-2100 spectrophotometer,EIS and polarization tests were used to verify the effect of the coatingand investigate the effect of corrosion inhibitor that releases from mesoporous silica MSO-150.The results show that the structure of ordered mesoporous structure in MSO-150 becomes disorderly afterloaded with 8-HQ.The loaded content of 8-HQ for is 80 mg/g.It was found that the release of the inhibitor in mesoporous MSO-150 is affected by pH.The release rate of 8-HQ is slow when pH is in the neutral range and is fast when pH is in the acidic and alkaline range.At the same time,the released 8-HQ from MSO-150 can improve the corrosion resistance of 2024-T3 aluminum alloy.Secondly,MSO-150 was modified by silane coupling agent KH-X1.FTIR,SEM,TEM and UV VIS spectrophotometer,EIS and polarization tests were also used to study the structure of mesoporous MSO-150 containing corrosion inhibitors and the effect of corrosion protection on the aluminum alloy.The results show that the hydrophobicity is enhanced and the loaded content of 8-HQ is therefore increased after surfacemodified by silane.At last,the two kinds of MSO-150 containing 8-HQ were doped into an epoxy coating.The corrosion resistance of the epoxy coatings were studied by salt spray test,immersion test and electrochemical impedance spectroscopy(EIS).The results show that the doping of mesoporous MSO-150 containing 8-HQ increases the value of modulus value of the epoxy coating by three orders of magnitude.The self-healing coatings have excellent cossosion resistance.