Study On Self-crosslinking Acrylic Resin Passivation Film On Aluminum Alloy

Corrosion is a huge problem faced by human beings and environment in today’s society.It is the chemical or electrochemical reaction of metal infiltrated by corrosive medium.Metal corrosion has a great impact on social economy,environmental protection and people’s safety.To protect metal from rapid penetration and corrosion by corrosive medium,barrier layer is usually used to limit or prevent the direct contact between corrosive medium and metal.In recent years,more and more attention has been paid to the environmental-friendly passive coatings.An excellent self-crosslinking cationic acrylate emulsion was prepared by changing the content of cetyltrimethyl ammonium bromide,and polymerizable polyhydroxyamines functional monomer,and using different cross-linking monomers include tripropylene glycol diacrylate(TPGDA),N-hydroxyethyl acrylamide(HEAA)and glycidyl methacrylate(GMA).The self crosslinking acrylic resin passivation film and composite resin passivation film were prepared on ADC12 aluminum alloy plate by using self crosslinking cationic acrylic emulsion as the main film forming material and phytic acid or ammonium hexafluorotitanate inorganic corrosion inhibitors.The acrylic emulsion was characterized by solid content,slagging rate,monomer conversion,emulsion particle size,water absorption,crosslinking degree,infrared spectroscopy(FTIR)and thermogravimetric analysis(DSC).The results showed that the acrylic emulsion prepared with 1.04% content of emulsifier and 10% content of functional monomer had smaller particle size and lower slagging rate.The ratio of2.0%TPGDA,2.0%HEAA and 6.0%GMA increased the crosslinking degree of acrylic emulsion and reduced its water absorption.The corrosion resistance of self crosslinking acrylic resin passivation film and composite resin passivation film were investigated by adhesion test,copper sulfate drop test,neutral salt spray test and electrochemical test.The surface structure of the passivation film was observed by scanning electron microscopy(SEM).The results showed that the self crosslinking acrylic resin passivation film prepared by adding TPGDA crosslinking monomer has poor corrosion resistance,and the self crosslinking acrylic resin passivation film prepared by 2% HEAA and 6% GMA has the best corrosion resistance.And the passivation film prepared with HEAA and GMA as double crosslinking monomers also showed excellent corrosion resistance.The results show that the addition of phytic acid can further improve the corrosion resistance of the passive film,and when the phytic acid content is 1.0%,the corrosion resistance is the best.However,the addition of ammonium fluotitanate can not improve the corrosion resistance of the passive film.The adhesion test results showed that the prepared passivation film has better adhesion with ADC12 Aluminum alloy plate.