自交联阳离子丙烯酸乳液对ADC12铝合金的钝化研究

Study on Passivation of ADC12 Aluminum Alloy by Self-crosslinking Cationic Acrylic Emulsion

目的制备自交联阳离子丙烯酸乳液,提高ADC12铝合金表面树脂钝化膜的耐蚀性能。方法丙烯酸丁酯(BA)和甲基丙烯酸甲酯(MMA)为单体,可聚合多羟基有机胺为功能单体,N-羟乙基丙烯酰胺(HEAA)为交联剂单体,使用半连续乳液聚合法制备自交联阳离子型聚丙烯酸酯乳液,并采用浸渍法在ADC12铝合金板上制备钝化膜。通过激光纳米粒度仪和示差扫描量热分析仪(DSC)对乳液进行表征。采用电化学Tafel极化曲线、交流阻抗(EIS)、硫酸铜点滴试验及中性盐雾试验,对比分析添加交联单体前后树脂钝化膜的耐腐蚀性能。结果添加HEAA为交联单体制备自交联阳离子聚丙烯酸酯乳液,乳液平均粒径为88~96 nm,粒径分布均匀,并明显提高了聚丙烯酸酯乳液树脂的玻璃化温度。HEAA含量为2%时,乳液平均粒径为88 nm,粒径分布均匀,玻璃化温度提高了18.8℃,且钝化膜24 h中性盐雾试验后基本无腐蚀,腐蚀电流密度为2.609×10^(−7)A/cm^(2),腐蚀电位为−0.592 V,耐硫酸铜腐蚀时间为53 s。结论交联单体HEAA的添加能够有效提高树脂钝化膜的交联密度,阻碍腐蚀介质的侵入,提高树脂钝化膜的耐腐蚀性能。

The work aims to prepare self-crosslinking cationic acrylic emulsion to improve the corrosion resistance of the resin on the ADC12 aluminum alloy surface.Taking butyl acrylate(BA)and methyl methacrylate(MMA)as monomers,polymerizable polyhydroxy organic amine as a functional monomer,and N-hydroxyethyl acrylamide(HEAA)as a crosslinking agent monomer,the self-crosslinking cationic acrylic emulsion was prepared by semi-continuous emulsion polymerization.The passive film was prepared on ADC12 aluminum alloy plate by dipping method.The emulsion were characterized by laser nanoparticle sizer and differential scanning calorimetry(DSC).Tafel polarization curve measurement,AC impedance spectroscopy(EIS),copper sulfate drop corrosion test and neutral salt spray test were used to compare and analyze the corrosion resistance of the resin passivating film with or without crosslinking monomer.The average particle sizes of self-crosslinking cationic acrylic emulsion with HEAA as the crosslinking monomer were 88~96 nm and the particle size distribution were uniform.The glass transition temperature of the acrylic emulsion resin were also significantly increased.When the HEAA content is 2%,the average particle size of the emulsion is 88 nm,the particle size distribution is uniform,the glass transition temperature is increased by 18.8℃,and the passivating film has no corrosion after 24 h neutral salt spray test,the corrosion current density is 2.609×10^(−7)A/cm^(2),the corrosion potential is−0.592 V,and the corrosion resistance time of copper sulfate is 53 s.The addition of the crosslinking monomer HEAA can effectively increase the crosslinking density of the resin passivating film,hinder the intrusion of corrosive media,and improve the corrosion resistance of the resin passivating film.