用电化学方法研究火焰喷涂乙烯丙烯酸共聚物涂层的防腐蚀性能

Corrosion Resistance of Flame Sprayed Coating of Ethylene Acrylic Acid Copolymer

为了研究乙烯丙烯酸共聚物(EAA)涂层的防腐蚀性能,采用火焰喷涂技术制备了EAA涂层,利用傅里叶变换红外光谱(FTIR)研究了火焰喷涂对EAA涂层结构的影响;用扫描电镜(SEM)和拉伸强度试验研究了EAA涂层的形貌及力学性能;利用交流阻抗(EIS)和Tafel曲线研究了EAA涂层在3.5%NaCl溶液中的防腐蚀性能,初步探讨了其机理。结果表明:EAA涂层结构密实,与基体结合良好,其在3.5%NaCl溶液中浸泡初期能起到良好的腐蚀屏蔽作用,随着浸泡时间的延长,腐蚀介质通过涂层的通孔、微裂纹等缺陷渗入涂层与基体的界面腐蚀基体,使涂层电阻Rc下降、电容Cc增加、腐蚀电位Ecorr负移、腐蚀电流密度Jcorr增加,涂层防腐蚀性能减弱。

Coating of ethylene-acrylic acid copolymer(EAA) was prepared by flame spraying.The effect of flame spraying on the chemical structure of EAA coating was investigated by Fourier transform infrared spectrometry.The morphology of as-sprayed EAA coating was observed using a scanning electron microscope,and its mechanical properties were examined using a tensile strength meter.In the meantime,the corrosion resistance of the EAA coating in aqueous solution of 3.5% NaCl was evaluated by measuring the electrochemical impedance spectra and Tafel curves,and its anticorrosion mechanism was primarily discussed.It was found that as-sprayed EAA coating was dense and well combined with the substrate,showing good anticorrosion ability during the early stage of immersion in the saline water.However,at an extended immersion duration,the corrosive medium was able to penetrate into the coating-substrate interface via defects such as through-holes and micro-cracks,causing reduction of resistance,increase of capacity,negative shift of corrosion potential,and increase of corrosion current density of the coating.As a result,the anticorrosion ability of the coating was decreased.