CAJ | 학술논문

由于结构和成分的影响,覆有微弧氧化涂层的AZ91D镁合金的极化曲线有多种不同的表现形式.事实上,覆有微弧氧化涂层的AZ91D镁合金在NaCl溶液中的极化曲线行为不仅与涂层的主要组成和微观结构有关,也与极化曲线测试条件,如氯离子浓度、溶液pH值、阴极极化程度和样品的暴露面积有关,由于微弧氧化涂层的不稳定性,这些因素通过改变氧化涂层的组成和微观结构,继而影响极化曲线的形状.本文用傅里叶变换显微红外成像和对应的光学照片研究了氧化涂层的成分和结构的变化.结合物理表征,我们提出一个模型,用以阐明微弧氧化涂层组成和结构在NaCl溶液中的变化.对于浸泡在NaCl溶液中的AZ91D微弧氧化涂层,阳极溶解和阴极还原反应的速控步骤分别是传质过程和电荷转移过程.所以从极化曲线上拟合出来的腐蚀电流密度不能准确反映腐蚀速率,而且误差也难以避免.
유우결구화성분적영향,복유미호양화도층적AZ91D미합금적겁화곡선유다충불동적표현형식.사실상,복유미호양화도층적AZ91D미합금재NaCl용액중적겁화곡선행위불부여도층적주요조성화미관결구유관,야여겁화곡선측시조건,여록리자농도、용액pH치、음겁겁화정도화양품적폭로면적유관,유우미호양화도층적불은정성,저사인소통과개변양화도층적조성화미관결구,계이영향겁화곡선적형상.본문용부리협변환현미홍외성상화대응적광학조편연구료양화도층적성분화결구적변화.결합물리표정,아문제출일개모형,용이천명미호양화도층조성화결구재NaCl용액중적변화.대우침포재NaCl용액중적AZ91D미호양화도층,양겁용해화음겁환원반응적속공보취분별시전질과정화전하전이과정.소이종겁화곡선상의합출래적부식전류밀도불능준학반영부식속솔,이차오차야난이피면.
The polarization curves of magnesium alloy AZ91D with a micro-arc oxidation (MAO) coating showed several typical patterns caused by differences in the composition and structure of the coating.The pattern of the polarization curve of magnesium alloy AZ91D with a MAO coating depends on the primary composition and structure of the MAO coating and many experimental factors,such as the concentration of chloride ions,pH of the electrolyte,degree of cathodic polarization,and the exposed area of the specimen.These factors change the pattern of polarization curve of magnesium alloy AZ91D with MAO coating by affecting the main composition and structure of the MAO coating because of its instability in aqueous solution.Compositional and structural changes in the MAO coating on magnesium alloy AZ91D were investigated by Fourier transform infrared microscopic mapping and the corresponding optical photographs,respectively.A model was proposed to describe the transformation of the MAO coating in aqueous NaCl solution.For magnesium alloy AZ91D with a MAO coating immersed in NaCl solution,the rate determining steps of the anodic and cathodic reactions are the mass diffusion and charge transfer steps,respectively.As a result,the corrosion current density fitted from the polarization curve is not an accurate corrosion rate.