Mg-Zn-Ca表面微弧氧化涂层的制备及耐蚀性能研究  

Study on Preparation and Corrosion Resistance of Micro-arc Oxidation Coating on Mg-Zn-Ca

作　　者：田溪梅 李猛 徐志成 陈民芳[1] 马玉春[1] TIAN Xi-mei;LI Meng;XU Zhi-cheng;CHEN Min-fang;MA Yu-chun(Tianjin University of Technology,Tianjin 300384,China)

机构地区：[1]天津理工大学,天津300384

出　　处：《表面技术》2021年第4期328-334,共7页Surface Technology

基　　金：联合基金项目(U1764254);大学生创新创业训练计划项目(201910060030)。

摘　　要：目的提高Mg-Zn-Ca的耐腐蚀性能。方法在Na_(2)HPO_(4)、NaOH和C3H8O_(3)溶液中,采用微弧氧化(MAO)技术在Mg-Zn-Ca表面通过调节电参数中正向占空比的大小(20%、30%和40%)制备耐蚀性能涂层。利用XRD和SEM表征涂层的物相和形貌。采用光学显微镜测量涂层厚度。采用划痕仪测试涂层与基体的结合力。采用电化学工作站测试涂层的耐腐蚀性能。结果XRD结果表明,涂层物相主要为MgO、Mg_(3)(PO_(4))_(2)、ZnO和Zn_(3)(PO_(4))_(2)。随正向占空比的增加,当2θ角为32.4°、37.2°、43.1°、62.8°时,同一物相对应的衍射峰强度越来越低。SEM结果显示,随正占空比的增加,涂层孔径增大,表面颗粒状涂层产物直径变大。正占空比为20%时,涂层的致密性最好。划痕仪测试结果显示,正占空比为20%时,涂层与基体的结合强度最大,为61.70 MPa。涂层厚度测试表明,正占空比为40%时,涂层最厚,为15.89μm。电化学测试结果表明,正占空比为30%时,涂层的阻抗值最大(490.41Ω),腐蚀电位最高(–1.16 V),腐蚀电流较小(4.9×10–5 A/cm^(2))。Mg-Zn-Ca涂层材料在3.5%的NaCl溶液中的极化形式以电化学极化为主。结论采用微弧氧化方法在Mg-Zn-Ca表面制备了耐蚀涂层,当电参数中正向占空比由20%增加到30%时,涂层的耐蚀性能提高,但占空比继续增大到40%时会导致涂层孔径和孔隙率过大,材料的耐蚀性能反而降低。To improve the corrosion resistance of Mg-Zn-Ca,Micro-arc Oxidation(MAO)technology was used to prepare corrosion-resistant coating on Mg-Zn-Ca by adjusting the positive duty cycle(20%,30%and 40%)in Na_(2)HPO_(4),NaOH and C3H8O_(3) solutions.The phase composition,surface morphology,coating thickness,bonding force and corrosion resistance were characterized by XRD,SEM,optical microscope,scratch tester and electrochemical workstation.XRD results show that the coating phases are mainly MgO,Mg_(3)(PO_(4))_(2),ZnO and Zn_(3)(PO_(4))_(2);the intensity of the diffraction peak of the same object is getting lower and lower with the increasing of positive duty cycle when the 2θangle is 32.4°,37.2°,43.1°and 62.8°;SEM results show that the coating pore size and the diameter of granular coating become larger with the increase of the positive duty cycle,the coating is dense when the positive duty cycle is 20%.The scratch tester results show that the maximum bonding strength is 61.70 MPa when the positive duty cycle is 20%.The coating thickness test results show that the maximum thickness of the coating is 15.89μm when the positive duty cycle is 40%.Electrochemical test results show that the maximum resistance of the coating is 490.41Ω,the largest corrosion potential is–1.16 V and the smaller corrosion current is 4.89×10–5 A/cm^(2) when the positive duty cycle is 30%.The polarization form of the Mg-Zn-Ca in 3.5%NaCl solution is mainly electrochemical polarization.In summary,when the positive duty cycle is increased from 20%to 30%,it can alleviate corrosion resistance,but when the positive duty cycle continues to be increased to 40%,it will lead to excessive coating pore size and porosity,while corrosion resistance of the material is reduced.

关 键 词：Mg-Zn-Ca 耐蚀涂层 制备 性能 微弧氧化 正向占空比 

分 类 号：TG174.4[金属学及工艺—金属表面处理]