摘要
目的进一步提高ZM5镁合金微弧氧化(MAO)涂层的耐磨和耐蚀性能。方法在镁合金表面制备了不含与含有SiC和CeO_(2)纳米颗粒的3种MAO涂层。使用扫描电子显微镜(SEM)、能量色散X射线光谱仪(EDS)和X射线衍射仪(XRD),对MAO涂层的表面形貌和成分结构进行分析,通过摩擦试验测试了涂层的耐磨性能,通过极化曲线(Tafel)和电化学阻抗谱(EIS)测试了涂层的耐蚀性能。结果含有SiC纳米颗粒的MAO涂层厚度、硬度分别提升了19.40%、86.56%,含有CeO_(2)纳米颗粒的MAO涂层厚度、硬度分别提升了3.74%、44.59%。含有SiC纳米颗粒的涂层孔隙率升高6.60%,而添加CeO_(2)使涂层的孔隙率下降23.90%。摩擦试验表明,不含纳米颗粒的MAO涂层磨痕深度为36.4µm,而含有纳米颗粒的涂层磨痕深度可以忽略不计。Tafel试验表明,CeO_(2)纳米颗粒可以显著降低MAO涂层的腐蚀电流密度,从1.41×10^(‒9) A/cm^(2)降至5.72×10^(-10) A/cm^(2)。同时延长了涂层的稳定钝化区间180 mV。EIS试验也表明,浸泡前后,含有CeO_(2)纳米颗粒的涂层都具有最高的低频阻抗值。结论纳米颗粒可以填充MAO涂层中的孔隙和裂纹,增大涂层的厚度和硬度,因此有效地改善涂层的耐磨性能。但在MAO处理时,SiC纳米颗粒增大了涂层的稳定电流密度,提高了等离子体放电强度,导致纳米颗粒的填充作用不明显,使涂层孔隙率升高。同时,含有CeO_(2)纳米颗粒的涂层具有较小的孔隙率,并且厚度较大。因此CeO_(2)纳米颗粒还可以有效地改善涂层的耐蚀性能。
Micro-arc oxidation(MAO)is an advanced surface modification technology,which can improve material properties,such as corrosion resistance and wear resistance.To further improve the wear and corrosion resistance of the MAO coatings on ZM5 magnesium(Mg)alloy,the MAO coatings with different nanoparticles(no,SiC and CeO_(2))were prepared on the ZM5 Mg alloy.ZM5 Mg alloy samples were cut in the size of 20 mm×20 mm×5 mm.Prior to the MAO process,the substrate was polished with silicon carbide paper in 320 grit.Then the samples were cleaned with deionized water,anhydrous ethanol and dried immediately.The working size of the sample was 20 mm×20 mm,and the other parts were coated with silicone.The power supply(PN-III power source)was used to prepare MAO coating under a constant voltage mode(400±5)V for 20 min.The pulse frequency was 1000 Hz and the duty ratio was 40%.The electrolyte solution was 2 g/L sodium hydroxide(NaOH),15 g/L sodium silicate(Na2SiO_(3)),and 5 g/L sodium fluoride(NaF).The MAO coatings with different nanoparticles were prepared by adding 5 g/L SiC nanoparticles or 5 g/L CeO_(2) nanoparticles to the electrolyte.During the MAO treatment,the electrolyte temperature was maintained at(30±5)℃through the cooling system.After the treatment,the surfaces of the samples were sequentially rinsed with distilled water,anhydrous ethanol and then dried by cool airflow immediately.The surface morphology of MAO coatings was analyzed by SEM(Phenom XL).The composition was analyzed by EDS and XRD(Ultima Ⅳ).The wear resistance was studied by friction tests(rTEC MFT 5000).And the corrosion resistance was tested by Tafel and EIS(CHI-604C).The thickness of MAO coatings with SiC and CeO_(2) nanoparticles increased by 19.40%and 3.74%,respectively.And the microhardness of MAO coatings with SiC and CeO_(2) nanoparticles increased by 86.56%and 44.59%,respectively.The porosity of MAO coatings with SiC nanoparticles increased by 6.60%but with CeO_(2) nanoparticles decreased by 23.90%.The result of the friction tests showed that the MAO coatings without nanoparticles had an abrasion depth of 36.4µm,while the MAO coatings with SiC and CeO_(2) nanoparticles had a negligible abrasion depth.The result of Tafel showed that the corrosion current density of MAO coatings with CeO_(2) nanoparticles significantly reduced from 1.41×10^(‒9) A/cm^(2) to 5.72×10^(-10) A/cm^(2) and the passivation zone extended by 180 mV.The result of EIS also showed that the coatings with CeO_(2) nanoparticles had the highest impedance value at low frequency in immersion.During the MAO treatment,the nanoparticles can fill the pores and cracks in the MAO coatings and enhance the growth rate of the MAO coating,resulting in an increase in the thickness and microhardness of the coatings.Thus,SiC and CeO_(2) nanoparticles improved the wear resistance of the MAO coating.During the MAO process,the SiC nanoparticles increased the stable current density,resulting in insignificant filling of the nanoparticles.Therefore,the SiC nanoparticles increased the porosity of the coatings.In contrast,CeO_(2) nanoparticles reduced the porosity.Thus,CeO_(2) nanoparticles improved the corrosion resistance of the MAO coating.
作者
李健鹏
万红霞
涂小慧
李卫
郭静
宋东东
LI Jian-peng;WAN Hong-xia;TU Xiao-hui;LI Wei;GUO Jing;SONG Dong-dong(Institute of Advanced Wear&Corrosion Resistant and Functional Materials,Jinan University,Guangzhou 510632,China;Department of Materials Science and Engineering,China University of Petroleum,Beijing,Beijing 102249,China;China Special Equipment Inspectionand Research Institute,Beijing 101300,China;Key Laboratory of Energy Transfer and System of Power Station of Ministry of Education,North China Electric Power University,Beijing 102206,China)
出处
《表面技术》
EI
CAS
CSCD
北大核心
2022年第12期131-141,共11页
Surface Technology
基金
国家自然科学基金(51701055)
国家市场监督管理总局科技计划项目(2019MK134)。
作者简介
李健鹏(1997-),男,硕士研究生,主要研究方向为材料腐蚀与防护;通讯作者:万红霞(1986-),女,博士,讲师,主要研究方向为石油管道腐蚀与防护。
