| LI Jian-peng,WAN Hong-xia,TU Xiao-hui,LI Wei,GUO Jing,SONG Dong-dong.Effect of Nanoparticles on the Wear and Corrosion Resistance of MAO Coatings on ZM5 Mg Alloy[J],51(12):131-141 |
| Effect of Nanoparticles on the Wear and Corrosion Resistance of MAO Coatings on ZM5 Mg Alloy |
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| DOI：10.16490/j.cnki.issn.1001-3660.2022.12.013 |
| KeyWord:ZM5 magnesium alloy MAO coating nanoparticles wear resistance corrosion resistance |
| Author | Institution |
| LI Jian-peng |
Institute of Advanced Wear & Corrosion Resistant and Functional Materials, Jinan University, Guangzhou , China |
| WAN Hong-xia |
Department of Materials Science and Engineering, China University of Petroleum, Beijing, Beijing , China |
| TU Xiao-hui |
Institute of Advanced Wear & Corrosion Resistant and Functional Materials, Jinan University, Guangzhou , China |
| LI Wei |
Institute of Advanced Wear & Corrosion Resistant and Functional Materials, Jinan University, Guangzhou , China |
| GUO Jing |
China Special Equipment Inspectionand Research Institute, Beijing , China |
| SONG Dong-dong |
Key Laboratory of Energy Transfer and System of Power Station of Ministry of Education, North China Electric Power University, Beijing , China |
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| Abstract: |
| 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 CeO2) 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 1 000 Hz and the duty ratio was 40%. The electrolyte solution was 2 g/L sodium hydroxide (NaOH), 15 g/L sodium silicate (Na2SiO3), 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 CeO2 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 CeO2 nanoparticles increased by 19.40% and 3.74%, respectively. And the microhardness of MAO coatings with SiC and CeO2 nanoparticles increased by 86.56% and 44.59%, respectively. The porosity of MAO coatings with SiC nanoparticles increased by 6.60% but with CeO2 nanoparticles decreased by 23.90%. The result of the friction tests showed that the MAO coatings without nanoparticles had an abrasion depth of 36.4 µm, while the MAO coatings with SiC and CeO2 nanoparticles had a negligible abrasion depth. The result of Tafel showed that the corrosion current density of MAO coatings with CeO2 nanoparticles significantly reduced from 1.41×10‒9 A/cm2 to 5.72×10‒10 A/cm2 and the passivation zone extended by 180 mV. The result of EIS also showed that the coatings with CeO2 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 CeO2 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, CeO2 nanoparticles reduced the porosity. Thus, CeO2 nanoparticles improved the corrosion resistance of the MAO coating. |
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