Study on Microstructures and Corrosion Resistance of SPS Al-Al2O3 Composite Coatings on Magnesium Alloy Substrate

被引：0
作者：
Ren, Dongting [1 ,2 ]
Wang, Wenquan [1 ]
Zhang, Xin'ge [1 ]
Du, Wenbo [3 ]
Zhu, Sheng [3 ]
机构：
[1] Key Laboratory of Automobile Materials of Ministry of Education, School of Materials Science and Engineering, Jilin University, Changchun
[2] China Institute for Radiation Protection, Taiyuan
[3] National Key Laboratory for Remanufacturing, Army Academy of Armored Forces of PLA, Beijing
来源：
Cailiao Daobao/Materials Reports | 2024年 / 38卷 / 16期
关键词：
Al-Al[!sub]2[!/sub]O[!sub]3[!/sub] composite coating; corrosion resistance; magnesium alloy; porosity; supersonic plasma spray(SPS);
D O I：
10.11896/cldb.22120140
中图分类号：
学科分类号：
摘要：
Magnesium alloy corrosion resistance is poor,in engineering applications often due to corrosion and failure,through surface engineering technology to magnesium alloy surface modification or protection,is an important means used in engineering applications. In this work,the supersonic plasma spray (SPS)process was used to prepare Al-Al2 O3 composite coating on the surface of AZ61 magnesium alloy,in which the mass fractions of Al2 O3 were 30%,50% and 70% (hereinafter referred to as AA30,AA50 and AA70),and the effects of Al2 O3 content on the microstructure,porosity,electrochemical properties and corrosion resistance of Al-Al2 O3 composite coatings were studied. The results show that the surface of the coating presents a wave-like morphology formed by the spread and stacking of molten droplets,the powder is fully melted,and the internal bonding of the coating is tight. And the coating was composed of Al,α-Al2 O3 and γ-Al2 O3 phases. The porosity of AA70 coating was significantly higher than that of AA30 and AA50,reaching 6. 71%. In the electrochemical polarization test,each coating showed higher electrode potential and lower self-corrosion current density than that of AZ61 magnesium alloy. The test revealed that AZ61 self-corrosion current density was 5. 144 mA·cm-2,while AA30,AA50 and AA70 self-corrosion current densities were 2. 950 mA·cm-2,3. 084 mA·cm-2 and 2. 496 mA·cm-2, respectively. The coatings of AA30,AA50 and AA70 showed a lower corrosion rate than that of the base metal AZ61. The electrochemical impedance test results showed that the Rct of the three coatings reached about twice that of the AZ61 magnesium alloy matrix,showing lower anodic solubilization activity. In the salt spray test,a large number of corrosion products and cracks are produced on the surface of AZ61 magnesium alloy. Coatings AA30 and AA50 have a large number of cracks in the coating due to the accumulation of corrosion products,and galvanic corrosion occurs at the interface between the coating and the substrate. Eventually,as the surface of the substrate corrodes,the coating peels off. The coating AA70 has minimal corrosion rate and provides optimum corrosion resistance for long-term protection of the substrate. © 2024 Cailiao Daobaoshe/ Materials Review. All rights reserved.
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