Study on the Structure and Corrosion Resistance of Sealing Micro-Arc Oxidation Coatings of Three Types of Siloxanes in Hydrolytic Solutions at Different pH Values

YAN Han, CUI Xuejun, QI Yuming, CENG Shanshan, CHEN Xingyou, REN Qingchuan

doi:10.16577/j.issn.1001-1560.2024.0208

2024 , Vol. 57 >Issue 9: 117 - 124

DOI: https://doi.org/10.16577/j.issn.1001-1560.2024.0208

Study on the Structure and Corrosion Resistance of Sealing Micro-Arc Oxidation Coatings of Three Types of Siloxanes in Hydrolytic Solutions at Different pH Values

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(1.School of Materials Science and Engineering， Sichuan University of Science and Engineering， Zigong 643000， China；2.Sichuan Jiuzhou Elecric Group Co.， Ltd.， Mianyang 621000， China)

CUI Xuejun (1978-)， Professor， Ph.D.， Research Focus: Corrosion/Wear of Metals and New Surface Technologies， E-mail: cxj_2046＠163.com

Received date: 2024-03-12

Revised date: 2024-03-26

Accepted date: 2024-03-27

Online published: 2024-11-14

Supported by

National Natural Science Foundation of China ( 52375196)； Natural Science Foundation of Sichuan Province(2022NSFSC0330)； Graduate Innovation Fund Program of Sichuan University of Science and Engineering (Y2022007)；National Training Program of Innovation and Entrepreneurship(S20221062202)

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Abstract

To further enhance the corrosion protection capability of micro-arc oxidation (MAO) coatings on magnesium alloys， the effects of three different pH values of siloxane hydrolysis solutions on the surface structure and corrosion resistance of MAO/siloxane composite coatings on surface of AZ31B magnesium alloy were investigated.MAO coatings were prepared in a silicate electrolyte system using a constant pressure method.Subsequently， the pH values of the siloxane hydrolysis solutions were adjusted， and siloxane coatings were formed on the MAO coatings by immersion.The micro-morphology，porosity，thickness，roughness，hydrophobicity and corrosion resistance of the coatings were studied using scanning electron microscopy (SEM)， Image-J image analysis， thickness gauge， surface roughness tester， contact angle goniometer and electrochemical workstation.Results showed that compared to micro-arc oxidation coatings， the MAO/siloxane coatings significantly repaired the micropores and defects on the surface of the micro-arc oxidation coatings.The MAO/siloxane coatings also imparted hydrophobic properties， effectively preventing or slowing down the penetration of corrosive media and enhancing the corrosion resistance of the coatings.Among the three siloxanes compared， the composite coating prepared from KH-570 hydrolysate with a pH of 6 exhibited the lowest porosity， a water contact angle of (126.5±2.3)°， and a self-corrosion current density of 3.647×10-8 A/cm2， demonstrating the best corrosion resistance.

Key words： magnesium alloy; micro-arc oxidation; siloxanes; pH values; corrosion resistance

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YAN Han, CUI Xuejun, QI Yuming, CENG Shanshan, CHEN Xingyou, REN Qingchuan . Study on the Structure and Corrosion Resistance of Sealing Micro-Arc Oxidation Coatings of Three Types of Siloxanes in Hydrolytic Solutions at Different pH Values[J]. Materials Protection, 2024 , 57(9) : 117 -124 . DOI: 10.16577/j.issn.1001-1560.2024.0208

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