Effect of Silanization on Degradation Performance of Micro-arc Oxidation Coatings on Magnesium Alloys Surfaces

doi:10.12068/j.issn.1005-3026.2025.20250013

Abstract

Abstract:

Three types of processes， including electrodeposition， vacuum impregnation， and conventional immersion， were used to modify the micro-arc oxidation （MAO） coatings on Mg-0.45Zn-0.45Ca alloys using KH550 silane.The effects of these silanization processes on the sealing effect for the defects within the MAO coating on the surface of medical magnesium alloys and the long-term degradation performance of the coating in simulated body fluid （SBF） were studied by scanning electron microscopy， Vickers hardness tester， and electrochemical measurements.The results show that silane films can be successfully prepared on the surface of the MAO coating using these three types of processes.Among them， the silane film with a thickness of 1.5~7 μm can be fabricated by electrodeposition， which shows a superior sealing effect to the MAO coating and can enhance the hardness and adhesion strength of the coating.Besides， the MAO coating prepared by electrodeposition after immersion for three months in SBF can effectively protect the magnesium substrate， satisfying the requirements for the biodegradable biomedical magnesium alloys.Therefore， the Mg-0.45Zn-0.45Ca alloy with KH550 silanization electrodeposition and MAO has the potential to be used as degradable magnesium alloys implants.

Key words: magnesium alloy, coating, silane, electrodeposition, long-term degradation performance

CLC Number:

TG 17

Tao ZHANG, Chuang LIU, Yi ZHANG, Fu-hui WANG. Effect of Silanization on Degradation Performance of Micro-arc Oxidation Coatings on Magnesium Alloys Surfaces[J]. Journal of Northeastern University(Natural Science), 2025, 46(8): 105-112.

Figures/Tables 10

Table 1 Compositions of Mg-0.45Ca-0.45Zn alloys

Mn	Cu	Zn	Si	Ca	Al	Fe	Mg
0.036	0.000 4	0.60	0.037	0.31	0.026	0.003	余量

Fig.1 SEM images of PEO coating and PEO/KH550 composite coatings prepared by different processes

Fig.2 FTIR spectrum of PEO/KH550 composite coatings prepared by different processes

Fig.3 Vickers hardness and adhesion of PEO coating and PEO/KH550 composite coatings prepared by different processes

Fig.4 Polarization curves of PEO coating and PEO/KH550 composite coatings prepared by different processes

Table 3 Fitting results of potentiodynamic

样品	i_corr/(µA·cm^-2)	E_corr/V	E_b/V
PEO	0.029	-1.91	-1.62
PEO/KH550 常规浸渍	0.028	-1.74	-1.32
PEO/KH550电沉积	0.002	-1.78	-1.21
PEO/KH550 真空浸渍	0.062	-1.79	-1.34

Fig.5 Impedance spectrum of PEO coating and PEO/KH550 composite coatings prepared by different processes after immersion in SBF for different days

Fig.6 Equivalent circuits of electrochemical impedance spectrum

Fig.7 Relationship between degradation rate and immersion time

Fig.8 Morphology of PEO coating and PEO/KH550 composite coatings prepared by different processes after immersion in SBF for different days

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