Role of Sodium Silicate for Coating Forming on Magnesium Alloys with Micro Arc Oxidation

doi:10.13373/j.cnki.cjrm.XY18090038

	Role of Sodium Silicate for Coating Forming on Magnesium Alloys with Micro Arc Oxidation
	Sun, Le; Ma, Ying; Dong, Hairong; An, Lingyun; Wang, Sheng
刊名	Xiyou Jinshu/Chinese Journal of Rare Metals
	2020-04-01
卷号	44 期号:4 页码:378-386
关键词	Corrosion resistance Electrolytes Magnesium alloys Magnesium compounds Scanning electron microscopy Silicates Sodium compounds Sodium silicate process AZ91D magnesium alloys Corrosion current densities Ignition voltage Linear polarization resistance Microarc oxidation Solution conductivity Specimen surfaces Thermal accumulation
ISSN号	02587076
DOI	10.13373/j.cnki.cjrm.XY18090038
英文摘要	AZ91D magnesium alloys were processed by micro arc oxidation (MAO) in electrolytes without and with sodium silicate, respectively. The role of sodium silicate during MAO treatment was investigated and its effect on MAO coatings was analyzed. Scanning electron microscope (SEM) and X-ray diffraction (XRD) were employed to characterize the microstructure and phase composition of MAO coatings, respectively. And the corrosion resistance of MAO coatings was evaluated by electrochemical workstation. The results showed that a complete, uniform coating was obtained during MAO treatment once sodium silicate was added into the electrolyte, and in turn, the coating's compactness was improved and a new phase Mg2SiO4 with excellent properties was generated in the coatings. With addition of sodium silicate into the electrolyte, the solution conductivity increased and the ignition voltage on specimen surfaces decreased during MAO process, which facilitated a breakdown easily developing on specimen surfaces. Further on this foundation, the competing state in terms of the potential levels in different areas would be enhanced on the anode surface under the coactions between the silicate ions and other anions in the electrolyte, which, in turn, accelerated the sparks' moving phenomena around the coatings' surfaces due to the igniting and extinguishing of the sparks appearing alternately on specimen surfaces. Consequently, the macro-scale pits and the micro-cracks caused by the local thermal accumulation had eliminated on the coatings' surfaces. As a result, the corrosion resistance of MAO coatings formed in the electrolyte with sodium silicate was improved obviously by demonstration of the decreasing of the corrosion current density of the coatings with one order of magnitude and increasing of their linear polarization resistance with sixteen times. © Editorial Office of Chinese Journal of Rare Metals. All right reserved.
语种	中文
出版者	Editorial Office of Chinese Journal of Rare Metals
内容类型	期刊论文
源URL	[http://ir.lut.edu.cn/handle/2XXMBERH/115197]
专题	材料科学与工程学院
作者单位	State Key Laboratory of Advanced Processing and Recycling of Non-ferrous Metals, Lanzhou University of Technology, Lanzhou; 730050, China
推荐引用方式 GB/T 7714	Sun, Le,Ma, Ying,Dong, Hairong,et al. Role of Sodium Silicate for Coating Forming on Magnesium Alloys with Micro Arc Oxidation[J]. Xiyou Jinshu/Chinese Journal of Rare Metals,2020,44(4):378-386.
APA	Sun, Le,Ma, Ying,Dong, Hairong,An, Lingyun,&Wang, Sheng.(2020).Role of Sodium Silicate for Coating Forming on Magnesium Alloys with Micro Arc Oxidation.Xiyou Jinshu/Chinese Journal of Rare Metals,44(4),378-386.
MLA	Sun, Le,et al."Role of Sodium Silicate for Coating Forming on Magnesium Alloys with Micro Arc Oxidation".Xiyou Jinshu/Chinese Journal of Rare Metals 44.4(2020):378-386.