|Effect of SiC particles on microarc oxidation process of magnesium matrix composites|
|Y. Q. Wang; X. J. Wang; W. X. Gong; K. Wu; F. H. Wang
|Source Publication||Applied Surface Science
|Abstract||SiC particles are an important reinforced phase in metal matrix composites. Their effect on the microarc oxidation (MAO, also named plasma electrolytic oxidation-PEO) process of SiCp/AZ91 Mg matrix composites (MMCs) was studied and the mechanism was revealed. The corrosion resistance of MAO coating was also investigated. Voltage-time curves during MAO were recorded to study the barrier film status on the composites. Scanning electron microscopy was used to characterize the existing state of SiC particles in MAO. Energy dispersive X-ray spectrometry and X-ray photoelectron spectroscopy were used to analyze the chemical composition of the coating. Corrosion resistance of the bare and coated composites was evaluated by potentiodynamic polarization curves in 3.5% NaCl solution. Results showed that the integrality and electrical insulation properties of the barrier film on the composites were destroyed by the SiC particles. Consequently, the sparking discharge at the early stage of MAO was inhibited, and the growth efficiency of the MAO coating decreased with the increase in the volume fraction of SiC particles. SiC particles did not exist stably during MAO; they were oxidized or partially oxidized into SiO2 before the overall sparking discharge. The transformation from semi-conductive SiC to insulating SiO2 by oxidation restrained the current leakage at the original SiC positions and then promoted sparking discharge and coating growth. The corrosion current density of SiCp/AZ91 MMCs was reduced by two orders of magnitude after MAO treatment. However, the corrosion resistances of the coated composites were lower than that of the coated alloy. (C) 2013 Elsevier B.V. All rights reserved.|
|description.department||[wang, y. q.
; gong, w. x.
; wang, f. h.] harbin engn univ, educ minist, key lab superlight mat & surface technol, corros & protect lab, harbin 150001, peoples r china. [wang, x. j.
; wu, k.] harbin inst technol, sch mat sci & engn, harbin 150001, peoples r china. [wang, f. h.] chinese acad sci, inst met res, state key lab corros & protect, shenyang 110016, peoples r china.
; wang, yq (reprint author), harbin engn univ, educ minist, key lab superlight mat & surface technol, corros & protect lab, harbin 150001, peoples r china.
Metal Matrix Composite
Y. Q. Wang,X. J. Wang,W. X. Gong,et al. Effect of SiC particles on microarc oxidation process of magnesium matrix composites[J]. Applied Surface Science,2013,283:906-913.
Y. Q. Wang,X. J. Wang,W. X. Gong,K. Wu,&F. H. Wang.(2013).Effect of SiC particles on microarc oxidation process of magnesium matrix composites.Applied Surface Science,283,906-913.
Y. Q. Wang,et al."Effect of SiC particles on microarc oxidation process of magnesium matrix composites".Applied Surface Science 283(2013):906-913.
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