Corrosion, absorbing and conductivity property of MG-Nb2O5-MgO composite coatings on surface of magnesium alloys
Chang Liu, Quantong Jiang, Xiaofan Zhai, Xia Zhao, Jizhou Duan, Baorong Hou
Abstract
• The MgO@Nb 2 O 5 composite film was prepared on the surface of Mg-7Y binary alloy by micro-arc oxidation. On the basis of the MgO@Nb 2 O 5 composite film, MG-Nb 2 O 5 − MgO composite coatings were prepared by adding MG by scraping method. The whole process was simple. The added substances were harmless to human body and environment. • Electrochemical tests showed that MG-Nb 2 O 5 − MgO composite coatings improved the corrosion resistance of Mg-7Y binary alloy. • Conductivity test showed that MG-Nb 2 O 5 − MgO composite coatings changed the insulation properties of the MgO@Nb 2 O 5 composite film. The addition of MG improved the conductivity of MG-Nb 2 O 5 − MgO composite coatings. • Vector network analyzer test showed that MG-Nb 2 O 5 − MgO composite coating had a certain absorbing properties. When the thickness of the MG coating was 20μm, the MG-Nb 2 O 5 − MgO composite coating showed a certain absorbing performance. MG-Nb 2 O 5 − MgO composite coatings were fabricated on surface of magnesium alloy using a scraping method, based on MgO@Nb 2 O 5 micro-arc oxidation film. Conductivity, corrosion resistance, and wave absorption properties of the composite coatings were investigated through surface morphology and microstructure analysis, thickness measurements, electrochemical tests, conductivity tests, and wave absorption performance analysis. SEM, Raman spectroscopy, energy-dispersive X-ray spectroscopy, laser confocal microscopy, and X-ray diffraction results reveal that, compared to MgO@Nb 2 O 5 micro-arc oxidation coating, surface pores and cracks of MG-Nb 2 O 5 − MgO composite coating were reduced. Surface roughness and hardness were reduced. The primary components of MG-Nb 2 O 5 − MgO composite coating were carbon and magnesium silicate. Conductivity results indicate that MG-Nb 2 O 5 − MgO composite coating exhibited electrical conductivity. As MG coating thickness increased, conductivity also increased progressively. Kelvin probe and electrochemical results demonstrate that corrosion potential increased, while corrosion current decreased after applying MG coating. Corrosion resistance was enhanced. MG coating exhibited optimal corrosion resistance at a thickness of 10 μm. Vector network analyzer test results indicate that the coating demonstrated measurable wave absorption performance at a thickness of 20 μm.