Preparation and Performance of Plasma/Polymer Composite Coatings on Magnesium Alloy

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• 作者：H. R. Bakhsheshi-Rad ; E. Hamzah…
• 关键词：corrosion behavior ; hydrophobic properties ; mechanical properties ; Mg alloy ; triplex coating
• 刊名：Journal of Materials Engineering and Performance
• 出版年：2016
• 出版时间：September 2016
• 年：2016
• 卷：25
• 期：9
• 页码：3948-3959
• 全文大小：3,076 KB
• 刊物类别：Chemistry and Materials Science
• 刊物主题：Chemistry
  Characterization and Evaluation Materials
  Materials Science
  Tribology, Corrosion and Coatings
  Quality Control, Reliability, Safety and Risk
  Engineering Design
  
• 出版者：Springer New York
• ISSN：1544-1024
• 卷排序：25

文摘

A triplex plasma (NiCoCrAlHfYSi/Al₂O₃·13%TiO₂)/polycaprolactone composite coating was successfully deposited on a Mg-1.2Ca alloy by a combination of atmospheric plasma spraying and dip-coating techniques. The NiCoCrAlHfYSi (MCrAlHYS) coating, as the first layer, contained a large number of voids, globular porosities, and micro-cracks with a thickness of 40-50 μm, while the Al₂O₃·13%TiO₂ coating, as the second layer, presented a unique bimodal microstructure with a thickness of 70-80 μm. The top layer was a hydrophobic polymer, which effectively sealed the porosities of plasma layers. The results of micro-hardness and bonding strength tests showed that the plasma coating presented excellent hardness (870 HV) and good bonding strength (14.8 MPa). However, the plasma/polymer coatings interface exhibited low bonding strength (8.6 MPa). The polymer coating formed thick layer (100-110 μm) that homogeneously covered the surface of the plasma layers. Contact angle measurement showed that polymer coating over plasma layers significantly decreased surface wettability. The corrosion current density (i_corr) of an uncoated sample (262.7 µA/cm2) decreased to 76.9 µA/cm2 after plasma coatings were applied. However, it was found that the i_corr decreased significantly to 0.002 µA/cm2 after polymer sealing of the porous plasma layers.