Preparation and properties of superhydrophobic epoxy composite coatings on magnesium alloys

Abstract

The traditional preparation process of superhydrophobic surfaces(SHS) is complicated and the mechanical stability of SHS is less than satisfactory in most cases, which seriously restricts the practical application. The "binder+nanoparticles" strategy was used to prepare a nonfluorinated, durable and stable superhydrophobic epoxy composite coating on magnesium alloy. The contact angle test results show that the maximum contact angle of the composite coating is 160.2°, and the contact angle is still as high as 103° even after 30 days of soaking in 3.5%(mass fraction) NaCl solution; EIS results indicate that the |Z|0.01 Hz of the composite coating is still above 109 Ω·cm2 even after five accelerated aging cycles, demonstrating excellent resistance to salt fog and anticorrosion performance; Friction and wear test results reveal that the |Z|0.01 Hz of the composite coating is as high as 1.84×109 Ω·cm2 after mechanical friction under 19.6 N load for 8 h. Due to the excellent blocking barrier of "air cushion", the composite coating can provide efficient and durable corrosion protection for magnesium alloy and the "adhesive+nanoparticles" strategy provides a new direction for the preparation of superhydrophobic coating.

Keywords

• magnesium alloy
• superhydrophobic coating
• corrosion protection
• epoxy coating