The Fabrication Of Superhydrophobic Surface On Magnesium Alloy And Its Corrosion Protection,Antifouling Performance

With the rapid growth of the global economy in recent years,human demand for energy is also increasing.Meanwhile the one hand we need to continue to develop new energy sources,on the other hand also need to consider energy saving.Magnesium and its alloys due to its low density and high specific strength has been widespread concern worldwide.In recent years,its field of application has been extended to many areas automotive,aerospace,electronics,biomedical,etc.However,due to the high chemical reactivity of magnesium and its alloys,resulting in a magnesium alloy susceptible to corrosion damage,which greatly affected the application of magnesium and its alloys in various fields.With the general surface corrosion technologies,due to its superhydrophobic film having excellent hydrophobic properties,and therefore the film will not be wet etching solution,thus fundamentally improving the corrosion protection of the metal substrate.So prepared superhydrophobic surface layer on magnesium and its alloys it from the hazards of corrosive media and to explore its anti-corrosion mechanism has become a research hotspot in recent years.In this paper,AZ31 Mg alloys acted as the research objects,and some different synthesis methods,such as:solution immersion method,water bath method and hydrothermal synthesis method,have been used to fabricate superhydrophobic films with some rough structure.The morphologies,structures and compositions of superhydrophobic films were characterized by SEM,FT-IR and XPS,respectively.Furthermore corrosion resistance performance of superhydrophobic films were investigated by IE and EIS.Use digital photos and SEM to study superhydrophobic film antifouling ability by natural waters watery coupon.Using a simple solution immersion on the AZ31 magnesium alloy substrate surface in situ to build a Mg[CH₃（CH₂）₁₂COO]₂ sheet structure.After testing in an alcohol water ratio of 1:1,the mixed reaction solution myristic acid concentration 0.25 mol/L,the reaction time was 24 h,uniform film growth on the surface of the static water contact angle of the maximum value reached 152°.Tested soaked in 3.5 wt.%NaCl solution for 3 h,corrosion current density superhydrophobic layer of magnesium alloy cover declined an order of magnitude than the blank magnesium alloy,and the impedance value of its Nyquist diagram from about 100Ωincreased to about 1000Ω.Using a simple,quick water bath method was used to prepare a Fe[CH₃（CH₂）₁₂COO]₃ sheet structure of a film on the surface of AZ31 magnesium alloy substrate.The reaction mixture solution at a concentration of contrast ratio is 1:1,the mixed reaction solution myristic acid concentration 0.1 mol/L,the reaction temperature is 60℃,the reaction time was 2 h,to form a flat surface layer,preferably hydrophobic properties,static water contact angle reaches 165°.After the corrosion test,immersion in 3.5 wt.%NaCl solution for 3 h,corrosion current density super-hydrophobic layer covering magnesium alloy decreased three orders of magnitude,the Nyquist plot of impedance value of about 8×10⁴Ωfar higher than that of magnesium alloys is about 100Ω.By immersion in natural waters found in water samples at different time,superhydrophobic coatings soaked in 30 days still no microbial attachment,although the hydrophobic capacity decrease occurred,but its rough structure is still intact,while the magnesium alloy in the blank has been soaked for 30 days severe corrosion,which surface has been covered with microbial secretions.Using a simple hydrothermal method to prepare a sheet structure consisting of a flower-like composite structure Ni[CH₃（CH₂）₁₆COOH]₂ and Ni[CH₃（CH₂）₁₆COOH]₃ film.The reaction mixture solution at a concentration of contrast ratio is 1:1,the mixed reaction solution myristic acid concentration 0.005 mol/L,the reaction temperature is 150℃,the reaction time was 8 h,to form a flat surface layer,preferably hydrophobic properties,static water contact angle reaches158°.Meanwhile By comparing the first two chapters of the data found that the use of longer carbon chain organic acids increase the contact angle of the film for the preparation of no significant effects.In the corrosion test immersed in 3.5 wt.%NaCl solution for 2 h,there is corrosion current density super-hydrophobic layer covering magnesium alloy decreased two orders of magnitude,the Nyquist plot of impedance value of about 2×10⁴Ωmagnesium alloy is much larger than the blank about 200Ω.