| Magnesium alloys have good development prospects in the field of biomedicine as bone implants due to their good biocompatibility and fully degradable properties.However,due to their active chemical properties,easy loss of electrons,and corrosion resistance in humid environments very poor.Inspired by bionics,a superhydrophobic film is prepared on the surface of magnesium alloys to block and isolate the magnesium alloy matrix and simulated body fluid(SBF),which can reduce the corrosion rate of magnesium alloys and maintain normal mechanical properties in the human body.Service time in the human body helps a lot.In this paper,simple and efficient anodic oxidation and hydrothermal methods are used to study the effects of different parameters of the two processes on the microscopic morphology and performance of the film,and to explore its electrochemical properties and corrosion degradation behavior in SBF.The following research results:(1)Using the anodizing process,the optimal process parameters were selected through single-factor parameter optimization under different electrolyte concentrations,voltages and anodizing times:when the electrolyte concentration was 0.5 mol/L,the voltage was 50 V,and the anodizing time was 45 min,the micro/nano-scale composite protrusions-particle structure with uniform size and dense particles were prepared on the surface of magnesium alloy,and the contact angle was 156.99°.The electrochemical test in SBF shows that the corrosion potential is-1.388V,the corrosion current density is 6.178×10-8 A/cm~2,the maximum AC impedance radius is 11.2K?·cm~2,the corrosion potential is-1.588 V,and the corrosion current density is The corrosion resistance of the magnesium alloy matrix with a maximum value of 3.498×10-~5 A/cm~2 and the AC impedance radius of about 370?·cm~2 is significantly enhanced.After ten days of immersion in SBF,the corrosion potential decreased to-1.515 V,the current density increased to 5.40×10-6A/cm~2,and the maximum value of the AC impedance radius decreased to about 3.95 K?·cm~2,still maintaining good resistance.corrosive.During the test soaking process,the p H of the solution increased first and then decreased,and the mass change of the sample also showed a trend of first weight loss and then weight gain,and the corrosion rate became smaller and smaller.Experiments show that the micro/nano-scale composite protrusions-particle structure generated by the magnesium alloy matrix after anodization,after being modified by stearic acid,has long-lasting and stable corrosion resistance after immersion in simulated body fluids.(2)Using the hydrothermal process,the optimal process parameters were screened through single-factor parameter optimization at different temperatures,times and solution concentrations:when the hydrothermal temperature was 100°C,the hydrothermal time was 6 h and the solution concentration was 1.0 mol/L,a multi-layered,free-growing and uniformly dense micro/nano-scale needle-like composite structure was formed on the surface of the magnesium alloy,with a contact angle of 159.04°.The electrochemical test in SBF shows that the corrosion potential is-1.338 V,the corrosion current density is 3.498×10-10 A/cm~2,the maximum AC impedance radius is 15.16 K?·cm~2,and the magnesium alloy matrix also shows strong corrosion resistance.After ten days of immersion in simulated body fluids,the corrosion potential decreased to-1.458 V,the current density increased to 4.245×10-7 A/cm~2,and the maximum value of the AC impedance radius decreased to about 7.68 K?·cm~2.During the test soaking process,the p H of the solution has been increasing,but the growth rate is getting slower and slower,the weight of the sample is decreasing,the corrosion rate is also decreasing,and the p H value is still lower than 10.0 after ten days.Experiments show that the micro/nano-scale composite needle-like structure formed by the magnesium alloy matrix after hydrothermal treatment also has stable corrosion resistance after being modified by stearic acid and immersed in simulated body fluids.(3)Two processes of anodic oxidation and hydrothermal method have prepared corrosion-resistant and corrosion-resistant films with different microstructures but with super-hydrophobic function on the surface of magnesium alloy.The corrosion resistance performance is better,but the hydrophobic film formed by the anodizing process increases in weight in the later stage of SBF immersion,and its p H also shows a downward trend,which is different from the immersion process of the hydrothermal process. |
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