Preparation And Characteristics Of Superhydrophobic Surface On AZ91D Magnesium Alloy With Spraying Method

Magnesium alloy,as one of the lightest structural metal materials,has a wide range of applications,but because of its poor corrosion resistance there is a lot of risk to use.Magnesium alloy superhydrophobic surface has many special functions.However,most of its existing preparation methods have technical defects such as equipment shape limitations and complicated processes,which make it difficult to achieve industrialization.Therefore,it is significant to study the spraying method to prepare superhydrophobic surface which does not limit the shape and size of the substrate and has high preparation efficiency.In this paper,the research object is AZ91 D magnesium alloy,with the purpose of preparing superhydrophobic surface with acceptable binding force and corrosion resistance,systematic research and process optimization are carried out.The main research work and results of the paper are as follows:(1)Condition selection and formulation optimization of spraying process.Taking the stability of the coating and the appearance quality and hydrophobicity of the coating as evaluation indicators,the dispersion process of the coating is screened and optimized,and the single-factor experiment is used to systematically study the influence of the effective components of the coating and its process parameters,through the contact angle The optimal process determined by the test is as follows: 0.5 g/LA,0.5 g/L CNTs,0.2 mL/L FAS,40 mL/L TEOS,ethanol solvent,mechanical stirring for 10 min,ultrasonic vibration for 30 min,and then resume mechanical stirring for 30 min;The dosage of paint is 40 mL,and the paint temperature is 25 ??35 ?.(2)Optimization of spraying process based on pretreatment.In order to improve the binding force and corrosion resistance of the coating,the hydrolyzate of spraying silane coupling agent is added as a binder for pretreatment.Through single-factor experiment,the coating is adjusted and optimized,and the influence of pretreatment process and curing process parameters is systematically studied.The optimal process determined by contact angle test and spot test is as follows: the binder is 200 mL/LB,80 mL/L H2 O,ethanol solvent,take 10 mL for spraying after 30 minutes of hydrolysis,and spray 45 mL of hydrophobic coating within 3-6 minutes after completion,the coating is 1 g/LA,2 g/L CNTs,0.2 mL/L FAS,40 mL/L TEOS,ethanol solvent,cured at 120 ? for 2 h after spraying.(3)Performance test and analysis of typical samples.Analyze the hydrophobicity,surface morphology and composition,binding force and corrosion resistance of the coating prepared by the best process conditions after pretreatment.The hydrophobicity test results show that the contact angle of distilled water is 154.5°,the rolling angle is 1°,and it has p H stability.SEM test shows that the surface of the coating is covered with a layer of micron-level undulations and a three-dimensional micro/nano-level rough structure with a nano-scale network.The test results of the cross-cut method show that the binding force is improved from 0B level to 5B level after the introduction of the pretreatment process.The drip test results show that the discoloration time is 17 times higher than that of the magnesium matrix,and the corrosion resistance is improved.