| Magnesium alloys are the lightest metal structural materials with high strength-weight ratio,high thermal conductivity,excellent electromagnetic shielding characteristics,good processability and so on,which make them widely used in many fields.However,magnesium alloys have certain limitations,and they are very vulnerable to corrosion,which seriously limits the development and application of magnesium alloys.Therefore,the key to expand the application of magnesium alloys is to improve the corrosion resistance of magnesium alloys.Three superhydrophobic composite coatings were prepared in this paper.The morphology and composition of the coatings and ZnO particles were characterized by SEM,EDS,XRD and FT-IR.The adhesion of the coatings was evaluated by scratch method,tape stripping method and sandpaper wear method.The corrosion resistance and wear resistance of the coatings were investigated by static contact angle test,friction wear and electrochemical workstation.The main contents of this paper are as follows:Superhydrophobic coatings with double-layer structure of ZnO/Ce conversion coatings were prepared by preparing cerium conversion coatings on etched magnesium alloys and spraying hydrophobic ZnO nanoparticles.The effect of hydrogen peroxide concentration on the morphology of cerium conversion coating was investigated.The results showed that the coating had the best effect when the concentration of hydrogen peroxide was 0.07 mol/L.After spraying hydrophobic ZnO nanoparticles,the contact angle and sliding angle of the coating were 159.3° and 8°.The friction and wear tests of blank magnesium alloy,etched magnesium alloy and magnesium alloy with superhydrophobic coating showed that the coating had certain wear resistance.In addition,the coating also showed excellent stability,self-cleaning and corrosion resistance.Cluster-like ZnO/epoxy superhydrophobic coatings were prepared by controlling the ratio of ZnO nanoparticles to epoxy resin to expose part of ZnO on the surface,then growing ZnO nanorods and modifying them with stearic acid to get low surface energy.The effects of the mass ratio of ZnO nanoparticles to epoxy resin and the concentration of Zn?NO3?2 growth solution on the morphology and wettability of superhydrophobic coatings were investigated.The results showed that when the ratio of ZnO to epoxy resin was 10:2 and the concentration of Zn?NO3?2 growth solution wais 2.5 mmol/L,the coating achieved the best effect.At this time,the contact angle was 155.9° and the sliding angle was 8.7°.The scratch method and tape peeling test proved that the coating had excellent adhesion to the magnesium alloy substrate.After immersing the coating in 3.5 wt% NaCl solution for 28 days,the impedance of the coating was still higher than that of the blank.At the same time,the coating also had good wear resistance,self-cleaning and stability.Flower-like ZnO/PDMS superhydrophobic coatings were prepared by mixing hydrophobically modified ZnO microspheres with polydimethylsiloxane in a certain proportion and spraying on magnesium alloys,sponges and other substrates.The effect of sodium citrate concentration on the morphology of ZnO was investigated.It was found that 0.06 mol/L was the optimum addition concentration of sodium citrate.The effect of the ratio of ZnO microspheres to PDMS resin on the morphology,adhesion and wettability of superhydrophobic coatings were investigated.The results showed that when the ratio of ZnO microspheres to PDMS resin was 2:1,the coatings had good adhesion and no surface agglomeration,and the contact angle was 151.3°.Lattice method,tape peeling and sandpaper wear tests proved that the coating had excellent adhesion.The prepared superhydrophobic coating could be applied on different substrates,and the water contact angle wais above 150°,the coating sprayed on the sponge showed excellent oil-water separation performance.In addition,the coating also had good anti-icing,self-cleaning and corrosion resistance. |
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