Study On Preparation And Corrosion And Wear Resistance Of Laser-textured Superhydrophobic Surface Of Magnesium Alloy

Magnesium alloys are easily corroded due to the strong activity of magnesium metal,which limits their application in extreme working conditions and harsh environments to a certain extent.Improving the corrosion resistance of magnesium alloys has important practical significance for the application of magnesium alloys.In addition,during the friction process of magnesium alloy superhydrophobic surface,the superhydrophobic performance will be greatly reduced due to the destruction of the surface structure or chemical coating.Therefore,how to prepare a strong and wear-resistant magnesium alloy super-hydrophobic surface is an urgent problem to be solved.This article takes AZ31 magnesium alloy as the research object,and realizes the controllable preparation of surface micro-nano structure through laser surface texturing technology.Two methods of laser-chemical etching and liquid laser ablation are used to prepare magnesium alloy super-hydrophobic surface,and to explore its corrosion resistance and wear resistance,aiming to improve different properties and expand its application in different fields.The main findings are as follows:(1)Determine the laser processing plan for the combination of groove spacing and groove width,analyze surface topography and wettability changes.By introducing the theoretical model of wettability and the actual model of the sample surface,the ratio f of the solid-liquid contact surface to the total solid-liquid-gas contact surface is calculated.Through analysis of the ratio f,the apparent contact angle?_C-B and the actual measured value of the contact angle?,it can be seen that when the area fraction f of the solid-liquid interface is between 10.4%-15.7%,a larger actual contact angle can be obtained.When f is less than 3.2%,because the solid-liquid contact area is too small,the liquid will immerse into the grooves of the microstructure,making the surface hydrophilic.When f is greater than 22.2%,as the solid-liquid contact area increases,the wettability becomes worse and the contact angle becomes smaller.(2)Using laser-chemical etching method to prepare super-hydrophobic surface with micro-nano composite texture.Through chemical composition analysis,determine the reason for its wettability transformation;through electrochemical experiments to explore its corrosion resistance and analyze its mechanism.XPS shows that the C-C(H)bond content of the LST-CE sample is 32.26%higher than that of the original sample,indicating that the non-polar bond content has increased.This is due to the non-polar short-chain organic molecules in the air being adsorbed on the surface of the material.The wettability analysis believes that the superhydrophobic surface is the result of the combined effect of the decrease of surface free energy caused by the increase of micro-nano texture and non-polar bond content.Electrochemical experiments show that the corrosion resistance of the samples has been improved to a certain extent,which is due to the formation of a"cavity"in the micro-nano texture and trapping air.When the metal contacts the corrosive liquid,a solid-liquid-gas three-phase interface is formed,and the corrosive ions cannot directly contact the substrate,which significantly slows down the corrosion rate of the metal.(3)A liquid-phase laser ablation method is used to prepare a super-hydrophobic surface in one step.Analyze chemical composition changes through EDS,and analyze its wettability and wear resistance through manufacturing process and wear resistance mechanism.The EDS energy spectrum shows that as the number of wear increases,the relative content of C and F elements gradually decreases,but still maintains a high value after 400 wears.The wettability as a whole tends to be stable,and the contact angle is maintained at about 120°.According to the analysis of the manufacturing process,the F element in the fluorosilane solution is present on the surface and inside of the stacked layer as the molten material is stacked,so the surface has good repairability.The analysis of the wear resistance mechanism believes that the hydrophobic coating on the surface is a network structure composed of a fluorinating agent containing F element.When the surface is worn,the active agent containing F element is refilled into the damaged area at this time,and the mesh structure be repaired.Therefore,after repeated abrasion,the surface of the sample still maintains high hydrophobicity.