Fabrication And Corrosion Resistance Of Superhydrophobic Coatings On Magnesium Surface

Magnesium and its alloys are the next generation of the most promising alloy materials.They are widely used in various fields because of their light weight,high stiffness and good machinability.However,Mg and its alloys have high surface reactivity and they are easily degraded in wet environments or corrosive media containing chloride,which severely limits their large-scale application.Although the traditional surface coating treatment technology can efficiently protect the metal substrate from corrosion,its operation is cumbersome and will cause harm to the environment.Recently,the superhydrophobic coating inspired by the natural organisms has excellent water repellent properties,simple and efficient operation,and the construction of superhydrophobic coating on the surface of Mg ally can greatly improve its corrosion protection property.Three different nanoparticles were used to construct different superhydrophobic composite coatings on the surface of AZ31B Mg alloy.The wettability of superhydrophobic coatings and their corrosion protection ability in 3.5 wt%Na Cl solution were systematically studied.The main research works are as follows:(1)The single-layer superhydrophobic APT@Si O₂ coatings with durability were prepared by mixing octadecyl trimethoxysilane modified APT@Si O₂ nanoparticles and epoxy resin binder on Mg alloy.The prepared coating has excellent superhydrophobicity and mechanical durability.The corrosion protection efficiency reached 99.6%after soaking it in 3.5 wt%Na Cl solution for 2 h,indicating that the superhydrophobic SAS coating has better corrosion protection performance.(2)The double-layer superhydrophobic composite coating based on ZIF-8 nanoparticles was prepared,which consists of the LDH transition layer of the bottom layer and the superhydrophobic ZIF-8 layer of the top layer.Double-layer coating endowed good self-cleaning property of metal and greatly improved corrosion protection ability of Mg alloy.Moreover,the superhydrophobic ZIF-8 based double-layer coating could still maintain excellent anticorrosion performance after 7 days immersion in 3.5 wt%Na Cl solution.(3)Using the special layered structure and hydrophilicity Ti₃C₂T_x the two-dimensional materials,the sandwich-like multi-layer superhydrophobic MXene coating was prepared by combining electrodeposition and spraying.The superhydrophobic MXene coating of multilayer structure could resist the sewage pollution.Furthermore,the mechanical durability and chemical stability of the superhydrophobic coating were investigated,and the surface remained superhydrophobic even after soaking in 3.5 wt%Na Cl solution for4 weeks.More importantly,the superhydrophobic multilayer coating can effectively protect magnesium substrate from corrosion,and its corrosion protection efficiency was 99.999%.