| Stainless steel is widely used in various fields due to its excellent mechanical properties,corrosion resistance and aesthetics.However,the disadvantages of pitting corrosion in a humid environment and poor heat transfer performance due to hydrophilicity are still not avoided.In this paper,for the problem of stainless steel,cerium oxide coating was prepared on the surface by cathodic electrodeposition.And the super-hydrophobic properties of the coating are imparted by subsequent vacuum treatment and stearic acid modification.The effects of deposition temperature,current density,electrolyte concentration and deposition time on the surface morphology and phase composition of the coating were studied.The formation mechanism of the coating and the hydrophobic properties,thermal stability,chemical stability,self-cleaning properties and corrosion resistance of the superhydrophobic coating obtained under the two different treatment methods were analyzed.The study found that the deposition process parameters affect the morphology of the coating,but do not change the phase composition of the coating.The resulting coatings are all cerium oxide coating.With the increase of deposition temperature,the morphology of the coating is transformed from a small layered upper spherical hierarchical structure to a single-layer structure with multiple pits on the surface.Then the morphology is gradually finer,and the crack between the underlying blocks is reduced.With the increase of time,the coating grows into a hierarchical structure from a single-layer structure,and then the bulk and cracks become larger,and the hierarchical structure disappears.The effects of current density and electrolyte concentration on the morphology of the coating are coupled to each other.Low current density requires a high electrolyte concentration to obtain a uniform micro-nano-graded structure.When the deposition temperature is 25℃,the current density is 2.2 mA/cm~2,and the electrolyte concentration is 0.1 mol/L,the coating can be superhydrophobic after vacuum treatment and stearic acid modification.And their corresponding water contact angles are 160.59°and 166.22°.The superhydrophobic coating obtained after vacuum treatment can maintain the contact angle above 150°after 7 thermal cycles.The contact angle reached146.61°after heat treatment at 205°C.It shows that it has good thermal stability.At the same time,the coating also has excellent corrosion resistance.The corrosion current density is reduced by three orders of magnitude with respect to the substrate,and the pitting potential is increased by nearly 1 V vs.SCE,which effectively reduces the sensitivity of the substrate to pitting.In addition,the coating also has self-cleaning properties and chemical stability.The superhydrophobic coating obtained after the stearic acid modification was kept in a hydrophobic state after 7 heat cycles,and the contact angle was lowered to 135.07°after heating at a high temperature of 205°C.The contact angles measured on the surface of different pH solutions are more than 150°,indicating that the chemical stability of the coating is good,but the corrosion resistance of the coating is lower than that of the vacuum treated coating.The corrosion current density is relative to the substrate.The corrosion current density is reduced by two orders of magnitude relative to the substrate,and t he corrosion potential is increased by 0.498V vs.SCE relative to the substrate. |
