Corrosion Resistance Of The Non-fluorinated Superhydrophobic Coatings On Iron Via Spraying

The chemical and electrochemical reactions between the material and the surrounding medium will cause corrosion and damage it.Preparing a super-hydrophobic coating on the surface of the material can effectively improve its corrosion resistance.So far,researchers have developed a variety of preparation methods for superhydrophobic surfaces of metal substrates.However,most of these methods use fluorine-containing reagents as one of the raw materials,using chemical or electrochemical etching,electrodeposition and other means.Fluorine-containing reagents are expensive and harmful to environmental safety and human health;however,chemical or electrochemical etching,electrodeposition and other means are not conducive to large-scale production applications.Based on this,this paper uses fluorine-free zinc oxide / vegetable oil or cold galvanized spray paint as the raw material,and uses a spray process to prepare a super-hydrophobic coating on the surface of metal iron.The wettability,surface morphology and surface composition of the sample were analyzed by contact angle measuring instrument,scanning electron microscope,energy spectrometer,etc.Soaking,neutral salt spray),friction resistance and other properties have been studied,the specific research content and results are as follows:(1)Preparation of zinc oxide/vegetable oil superhydrophobic surface and research on its corrosion resistance.Carried out with a low surface energy material(KH570)as a modifier for modified nano zinc oxide powder,the powder and the modified sunflower oil was then uniformly mixed in a chloroform solution,and sprayed simple heat treatment on an iron surface,By controlling the ratio of oil to the nanoparticles to obtain a coating having a super-hydrophobic.The study found that when the mass ratio of oil to modified nanoparticles was 0.9: 1,the performance of the coating reached a relatively balanced level in terms of wettability,stability,and corrosion resistance.The water contact angle of the coating was 158.1° ± 2.3° with a sliding angle of 5.1° ± 0.5°.After60 minutes of ultrasound,the contact angle decreased to 138.6° ± 1.3°,and the sliding angle increased to 34.2° ± 1.1°;The surface contact angle of the sample is higher than150° after treatment at different temperatures(-30 ? 270?)for 60 min;after 1000 cm of wear under a pressure of 250 Pa,the contact angle of the coating is reduced to about142°,The sliding angle is increased to approximately 10°;The sample contact angle is always greater than 145° after soaking in different p H solutions for 100 h;The superhydrophobic samples were immersed in a static or dynamic aqueous solution of Na Cl(3.5 wt.%)to study the changes in corrosion resistance and surface wettability.The results show that the duration of the superhydrophobic sample in the static solution is about 10 d,and as the flow rate of the corrosive solution increases to 2 m/s,it drops sharply to 24 h.This work shows that the development of environmentally friendly and non-toxic micro-nanoscale super-hydrophobic anticorrosive coatings from sustainable and renewable resources has broad prospects and can be a simple and effective method for metal anticorrosion.(2)Preparation and Corrosion Resistance of Zinc-Rich Superhydrophobic Zinc Coatings and study on its corrosion resistance.A cold galvanized paint is sprayed on the iron substrate,and then etched with an acetic acid(HAc)solution to obtain a metal zinc layer having a micro-nano structure.Subsequent stearic acid(STA)hydrophobization treatment makes the surface superhydrophobic.The prepared superhydrophobic sample has a contact angle of 168.4° ± 1.5° and a sliding angle of 3.5° ± 1.2°.After the sample was put into ethanol for 120 minutes,the contact angle decreased slightly to 150.6° ±1.1°,and the sliding angle increased to 13.9° ± 1.3°.The coating adhesion test showed that the superhydrophobic coating adhered to the iron substrate at a level of 5B.After 10cycles(about 200 cm)under a pressure of 250 Pa,the micro/nanostructures on the sample were almost destroyed,and the contact angle on the surface of the sample was reduced to about 120°.But after the worn samples were immersed in the HAc aqueous solution and the STA ethanol solution,micro/nano structures still appeared on the surface,and the coating recovered its original superhydrophobicity.The samples were immersed in a static or dynamic aqueous solution of Na Cl(3.5 wt.%)and a salt spray environment,and the changes in their corrosion resistance and surface wettability were studied,and the surface morphology and surface composition were monitored.The results show that the lifetime of the superhydrophobic sample in the static solution is8?10 d,and it decreases sharply to 12 h as the flow rate of the corrosive solution increases to 2 or 4 m/s.It can be said that the superhydrophobic surface provides 8?10 d extra corrosion protection for zinc coating.