Preparation And Properties Of Heavy-duty Anticorrosive Coatings Modified By Graphene Composites

Corrosion phenomena throughout the national economy and national defense construction in all fields.Coating protection is the most commonly used,most direct and most effective protection measure to control corrosion.Graphene,as a kind of ideal twin-crystal nanomaterials,has good mechanical properties,electrical conductivity,thermal stability and photo shielding effect.and can be used as a functional filler to enhance the performance of coatings,and has a very attractive potential prospect in anticorrosive functional coatings.In this paper,self-made metal silane primer was used for pre-treatment.Then,based on the advantages of nanomaterials and epoxy resins（EP）,two different inorganic nanoparticles（nano silica（Si O₂）and nano titanium dioxide（Ti O₂））were grafted onto the GO surface by silane coupling agent（APTES）using GO as the research object.Si O₂-GO and Ti O₂-GO composites were prepared with different mass ratios,then 2wt.%composites were added to prepare epoxy coating materials.The thermodynamic properties and corrosion resistance strength of the coating were studied,and the corrosion resistance mechanism was also studied.The conclusions are as follows:（1）According to the formula,a certain amount of deionized water was first added to the glass beaker,and thenγ-amnopropyl triethoxysilane was slowly added to the beaker.At room temperature（25℃）,it was placed in the magnetic stirrer（800 r/min）for about an hour,so that the silane coupling was fully hydrolyzed,and then anhydrous ethanol was added,and quickly mixed evenly.When there is no oil droplets suspended on the surface of the liquid surface,then slowly add water-based silicone resin,and then add film forming agent after the mixture is uniform,and finally add deionized water to 100 percent.After one month of static storage（continuous monitoring）,the prepared silane treatment agent is stable in state,without flocculation or sediment,and has stable properties.The p H of the original solution of the basic silane treatment agent is about 10,while the p H of the diluent is 7.5.It can be observed from the photos of cast steel plate treated with organosilane that there is no rust on the surface of the plate,and the film forming products are evenly distributed,indicating that silane treatment agent has good corrosion resistance.Adhesion to the coating is very good,no peeling,adhesion performance level one or more,with a kilogram of hammer in the height of 50 cm free fall down,impact coating,paint film and no abnormality,the maximum impact resistance is greater than 50;After the organic silane treatment of self-made sample,there was no rust in the test plate,which lasted for more than 10 days.And because the hydrolyzed silane produced silanol,the silanol group of silanol underwent self-polymerization and homopolymerization crosslinking reaction at high temperature,which greatly improved the corrosion resistance of metal or waterproof wood.In addition,the salt spray resistance of the real test plate can be improved after coating.（2）The improved Hummers method was used to obtain GO.The results show that the go sheet is thin and contains a large number of oxygen-containing functional groups on its surface.Nano-silica（Si O₂）was grafted onto the GO surface using3-aminopropyl triethoxysilane（APTES）,and according to different mass ratios(M_{f-Si O2}:M_f-GO),Si O₂-GO（1:2）,Si O₂-GO（1:3）,Si O₂-GO（1:4）composite materials were prepared.Fourier Transform infrared spectroscopy（FT-IR）,X-ray diffraction（XRD）and scanning electron microscopy（SEM）data proved that nano-Si O₂was grafted onto the GO surface successfully.The dispersion and compatibility of GO in epoxy resin were significantly improved,and Si O₂-GO（1:3）had the best dispersion effect in epoxy resin.The coating mechanical test results show that 2wt.%Si O₂-GO（1:3）reaches grade 0,the impact resistance is 50 cm without crack,and the hardness is 3 H.Electrochemical impedance spectroscopy（EIS）test results show that the composite epoxy coating with a mass fraction of 2wt.%Si O₂-GO（1:3）has the best corrosion resistance,and the resistance value of the coating after immersion is the largest.The Tafel curve of the coating shows that Si O₂-GO（1:3）/EP coating has the highest corrosion potential and the lowest corrosion current.The salt spray resistance test results show that Si O₂-GO（1:3）/EP composite coating has the best corrosion resistance after 360 h neutral salt spray resistance test.（3）The improved Hummers method was used to obtain GO and characterize it.The results indicate that GO sheet is thin and contains a large number of oxygen-containing functional groups on its surface.Nano-titanium dioxide（Ti O₂）was grafted onto GO surface by 3-aminopropyl triethoxysilane（APTES）,and Ti O₂-GO（1:2）,Ti O₂-GO（1:3）and Ti O₂-GO（1:4）composites were prepared according to different mass ratios(M_{f-Ti O2}:M_f-GO).Fourier transform infrared spectroscopy（FT-IR）,X-ray diffraction（XRD）and laser scanning electron microscopy（SEM）results showed that nano Ti O₂was successfully grafted onto the surface of GO,and the dispersion and compatibility of GO in epoxy resin coating were significantly improved.Ti O₂-GO（1:3）had the best uniform dispersion effect in epoxy resin coating.The test results of mechanical properties of the coating also showed that2wt.%Ti O₂-GO（1:3）reached level 0,impact resistance 50 cm without crack,hardness 3 H;Electrochemical impedance spectroscopy（EIS）test results show that the composite epoxy coating with the mass fraction of 2wt.%Ti O₂-GO（1:3）has the best corrosion resistance,and the resistance value of the coating after immersion is the highest.The Tafel curve of the coating shows that the Ti O₂-GO（1:3）/EP coating has the highest corrosion potential and the lowest corrosion current.Salt spray test results show that Ti O₂-GO（1:3）/EP composite coating has the best corrosion resistance after 360 h neutral salt spray test.