| Water based fluorocarbon chromium free zinc aluminum coating is a kind of two-component anticorrosive coating,which is made of fluorocarbon resin as binder,metal zinc aluminum powder as pigment,and some other additives(dispersant,wetting agent,thickener,defoamer).The coating uses water as solvent and diluent,which can realize self curing at room temperature.The traditional zinc aluminum coating uses oily solvent and needs high temperature Sintering and solidification.The water-based room temperature self curing coating researched in this project has low cost,no pollution to the environment in the production process,simple construction,good corrosion resistance and solvent resistance,and can be widely used in various metal corrosion engineering fields.The traditional zinc-aluminum coating,also known as dacromet,is composed of zinc-aluminum powder,chromate binder,organic solvent,wetting agent,dispersant,and thickener.The coating forms a film on the metal surface through high-temperature sintering and curing It isolates the metal substrate from the outside world,and because zinc is more active than the iron-made metal substrate,it can form a cathodic protection for the substrate and has good corrosion resistance.It is mainly used to prevent corrosion on metal surfaces.However,Dacromet paint is an oil-based paint that requires an organic solvent to fully mix the zinc and aluminum powder with the binder.The production and construction process is harsh,which is also very unfavorable to the environment and the health of the construction personnel,and the chromate binder During the sintering and curing process,there will be unconverted hexavalent chromium ions,and hexavalent chromium is a strong carcinogen.Developed countries have explicitly banned the production and use of chromium-containing zinc aluminum coatings.At present,China also has regulations expressly prohibiting the presence of hexavalent chromium ions in the sale of electronic and electrical products.This research topic aims at the problem that traditional zinc-aluminum coatings require high-temperature sintering and curing,oiliness,and hexavalent chromium ion carcinogens.Fluorocarbon resin(fluorinated acrylic)is used as a binder,and 5: 1 zinc-aluminum mixed powder is used as a pigment.And add thickener,dispersant,defoamer,wetting agent and deionized water to mix,through orthogonal test,priority is given to the corrosion resistance of the coating,followed by the binding force of the coating,and finally the appearance of the coating,Determine the optimal formula of the coating(zinc-aluminum mixed powder 30 g,fluorine-containing acrylic acid 50 g,polyether modified dimethyl siloxane 5g,ethylene glycol 8g,hydroxyethyl cellulose 0.5g,Tween 20 0.5g,deionized water 10g).The coatings prepared in this paper can be self cured in 12 hours at room temperature,and also can be sintered and solidified at 180 ?.The microstructure and film formation of the coatings prepared by the two curing methods are compared and analyzed by means of scanning electron microscopy(SEM),energy dispersive spectroscopy(EDS),X-ray diffraction(XRD),potentiodynamic polarization curve test and electrochemical impedance spectroscopy(EIS)Sex and corrosion products,etc.The results show that the corrosion resistance of the coating is basically the same after curing at regular temperature and sintering.Finally,the influence of silane pretreatment on the performance of the coating was studied.The results showed that the corrosion resistance of the coating was significantly improved by the self-made KH560 silane hydrolysate and MTMS silane hydrolysate.The coating prepared by the pretreatment of MTMS silane hydrolysate had better corrosion resistance,and the immersion time in 3.5wt.% Na Cl solution(pH = 6)could reach 35 d. |
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