| Waterborne inorganic Zinc-rich paint is a kind of paints for heavy duty corrosion protection which comprises of alkali metal silicate binders, Zn dust as anticorrosion pigment and other additives. It is completely different from the traditional solventborne type paints for its zero volatile organic compounds (VOC) feature. Besides, the key performance characteristics of water-borne inorganic Zinc-rich paints are convenience for use, and excellent corrosion protection,adhesion,weather resistance,abrasion resistance,heat resistance,organic resistance,radiation resistance, etc. The widely used waterborne inorganic paints nowadays use the high SiO2/K2O molar ratio potassium silicate aqueous as binder, which was developed by the National Aeronautics and Space Administration (NASA) of America in 70s of the 20th century. The SiO2/K2O molar ratio of this type of paint reached 5.3:1 to achieve self-curing. Now, potassium silicate waterborne inorganic Znic-rich paints with high SiO2/K2O molar ratio have been widely used for corrosion protection globally. However, in our country the study of such paint is just at the beginning line with poor technique and relative works are all in laboratory. The huge market of high SiO2/K2O molar ratio potassium silicate zinc-rich paint in our country still depends on imports. Therefore, promotion of studies on this type of paint to realize domestic production is significant. In this paper, serial work was carried on from preparation of high SiO2/K2O molar ratio potassium silicate aqueous to determination of the paint performance. The main results obtained in this paper are shown as follows:1. Impact of reaction temperature, type of agitation, speed of adding silica sol, variety and quantity of silane coupling agent, and water soluble organic silicon large molecular compounds on preparation of high SiO2/K2O potassium silicate aqueous has been studied. Results show that reaction temperature between 50～60oC is proper to prepare potassium silicate aqueous with better transparence. Transmission electron microscopy (TEM) revealed that particle size in the potassium silicate aqueous produced at 60oC is smaller. Transparence of products produced with magnetic agitation to form stable votex in the solution is better than that with mechanical agitation. Adding speed of silica sol and silane coupling agents has substantial effect on stability of the final products. Methyl-trimythylosilane andγ-aminopropyl trimythylosilane promote dispersion of high molar ratio potassium on the mild steel sheet substate. The organic silicon large molecular compounds enforeced stability of the products, and the sheft life can reach 120d. Laser particle size analysizer indicate that particle size of the product produced in this paper is less than 150nm.2. Basic performance of high molar ratio potassium silicate waterborne Znic-rich paint prepared in this work are determined. Results show that basic performance of products of ourselves reach or even beyond the according performance of products on sale. Increase of molar ratio of binder can shorten paint surface dry time, and increase of solid content in potassium silicate binder has the same effect. Scanning electron microscope (SEM) demonstrated that increase of SiO2/K2O molar ratio of potassium silicate enforces the binding between zinc particles in the coatings, and decreases holes among the zinc particles. But if the SiO2/K2O molar ratio of potassium silicate is too high, cracks increase on the paint surface. In this work, controlling the SiO2/K2O molar ratio between 5～7 is proper. The high molar ratio potassium silicate Znic-rich paint prepared in this work can work at 400oC for long time, and after that there isn't crystal type change of SiO2 which play a role as binder in the coating.3. The electrochemical behavior of high SiO2/K2O potassium silicate waterborne inorganic Zinc-rich paint in 3.5%NaCl solution are studied by using electrochemical impedance scopy (EIS) technology. SEM was employed to observe the structure change of the paint.Results show that paint electrical conductivity increase with SiO2/K2O molar ratio of potassium silicate aqueous, but the corrosion potential increase with it. Increase of molar ratio cause the znic dissolve resistance increase, and enforce the shield effect of paint. EDS and XRD demonstrated that the main corrosion products during the immersion course is Zn5(OH)8Cl2。...
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