| Corrosion of iron and steel has always been a difficult problem that puzzles industrial development.It leads to potential safety hazards,and also causes serious waste and economic losses.In order to improve the performance of metal materials such as iron and steel effectively,protect materials from corrosion and prolong their service life,coating protection has become one of the important means.Coating protection plays a protective role by coating a layer of paint on the surface of metals or other materials,forming a protective film with a specific structure on the surface of the substrate,thus enhancing the various durability of the substrate.Super hydrophobic coating has good anticorrosive ability because of its excellent hydrophobic effect,which can effectively isolate the contact between corrosive medium water and base material,and has great prospects in the field of preparing anticorrosive coatings.Inorganic anticorrosive coatings are more environmentally friendly than organic coatings while protecting metals.Therefore,inorganic anticorrosive coatings are also in line with the key research directions of modern anticorrosive coatings.Nano-SiO2 has the characteristics of high temperature resistance,corrosion resistance,friction resistance,abundant raw materials and low cost.Considering the physical and chemical properties and industrial costs,it is a good choice for preparing coatings.Anticorrosive coatings have various functions and wide applications.In this thesis,the protective mechanism of several common coatings for metals such as iron and steel was summarized.Two kinds of normal temperature curing SiO2 composite coatings were prepared and their properties were studied based on the advantages and disadvantages of existing technologies.The main results are presented as follows:1.The nano-SiO2 particles were prepared by simplified Stober method,modified with dodecyl trimethoxysilane(CG-1231)and filled into methyl phenyl silicone resin as filler.Then the nano-SiO2 particles were sprayed on the pretreated steel substrates to obtain organic-inorganic composite coatings.The effects of three common coating methods on the appearance and wettability of the coatings were investigated.It was found that multiple thin spraying was the best choice.Infrared spectroscopy showed that CG-1231 was successfully modified on the surface of silica particles.The effect of SiO2 particle addition on the micro-morphology and wettability of the coating was studied by means of SEM images and contact angle measurement,and the contact angle was up to 157 degrees.The thickness of the sample coating was in the range of 20-40 microns.The acid-alkali corrosion resistance of the coating was excellent,furthermore its alkali corrosion resistance was better than acid corrosion resistance.2.A composite coating was prepared by using high concentration silica sol,methyl triethoxysiloxane,inorganic pigments and additives potassium titanate.Methyl triethoxy siloxane and silica sol were dispersed in ethanol/isopropanol,then fillers,inorganic pigments and other functional additives were added for improving the performance of the coatings,and made the composite coating cured at normal temperature.It is founded that the coating has good stability when the added initial amount of silica sol was 10 g,methyl triethoxy siloxane 5 g,the volume of absolute alcohol and isopropanol(7:3)mixture 10 mL,at pH 5-6 and temperature of 50℃ in the preparation process.No any gel or precipitation was generated.The prepared composite coatings can be cured at room temperature without releasing harmful organic gases during film formation.The thickness of the coating was moderate and the salt spray corrosion resistance was excellent.But the impact resistance was not good enough.When the amount of potassium titanate was 5wt%,the coating has the best stability. |
PDF Full Text Request