Research On Silane Coupling Agents (SCA) For Heat Resistant Ogannisilicone Coating

Domestic high temperature and anticorrosive coatings are mainly imported for the coatings applied to pressure reactor vessel in the nuclear power station have not met some long-term requirements such as heat resistance, radiation resistance and adhesion. A kind of high-temperature prevention anticorrosive organic-silicone primer was developed through well selection of resin and pigments. Organic silane coupling agents (SCA) were widely utilized in coating system as additive, surface modification of pigments and surface treatment of metal substrate.In order to improve the compatibility between pigments and resin and make full use of synergism among different fillers, modification process by SCA of aluminum triphosphate and zinc phosphate powder and their dispersion in coating were mainly discussed. The preferable modification process of aluminum triphosphate was obtained at70℃for3h with the dosages of aminopropyltriethoxylsilane (DB550)4.0%(wt%), and that for zinc phosphate was at50℃for2h with the dosages of phenylaminotrimethoxylsilane (DB073)2.0%(wt%), resulted from orthogonal tests. Infra-red spectrum analysis showed the hydroxyl group absorbed was replaced by SCA. The results of the mechanic properties and scanning electron microscope (SEM) suggested that the modified pigments acted excellent compatibility with silicone resin showed well synergism.Methyl phenyl silicone resin was serviced as film-forming substance. Thermogravimetry (TG), SEM and electrochemical impedance spectroscopy (EIS) were employed to analyze the heat resistance, surface topography and anti-permeability of coating, respectively. Immersion test and neutral salt spray test were carried on to study the anti-corrosion property. It is be conclude that the coating performed well in mechanic properties and heat resistance, which can be used at320℃for a long time. Corrosion potential Ecorr was positively shitted suggested perfect anti-corrosion performance. EIS indicated excellent anti-permeability.To improve adhesion, application for SCA in the metal pretreatment was discussed. The hydrolysis process of mercaptopropyltriethoxysilane (MPTES, DB580), the properties of as-prepared silane film, and therefore, the effect on the performance of coating were studied. The preferable hydrolysis process of MPTES was hydrolyzed at55℃for8～10h, pH6-7, with the concentration5.0%using alcohol-water mixture solvent (2:1, V%), resulted from orthogonal tests. The better mechanic properties of coating with MPTES film were possessed when the thickness of the continuous oil-like membrane was less than5μ m. IR and IR-RA indicated that the chemical Me-O-Si bone was form at the interface. TG analysis showed that the thermal decomposition temperature of coating with MPTES film was increased by38℃. EIS suggested anti-permeability and anti-corrosion properties were greater improved.