Synthesis Of Silane Coupling Agent Si-69and Application Research In The Aluminum Alloy Surface Treatment

The fastest growing silicon market of the world is China, and the silane coupling agent Si-69is a very important species, its scale of production and sales are the forefront among so many coupling agents. In recent years, the metal surface anti-corrosion treatment technology by organic silylation demonstrated sample process, non-toxic, pollution-free, wide range applications, excellent corrosion resistance and other advantages, making the using of Si-69has become a hot spot in metal surface treatment.This paper reviewed the existing methods of synthesis of Si-69at home and adroard, and the production technology of Si-69was improved for the current synthesis of the many drawbacks. Sulfur powder,chloropropyltriethoxysilane and nine water-sodium sulfide which is cheap and available were used as raw material and toluene was used as the solvent to synthesis Si-69. The optimum process condition was summarized as follows:the molar ratio of sulfur powder and nine water-sodium sulfide was3.0:1.0; the molar ratio of toluene and nine water-sodium sulfide was36:1; the molar ratio of chloropropyltriethoxysilane and polysulfide was2.1:1.0; the molar ratio of absolute alcohol and polysulfide was8.0:1.0; the synthesis temperature was80℃; the synthesis time was3.5h; the activated carbon dosage was5%of weight of the product; the decolorization temperature was60℃for10min. The appearance of obtained product was light yellow and it also could be stored for a considerable period of time. The yield was95.43%and the sulfur content was up to23.21%.Also, the surface silylation anti-corrosion treatment process in aluminum alloy2024was systematically studied. The hydrolysis conditions of Si-69were probed by the orthogonal design. And the influence of film-forming factors on the corrosion resistance of aluminum2024was also studied. The best anti-corrosion technology was systematically identified as follows:each100ml solution contained V乙醇: V水=85ml:15ml; the dosage of VSi-69was5%of the total volum of the solvent; hydrolysis pH was6, hydrolysis time was about96h; film-forming temperature was200℃; film-forming time was above90min.The electrochemical test and neutral salt spray test showed that the silane films effectively prevented the cathode active sites reduction reaction which the corrosion particles participated in. And the corrosion resistance of aluminum2024was greatly improved.