Preparation And Protection Of Silane Hybrid Film On Alloy

Due to its excellent physical and chemical properties, aluminum and its alloys have been applied in many fields. At present, a simple and effective method of aluminum alloy protection is very important. Silane hybrid film combines the excellent properties of organic and inorganic films, which renders it promising materials for coating. In this paper, aluminum alloy (AA5052) was chosen to be substrate Hexadecyltrimethoxy-silane (HDTMS) was chosen to be organic precursor, and nano-SiO₂ to be as inorganic precursor. Organic/inorganic hybrid films were prepared by sol-gel method by adding nano-SiO₂ into HDTMS solution. The various properties of the coating were characterized. Modified electrodes measurements were carried out by polarization curves, IR spectra, scanning electron microscopy (SEM) and contact angle. The conditions for preparation hybrid film were obtained from the results. The protection of HDTMS films was tested by polarization curves and seawater experiments. The result showed that the coating exhibited excellent anticorrosion properties. The results of experiments listed as follows:1. The surface roughness of alloys increased after pretreatment by scanning electron microscopy (SEM). The results of IR spectra showed the formation of HDTMS nano-film. The contact angles were measured to be 158°by contact angle meter.2. The results showed the conditions for preparing hybrid film: aluminum alloy was immersed in 3%HDTMS solution for 20min and cured at 160℃. The silane hybrid films exhibited excellent anticorrosion properties as additives amount of nano-SiO₂. But the performance was weakened when additives are more than 15 ppm.3. The protection of silane hybrid film was evaluated by electrochemical measurements and seawater experiments. The potential of silane hybrid film increased and the current reduced than HDTMS film. The protection efficiency of silane hybrid film was 92.7%. The alloy was immersed in 3.5% NaCl solution for 10days. The surface of alloy had not any corrosion, while untreated alloy had serious corrosion.