Preparation And Properties Of Brass And Carbon Steel Modified With Silane Films

The organic silanization technique is one of the new metal protecting pretreatment in the resent years. It has great advantages such as no pollution, simple to operate and excellent corrosion resistance. Brass and carbon steel are important materials in the economic development, which are widely used in industry and our daily life. However, there is different degree corrosion existing in them in some environments. The purposes of our research are to prepare silane films on brass and carbon steel and to investigate the formation and inhibition mechanism. The main results of this paper can be summarized as the followings:(1) Silane films of3-mercaptopropyltrimethoxysilane (PropS-SH), dodecyltrimethoxy-silane (DTMS), chloropropyl(trimethoxy)silane (CPTMS) and3-aminopropyl(trimethoxy) silane (APS) were formed on the brass surface, and the inhibition efficiency follows the sequ-ence of PropS-SH>CPTMS>DTMS by the electrochemistry test. By means of electro-chemical and contact angle (CA) techniques, the inhibitive action of the PropS-SH and DTMS can be explained by chemisorption which obeys the Langmuir adsorption isotherm. The inhi-bitor mechanism of PropS-SH films was that the Cu-S or Zn-S was formed on the brass surface, providing an excellent combination. Moreover, the corrosion process of brass modified with PropS-SH films was very slow in the3.5%(wt%) NaCl after a long immersed time.(2) The carbon steels were modified with PropS-SH、 vinyltrimethoxysilane (VTMS)、 APS and octyltriethoxysilane (OTES) films, and the inhibition efficiency follows the sequence of PropS-SH>VTMS>APS>OTES. The morphology%element analysis、 structure and corrosion mechanism of PropS-SH silane films were characterized by means of SEM、 EDX and Fourier transform infrared reflection (FT-IR) spectroscopy. The Fe-O-Si was formed on the metal surface, providing an excellent combination. The PropS-SH silane films and the phosphating film were compared by the electrochemical and the CuSO4drips test. The corrosion resistance of silane films was the same with the phosphating film in the3.5%(wt%)NaCl solution, and the time of CUSO4drips test were96s and123s respectively.