Preparation And Characterization Of Triazinedithiol And Organosilane Composite Polymeric Nano-film On Aluminum Alloy Surface

The triazinedithiol polymeric nano-film can inhibit metallic corrosion, and the close-packed polymeric thin films have a good future in metal protection. Therefore, triazinedithiol is expected to replace chromate-based treatment effectively, which is also harmless. Since K. Mori's group first prepared triazinedithiol polymeric nano-film by electrochemical methods, the further modification of this type of polymeric nanofilm has not been reported so far.Due to the low cost, light weight, high mechanical intensity, easy modeling and good recycling, aluminum and its alloys have been applied in many fields, such as electronic industry and aerospace. However, their expanding application has been limited due to poor corrosion resistance, and sometimes additional protection is required. Thus, many researches have been carried out to study environmental friendly system.In the study, the composite polymeric nano-film (CPDB) are obtained successfully by a novel surface modification technique: polymeric nano-film (PDB) are prepared by electrochemical polymerization of 6-N,N-dibutylamino-1,3,5-triazine-2,4-dithiol monosodium (DBN) on AA5052 surface. Then the PDB film is treated by silanization of hexadecyltrimethoxysilane to fabricate the composite polymeric nano-film (CPDB). The results are as follows:(1) The fourier transform infrared (FT-IR) spectra and cyclic voltammetry curves were carried out to investigate the optimal supporting electrolyte and potential for the electrochemical polymerization of DBN. The results indicated that NaNO2 is the ideal supporting electrolyte and the optimal potential is 3.8V for electrochemical polymerization of DBN on AA5052 surface.(2) The cyclic voltammetry curves were used to study the electrochemical reaction and film growth process of PDB on AA5052 surface. The formation mechanism and the optimal conditions for preparation of CPDB film were also analyzed. The film was characterized by means of X-ray photoelectron spectroscopy, FT-IR spectrometer, SEM and contact angle. The results showed that the contact angle of AA5052 surface covered by PDB film was up to 124.3°compared to that of blank AA5052 (89.9°) , and the contact angle of the sample covered by CPDB film's was up to 135.8°. From the results of SEM and XPS, homogeneous and compact composite polymeric nano-films were obtained.(3) The salt spray test and potentiodynamic polarization test results showed that the protection efficiency is 77.5% for PDB covered surface, and is as high as 94.3% for CPDB covered surface. The obtained CPDB film showed an excellent inhibitive effect to protect aluminum alloy from corrosion.