Preparation And Properties Of Silane Self Assembly Film On 6061 Aluminum Alloy Surface

Aluminum alloy is one of the most commonly used metal structure materials. It has been gradually replacing the copper material in the evaporator of refrigerator. But the material is prone to local corrosion, resulting in the failure of refrigeration equipment.Therefore, it is necessary to develop a kind of simple process of excellent anti-corrosion. According to the characteristics and requirements of aluminum material for evaporator, this paper discusses three key scientific problems:Firstly, preparation parameters of SAMs were optimized;. Secondly, study on the structure and corrosion resistance of SAMs. Finaly, The self assembly behavior of SAMs on aluminum alloy surface was studied, and the mechanism of chemical bond formation between self-assembled atom and metal surface was revealed by molecular dynamics simulation method.The dodecafluoroheptyl-propyl-trimethoxysilane (G502) and the bis-(y-triethoxysilylpropyl)-tetrasulfide (BTESPT) SAMs were successfully prepared. The effects of self-assembly concentration, self-assembly time, curing temperature and curing time on SAMs were investigated. The optimized process parameters for the preparation of SAMs were obtained. On the basis of single SAMs, the self assembly composite membranes were prepared by doping and compounding method.Secondly, the morphology, composition, structure and corrosion resistance of G502 and BTESPT SAMs were studied by SEM, surface scan, XPS, salt spray corrosion test and corrosion electrochemical performance test. The results show that the two self-assembly membranes have good coverage and flatness; Self assembled molecular elements distribute uniformly on the surface. Between BTESPT and metal atoms, Al-O-Si, R-S-OR and Al-O-OH chemical bonds are formed by relying on O, S and H atoms with metals. Between G502 and metal atoms, Al-O-Si bonds are formed only by O and metals. The corrosion resistance of BTESPT SAMs was three times higher than that of G502 SAMs, and the corrosion resistance increased 15%. And the BTESPT self assembled membrane remained intact after 120 hours by neutral salt spray corrosion test, which exceeded the existing technical standards. Corrosion electrochemical performance tests showed that the electrochemical behavior of SAMs was mainly controlled by electrochemical anodic polarization. Another corrosion resistance of self assembly composite membranes showed that their corrosion resistances were not obvious.Finally, the adsorption mechanism of G502 and BTESPT self-assembled molecules on Al (110) surface was studied by molecular dynamics simulation. Results showed that:Chemical bonds depend on the characteristic atoms and Al atoms on G502 and BTESPT SAMs respectively. Between BTESPT and metal atoms, Al-O-Si, R-S-OR and Al-O-OH chemical bonds are formed by relying on O, S and H atoms with metals. Between G502 and metal atoms. Al-O-Si bonds are formed only by O and metals. It is concluded that BTESPT could form higher coverage and better compactness a molecular adsorption membrane than G502 on the metal surface. The self assembled membranes effectively prevent the corrosive medium from directly contacting with the metal surface. So the SAMs improved the corrosion resistance of aluminum alloy.In a generally, the corrosion resistance of BTESTP self assembly membrane was better than that of G502. Therefore, in order to improve the service life of the evaporator, BTESPT is more suitable for the surface treatment of aluminum in the evaporator of the refrigerator.