Research Of Silane Treatment And Coating Technology On The Surface Of Steel Surface

With the international demand for energy saving and environmental protection in the automotive coating process, "green, environmental protection, low carbon,simplification" has become the theme and direction of the development of automobile coating production, the traditional pollution of the environment of traditional phosphating technology Gradually replaced by green and non-phosphating treatment technology to silane, zirconium salt treatment for the metal surface treatment technology compact production process has become the mainstream of today’s automotive coating process, but also China’s automotive coating industry’s main direction of development.This major change in the pretreatment of the body before painting and electrophoresis primer and other aspects of the higher requirements.In this paper, two kinds of silane, such as dimethyldimethoxysilane (MSDS) and vinyltriethoxysilane ( VS ) , which are common and widely used are selected. The optimum conditions for hydrolysis and optimum film-forming conditions are explored.The properties of silane films were optimized and optimized. The results showed that MSDS was dried at a concentration of 2 % silane, hydrolysis temperature 30 ℃, ethanol content 20%, pH = 4.5 and hydrolysis time 25 min. The temperature is 40 ℃, drying time is 2 min, the film formation effect is the best. The hydrolysis temperature was 30 ℃, the ethanol content was 30 %, the pH value was 6, and the hydrolysis time was 30 min. The effect of the film formation was 30 s , The drying temperature is 50 ℃, the drying time is 2 min. The average thickness of the obtained MSDS film and the VS film was 4.2 μm and 4.9 μm, respectively. The average thickness of the composite silane film is between 6 and 7μm, and the combination of the two silane films improves the corrosion resistance of the silane film to a certain extent. Among them, the reaction effect of MSDS : VS = 3 : 2 was the best, and the hydrolysis temperature was 30 ℃, the hydrolysis time was 30 min, the pH was 5, Soaking time is 30 s, the drying temperature is 45 ℃ under the conditions of hydrolysis, film effect is the best.In the process of cathodic electrodeposition coating, the control voltage gradually increased from 0 V to 300 V, and the bath was sieved into the steel plate of the silane treatment solution by the following steps : the emulsion : water = 1.0 : 4.0 : 5.0 was prepared and stirred for 2 h. Remove the solution directly placed in the bath for 120 s electrophoresis, and then took out with a slow flow of water rinse off the surface adhesion of a layer of paint, dry at room temperature, into the vacuum oven 170 ℃baking 20 min, the paint Membrane through the cross-linking curing to achieve the best performance, remove and cool to room temperature can be made to smooth the film. The thickness of the film obtained by electrophoresis after pretreatment of MSDS, VS and both of the silane hydrolyzate is between 15 and 20 μm, and the appearance of the film is smooth, The adhesion reached a level above, corrosion in the salt spray box more than 1000 h after the single side of the fork erosion≤2 mm, the overall quality of the compact process to achieve the required level.