The Preparation And Performance Research Of Silane Treatment Fluid As A Substitute For Car Coating Phosphating

Traditional automobile coating process is:first, degreasing and surface conditioning; second, phosphating; third, electrophoresis and painting. Phosphating is a key technology. It is used for surface pretreatment before automobile coating. Phosphating process has many advantages, but there are also its own disadvantages which are unable to overcome. Such as it will produce a large number of harmful gases, phosphate slag and waste water, which polluted the environment seriously. With the enhancement of people’s environental protection consciousness, these disadvantages of traditional phosphating restricts its further development seriously. Improvement direction of the car coating pretreatment process at present is to use silane coupling agent to coat film instead of the phosphating film, namely a new type of silicon alkylation treatment technology.The research purpose and meaning of this topic is:through the experiment, new silane treatment fluid is prepared. It is a technological process which is used for silane coupling agent handling, thus instead of phosphating treatment.This topic used the steel substrate as experimental material. First, it was hydrolysis research of siliane. Factors and levels which influenced silane treatment fluid hydrolysis were tested by using the electric conductivity method. Then the optimum hrdrolysis conditions of two kinds of silane were obtained through the single factor experiment and orthogonal experiment methods. The next step was the exploration of silane film forming factors and performance characterization. The optimum film-forming process of two kinds of silane were obtained through the orthogonal experiment method. Single-layer silane films were prepared. Then a series of performance characterizations were made, such as measuring film thickness, electrochemical polarization curves and salt spray test. Finally, it was the compounding of two kinds of silane solutions and performance research. The best mix proportion of two kinds of silane and the optimum film-forming process of combination solution were obtained. The composite silane film was prepared. Then a series of performance characterizations were made.According to the experiment result, single silane films protected steel plates not long time, corrosion resistance was poor, and the silane film was very thin, film thickness was around 4μm. The composite silane film thickness was around 8 μm. Compared with single-layer silane film, film thickness has improved greatly, corrosion resistance has also been enhanced greatly. It further illustrated that the composite silane film was dense and uniform, and had a better performance.Through consulting relevant literature and datum and combining with industrial production, the ideal silane thickness is between 8μm and 10μm. However, dense uniform and a better performance composite silane film thickness is around 8μm. There is a certain distance compared with the ideal silane film. So making the silane film doping and modification, in order to further improve the silane film thickness and enhance its corrosion resistance. It is the focus of the research in the future. It remains to be further explored.