The Study Of Normal-temperature Steel Phosphating

Phosphating , as a broad metal surface treatment, may alter the original. Although phosphating in our country has made greatly progress, it still exists many shortcomings, such as high energy consume, low efficiency, serious pollution and unstable performance of phosphating solution etc. Therefore, it is necessary to develop a nice quality phosphating process.The thermodynamics in the phosphating process is discussed. The results show that the phophateration reaction can't take place until the appropriate accelerator was added to the phosphlorization solution.A normal-temperature, extra-thin and corrosion-resistant phosphating solution has been prepared using 5-sulfosalicylic acid dehydrate as additive.The composition of iron phosphating solution for normal-temperature phosphating was researched and the optimum amounts of additives were determined. The outstanding technical properties of the final product are: thin and unbubled coating film, corrosion resistance, less deposit and long protection period for industrial application.The theory of pre-dips is analysis through electrochemistry and SEM, at the same, the temperature and time effect on pre-dip was studied. The results show that the pre-dipped can improve the quality of phosphorization membrane, enhance the ability of anti-corrosion, short the time of phosphorization. The best time on pre-dip is about 50s, the temperature is not higher than 50℃.The normal-temperature darkens- phosphating solution was prepared which through contacting darken solution and phosphating solution. At the same time trough middle-temperature phosphorization, anew kind of film has been got.