Study On The Surface Color Development Mechanism And Quantitative Characterization Method Of Metal Galvanized Layer

Surface treatment technology can not only improve the corrosion resistance of metal materials,but also enhance the glossiness of the appearance of metal products and improve the decorative effect.At present,there are various appearance colors of metal products on the market,but few color quantitative characterization techniques are applied to metal materials.There is still a lot of room for development in establishing the research direction of color and performance.The development of a reliable appearance evaluation method will help to visualize and surface the performance of the passivation film,greatly reducing the uncertainty of product acceptance and detection.Difficulty,it can also be combined with the results of chromatic aberration research to analyze the influence of the film structure on the color difference of the film.This topic selects a silicate passivation system with simple process,no pollution,and good corrosion resistance,and characterizes the color of the passivation film surface.According to the law of color difference,it combines the microscopic morphology,element distribution and film structure to further The reasons for the chromatic aberration of the surface color were studied.A quality evaluation standard for the surface color of the passivation film has been established,which can be used as a basis for theoretical research on the color difference of the product surface or quality acceptance.Under the premise of ensuring the same pre-treatment,electroplating and post-passivation treatment processes,only the concentration of titanium trichloride in the passivation solution is changed and two sets of passivation solution components are set to explore the effect of titanium on the color development of the passivation film.Among them,the samples of the standard group were passivated with a passivation solution with a concentration of titanium trichloride of 2 ml/L;the samples of the experimental group were passivated with a passivation solution with a concentration of titanium trichloride of 0.2 ml/L.According to the comparative analysis of the SEM morphology,the surface morphology of the experimental group samples has larger-sized hill-shaped protrusions and cracked holes than the standard group samples,which may affect the reflection and interference of light waves on the sample surface and causes the color difference that appears on the surface.Secondly,the backscattered electron map shows that the element distribution on the surface of the sample is very uniform,so it is inferred that the element distribution is not the main reason for the color difference on the surface.According to the analysis of XPS full spectrum and narrow scanning spectrum,it can be seen that the film composition of the passivation film of the standard sample is Zn(OH)₂,Zn O,Zn₄Si₂O₇(OH)₂·2H₂O,TiO₂,Ti(OH)₂,SiO₂,SiO₂ n H₂O and other substances,the passivation film composition of the experimental group samples is Zn O,Zn(OH)₂,Zn₄Si₂O₇(OH)₂·2H₂O,SiO₂ and other substances,the difference is that TiO₂,Ti(OH)₂ and other components are reduced.And take off the crystal water.Therefore,it is inferred that TiO₂,Ti(OH)₂ and other substances are the main substances in the film layer of the standard set of samples,while the titanium element in TiO₂ is prone to dd transition when exposed to light waves.The wavelength range of visible light absorption when the transition occurs determines its surface The complementary color presented further proves that TiO₂ is the main determinant of the bluish color of the film.In summary,the difference in surface morphology cause the difference in the reflection and refraction of the light wave on the surface of the sample,and the difference in the content of the coloring substance TiO₂ in the composition of the film layer together affects the difference in the surface color of the two samples.