Research On The Technique And Mechanism Of Coloring On Copper And Zinc Alloy

Copper and zinc alloy has favorable physical and mechanical performance, such as good thermal conduction, electric conduction and tactility and so on, and therefore copper and zinc alloy has been widely used in many fields. But it is easy to be oxidated to change its color in the atmosphere. Surface coloring can take the function of increasing erosion resistance and improving decoration.There are two kinds of coloring technique, one is chemical coloring, the other is electrolysis coloring. Chemical coloring is a coloring technique that dyestuff or colored particles are absorbed in the interstice of the film which film adsorbing action is used, or colored particles deposit on the surface through the reaction between copper and zinc alloy. Electrolysis coloring is that a sample is immerged in electrolyte, surface of the sample as a pole is electrolytic treated to be colored.The technique and mechanism of coloring on copper and zinc alloy is researched in the paper. For the purpose of improving the coloring effect, the polishing technique is studied as a key step. The result shows that the polishing surface is applicable to color by chemical polishing than electrochemical polishing. So chemical polishing is used as preparation treating of coloring, and the best parameter is determined. The parameter of coloring process of the copper and zinc alloy is confirmed, for instance electrolyte composition, current density and coloring time, and so on. At the same time, the function of the electrolyte composition is analyzed. The passing model of substance between poles in electrolytic coloring is made. X-ray analysis shows that there is the same substance Cu2O on the surface of the film with different color. The surface pattern is observed through scanning electronic microscope. Cu2O growth is columnar mode, and the growth model of the colored film is established. The research result shows that film color is relate with the thickness of the film. By theoretical calculation, the creation of color is coincident to film interference principle. Investigation considers that there is coherent interface betweenCu2O and Cu-Zn matrix. There is not clear interface between Cu2O and Cu-Zn matrix, which shows the viscidity is well.