The New Technology Of Stainless Steel Chemical Coloring

Colored stainless steel has beautiful colors and can improve obviously both abrasion resistance and corrosion resistance. So it has been applied more widely in recent years.At present, in the study about stainless steel chemical coloration, the stainless steel material, the coloring liquid composing, the additive multifunction, the dispersant and so on, haven't been improved completely. The two problems, the nonuniformity and the poor color reproducibility of coloring film, seriously restrict colored stainless steel's scale-production.To solve these problems, in the article, first, the method of analyzing Cr⁶⁺,Cr³⁺,Fe³⁺,Ni²⁺ in the aged liquid has been established; secondly, the effects of different stainless steel materials and compositon of basic liquid on coloring have been investigated. The multi-functionalities of additives have been studied and on the base, the uniformity of coloring film has been improved obviously by adding the dispersants. And the new one-step technology of chemical coloring and the firming treatment has been put forward for the first time and the better reappearance of color has been realized.The results show that:(1) Different kinds of stainless steel have different tones of coloring film: the 201# and 202# suit black tone , 304#,316# and 321# suit coloring;(2) In coloring liquid, ZnSO₄ can make the coloring potential stabilize; MnSO₄ can act as an accelerator and a brightener; (NH₄)₆Mo₇O₂₄·4H₂O not only can enhance the brightness, but also can reinforce the wearability of the colored film. The surfactants can improve evidently the uniformity of colored film, also can change coloring speed obviously. The cationic surfactants and the anionic surfactants can make the coloring faster; on the contrary, the nonionic surfactants can slower the coloring.(3) The one-step method of chemical coloring and the firming treating can realize one step way to control the coloration of coloring film, and can replace two-steps traditional technology; current density has very great effect on the abrasion resistance and corrosion resistance of coloring film. With the increasing of the additional current density, the coloring film can be densified, the abrasion resistance and corrosion resistance can be strengthened, but when current density exceeds 0.063mA/cm², stainless steel can not be colored; the current type also has notable effect on the coloring, the coloring liquid with the additional direct current added the nonionic surfactants and the coloring liquid with additional alternating current added the anionic surfactants have good coloring effects.(4)With the reduction-oxidation titrimetry and the spectrophotometer, the concentration of Cr⁶⁺, Cr³⁺, Fe³⁺ and Ni²⁺ ions can be determined. This method is convenient and exact.