Method for analyzing citric acid in stainless steel electrolytic coloring liquid

Abstract

The invention discloses a method for analyzing citric acid in stainless steel electrolytic coloring liquid. The method comprises the following steps: by selecting bromothymol blue as an indicator, analyzing the content of citric acid in the stainless steel electrolytic coloring liquid by adopting an acid base titration method, wherein the titration is ended when the color is changed from colorless to pure green. The stainless steel electrolytic coloring liquid comprises the following main components: 60g / L of sodium molybdate, 30g / L of citric acid, 3g / L of manganese sulfate, 25g / L of zinc sulfate and 15g / L of ammonium sulfate. According to the stainless steel electrolytic coloring liquid, a color film layer is formed on the stainless steel surface, so that the attractive appearance and wear resistance of stainless steel are enhanced, the content of citric acid changes along with the production, and the color of the film layer is influenced. The method disclosed by the invention has the advantages that the analytical error is less than 5 percent, and the measurement of citric acid in the stainless steel electrolytic coloring liquid in enterprises is met; and moreover, the analysis method is easy to operate, the practicability is high, the accuracy rate is high, the reproducibility is high, the error is small and the analysis method is easy to master.

Description

technical field [0001] The invention belongs to the fields of material science and analytical chemistry, and relates to a method for quantitatively analyzing citric acid in stainless steel electrolytic coloring liquid, in particular to an analysis method for citric acid in stainless steel electrolytic coloring liquid. Background technique [0002] Stainless steel has excellent mechanical properties and chemical stability, and is widely used in marine, petroleum, chemical, construction and other aspects. higher. Colored stainless steel not only maintains the original excellent performance of stainless steel materials, but also adds fun to people's life with beautiful color appearance. There are many types of technologies for forming color films on the surface of stainless steel, which can be roughly divided into 6 categories: electrochemical coloring, chemical coloring, high temperature oxidation, electroplating, laser surface treatment and ion deposition. Among them, the ap...

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Problems solved by technology

There are many types of technologies for forming color films on the surface of stainless steel, which can be roughly divided into 6 categories: electrochemical coloring, chemical coloring, high temperature oxidation, electroplating, laser surface treatment and ion deposition. Among them, the application of electrochemical coloring The most extensive, domestic and foreign scientific research workers have conducted many pioneering researches on the electrochemical coloring process of colored stainless steel, but the reproducibility and uniformity of the color of the colored film have not been completely resolved, mainly because the components of the stainless steel electrolytic coloring solution will continue to change. Consumption, especially the consumption of citric acid is faster, making the bath not stable enough, and making the final coloring effect not good

[0003] Although the existing citric acid analysis method is very mature, that is, the acid-base titration method, the standard sodium hydroxide solution is used for titration, and the phenolphthalein indicator is used to judge the end point, and the solution changes from colorless to red as the end point. The analysis of citric acid in the coloring solution is inaccurate, the error is as high as 42.20%, mainly because the bath solution contains NH 4+ , while NH 4+ It will be hydrolyzed to make the solution acidic, which affects the analysis of citric acid, making this analysis method unable to accurately analyze the content of citric acid in stainless steel electrolytic coloring solution

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