Introduction:
　　In the field of aluminum protection, passivation anti-corrosion process has become a key technology to extend the service life of aluminum and broaden the application range because of its excellent anti-corrosion performance. The stability and shelf life of passivation solution are important indexes that affect passivation effect and production cost. In the form of academic dialogue, the stability and shelf life of passivation solution are deeply discussed, and relevant improvement measures are proposed.
　　Dialogue 1: Stability of passivation solution
　　Scholar A: The stability of the passivation solution is one of the key factors affecting the passivation effect. What factors do you think affect the stability of passivation solution?
　　Scholar B: The stability of passivation solution is affected by many factors, mainly including chemical composition ratio, pH value fluctuation, temperature change and impurity mixing.
　　Scholar A: Can you elaborate on the specific effects of these factors?
　　Scholar B: Of course. First, the precise control of the chemical composition ratio is essential. For example, if the proportion of phosphate in the passivation liquid is lower than the lower limit of the standard range, a complete and dense passivation film cannot be formed, resulting in the corrosion resistance of aluminum can only reach 40%-50% of the normal level. In addition, the improper allocation of additives, such as excessive corrosion inhibitors, will significantly reduce the passivation reaction speed and extend the passivation process time.
　　Scholar A: What is the effect of pH fluctuation on the stability of passivation solution?
　　Scholar B: The fluctuation of pH value will directly affect the stability of passivation solution and passivation reaction rate. Experimental data show that the optimal pH range of aluminum passivation solution is generally between 4.5-5.5. When pH value is higher than 6.0, the growth rate of passivation film will be reduced by about 30%, and the film becomes loose and porous. When the pH value is lower than 4.0, some of the active ingredients in the passivation solution will decompose, resulting in the failure of the passivation solution.
　　Scholar A: What is the effect of temperature change on the stability of passivation solution?
　　Scholar B: The passivation process can be accelerated by increasing temperature within a certain range. For example, when the temperature is increased from 25 ° C to 35 ° C, the passivation reaction rate can be increased by about 40%. However, when the temperature exceeds 45 ° C, some components in the passivation solution may occur thermal decomposition, and the decomposition rate of the active components can reach 15%-20% within a week, reducing the stability of the passivation solution.
　　Scholar A: What is the effect of impurity mixing on the stability of passivation solution?
　　Scholar B: Metal impurities, dust, water, etc. mixed into the passivation liquid will cause adverse chemical reactions. For example, after iron ions are mixed, the decomposition rate of passivation liquid will be accelerated by 2-3 times; The mixture of water will dilute the concentration of the passivation liquid and change its chemical composition ratio, resulting in unstable passivation effect.
　　Dialog 2: Shelf life of passivation solution
　　Scholar A: The shelf life of passivation solution is another important indicator. What is the difference in shelf life between different types of passivation fluids?
　　Scholar B: Because of its relatively stable chemical properties, the traditional chrome-containing passivation solution can generally have a shelf life of 18-24 months under good sealing and suitable storage conditions. However, the use of chromium-containing elements has been gradually restricted due to their harm to the environment.
　　Scholar A: What is the shelf life of chromium-free passivation solution?
　　Scholar B: Chromium-free passivation solution is the current development trend, and its shelf life is mostly 12-18 months. For example, a brand of organosilicon-based chromium-free passivation solution has a shelf life of 15 months under storage conditions.
　　Scholar A: What are the shelf-life characteristics of the new compound passivation solution?
　　Scholar B: The new composite passivation solution adopts advanced corrosion inhibition technology and stability system, and some high-performance composite passivation solutions can reach 24-36 months of shelf life. However, the production cost of such passivation fluids is usually high, and the technical threshold is relatively high.
　　Scholar A: What are the factors that affect the shelf life of passivation solution?
　　Scholar B: Storage conditions and packaging materials are the main factors affecting the shelf life of passivation solution. The high temperature environment will accelerate the decomposition of the chemical components in the passivation solution, and when the storage temperature exceeds 35 ° C, the shelf life of the passivation solution may be shortened by 30%-50%. High humidity environment can easily lead to water mixing with passivation solution, causing component dilution and hydrolysis reaction. Light, especially ultraviolet light, can trigger photochemical reactions of certain chemicals and destroy the stability of the passivation solution.
　　Scholar A: What is the effect of packaging materials on the shelf life of passivation solution?
　　Scholar B: The packaging material of passivation solution should have good corrosion resistance and sealing property. The use of high-quality corrosion-resistant plastic or metal lined packaging can effectively extend the shelf life of passivation solution. For example, the use of fluorine plastic lined metal drum packaging, can extend the shelf life of 1-2 months.
　　Conclusion:
　　In aluminum passivation anti-rust process, the stability and shelf life of passivation solution are interrelated and far-reaching factors. Through strict control of the production process, the use of high-quality raw materials, reasonable storage and maintenance, the stability of the passivation liquid can be effectively improved and its shelf life can be extended, so as to ensure the efficient implementation of the passivation process, provide reliable protection for aluminum, and promote its wide application in various fields.