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The salt spray tester can measure inorganic or organic coatings of ferrous or non-ferrous metals, such as plating, anodization, chemical conversion, paint, and other surface treatments. The method for evaluating the corrosion resistance of the surface treatment is preferably exposed to the same environment as the use condition. However, the disadvantage of the actual exposure test is that the test period is long, the change in the environment is considered to be many factors, and the reproducibility of the test is limited. In order to require its high degree of reproducibility and in order to ensure that all laboratories in the world have the same conditions and results, their test conditions and methods are uniformly regulated. At present, the corrosion analysis is similar to salt fog, so how to accurately and effectively control the salt spray conditions, so as to improve the reproducibility for analysis of corrosion resistance and reliability.
Before the salt spray test, a good salt spray test solution was prepared, and the reagent and Nacl2 were dissolved in distilled water (or water with a total dissolved solid content of not more than about 200 ppm), and a test solution with a concentration of 51% was prepared. The test solution was sprayed at 35°C. After spraying, the pH of the network solution should be 6.5-7.3. Before spraying, this test solution cannot contain floating matter.
Note (1): Nacl2 is less than copper-nickel containing impurities. The content of dianhuana in solids is less than 0.1%. Since the impurities contain presumably cortisol, the total impurity content must be less than 0.3%.
(2): The specific gravity of the test liquid should be 1.0258~1.0402 at 33~35°C, and 1.0292~1.0443 at 25°C. The concentration of this test solution can also be determined with silver nitrate droplets or other methods.
(3): The test solution must be adjusted with reagent-grade hydrochloric acid or dilute sodium hydroxide solution to adjust the pH. • Use a pH meter or other reliable method to measure the pH. • Since the test solution contains carbon dioxide in the water, the solubility of carbon dioxide in the water As the temperature changes, the pH of the solution is affected, so it is necessary to be vigilant to control the pH. • The pH can be adjusted according to any of the following methods:
1 Prepare the test solution at room temperature. • Spray at 35°C. Raise the pH by allowing part of the carbon dioxide to escape the solution due to the temperature increase. Therefore, when the test solution is prepared at room temperature • The pH value should be adjusted within 6.5. • Before the pH of the network solution can be adjusted between 6.5 and 7.2. 2 pH adjustment, the test solution is allowed to boil and then cooled to 35°C or maintained at 35°C. °C temperature 48 hours. When Yunyun Mediation's pH is sprayed at 35°C, it will not produce too much change.
3 Heat the water to 35°C or more to remove dissolved carbon dioxide. Then adjust the test solution and adjust the pH value. When nebulosity is sprayed at 35°C, the mediated pH value will not produce too much change.
(4) In order to stop the spray nozzle from closing, the test solution shall be filtered or vigilantly raked into a person's saline bucket, or be fitted with a glass sieve filter at the front end of the spray suction pipe.
Operation: How to prepare the test solution when salt spray test?