Method for preparing salt spray test solution in laboratory
Neutral salt spray test (NSS test) A, covering layer,
a Salt solution is prepared with sodium chloride (chemically pure, analytically pure) and distilled or deionized water, and its concentration is (5% ± 0.1) (mass percentage). The collected liquid after atomization shall not be reused except for the blocking part of the baffle;
b. The pH value of the salt solution before atomization is between 6.5 and 7.2 (35 ± 2 ℃). When preparing a salt solution, you can use a chemically pure dilute hydrochloric acid or sodium hydroxide solution to adjust the PH value, but the concentration must still meet the requirements of point a.
Copper accelerated acetate spray test (CASS test) B. Metal coating,
a. Dissolve sodium chloride in distilled water or deionized water with a concentration of 50 ± 5g / L.
b. Add copper oxide (CuC12 • 2H2O) to the solution a with a concentration of 0.26 ± 0.02g / L (ie 0.205 ± 0.015 g / L anhydrous copper chloride).
Sodium hydroxide adjustment. c. Add an appropriate amount of glacial acetic acid to the a solution to ensure that the pH value of the salt spray collection solution in the test chamber is 3.1 ~ 3.3. If the pH value of the solution before spraying is 3.0 ~ 3.1, the pH value of the collection solution is generally 3.1 ~ Within the scope of 3.3. The pH value of the solution can be measured with an acidity meter, or a precision pH test paper that can be read out with a change of 0.1pH value after calibration by an acidity meter can be used as a daily test. The pH of the solution can be glacial acetic acid or
d. To avoid clogging of the nozzle, the solution must be filtered before use.
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