Salt spray test method
Neutral Salt Spray Test (NSS)
Neutral salt spray test is a method of accelerated corrosion test, which is carried out in a special salt spray box. Corrosion resistance test for galvanized, cadmium-plated, oxidized and phosphatized coatings on steel parts. .
The salt water prepared by the neutral salt spray test is 5% NaCl solution, the pH is 6.5-7.2, the temperature in the box is 35±2?C, and the relative humidity is above 95%.
Neutral salt spray test spray settling is 1mL ~ 2Ml / 80cm?? h, the collected salt spray NaCl concentration should be 5 ± 1%, PH is 6.5 ~ 7.2, nozzle pressure should be 0.07MPa ~ 0.1 Mpa.
Steps for neutral salt spray test:
(1) Wash the surface of the sample with an organic solvent so that the surface of the sample is free of oil and other materials that are corrosive to the coating.
(2) Place the test piece in a salt spray box. The test piece faces 15 mm to 30 mm from the vertical line.
(3) Conduct salt spray test according to the inspection cycle.
(4) Remove the sample and gently rinse it with running water or gently wipe the surface with a sponge to remove salt deposits, then dry at 80 ° C ~ 100 ° C for about 30 min.
(5) Judging the corrosion grade of the sample.
Acetate spray test (ASS method)
It is mainly used for the corrosion resistance test of decorative coatings such as copper-nickel-chromium or nickel-chromium. The resistance test is prepared by using chemically pure glacial acetic acid in acetic acid salt solution, the pH is 3.0-3.1, and the spray collection pH is 3.2±0.1. The other requirements of the test are the same as those for the neutral salt spray test.
Copper salt accelerated acetate spray test (CASS method)
It is mainly suitable for the corrosion resistance test of decorative coatings such as copper-nickel-chromium or nickel-chromium on steel parts and zinc die-casting parts. It is also suitable for the corrosion resistance test of aluminum and aluminum alloy anodized films.
The preparation method of the test salt solution is as follows: a NaCl solution is prepared according to a neutral salt spray test method. 0.26±0.02 g/L of chemically pure copper chloride (CuCl2?2H2O) is added to the NaCl solution. The pH is adjusted with chemically pure glacial acetic acid. It is 3.0 to 3.1.
The test temperature is 50±1?C, and the spray collection pH is 3.2±0.1. Other requirements are the same as the neutral salt spray test.