Neutral salt spray test is a method of accelerated corrosion test, which is carried out in a special salt spray box It is applicable to the corrosion resistance inspection of zinc plating, cadmium plating, oxidation and phosphating coatings on iron and steel parts
The brine prepared for neutral salt spray test is 5% NaCl solution, pH is 6.5 ~ 7.2, and the temperature in the box is 35 ± 2? C. The relative humidity is above 95%
The spray deposition of neutral salt spray test is 1mL ~ 2Ml/80cm? h. The NaCl concentration of the collected salt spray shall be 5 ± 1%, the pH shall be 6.5 ~ 7.2, and the nozzle pressure shall be 0.07MPa ~ 0.1 MPa
Steps of neutral salt spray test
(1) Clean the sample surface with organic solvent to make the sample surface free of oil stain and other articles corrosive to the coating
(2) Place the test piece in the salt spray box, with the test surface of the test piece facing upward and 15 ° to the vertical line 30?.
(3) Carry out salt spray test according to the inspection cycle
(4) Take out the sample, gently wash it with flowing water or gently wipe the surface with sponge with water to remove salt deposits, and then wash it at 80? C～ 100? C dry for about 30min
(5) Evaluate the corrosion grade of the sample
Acetate spray test (ASS method)
It is mainly applicable to the corrosion resistance test of decorative coatings such as Cu Ni Cr or Ni Cr. The resistance test is made by acetic acid spray with chemical pure glacial acetic acid. The PH is 3 to 3.1, and the PH of spray collection fluid is 3.2 + 0.1.. Other requirements of the test are the same as the neutral salt spray test method
Copper salt accelerated acetate spray test (CASS method)
It is mainly applicable to the corrosion resistance test of decorative coatings such as copper nickel chromium or nickel chromium on iron and steel parts and zinc die castings, as well as the corrosion resistance test of anodic oxide film of aluminum and aluminum alloy
The preparation method of salt solution for the test is as follows: prepare NaCl solution according to the neutral salt spray test method Add 0.26 ± 0.02g/l chemically pure copper chloride (CuCl2? 2H2O) to NaCl solution Adjust the pH to 3.0 ~ 3.1 with chemical pure glacial acetic acid
The test temperature is 50 ± 1? C, the PH of spray collection solution is 3.2 + 0.1, and the other requirements are the same as neutral salt spray test.
