Salt spray test methods and applicable standards

The paint sample is placed in a temperature-controlled salt spray box, and after a certain period of time, the test for evaluating the salt spray corrosion resistance of the paint film is carried out. This is a classic and commonly used test method in corrosion resistance tests, and it is a method to simulate and accelerate the ocean atmosphere. The spray generally uses 3%~5% pure sodium chloride aqueous solution, and the pH value is controlled at 6.5~7.2 neutral salt spray. The x-shaped scratch cut on the substrate with the specified tool is the sample form specified in the coating product standard, and can be evaluated by the corrosion propagation distance (mm) around the scratch. Neutral salt spray test standards include GB/T 1771, ISO 7253, ASTM B117, etc.

The UK developed the "Proheison" test on the basis of the salt spray test, and carried out a simple cycle under two conditions of salt spray and dryness. The cycle is spraying at 25°C for 1 hour, and drying at 35°C for 1 hour (during this period, fresh air is introduced into the salt spray box, so that the visible droplets on the sample plate are completely dried within 3/4). This test uses 0.05% sodium chloride and 0.35% ammonium sulfate, which is suitable for industrial anti-corrosion coatings.