In coastal areas, because the atmosphere is full of salt spray, it has a strong corrosion effect , and strict requirements are put forward for the protection measures in coastal areas. Therefore, in , people have always used salt spray test as a method of artificially accelerated corrosion test. However, during the salt spray test , due to the influence results obtained in different types of test equipment are quite different, and there are also some controversies. , but is still widely used.
The salt spray test is divided into neutral salt spray test (SS) and acetic acid salt spray test (ASS).
Neutral salt spray is in accordance with GB/T 1771- -91, the concentration of sodium chloride aqueous solution is 50g/L+10g/ L, pH6.5~7.2, and the temperature is 35%C+2°C. The size of the test plate is 150mmx 70mm, and the size of the cross is 150mmX 100mm, and the distance between the scratches and any side should be greater than 20mm. The test panel is inclined at 25°±5°, and placed in the salt spray chamber with the tested side facing up for continuous testing. It is inspected once every 24 hours, and the time for each inspection should not exceed 60 minutes, and the surface of the test panel is not allowed In a dry state. Take it out after the specified time , check and record blistering, rust, adhesion and corrosion spread from scratches. Other standards for neutral salt spray include ISO 7253, ASTM B117, etc.
The acetic acid salt spray test is to improve the corrosion test effect (GB 10125- -88). The pH of the salt spray is 3.1~3.3, and copper chloride is added to the acetic brine to modify the acetic acid salt spray test (CASS) to further speed up the corrosion test. The salt spray test is also combined with the wet and dry test, and is used as a cyclic corrosion test assessment for automotive coatings. For example : at 359C, 5% NaCl solution spray for 4h→60C, RH<35%, dry for 2h→50C, RH>95%, humidity test for 2h, repeat this cycle.