Salt Spray Test
The salt spray test is an accelerated corrosion test used to measure the comparative corrosion resistance of materials exposed to a salt spray or salt fog at high temperature.
This corrosion test is intended to provide corrosion resistance information on metals and coated metals. With visual inspection following this test the suitability of coatings, paints and metals to resist corrosion or exposure to marine environments can be determined.
Three types of laboratory simulating salt spray: NSS, ASS and CASS.
(1) NSS (Neutral Salt Spray) is the earliest test method and widely used recently. The salt solution concentration shall be 5% and the pH range is between 6.5 and 7.2, the test temperature of the salt spray chamber shall be maintained at 35℃, also sedimentation of salt solution shall be 1-2ml/80cm2/h.
(2)ASS (Acetic Acid-Salt Spray) is developed based on NSS. ASS adds some glacial acetic acid to 5% Nacl solution, to get a pH of 3, the solution becomes acid so the fog. Finally, the acidic solution can accelerate the corrosion rate to 3 times of NSS. 3)CASS (Copper-Accelerated Acetic Acid-Salt Spray) is a new method of accelerated salt spray test. The temperature in chamber is 50℃, the solution contacts some copper dichloride, so it can get a intense corrosion. The corrosion rate can be accelerated to about 8 times of NSS.
Test standard for reference
GB/T 2423.17，IEC60068-2-11,ISO4628-3, ASTM B117, JIS-Z2371, JIS-G3141, GJB 150.1, MIL-STD-810F, MIL-STD-883E etc