Color coated aluminum coils are widely used as metal building materials in coastal, highly corrosive and high-humidity environments. The environment in which they are located is complex and changeable, and various factors such as humidity and temperature may affect their performance. Salt spray testing is a corrosion test for color-coated aluminum coils that accelerates corrosion in an artificially simulated salt spray environment. After a predetermined period of time, the corrosion resistance of the coating in a salty environment is evaluated to predict the service life in a natural environment. Generally, the stronger the corrosion resistance of the coating, the longer the test time before corrosion or rust occurs.
salt spray test method and principle of Colored aluminum Coil
The salt spray test has three types: neutral salt spray test (N SS), acetic acid salt spray test (AA SS) and copper accelerated acetic acid salt spray test (CA SS) which also known as copper chloride acetic acid salt spray test. Among them, the most widely used to evaluate the initial corrosion resistance of color coated aluminum coils is neutral salt spray
The neutral salt spray test of color coated aluminum coil is carried out by special salt spray test chamber. The salt spray test chamber simulates the natural environment of the atmosphere. Providing the specimen with the temperature range, the settling volume of salt mist and the accelerated corrosion environment of the test period specified by salt spray corrosion.
| PH | 5% Sodium Chloride |
|
Temperature |
35℃ |
| Sedimentation rate | 1~2ml/80cm²/h |
Check the phenomenon of destruction in the sample (Including blistering, rust, the decrease of adhesion and spread caused by the corrosion of scratches)use 0-9 nine levels to assess the extent of their damage. When evaluating its foaming grade, rust grade after test, worst value of parallel samples should be taken as test results.
How long does a 24-hour salt spray test equal to the natural environment?
The salt spray test significantly acceleratesthe corrosion process of color-coated aluminum coils by increasing environmental factors such as salt concentration, temperature and humidity. The corrosion phenomenon that originally required several years of exposure to the natural environment to be observed can be observed in just a few days in the salt spray test. Tests have shown that a 24-hour neutral salt spray test is approximately equivalent to 1 year in the natural environment.
Different coatings have different resistance to salt spray corrosion
|
Coating type |
Salt spray test time(h) |
Service life (years) |
|
PE |
≥240 |
≥10 |
|
SMP |
≥480 |
≥20 |
|
HDP |
≥480 |
≥20 |
|
PVDF |
≥720 |
≥30 |