Salt Spray Test
Salt spray testing (or salt spray test) is a standardized test and an important tool used to evaluate the corrosion resistance of metals and other materials. This corrosion testing helps manufacturers determine the most suitable materials for their products.
The salt spray test works by creating a controlled atmosphere that mimics corrosive saltwater conditions in a laboratory setting.
A misting chamber is filled with either sodium chloride or magnesium chloride solution which is then sprayed onto the surface being tested.
The length and intensity of exposure are adjustable so the sample can be tested at different levels to simulate different degrees of exposure to corrosive elements found in real-life scenarios. During these tests, samples are regularly monitored over time to measure how well they have held up against corrosion damage.
Salt spray testing is carried out according to ASTM B117, ISO 9227, JIS Z2371, and ASTM G85 standards.
Application of Salt Spray Test
The salt spray test is a popular and reliable method for testing the corrosion resistance of materials. It is used to evaluate a material’s ability to withstand harsh environmental conditions such as moisture, humidity, and temperature.
The test is conducted by exposing the sample material to a salt solution that is sprayed in an enclosed chamber at controlled temperatures and humidity levels. This test helps manufacturers determine which materials are suitable for different applications.
The salt spray test has many practical applications ranging from automotive parts, to electronic components, and medical devices.
Automotive parts such as brakes, gears, and transmission components must be able to withstand high levels of corrosion due to their exposure to road salts and other corrosive elements on roads and highways.
Electronic components such as printed circuit boards also must be tested against salt spray in order to ensure they will operate properly when exposed to salty ocean air or other environmental factors.
Salt Spray Test Equipment
Salt Spray Testing equipment is in the form of a Chamber. Inside the chamber salt water (5% NaCl) solution is sprayed by nozzles on the test specimen using compressed air.
The closed chamber with this condition result in a highly corrsoive enviornment of chloride mist. The test specimens inside the chamber thus will be subjected to strong corrosive conditions.
Salt spray test chambers are available in different sizes and capacity to suit various needs for the testing.
The options for salt spray test solutions depend on the materials being tested. The most common test for steel-based materials is the neutral salt spray test (often abbreviated as NSS), which reflects the fact that this type of test solution is prepared with a neutral pH of 6.5 to 7.2.
Modified tests in salt spray Testing
Modified Salt spray test is mostly carried according to the ASTM G85 standards. In ASTM G85 there are total 5 types of modified test practices from Appendix A1 to A5 as listed below:
- ASTM G85 Appendix A1 – Acetic Acid Salt Spray Test (Non-Cyclic),
- ASTM G85 Annex A2 – Acidified Salt Spray (Cyclic) Test,
- 3. ASTM G85 Appendix A3 – Seawater Acidification Test (Cyclic),
- ASTM G85 Appendix A4 -SO2 Salt spray test (cyclic),
- ASTM G85 Appendix A5 – Salt Mist / Dry Diluted Electrolyte Test (Cyclic).