Salt Spray Tester (Or salt fog test) is a pretty common corrosion test for various metal spare part.
Application range: usually used to check corrosion resistance of materials and surface coatings. And the materials range cover metallic (although stone, ceramics, and polymers may also be tested) and finished with a surface coating which is intended to provide a degree of corrosion protection to the underlying metal.
Determination: Salt spray testing is an accelerated corrosion test that produces a corrosive attack to coated samples in order to evaluate the suitability of the coating for use as a protective finish. The appearance of corrosion products is evaluated after a pre-determined period of time. Test duration depends on the corrosion resistance of the coating; generally, the more corrosion resistant the coating is, the longer the period of testing before the appearance of corrosion or rust.
Test Standard: ISO 9227, ASTM B117, ASTMG85, ISO:3769, ISO3770, ASTM B268, JIS: D0201, JIS H8502, JIS Z2371
Test Standard Explanation ISO 9227
This standard indicate the test items for neutral salt spray (NSS), acetic acid salt spray (AASS) and copper-accelerated acetic acid salt spray (CASS) tests for assessment of the corrosion resistance of metallic materials, with or without permanent or temporary corrosion protection.
ASTM G85 Acetic Acid Salt Spray Test (non-cyclic)
This can be used to determine the relative resistance to corrosion of decorative chromium plating on steel and zinc based die casting when exposed to an acetic acid salt spray climate at an elevated temperature. This test is also referred to as an ASS test. Test specimens are placed in an enclosed chamber and exposed to a continuous indirect spray of salt water solution, prepared in accordance with the requirements of the test standard and acidified (pH 3.1–3.3) by the addition of acetic acid. This spray is set to fall-out on to the specimens at a rate of 1–2 ml/80 cm2/hour, in a chamber temperature of 35 °C. This climate is maintained under constant steady state conditions. The test duration is variable.
ASTM G85 – Acidified Salt Fog Test (cyclic).
This can be used to test the relative resistance to corrosion of aluminum alloys when exposed to a changing climate of acetic acid salt spray, followed by air drying, followed by high humidity, all at an elevated temperature. This test is also referred to as a MASTMAASIS test. Test specimens are placed in an enclosed chamber, and exposed to a changing climate that comprises the following 3 part repeating cycle. 0.75 hours exposure to a continuous indirect spray of salt water solution, prepared in accordance with the requirements of the test standard and acidified (pH 2.8–3.0) by the addition of acetic acid. This spray is set to fall-out on to the specimens at a rate of 1–2 ml/80 cm2/hour. This is followed by a 2 hour exposure to an air drying (purge) climate. This is followed by 3.25 hours exposure to a high humidity climate which gradually rises to between 65% RH and 95% RH. The entire test cycle is at a constant chamber temperature of 49 °C. The number of cycle repeats and therefore the test duration is variable.
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