ISO 9227 or ISO 9227:2017

The standard ISO 9227 or 9227:2017 is a guideline that describes how to perform the salt spray test, also known as the salt fog test.

The salt spray test is the most widely applied corrosion test for metals, whether or not they have an organic or inorganic coating.

Industry-Standard Corrosion Testing Services according to ISO 9227

By continuously spraying a sodium chloride solution in a climate chamber, corrosion formation is accelerated, and the rust resistance of a material can be checked.

Note: The ISO 9227 standard does not specify a direct relationship between the results of salt spray tests and the expected service life of a material in practice.

Three Variants of ISO 9227

The current ISO 9227 standard has three variants in terms of implementation:

ISO 9227-NSS:
The neutral salt spray test This variant is applied to virtually all metals, with or without a coating. It uses a 5% sodium chloride solution, a temperature of 35°C, and a pH of 6.5 to 7.2.

ISO 9227-ASS:
The acetic acid salt spray test This test is often used for testing decorative coatings of copper-nickel-chrome or nickel-chrome. It is also commonly applied to organic coatings on aluminum (as prescribed in Qualicoat). The difference between ISO 9227-NSS and ASS is that the salt solution in the ASS test is acidified to a pH of 3.1-3.3 by the addition of glacial acetic acid.

ISO 9227-CASS:
The copper-acetic acid salt spray test The CASS variant is used similarly to the ASS variant for testing decorative coatings of copper-nickel-chrome or nickel-chrome and sometimes on coated or anodized aluminum. The implementation is the same as that of the ASS, except with an additional addition of 0.26 grams/liter CuCl2*2H2O and a temperature of 50°C.

Differences with Other Standards

Other standards that describe the neutral salt spray test include ASTM B117 and DIN 50021. These are almost identical in execution to ISO 9227. The difference between ISO 9227 and ASTM B117 is that the samples in ISO 9227 and DIN 50021 are placed at an angle of 15 to 25° instead of the 15 to 30° in ASTM B117.

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