ISO 9227 is a European standard that deals with salt spray testing. This is a method to test whether the quality of a metallic material can be maintained without or with corrosion protection. There are various factors that can influence the progression of corrosion. They have very different effects on the formation of protective layers.
By choosing salt spray fog testing as a corrosion test, it is possible to determine very quickly whether weak spots, pores or damage are present in organic coatings and inorganic coatings.
Samples are taken for quality control. These samples are provided with the same coating or with the same coating. This is an important prerequisite, because salt spray testing is only suitable if the individual coatings are of the same type.
ISO 9227 clearly specifies which equipment, which reagents and which procedures are to be used in salt spray testing. A distinction can be made between a neutral salt spray test, an acetic acid salt spray test and a copper-coated acetic acid salt spray test. The ISO 9227 standard describes the procedures used to evaluate corrosivity in the test chamber.
In addition, ISO 9227 specifies the dimensions of specimens to be used for certain products. Other important points of ISO 9227 are the duration of exposure and the interpretation of results, which is defined in product specifications. The salt spray tests are used to determine whether pores or other weak spots are present.
Neutral salt spray testing is performed for with metals and alloys using a 5% sodium chloride solution with a pH between 6.5 and 7.2.
In acetic acid salt spray testing, glacial acetic acid is added to the 5% sodium chloride solution. The pH value is between 3.1 and 3.3. According to ISO 9227, the test takes place under precisely defined conditions. Acetic acid salt spray testing is used to test decorative coatings of copper + nickel + chromium or of nickel + chromium.
In the copper-coated acetic acid salt spray test, copper chloride and glacial acetic acid are added to the 5% sodium chloride solution. The pH value is between 3.1 and 3.3. Decorative coatings of copper + nickel + chromium or nickel + chromium are tested under specified conditions.