EN IEC 60068-2-52 Environmental Tests - Part 2-52: Tests - Test Kb: Salt Mist, Cyclic (Sodium Chloride Solution)

Produced using salt, metallic and non-metallic materials in the “EN IEC 60068-2-52 Environmental tests - Part 2-52: Tests - Test Kb: Salt fog, cyclic (sodium chloride solution)” standard developed by the International Electrotechnical Commission (IEC). A method is described for cyclic salt mist testing applied to components or equipment designed to resist a salt-laden atmosphere because it may degrade the performance of the parts.

The latest update to this standard contains significant technical changes. For example, the entire content has been harmonized as much as possible with the standard “ISO 9227 Corrosion tests in artificial atmospheres - Salt spray tests” published by the International Organization for Standardization (ISO). In addition, the scope was simplified, the general definition of the test was changed, a dry room was added to the test equipment, the significance levels were changed according to the test methods, and test methods 7 and 8 were added. Meanwhile, the description of each test method is included in the standard annex (Annex B).

Salt spray tests are particularly useful in detecting discontinuities such as pores and other defects in certain metallic, organic, anodic oxide and conversion coatings.

These tests are particularly valid for:

• Metals and their alloys
• Metallic coatings (anodic and cathodic)
• Transformation skins
• Anodic oxide coatings
• Organic coatings on metallic materials

Salt spray methods are all suitable for checking that the quality of a metallic material is maintained, with or without corrosion protection. They are not intended to be used in comparative tests to rank different materials against each other based on corrosion resistance or to predict the long-term corrosion resistance of the material under test.

The EN IEC 60068-2-52 standard consists of cyclic test conditions of salt fog, dry condition, moist condition and standard atmosphere. The effect of each test condition is as follows. By the way, salt fog is also called salt spray. Test samples are generally not energized during testing.

Salt spray: The test specimen undergoes corrosion as a result of an electrochemical or complex chemical reaction with a neutral or acidified salt solution. The salt solution forms a fine electrolytic structure.

Dry condition: Heated air in the chamber can cause water to evaporate from the surface of the test sample due to decreased relative humidity and increased sample temperature. This leads to an increase in the concentration of the solution and accelerates the corrosion process by speeding up chemical reactions. During this condition, salt precipitates from the solution onto the surface of the test sample. Evaporation and heating rates may vary depending on the test chamber and the test sample.

Humid condition:

• From dry to moist state: As the relative humidity increases, salt crystals precipitated on the sample surface begin the corrosion process again by absorbing water vapor until a liquid electrolytic solution is formed.
• Salt mist to moist state: The moist state maintains the existing wetness on the test sample surface at the end of the salt mist period without excessive dilution of the solution that may result from moisture condensation.

Standard atmosphere: The test specimen is allowed to equilibrate under standard laboratory conditions, which results in gradual drying and loosening in most corrosion reactions. In practice, a dry atmosphere period may occur during work breaks, e.g., weekends. The inclusion of such a dry period can lead to corrosion mechanisms that may be quite different from those under continuously wet conditions. The test program is selected to comply with the timelines given in the standard. The sodium chloride solution is prepared in accordance with the requirements of the ISO 9227 standard. The sodium chloride concentration of the collected spray solution is 50 g/l plus/minus 5 g/l.

pH adjustment for neutral salt solution: The neutral salt solution test must comply with the requirements of the ISO 9227 standard.

pH adjustment for acidified salt solution : To the prepared 10 liters of neutral 5% sodium chloride solution, the following reagents are added: 12 ml nitric acid, 17,3 ml sulfuric acid, and a sufficient amount of 10% mass fraction sodium hydroxide solution (approximately 300 ml) to adjust the pH of the solution to 3,5 plus/minus 0,1. The pH of the sprayed solution collected in the reservoir is between 3,4 and 3,6 at 25 degrees Celsius.

If necessary, the solution is filtered before placing it in the chamber of the device to remove solids that may clog the holes of the spray device.

Among the numerous testing, measurement, analysis and evaluation studies our organization provides for businesses in various sectors, with its trained and expert staff and advanced technological equipment, "EN IEC 60068-2-52 Environmental tests - Part 2-52: Tests - Test Kb: It also provides testing services defined in the “salt fog, cyclic (sodium chloride solution)” standard.