Introduction to Salt Spray Corrosion Test Chamber for Salt Corrosion Test

The Salt Corrosion Test is a method that uses a test device called a “Salt Spray Corrosion Test Chamber” with a certain volume space to assess the corrosion resistance quality of a product to salt spray corrosion through artificial means within its volume space. The salt concentration of chloride in the artificial salt spray environment is several times or tens of times higher than that in a natural environment, which greatly increases the level of corrosion and shortens the time required to obtain results from the salt spray corrosion test.

Salt Corrosion Test standards provide specific and clear regulations on salt spray test conditions such as temperature, humidity, concentration of sodium chloride solution, and pH value. In addition, they also propose technical requirements for the performance of the salt spray test chamber. The choice of which salt spray test standard to adopt for a particular product depends on the characteristics of the salt spray test, the corrosion rate of the metal, and the sensitivity to salt spray.

The salt spray test standards include the following:
– GB/T2423.17-1993 “Basic Environmental Testing Procedures for Electrical and Electronic Products – Test Ka: Salt Spray Test Method”
– GB/T2423.18-2000 “Environmental Testing of Electrical and Electronic Products – Part 2: Test Kb: Salt Spray, Cyclic (Salt Solution)”
– GB5938-86 “Test Method for Corrosion Resistance of Light Industrial Products Metal Coatings and Chemical Treatment Layers”
– GB/T1771-91 “Determination of Resistance to Neutral Salt Spray Performance of Paints and Varnishes”

There are several methods for determining the results of salt spray tests:
1. Rating method: The percentage of corroded area to the total area is divided into several levels using a specific method, and a certain level is used as the criterion for qualification. This method is suitable for evaluating flat samples.
2. Weight determination method: The weight change of samples before and after the corrosion test is calculated to evaluate the corrosion resistance quality of the samples. This method is suitable for assessing the corrosion resistance quality of a specific metal.
3. Appearance of corrosion products: This is a qualitative method that determines the qualification of samples based on whether corrosion occurs after the salt spray corrosion test. This method is commonly used in product standards.
4. Statistical analysis of corrosion data: This method is mainly used for analyzing and statistically analyzing the corrosion situation, rather than making specific quality judgments for a particular product.

The artificial simulated salt spray test includes neutral salt spray test (NSS test), acetic acid salt spray test (ASS test), copper accelerated acetic acidsalt spray test (CASS test), and alternate salt spray test:
1. Neutral salt spray test (NSS test) is the earliest and most widely used accelerated corrosion test method. It uses a 5% sodium chloride saltwater solution with a neutral pH (6-7) as the spray solution. The test temperature is set at 35°C, and the salt spray deposition rate is required to be between 1-2 ml/80cm².h.

2. Acetic acid salt spray test (ASS test) is developed from the neutral salt spray test. It involves adding some glacial acetic acid to a 5% sodium chloride solution, lowering the pH to around 3 to create an acidic environment. The corrosion rate in acetic acid salt spray is approximately three times faster than that in neutral salt spray.
3. Copper accelerated acetic acid salt spray test (CASS test) is a recently developed rapid salt spray corrosion test. The test temperature is set at 50°C, and a small amount of copper salt, such as cupric chloride, is added to the salt solution to induce severe corrosion. The corrosion rate in CASS test is approximately eight times that in the neutral test.
4. Alternate salt spray test, also known as comprehensive salt spraytest, combines neutral salt spray test and constant humidity test. It is mainly used for cavity-type whole-machine products. By subjecting the product to alternating salt spray and humidity conditions, it assesses whether there are changes in the electrical and mechanical performance of the whole-machine product.

The impact of saltwater concentration on the results of salt spray testing:
Saltwater concentration is a crucial factor in salt spray testing as it directly affects the level of corrosion and the resulting outcome of the test. Generally, the higher the saltwater concentration, the more severe the corrosion observed in the test results. Therefore, when conducting salt spray testing, the saltwater concentration should be determined based on the actual conditions in which the product will be used in order to ensure the accuracy of the testing results.

Methods for determining saltwater concentration:
There are two main methods for determining saltwater concentration: the weighing method and the colorimetric method.

The weighing method involves dissolving a specific quantity of salt in a specific volume of water and then determining the concentration of the saltwater through weighing. Firstly, the mass of the salt used and the volume of water it is dissolved in need to be known. Then, a specific quantity of salt is added to a specific volume of water and thoroughly mixed. The saltwater is then filtered, and the mass of the filtered salt is measured using a balance. By comparing the mass of the filtered salt with the mass of the original salt, the concentration of the saltwater can be calculated.

The colorimetric method is a simple and quick method that determinessaltwater concentration by comparing the color of the test saltwater with a standard concentration saltwater. Initially, a series of standard concentration saltwater of known concentrations is prepared. Then, both the test saltwater and the standard saltwater are placed in white containers and their colors are compared. If the color of the test saltwater is similar to that of a particular standard saltwater, then the concentration of the test saltwater can be determined to be the same as that of the corresponding standard saltwater.

Conclusion and recommendations: Accurately determining saltwater concentration is crucial when conducting salt spray testing. Both excessively high or low saltwater concentrations can result in inaccurate testing results. Therefore, it is recommended to select the appropriate standard grade and corresponding saltwater concentration based on the actual application environment and requirements of the product before conducting the salt spray test. Additionally, choosing the appropriate method for determining saltwater concentration is crucial to ensure the accuracy of the testing results.

Furthermore, it is important to note that salt spray testing only evaluates the corrosion resistance of a product in a salt spray environment, and there may be other factors to consider in the actual usage environment. Therefore, it is necessary to consider various corrosion factors and protective measures in the product design and production process in order to improve the overall corrosion resistance performance of the product.

Salt Spray Test Chamber | Salt Fog Test | ASTM B117 Salt Spray ChamberSalt Spray Test Chamber is applicable to the salt spray corrosive test for the protection layer of components, parts, electronic and electrical parts and metal materials and industrial products. The salt fog test chamber meets the following standards: IEC60068-2-11 (GB/T2423.17), GB/T10125, GB/T1771, ISO9227, ASTM-B117, GB/T2423-18, QBT3826, QBT3827, IEC 60068-2-52, ASTM-B368, MIL-STD-202, EIA-364-26, GJB150, DIN50021-75, ISO3768, 3769, 3770; CNS 3627, 3885, 4159, 7669 etc.

Lisun Instruments Limited was found by LISUN GROUP in 2003. LISUN quality system has been strictly certified by ISO9001:2015. As a CIE Membership, LISUN products are designed based on CIE, IEC and other international or national standards. All products passed CE certificate and authenticated by the third party lab.

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