Corrosion testing is a chemical or electrochemical process that studies the effect of corrosive materials on various metals. Salt spray testing, also known as “weathering”, is an accelerated corrosion testing method that evaluates the durability of finishes and coatings by exposing samples to a mist or aerosol of fine salt particles that simulates natural weather conditions. Let’s discuss corrosion testing and salt spray testing further.

What is corrosion testing?

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Corrosion testing is designed to predict the behavior of metals under different corrosion conditions by testing under such conditions. The two main types of corrosion testing are laboratory corrosion testing and field corrosion testing.

Laboratory testing can be performed on small metal samples, while field testing is used to evaluate large metal objects and structures. Laboratory corrosion testing is performed under controlled conditions, while field testing is performed in actual environments where metals are used.

There are various laboratory corrosion tests, including:

– Closed-loop testing

– Electrochemical impedance spectroscopy (EIS)

– Potentiodynamic polarization (PD)

– Salt spray test (ASTMB117, ENISO9227, ISO17025 or JISZ2371)

What is salt spray testing?

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Salt spray testing is a standardized method to accelerate corrosion. It involves placing a metal sample in a chamber containing fine mist or salt particle aerosols, representing natural weather conditions. The damage to the samples was visually measured and compared to other samples, and the results were reported as equivalent “exposure times.”

Salt spray testing is used to evaluate the durability of metal surface finishes and coatings. This test can be used to evaluate the impact of different exposure conditions, such as humidity and temperature, on the corrosion resistance of the coating. It is also used to compare the performance of different coatings and finishes.

1.NSS or neutral salt spray

Neutral salt spray (NSS) testing is used to assess the impact of the environment on metal surfaces without affecting any protective or decorative properties. Corrosion tends to be slow and uniform. Suitable for ferrous and non-ferrous metals such as aluminum alloy, magnesium alloy, copper alloy, zinc alloy, titanium alloy, etc. The test cycle was performed at a constant chamber temperature of 35 degrees Celsius.

2.AASS or acetate salt spray

The acetic acid salt spray (AASS) test is used to assess the impact of the environment on metal surfaces, and the addition of acetic acid enhances corrosion attacks. Corrosion tends to be more aggressive and uneven. It is mainly used in ferrous metals such as nickel, steel and iron. The optimal temperature is 50 degrees Celsius.

3. CASS or copper accelerated acetate salt spray

The copper-accelerated acetate salt spray (CASS) test is used to evaluate the corrosion resistance of zinc, cadmium and polymer coatings. You can also use it to evaluate the impact of the environment added to glacial acetic acid and other dihydrates on metal surfaces.

The ASTMB117 standard defines the procedures for conducting salt spray testing and is approved by the American Society for Testing and Materials. The standard specifies the type of salt to be used, the testing conditions and the parameters to be measured.

Salt spray testing is used to evaluate the corrosion resistance of metal surface coatings and finishes. This test can be used to evaluate the impact of different exposure conditions, such as humidity and temperature, on the corrosion resistance of the coating. It is also used to compare the performance of different coatings and finishes.

Standardization of salt spray testing allows comparison of results from different laboratories. This makes it an important tool for assessing the corrosion resistance of new and existing coatings and finishes. Manufacturers are also widely used to prove compliance with environmental regulations, such as the Restriction of Hazardous Substances Directive (RoHS).

What is ISO17025 and how does it relate to salt spray testing?

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ISO17025 is an international standard for evaluation and calibration in test laboratories. It sets out the requirements that a laboratory must meet to be recognized. ISO9227 is also one of the international standards that specifies a calibration method for using corrosion reference samples to assess the repeatability and reproducibility of salt spray tests. Other important related standards to be aware of include JISZ2371 and ASTMG85.

Laboratory certification is important because it ensures that the results of corrosion testing (such as salt spray testing) are reliable and repeatable. This makes it possible to use test results performed in different laboratories to compare the corrosion resistance of coatings and finishes.

the term

Here are some of the terms used in salt spray testing:

deionized water

Deionized water is deionized water. Used to wash metal surfaces before and after salt spray testing.

glacial acetic acid

Glacial acetic acid is an acid used in the acetic acid salt spray test. It is a highly corrosive acid used to accelerate corrosion on metal surfaces.

salt solution

A salt solution is a mixture of salt and water used to create salt mist during testing. Also known as sodium chloride solution.

conclusion

In summary, salt spray testing is used to evaluate the corrosion resistance of metallic surface coatings and finishes. The ASTMB117 standard defines the procedure for conducting salt spray testing. ISO17025 is an international standard for evaluation and calibration in test laboratories. It sets out the requirements that a laboratory must meet to be recognized. Other important relevant standards are ISO9227, JISZ2371 and ASTMG85.

Laboratory certification is important because it ensures that the results of corrosion testing (such as salt spray testing) are reliable and repeatable. This makes it possible to use test results performed in different laboratories to compare the corrosion resistance of coatings and finishes. ThaiParkerizing provides salt spray testing as part of our corrosion testing services. Our standardized testing methods help ensure that your material will perform as intended in its actual environment and, most importantly, that your material will be suitable for its intended use.

As a leader in coating, surface treatment and heat treatment technologies for a wide range of applications, including customers in the automotive parts industry, we persist in research and development to create effective solutions for customer needs. Our broad range of products and services includes surface and metallurgical analysis as well as various tests described below.