Salt Spray Accelerated Corrosion Testing

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Salt spray tests are accelerated corrosion tests used to check the relative corrosion resistance of metallic components. Frequently the tests are used to test the protective coatings applied to metallic substrates.

The tests are performed in a controlled corrosive environment designed to represent marine type atmospheric conditions. The results are accelerated by the test temperature, the test solution, the degree of wetness etc.

There is, however, no direct correlation between the test duration and the expected service life. Despite this, salt spray testing is widely used in industry for the evaluation of corrosion resistance of finished surfaces or parts in order to predict relative suitability for use in service or as a quality control test.

The test originated in the USA in the early 20th century. Nowadays salt spray testing is performed to a number of standardized test methods including:

ISO 9227
DIN 50021
ASTM B117

The standards define how the tests must be performed, but do not define test duration or acceptance/rejection criteria.

Materials Technology offer the neutral salt spray test ( NSS ) as standard, which is perhaps the most commonly used salt spray test, and is performed with a solution of NaCl (typically 5%) at a neutral pH between 6.5 & 7.2. The duration of the test can range significantly, but will typically run from 500-1000 hours.

Other versions of the test include Copper Accelerated Acetic Salt Spray ( CASS ) and Acetic Acid Salt Spray ( AASS ). The CASS test and the AASS test have been found to be especially useful for testing decorative coatings of copper+nickel+chromium, or Nickel+Chromium. They have also been found suitable for testing anodic coatings on aluminium. Materials Technology can also offer these tests on request.

UV damage on industrial coatings can make them more susceptible to corrosive attack. For this reason versions of this test can also be performed in conjunction with accelerated UV weathering, whereby industrial coatings are aged by a repeated cycle of a weeks accelerated corrosion testing followed by a weeks in a QUV chamber.

Materials Technology offer a range of accelerated environmental tests including salt spray testing and accelerated UV weathering testing. Please contact us to discuss your requirements using the details below:

Contact:
Materials Technology Ltd.
5 Rushington Court
Rushington Business Park
Chapel Lane
Southampton
Hampshire SO40 9NA
Tel: 02380 580240
Fax: 02380 661758