SAE J2334: not just another cyclic salt spray test

You cannot imagine a modern world without coatings. A coating protects our car when it is parked outside and it makes sure that our food does not stick to the pan. Coatings are even used on actual raincoats to make them waterproof. In other words, our everyday life is better protected thanks to coatings. The same goes for the industrial sector, where the protective properties of coatings are an imperative part of the smooth operating of an installation. To test the quality and performance of both existing and newly-developed coating systems, accelerated corrosion tests, such as the SAE J2334 test, offer the answer. 

The first accelerated corrosion tests, such as the neutral salt spray test according to ASTM B117 or ISO 9227, were continuous tests with only one stage. In the neutral salt spray test the coatings are continuously exposed to 35°C in a fog of a 5% NaCl solution. 

In order to better mimic the degradation mechanisms occurring in real life situations, the development of the SAE J2334 test commenced in 1988. The development began by selecting ten different materials, including different combinations of coating types/thickness and also uncoated materials. Panels of these standard materials were exposed on pick-up trucks who drove for five years through Montreal, Québec, St. Johns and Newfoundland including two of the most corrosive environments in North America. Similar experiments were performed in Michigan, Ohio and Pennsylvania. 

Different accelerated corrosion tests and methods were performed and the correlation between results of the accelerated tests and real life performance was investigated. Among all tests, the SAE J2334 yielded best correlation with the results of the on-vehicle exposure. 80 cycles (80 days) of testing corresponded roughly to an on-vehicle performance of 5 years. 

The cyclic salt spray test according to SAE J2334 is thus a field-correlated test. Results from the test provide an excellent correlation regarding cosmetic performance (blistering, red rust, …). Although the test is specifically designed for automotive coatings it can be used for other coatings and applications as well. Field correlation should then be performed.

Caterpillar is a perfect example of a company that has high demands for quality. Caterpillar requires all its suppliers to succeed in the SAE J2334 test based on specific criteria. In order to ensure continuity in quality, approved suppliers have to show positive results on a regular basis. For the last decade, Caterpillar has been relying on TÜV AUSTRIA Belgium, formerly METALogic, concerning SAE J2334. 

At TÜV AUSTRIA Belgium, formerly METALogic, we perform the SAE J2334 test in dedicated cabinets. The SAE J2334 test is part of our ISO 17025 scope to ensure that it is performed according to the highest quality standards. Besides SAE J2334, METALogic can perform a variety of accelerated corrosion tests on coatings and coating evaluations.