Organic coatings accelerated tests

Figure 34.3 illustrates how metals (galvanized steel, copper, and aluminum) are pretreated with a sol-gel layer doped with inhibitors prior to the application of an organic coating. Accelerated tests in spray chamber clearly show that such a sol-gel layer provides painted metals with prolonged improved corrosion resistance [21]. 

Experimental study of metal protection by organic coatings Accelerated exposure tests... 

The performance of organic finishes on test is evaluated by visual observation and by physical tests made upon coated specimens that have been exposed for various periods of time to natural or accelerated weathering conditions. Electrical tests are sometimes used on immersed specimens. 

Various conditions of accelerated corrosion testing are summarized in Table 1.10. According to ISO 14993 [85], water condensation on the test specimens should not occur under wet conditions. The methods of testing organic coatings on metallic materials according to ISO 11997-1 under cyclic corrosion conditions include condensation of water on the test surface during the period of humidity [87]. 

D6675—01(2011) Standard Practice for Salt-Accelerated Outdoor Cosmetic Corrosion Testing of Organic Coatings on Automotive Sheet Steel... 

Fekete, E. and B. Lengyel (2005). Accelerated testing of waterborne coatings. Progress in organic coatings 54, 211 215. 

Exposure tests, accelerated or not, are still most widely used in industry for evaluating the durability of organic coatings and their effectiveness for corrosion... 

AISI [I2-/4] luis taken a leadership role to develop and evaluate methodology based on laboratory experiments, field exposure history, and theoretical and empirical models through an open forum of all interested parties (mainly North American automotive and steel industries), organized as the Corrosion Task Force of the AISI. The task force developed an improved laboratory-accelerated test for ranking the cosmetic corrosion resistance of coated automotive steel sheet products. This approach serves as a model for methodology development in areas of nonmetaUic coatings corrosion testing. 

Traditionally, accelerated testing of organic coatings has been attempted in the laboratory by exaggerating the stresses (heat, moisture, UV, and salt exposure) that age the coating. The prevailing philosophy has been that more stress = more acceleration. 

As indicated in Table 6, salt spray testing is the most popular form of testing for protective coatings. These tests have been used for more than 90 years as accelerated tests in order to determine the degree of protection afforded by both inorganic and organic coatings on a metallic base. Table 5 lists several widely used salt spray tests. 

Yau, Y.-H., Hinnerschietz, S.J. and Fountoulakis, S.G., Performance of organic/metal-lic composite coated sheet steels in accelerated cyclic corrosion tests, in Proc. Corrosion 95, NACE, Houston, 1995, Paper 396. 

Figure 20-3 shows the results of the accelerated weathering tests on our inorganic coating material and other organic paints. Luster retention rate is defined as follows ... 

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