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Polypyrrole-Based Composite Coatings
Published in S.K. Dhawan, Hema Bhandari, Gazala Ruhi, Brij Mohan Singh Bisht, Pradeep Sambyal, Corrosion Preventive Materials and Corrosion Testing, 2020
S.K. Dhawan, Hema Bhandari, Gazala Ruhi, Brij Mohan Singh Bisht, Pradeep Sambyal
Salt spray test is an accelerated corrosion testing method using high salt content (5.0%NaCl) and high relative humidity. The coated metal panels are exposed to salt spray fog/mist under standard conditions as mentioned in ASTM B117. The progress of corrosion is noticed for a given period to evaluate the corrosion endurance of the paints/coatings. An intentional scribe mark is introduced on the coated metal panels, and the appearance of blisters, the occurrence of undercoating corrosion, etc., are studied. PPy-based composite coatings have shown superior corrosion resistance under salt spray fog of NaCl. Ruhi et al. (2014, 2015) have discussed salt spray test results of PPy/SiO2, PPy/flyash and PPy/chitosan composite coatings developed on the mild steel surface. Figure 5.20 shows the photographs of epoxy-coated mild steel panels (EC) and epoxy with different wt% loading of PPy-flyash composite (PF1, PF2 and PF3) coated steel panels after exposure to salt spray fog for 150 days.
Investigation of the Corrosion Rate
Published in Michael Dornbusch, Corrosion Analysis, 2018
The challenge to describe corrosion processes on real parts in real environments is caused by the long period necessary to detect the corrosion phenomenon and the fact that corrosion starts with a local process. Paik et al. [67] detected a Weibull distribution of the corrosion rate of organic coated ballast tanks in ships over a period of more than 10 years with a broad distribution caused by the uncertainties to detect the corrosion process. For instance in ref. [68] the outdoor exposure of organic coated steel samples has to extend from two to five years (Berlin 1970) to detect differences even on low performance coating systems in contrast to the two-year exposure in maritime environment. Therefore fast corrosion tests have been developed in every industry. Some test methods of the general and the automotive industry are summarized in Table 4.6. The term “fast” is very relative in accelerated corrosion tests because a normal Salt Spray Test (SST) takes 1000 hours, i.e., six weeks, and the most alternating climate tests in the automotive industry takes from 10 up to 30 weeks. In the aerospace industry specifications for the salt spray test duration of 3000 hours (ISO 9227) are common and up to 9000 hours (ISO 72523) are possible, i.e., 53 weeks. At least the tests are faster than the outdoor-exposure for years. This is the main reason for the development of really fast corrosion tests based on electrochemical methods mentioned above. The different industrial test methods are discussed and illustrated in the following chapters.
Corrosion Testing: Practice
Published in Ole Øystein Knudsen, Amy Forsgren, Corrosion Control Through Organic Coatings, 2017
Ole Øystein Knudsen, Amy Forsgren
Lyon et al. [24] point out that the high sodium chloride content of the salt spray test can result in corrosion morphologies and behaviors that are not representative of natural conditions. Harrison and Tickle have pointed out that the test is inappropriate for use on zinc— galvanized substrates or primers with zinc phosphate pigments, for example— because, in the constant wetness of the salt spray test, zinc undergoes a corrosion mechanism that it would not undergo in real service [25]. This is a well-known and well-documented phenomenon and is discussed in depth in Chapter 13.
Experimental investigation on the effect of corrosion and erosion on the shell and tube-type heat exchanger
Published in International Journal of Ambient Energy, 2021
R. Siva, G. Mageshwaran, Sanjana Kallat, Jeya Jeevahan
Salt spray test is conducted on the material for 24 hours, where the spray solution consists of sodium chloride solution. The material sample has a thickness of 10 mm and the air pressure is from 10 to 25 psi. Sodium chloride solution reacts with the material and results in the salt form. The specimen before the test is shown in Figure 9(a). Before the test is conducted, the material’s weight is noted and is compared to the weight of the specimen after the salt spray test. The rust is formed in the carbon steel material. Carbon steel material is immersed in the solution of sodium chloride. The specimen after the salt spray test is shown in Figure 9(b).
Performance of commercial LDH traps for chloride ion in a commercial corrosion protection primer for petrochemical industry
Published in Corrosion Engineering, Science and Technology, 2020
Andrea Renata Deip, Débora Abrantes Leal, George Hideki Sakae, Frederico Maia, Marcos Antonio Coelho Berton, Mário Guerreiro Silva Ferreira, Cláudia Eliana Bruno Marino
In accordance with Petrobras N-2630 standard, after 1500 h of exposure to a salt spray chamber, the substrates coated with the commercial primer and with the primer containing LDH-BTA were analysed to evaluate the advancement in corrosion in the defect. The salt spray test is usually used in the industry for quality control and corrosion protection efficiency testing.