Cor­ro­sion test­ing - a com­par­i­son

Day after day, corrosion impacts components in and on cars, wind energy units or bridges. Having a surface coating tailored to the requirements is therefore all the more important. To simulate the stresses on parts fitted, prior to construction a series of tests are carried out to put the components and their protective coatings through their paces.

In practice – and in part demanded by the component manufacturers – various laboratory test procedures are applied, which can be divided into two categories: short-term tests and long-term tests. Short-term tests include constant climate tests and climatic extremes tests, as well as independent tests, for example those of car manufacturers.

Over a short, specific period of time these short-term tests simulate the daily stresses, taking account of various parameters such as temperature and humidity or dryness and stress phases. The tests provide numerous findings for the evaluation and optimisation of the corrosion resistance of surface coatings and therefore the parts themselves.

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Test chamber for the salt spray test ISO9227 NSS

Long-term tests

In addition to short-term tests there are also long-term tests such as outdoor weathering tests. These can be conducted on land or water and demonstrate across the course of years the realistic corrosion behaviour of components and their surface coatings. Extreme wind speeds, strong temperature fluctuations, UV rays and in some cases salt water all impact the exposed components. Outdoor weathering tests differ greatly from short-term tests, as they are not conducted in the laboratory, but in the actual environments of the components. Nevertheless, due to the various parameters there is no correlation to the short-term tests.


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Exposure of parts and components on FINO2, a research platform in the Baltic Sea

o reflect as great a variance of environmental stresses as possible, Dörken conducts both short-term laboratory tests and long-term tests. The latter are currently carried out on Heligoland, on an offshore platform in the Baltic Sea, in Vienna and in Herdecke, near the company headquarters. At the same time, a new exposure test is also planned in Palavas, France. Here parts such as metric bolts or sheets will be placed, having previously been coated with various coating systems from Dörken as well as reference systems. In some cases, scoring will also be applied, to simulate corrosion behaviour in parts that are already damaged. (Photo) documentation occurs at regular intervals, together with evaluation of the findings of the test series.