Paint Craters

Modern car coatings have a series of tasks. The multilayer structure of dip coating, filler, base coating, and clear coat protects the car body from corrosion and withstands the stress from external conditions like weather conditions, stone impact, road salt, and car washes year in year out. Defects, e.g. paint craters, compromise this protection, deteriorate the optical quality of the surface and lead to considerable economic damage.

To prevent the creation of paint craters in the production it is necessary to know the causes in individual cases. ToF-SIMS makes it possible to identify the smallest amount of a compound on surface areas with a diameter of less than 100 µm. The paint layer in the shown example has a large amount of clear craters of different sizes close to each other. In the crater, Fluorine-containing hydrocarbons were detected with high intensities. Comparative studies clarified that these emanated from a high performance lubricant based on a perfluorinated polyether, that is used in the lubrication of the transport line in the production hall.

Besides chemical contaminations (e.g. greases) serious coating failures are often caused by inclusions of particles or fibres. Additionally, formation of bubbles or inaccurately oriented coating components (e.g. flakes) are well-known reasons for coating faults. Depending on the defect characteristics several analytical methods like light microscopy, infrared spectroscopy, SEM-EDX or ToF-SIMS are well-established for identifying the nature of coating failures.

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