Both the spring metal surface coating and organic coating should meet the requirements of dense, uniform coating (plating) and strong bonding with the substrate. The coating (plating) layer, such as coating (plating) layer shedding, bubbling or blooming, and partial non-coating, etc., is mostly caused by the unclean surface of the metal before coating (plating). Compared with organic solvent coatings, spring metal surface coating treatments that use water as solvent, such as electroplating, anodizing, phosphating, and water-based coating coating, are more sensitive to organic contamination on the metal surface, even for monolayer contamination. Anything may lead to the failure of the entire process. Therefore, the cleanliness of the material surface before coating (plating) is very important. As a Bearing Preload Disc Springs Manufacturer, I would like to share with you.
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The oil stains on the bright metal surface can be observed with the naked eye and with the aid of a magnifying glass or an optical microscope. The disadvantage is that the passive oxide film on the metal surface and extremely thin oil stains will not be detected. For rough and non-glossy metal surfaces, the above methods seem powerless, but you can wipe the surface with clean, white cotton, cloth, paper, and then observe whether it is clean to determine whether the metal surface is clean.
According to the effect of surface oil on its surface energy, the surface energy is determined by whether the metal is infiltrated in a series of test solutions with different surface tensions, and the cleanliness of the surface is judged based on this.
Drop the degreasing agent on the metal surface, and then evaporate it to dryness. If there are no traces, the metal surface of the surface is clean. If there is a ring, it indicates that there is oil stains.
A clean metal surface is hydrophilic, so it can be completely wetted by water. When the metal surface contains oil, there will be a water-cut area that is not wetted by water. Based on the principle of whether it is hydrophilic, in addition to the simplest and commonly used exhalation method and nebulizer spray method, there are the following detection methods. Since the metal oxide film is also hydrophilic, most of these methods cannot detect whether the oxide film on the metal surface is degraded.
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