The causes and conditions of flash rust in the construction of water-based steel structure anticorrosion coatings

The causes of flash rust in the construction of water-based anti-corrosion coatings seem insanity. There is a saying: "The problem of flash rust of water-based coatings refers to the rust spot phenomenon in the drying process of newly constructed water-based coatings, which mainly occurs in corroded interfaces or newly resified steel surfaces." The production of flash rust may be related to the dissolution and precipitation of iron compounds, the severity of flash rust depends on the coating system, coatings such as polyvinyl acetate latex at low
PH
, low temperature and high humidity, prolonging the contact time of water and substrates, prone to flash rust.Of course, there are other different statements: "Water-like paint film has a process, any piece of metal is not absolutely pure and absolutely smooth, which will produce a small block of different bits, different bits between the small pieces of electricity, metal oxidation from which the formation of rust spots, that is, flash rust." From these different statements, it can be seen that the production of flash rust is an electrochemical process.because the water-based coating itself is a conductor, the presence of a power difference between different areas of the formation of charge migration channels, so that corrosion in the water-based coating filming process occurred in a short period of time, forming a flash rust. Obviously, the longer the wet paint film is maintained, the more serious the flash rust phenomenon, which can explain the low temperature and high humidity of the flash rust phenomenon is more serious reasons.fact, because flash rust is an electrochemical phenomenon, the lively metal in front of hydrogen will encounter this problem when constructing with water-based coatings. In our coating tests of steel, cast iron, aluminum and aluminum alloys, galvanized plates and other substrates, we found that the areas prone to flash rust are: cast iron, aluminum, carbon steel, galvanized zinc plate
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grinding
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, makou iron
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grinding
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, iron plate or iron wire, aluminum alloy.in many aspects of experiments and peer-reflected situation, cast iron is not only the most prone to flash rust substrate, but also one of the most difficult to solve the problem of flash rust substrate. The reason for this situation can be explained from the lively condition of the metal and the purity of the material: cast iron contains many impurities and complex composition, it is easy to form a cell of different potentials, so in the process of water-grade paint construction is more prone to flash rust. However, limited to the author's level and experimental conditions, the above sorting needs more in-depth experiments and demonstration.electrochemical phenomenon is the root cause of flash rust, but in the process of water-based paint construction, the conditions of flash rust are very complex. In addition to the substrate differences discussed above, the
PH
value of the coating, the temperature and humidity of the construction environment, wind speed, paint film thickness and so on, all have an impact on the phenomenon of flash rust.
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