Coating knowledge: performance characteristics of organic and inorganic zinc rich coatings

Core tip: coating as a simple and economic and effective anti-corrosion means has thousands of years of history Since the industrial revolution, large-scale production of steel and other metal materials, in order to reduce the problem of metal corrosion, many measures have been taken, but so far organic coating is still the most effective, the most economical and the most common At present, zinc rich primer is the most common and important anticorrosive primer for steel structure and shop primer The development of modern industrial technology not only provides better technical material conditions for the development of anticorrosive coatings for steel structures, but also provides a broader market At the same time, it will also make anticorrosive coatings mature and perfect Zinc rich paint zinc rich paint in paint system Which is the price of Dajin diatom mud Recommended brief introduction: which is the price of Dajin diatom mud? How to buy genuine diatom mud? Guangdong diatom mud agent suggests placing a basin of cold water in the air conditioning room, so that the diatom mud wall can breathe effectively The feature of the breathing wall is obvious When the indoor air is dry, the diatom mud wall will release the absorbed water quickly Put it out to help regulate the indoor dry humidity It is suggested to place a basin of cold water in the air conditioning room, so that the wall of diatom mud can breathe effectively The feature of the wall that can breathe is obvious When the indoor air is relatively dry, the wall of diatom mud will absorb the water Coating home news: coating as a simple and economic and effective means of anti-corrosion has thousands of years of history Since the industrial revolution, large-scale production of steel and other metal materials, in order to reduce the problem of metal corrosion, many measures have been taken, but so far organic coating is still the most effective, the most economical and the most common At present, zinc rich primer is the most common and important anticorrosive primer for steel structure and shop primer The development of modern industrial technology not only provides better technical material conditions for the development of anticorrosive coatings for steel structures, but also provides a broader market At the same time, it will also make anticorrosive coatings mature and perfect Zinc rich coating zinc rich coating is mainly used in the form of zinc rich primer for the anticorrosion of various steel structures in the coating system Because its formula is rich in a large number of electrochemical antirust pigment zinc powder, it is called zinc rich coating Zinc rich coating has the advantages of hard film, good adhesion, strong anti rust ability, excellent three proofing performance, anti-oxidation and anti-corrosion performance, excellent cathodic protection and electrostatic conductivity, which has no adverse effect on welding performance It can be used with most of the coatings, and has become the most common and important primer in the field of anti-corrosion application of ferrous metals such as steel and iron It is used in atmospheric and marine anti-corrosion There are few competitors in the field of corruption Only the coated material is in the environment of acid and alkali corrosion, because these media can penetrate into and react with zinc powder easily to generate hydrogen, other antirust primers have to be used Zinc rich primer can be divided into two categories in production and application, namely, inorganic zinc rich primer with silicate as binder and organic zinc rich primer with epoxy resin as binder When they are used in the field of corrosion protection, they must meet the following matching requirements: ① because the zinc powder in the primer must be in close contact with steel to play its electrochemical protection role, the pre-treatment of the substrate surface is strictly required, and the coated substrate must be sandblasted to ensure its construction quality ② The film of zinc rich primer is usually thin and easy to be affected by the external environment medium, so it is generally not used alone, it must be equipped with appropriate intermediate paint and finish paint, and reach the specified film thickness Due to its good corrosion resistance and weldability, zinc rich primer is also widely used as shop primer, also known as steel pretreatment primer or maintenance primer The steel plate or steel structure parts coated with maintenance primer shall not be rusted during pretreatment, cutting and welding When the steel structure parts are installed, there is no need to sandblast The next primer or finish coat can be applied directly by removing the dirt on the surface of the coated objects with water Compared with other metals, zinc powder has the following characteristics: lighter than iron, good ductility, and can be made into alloy with iron The most important thing is its electrochemical activity Its standard electrode potential is - 0.76 V, which is more active than - 0.44 V of iron Zinc is melted and processed into fine-grained high-purity zinc powder, which is used as an important antirust pigment in anticorrosive coatings When the paint film is eroded, the zinc powder as anode will be corroded first, and the base steel as cathode will be protected Zinc powder, as the oxidation product of sacrificial anode, plays a sealing role in the coating, thus strengthening the protective effect of the coating on the substrate However, zinc powder is gradually consumed in the process of protecting substrate from erosion, but the speed is very slow The formation of its corrosion-resistant products reduces the potential difference between the coating and the substrate When the paint film is damaged, new metal zinc will be exposed, and the potential difference will immediately increase, resulting in a new round of strong cathodic protection Therefore, the corrosion of zinc rich paint will not spread from the damaged part of the paint film to the circumference In order to ensure that the zinc powder in the zinc rich primer can be closely combined with steel to play the role of conducting and sacrificing anode, and to ensure the working quality of the zinc rich primer, the international regulations have been made on the percentage of the zinc powder content in the zinc rich coating in the total dry film mass For example, sspc-paint 20, the standard of American Steel Structure Painting Association, specifies that inorganic zinc rich paint shall not be less than 74% and organic zinc rich paint shall not be less than 77% The reason why the zinc content of organic zinc rich paint is higher than that of inorganic zinc rich paint is that its conductivity is worse than that of inorganic zinc rich paint The content of zinc powder in the long-term anti-corrosion inorganic zinc rich coating products with many single coatings is up to 75% in the water-soluble paint and over 82% in the solvent coating The requirements for the thickness of zinc rich primer are also different for different application purposes, and the requirements for the size and shape of zinc powder particles are also different, as shown in Table 1 Home of coatings is specialized in coatings, diatom mud, paint coating, coating technology, fire retardant coating news and coating, diatom mud, paint coating, coating technology, fire retardant coating decoration knowledge and decoration renderings,