Research and Application of Heavy-duty Anticorrosive Coatings for Railway Steel Bridges

At present, China's railway network is in the stage of expanding the scale, improving the structure, improving the quality, rapidly expanding the transportation capacity and rapidly improving the equipment level

Corrosion and protection principle of railway steel bridge

The main materials used to manufacture railway steel bridge steel, and steel is the metal of a large class of paint online coatingol.

1.

Chemical corrosion process Chemical corrosion is a process in which a gas or liquid medium chemically reacts with the metal surface to produce compounds, thereby causing the metal surface to suffer corrosion damage

2.

The corrosion of metals in the atmosphere is mainly electrochemical corrosion

The main factors affecting metal corrosion

1.

It is well known that different metals have different electrode potentials and different metallographic structures, and their stability, that is, corrosion resistance, is different
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However, steels with the same chemical composition have different corrosion resistance due to different heat treatment processes
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In addition, metal processing due to uneven thermal stress distribution during forging, casting, and electric welding, or grain deformation during thermal processing, may cause differences in the potential of the internal electrodes of the metal, and accelerate the corrosion of the metal itself
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2.
The influence of ambient temperature

In general, as the temperature increases, the corrosion rate of metals in the electrolyte solution increases
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In addition, in regions with a continental climate, where the temperature difference between day and night is large, and the relative humidity in the atmosphere at night rises, moisture in the air will coalesce on the metal surface in the form of condensation, which provides good conditions for metal rust
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3.
The influence of environmental humidity

Especially under the conditions of high temperature and high humidity, metal is most prone to rust
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Among them, the most corrosive factor is the humid and heavily polluted industrial atmosphere and the influence of temperature changes is far less important than the influence of humidity changes, because high relative humidity can easily form a corrosive water film on the metal surface
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Research Progress of Anticorrosive Coatings for Railway Bridge Steel Structures

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Alkyd resin coating

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Silicone coating

The scientific name of silicone resin is polysiloxane resin, its main chain contains silicon-oxygen bonds, and the side groups are high polymers with organic groups.
Silicone resins for coatings are generally methyl trichlorosilane, dimethyl dichloride Silane, phenyltrichlorosilane, diphenyldichlorosilane and methylphenyldichlorosilane are made by hydrolysis and polycondensation as raw materials
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Silicone resin has good temperature resistance, water resistance, chemical resistance and UV resistance
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When the silicone resin is used alone, the paint film is too soft, so it is often blended with other resins
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Such as alkyd resins, polycarbonate resins, epoxy resins, acrylic resins, etc.
In combination, these resins can improve the hardness and drying speed of the paint film, while silicone resins provide gloss and color retention
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The modification methods of silicone resin and various resins are different.
According to needs, it can be modified into coatings required by different places
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Concluding remarks

At present, due to the low price of traditional phenolic resin and alkyd resin anti-corrosion coatings, they are still used by many units in anti-corrosion coating projects, but due to their inherent performance defects, coupled with the development of various high-performance anti-corrosion coatings They have been developed and gradually applied.
People in the industry and paint users have gradually understood and accepted high-performance products.
The output of traditional phenolic, alkyd and other oil-based paints as a percentage of the total output of anti-corrosion coatings has been on a downward trend.
Compared with that, there is still a certain gap
.