Anti-oxidation coating and its preparation method and application

Abstract

The invention relates to an antioxidant coating as well as a preparation method and application thereof and belongs to the technical fields of metal fabricating and coatings for the metal fabricating.The antioxidant coating is prepared from the following materials in parts by weight: 30 to 50 parts of colloidal graphite powder, 30 to 50 parts of sodium silicate, 10 to 20 parts of iron powder, 5 to 15 parts of aluminum powder, 5 to 18 parts of kaolin, 10 to 30 parts of mica powder and 18 to 35 parts of boron trioxide. The coating is all prepared from solid powder, is applied to the surface ofa nuclear power forging by a spraying method, and can provide convenient antioxidant protection for the nuclear power forging forged and heated at the temperature of 1200 DEG C or above; oxidation weight increase caused by long-time heating process is reduced by 95 percent or above.

Description

technical field [0001] The invention relates to an anti-oxidation paint and its preparation method and application, and belongs to the technical field of metal forging and the paint used therefor. Background technique [0002] Large-scale forgings such as nuclear power pressure vessels, evaporators, voltage stabilizer cylinders, and heads manufactured for nuclear power plants are made of medium and low alloy steel such as SA508 and 18MND5, which are severely oxidized at high temperatures during the forging heating process. How to protect them from being oxidized or oxidized as little as possible during the process, especially at the forging temperature of 1200°C and above, is the goal that the forging industry has been pursuing. The free energy of steel at 1200°C and above is reduced due to the oxidation reaction process, and the reduction increases with the increase of temperature; high temperature corrosion is very serious, which not only brings a lot of waste, but also br...

AI Technical Summary

Problems solved by technology

However, there is still a big gap between the actual effect of anti-oxidation coatings and people's requirements.

Especially the anti-oxidation in the forging and heating process of large nuclear power forgings has not yet seen public information with good results. The anti-oxidation coatings used in the heat treatment process not only have many defects in effect, but also because the forging of large nuclear power forgings is a process that is repeated several times, Different from the simple heat treatment process, first of all, the surface area of ​​the forging that needs to be anti-oxidized is as high as tens of square meters. It is difficult to use the method of painting to meet the production requirements. At the same time, due to the large area, the usual heat treatment coating is expensive and requires multiple times. The second is that in addition to the first forging, the re-forged forgings need to be returned to the furnace and reheated to the forging temperature as soon as possible, so the surface temperature of the forgings coated with anti-oxidation coatings is relatively high, sometimes as high as nearly 1,000 degrees. The third is the surface condition of the forgings The difference is not only for the use of paint but also for the difficulty in forming the coating film

These characteristics make it impossible to use the existing heat treatment coatings to meet the anti-oxidation requirements in the forging heating process of nuclear power large forgings

For example, the Chinese invention patent application number is 201610385703.X "a protective coating for heat treatment of metal parts", the application number is 201611119022.5 "a common anti-oxidation coating and its use method" and the application number is 201810678051.8 "a high-temperature anti-oxidation coating for carbon steel heat treatment Coatings and their preparation methods” and so on. The coatings contain liquid components, basically rely on brushing construction, and the construction period is long. It is difficult to paint on the surface of large high-temperature (above 800 ° C) forgings, and the anti-oxidation effect is not good.

[0004] In addition, the existing high-temperature resistant and anti-oxidation coatings also have various defects, such as the solid components in the anti-oxidation coatings are very easy to precipitate and agglomerate, it is difficult to mix evenly during use, and the anti-oxidation effect is not obvious; Steel surface needs to be treated and it is difficult to remove after use

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