The selection of coating materials is very important in the casting process, as it can affect the surface quality of the casting, the adhesion and durability of the coating, and other aspects. Below, we will elaborate in detail on how to choose suitable coating materials from the aspects of coating types, coating performance requirements, and coating selection criteria.

1、 Types of coatings

The types of coatings can be divided into various types based on their usage purpose and coating method, such as rust proof paint, lubricating paint, thermal insulation paint, flame retardant paint, etc. The commonly used types of coatings in the casting process include anti sticking agents, dewaxing agents, mold release agents, and refractory coatings.

1. Anti adhesive: Coating anti adhesive on the surface of castings can effectively prevent adhesion between castings and sand molds, making castings easy to demold. Anti adhesive is usually a liquid that can be applied to sand molds through spraying, brushing, and other methods.

2. Dewaxing agent: During the casting process, wax molds need to be made. Before casting, the wax mold needs to be evaporated from the sand mold through steam, high temperature, and other methods. At this time, a dewaxing agent needs to be coated on the wax mold. The selection of dewaxing agent should be based on the characteristics of wax mold materials and the requirements of sand mold materials.

3. Release agent: During the casting process, the release agent applied to the surface of the sand mold and mold can make the casting easy to release and improve the surface smoothness of the casting. The selection of release agent should be based on the requirements of casting material, sand mold material, and coating performance.

4. Refractory coating: In some high-temperature casting, it is necessary to apply refractory coating to protect sand molds and molds, and prevent corrosion of high-temperature molten metal. The selection of refractory coatings should be based on casting materials, casting temperature, coating performance, and surface quality requirements.

2、 Performance requirements for coatings

The performance requirements of coatings determine the selection range of coatings. In the casting process, the performance requirements of coatings usually include the following aspects:

1. Heat resistance: The coating should have a certain degree of high-temperature resistance to prevent deterioration or peeling during the casting process. For high-temperature casting, the heat resistance performance of coatings is required to be higher.

2. Adhesion: The adhesion between the coating and the surface of the sand mold or mold should be good, so that the coating is not easy to peel off and the quality of the casting surface can be improved.

3. Smooth finish: The coating should have a certain level of smoothness to ensure the smoothness and brightness of the casting surface.

4. Corrosion resistance: For the casting of some special materials, the coating should have a certain degree of corrosion resistance to protect the sand mold or mold from corrosion.

5. Environmental friendliness: Coatings should meet environmental requirements, contain no harmful substances, and not cause pollution to the environment.

3、 Selection criteria for coatings

When selecting suitable coating materials, the following criteria can be used for selection:

1. Casting material: The selection of coating should be based on the characteristics of the casting material. The properties of coatings may vary for castings made of different materials.

2. Casting temperature: The selection of coating should be based on the casting temperature. For high-temperature casting, the heat resistance performance of coatings is required to be higher.

3. Coating performance: The performance requirements of the coating should match the surface quality requirements of the casting. For castings that require higher surface quality, the performance requirements of coatings should also be higher.

4. Coating cost: The cost of coating is also an important factor in selection. The cost of coating should match the value of the casting.

5. Construction method: The selection of paint should also consider the painting method, such as spraying, brushing, immersion coating, etc. Different painting methods also have different requirements for coatings.

In summary, selecting the appropriate coating material during the casting process is very important. The selection of coatings should be based on the type, performance requirements, and selection criteria of the coatings. Only by selecting appropriate coating materials can the surface quality and coating quality of castings be improved, and the overall performance of castings be improved.