What Role Does Mica Powder Play in Coatings?

Mica powder plays multiple important roles in coatings, as follows:

1. Barrier effect

The flaky structure of mica powder can form a basically parallel orientation arrangement in the paint film. This arrangement can effectively prevent the penetration of water and corrosive substances into the paint film, making the diffusion path of these substances in the paint film tortuous, thereby prolonging the time for them to penetrate the paint film, usually by about three times. This barrier effect is crucial for enhancing the performance of anti-corrosion coatings and exterior wall coatings. Meanwhile, mica powder is cheaper than special resins and has higher technical and economic value.

2. Improve the physical and mechanical properties of the paint film

The flaky structure of mica powder is similar to that of sand and gravel in concrete, which can play a reinforcing role and thereby improve a series of physical and mechanical properties of the paint film. For instance, it can enhance the hardness, toughness and adhesion of the paint film, making it more robust and durable.

3. Enhance the anti-wear performance of the paint film

Mica is one of the components of granite and has high hardness and mechanical strength. Therefore, adding mica powder can significantly improve the anti-wear performance of the paint film. This characteristic has enabled mica powder to be widely used in automotive coatings, road surface coatings, mechanical anti-corrosion coatings and wall coatings.

4. Insulation performance

Mica powder has an extremely high electrical resistance (10¹²-10¹⁵ ohms ·cm) and is an excellent insulating material. It can also be compounded with silicone resin or silicone boron resin and transformed into ceramic substances with good mechanical strength and insulating properties at high temperatures. Even if they are burned in a fire, the wires and cables can still remain insulated. This characteristic is of great significance for electrical equipment in places such as mines, tunnels and special buildings.

5. Flame retardant performance

Mica powder is a valuable flame-retardant filler. When combined with organic halogen flame retardants, it can be used to produce flame-retardant and fireproof coatings.

6. Resistance to ultraviolet and infrared rays

Mica powder has an excellent ability to shield ultraviolet and infrared rays. Adding mica powder to outdoor coatings can significantly enhance the UV resistance of the paint film and delay its aging. In addition, the infrared shielding property of mica powder can also be used to formulate thermal insulation and heat preservation materials.

7. Thermal radiation and high-temperature coatings

Mica powder has excellent infrared radiation capabilities. When combined with substances such as iron oxide, it can produce outstanding thermal radiation effects. Therefore, mica powder is widely used in fields such as thermal control coatings for spacecraft and coating for high-temperature facilities.

8. Sound insulation and shock absorption effect

Mica powder can significantly alter the physical modulus of materials, forming or changing their viscoelasticity, thereby efficiently absorbing vibration energy and weakening vibration waves and sound waves. In addition, the repeated reflection of vibration waves and sound waves between mica wafers will further weaken their energy. Therefore, mica powder can be used to formulate sound-absorbing, sound-insulating and shock-absorbing coatings.

9. Reduce sedimentation

The tiny wafers of mica powder can remain suspended in the coating for a long time and are not prone to sedimentation and stratification, thereby enhancing the storage stability of the coating.

10. Gloss effect

Mica powder has excellent pearlescent luster. Large-sized thin flaky mica powder can endow coatings with luster, glittering or reflective effects. On the contrary, extremely fine mica powder can produce a matte effect in coatings.

In conclusion, mica powder has multiple important functions in coatings and can significantly enhance the performance and service life of coatings.