Mica is a kind of layer silicate mineral containing water with a great variety. Mica powder has unique acid resistance, alkali resistance, and chemical stability, as well as good insulation, heat resistance, noninflammability, and corrosion resistance.
Mica is divided into white mica, flogopite, sericite, biotite, and so on. According to the processing degree, it can be divided into mica flakes and mica powder. White mica is most commonly used in industry, followed by flogopite. The molecular formula of white mica is K2O·3Al2O3·6SiO2·2H2O, and the relative density is 2.8- 3.2. Mica powder is in the shape of a thin flake with the general particle size of 10 - 80um and the length-width ratio of 30. It is mainly used as an insulating material for electrical equipment and electrical equipment because of its insulativity, heat resistance, acidoresistance, alkali resistance, crushing resistance, and dispersity. Mica powder is also widely used in coating, rubber, plastics, and other industries as fillers and building materials. Flake mica can be used in reactive injection molding (RIM) polyurethane as a reinforcing filler to achieve some strengthening effects.
Mica powder belongs to monoclinic crystals, and the crystal is flaky with silk luster (white mica shows glass luster) and pure mica blocks are gray, purple roseal, white, etc.. The radius-thickness ratio of mica powder is more than 80, the specific gravity is 2.6-2.7 and the hardness is 2-3, besides it has good elasticity, bendability, wearing quality, and abrasive resistance; with stable chemical properties, it is heat - resistant, insulating and insoluble in acid-alkali solution. Test data show that the elastic modulus is 1505-2134mpa, heat resistance is 500-600℃, thermal conductivity is 0.419-0.670W.(M.K.)-1, electrical insulation is 200kV /mm and radioactivity resistance is 5×1014 thermal neutron /cm2 illumination. In addition, mica powder is similar to kaolin in chemical composition, structure, and tectonics, and has some characteristics of clay minerals such as good dispersibility and suspension property in water medium and organic solvent, fine and white appearance as well as viscosity. Therefore, mica powder has many characteristics of mica minerals and clay minerals.
It is easy to identify mica powder. According to experience, there are roughly the following methods for your reference:
First of all, the whiteness of mica powder is not high, which is about 75. Customers often question and reflect that the whiteness of mica powder is about 90, but generally, its whiteness is not high, which is commonly only about 75. If doped with other fillers such as calcium carbonate, talc powder, the whiteness will be greatly improved.
Second, mica powder is of flake structure. Add 100ml pure water in a beaker, and stir it with a glass rod. It can be seen that mica powder has good suspension property. The suspension property of other fillers such as transparent powder, talcum powder, and calcium carbonate is not as good as mica powder.
Third, besmear a little mica powder to the wrist, and it will show some pearl luster effects; Mica powder, especially sericite powder, has a certain pearl luster effect and is widely used in cosmetics, coatings, plastics, rubber, and other industries. Customers should pay attention If the purchased mica powder has poor or even no pearl luster effect.
