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Introduction to Mica

Dec. 02, 2020


Mica is the most widely distributed rock-forming mineral and the general term for layered aluminum silicate. The types of mica mainly include muscovite, Phlogopite, sericite, biotite and lepidolite. Among them, sericite, muscovite and phlogopite are commonly used in the plastics industry. Lepidolite is a mineral raw material for extracting lithium.


Sericite


Sericite is a natural fine-grained muscovite, a subspecies of muscovite, and a layered silicate mineral. The structure is composed of two layers of silicon-oxygen tetrahedrons sandwiching a layer of aluminum-oxygen octahedrons. composition. Sericite has complete cleavage and can be split into extremely thin flakes with a thickness of less than 1μm (theoretically can be cut to 0.001μm) and a large diameter-to-thickness ratio; compared with muscovite, it has a small natural particle size and is easy to exceed Features of fine processing.


Sericite has a Mohs hardness of 2 to 3, a specific gravity of 2.7 to 3.2, and a pH of 6 to 8. The refractive index increases with the increase of iron content. Variants without iron, colorless in the flakes, the higher the iron content, the darker the color. Sericite has an excellent shielding effect on ultraviolet rays, the appearance is silky luster, and the hand feels fine and smooth. Sericite powder has unique acid resistance, alkali resistance, chemical stability, and also has good insulation, heat resistance, non-combustibility, and corrosion resistance.


Phlogopite

Phlogopite


Sericite has a wide range of uses in plastics with its unique two-dimensional flake structure and excellent performance of combining rigidity and flexibility. Its excellent performance is shown in: it can reduce the shrinkage, warpage, curvature and specific gravity of the product, and improve the machinery of the product. Performance, heat resistance, heat resistance, chemical stability and barrier properties, increase the surface gloss and weather resistance of products; when used in plastic food containers and electronic cookers, it can improve the microwave permeability of products. At present, sericite is mainly used in PP, thermoplastic polyester, PC, PE, polymethylpentene, PA, unsaturated polyester, phenolic plastic, PU, etc.


Muscovite and Phlogopite


Muscovite has a glass luster, generally colorless and transparent; Phlogopite has metallic luster and semi-metallic luster, common golden yellow, brown, light green, etc., with poor transparency. Muscovite and phlogopite have good electrical and mechanical properties, good heat resistance, chemical stability and corona resistance. Both types of mica can be peeled and processed into soft and elastic flakes with a thickness of 0.01 to 0.03 mm. The electrical properties of Muscovite Powder are better than phlogopite, but phlogopite is softer and has better heat resistance than muscovite. The most used in industry is muscovite, followed by phlogopite. It is widely used in building materials industry, fire fighting industry, fire extinguishing agent, welding rod, plastic, electrical insulation, papermaking, asphalt paper, rubber, pearlescent pigment and other chemical industries.


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