1. Overview of sericite
Is a collection of fine-grained sericite minerals mica format (Mineralogical Association World - International Mineralogical Association). We Mineral heading alumosilicat with typical characteristic is the subclass, should be separated into thin layers, the thickness may reach 1 nm (Figure 1.1). General chemical formula for the mineral groups are: (K, Na, Ca) (Al, Fe, Mg) 2 (Si, Al) 4O10 (OH) 2.

The chemical composition of single mineral is SiO2 = 43-49% sericite, Al2O3 = 27-37%, 9-11% K2O + Na2O =, H2O = 4-6%. The chemical composition of sericite this change in each field depending on the mineral composition and composition of chemical elements involved mineral structure.
Sericite be white, pink, light gray, yellow or brown; mine; transparent to translucent. Often confused with kaolinite sericite; however, may be based on the characteristics of sericite to feel slippery as hand strokes on similar characteristics talc and light silk sericite and kaolinite to distinguish. Moderate sericite mica bearing features, both characteristic of clay minerals. Sericite there are specific physical properties as follows:
- Fines - very smooth; stool thin sheets - very thin; rate surface diameter / thickness> 80;
- Density: ~ 2.8; Hardness: 2.0-3.0 (Mosh scale);
- High elasticity, ductile (coefficient of elasticity: 1505-2134 MPa), smooth surface, good abrasion resistance.
- High heat resistant (refractory limit: 500-600 OC [9]); low thermal conductivity (heat conductivity coefficient: 0.42 to 0.67 W / (mK); heat capacity of 0.8 kJ / kg.K; good insulation (electric reliability 200 kV / mm; resistor: 92 , 6 MOhm / cm), soundproof, waterproof ...
- Sustainable chemistry, hardly destroyed in acid and alkali solution;
- Dispersion in water and in organic solvents, high viscosity;
- Reflection and refraction good; potentially prevent ultraviolet (UV).

2. The field of use of sericite

With many chemical properties - offers Vietnamese reason as above, together with the quality and reasonable prices, sericite is used in many sectors and different areas. Depending on the composition and needs, sericite is used as the main raw material, additives, fillers, coatings or bulking agents.
- Industry paint and coating materials
Sericite and mica is used as a bulking agent, increases the slurry, surface adhesion, prevent shrinkage phenomena and surface deformation, increase the tolerance to the impact weather , ultraviolet rays and reduces the possibility of surface water repellent paint, surface coating materials. The application of sericite coating materials including architectural coatings, anti-corrosion coatings, powder coatings, fire retardant paint, insulation coatings, traffic paint, marine paint, paint radiation protection and functional coatings other. Also, with characteristic luster of silk and high fineness, sericite is considered indispensable quality in industrial paints with high quality. Products such as cars, motorcycles ... sericite paints are superior gloss and luster of pearls sparkle. Also, in the manufacture of paints, sericite used to replace TiO2, lowering product costs.
The quality requirements for paint with sericite as follows: Chemical composition: content (%) SiO2: 58-68; Al2O3: 15-18; Fe2O3: 1.2 to 2; K2O: 5-6; pH: 6.8; H2O: ≤ 1.5. Whiteness 70-80. Particle size: 325 mesh sieve.
- Paper Industry
In the paper industry, sericite can be used as fillers, increasing the stability of the reaction system and increase retention of fine particles and chemicals. Therefore, performance products, thickness, air permeability and smoothness of paper are increased. With the objective of producing all kinds of white paper or colored paper of high quality, shiny, people often have to handle delamination kaolin, zeolites to turn them into surface materials. However, research also shows that, can replace partially or totally peeled kaolin by sericite.
- Rubber Industry
Rubber industry use as fillers and sericite-stick mold during the production of molded rubber products such as tires and roofing. With crystal structure plate, sericite acts as a lubricating agent and anti-adhesive. Sericite also with enhanced bearing durability of rubber products like powdered carbon black (amorphous carbon forms) and white charcoal powder (powdered silicon tetrachloride); rubber for bright, sericite may replace 5-30% white charcoal powder. In rubber products, sericite also increased elasticity, anti-aging, anti-crack, high strength reinforcement, increased chemical resistance, reduced air infiltration, increase the heat resistance ... Sericite also used use of roll roofing production (oil paper) and asphalt visor as surface coatings for non-stick, increased durability in weathering conditions and not affected by the acid in the asphalt.
- Industrial Polymers
In its role as a filler and swelling agent, sericite is used in industrial production of polymers, including all kinds of hard and soft thermoplastic (nylon, polythene, polypropylene, polyester ...) and thermoplastic (phenol formaldehyde, epoxy ...). Specifically, sericite plastics used for automotive use for soundproofing, insulation and reduce collisions. Sericite also be used as a reinforcing material in some detail cars like dashboard and fenders, to increase mechanical strength, stiffness, and stability of size. Plastics containing sericite size stability even at high temperatures, and have the best surface properties.
- Industrial ceramics
From the early 17th century, schist - sericite were used as raw materials for manufacturing ceramics, sanitary ware. In ceramics, sericite ore bauxite is used as a raw bone and enamel coordination with the utilization rate of 15 ÷ 20% in bone and 5 ÷ 7% in men. Sericite works to enhance the rustic and intensity of the porcelain after firing. Sericite ore quality requirements for ceramics: Al2O3 ≥ 13%; ˃ 3.5% K2O; ˂ 0.5% TiO2; ˂ 1% Fe2O3.
Sericite increase the brightness, thermal stability and electrical insulation for ceramic.
- Production of welding electrodes
In producing welding rod can be used to replace a portion sepiolit sericite, kaolin, pyrophyllit to shell welding rod. Compared with sepiolite, kaolin, pyrophyllite, sericite rich in K2O (pyrophyllit: 7.41%, Sericite mica: 7.5 to 11%, kaolin, sepiolit, not containing K2O), so it has a lower ionization energy When the electrode is burned, it is ionized to provide the ion conductivity and makes the arc stable fire.
Sericite contain less S, P and impurities (S: 0.015 to 0.018%), it tends to reduce the amount of S, P in the metal, reduces the likelihood of cracking metal and increased resistance of the weld cracking . Sericite have flexibility, dexterity, can increase the activity of the coating of welding rods and improve its ability to squeeze government.
Sericite have relatively uniform grain size, no oversize particles, when the arc of fire no explosion occurs, so reducing vibration and sound when welding.
Sericite can increase smoothness and adhesion of the coating, can be substituted for the titanium dioxide (TiO2) and reduce production costs. Mixing ratio is 3% to 5% when used in the production of welding electrodes E4303, E4313. The quality requirements for the production of welding electrodes sericite: Al2O3 ≥ 22 ÷ 33%; ˃ K2O 6.7%; P ˂ 0.045%; SiO2 = 47 ÷ 60%; S0,02%; particle size of 0.075 mm.
- Building materials, mud
During drilling construction industry, sericite can be used as an additive in drilling mud. Because components of bentonite drilling mud is very smooth, so the more coarse sericite cotton can help clogs the pores of the drill hole, preventing the loss of inter drilling fluids. However, drilling mud used just under 1% sericite. Sericite is also used in concrete, plaster, cement, artificial stone production paving ...
- Chemical industry and cosmetics
With its low hardness, crystalline structure and lamellar refractive index high, pure sericite type, white and smooth (mm grain size) is the most potential for application in cosmetics. Sericite is a key ingredient in many products such as blusher eyeliner, eye shadow powder, foundation, lipstick, lip gloss, mascara, moisturizer, nail polish ...
- Other applications
Sericite can also be used in the manufacture of some special lubricants, surface coating, coating materials for core and non-stick material in the smelting molds, UV glasses ...