Mica is a highly complex silicate mineral, often in the form of scales, and its main component is alumina containing silicon and potassium, which is flaky and elastic. In the application of coatings, it can increase the toughness of the coating film, reduce cracking, and improve weather resistance, salt resistance, electrical conductivity, and water resistance. Mica powder is primarily used in gypsum-based caulking agents, thick-layer paints, and primers in the paint industry.
(1) Performance of mica powder
Mica powder has high insulation, heat resistance, acid and alkali corrosion resistance, and low thermal expansion coefficient.It is a flake with good elasticity and toughness no matter how broken. Mica powder has better-sliding properties, more substantial coverage, and higher adhesion.
(2) The use of mica powder
The fineness of mica powder varies with different uses and is generally divided into four grades: coarse, medium, refined, and ultrafine. 8~12 mesh mica powder is primarily used in roofing materials such as linoleum and is also used for electric cable wrapping and similar purposes; 40~60 mesh mica powder is used for the coating of welding electrodes; 60~120 mesh mica powder is the primary raw material used to produce mica ceramics; 100 mesh or finer mica powder is used as an admixture of paint, rubber filler, covering agent and lubricant, and plastic filler; 200 mesh and below 325 mesh ultrafine mica powder is used as mica titanium is the base of thepearlescent pigment. Mica powder is also used as a material for sealing well holes when drilling oil wells, as a coating for models when casting metals, as a polishing agent for aluminum products, as a coating for electroplating melting tanks, as a filler in degreasing powder in cosmetics, antifreeze and anti-yang paint pastes. In addition, it can be used as a powder suspension in dry powder fire extinguishers in fire fighting equipment.
Wollastonite powder
Wollastonite is a natural calcium metasilicate mineral that has three homogeneous multi-phase transformations: two low-temperature phase transformations, namely triclinic wollastonite and monoclinic para wollastonite; one high-temperature phase transformation, commonly known as pseudo-wollastonite. The common wollastonite in nature is mainly low-temperature triclinic wollastonite, and the other two-phase transformations are rare.
Natural wollastonite (low-temperature triclinic wollastonite) is usually white to off-white, with glass or pearl luster, density 2.78~2.91g/cm3, hardness 4.5~5, melting point 1544Y, soluble in acid, can be boiled with hydrochloric acid to generate flocculent silica gel. Wollastonite is usually in the form of acicular, radial, and fibrous aggregates, and even tiny particles still maintain a fibrous habit with small thermal expansion, low loss on ignition, and good fluxing properties.
Wollastonite is a contact metamorphic mineral produced in the contact zone between magmatic intrusions and carbonate rocks, formed by the reaction of SiO2 and CaSO3, and can also be formed by regional metamorphism of calcareous rock formations such as limestone and marble.
The main component of wollastonite powder is calcium metasilicate CaSiO3, which is crushed and ground from wollastonite ore. It has a needle-like or fibrous structure. Since the content of SiO2 in wollastonite powder is generally more than 50%, it has high strength. In coatings, needle-like crystals make it an excellent flatting agent and can improve the leveling. Due to its flaky and fibrous structure, which can enhance the coating film’s lubricity, wear and weather resistance, the wollastonite is ground into 1-8 granules and applied to the coating, which can replace part of the titanium dioxide.
Wollastonite powder is used less in dry-mixed mortar and is usually used as a high-grade water-resistant putty for exterior walls. The usage is negligible due to the price factor. However, wollastonite powder’s physical and chemical properties determine that it is a perfect filler. Wollastonite powder is suitable for coatings. It can make white coatings have bright hues and can be used as a flatting, suspending, and reinforcing agent for coatings. Wollastonite powder is used in latex paints and can replace 10% to 40% of titanium dioxide, so Wollastonite powder can be used as part of the white pigment in architectural paints.
