Detail：

Features & Applications of Mica

Ⅰ. Brief Introduction

Mica is the generic name of the layer-structured aluminum-silicate, which consists of potassium, magnesium, aluminum, iron, lithium. It usually appears in six-square like or diamond-shaped columnar crystal, shaped in plate or sheet.

According to the differences of its chemical elements and optical characteristics, we can classify mica ore into three categories: muscovite-sericites type, phlogopite-biotite type and lithionite-lepidomelane type. The most common minerals in the mica group are: muscovite, sericite, biotite, phlogopite and lithionite.

Muscovite looks in transparent or in light color, while biotite shows in black, dark brown, or dark green. Phlogopite looks in gold, brown, dark green or transparent, while lithionite shows in light purple, rose pink or grey.

 Technical Requirements：

 

 

 

Chemical Elements

components	SiO2	Al2O3	K2O	MgO	H2O	Na、Ti、Mn、Fe、F
content（%）	38.7-45	10.8-17	7-10.3	21.4-29.4	<1	A few

Physical Properties:

 

 

 

1.    Physical & Chemical Properties：

Mica has the gloss of glass; its cleavage surface shows pearly luster. Its Mons’ hardness scale is 2-3.5, and proportion is 2.7-3.5.  The color of mica changes according to its chemical elements, if it contains chromium, it shows in green, while contains lithium, shows in rose pink.

2.    Optical Properties

The thickness of mica ’s pairs of reflecting surfaces is only one fourth of the wavelength of UV light, which causes mutual interference when UV light getting through mica, therefore, mica can block the UV light. Additionally, the layer of mica’s directional distribution made it has excellent lightproof performance.

3.    Electrical Properties

insulation strength：159-317kV/mm

resistivity：1014-1015 Ω·cm

surface resistivity：1011-1012Ω·cm

dielectric loss angle：tan δ=0.001-0.08（50Hz）

The prominent property of mica is its dielectric insulation. The performance of its insulating property, which decides mica playing an important role in electric industry. 

4.Heat Resistance & Stability

When heated up to 100-600 ℃,the elasticity and surface features of muscovite will not be affected.  After being heated up to 700-800℃, muscovite will get dehydrated and crispy, the dielectric performance will be changed; while heated up to 1050℃, its structure will get damaged.

Phlogopite has a better dielectric performance than muscovite during the temperature 700℃.

Mica will not affect to acid-alkali in room temperature, even will melt in high acid liquids. But it will get decomposed in boiling acid liquids over a long period of time.

 Ⅱ. Characteristics of Mica:

Mica, with the characteristics of high electrical insulation, which can endure high temperature and its dramatic changes, also maintains the feature of anti-acid & alkali corrosion, elasticity & toughness, processes excellent heat & sound insulation and low thermal conductivity.

Based on the unique features above, mica is wildly applied to the wireless industry, aviation, motor manufacturing, building materials & paints, fire-fighting & fire extinguisher, welding rods industries, also used in chemical industries such as, plastics, ceramics, dielectrics, paper-making, asphalt paper, cosmetics and pearlescent pigment etc.

Processed mica powder possesses good flowability & absorbability. The most widely-used mica is muscovite and followed with the phlogopite in current industry. 

 Ⅲ. The Current Applications of Mica

1. On Insolation Materials

Mica played an important role in electric industry for its good dielectric properties since 19th century. Especially in the field of dielectric material, electric motor manufacturing, electric capacitor, potting material, fireproof cable, mica goods and fine ceramics.

 2. On Plastics Industry

Mica powder used as enhanced fillings for mica sheet, which can enhance the property of mica sheet, improve the slice mica’s high diameter/thickness ratio, strengthen the tensile & bending strength of plastic, stabilize plastic’s shape, enhance its creep resistance and flatness, decrease deformation under high temperature, prevent plastic’s curling, block the permeation of liquid & gas, improve the electric insulation of plastics. 

 3.On Paper-making Industry

Mica is an excellent filling material in paper-making industry. The paper added the mica powder, has features of brighter in color, higher UV resistance, less yellowing in long preservation, not easy to crack, better smoothness & tightness.

Coated paper, added with mica powder, has better degree of whiteness, smoothness, ink glossiness than clay coated paper.

 4.On Coatings Industry

When mica powder added in coatings, it can improve coatings’ abilities of dispersion, heat & frost resistance, water resistance, making coating processing more smooth.

The mica powder can reflect the UV light, and absorb ions of pigment into crystal lattice layer, therefor, construction coating materials, which filled with mica powder, will not fade in color.

 5. On Paints Industry

When paints added with mica powder, enhanced paint’s wash ability, adhesion, corrosion resistance, which can extend the life span of outer layer of the paint.

Mica powder can replace the relatively expensive titanium dioxide partly or fully, which can reduce the costs of paint products, improve economic efficiency. In addition, mica powder can block the subsidence of pigment in container during preservation, it can also make the mixture well done in pigment application.

 6. On Ceramics

Mica is an important raw material for ceramic industry, melting in low temperature that helps to reduce the ceramic burning temperature. Mica’s hardness is lower than quartz and feldspar, which can reduce energy consumption in raw material crushing and grinding, thus, making the cost down and resource saving. Mica can easily response with glaze, which can improve the quality of ceramic products.

 7. On Cosmetics Field

Fine grinding mica powder has features of good dispersity, delicate texture, elasticity, high whiteness, nontoxic, it also has beautiful luster, and can well mixed with water and glycerol, therefore, it becomes the best choice for cream, ointment frost and powder’s fillings.

Especially sunscreen added with mica powder, can enhance UV resistance of sunscreen due to the unique flaky structure of mica.

 8. On Building Materials

Mica powder replaced asbestos in plaster board’s cementing material, not only decreasing the pollutions, meeting current people’s needs for environment protection, but also increasing plaster board’s extensity & color, improving the sliding operation performance, moreover, decreasing gypsum’s cracking.

In addition, mica powder is the important cementing material for cement board, it can also have applied for shipbuilding composite plate, such as calcium silicate refractory plate.

 9. Others Fields

Pearlescent pigment added with mica powder, compares with basic lead carbonate pigment, it has features of lighter proportion, easier to disperse, nontoxic and more stabilize in performance. Consequently, Pearlescent pigment has already replaced the basic lead carbonated pigment, and been widely used in food container, children’s toy and cosmetics fields.

The double-layered burned composite material, which been mixed with mica powder and glass powder, possesses features of warm preservation, sound insulation and high intensity, becoming a new economical material in modern construction.

Mica added spraying material can strengthen shock absorbing, which bring new thoughts for high-end steel plate.