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What is MICA?

Mica is a naturally occurring mineral, based on a group of silicate minerals composed of varying amounts of aluminum, potassium, magnesium, iron and water having thin sheet-like or plate-like structure with different composition and physical properties.

All Mica form flat six-sided monoclinic crystals with a remarkable cleavage in the direction of large surfaces, which permits them to be easily cleaved into optically flat films. When cleaved into thin films, they remain tough and elastic even at high temperatures.

Mica possesses some of the most outstanding combinations of chemical, physical, electrical, thermal and mechanical properties which cannot found in any other insulating product.

Mica is a biaxial birefringent crystal. Its average refractive index in the visible spectrum is about 1.6. Because of its birefringence, it can be used to cause a phase delay between two orthogonal components of an input linear polarization and thus can be used as a retardation device.

About MICA

Types of MICA

Physical Properties

Chemical Composition

MICA Comparison Chart

Technical Data Sheets

Physical Properties

Specific gravity 2.82
Index of refraction 1.58
Hardness (Moh’s scale) 2.5
pH value (BS 3483) 7.7
pH for distilled water 5.2
Oil absorbtion 60-90 g/oil
(BS 3483) 100g Mica
Water Soluble Not more
(BS 1765) than 0.5%
Effect by common acids Slight
Phericity Factor 0.01
Softening point 2800°F

Chemical Composition

Silica (SiO2 ) 45.70%
Alumina (Al2 O3 ) 33.10
Potassium Oxide (k2O) 09.87%
Ferric Oxide (Fe2O3) 02.48%
Sodium Oxide (Na2O) 00.62%
Titanium Oxide (TiO2) Trace
Calcium Oxide (CaO) 00.21%
Magnesia (MgO) 00.38%
Moisture @ 100 °C 00.25%
Phosphorous (P) 00.03%
Sulphur (S) 00.01%
Graphitic Carbon (C) 00.44%
Loss on ignition (H2O) 02.74%

MICA Comparison Chart

PropertiesUnitsMuscovite Phlogopite
Color Ruby/ Green/ WhiteAmber/ Silver/Green
Densitygm/cm32.6 – 3.22.6 – 3.2
Specific heat 0.210.20
HardnessMoh scale2.8 – 3.22.3 – 3.0
 Shore Test80-10570-100
Breakdown voltageKV/mm120 – 200
Coefficient of expansion per  °C perpendicular to cleavage plane 9 x 10-6 – 36 x 10-630 x 10-6 – 60 x 10-6
Thermal conductivity perpendicular to cleavage planeGm.cal/sec/cm2/°C/cmabout 0.0013about 0.0010
 BTU/hr/ft2/0f/ftabout 0.31about 0.24
Thermal conductivity parallel to cleavage planeGm.cal/sec/cm2/°C/cm about 0.012
 BTU/hr/ft2/0f/ft about 3.0
Water of Constitution % 4.53.0
Moisture Absorption Very lowVery low
Volume Resistivity25°C (77°F) ohm cm40 x 1013 -2 x 10171 x 1012 -1 x 1012
Acid Reaction affected by hydrofluoric acidaffected by sulphuric acid
Insulation resistencex1013ohm/cm4-200000.1 – 10
Calcining temp°C700-800900-1000
Max. operating temp°C500-600800-1000
Optic axial angledegrees55 – 755 -25
Tensile strengthMN/m21751000
Shear strengthMN/m2220 – 2701000-1300
Compression strengthMN/m2190 – 285
Modulus of ElasticityKgfcm2 x 10-3
lbf/in2 x 10-6
1400 – 2100
20 – 30
1400 – 2100
20 – 30
Loss tangentx10-41-410-50
Permittivity at 15°C (60°F) 6 – 75 -6

Technical Data Sheets

Technical Data Sheets are available for each Mica product.

Please contact us at (516) 248-0045 or info@aximmica.com for this information.

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