Muscovite and Phlogopite Mica Sheet
Mica
Mica is a naturally occurring mineral insulator offering exceptional dielectric strength, heat resistance, and dimensional stability. We supply muscovite and phlogopite mica sheet, tape, and die-cut parts for electrical insulation, high-temperature gaskets, and thermal barriers in power generation, furnace, and switchgear applications.
At a Glance
Temperature Range
Natural muscovite to 600 °C continuous; natural phlogopite to 800 °C continuous (900 °C intermittent for splittings only); silicone-bonded sheet to 500 °C; epoxy-bonded sheet to 180 °C; synthetic fluorophlogopite to 1100 °C continuous
Thickness Range
0.1 mm to 3 mm
Available Forms
Colours
Technical Properties
Typical values across stocked grades. Specific grade data sheets available on request.
Physical Characteristics
Density
2.6–3.0 g/cm³
Tensile Strength
150–250 MPa (natural crystal, parallel to layers; bonded sheet grades lower)
Dielectric Strength
20–40 kV/mm (ASTM D149)
Chemical Resistance
Resistant To
- Water and steam
- Most organic solvents
- Mineral oils and transformer oils
- Dilute acids
- Silicone oils and greases
Limited Resistance
- Concentrated sulphuric acid at elevated temperature
- Strong alkalis at high concentration
Not Recommended
- Hydrofluoric acid (attacks the silicate structure). Use PTFE instead.
- Concentrated sodium hydroxide at high temperature, which causes delamination
- High-pressure steam above service temperature, where moisture absorption weakens dielectric properties
Environmental Ratings
Flame Rating
Non-combustible. Natural mica does not ignite or support flame (resin-bonded grades limited by binder).
Weather Resistance
Good. Moisture absorption is low, though sealing edges is recommended for outdoor use.
Standards & Certifications
Standards Compliance
Common Applications
- Electrical insulation in switchgear and transformers
- High-voltage bushing and commutator insulation
- Furnace observation window gaskets
- Thermal barrier sheets in heating elements
- Insulating washers and spacers in electrical assemblies
- Fire barrier and flame protection sheets
- Microwave oven waveguide covers
- Arc-resistant insulation in motor and generator windings
Not Recommended For
- Brittle and delaminates under impact or sharp bending. Handle with care, and avoid dynamic or vibrating applications
- Not a gasket material for pressure sealing. Mica is used for electrical and thermal insulation, not fluid containment
- Moisture absorption degrades dielectric properties, so seal edges in humid environments or use resin-bonded grades
- Attacked by hydrofluoric acid and strong alkalis; check the chemical environment before specifying
- Natural muscovite splittings are limited to 600 °C continuous; silicone-bonded muscovite sheet caps at 500 °C (binder limit). For higher temperatures use phlogopite splittings, synthetic fluorophlogopite, or ceramic fibre
Available Grades
Muscovite Mica Splittings
Clear to amber natural mica (KAl₂(AlSi₃O₁₀)(OH)₂) with strong dielectric strength. Continuous service to 600 °C. Suited to electrical insulation in switchgear, transformer commutator segments, and high-voltage capacitor dielectrics.
Phlogopite Mica Splittings
Dark amber-brown natural mica (KMg₃(AlSi₃O₁₀)(OH)₂) with higher temperature resistance than muscovite — 800 °C continuous, 900 °C short-duration peak (dehydroxylation onset; natural splittings only). Preferred for furnace, kiln, and arc-resistant insulation where muscovite's temperature limit is exceeded.
Synthetic Fluorophlogopite Mica
Synthetic mica (KMg₃(AlSi₃O₁₀)F₂) with fluorine substituted for hydroxyl groups, eliminating dehydroxylation and extending continuous service to 1000–1100 °C. Used in extreme high-temperature electrical insulation and refractory glazing where natural mica is not adequate.
Resin-Bonded Mica (Micanite)
Mica flakes bonded with epoxy or silicone resin for improved mechanical strength and moisture resistance. Temperature is limited by the binder, typically 180 °C (epoxy) or 500 °C (silicone resin). Available in rigid sheet and flexible tape forms.
Related Materials
Need Mica?
We supply mica in sheet, roll, and custom die-cut forms. Contact our team for pricing, data sheets, or technical assistance.
Disclaimer
This resource is provided for general engineering reference only and does not constitute professional advice, specification, or guarantee of performance. Actual results depend on specific application conditions. Universal Gaskets Pty Ltd accepts no responsibility or liability for decisions made based on this information. For full terms, see our Terms & Conditions.