MICA SHEETS
Rigid Mica Sheets: Thermal & Electrical Insulation
PRODUCTS > MICA SHEETS
WHAT ARE MICA SHEETS?
Mica sheets are the foundation for manufacturing various mica parts used in thermal, electrical, and mechanical insulation applications. The appropriate material of the mica sheet, either Muscovite or Phlogopite, depends on the specific requirements of your application. Muscovite mica offers excellent dielectric strength and is ideal for lower-temperature applications, while Phlogopite provides superior thermal resistance, making it suitable for high temperature environments up to 1000°C.
The level of heat resistance needed will also determine the thickness of mica sheet. Thicker mica sheets will provide better thermal insulation and structural integrity. Mica sheets are not uniform; they can be ordered in various sizes, thicknesses, and different degrees of smoothness to meet your specific needs. In addition to excellent thermal and electrical insulation properties, mica sheets are flame-resistant, chemically stable, and non-toxic, making them ideal for industries such as electronics, automotive, aerospace, and household appliances. At Axim Mica, we customize our sheets to meet your exact performance needs.
APPLICATIONS
Axim’s mica sheets are renowned for their versatility and durability in applications that require electrical and thermal insulation. It offers exceptional electrical properties, high heat resistance, and notable chemical stability that makes it an indispensable material.
AX-THERM Muscovite & Phlogopite mica sheets are used in a broad range of applications such as:
Heating elements for electrical and thermos-mechanical equipment.
Construction of induction, arc, or high frequency furnaces.
High voltage and high thermal applications.
Industrial sealing and gasket industries (e.g. oil and gas distribution).
AX-THERM M & P mica sheets are also the ideal alternative for asbestos insulation due to:
- Good resistance to high temperature and chemicals
- Low heat conductivity
- High dielectric strength
- High-voltage performance
- Fire resistance classification: UL94 (94 V-0), BS 479 (CLASS 1), NBN 21-203 (A1)
COMPOSITION & COMPARISON OF AX-THERM MUSCOVITE & PHLOGOPITE
Mica sheets are composed primarily of the mineral mica, which consists of aluminum silicate along with other elements such as potassium, iron, magnesium, and water.
Our AX-THERM Muscovite & Phlogopite mica sheets consist of 85-90% high-grade Muscovite or Phlogopite that is impregnated with a high temperature resistant silicone resin.
| Technical Data | Muscovite | Phlogopite |
| Mica Content: (IEC 60371-2) | 85 – 90 % | 85 – 90 % |
| Silicone Binder Content: (IEC 60371-2) | 10 – 15 % | 10 – 15 % |
| Density: (IEC 60371-2) | 2,2 – 2,3 g/cm³ | 2,2 – 2,3 g/cm³ |
| Heat Resistance: | In Continuous Service: 500 °C In Intermittent Service: 800 °C | In Continuous Service: 700 °C In Intermittent Service: 1.000 °C |
| Tensile Strength: (ISO 527) | 150 N/mm² | 110 N/mm² |
| Bending Strength: (ISO 178) | 230 N/mm² | 170 N/mm² |
| Water Absorption: | <1 % (24h/23°C) | <1 % (24h/23°C) |
| Dielectric Strength: (IEC 60243) | at 20°C: 25 KV/mm at 400°C: 13 KV/mm at 600°C: 10 KV/mm | at 20°C: 25 KV/mm at 400°C: 13 KV/mm at 600°C: 10 KV/mm |
| Volume Resistivity: (IEC 60093) | at 20°C: >1016 Ω/cm >1016 Ω/cm at 400°C: >1012 Ω/cm >1012 Ω/cm at 500°C: >109 Ω/cm >109 Ω/cm | at 20°C: >1016 Ω/cm at 400°C: >1012 Ω/cm at 500°C: >109 Ω/cm |
| Weight Loss Continuous: (IEC 60371-2) | at 500°C: <1 % | at 500°C: <1 % at 700°C: <2 % |
| Thermal Conductivity: | Perpendicular to Plane of the Plate: 0,3 W/mK 0,3 W/mK Along the Plane of the Plate: 3,0 W/mK 3,0 W/mK | Perpendicular to Plane of the Plate: 0,3 W/mK Along the Plane of the Plate: 3,0 W/mK |
| Thermal Expansion: | Perpendicular: 100 x 10-6 /°K Parallel: 10 x 10-6 /°K | Perpendicular: 100 x 10-6 /°K Parallel: 10 x 10-6 /°K |
SUPPLY FORM
At Axim Mica, we offer a broad range of size and thickness to fit any application:
Thickness: 0.1mm – 101.6mm (tolerances: 2-5mm +/- 7% | 5-30mm +/- 5% | 30-80mm +/- 3%)
Sizes: 1000mm widths, max. 2400mm lengths
New Option: Ultra Smooth Surface or De-Smoked Mica Sheets
Customized strips or parts according to customers’ drawings and/or requirements
ENGINEERING EXCELLENCE WITH AXIM MICA
Ready to move forward? Partner with us to leverage the full potential of our AX-THERM mica sheets. Our engineering team collaborates with clients to develop optimal solutions for their specific applications, ensuring every component meets exact specifications and performance requirements.
Table of Contents
SECTION 2: TYPES AND PROPERTIES OF MICA SHEETS
8. What is the difference between muscovite and phlogopite mica?
9. Which mich is better suited for higher temperatures?
10. What does ‘dielectric strength’ mean?
11. Are mica sheets flexible?
12. How thick are standard mica sheets?
13. Can mica sheets be transparent?
SECTION 3: PRACTICAL APPLICATIONS AND INDUSTRIES
14. Where are mica sheets used in electronics?
15. Why is mica used in heating elements?
16. What is the role of mica in the automotive industry?
17. Are mica sheets used in construction?
18. Can mica be used for arts and crafts?
19. Is mica used in cosmetics?
SECTION 4: SELECTION AND HANDLING GUIDELINES
20. How do I choose the right mica sheet for my project?
21. What is the best way to cut mica sheets?
22. How should I store unused mica sheets?
23. Can mica sheets be glued or bonded?
24. What are the signs of a failing mica insulator?
25. Is the mica industry ethical?
Frequently Asked Questions
Section 1: Understanding Mica Fundamentals
FAQ 1: What are mica sheets?
Mica sheets are thin, flat pieces of a naturally occurring silicate mineral prized for their outstanding electrical and thermal insulation properties. They are created by cleaving or splitting raw mica blocks into their distinct layers. This process leverages mica’s unique basal cleavage, allowing it to be separated into sheets that are extremely thin, often less than a millimeter. These sheets are then processed for use in a vast range of industrial and consumer products.
Real Results: In a manufacturing setting, using a 0.5mm mica sheet as a barrier allowed a heating element to operate 150°C hotter without damaging adjacent electronic components.
Takeaway: View mica sheets as nature’s high-performance insulators, providing a unique combination of heat resistance and electrical isolation in a thin form factor.
FAQ 2: How are mica sheets made?
Mica sheets are produced by mining raw mica blocks and then manually or mechanically splitting them along their natural cleavage planes into thin laminae. This initial process, called cleaving or rifting, is possible due to the mineral’s layered crystal structure. These thin films are then graded, trimmed, and sometimes bonded with resins to create larger, more rigid composite plates known as ‘micanite.’ The final product is a durable sheet ready for stamping, cutting, and shaping for specific applications.
Real Results: A factory transitioned from manual to automated cleaving, increasing its output of usable 10x10cm mica films by 300% per hour.
Takeaway: The production of mica sheets relies on carefully splitting the raw mineral into its fundamental layers before processing them into usable formats.
FAQ 3: Is mica a natural or synthetic material?
Mica is a completely natural material. It is a group of silicate minerals that form in igneous and metamorphic rocks over millions of years under intense heat and pressure. While there are synthetic versions of mica created in labs for specialized applications like cosmetics, the vast majority of mica sheets used for industrial insulation are mined directly from the earth. This natural origin is key to its unique combination of properties.
Real Results: Geological surveys identified a new deposit of muscovite mica in Brazil, estimated to yield over 50,000 metric tons of high-quality raw mineral.
Takeaway: Always remember that industrial-grade mica sheets are derived from a mined mineral, making their origin and sourcing important factors.
FAQ 4: Why is mica a good insulator?
Mica is an excellent insulator due to its stable crystalline structure, which resists the flow of both electricity and heat. Its high dielectric strength means it can withstand very high voltages without breaking down, preventing electrical arcing. Concurrently, it has low thermal conductivity, meaning it transfers heat poorly, allowing it to act as an effective thermal barrier. This dual-insulating capability is rare and makes mica invaluable in applications where both electrical and thermal stresses are present.
Real Results: A high-voltage capacitor insulated with mica withstood a 5,000-volt surge test, while a similar unit with a polymer insulator failed at 3,000 volts.
Takeaway: Mica’s power as an insulator comes from its dual resistance to both electrical current and heat flow, a property few materials possess.
FAQ 5: Why does mica come in thin layers?
Mica’s layered structure is a direct result of its atomic arrangement, a property known as perfect basal cleavage. The atoms within each layer are strongly bonded, but the bonds between the layers themselves are very weak. This allows the mineral to be easily split or cleaved into incredibly thin sheets, like separating pages in a book. This natural characteristic is precisely what makes it possible to produce the versatile, flexible sheets used in industry.
Real Results: Using a simple knife, a geologist was able to split a single 1cm mica crystal into over one hundred separate, transparent sheets.
Takeaway: The iconic thin layers of mica are not a manufacturing choice but a fundamental property of the mineral’s weak intermolecular bonds.
FAQ 6: Are mica sheets toxic?
Solid mica sheets in their final manufactured form are generally considered non-toxic and inert. They are stable and do not release harmful substances under normal use, including at high temperatures. However, the primary health concern is related to the inhalation of fine mica dust during mining, processing, or machining. This dust can lead to respiratory issues, so proper ventilation and personal protective equipment (PPE) are essential for anyone cutting or sanding mica materials.
Real Results: An industrial hygiene report showed that implementing dust collection systems during mica stamping reduced airborne particulates by 95%, meeting safety standards.
Takeaway: The finished mica sheet is safe, but always use respiratory protection when cutting or sanding it to avoid inhaling fine dust particles.
FAQ 7: What is the history of mica usage?
Mica has been used by humans for thousands of years, initially for its decorative shimmer in prehistoric cave paintings and pottery. In ancient Rome, India, and China, powdered mica was used for decoration, and larger sheets served as primitive window panes, known as ‘Muscovy glass.’ Its modern industrial importance exploded in the late 19th and early 20th centuries with the advent of electricity. Mica’s unique insulating properties also made it a critical component in early electrical equipment, like radios to motors.
Real Results: Archaeologists discovered 2,000-year-old ceremonial artifacts in Ohio decorated with intricate cutouts of shimmering mica sheets.
Takeaway: Mica’s journey from ancient decoration to a cornerstone of modern electronics highlights its timeless and versatile properties.
Section 2: Types and Properties of Mica Sheets
FAQ 8: What is the difference between muscovite and phlogopite mica?
The primary difference between muscovite and phlogopite mica lies in their chemical composition and resulting properties. Muscovite (potassium aluminum silicate) generally has superior dielectric strength, making it the preferred choice for electrical insulation in applications like capacitors. Phlogopite (potassium magnesium aluminum silicate) has lower dielectric strength but can withstand significantly higher temperatures, making it ideal for thermal insulation in furnaces and heating elements. Think of muscovite as the electrical specialist and phlogopite as the heat specialist.
Real Results: A furnace manufacturer switched from muscovite to phlogopite mica for its heating element supports, increasing the element’s maximum stable operating temperature from 600°C to 850°C.
Takeaway: Choose muscovite for high-voltage electrical insulation and phlogopite for extreme high-temperature thermal barriers.
FAQ 9: Which type of mica is best for high temperatures?
Phlogopite mica is the best type for high-temperature applications. It can typically withstand continuous temperatures up to 900°C (around 1650°F), significantly higher than muscovite mica’s limit of about 550°C. This superior thermal resistance is due to its magnesium-rich chemical structure. This makes phlogopite the go-to material for gaskets, furnace linings, and insulators that are in direct contact with or close proximity to industrial heating elements.
Real Results: An industrial foundry uses 2mm thick phlogopite sheets to line its crucible holders, successfully containing heat that reaches 800°C daily.
Takeaway: When your primary concern is heat resistance above 600°C, phlogopite is the unequivocal choice over muscovite.
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FAQ 10: What does ‘dielectric strength’ mean?
Dielectric strength measures a material’s ability to act as an electrical insulator, specifically its capacity to withstand high voltage without failing. For mica, it is typically expressed in volts per mil (one-thousandth of an inch) and signifies the maximum voltage a sheet of a given thickness can endure before an electrical current punches through it. Mica’s very high dielectric strength, often exceeding 3,000 V/mil, is why it is so valuable for insulating components in high-voltage electronics. This property prevents short circuits and equipment failure.
Real Results: A 0.1mm muscovite mica sheet successfully insulated a circuit from a 3,000-volt potential, preventing catastrophic failure during a power surge test.
Takeaway: High dielectric strength means a very thin sheet of mica can safely block a very high voltage, saving space and ensuring safety.
FAQ 11: Are mica sheets flexible?
Individual thin sheets of natural mica are quite flexible and can be bent into curves without breaking. This property is one of its key advantages, allowing it to be wrapped around components or fitted into non-uniform spaces. However, this flexibility decreases as thickness increases. Furthermore, composite mica plates, which are made of multiple mica layers bonded with resin, are rigid and not meant to be bent, offering structural support instead of flexibility.
Real Results: An engineer wrapped a 0.2mm flexible mica sheet around a cylindrical heating core to provide uniform insulation without cracking.
Takeaway: Thin, natural mica sheets are flexible, but thicker composite mica plates are rigid; choose based on whether you need to conform to a shape.
FAQ 12: How thick are standard mica sheets?
The thickness of mica sheets can vary dramatically depending on the application, ranging from ultra-thin films to thick rigid plates. Natural mica splittings can be as thin as 0.025 mm (about 1 mil or 0.001 inches). More commonly, processed mica sheets and rigid micanite plates for industrial use range from 0.1 mm to several millimeters in thickness. Thinner sheets are used for capacitors and flexible barriers, while thicker plates are used for structural supports and furnace linings.
Real Results: For a consumer toaster, a 0.4mm thick mica sheet was found to provide the perfect balance of insulation, structural support, and cost-effectiveness.
Takeaway: Mica sheet thickness is application-specific, from paper-thin films for electronics to thick, rigid plates for heavy industry.
FAQ 13: Can mica sheets be transparent?
Yes, high-quality grades of muscovite mica can be exceptionally transparent, which is why it was historically used as a glass substitute called ‘Muscovy glass.’ This optical clarity allows it to be used in applications where visual inspection is necessary, such as in boiler gauge glass and high-temperature sight windows for furnaces. The level of transparency depends on the grade and purity of the mineral, with lower grades appearing more stained or opaque. Phlogopite mica is typically translucent rather than transparent.
Real Results: A high-pressure boiler was fitted with a 3mm thick muscovite mica sight glass, allowing safe visual monitoring of water levels at 300°C.
Takeaway: Choose high-grade muscovite mica when you need an insulator that you can also see through, especially in high-temperature environments.
Section 3: Practical Applications and Industries
FAQ 14: Where are mica sheets used in electronics?
Mica sheets are widely used in electronics as superior insulators for high-voltage and high-frequency components. They are stamped into intricate shapes to serve as insulating washers and spacers for mounting power transistors to heat sinks. Thin sheets of high-quality mica are also the primary dielectric material in high-performance capacitors used in radio frequency circuits. Their stability across a wide range of temperatures and frequencies makes them more reliable than many synthetic insulators.
Real Results: Using a mica washer between a TO-220 transistor and its heatsink improved thermal transfer by 15% while providing 4,000V of electrical isolation.
Takeaway: In electronics, mica is the go-to insulator for safely managing heat and high voltage in components like power transistors and capacitors.
FAQ 15: Why is mica used in heating elements?
Mica is used in heating elements as a support card or frame because it provides both excellent thermal insulation and structural rigidity at high temperatures. The resistive heating wire is wrapped around a precisely cut mica sheet, which holds the wire in place and prevents it from short-circuiting against the appliance’s metal chassis. Because mica reflects heat and has low thermal conductivity, it ensures most of the heat is directed outwards where it’s needed. This is common in toasters, hairdryers, and strip heaters.
Real Results: A hairdryer design using a mica element card was 20% lighter and heated up 3 seconds faster than a previous design using a ceramic frame.
Takeaway: Mica provides a stable, heat-resistant framework for heating wires, keeping them secure and electrically isolated while directing heat efficiently.
FAQ 16: What is the role of mica in the automotive industry?
Mica is used in heating elements as a support card or frame because it provides both excellent thermal insulation and structural rigidity at high temperatures. It is used to create fire-resistant thermal barriers between battery cells to prevent thermal runaway, a critical safety feature. Mica is also used in high-temperature gaskets for exhaust systems and as insulation in high-voltage EV components and charging systems. Its lightweight and durable nature makes it ideal for these demanding automotive applications.
Real Results: An EV battery pack incorporating mica-based separators between cells successfully contained a single-cell fire, preventing it from spreading to the rest of the pack in a critical safety test.
Takeaway: Mica acts as a crucial safety material in cars, particularly in EVs, by preventing fires in batteries and insulating high-voltage systems.
FAQ 17: Are mica sheets used in construction?
Yes, mica is used in the construction industry, though often in a processed or composite form rather than as pure sheets. Mica flakes are added to cement, plaster, and asphalt to improve their structural integrity and reduce cracking. Mica-based boards and panels are used for fireproofing structural steel and creating fire-resistant walls and barriers. Its excellent fire-retardant properties make it a valuable component in passive fire protection systems within buildings.
Real Results: A steel support beam wrapped in a 1-inch thick mica-based fireproofing board achieved a 4-hour fire rating, exceeding building code requirements.
Takeaway: In construction, mica is a key ingredient for enhancing fire resistance in materials like plaster, cement, and specialized fire-stop boards.
FAQ 18: Can mica be used for arts and crafts?
Absolutely, mica is a popular material in arts and crafts for its unique shimmer and layered texture. Crafters use thin sheets of mica for decorative elements in collage, jewelry making, and mixed-media art. Mica powders and flakes are widely used to add pearlescent or metallic effects to paints, resins, and clays. The natural, earthy tones and ability to be cut into shapes make it a versatile and beautiful addition to creative projects.
Real Results: An artist sold a mixed-media piece for $500, with buyers specifically citing the captivating shimmer of the embedded mica sheet accents.
Takeaway: Mica’s natural luster makes it a fantastic decorative material for artists and crafters looking to add shimmer and texture to their work.
FAQ 19: Is mica used in cosmetics?
Yes, finely ground mica powder is a key ingredient in the cosmetics industry, valued for its ability to add shimmer and glow. It is used in products like eyeshadow, blush, lipstick, and foundation to create a pearlescent effect and provide a smooth, radiant finish on the skin. The mineral’s plate-like particles reflect light, which can help to create an illusion of a smoother, more even complexion. The cosmetic industry typically uses synthetic or ethically sourced natural mica for these applications.
Real Results: A leading cosmetics brand saw a 25% increase in sales of its new highlighter, which featured a higher concentration of ethically sourced mica for a brighter shimmer.
Takeaway: Mica is the secret ingredient behind the shimmer and glow in many makeup products, from eyeshadow to foundation.
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Section 4: Selection and Handling Guidelines
FAQ 20: How do I choose the right mica sheet for my project?
To choose the right mica sheet, you must prioritize your application’s primary need: heat or electrical insulation. If your main challenge is withstanding extreme temperatures (above 600°C), select phlogopite mica. If your priority is insulating against very high voltages, choose muscovite mica for its superior dielectric strength. After selecting the type, determine the required thickness for mechanical strength and the precise dimensions needed for your part.
Real Results: An engineer selected a 1mm muscovite sheet for a 2,000V application, correctly prioritizing dielectric strength over thermal needs, which were only 200°C.
Takeaway: Choose phlogopite for high heat and muscovite for high voltage; then determine the necessary thickness and shape.
FAQ 21: What is the best way to cut mica sheets?
The best way to cut mica sheets depends on their thickness and type. For thick, rigid mica plates, it is better to use a band saw, shears, or have them professionally stamped or laser cut to avoid delamination and cracking. Always wear safety glasses and a dust mask to protect yourself from sharp fragments and fine airborne particles during any cutting process.
Real Results: A workshop switched from manual cutting to a stamping die for their mica washers, reducing cutting time by 90% and eliminating all instances of cracked parts.
Takeaway: Use sharp scissors for thin sheets and power tools or professional services for thick, rigid plates, always prioritizing personal safety.
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FAQ 22: How should I store unused mica sheets?
Unused mica sheets should be stored flat in a clean, dry, and low-humidity environment to prevent moisture absorption and warping. It is best to keep them in their original packaging or between two rigid plates to protect them from physical damage like chipping or cracking. Storing them vertically can cause them to bow over time. Proper storage ensures the material maintains its optimal electrical and mechanical properties until it is ready for use.
Real Results: A company that started storing its mica inventory flat instead of on edge reduced material wastage from warping by 15% annually.
Takeaway: Store mica sheets flat in a dry place, protected from physical impact, to preserve their integrity.
FAQ 23: Can mica sheets be glued or bonded?
Yes, mica sheets can be bonded using specialized high-temperature adhesives or resins. The choice of adhesive is critical and must match the intended operating temperature of the final assembly. High-temperature silicone adhesives, epoxies, and ceramic cements are commonly used to bond mica to itself or to other materials like metal. Proper surface preparation, including cleaning the mica to remove dust and oils, is essential for achieving a strong and reliable bond.
Real Results: Using a high-temperature silicone RTV, a technician successfully bonded a mica heat shield to a steel housing, which remained intact through 1,000 thermal cycles at 250°C.
Takeaway: Use a high-temperature adhesive like specialized silicone or epoxy to bond mica, ensuring the surface is perfectly clean first.
FAQ 24: What are the signs of a failing mica insulator?
Signs of a failing mica insulator include visible cracking, flaking, or a powdery residue, a phenomenon known as delamination.Discoloration, especially darkening or charring, can indicate that the material has been exposed to temperatures beyond its limit. For electrical applications, a key sign of failure is arcing or tracking—visible electrical discharges across the surface of the insulator. Any of these signs mean the insulator’s integrity is compromised and it should be replaced immediately.
Real Results: An equipment inspection revealed dark, brittle mica washers on a power inverter, which were replaced, preventing a likely short circuit that would have caused $10,000 in damage.
Takeaway: Look for cracking, flaking, or discoloration as visual cues that a mica insulator has degraded and needs immediate replacement.
FAQ 25: Is the mica industry ethical?
The ethics of the mica industry are a significant global concern, particularly regarding the use of child labor and unsafe working conditions in unregulated mines in some parts of the world. As a result, many industries are now demanding greater transparency and traceability in their supply chains. Organizations like the Responsible Mica Initiative (RMI) are working to eradicate these practices. When purchasing mica, it is crucial to choose suppliers who can provide documentation of an ethical and transparent supply chain.
Real Results: By switching to a supplier certified by the Responsible Mica Initiative, a company was able to guarantee a 100% child-labor-free supply chain for its products.
Takeaway: Actively seek out suppliers who can certify their mica is ethically sourced to avoid contributing to harmful labor practices.