Phlogopite Rigid Sheet
Phlogopite Rigid Sheet is available in grades P and PC — rigid mica laminates composed of Cogemica Phlogopite mica bonded with a resin binder, rated for continuous service at 700°C and intermittent exposure to 1000°C. The material provides a dielectric strength of 25 kV/mm at 20°C and compressive strength of up to 330 MPa (P) / 310 MPa (PC) at room temperature. Grade PC is the desmoked version of grade P, engineered to release very low fumes during first heating above 250°C.
Key Properties
- Heat Resistance (Continuous / Intermittent Service): 700°C / 1000°C
- Thermal Conductivity (Perpendicular / Parallel): 0.3 W·m⁻¹·K⁻¹ / 3 W·m⁻¹·K⁻¹
- Dielectric Strength, 20°C: 25 kV·mm⁻¹
- Compressive Strength, 20°C: P: 330 MPa / PC: 310 MPa
- Volume Resistivity, 20°C: > 10¹⁶ Ω·cm
- Fire Resistance Classification: UL 94 94V-0; BS 476 Class 1
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- Specifications
- Applications
- General Info
- FAQs
Physical Properties
| Property | Value | Test Method |
| Thickness | P: < 80 mm / PC: 1.5 – 10 mm | IEC 371-2 |
| Tolerance, 1.5 – 5.0 mm | ± 7% | IEC 371-2 |
| Tolerance, 5.0 – 30 mm | ± 5% | IEC 371-2 |
| Tolerance, 30 – 80 mm | ± 3% | IEC 371-2 |
| Mica Content | 90% | IEC 371-2 |
| Bond Content | 10% | IEC 371-2 |
| Density | 0.69 g/cm³ | IEC 371-2 |
| Untrimmed Plate Size | 1220 x 1016 mm | — |
| Usable Area | 1200 x 1000 mm | — |
Mechanical Properties
| Property | Value | Test Method |
| Compressive Strength, 20°C | P: 330 MPa / PC: 310 MPa | ISO 604 |
| Compressive Strength, 200°C | P: 240 MPa / PC: 225 MPa | ISO 604 |
| Tensile Strength | P: 110 MPa / PC: 100 MPa | ISO 527 |
| Bending Strength | P: 170 MPa / PC: 150 MPa | ISO 178 |
Thermal Properties
| Property | Value | Test Method |
| Heat Resistance, Continuous Service | 700°C | — |
| Heat Resistance, Intermittent Service | 1000°C | — |
| Resistance to Thermal Shocks, up to 6 mm thickness | 400°C | — |
| Resistance to Thermal Shocks, above 6 mm thickness | 200°C | — |
| Weight Loss, Continuous Service | < 1% | — |
| Weight Loss, Intermittent Service | < 1% | — |
| Thermal Conductivity, Perpendicular | 0.3 W·m⁻¹·K⁻¹ | — |
| Thermal Conductivity, Parallel | 3 W·m⁻¹·K⁻¹ | — |
| Specific Heat | 866 J·kg⁻¹·°C⁻¹ | — |
| Thermal Expansion, Perpendicular | 100 x 10⁻⁶ K⁻¹ | — |
| Thermal Expansion, Parallel | 10 x 10⁻⁶ K⁻¹ | — |
| Water Absorption, 24h / 23°C | < 1% | — |
Electrical Properties
| Property | Value | Test Method |
| Dielectric Strength, 20°C | 25 kV·mm⁻¹ | IEC 243-1 |
| Dielectric Strength, 400°C / 1 hour, tested at 20°C | 13 kV·mm⁻¹ | IEC 243-1 |
| Dielectric Strength, 600°C / 1 hour, tested at 20°C | 10 kV·mm⁻¹ | IEC 243-1 |
| Tracking Resistance | 525 V | IEC 112 |
| Volume Resistivity, 20°C | > 10¹⁶ Ω·cm | IEC 93 |
| Volume Resistivity, 400°C / 1 hour, tested at 20°C | > 10¹² Ω·cm | IEC 93 |
| Volume Resistivity, 600°C / 1 hour, tested at 20°C | > 10⁹ Ω·cm | IEC 93 |
| Loss Factor, 160°C | < 1% | IEC 250 |
| Relative Permittivity, 20°C | 6 | IEC 250 |
| Relative Permittivity, 400°C / 1 hour, tested at 20°C | 6.5 | IEC 250 |
| Arc Resistance | ≥ 420 sec | ASTM D495 |
| Arc Resistance Classification | L3: 2.2.1.0 | VDE 0303 |
Flame & Fire Performance
| Property | Value | Test Method |
| Fire Resistance Classification | Class 1 | BS 476 |
| Fire Resistance Classification | Class A1 | NBN 21-203 |
| Fire Resistance Classification | MO and FO | NFF 16 101 / NFF 16 102 |
| Fire Resistance Classification | 94V-0 | UL 94 |
| Fume Toxicity Index | 0.16 (very low optic density of fumes, non-toxic) | CEI 2037/85 |
Compliance
- BS 476 — Compliant (Class 1)
- NBN 21-203 — Compliant (Class A1)
- NFF 16 101 / NFF 16 102 — Compliant (MO and FO)
- UL 94 — Compliant (94V-0)
- CEI 2037/85 — Compliant (Fume toxicity index 0.16)
- Insulating spacer between plate and die in forging presses to minimize heat transfer through press mechanisms
- Guide components in hollow glassware manufacturing exposed to temperatures exceeding 700°C
- Insulation in high-voltage appliances requiring resistance to electric arc and erosion
- Sealing components for gas distribution network connections requiring pressure resistance and fire-safe sealing
- Thermal and electrical insulation in induction and arc furnace construction, including induction-heated brazing fixtures for aluminum and copper components
Common industries: metal forming and forging, glass manufacturing, high-voltage electrical equipment, gas distribution/utility, industrial furnace and induction heating equipment.
Phlogopite Rigid Sheet (grades P and PC) is a rigid mica laminate manufactured by COGEBI to IEC 371-2 from Cogemica Phlogopite mica combined with a bonding resin (90% mica content, 10% bond content). Compared to the Muscovite-based M and MC grades, the Phlogopite-based P and PC grades offer higher resistance to heat and are recommended for applications operating continuously at temperatures above 500°C. Grade PC is the desmoked version of grade P: during first application at temperatures above 250°C, fumes released from PC are very low.
The material is impervious to most chemicals, including oil and grease, and is asbestos-free, ecologically safe, and non-toxic. Water absorption after 24 hours at 23°C is less than 1%. Sheets up to 2 mm thick can be punched using tools fitted with draw rings; thicknesses above 2 mm require machining (sawing, drilling, etc.) with high-speed steel or tungsten carbide tooling, and the material has unlimited shelf life when stored in a dry place at room temperature.
Phlogopite Rigid Sheet (grades P and PC) carries a fume toxicity index of 0.16 per CEI 2037/85, reflecting very low optical density of fumes and non-toxic behavior. Compliant with BS 476 (Class 1), NBN 21-203 (Class A1), NFF 16 101 / NFF 16 102 (MO and FO), UL 94 (94V-0), and CEI 2037/85.
What differentiates Phlogopite Rigid Sheet (grades P/PC) from the Muscovite-based M/MC grades, and from each other?
Phlogopite Rigid Sheet (grades P and PC) is built from Cogemica Phlogopite mica rather than Muscovite, giving higher resistance to heat and making it the recommended choice for applications operating continuously at temperatures above 500°C (700°C continuous / 1000°C intermittent, versus 500°C / 700°C for the M/MC grades). Within the Phlogopite Rigid Sheet line, grade PC is the desmoked version of grade P: it emits very low fumes during first heating above 250°C, but is supplied only in the 1.5 – 10 mm thickness range (versus up to 80 mm for P) and has slightly lower compressive, tensile, and bending strength.
Why does heat resistance matter when selecting Phlogopite Rigid Sheet (grades P/PC) for electromechanical and thermomechanical applications?
Phlogopite Rigid Sheet (grades P/PC) is rated for continuous service at 700°C and intermittent exposure to 1000°C, allowing it to maintain electrical insulation, dimensional stability, and resistance to open flame in applications such as furnace linings, forging press insulation, and high-temperature guide components where lower-temperature-rated insulating materials would degrade or fail. The TDS notes that application parameters — pressure, clamping, temperature gradient, rate of temperature rise, and cooling — can significantly affect the maximum usable temperature.
What is the service temperature range for Phlogopite Rigid Sheet (grades P/PC)?
Continuous service is rated to 700°C, with intermittent service rated to 1000°C, per the TDS thermal properties data.
Is Phlogopite Rigid Sheet (grades P/PC) suitable for flame-rated and fire-resistant environments?
Yes. Phlogopite Rigid Sheet (grades P/PC) is classified BS 476 Class 1, NBN 21-203 Class A1, NFF 16 101/102 MO and FO, and UL 94 94V-0, and carries a fume toxicity index of 0.16 per CEI 2037/85 (very low optic density of fumes, non-toxic).
How should Phlogopite Rigid Sheet (grades P/PC) be specified?
Specify grade (P or PC), thickness, fire/fume compliance requirements, dimensional tolerances, and finished format (sheet stock, machined component, or punched part).
