Phlogopite Mica (Heat Resistant, d50 100µm)

Phlogopite mica is a magnesium-rich phyllosilicate mineral (KMg₃(AlSi₃)O₁₀(OH)₂) that offers superior thermal stability compared to muscovite mica, with a service temperature up to 1000°C. The golden-brown colored platelets have aspect ratios typically exceeding 25:1, providing excellent barrier, reinforcing, and thermal insulation properties in demanding high-temperature composite applications.

Phlogopite's thermal stability arises from the magnesium-iron substitution in its octahedral layer, which is more resistant to dehydroxylation than the aluminum-dominant muscovite structure. This makes phlogopite the preferred mica variety for high-temperature electrical insulation (class H and C insulation systems), fireproof composites, and refractory applications where muscovite would undergo structural degradation.

In the composites industry, phlogopite mica is used in high-temperature resistant epoxy and phenolic composites for aerospace and automotive thermal management applications. Its combination of electrical insulation (dielectric strength >500 V/mil) and thermal conductivity (1–3 W/m·K through the platelets) makes it valuable in thermal interface materials. Phlogopite mica paper and tape are used as class H winding insulation in motors and transformers. It is also a key ingredient in fire-resistant composite building panels certified to fire resistance standards.