Grafoil®, or Flexible graphite, is a soft sheet form of compressed natural graphite made from exfoliated mineral flake(crystalline) graphite. Due to its flexible texture, it is commonly called flexible graphite. Flexible graphite is a generic commercial term. Many people call it grafoil®, which is a brand name that is owned by GrafTech. Grafoil® was first introduced by Union Carbide in the 1960s. Flexible graphite may also be referred to as graphite foil, graphite sheet, graphite paper, or simply graphite. Other main flexible graphite brand names include: MinGraph®, Sigraflex®, Flexicarb®.
Flexible graphite comprises 95% – 99% carbon contents. It inherits many characteristics of natural mineral graphite. Flexible graphite is considered as a non-metallic material, but it is thermally and electrically conductive like metal. Formed with the same element carbon as diamond, flexible graphite is the softest material with a score 1 of 10 on Mohs hardness scale. Flexible graphite is inert to most chemicals, resistant to heat up to several thousand degrees. All these characteristics contribute to the mineral graphite atomic structure. In the structure, the hexagonal bond is strong, but the bond between layers is weak. By breaking the bond between layers, the mineral graphite can be exfoliated several hundred times bigger. Essentially flexible graphite is made of compressed exfoliated mineral graphite.
Flexible graphite is being used in a wide range of industrial applications:
- Gasket and Seal Flexible graphite is an excellent sealing and gasket material and can be used for making chemical resistant and high-temperature resistant gaskets, seal parts, compression packing, etc.
- Lubrication Flexible graphite is a solid lubricant and can also be used in various metal fabrication processes or other mechanical process.
- Heat Managerment Using its directional heat conductivity characteristics, flexible graphite can be used as liners in industrial furnaces, as well as in electronic devices to control and spread heat flow.
- Flexible graphite can also be used in many other applications including EMI (electromagnetic interference) shielding and gasketing, stress sensing, vibration damping, spark plasma sintering(SPS), and other thermal, electronic or electrochemical applications. Flexible graphite is also being used in the newest development of graphene manufacturing.