ELECTRONIC SPACE PRODUCTS INTERNATIONAL

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E-Mail: sales@espimetals.com

PYROLYTIC GRAPHITE

              Pyrolytic graphite is a unique form of graphite manufactured by decomposition of a hydrocarbon gas at very high temperature in a vacuum furnace. The result is an ultra-pure product which is near theoretical density and extremely anisotropic. This anisotropy results from the layered structure. As an example, pyrolytic graphite exhibits thermal conductivity consistent with the best conductors in the horizontal plane and lower than alumina brick in the vertical plane. Mechanical, thermal, and electrical properties are generally far superior to conventional graphites. Pyrolytic graphite is available as plate, free-standing shapes (crucibles, boats, tubes, etc.) and as an impermeable coating on graphite and other substrates. Some other features of pyrolytic graphite include:

                                           ∙            Chemically Inert

                                           ∙            High Purity

                                           ∙            Stable to 3000 ^oC

                                           ∙            Impermeable

                                           ∙            Directional Electrical & Thermal Characteristics

                                           ∙            Self-Lubricating

                                           ∙            Nondusting

                                           ∙            Low Etch Rate

Typical Physical Properties (Room Temperature):

Density: 2.18 - 2.22 g/cc

Flexural Strength (horizontal plane): 18,000 psi (120 MPa)

Tensile Strength (horizontal plane): 12,000 psi (80 MPa)

Compressive Strength (horizontal plane): 15,000 psi (100 MPa)

Young’s Modulus (horizontal plane): 3 x 10⁶ psi (20,000 MPa)

Crystal Structure: Hexagonal

  (C/2 Spacing): (3.42 Å)

Melting Point (Atmosphere): Sublimes at 3650 ^oC

Outgassing: Negligible

Coefficient:

  Thermal Expansion (horizontal plane): 0.5 x 10⁶ cm/cm/^oC

  Thermal Expansion(vertical plane): 6.5 x 10⁶ cm/cm/^oC

  Thermal Conductivity (horizontal plane): 400 Watts/Meter ^oC

  Thermal Conductivity (vertical plane): 3.5 Watts/Meter ^oC

  Electrical Resistance (horizontal plane): 0.5 10^-3 ohm-cm

  Electrical Resistance (vertical plane): 0.5 ohm-cm

Purity:

  Total Impurities: .01% Maximum

  Total Metallic: 10 ppm