Momentive
Americas
|

 Applications
 Boron Nitride Paints
 Boron Nitride Powder
 Carbide Coatings
 Graphite Monochromators
 Heaters & Heater Assemblies
 High Thermal Conductivity Graphite & Composites
 Hot Pressed Boron Nitride Composites
 Hot Pressed Boron Nitride Shapes
 Pyrolytic Boron Nitride
 Pyrolytic Graphite
 Titanium Diboride Powder
 Product Literature

 Technical Articles & Data
 Order Center
 Order a Sample
 Strongsville AS 9100 Certificate
 Global ISO 9001 Certificate

Pyrolytic Graphite (PG)

PG  

 

Pyrolytic Graphite (PG) is a unique form of graphite manufactured by decomposition of a hydrocarbon gas at very high temperature in a chemical vapor deposition furnace.  The result is an ultra-pure product which is near theoretical density and extremely anisotropic.  This anisotropy results from the layered structure as indicated in the drawing.  As an example, PG exhibits a thermal conductivity comparable with the best conductors in the "ab" plane and lower than alumina brick in the "c" direction.  Mechanical, thermal, and electrical properties are generally far superior to conventional graphites. PG is available as plate or machined shapes and as a coating on graphite and other substrates. Typical properties are listed below  

 

Pyrolytic Graphite

 

Typical Properties  

    Density 

  2.18-2.22 g/cc 

    Flexural Strength 

(a b)

  18,000 psi (120 MPa) 

    Tensile Strength 

(a b)

  12,000 psi (80  MPa) 

    Compressive Strength

(a b)

  15,000 psi (100 MPa) 

    Young’s Modulus 

(a b)

  3x106 psi (20,000 MPa) 

Coefficients 

    Thermal Expansion 

(a b)

  0.5x10-6 cm/cm/°C 

  

(c)

  2-x10-6 cm/cm/°C 

    Thermal Conductivity

(a b)

  300 watts/meter °C 

  

(c)

  3.5 watts/meter °C 

    Electrical Resistance

(a b)

  0.5x10-3 ohm-cm 

  

(c)

  0.5 ohm-cm 

    Crystal Structure 

  Hexagonal 

    (C/2 Spacing) 

  

  (3.4Å) 

    Melting Pt. (Atmosphere) 

  Sublimes @ 3650°C 

Purity 

    Total 

  0.01% Maximum 

    Total Metallic   10 ppm
    Outgassing   Negligible

 


  

PG Coatings 

PG is a popular coating for sealing machined graphite hardware which does not require oxidation protection.  It is the most anisotropic commercially available coating and is therefore useful where thermal management is important.  PG coatings can be applied to PBN crucibles and plates as in Momentive's patented "Hot-Lip" MBE crucibles and PBN/PG heaters.

  

  

Performance Features

  • Chemically Inert 
  • High Purity
  • Stable to 3000°C
  • Impermeable
  • Directional Electrical & Thermal Characteristics
  • Self-Lubricating
  • Nondusting
  • Low Etch Rate

A Unique Combination

PG, a very refractory electrical and thermal conductor, can be combined with PBN, a superb dielectric, to form heating elements for high temperature UHV applications.  These nonbrittle refractory materials owe their exceptional purity to the high temperature vapor deposition production method.  The high thermal conductivity and anisotropy of both materials result in excellent thermal leveling characteristics.

Contacts

Contacts for Americas
[Choose Region]
Momentive Performance Materials Inc
Ceramics Business 22557 W. Lunn Road Strongsville, OH 44149
North America

Customer Service

+1 440 878 5700
+1 440 878 5928 fax
cs-na.ceramics@momentive.com
EMEA

Customer Service

+49 4152 9380
+49 4152 938 136 fax
cs-eur.ceramics@momentive.com
Asia

Customer Service

+81 3 5114 3769
+81 3 5114 3777 fax
cs-asia.ceramics@momentive.com