A Unique Combination

PBN/PG resistance heating elements combine the unique electrical, chemical, and thermal properties of PBN, a dielectric material, and Pyrolytic Graphite (PG), an electrical conductor, to produce a truly advanced heating system.

These non-brittle refractory materials owe their exceptional purity to the high temperature, chemical vapor deposition (CVD) production method.  The high thermal conductivity and anisotropy of both materials result in excellent thermal uniformity.

Performance Advantages

PBN/PG "printed circuit" heaters utilize PBN as an insulating substrate and Pyrolytic Graphite as the resistive element. In non-oxidizing environments, this combination of unique materials delivers performance advantages not available in conventional thermal systems.

• Operating temperatures to 1500°C and higher.
• Superior performance in ultra high vacuum.
• Chemically inert to most corrosive gases, liquids.
• Unaffected by most molten metals.
• Long life, dimensionally and electrically stable.
• High resistance for low cost power supplies.
• Mechanically durable, thermally shock resistant.
• Unaffected by vibration.
• Tailored thermal gradients for specific requirements.
• Ultra-fast response, low thermal mass.
• Power outputs to 35 watts/cm2 (325 watts/in2) and higher.
• Dielectric, fully dense, ceramic surface.
• Often suitable for slightly oxidizing atmospheres.

Design Versatility Momentive manufactures heaters as flat plates, with surface electrical connections inside the heated area or located outside the heated area on tabs.  Heaters can also be made as 3-D elements on chemical vapor deposited (CVD) PBN crucibles and tubes. PBN/PG Heaters have been made as small as 5 mm diameter, and as large as 300 mm.

Location of the contact tabs provides design flexibility for enhanced thermal uniformity.  Resistance patterns can be circular or diagonal, and can have varying web width to tailor local flux.  Multiple, independent zones can be incorporated for flexible thermal management. PBN/PG Heaters are made on either PBN plate and shape substrates, with an overall wall thickness of about 2 mm; or on a sealed graphite core substrate for the ultimate in robust, uniform design, with a thickness of 5-8 mm.

Standard Designs

The majority of PBN/PG Heaters are made-to-order, but Momentive Performance Materials offers three standard sizes that have proven useful for many customers.  These standard heaters are made on PBN plate substrates with surface electrical contacts. The typical pattern is shown below.

PBN Plate Substrate HTR1001 HTR1002 HTR1003

Typical Dimensions [mm] and Operating Characteristics