Pyrolytic graphite - pyrolytic boron nitride composite element pg pbn composite

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Ceramisis Ltd

29, Harley Street,

London,

W1G 9QR,

England

Tel:44(0)20 7927 6710

Fax:44(0)20 7637 0419

sales@ceramisis.com

In vacuum substrate heating • Vacuum & high temperature materials • Vacuum furnace insulation

> Pyrolytic Graphite / Pyrolytic Boron Nitride Composite Ceramic Elements.

Pyrolytic graphite / pyrolytic boron nitride composite elements are made by chemical vapour deposition. A conducting layer of pyrolytic graphite is deposited onto a ceramic pyrolytic boron nitride substrate. A heater track is machined into the pyrolytic graphite layer, and then a protective insulating layer of ceramic pyrolytic boron nitride is deposited over the pyrolytic graphite layer to seal it. Two electrical contact points on the pyrolytic graphite layer are left exposed to enable power to be applied to the pyrolytic graphite heater track. Power densities of up to 50w/cm² can be applied to PG/PBN elements.

3" PG/PBN element with legs

These pyrolytic boron nitride / pyrolytic graphite composite elements have very low mass (<1mm thick), fast response time, with excellent chemical resistance and very high uniformity, due to its layered pyrolytic structure. They are also self supporting making for simple mounting in the vacuum chamber, ideally being mounted directly onto graphite power legs. Their operating temperature is <900°C in Oxygen, >1500°C in vacuum or inert atmosphere (with N2 present). They are ideal for UHV environments and perfect for heating small samples < Ø1" which can be placed directly onto the element. Flat elements can be made up to Ø4" x 1.5mm and cylindrical elements can also be manufactured. These PG/PBN elements are not greatly effected by deposition product. The down side of PG/PBN elements is that they can be very unreliable and prone to delamination and therefore potentially have a short life span especially at very high temperatures.

Heater Controllers and Heater Power Supply

Our range of heater controllers and power supplies offer the complete solution to powering and controlling every possible kind of heating element. All our controllers are fitted with a Eurotherm 2216e PID temperature controller which enables the heater to be held at exactly the set temperature. A tuning facility enables the controller to accurately tune to the heaters requirements and therefore avoid overshooting during temperature ramping. The control enables ramping and cooling between two set points at a specified ramp rate. The heater controller can also be controlled remotely and integrated in system computer control programs via modbus RS232, RS485 and other protocols.

All our heater controllers have power on / off switch to the whole unit, and an output enable switch to isolate the output from the controller. A 24v interlock circuit is also included to enable the power supply to be integrated with interlocks into other systems, or safety interlocks to be attached directly to the unit; which will switch off the output from the unit if the circuit is broken. This enables safety interlocks via make / break switches for things such as chamber lids closed, vacuum interlocks, cooling water flow, over temperature sensors etc.

Our standard units are 50v or 115v burst-fire output (240v x 13 amp 50hz input). The 1kw unit is available in 3U x full 19" wide rack mount, or 3U half rack mount both with integrated transformer. Our 1.5kw unit is available in 3U half rack mount only.

Above 1.5kw a separate transformer box is required. These units can be supplied with burst-fire thyristor or phase angle control thyristor which is more suitable for graphite elements.

Tel: +44 (0)20 7927 6710 • Fax: +44 (0)20 7637 0419 • sales@ceramisis.com • © Ceramisis Ltd, 29, Harley Street, London, W1G 9QR