Ceramisis also supply Ceramic and graphite components produced by Chemical Vapour Deposition (CVD), such as Solid Pyrolytic graphite (PG) and solid Pyrolytic Boron Nitride (PBN), and can also produce composite products made from these to materials combined, such as heater elements. We produce components such as boats, crucibles and heaters, which are also well very suited to Ultra High Vacuum (UHV) applications due to their very high purity, low outgassing and high operating temperatures.

With machinable ceramics, such as Macor, Shapal, Boron Nitride, Boron Nitride Silica mix (BNS26), Machinable 96% Alumina, and high density graphite, components are produced using conventional machining techniques from stock bar, rod and plate. No post firing is required after the components are machined.
CVD materials such as Pyrolytic Graphite (PG) and Pyrolytic Boron Nitride (PBN) components are produced at very high temperatures by depositing material onto a substrate or mandrel. Post machining is possible although the deposited thickness of the material is normally only a few millimetres.
Ceramisis also supply a complete range of high temperature asbestos free ceramic textiles, in cloth, rope, sleeve, blanket and yarn form. We can offer the well known Dalfratex range of ceramic textiles.

Macor - is a machinable glass ceramic and easily machined with conventional metal working tools. It is an ideal prototyping material for use in a vacuum environment at low or high temperature. Continuous use temperature is 800 C with short exposure up to 1000C, and the coefficient of thermal expansion matches most metals. Macor has zero porosity, a very low thermal conductivity and good electrical insulation properties, and so is ideal for in vacuum heater isolators and supports. It does however have poor resistance to thermal shock.

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Shapal - is machined with diamond tooling and has high mechanical strength and high thermal conductivity. It has very good resistance to thermal shock and is based on the worlds first translucent aluminium nitride ceramic. Shapal ceramic unique characteristics make it suitable for a wide range of applications in the vacuum and nuclear industries. It has zero porosity, low our gassing rates, is not affected by most etch plasmas or ionizing radiation and easily joins to its self or other materials. Its maximum operating temperature is 1900C.

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Boron Nitride - Boron nitride is a unique material. it offers outstanding thermal conductivity, excellent dielectric strength, very good thermal shock resistance, is self lubricating and is easily Machinable. This material is an advanced synthetic ceramic available in powder, solid, liquid and aerosol spray forms. In an oxidizing atmosphere it can be used up to 900°C. However, in an inert atmosphere some grades can be used as high as 3000°C. Grades are available with a very low porosity and ultra high strength for use in semiconductor processing and mechanical applications. Great care must be taken when using boron nitride components over 1000C in high vacuum. Some grades contain calcium carbonate binders that will liquefy around 1000C in high vacuum causing great damage to the vacuum chamber and pumping system. We have a binder free 100% boron nitride grade that we recommend for use above 1000C in high vacuum. Boron Nitride is Hygroscopic and will absorb moisture if left exposed to the atmosphere. This moisture must be baked out at low temperature before operating at high temperature.

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Boron Nitride Silica Mix (BNS26) - BNS26 is a unique material combining Boron Nitride with Silica, essentially giving some of the best properties of both Macor and Boron Nitride. BNS26 is a hydrophobic advanced ceramic and is resistant to moisture (unlike boron nitride). It is suitable for the most severe electrical applications, is an excellent refractory material up to 1400C, and has excellent resistance to thermal shock. It is an ideal material for heater element supports and bases.

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Alumina (96% Machinable) - useable continually to 1650°C with a melting point of 1870°C, 96% Alumina machinable ceramic is manufactured from high purity alumina by a unique process. Unlike standard alumina this unique manufacturing process enables our 96% Alumina to be machined with conventional tooling on standard machine shop equipment. No post heat treating after machining is required offering the convenience and economy of an in house capability for alumina parts. The chemical, thermal and electrical properties of our 96% Alumina machinable ceramic are equivalent to standard high alumina ceramics, with good resistance to thermal shock. Our Alumina 96% machinable ceramic is available in various standard rod sizes up to Ø3.5" x 12" long, and plates up to 6" x 6" x ¾".

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Quartz - We supply quartz rods and tubes for use as element supports. Partial machining is possible to put holes and slots into the quartz rods and tubes, making them ideal for use as tungsten element supports (bespoke tungsten elements are also produced by Ceramisis). Quartz is ideal for use in UHV and has very low thermal conductivity it is also transparent to infra red, and so is slow to heat, making it an ideal material for element supports and covers.

High Density Graphite - High density graphite and carbon carbon composite are ideal materials for in vacuum heating elements. Chemically the same, high density graphite and carbon carbon composite materials are very inert, get stronger with temperature, has low expansion coefficient and will not seize after heating. High density graphite is brittle but inexpensive and machined conventionally from large blocks, therefore very large sized graphite elements can be produced in a variety of shapes and sizes. Our high strength ultra fine grained graphite enables small very intricate elements to be manufactured also. Graphite has a low expansion coefficient and is not degraded by constant heating and cooling, and also gets stronger as its temperature increases. Its low resistivity means it requires high current power supplies and therefore large feedthroughs and cables which can be expensive. It can operate over 2000 °C in an inert atmosphere or in vacuum and <500°C if oxygen is present. Graphite elements have the ability to take very high current density, and therefore very fast ramp up times can be achieved. Its relatively high specific heat capacity means that cool down times in vacuum can be quite long. Apart from reacting with oxygen from 500C, graphite is otherwise very inert and can therefore operate in very corrosive or aggressive atmospheres without degradation. Particle contamination and open porosity can be a problem with graphite, but this can be overcome with coatings, or impregnations detailed below. Graphite elements are suitable for UHV applications, but must undergo initial out-gassing process due to its open porosity.

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