Graphite purification

• Purification of graphite, CFC, and carbon felt
  • Vaporizing carbide-bound impurities through chlorine (Cl) or fluorine (F) carrier.
• Re-purification of processed parts removing depositions or process caused impurities (e.g. out of MOCVD process)
• Recycling of hot zone parts from Cz-pullers (outbaking)

• Some impurities (e.g. sulphur) can be vaporized using only vacuum and high temperature.
• Other impurities cannot be vaporized, because they form very stable carbides 
• Therefore, chlorine and fluorine is needed to form chemical components which can be vaporized.
• The volatile components are carried from the hot zone to a cold trap and filter.
• A scrubber removes non-reacted halogens from the exhaust gas. 

• Process gas exhausted from the purification process may be corrosive and/or harmful. 
  • harmful components must be extracted from the gas in an abatement system (scrubber).
• The operating liquid is caustic soda lye, caustic potash lye or similar.
  • The pH value is controlled automatically.
• Process gas passes the sprayed caustic in counterflow to achieve the largest possible contact surfaces and dwell times.

Our graphite purification furnaces are specifically designed for the puriication of graphite and CFC components. Contaminants are removed at high temperatures under vacuum conditions. Treatment with reactive or non-reactive gases is performed according to customer requirements. Our customers report impressive purity levels of better than 3 ppm. PVA TePla systems are renowned for delivering maximum system uptime.

An initial purification of the batch is performed at high temperatures under vacuum, where volatile components are thermally removed. Further treatment uses halogen-containing gases, allowing chlorine and fluorine to act as effective reaction partners in the process. The maximum process temperature reaches 2,200 - 2,400°C.

These extreme process conditions demand the highest safety standards and a precise understanding of the properties of the materials used. The selection of materials and components is made with consideration for the reactive atmosphere, ensuring maximum system uptimes.

The process gases and their reaction products require post-treatment of exhaust gases to comply with TA Luft regulations or comparable standards. This post-treatment is generally performed using a gas scrubber. Batch handling systems tailored specifically to the equipment complete the comprehensive solution package.

For the production of standard and customer‑specific pressure vessels, components, and vacuum chambers, we operate our own manufacturing facility in Europe. It is entirely powered without the use of fossil fuels, fully aligning with our sustainability objectives.

Key advantages at a glance

• Fast delivery times: Greater independence from external suppliers.
• Flexible customization: Short‑notice design changes can be implemented immediately.
• Reliable material availability: Constant access to high‑quality materials thanks to long‑standing local partnerships.
• Highest processing quality incl. standards: Performing welding operations in‑house allows direct monitoring of joint conformity, which is essential for meeting standards such as UNI EN ISO 3834.
• Top‑tier standards: Naturally, our facility meets our stringent requirements for quality, safety, and sustainability.