Carbolite HTK GR Graphite Furnace

The Carbolite Graphite Furnace HTK GR operates with rough/fine vacuum, protective gases such as Nitrogen/Argon, and reactive gases like Hydrogen and Carbon Monoxide. The Graphite Furnace HTK GR cannot operate in an Oxygen atmosphere due to the Graphite insulation.

The rectangular design with a front door allows for easy loading and unloading. The HTK GR range is available in up to six different sizes. The smallest designs with a capacity of 8 litres and 25 litres are typically employed by laboratories for research and development. The 80 litre, 220 litre, 400 litre or 600 litre furnaces are predominantly used as pilot manufacturing systems or large scale production. 

The HTK GR is based on Graphite insulation material, as well as graphite heating elements. With maximum temperatures up to 2200 °C, the HTK GR is suited for extreme heat treatment needs. Upon request, the system can be equipped with a Graphite retort that is capable of a defined gas guiding flow within the unit and improves temperature uniformity to < ± 10 °C. For processes with strong outgassing, the retort protects the heating elements and increases the lifetime of the furnace.

Application Examples

graphiting, pyrolysis, siliconization, sintering, technical ceramics

Inside the chamber, heating elements are positioned at the bottom, left, right, and top sides of the furnace chamber allowing for improved temperature uniformity. For larger volumes, the back wall and front are equipped with heating elements to maintain excellent temperature uniformity. The HTK W, HTK MO, HTK GR and HTK KE furnaces are surrounded by a water cooled vessel; thus classifying, the HTK systems as a cold wall furnace. The cooling water is guided through the double walled vessel.

Upon request, the HTK GR can be operated up to 3000 °C. For operation at 3000 °C, the furnace is specially designed with a specific isolation thickness, optimal positioning of the heating elements, and a pyrometer for temperature measurement and control. The pyrometer directly measures the heat radiation by optical methods via a window inside the furnace and is not directly inserted into the furnace.

This measurement principle only works if a sufficient amount of radiation is emitted. The needed radiation is only generated at temperatures exceeding 400 °C. For lower temperatures, a sliding thermocouple is used to control the lower temperatures.

Because of the increasing vapor pressure of graphite, 3000 °C operation is only possible under inert gas atmosphere. Additionally, the high vapor pressure also results in carbon being released to the atmosphere. For carbon sensitive samples, a metallic furnace high temperature furnace must be used.