Top hat furnace - HBO

The metallic hood furnaces (HBO) generate the lowest achievable operation pressures. The highest purity gas atmosphere is attained due to the vacuum capability.

The materials used in the construction are selected for the lowest vapour pressures at the highest temperatures. Heat treatment up to the highest temperatures can be achieved without harming the heating elements or insulation material. Radiation shields are used to provide thermal insulation, which are made from the same material as the heating elements, and no fibrous thermal insulation is used.

Two varieties of HBO furnaces are produced: those made using molybdenum heating elements and radiation shields are suitable for use up to 1600 °C; those made using tungsten heating elements and radiation shields are suitable for use up to 2200 °C.

Nitrogen, Argon, and Hydrogen gases are available for use in mixed or pure forms. Additional gases can be installed upon request. A slight overpressure or controlled partial pressure between 10 and 1000 mbar can be achieved. Partial pressure provides a defined gas flow through the furnace.

Due to the complete metallic design, the final vacuum level in the HBO can reach the high vacuum range and better than 5 x 10^-6 mbar. Depending on the vacuum requirements, the vacuum is provided by different pumping stations. Ultrahigh vacuum options are available upon request. Gases are controlled by various dosing and controlling devices. The temperature in each of the three heating zones is individually controlled to maintain the best uniformity.

Standard features

• Precisely defined atmosphere with highest possible purity (6 N or better)
• Best possible vacuum
• Fast heat up and cool down upon request
• Hydrogen partial pressure operation upon request
• Precisely controlled vacuum pumping speeds appropriate for powders
• Certified safety management for flammable and toxic gases
• Fully automatic operation
• Data recording for quality management

Options (specify these at time of order)

• Vacuum system for pre-vacuum, fine vacuum or high vacuum operation
• Software for automated operation, data tracking and data export
• Reaction gas equipment for more than one inert gas, retorts, afterburners
• Water cooling system

View inside of the HBO Hood Furnace

1. gas inlet or outlet
2. gas outlet or inlet
3. pumping unit attached from below
4. location of the thermocouple
5. radiation shields
6. heating elements
7. water cooled vessel
8. sample holder (built on request)

The HBO Hood Furnace is constructed of metallic materials only with a total of 9 radiation shields. It has three heating zones to improve the temperature uniformity over the whole length and also to enable preheating of the incoming gas if required. The three heating zones consist of the mantle, top and bottom heater. The mantle heater is designed for the highest mechanical stability. An optional metallic retort can be specified to protect the heating elements should any outgassing of the sample occur and improve the temperature uniformity.

To insulate the heat in metallic furnaces, tungsten or molybdenum radiation shields are used. The HBO has a double walled, water cooled vessel. The sample holder is positioned as required.

Each of the three heating zones are individually controlled and protected by an additional over-temperature protection thermocouple; therefore, unattended operation is possible. An optional fast cooling system significantly reduces the cool down time.