The tube furnace was first created in the early 20th century to manufacture pre-lightbulb ceramic filaments, used in glowers and Nernst lamps. Today, such furnaces are employed where precise temperatures are required, usually in a lab or manufacturing setting. Solid state chemists in find this device indispensable. It’s also used in manufacture. Coating, hardening, drying, aging samples, purification, brazing, annealing, and sintering sublimation are among it’s uses. So how does it work?
Samples are placed into its heated tube for certain purposes. Tube furnaces can have a horizontal or vertical orientation. Vertical tubes take up less space and provide faster heating. Samples are usually placed in a ceramic or metal boat, then shoved inside with a push rod. Any gases formed during the process pass through the tube and out a bubbler.
Desirable options include rapid thermal processing which allows for maximum heating and cooling, a gas processing capability, a rotating tube for coating uniformity and superior powder processing, and multi-zone heating--which allows for independent control of multiple temperature zones. Tube furnaces have a variety of uses including synthesizing or purifying inorganic compounds, drying, brazing, melting, material testing, gas processing, and much more.