A tube furnace is an electronic heating device that exposes materials to different temperatures with precise control and uniformity. It houses a working tube or vessel that processes or heats small samples in an inert atmosphere. This lets you expose materials to a wide range of temperatures in varying periods.
Its refractory heating coils or ribbons are embedded in the ceramic heating chamber and are responsible for the uniform temperature distribution. A tube furnace has various applications, including heat treatment, crystal growth, synthesis, and purification of compounds.
Types of Tube Furnaces
1. Split Tube Furnace
The split tube furnace enables you to access the internal chamber easily with its hinged body that opens halfway. This is especially helpful when installing or removing work tubes and vessels with ends and fittings that may not fit with other types of tube furnaces. It’s often used in academic and R&D applications such as tensile testing, pyrolysis, chemical vapor deposition, and graphitization.
A split tube furnace with a quartz tube has several benefits. Not only is it more durable than others, but it also has a high-temperature resistance with a melting point of 108 °C. This ensures a stable thermal performance even when temperatures suddenly change. Additionally, the quartz material has a higher corrosion resistance than ceramics and stainless steel, with a good insulation feature for electricity.
2. Solid Tube Furnace
This lab tube furnace doesn’t open vertically or lengthwise, unlike the split tube. However, this type can handle applications continuously using a specific sample size in its single or multi-heating zones. This provides temperatures with consistency and precision throughout the heating process, with its built-in diffusers protecting against heat radiation.
It usually comes with a central hot zone where process tubes pass through, with end or top plugs protruding from the body to access the processing chamber easily. Metallic sheath elements are also present in areas where increasing heat is needed. With the lightweight ceramic and fiber insulation, the materials you’re testing can quickly heat up, recover, and cool down.
3. Rotary Tube
A rotary tube furnace is a metal drum lined with refractory material and mounted at an angle. Most labs use this furnace for physiochemical processing of loose material as it heats and mixes samples simultaneously within a controlled atmosphere.
During heat treatment, samples pass through the work tube in a circular path due to the rotating of the circular furnace. This ensures even heat distribution throughout the sample size.
Rotary tube furnaces are designed to continuously process materials by applying heat in multiple thermal control zones, from a heat source to a rotating tube holding the sample. Burning pulverized, solid, gaseous, or liquid fuel into its work tubes creates heating gasses that flow to the samples.
The classification of rotary furnaces depends on the type of heat exchange (i.e., parallel or opposing gas flow) and method of transferring energy (i.e., direct, indirect, or combined).
