Tube furnace air calcination is achieved by controlling air circulation to achieve high-temperature treatment of materials in an oxidizing atmosphere. Let's take a detailed look below!

1200 ℃ High Temperature Tube Furnace (Click on the image to view product details)

1. Core principle
The tube furnace generates high temperature through electric heating elements such as resistance wires, silicon carbon rods, and silicon molybdenum rods, and the furnace is insulated with refractory materials such as alumina fibers. When air is used for calcination, air flows in from one end of the furnace tube and comes into full contact with the sample, providing the oxygen required for the oxidation reaction while carrying away the gases produced by the reaction (such as CO ₂, H ₂ O). This design achieves:
Oxidative atmosphere: Oxygen in the air promotes sample oxidation (such as metal oxidation, organic matter decomposition).
Temperature uniformity: Gas flow reduces the temperature gradient inside the furnace, ensuring uniform heating of the sample.
Reaction control: By adjusting the air flow rate, the oxidation rate or reaction degree can be controlled.

2. Operation points
Furnace tube selection and sealing
Choose alloy tubes, quartz tubes, or corundum tubes that are resistant to high temperatures and oxidation (with a maximum temperature of 1600 ℃).
Both ends are sealed with rubber plugs or flanges to ensure airtightness and prevent air leakage or external pollution.

Air circulation design
Natural convection: Open at both ends, relying on natural air flow (suitable for low temperature or low oxygen demand experiments).
Forced ventilation: Air is introduced from one end through an air pump or compressed air tank, and exhaust gas is discharged from the other end (flow rate needs to be controlled). For example, activated carbon regeneration requires air calcination at 500-900 ℃ to remove adsorbed organic matter.

Coordinated control of temperature and atmosphere
Heating program: segmented heating (such as 2 ℃/min to 300 ℃, holding for 10 hours) to avoid sample cracking or furnace tube damage caused by thermal stress.
Atmosphere protection switching: If an inert atmosphere (such as nitrogen or argon) is required, the air must be exhausted before heating; When air is used for calcination, the opposite is true.

safety protection
Exhaust emissions are discharged outdoors or into fume hoods to prevent the accumulation of toxic gases (such as CO).
Equipped with over temperature alarm and power-off protection to prevent furnace tube overheating and rupture.

3. Typical application scenarios
material synthesis
Preparation of metal oxides: such as calcination of calcium carbonate to generate calcium oxide (800-900 ℃).
Ceramic sintering: Titanium dioxide transforms from amorphous form to rutile phase (400-600 ℃) or rutile phase (≥ 800 ℃).

Heat treatment and modification
Activated carbon regeneration: 500 ℃ air calcination can restore adsorption performance and remove pollutants from pores through oxidation.
Lithium battery material: The positive electrode material of lithium iron phosphate needs to be calcined in argon gas at 750 ℃, and then subjected to surface oxidation treatment with air.

chemical analysis
Sample ashing: Organic matter is completely burned under air at 500-600 ℃, leaving inorganic ash for elemental analysis.
Catalyst activation: Air calcination can remove impurities adsorbed on the surface of the catalyst and restore active sites.

4. Precautions
Avoid insufficient oxygen supply: If the sealing at both ends of the furnace tube is too tight, poor air circulation can lead to incomplete oxidation of the sample (such as only surface oxidation of the metal).
Prevent thermal shock: After high temperature, it is necessary to naturally cool down to below 200 ℃ before opening the furnace to avoid the furnace tube from bursting due to rapid cooling.
Cleaning and maintenance: Regularly clean the furnace and furnace tubes to prevent residues from affecting the experiment or corroding the furnace body.

High temperature tube furnace with a temperature of up to 1600 ℃ (click on the picture to view product details)

In general, using a tube furnace to air calcine materials can handle many processes. Before choosing, you can communicate with relevant technical personnel about the parameters you want, so as to customize a tube furnace that is more suitable for your own experiment or production!Click to learn more tube furnaces! Or click on online customer service to learn more about product information!