Tube furnaces can be categorized into several different temperature ranges based on their design specifications, heating methods, and application scenarios. Different types of tube furnaces are suitable for diverse needs, ranging from low temperatures to ultra-high temperatures. The following provides a detailed explanation of temperature classification, typical applications, and influencing factors.

Temperature Range Classification of Tube Furnaces
Depending on the design objectives and application scenarios, the temperature range of tube furnaces can be divided into the following categories:

Conventional Temperature Tube Furnaces: These typically have a temperature range of room temperature to 1200°C and are the most common type of commercial tube furnace. They are suitable for most routine experimental needs, such as heat treatment, sintering, catalytic reactions, and material synthesis. For example, the tube furnace has a temperature control range of room temperature to 1200°C and an operating temperature of ≤1100°C.

Medium Temperature Tube Furnaces: Some references mention medium temperature tube furnaces with an operating temperature range of 500°C to 1200°C. These are primarily used in industrial applications such as metal heating, glass forming, and ceramic sintering. Their temperature range overlaps somewhat with conventional temperature tube furnaces.
High-temperature tube furnaces: By utilizing high-temperature-resistant materials such as ceramic fiber and graphite and optimizing heating methods, they can reach maximum temperatures of 1600°C or even higher. They are suitable for high-temperature applications, such as ceramic material preparation, high-temperature catalytic reactions, and specialty alloy melting.

Low-temperature tube furnaces: Less common, they can reach temperatures as low as -196°C (liquid nitrogen temperature) and are primarily used for chemical reaction and material property research in extremely low-temperature environments, such as superconductor characterization.

Key Factors Affecting the Temperature Range of Tube Furnaces
The actual operating temperature range of a tube furnace is not fixed but is influenced by a combination of factors:

Furnace Material: The maximum temperature is directly determined by the high-temperature resistance of the furnace chamber material. For example, ceramic fiber furnace chambers are suitable for medium- and high-temperature conditions (≤1400°C), while graphite furnace chambers can support ultra-high temperatures (>1600°C).

Heating Method: Resistance heating is commonly used for conventional temperature applications (≤1200°C). Induction heating or microwave heating can achieve higher heating rates and higher temperature limits. Temperature Control System: A high-precision PID controller (e.g., ±1°C constant temperature fluctuation) ensures temperature stability and prevents temperature fluctuations from affecting experimental results. This is especially important under extreme high or low temperature conditions.

Vacuum and Atmosphere Environment: Vacuum tube furnaces require consideration of the high-temperature resistance of the sealing material. The introduction of oxidizing or reducing gases may affect the furnace life and indirectly limit the long-term operating temperature.