Tube muffle furnace

The tubular muffle furnace is a high-temperature experimental equipment that combines the design of a tubular furnace with the heating principle of a muffle furnace. Its core advantage lies in the precise control of the gas atmosphere through the tubular structure, while using resistance heating to provide a stable high-temperature field. The following analysis will be conducted from the dimensions of structure, function, application, and selection:

1. Core structure and working principle
Tubular furnace
Material: High temperature resistant ceramic pipes (such as corundum pipes, quartz pipes) or high-temperature alloy pipes are usually used, which can withstand high temperatures of 1200 ℃~1800 ℃ (depending on the material).
Design: The sample is placed in a constant temperature zone inside the tube and indirectly heated by an external heating element (such as a silicon carbide rod or resistance wire) to avoid direct contact between the sample and the heating element and reduce the risk of contamination.
Atmosphere control system
Vacuum function: Equipped with a vacuum pump (such as a rotary vane pump, molecular pump), it can reduce the vacuum degree inside the furnace to 10 ⁻ Pa or even higher, eliminate air or volatile gases, and prevent sample oxidation.
Gas injection: Inert gases (such as nitrogen and argon), reducing gases (such as hydrogen), or mixed gases are introduced into the furnace tube through gas flow meters, valves, and other components to maintain a specific reaction environment.
Temperature Control System
High precision temperature control: using thermocouples (such as K-type and S-type) and PID controllers to achieve precise control of heating rate and insulation time, temperature uniformity can reach within ± 5 ℃, and some models have temperature control accuracy of ± 1 ℃.
Program temperature control: Supports multi-stage intelligent temperature programming (such as 40 stages) to meet complex process requirements (such as staged heating, insulation, and cooling).
Safety protection device
Over temperature protection: When the temperature inside the furnace exceeds the set value, the power will be automatically cut off and an alarm will be triggered.
Gas leakage detection: Real time monitoring of gas pressure inside the furnace to prevent safety accidents caused by the leakage of flammable and explosive gases (such as hydrogen).

2. Core functional features
Dual control of vacuum and atmosphere
Vacuum environment: isolate air, avoid sample oxidation or introduction of impurities, and improve experimental purity.
Atmosphere regulation: By introducing different gases, a protective (such as inert gas) or reactive (such as reducing gas) atmosphere is created to meet specific process requirements.
High temperature stability and uniformity
High temperature range: It can stably maintain a high temperature of over 1000 ℃, and some models can reach 1800 ℃. It is suitable for processes such as ceramic sintering and metal melting.
Temperature uniformity: The tubular design combined with hot air circulation eliminates temperature gradients and ensures uniform heating of the sample.
Sample processing flexibility
Small batch processing: suitable for small-sized samples such as powders, flakes, and wires, and easy to observe or quickly take and place.
Continuous operation: supports continuous entry and exit of samples into the furnace, maintains temperature curve consistency, and improves production efficiency.
energy saving and environmental protection
Efficient heat exchange: Optimize furnace structure and insulation materials (such as ceramic fibers) to reduce heat loss and achieve high energy utilization efficiency.
Low emissions: The enclosed design reduces exhaust emissions and meets environmental requirements.

3. Typical application areas
Material sintering and preparation
Ceramic materials: Sintering non oxide ceramics such as silicon nitride and silicon carbide in an inert atmosphere to avoid high-temperature oxidation.
Composite materials: Prepare metal based composite materials in a reducing atmosphere (such as hydrogen nitrogen mixture) to prevent substrate oxidation.
heat treatment process
Vacuum annealing: Vacuum annealing is performed on precision metal parts such as bearings and cutting tools to eliminate internal stress and maintain surface smoothness.
Atmosphere quenching: Quenching steel in a specific gas atmosphere to control the thickness of the surface oxide layer and improve hardness uniformity.
Carbonization/Nitriding: Injecting carbon/nitrogen containing gas into the furnace to achieve surface infiltration treatment of the metal at high temperatures, enhancing wear resistance.
Semiconductor and Electronics Industry
Wafer processing: High temperature doping and oxidation of silicon wafers in vacuum or inert atmosphere to ensure surface cleanliness.
Electronic ceramics: When sintering piezoelectric ceramics and ferrite cores, the direction of grain growth is adjusted through atmosphere control to optimize electrical properties.
Chemical Analysis and Experimental Research
Material decomposition experiment: controlling the atmosphere environment to study the decomposition behavior and products of minerals and catalysts at high temperatures.
Aerospace material testing: Simulate harsh environments (such as vacuum or low-pressure atmospheres) to test the high-temperature stability and thermal shock resistance of spacecraft materials.

4. Key considerations for selection
temperature range
Select according to material processing requirements: Generally, metal heat treatment should be below 1200 ℃, while ceramic sintering should be above 1600 ℃.
Vacuum degree and atmosphere type
Vacuum requirements: Conventional vacuum requires a rotary vane pump system (10 ⁻³ Pa), while high vacuum requires a molecular pump (10 ⁻⁴ Pa).
Atmosphere type: When dealing with flammable and explosive gases (such as hydrogen), it is necessary to confirm the explosion-proof design of the equipment.
Furnace tube size
Select the pipe diameter (such as 50mm~200mm) and length according to the sample size to ensure that the sample can be uniformly heated.
temperature control accuracy
For temperature sensitive experiments (such as semiconductor doping), high-precision models within ± 1 ℃ should be selected.
degree of automation
Choose manual, semi-automatic, or fully automatic models according to your needs. Fully automatic equipment supports PLC control to improve operational efficiency.