How to choose a high-temperature tube furnace for small experiments?

When choosing a high-temperature tube furnace for small-scale experiments, it is necessary to comprehensively evaluate core dimensions such as temperature range, heating elements, furnace tube size and material, temperature zone design, functional scalability, vacuum and atmosphere system, brand and after-sales service, and make decisions based on experimental needs, budget, and long-term usage costs. The following is a specific analysis:

1. Temperature range matched with heating element
Temperature range selection
Basic experiment: If dealing with metal oxides or ordinary ceramics, choosing a tube furnace below 1200 ℃ can meet the requirements.
High temperature material processing: If high-temperature ceramics such as silicon carbide and silicon nitride need to be processed, a tube furnace above 1600 ℃ should be selected to ensure complete sintering of the materials.
Key point: Avoid excessive temperature redundancy, as a high temperature range may lead to a significant increase in equipment costs. At the same time, it is necessary to confirm whether the heating element material is compatible with the process material.
Heating element type
Fe Cr Al/Ni Cr Al alloy: suitable for 250-1250 ℃, low cost, but prone to oxidation at high temperatures and short lifespan.
Silicon carbide (SiC): suitable for 1300-1600 ℃, high thermal conductivity, fast heating, but relatively high price.
MoSi ₂ (Molybdenum Disilicide): Suitable for 1600-1800 ℃, with strong oxidation resistance, but it is forbidden to heat it below 800 ℃ for a long time, otherwise it is prone to powdering.
Suggestion for selection: Choose the corresponding components based on the experimental temperature, for example, MoSi ₂ components should be selected for the 1600 ℃ experiment, and avoid long-term operation at low temperatures.

2. Sample of furnace tube size and material adaptation
Selection of furnace tube size
Sample volume: Select the inner diameter and length of the furnace tube based on the sample size. For example, when processing long strip samples, a long furnace tube (such as 1200mm) should be selected, while when processing powder samples, a short furnace tube (such as 600mm) can be selected.
Loading method: If frequent loading and unloading of samples is required, an open type furnace tube (such as side opening or top opening) can be selected to improve operational convenience.
Key point: The inner diameter of the furnace tube should be 20% -30% larger than the sample diameter to avoid overloading and affecting temperature uniformity.
Material selection of furnace tube
Quartz tube: suitable for experiments below 1200 ℃, with good transparency and easy observation of samples, but prone to deformation at high temperatures.
Corundum tube (alumina): suitable for experiments below 1800 ℃, resistant to high temperature and corrosion, but with a higher price.
Stainless steel furnace tube: suitable for experiments below 1000 ℃, low cost, but prone to oxidation at high temperatures, requiring the use of inert gas.
Selection suggestion: Choose the corresponding material according to the experimental temperature, for example, corundum tube should be selected for the 1600 ℃ experiment, and quartz tube can be selected for experiments below 1200 ℃.

3. Temperature zone design and temperature uniformity
Single temperature zone vs multi temperature zone
Single temperature zone: suitable for simple experiments, temperature uniformity depends on furnace tube design, and the temperature difference in the central area may reach ± 5 ℃.
Multi temperature zone: suitable for complex processes (such as gradient sintering), different temperature zones can be set, and the length of the constant temperature zone is longer (such as the three temperature zone constant temperature zone can reach 300mm), but the equipment cost is higher.
Suggestion for selection: If precise temperature gradient control is required (such as crystal growth), choose a multi zone furnace; If the experiment is simple, a single temperature zone furnace can meet the requirements.
Temperature uniformity optimization
Furnace tube design: Choose furnace tubes with multi-layer insulation screens and temperature control zones to reduce temperature gradients.
Rotation function: If uniform heat treatment of powder samples is required, a rotary tube furnace can be selected to rotate the furnace tube to make the sample heated more evenly.
Key point: Temperature uniformity directly affects experimental results, for example, excessive temperature difference during material sintering may lead to cracking.

4. Functional scalability meets diverse needs
Atmosphere control system
Inert gas protection: To avoid sample oxidation, choose a tube furnace equipped with a gas flow meter, which can accurately control the flow rate of gases such as nitrogen and argon.
Vacuum system: If a high vacuum environment (such as ≤ 10 ⁻ ³ Pa) is required, choose a tube furnace equipped with a molecular pump or diffusion pump, which is suitable for the treatment of oxidation sensitive materials.
Special gas treatment: If hydrogen reduction or corrosive gas experiments are required, choose a tube furnace with explosion-proof design and gas purification function.
Selection suggestion: Choose the corresponding function according to the experimental atmosphere requirements, such as inert gas protection for metal heat treatment and high vacuum environment for semiconductor material growth.
Rapid Heat Treatment (RTP)
Functional features: RTP tube furnace can achieve second level heating/cooling, suitable for experiments that require rapid thermal cycling such as thin film deposition and phase transition research.
Suggestion for selection: If high-frequency heat treatment or research on material dynamic response is required, choose RTP tube furnace; If the experiment does not require a high heating rate, a regular tube furnace is sufficient.

5. Stability of Vacuum and Atmosphere Systems
Vacuum system selection
Mechanical pump+Roots pump: suitable for low vacuum (10 ⁻¹ -10 ⁻ ² Pa), low cost, but slow pumping speed.
Molecular pump+diffusion pump: suitable for high vacuum (10 ⁻² -10 ⁻³ Pa), with fast pumping speed, but requires a front-end pump (such as a mechanical pump).
Selection suggestion: Choose the corresponding system according to the experimental vacuum requirements, such as high vacuum for metal welding and low vacuum for ordinary annealing.
Atmosphere leakage rate control
Sealing design: Choose furnace doors with fluororubber or metal sealing rings to ensure a stable atmosphere inside the furnace. For example, a double-layer water-cooled furnace shell design can reduce the impact of thermal radiation on the seal.
Detection method: The leakage rate of the furnace body is detected by a helium mass spectrometer leak detector, and the leakage rate of high-quality furnace bodies should meet a certain standard.
Key point: Atmosphere leakage may cause sample oxidation or contamination, and the leakage rate needs to be strictly controlled.

6. After sales service guarantee
Installation and commissioning: Select suppliers who provide on-site installation and commissioning to ensure the normal operation of the equipment.
Training services: Choose suppliers that provide operational training to improve the operational skills of laboratory personnel.
Spare parts supply: Select suppliers who reserve key spare parts such as heating elements and sealing rings to reduce downtime.
Response time: Choose a supplier that promises to respond within 24 hours, for example, Luoyang Zhuoxin encountered unstable gas flow during the debugging phase, and the engineer rushed to the site on the same day to solve it.