Precautions for using heat treatment tube furnace

As a key equipment in high-temperature experiments and industrial production, the operation of heat treatment tube furnace involves complex environments such as high temperature, high pressure, and special atmosphere. Improper use may lead to equipment damage, experimental failure, and even safety accidents. The following are the key precautions when using a heat treatment tube furnace, covering four aspects: preparation before operation, monitoring during operation, maintenance and safety protection:

1. Preparation before operation: Ensure that the equipment and materials are compatible
Equipment inspection and calibration
Appearance inspection: Confirm that there are no cracks or deformations in the furnace body, and that the furnace door is well sealed to avoid gas leakage or heat loss at high temperatures.
Temperature system calibration: Use standard thermometers (such as platinum rhodium thermocouples) to verify the temperature uniformity inside the furnace, ensuring that the temperature deviation in the effective heating zone is within ± 5 ℃.
Atmosphere system testing: Check whether the gas pipeline connection is firm, the valve opening and closing are flexible, and the leakage rate should be less than 0.1%/min (which can be detected by soap water).
Material compatibility assessment
Temperature resistance: Confirm that the melting point of the sample material is below the upper limit of the furnace temperature (if ceramic sintering requires a safety margin of 50-100 ℃), to avoid melting and damaging the furnace tube.
Chemical stability: If corrosive gases (such as Cl ₂, H ₂ S) are used, corrosion-resistant furnace tubes (such as quartz tubes that require a protective layer) or corundum tubes should be used instead.
Size matching: The sample size should be less than 80% of the inner diameter of the furnace tube to avoid blocking the gas flow channel.
Process parameter setting
Heating curve: Set the heating rate in segments according to the material characteristics (such as synthesis of nanomaterials requiring ≤ 5 ℃/min to prevent grain coarsening).
Insulation time: Ensure that the sample fully reacts (e.g. ceramic sintering requires insulation for 2-4 hours to eliminate pores).
Cooling method: Control the cooling rate (for example, metal quenching requires rapid cooling, while ceramics need to be naturally cooled in the furnace to prevent cracking).

2. Running monitoring: real-time response to abnormal situations
Temperature monitoring and adjustment
Multi point temperature measurement: Install thermocouples at the front, middle, and rear ends of the furnace tube to monitor temperature uniformity in real-time. If the deviation exceeds the set value, adjust the heating power or check the position of the thermocouple.
Overtemperature protection: Set a temperature upper limit alarm (such as setting the upper limit of 1700 ℃ furnace temperature to 1750 ℃), and immediately cut off the heating power after triggering the alarm.
Atmosphere control and leak detection
Gas flow stability: Monitor gas flow rate through a mass flow meter, with a fluctuation range of ≤± 1% FS (e.g. fluctuation ≤ 5 sccm when N ₂ flow rate is 500 sccm).
Oxygen content monitoring: In inert atmosphere treatment, use an oxygen analyzer to detect the oxygen concentration in the furnace, which should be below 10ppm (oxygen content can be reduced by introducing excess reducing gas).
Emergency response for leaks: If a gas leak is found, immediately turn off the gas source, turn on the ventilation system, evacuate personnel to a safe area, and contact maintenance.
Abnormal response of equipment status
Abnormal noise: If abnormal noise is heard from the furnace tube or heating element, it may cause cracking due to thermal stress, and the machine should be stopped immediately for inspection.
Current fluctuation: Abnormal fluctuations in heating element current (such as ± 10% or more) may be due to poor contact or component aging, and the machine needs to be stopped for replacement.
Vacuum degree decrease: If the pressure rise rate of the vacuum furnace exceeds 0.1Pa/min, it may be due to seal failure, and the status of the furnace door O-ring or vacuum pump needs to be checked.

3. Maintenance and upkeep: Extend equipment lifespan
Daily cleaning and lubrication
Furnace tube cleaning: After each experiment, wipe the inner wall of the furnace tube with a dust-free cloth to remove sample residues (such as carbon deposition, which needs to be neutralized after cleaning with hydrofluoric acid).
Lubrication of transmission components: Add high-temperature lubricating grease (such as molybdenum disulfide grease) to the gears and bearings of the rotary tube furnace every 3 months to reduce wear.
Regular calibration and replacement
Thermocouple calibration: Calibrate thermocouples with a standard temperature source every 6 months, and replace them if the error exceeds ± 1 ℃.
Gas filter replacement: Replace the gas filter every 100 samples processed or every 3 months to prevent impurities from clogging the pipeline.
Furnace tube replacement: If there are cracks, deformations, or a thickness reduction of more than 30% in the furnace tube, it needs to be replaced immediately (such as a quartz tube with a lifespan of about 200 high-temperature cycles).
Long term disuse protection
Dry storage: Before discontinuation, raise the furnace temperature to 100 ℃ and dry for 2 hours to remove moisture before turning off the power.
Dust cover: Cover the furnace body with a dust cover to prevent dust from entering and affecting the insulation performance.
Regular power on: Power on once every 3 months (set to run at a low temperature of 50 ℃ for 2 hours) to prevent electrical components from getting damp.

4. Security protection: Avoiding operational risks
Personal protective equipment
High temperature protection: Wear insulated gloves (temperature resistance ≥ 500 ℃) and protective face shields during operation to prevent burns.
Gas protection: When handling toxic gases (such as H ₂ S), operate in a fume hood and wear a gas mask.
Anti static measures: Before contacting the furnace body, touch the grounded metal to release static electricity and avoid sparks igniting flammable gases.
Emergency Response Plan
Fire response: If a fire breaks out in the furnace, immediately cut off the power and gas sources, and use a carbon dioxide fire extinguisher to extinguish the fire (water is prohibited).
Personnel burns: Immediately rinse the wound with running cold water for 15 minutes, apply burn ointment, and send to the hospital.
Gas poisoning: Quickly move the poisoned person to a well ventilated area, keep their respiratory tract clear, call the emergency number, and inform them of the type of gas.
Safety signage and training
Dangerous Area Identification: Post “High Temperature Danger” signs in high-temperature areas of the furnace (such as heating zones), and label the gas name and flow direction near the gas pipeline.
Operation training: New employees need to pass theoretical exams and practical assessments (such as independently setting the heating curve) before they can operate the equipment.