Precautions for using customized experimental tube furnace

During the use of customized experimental tube furnaces, it is necessary to strictly follow the operating specifications, ensuring experimental safety and equipment lifespan from four dimensions: early preparation, operation control, safety protection, and later maintenance. The following are specific precautions and instructions:

1. Preliminary preparation
Equipment inspection
Appearance integrity: Check whether there are cracks or looseness in the furnace tube, furnace shell, sealing ring, and gas interface to avoid accidents caused by high temperature leakage.
Electrical system: Confirm that the power cord is not damaged and the grounding wire is reliably connected to prevent the risk of leakage.
Gas pipeline: Check whether the gas pipeline valves, flow meters, and purification devices are normal. Flammable gases such as hydrogen need to be equipped with flashback arresters.
Samples and containers
Sample size: Ensure that the sample size is ≤ 80% of the inner diameter of the furnace tube to avoid blockage or uneven heating.
Container adaptation: Select the crucible material according to the sample type (such as quartz crucible ≤ 1200 ℃, alumina crucible ≤ 1800 ℃), and confirm that the container is compatible with the furnace tube.
Placement method: Powder samples should be evenly spread out, and block samples should be fixed at the center of the crucible to avoid tilting or contacting the furnace wall.
Atmosphere pre-treatment
Inert atmosphere: Introduce nitrogen or argon gas (flow rate 50-200 sccm) in advance and maintain for 10-30 minutes to eliminate air.
Vacuum environment: Start the vacuum pump to a pressure of ≤ 10 ⁻³ Pa, close the valve and fill it with protective gas to avoid oxidation.
Reductive atmosphere: Hydrogen gas needs to be purified by a purifier (purity ≥ 99.999%) and rigorously tested for airtightness.

2. Operation control
temperature program
Segmented heating: Set up multiple heating curves according to experimental requirements (such as 5 ℃/min rising to 800 ℃, holding for 1 hour and then 10 ℃/min rising to 1600 ℃).
Avoid thermal shock: Rapid heating (≥ 20 ℃/min) may cause cracking of the furnace tube or sample, and the rate should be adjusted according to the material’s thermal expansion coefficient.
Real time monitoring: Observe the temperature curve through a temperature controller. If there are abnormal fluctuations (such as ± 5 ℃ or above), immediately stop the machine for inspection.
Atmosphere regulation
Gas flow rate: Adjust the flow rate according to experimental requirements (such as 10-50 sccm for hydrogen reduction and 50-200 sccm for inert protection).
Atmosphere switching: It should be carried out after cooling to a safe temperature (such as ≤ 300 ℃) to avoid danger caused by gas reactions at high temperatures.
Pressure control: During pressure sintering, it is necessary to slowly increase the pressure to the target value (such as 5MPa) and monitor the pressure gauge in real time.
Cooling treatment
Natural cooling: Conventional experiments can cool down naturally to room temperature after turning off the power.
Rapid cooling: It is necessary to activate the water-cooled jacket or air-cooled system, but the cooling rate should be controlled (such as ≤ 10 ℃/min) to prevent sample cracking.
Atmosphere maintenance: During the cooling process, it is necessary to continuously introduce protective gas to prevent sample oxidation.

3. Security protection
Personal Protection
When operating high-temperature equipment, it is necessary to wear insulated gloves, goggles, and lab coats to avoid direct contact with the furnace body or hot samples.
Fire extinguishers must be equipped in areas where flammable gases such as hydrogen are operated, and open flames or static electricity are strictly prohibited.
Emergency treatment
Temperature out of control: Immediately press the emergency stop button, cut off the power, and introduce a large amount of inert gas to cool down.
Gas leakage: Close the gas source valve, open the ventilation system, evacuate personnel to a safe area, and contact maintenance.
Furnace tube rupture: Immediately shut down and evacuate personnel to prevent high-temperature debris from splashing and injuring people.
Environmental requirements
The equipment should be placed in a well ventilated laboratory without corrosive gases, with a reserved operating space of ≥ 50cm around it.
Do not stack flammable materials or conduct other high-temperature experiments near the equipment.

4. Post maintenance
Daily cleaning
After the experiment is completed and the furnace body is cooled to ≤ 50 ℃, wipe the inner and outer walls of the furnace tube with a soft cloth to avoid residual corrosion of the furnace tube.
Regularly clean the gas pipeline filter to prevent impurities from clogging.
component replacement
Heating element: If the resistance wire is found to be broken or aged (such as a decrease in heating rate of more than 20%), it should be replaced in a timely manner.
Furnace tube: When cracks, deformation, or thickness reduction of ≥ 20% occur, it needs to be replaced to avoid bursting at high temperatures.
Sealing ring: Check the sealing performance every 6-12 months, and replace it immediately if it ages or deforms.
periodic calibration
Every six months, a professional organization is commissioned to calibrate the temperature controller to ensure that the temperature display error is ≤ ± 1 ℃.
Inspect the performance of the vacuum pump annually to ensure that the maximum vacuum degree is ≤ 10 ⁻ ³ Pa.

5. Summary and Suggestions
Strictly follow the operating procedures: carefully read the equipment manual and receive professional training before the experiment.
Regular maintenance and calibration: Establish equipment maintenance records, record information such as replacement parts and calibration time.
Choose reliable suppliers: Prioritize manufacturers with ISO certification and over 10 years of industry experience to ensure the quality of after-sales service.
By standardizing operations and regular maintenance, the service life of tube furnaces can be significantly extended, experimental risks can be reduced, and research efficiency can be improved.