1Multi zone tube furnacePre-operation preparation
Equipment inspection
Furnace body and sealing: Check whether the furnace tube, flange interface, and sealing ring are intact, without cracks or aging. After vacuuming (≤ 10 ⁻ ² Pa) and holding for 30 minutes, observe whether the vacuum degree is stable and confirm that there is no leakage.
Electrical system: Confirm that the power and grounding wires are securely connected and not exposed or damaged. Check if the control panel display is normal.
Gas pipeline: Check if the pressure of the gas cylinder (≥ 0.5MPa), pressure reducing valve, and flow meter are normal, and if there is no leakage in the pipeline (check the joint with soapy water).
Cooling system: Confirm that the circulating water pressure (≥ 0.2MPa), water temperature (≤ 30 ℃), and cooling water pipes are not blocked.
Sample preparation
Size and position: Sample length ≤ 60% -80% of the effective heating zone length of the furnace tube, diameter ≤ 80% of the inner diameter of the furnace tube. Use high-temperature resistant lifting equipment (such as quartz or mullite rods) to suspend vertically in the center, with a distance of ≥ 20mm from the inner wall of the furnace tube.
Cleaning treatment: Remove oil stains and oxides from the surface of the sample to avoid contaminating the furnace tube.
Parameter preset
Heating program: Set the heating rate in sections (such as room temperature → 300 ℃/5 ℃/min → 600 ℃/3 ℃/min → 1000 ℃), with clear target temperature and time for each section.
Insulation time: Set the insulation time for key temperature points according to process requirements (such as 1 hour for rubber extrusion and 2 hours for sintering).
Atmosphere control: Select inert gas (N ₂/Ar), reducing gas (H ₂), or vacuum mode, and set the flow rate (such as H ₂ 200mL/min).
Cooling rate: Set according to material characteristics (such as ceramic ≤ 15 ℃/min, metal ≤ 25 ℃/min).
2、 Standardized operating procedures
Assembly and sealing of furnace body
Place the furnace tube symmetrically in the center of the furnace, place the sample in the middle of the furnace tube, and install tube plugs at both ends.
Install in the order of inner flange sleeve, sealing ring, pressure ring, sealing ring, and outer flange sleeve, tighten 3 hex screws to ensure that the flange does not deflect.
Gas path connection and leak detection
Vacuum mode: Close the intake valve, connect the mechanical pump, evacuate to ≤ 10 ⁻ ² Pa, and then close the exhaust valve.
Atmosphere mode:
Blow with inert gas (N ₂/Ar) for 10 minutes at a flow rate of 500mL/min to remove air from the furnace.
When using hydrogen gas, it is necessary to use soapy water to detect leaks at all joints. After confirming that there are no leaks, slowly open the main valve of the gas cylinder and adjust the outlet pressure to 0.1MPa.
Heating stage
Turn on the power, select the preset program, and confirm that each temperature zone starts synchronously.
Low temperature range (<500 ℃): Slowly increase the temperature (≤ 5 ℃/min) to avoid thermal stress cracking of the sample.
High temperature range (>500 ℃): Adjust the rate according to the material (e.g. semiconductor wafer ≤ 3 ℃/min).
Real time monitoring of temperature curves to ensure a deviation of ≤ ± 5 ℃ in each temperature zone (≤ ± 3 ℃ in steady state).
insulation stage
After reaching the target temperature, the system automatically switches to insulation mode, and the power output decreases to the required value to maintain the temperature.
Regularly record temperature data (every 10 minutes) to ensure no significant fluctuations.
Dynamic adjustment of atmosphere:
Reduction process (such as metal reduction): The insulation stage is switched to H ₂, the flow rate is increased to 300mL/min, and the oxygen content is ≤ 10ppm.
Oxidation process (such as ceramic sintering): Introduce O ₂ at a flow rate of 100mL/min and control the oxygen partial pressure.
cooling phase
Natural cooling: Turn off the heating power, maintain the atmosphere or vacuum state, and avoid oxidation.
Ceramic material: cooling rate ≤ 15 ℃/min.
金属材料：降温速率≤25 ℃/min。
Forced cooling (optional):
When rapid cooling is required, turn on the air or water cooling system, but ensure that the sample can withstand thermal shock.
When the temperature drops below 200 ℃, air can be introduced to accelerate cooling (it needs to be confirmed that the material has no oxidation risk).
Termination operation: After the temperature drops below 100 ℃, turn off the gas supply and release the vacuum (if applicable).
3、 Key control points and safety regulations
temperature control
Overtemperature protection: Set an overtemperature alarm threshold (such as 1100 ℃), which will automatically power off upon triggering.
Temperature zone coordination: The multi temperature zone furnace body needs to ensure that the temperature difference between adjacent temperature zones is ≤ 10 ℃ (during heating), and ≤ 5 ℃ in steady state.
Atmosphere management
Anti backflow design: Install a one-way valve in the gas pipeline to prevent gas backflow in the furnace during gas shutdown.
Oxygen content monitoring: In the reduction process, real-time monitoring of oxygen content is carried out, and when it exceeds the limit (>50ppm), it automatically switches to N ₂ blowing.
safety protection
Personal protection: Wear a protective face mask, heat-resistant gloves, and heat-resistant shoes during operation.
Emergency response:
Leakage: Immediately close the gas cylinder, evacuate personnel, ventilate and conduct maintenance.
Overtemperature: Press the emergency shutdown button, cut off the power, and start the cooling system.
Fire: Use dry powder fire extinguishers and prohibit using water to extinguish electrical fires.
4、 Post operation maintenance
Furnace cleaning: After the furnace has cooled to room temperature, wipe the inner wall of the furnace tube with a soft cloth to remove any residue.
Thermocouple calibration: Calibrate with a standard thermocouple every 3 months, and replace if the error exceeds ± 1.5 ℃.
Sealing ring replacement: Check the elasticity of the sealing ring every 6 months, and replace it immediately if it ages or cracks.
Record archiving: Save operation logs (temperature curves, gas flow rates, abnormal events) for easy traceability and analysis.
5Multi zone tube furnaceTypical application scenario examples
Electronic ceramic sintering
Heating program: Room temperature → 5 ℃/min to 600 ℃ (holding for 1 hour) → 3 ℃/min to 1100 ℃ (holding for 2 hours).
Atmosphere control: Apply N ₂ before 600 ℃ and switch to N ₂ - H ₂ mixture (H ₂ 5%) after 600 ℃.
Cooling rate: ≤ 10 ℃/min, natural cooling after reaching 200 ℃.
Metal heat treatment
Heating program: Room temperature → 10 ℃/min to 500 ℃ (insulation for 0.5h) → 5 ℃/min to 850 ℃ (insulation for 1h).
Atmosphere control: Ar is used throughout the entire process, with an oxygen content of ≤ 5ppm.
Cooling rate: ≤ 20 ℃/min, water cooling after reaching 300 ℃.