Common faults and solutions of corundum tube furnace

The common faults and solutions of corundum tube furnace are as follows:

1. Corundum tube fracture
reason:
Poor thermal shock resistance: Corundum material is not resistant to rapid cooling and heating, and a large temperature difference can easily lead to fracture.
Improper operation:
The heating and cooling rate is too fast (exceeding 5 ℃/min).
Directly cool naturally to room temperature at high temperatures.
High temperature sample delivery/sampling or low-temperature objects touching high-temperature furnace tubes.
Installation issues:
There are no brackets on both sides of the furnace tube, causing deformation and fracture due to gravity.
The flange did not use a support frame, and vertical stress caused fracture.
Gas and impurities:
Excessive airflow leads to large temperature differences.
Residual samples or impurities inside the furnace tube (such as metal debris, substances containing K ₂ O/Na ₂ O/CaO/SiO ₂).
Moisture and corrosion:
New furnace tubes or those that have not been used or baked for a long time (need to be baked at 300-400 ℃ for 5-6 hours).
Introduce corrosive gases such as sulfides and chlorides.
resolvent:
Control the heating and cooling rate:
Heating rate ≤ 10 ℃/min, cooling rate ≤ 15 ℃/min, recommended 5 ℃/min.
Set a cooling curve to avoid direct natural cooling.
Standardized operation:
The temperature during layout/sampling is ≤ 140 ℃.
Avoid touching high-temperature furnace tubes with low-temperature objects.
Optimize installation:
Brackets are added on both sides of the furnace tube, and flanges are supported by brackets.
Place insulation plugs (2 at each end, a total of 4) inside the furnace tube to form a balanced temperature field.
Cleaning and maintenance:
Regularly clean the inner wall of the furnace tube to avoid residual samples.
New furnace tubes or those that have not been used for a long time need to be baked to remove moisture.
Gas control:
Gas flow rate ≤ 200SCCM (or 200ml/min), avoid cold air flow impact.
Prohibit the introduction of corrosive gases.

2. Abnormal temperature control
reason:
Set problem:
Set the temperature too low or too high.
The temperature rise and fall rate setting is unreasonable.
Component malfunction:
Heating element damage (such as breakage).
The thermocouple or temperature controller is damaged.
Electrical connection:
The connection point of the heating element is loose or short circuited.
The fuse is blown or the fuse is damaged.
resolvent:
Check the set parameters:
Adjust the set temperature to a reasonable range.
Redesign the temperature rise and fall curve to ensure that the speed meets the requirements.
Replace faulty components:
Replace the broken heating element.
Replace damaged thermocouples or temperature controllers.
Check electrical connections:
Tighten the connection point of the heating element and eliminate the short circuit.
Replace the blown fuse or fuse.

3. Abnormal atmosphere control
reason:
Gas leakage:
The flange seal is not tight or the O-ring is aging.
The gas cylinder is not equipped with a pressure reducing valve or the pressure reducing valve is malfunctioning.
Abnormal air pressure:
The pressure gauge reading is abnormal (such as>0.02MPa).
Improper closure of exhaust/intake valves.
Gas flow rate:
Excessive flow leads to unstable temperature field.
resolvent:
Check the sealing:
Replace the aging O-ring or reinstall the flange.
Ensure that the gas cylinder is equipped with a pressure reducing valve (range 0.01MPa-0.1MPa).
Monitoring air pressure:
Always pay attention to the pressure gauge, and if it exceeds 0.02MPa, immediately open the relief valve.
Avoid closing the exhaust/intake valve to heat the sample.
Control traffic:
Limit gas flow rate to ≤ 200SCCM (or 200ml/min).

4. Electrical system malfunction
reason:
Power issue:
The plug is not properly plugged in or the power is off.
The fuse is blown or the control circuit fuse is damaged.
Abnormal instrument display:
The instrument has no power display or abnormal output.
The set temperature does not match the temperature inside the furnace.
resolvent:
Check the power supply:
Plug in the plug or connect the wire.
Replace the fuse or fuse.
Calibration instrument:
Replace the damaged temperature sensor or temperature controller.
Adjust the temperature measurement point position to ensure consistency with the layout point.

5. Vacuum system malfunction
reason:
Insufficient vacuum degree:
Insufficient oil line in the vacuum pump or air leakage in the vacuum system.
Electric butterfly valve has slow response or excessive diameter.
Internal structural leakage:
Abnormal water leakage caused by damage to the internal pipelines and interlayers of the furnace body.
resolvent:
Maintain the vacuum system:
Check the mechanical pump oil line to ensure it is above the marked line.
Replace the electric butterfly valve with an electric ball valve that responds slowly or has a large diameter.
Check the internal structure:
Inspect the airtightness of the furnace body section by section, repair or replace damaged parts.