As a key equipment for material heat treatment and synthesis, the stability of vacuum atmosphere tube furnace directly affects the accuracy of experimental data and sample quality. A scientific maintenance system can significantly extend the service life of equipment. The following provides a detailed explanation of maintenance points from three aspects: daily operation, periodic maintenance, and emergency response.
1、 Immediate maintenance after daily operation
After each experiment, basic maintenance should be carried out immediately: when the furnace temperature drops below 100 ℃, slowly fill high-purity nitrogen to break the vacuum and prevent oxygen from flowing back and corroding the heating element under hot conditions. Wear insulated gloves when removing the quartz tube to avoid breakage caused by temperature difference stress. Use a dust-free cloth dipped in anhydrous ethanol to wipe the inner wall of the furnace and the outer surface of the quartz tube, with a focus on removing volatile matter crystals. Check if there are any particles or impurities embedded in the O-ring of the sealing flange. If there are slight indentations, apply vacuum silicone grease for repair. The control software needs to execute the "shutdown purge" program to replace residual gas.
2、 Periodic deep maintenance plan
（1） Monthly routine maintenance
1. Vacuum system maintenance: Disassemble the front stage pipeline of the diffusion pump and replace the molecular sieve desiccant; Check the oil level of the mechanical pump. If the color darkens, replace the dedicated vacuum pump oil.
2. Heating unit detection: Use a multimeter to measure the resistance of the heating wire. If the deviation exceeds ± 5%, it needs to be replaced; Calibrate the PID parameters of the temperature control module to ensure that the temperature rise curve has an error of less than ± 3 ℃ compared to the set value.
3. Inspection of the gas system: Activate each gas channel in sequence, use soapy water to test the air tightness of the solenoid valve and joint, and conduct a pressure decay rate of less than 0.5kPa/min during the pressure holding test.
（2） Quarterly in-depth maintenance
1. Regeneration treatment of quartz tube: Soak the used quartz tube in hydrofluoric acid solution (concentration 5%) for 2 hours, ultrasonically shake to remove stubborn deposits, and then rinse with deionized water until pH is neutral.
2. Replacement of sealing components: Mandatory replacement of flange sealing rings and observation window rubber gaskets, new accessories need to be pre aged for 8 hours in a vacuum environment in advance.
3. Cleaning of circulating water cooling system: Remove and wash the water tank filter, replace the coolant and add preservatives, and test whether the water pump flow meets the equipment calibration value.
3、 Common fault emergency handling
1. Insufficient vacuum degree: Prioritize checking the efficiency of the vacuum pump. If the ultimate vacuum is below 1 × 10 ⁻ ³ Pa, replace the pump oil and clean the exhaust port; Next, investigate the wear of the sealing ring.
2. Temperature runaway: Immediately cut off the main power supply, check if the thermocouple is detached or short circuited, and replace it with an S-type thermocouple of the same model if necessary.
3. Gas leakage: The segmented pressure holding method is used to locate the leakage point, with a focus on checking the valve interface and observation window sealing. Low temperature wax can be used temporarily to seal the emergency.
4、 Long term management suggestions
Establish equipment file cards to record maintenance time, replacement of parts, and abnormal situations. It is recommended to adopt a "three shift" rotation system to avoid continuous overload operation. Conduct a full load simulation test once a month to verify the stability of the equipment under special conditions. Through preventive maintenance, the equipment overhaul cycle can be extended to more than three years, ensuring the continuity of scientific research and production.