What is the working principle of a vacuum annealing furnace?

The working principle of a vacuum annealing furnace mainly involves the process of high-temperature heating treatment of materials in a vacuum state. The following is a detailed explanation of the working principle:
1. Preparation of work environment
Establishment of vacuum environment:
The vacuum annealing furnace first reduces the pressure inside the furnace to a certain degree of vacuum state through a vacuum pump. This is to avoid reactions between the material and oxygen in the air during the heating process, which can lead to oxidation, hardening, and deformation.
The control of vacuum degree is crucial to ensure the annealing effect, and it is usually necessary to achieve a certain vacuum degree requirement before starting the heating process.
2. Heating process
Material placement:
The material to be processed is placed inside the vacuum chamber and the furnace door is closed to ensure sealing.
Heating device startup:
The heating device (such as electric heating tube, hot oil pump, etc.) starts working to heat the material. During the heating process, the temperature gradually increases to the desired annealing temperature.
Temperature control:
Accurate control of the heating process through a temperature control system ensures that the material undergoes annealing treatment within the set temperature range. The temperature control system can adjust the heating power and heating time as needed to meet the annealing requirements of different materials.
3. Annealing treatment
Insulation:
After the material reaches the required annealing temperature, it needs to be kept for a period of time for insulation treatment. The purpose of insulation is to homogenize the internal structure of the material and achieve or approach a state of equilibrium.
The length of insulation time depends on factors such as the type, shape, and annealing requirements of the material.
Gas removal:
When heating materials in a vacuum state, due to the thin gas inside the chamber, gases (such as hydrogen, oxygen, etc.) in the material will gradually be removed. This helps to reduce the impurity content in the material, improve the purity and strength of the material.
4. Cooling process
Slow cooling:
After annealing, the material needs to be slowly cooled to room temperature. The control of cooling rate is crucial for avoiding stress and deformation inside the material.
Cooling under vacuum can further reduce the chance of contact between the material surface and oxygen in the air, preventing oxidation reactions from occurring.
5. Summary
The vacuum annealing furnace optimizes the microstructure and improves the performance of materials by heating and insulating them at high temperatures under vacuum, and then slowly cooling them to room temperature. This processing method avoids problems such as oxidation, hardening, and deformation in traditional annealing processes, improving the quality and reliability of the material. At the same time, vacuum annealing furnaces also have the advantages of easy operation, significant energy-saving effect, continuous operation, safety and reliability, and have been widely used in fields such as metal processing, casting metallurgy, etc.