Can a high-temperature vertical tube furnace be evacuated?

The high-temperature vertical tube furnace can be evacuated, and its principle and operating points are as follows:

1. Vacuum pumping principle
The high-temperature vertical tube furnace is connected to a vacuum pump system to extract gas from the furnace to reduce pressure and create an oxygen free or low oxygen environment. The core principles include:
Mechanical pump vacuum pumping: By using a combination of rotary vane vacuum pump or Roots pump, the pressure inside the furnace is pumped to extremely low levels (such as a maximum vacuum degree of 5 × 10 ⁻ ² Pa to 1 × 10 ⁻ ⁵ Pa) to meet the process requirements of metal degassing, ceramic sintering, etc.
Atmosphere replacement: After vacuuming, inert gases such as nitrogen and argon can be introduced to further eliminate residual oxygen and prevent material oxidation. For example, in semiconductor device manufacturing, it is necessary to ensure the purity inside the furnace through multiple vacuum filling cycles.

2. Key components and functions
Vacuum system:
Vacuum pump: equipped with a two-stage rotary vane pump or Roots pump combination, with a pumping speed of 50L/s to 200L/s, quickly achieving the required vacuum degree.
Vacuum gauge: The digital vacuum gauge has an accuracy of ± 1 × 10 ⁻ ³ Pa and can monitor the air pressure inside the furnace in real time.
Pressure holding valve: automatically maintains the vacuum degree to avoid pressure fluctuations affecting the process.
Furnace structure:
Double stainless steel shell: the outer layer is sprayed with high temperature resistant coating, and the inner layer is filled with alumina fiber+nano aerogel composite insulation layer. The surface temperature is controlled within 70 ℃, and the heat loss is reduced.
Vertical heating tube: Made of high-purity alumina ceramic tube, with a temperature resistance of 1700 ℃ and excellent chemical stability, avoiding reaction with the sample.
Sealing flange: Made of 316L stainless steel material, with nickel plating treatment on the surface, matched with O-ring rubber seal to ensure vacuum sealing.

3. Operation process and precautions
Vacuum extraction steps:
Close all valves, start the vacuum pump, and open the vacuum valve.
Observe the pressure gauge and wait for the vacuum degree to stabilize at the set value before closing the vacuum valve and pump.
Introduce inert gas (such as nitrogen) to atmospheric pressure and repeat the vacuum inflation cycle 2-3 times to improve purity.
Key parameter control:
The air pressure inside the furnace tube shall not exceed 0.02MPa (absolute pressure) to prevent equipment damage.
High temperature limit: When the temperature exceeds 900 ℃, the furnace tube needs to maintain a normal pressure state to avoid vacuum induced tube rupture.
Valve operation: After vacuuming, the vacuum valve should be closed first, and then the pump should be turned off to prevent air backflow.
Security protection:
Over temperature protection: Automatically shuts off when the temperature exceeds the set value.
Overpressure alarm: An alarm is triggered when the air pressure is abnormal.
Leakage protection: Power off immediately when the leakage current is ≤ 30mA.

4. Application scenarios
Materials Science:
New ceramic sintering: prevents oxidation under vacuum or inert atmosphere to ensure material properties.
Nanomaterial synthesis: Achieving uniform growth of nanoparticles through precise control of the atmosphere.
Semiconductor industry:
Silicon wafer annealing: Relieve stress and improve device reliability in a hydrogen or nitrogen atmosphere.
Photoresist curing: vacuum environment reduces bubble generation and improves coating quality.
Metallurgical field:
Metal diffusion welding: achieving high-strength bonding between metals under vacuum.
Powder metallurgy sintering: using inert gas protection to prevent powder oxidation.