What gases can be passed through a high-temperature gas vacuum tube furnace?

　　The high-temperature gas vacuum tube furnace can be filled with a variety of gases, including inert gases, reducing gases, oxidizing gases, and mixed gases, as follows: 1. Inert gas Nitrogen (N ₂) Purpose: To provide an anaerobic environment and prevent oxidation of materials such as metals and ceramics at high temperatures. Application scenarios: metal annealing, ceramic sintering, semiconductor material preparation, etc. Advantages: Low cost, easy to obtain, suitable for experiments with low purity requirements. Argon gas (Ar) Usage: As a high-purity inert protective gas, it prevents material oxidation or contamination. Application scenarios: aircraft engine blade annealing, carbon nanotube synthesis, high-purity metal purification, etc. Advantages: Stable chemical properties, suitable for experiments with high purity requirements. Helium (He) Purpose: As a backup protective gas, it can quickly fill the furnace cavity to respond to emergency situations. Application scenario: Emergency protection when replacing reaction tubes at high temperatures. Advantages: Good thermal conductivity, can quickly and uniformly maintain the temperature inside the furnace. 2. Reducing gas Hydrogen (H ₂) Usage: As a reducing agent, it removes oxygen from the surface of metal oxides or promotes reduction reactions. Application scenarios: Metal oxide semiconductor doping, catalyst preparation, etc. Attention: It is necessary to strictly control the concentration and flow rate to prevent the risk of explosion. Carbon monoxide (CO) Usage: As a reducing gas, it participates in specific chemical reactions. Application scenarios: High temperature reactions of chemical raw materials, synthesis of special materials, etc. Attention: Toxic gases require exhaust gas treatment equipment. 3. Oxidizing gas Oxygen (O ₂) Purpose: To provide an oxidizing environment in specific processes, such as metal oxidation or catalyst activation. Application scenarios: preparation of metal oxide films, surface oxidation treatment of catalysts, etc. Caution: It should be mixed with other gases to avoid excessive oxidation. Carbon dioxide (CO ₂) Usage: As an oxidizing medium, it participates in carburizing or oxidation reactions. Application scenarios: nitrogen based atmosphere carburizing process, special material oxidation treatment, etc. 4. Mixed gas Nitrogen hydrogen mixture (N ₂+H ₂) Purpose: To protect heating while providing a reducing environment, prevent oxidation, and promote reduction reactions. Application scenarios: metal heat treatment, semiconductor material preparation, etc. Nitrogen hydrocarbon mixture (N ₂+hydrocarbons) Purpose: To protect heating or serve as a carburizing carrier gas, increasing the surface carbon content of materials. Application scenarios: Powder metallurgy sintering, metal surface carburizing treatment, etc. Nitrogen carbon hydrogen oxidation mixture (N ₂+hydrocarbons+CO ₂/H ₂ O/air) Purpose: To control carbon potential and optimize material properties in carburizing process. Application scenarios: high-precision gear manufacturing, carburizing treatment of mold steel, etc. Nitrogen methanol mixture (N ₂+CH ∝ OH) Purpose: To protect heating or serve as a carburizing carrier gas, providing a controllable carbon source. Application scenarios: Precision parts carburizing, synthesis of special materials, etc.