What is the difference between a vacuum furnace and an atmosphere furnace?

There are significant differences between vacuum furnaces and atmosphere furnaces in multiple aspects. The following is a detailed explanation of the differences between the two:

1、 Working principle
Vacuum furnace:
A vacuum furnace is a device that uses a vacuum system (composed of carefully assembled components such as vacuum pumps, vacuum measuring devices, and vacuum valves) to discharge some of the material inside the furnace cavity, so that the pressure inside the furnace cavity is less than a standard atmospheric pressure, thereby achieving a vacuum state in the furnace cavity.
The products in the vacuum furnace are processed by surrounding a vacuum atmosphere. Under vacuum conditions, there is no air or other gas, which can prevent oxidation and dissipate heat from the products through convection, thereby eliminating pollution sources.
Atmosphere furnace:
The atmosphere furnace, on the other hand, provides atmosphere protection without vacuuming under normal conditions, allowing the atmosphere to pass through to meet the needs of customers for product processing.
It achieves specific chemical reactions or physical changes by precisely controlling the gas composition, flow rate, and temperature inside the furnace.

2、 Structural composition
Vacuum furnace:
A vacuum furnace is a circular structure composed of a furnace body, furnace door, heating element, insulation element, control, measurement, power supply, and vacuum system.
The vacuum system is composed of a vacuum pump, vacuum measuring device, vacuum valve, etc., which can achieve a high vacuum degree, and the furnace vacuum degree can reach 133 × (10-2-10-4) Pa.
Atmosphere furnace:
The atmosphere furnace consists of a furnace body, an inner liner moving frame, temperature control, a resistance wire heating system, and a display system. The furnace door has a cooling water system, and there are several inlet and outlet valves on the furnace body, allowing it to air in and out at the same time.
The atmosphere furnace is an improved version of the ordinary muffle furnace. The box is fully welded, and the furnace body is sealed with silicone rubber, usually in a square structure.

3、 Processing characteristics
Vacuum furnace:
The vacuum furnace eliminates oxidation and decarburization on the surface of the workpiece during the heating process, ensuring that there is no deterioration layer on its surface.
The vacuum furnace adopts zone heating, and the temperature in the heating area remains consistent, making the workpiece smooth and clean.
Atmosphere furnace:
The atmosphere furnace selects the appropriate atmosphere according to different materials, and passes gas into the furnace for sintering, which is beneficial for improving the densification degree of the workpiece and enhancing its performance and quality.

4、 Application scope
Vacuum furnace:
Mainly used in vacuum brazing work such as stainless steel heat exchangers, stainless steel insulation cups, and oil coolers; Metal brazing of non-ferrous metals, titanium alloys, high-temperature alloys, and hard alloys; Vacuum tempering treatment of materials such as tooling steel, bearing steel, and high-speed steel; Vacuum brazing of aluminum products such as aluminum alloy heat exchangers.
Atmosphere furnace:
Suitable for industrial and mining laboratories, laboratories of various universities, and other places, providing data for chemical analysis and material determination, measuring high-temperature sintering and dissolution of metals and ceramics under specified conditions.
Atmosphere furnaces are mainly used in industries such as metallurgy, heat treatment, grinding tools, abrasives, and glass.

In summary, there are significant differences between vacuum furnaces and atmosphere furnaces in terms of working principle, structural composition, processing characteristics, and application scope. The choice of equipment depends on specific processing requirements and conditions for decision-making.