The RHN pre - evacuated gas nitriding furnace is a type of equipment used for the nitriding treatment of metal materials. It has the following characteristics and advantages:

Structural Features

Compact Structure: It adopts a single - door design for loading and unloading materials, which is compact and saves floor space.

High - Quality Furnace Lining: The furnace body is air - tight and consists of a vacuum - pumping system, a heating system, and a rapid - cooling system. The furnace lining is made of super - light - weight, high - strength energy - saving refractory micro - bead bricks, with high - purity ceramic fiber sandwiched on the outer layer and expanded vermiculite powder filled in the middle, which has good heat - preservation performance.

Horizontal Circular Muffle Tank: The heating chamber is equipped with a heat - resistant steel muffle tank. The circular muffle tank is a welded assembly of heat - resistant steel plates. Its flange is fixed to the furnace shell flange. The special structural design of the furnace ensures that the muffle tank can freely expand backward when heated, avoiding deformation due to stress.

An RHN pre-evacuated gas nitriding furnace is a specialized industrial Heat treatment furnace used for nitriding—a thermochemical process that introduces nitrogen into the surface of a metal (typically steel) to improve hardness, wear resistance, and fatigue life.

Here’s a breakdown of the key terms:

1. RHN Furnace

"RHN" typically refers to a specific model or series of nitriding furnaces—often manufactured by certain companies. These furnaces are designed for controlled gas nitriding and may include advanced process control systems. It can also stand for "Retort-type Horizontal Nitriding" depending on context, indicating a horizontal retort furnace structure.

2. Pre-Evacuated

"Pre-evacuated" means that before the nitriding gas is introduced, the furnace chamber is evacuated (vacuumed) to remove air and impurities. This helps:

Eliminate oxygen and moisture.

Ensure a pure nitriding atmosphere.

Improve process repeatability and uniformity.

3. Gas Nitriding

Gas nitriding involves:

Heating the steel to 500–550°C in an atmosphere of ammonia (NH₃) or a mix of gases.

The ammonia dissociates on the metal surface, releasing nitrogen which diffuses into the metal.

Results in a hard nitride layer without quenching (i.e., less distortion).

Advantages of an RHN Pre-Evacuated Gas Nitriding Furnace

High control over case depth and nitrogen potential.

Clean and energy-efficient process.

Minimal distortion due to low processing temperatures.

Improved surface hardness and corrosion resistance.

Efficient Gas Circulation: There is an atmosphere - circulation fan made of heat - resistant alloy installed in the muffle tank. The high - speed circulation fan draws out the atmosphere in the furnace guide cylinder backward, then moves forward along the heating chamber outside the guide cylinder to the front furnace door, and returns to the furnace chamber. The furnace gas is heated when passing through the heating chamber, which ensures the uniformity of the temperature and atmosphere in the furnace.

Complete Exhaust Gas Treatment: An exhaust gas combustion system is installed at the rear of the furnace, including an ignition burner, a flame monitor, an annular burner, and a control valve, which ensures that the exhaust gas after combustion and decomposition meets the relevant emission standards.

Process Advantages

Accurate Atmosphere Control: It is equipped with a German - imported hydrogen probe and a nitrogen potential control system, and an American - imported mass flow meter is installed on the atmosphere panel. The hydrogen probe feeds back the measured atmosphere conditions in the furnace to the nitrogen potential control system, and the system calculates the gas intake and directly controls the mass flow meter. This can not only ensure the stability of the atmosphere in the furnace but also accurately control it.

Fast Vacuum - Pumping: The vacuum system can quickly and cleanly remove the air in the furnace, shorten the gas replacement time, and save the protective gas. During the nitriding process, if it is necessary to change the atmosphere composition in the furnace, the method of pumping vacuum and then inputting the required gas can be used to quickly and accurately establish a new process atmosphere.

Rapid Cooling Capability: It is equipped with an external cooling system and an internal cooling system. The external cooling system cools the furnace tank by blowing air into the heating chamber through a fan after the nitriding process is completed, and the hot air is discharged through the discharge valve at the upper part of the furnace body. The internal cooling system is a fully vacuum - sealed installation. Through a special fan, the protective atmosphere in the furnace is blown into the water - cooled heat exchanger. The high - temperature gas is cooled by the cooling water and then returned to the muffle tank in the furnace to directly cool the nitrided workpieces, which can significantly improve the cooling speed of the workpieces and increase the production efficiency.

In summary, the RHN pre - evacuated gas nitriding furnace has the advantages of precise process control, high production efficiency, and good product quality, and is widely used in the heat treatment of metal materials in the machinery manufacturing, automotive, aerospace, and other industries.