Method for Manufacturing a Multi-Purpose Furnace for Pressurized Gas Nitriding
The multi-purpose furnace for pressurized gas nitriding comprises a furnace body. Said furnace body includes a pressure vessel, heating elements, a heating nitriding chamber situated within the pressure vessel, a cooling system located on the exterior of the pressure vessel. A refractory thermal insulation layer is provided on the inner wall of the pressure vessel; the walls of the heating nitriding chamber are formed by this refractory thermal insulation layer, the heating elements are mounted upon said insulation layer. In the prior art, to enhance properties such as the hardness, wear resistance, corrosion resistance of the surface layers of metal workpieces, a chemical heat treatment process known as nitriding is employed to diffuse nitrogen atoms into the surface layers of steel. There are various methods of nitriding; gas nitriding ion nitriding are two of the most frequently utilized techniques. Gas nitriding is currently the most widely adopted method in industrial production, offering stable process performance excellent nitriding results. The specific process is as follows: metal workpieces are placed inside a sealed, heat-resistant steel vessel; a flow of nitrogen gas ammonia gas is introduced; the vessel is heated held at temperature for an extended period. During this time, the nitrogen ammonia gas undergoes thermal decomposition to generate active nitrogen atoms, which are continuously adsorbed onto the surface of the metal workpieces subsequently diffuse into the surface layers, thereby altering the chemical composition microstructure of the surface yielding superior surface properties.
The sealed steel vessel is typically fabricated heat-resistant steel. However, at temperatures of approximately 560°C above, the mechanical properties of heat-resistant steel deteriorate sharply. Consequently, at such temperatures, the internal pressure of the nitrogen ammonia gas within the heat-resistant steel vessel cannot be excessively high—specifically, it must exceed 0.01 MPa (0.1 kg/cm²). Since the rate quality of the nitriding process are directly correlated with the internal pressure of the nitrogen ammonia gas within the heat-resistant steel vessel, the chemical heat treatment process for nitriding becomes extremely time-consuming (typically requiring 70–80 hours), thereby severely undermining the economic efficiency of the enterprise. In light of this, the objective of the present utility model is to provide a multi-purpose furnace for pressurized gas nitriding capable of significantly reducing the duration of the chemical heat treatment process. This aims to resolve the technical challenge posed by the protracted nitriding cycles inherent in the prior art, thereby enhancing the efficiency of nitriding operations within heat treatment enterprises. To address the aforementioned problems, the present utility model adopts the following technical solution: a multi-purpose furnace for pressurized gas nitriding, comprising a furnace body; the furnace body includes a pressure-bearing vessel, heating elements, a heating nitriding chamber situated within the pressure-bearing vessel, a cooling system situated on the exterior of the pressure-bearing vessel; a refractory thermal insulation layer is provided on the inner wall of the pressure-bearing vessel, the walls of the heating nitriding chamber consist of said refractory thermal insulation layer, the heating elements are mounted upon said refractory thermal insulation layer.
In the aforementioned multi-purpose furnace for pressurized gas nitriding, the cooling system comprises a circulating water jacket encasing the exterior of the pressure-bearing vessel; a cavity exists between the inner wall of the circulating water jacket the outer wall of the pressure-bearing vessel, this cavity contains circulating cooling water; the circulating water jacket is provided with a cooling water inlet a cooling water outlet, both of which are in fluid communication with said cavity.
In the aforementioned multi-purpose furnace for pressurized gas nitriding, the thickness of the refractory thermal insulation layer is 5–15 centimeters.
In the aforementioned multi-purpose furnace for pressurized gas nitriding, the thickness of the refractory thermal insulation layer is 5–8 centimeters.
In the aforementioned multi-purpose furnace for pressurized gas nitriding, the multi-purpose furnace for pressurized gas nitriding is configured as either a vertical furnace a horizontal furnace.
In the aforementioned multi-purpose furnace for pressurized gas nitriding, the heating nitriding chamber is in fluid communication with a nitriding agent inlet an exhaust outlet, respectively, located on the furnace body.
In the aforementioned multi-purpose furnace for pressurized gas nitriding, a pressure gauge is installed on the exhaust outlet. This design enables a reduction in the processing time for the chemical heat treatment nitriding process, thereby resolving the technical problem—prevalent in the prior art—of the nitriding process being excessively time-consuming, enhancing the efficiency of nitriding operations within heat treatment enterprises; furthermore, the present utility model is also capable of being utilized for vacuum gas quenching, thereby achieving multi-purpose functionality, reducing equipment costs for heat treatment enterprises, improving the utilization rate of production equipment within such enterprises.