CN114540746A - Special vacuum rotary nitriding furnace for rare earth nitride - Google Patents

Special vacuum rotary nitriding furnace for rare earth nitride Download PDF

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CN114540746A
CN114540746A CN202111305043.7A CN202111305043A CN114540746A CN 114540746 A CN114540746 A CN 114540746A CN 202111305043 A CN202111305043 A CN 202111305043A CN 114540746 A CN114540746 A CN 114540746A
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nitriding
furnace body
furnace
rare earth
vacuum
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CN114540746B (en
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赵宇
沈定君
涂元浩
何馨怡
于京京
王栋
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Hangzhou Permanent Magnet Group Co ltd
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Hangzhou Permanent Magnet Group Co ltd
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    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C8/00—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
    • C23C8/06—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases
    • C23C8/08—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases only one element being applied
    • C23C8/24—Nitriding
    • C23C8/26—Nitriding of ferrous surfaces
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F41/00—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties
    • H01F41/02—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets
    • H01F41/0253—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets for manufacturing permanent magnets
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P20/00—Technologies relating to chemical industry
    • Y02P20/10—Process efficiency

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  • Chemical & Material Sciences (AREA)
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  • Chemical Kinetics & Catalysis (AREA)
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  • Mechanical Engineering (AREA)
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  • Organic Chemistry (AREA)
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Abstract

The invention relates to the technical field of powder processing, and discloses a vacuum rotary nitriding furnace special for rare earth nitride, which comprises a furnace body, a control unit, a nitrogen supply device, a vacuumizing device and a heating device, wherein the nitrogen supply device, the vacuumizing device and the heating device are connected with the furnace body; a rotary powder barrel is arranged in the furnace body; the furnace body sequentially comprises a metal shell layer, a cooling circulating water layer and a composite material inner layer from outside to inside; the composite material inner layer sequentially comprises a graphene coating, a resin glass fiber layer and a fluorine adhesive layer from inside to outside. The inner wall of the nitriding furnace has certain toughness, can bear enough gas pressure, ensures the nitriding diffusion rate and improves the nitriding pressure; the isotropy of the graphene can reduce nitriding temperature difference. In addition, in the vacuum-pumping and exhausting state, the inner wall is in a concave lens shape under the action of double negative pressure, so that the exhaust efficiency and quality can be improved. And under the heating, inflating and nitriding state, the concave lens shape plays a pascal principle, and the product is subjected to temperature equalization nitriding in all directions and angles. In addition, the structure can effectively save the consumption of nitrogen.

Description

Special vacuum rotary nitriding furnace for rare earth nitride
Technical Field
The invention relates to the technical field of powder processing, in particular to a vacuum rotary nitriding furnace special for rare earth nitride.
Background
With the rapid development of science and technology, especially in the fields of automobiles, aerospace and the like, under various extreme environmental conditions, more strict requirements are imposed on various materials. Permanent magnets are used as materials with the most important functions and are more and more widely applied in the fields of national economy and science and technology. In 1990, Coey et al prepared intermetallic compound R by gas-solid phase reaction2Fe17NxWherein Sm2Fe17NxAre attracting much attention. Magnetic property Sm2Fe17NxThe saturation magnetization of the magnetic material can reach 1.54T; sm2Fe17NxThe Curie temperature of (A) is 470 ℃; sm2Fe17NxThe anisotropy field of (2) reaches 14T; in terms of physicochemical properties, Sm2Fe17NxThe key performances of corrosion resistance, oxidation resistance, high temperature resistance and the like are excellent; in addition, in the aspect of price, samarium and iron raw materials have more resources and are cheap, wherein the samarium raw materials are surplus in capacity in China and have low raw material cost. To sum up, Sm was developed2Fe17NxThe magnet has wide market prospect and higher market value.
At present, samarium iron nitrogen magnetic materials have higher requirements on atmosphere in the preparation process, and nitriding pressure, temperature, oxygen content in nitriding environment and the like can directly influence the performance of the finally obtained product. The existing nitriding furnace generally adopts the traditional heat preservation material. For example, chinese patent application No. CN201711046274.4 discloses a nitriding furnace, which comprises a furnace body, wherein a base is arranged in the furnace body, a workpiece cathode is arranged on the base, a power supply is connected with a transformer, the transformer is connected with a positive ion generating device arranged in the furnace body, a vacuum pump is further arranged, the furnace body is vacuumized by the vacuum pump, a gas supply device for supplying nitrogen to the furnace body is further arranged, and a gas circulating device is further arranged in the furnace body. The gas supply device is also provided with a control device, the control device is connected with a power supply, a vacuum pump and a gas supplier, the control device is also connected with a memory, and the memory is connected with a display. The outer layer of the furnace body is provided with a heat-insulating layer. The drawbacks of the existing nitriding furnaces, including the above patents, are: the traditional heat insulation materials are generally adopted, and the temperature range may have great difference. In addition, the furnace body of the existing nitriding furnace is generally not specially designed, can not bear higher pressure, and has small contact area of raw materials with nitrogen and long nitriding time in the nitriding process, so that the nitriding efficiency is poor, the cost is increased, and resources are wasted.
Disclosure of Invention
In order to solve the technical problems, the invention provides the vacuum rotary nitriding furnace special for the rare earth nitride, and when the nitriding furnace works, the nitriding temperature difference of each part in the furnace body is small, the exhaust efficiency/quality is high, high pressure can be borne, the nitriding efficiency is higher, and the nitrogen consumption can be saved.
The specific technical scheme of the invention is as follows: a vacuum rotary nitriding furnace special for rare earth nitride comprises a furnace body, a control unit, a nitrogen supply device, a vacuumizing device and a heating device, wherein the nitrogen supply device, the vacuumizing device and the heating device are connected with the furnace body. Wherein the control unit is used for controlling the operation of the nitriding furnace; a rotary powder barrel is arranged in the furnace body. The furnace body sequentially comprises a metal shell layer, a cooling circulating water layer and a composite material inner layer from outside to inside; the composite material inner layer sequentially comprises a graphene coating, a resin glass fiber layer and a fluorine adhesive layer from inside to outside.
The specific operation process of the nitriding furnace comprises the following steps: the method comprises the following steps: the furnace body is opened, the rotation function of the rotary powder barrel is started, the rotation direction and the rotation speed are set, magnetic powder is put into the rotary powder barrel, the furnace body is closed, and a program is started through the control unit. Step two: and starting the vacuumizing device to vacuumize the interior of the furnace body. Step three: and closing the vacuumizing device, starting the nitrogen supply device, and automatically executing a timing inflation and deflation process when the air pressure reaches a preset air pressure according to the set inflation (nitrogen) flow and time. Step four: and after the preset air pressure is reached, starting the heating device, setting the heating temperature and the heating time, operating the heating program, and performing nitriding treatment. Step five: and after nitriding is finished and cooling is carried out, air is released, the furnace body is opened, the rotating powder barrel is controlled to rotate reversely, and discharging is carried out.
The nitriding furnace has the advantages that: the inner and outer walls of the existing common nitriding furnace are all made of steel, and the middle part is a water-passing layer. The inner wall (namely the inner layer) of the nitriding furnace adopts composite materials, and the inner side from the outer side is respectively as follows: fluorine glue, resin glass fiber and a graphene coating. Wherein: the fluorine glue is used for sealing the water jacket and insulating the heat of the resin glass fiber, especially can resist deformation and provide certain toughness, can bear enough gas pressure in the cavity, ensure the nitriding diffusion rate and improve the nitriding pressure; the isotropy of the graphene can realize better uniform heat transfer, and for the traditional vacuum nitriding equipment, the lower the temperature is, the worse the temperature uniformity is, the temperature uniformity of the nitriding furnace with the highest temperature of 600 ℃ is +/-10 ℃, and the temperature uniformity of the nitriding furnace can reach +/-2 ℃ by adopting the graphene. Most importantly, because the material of the inner wall of the nitriding furnace has toughness, the inner wall can be in the shape of a concave lens under the double negative pressure action of a vacuum pump and a water jacket water pump in a vacuum pumping and exhausting state, and the exhaust efficiency and quality can be improved. And under the heating, inflating and nitriding state, the concave lens shape of the inner wall plays a pascal principle, and the product is subjected to temperature equalization nitriding in all directions and angles, which cannot be compared with the traditional nitriding furnace. And in terms of energy conservation, the nitriding pressure of an inflation valve of a common nitriding furnace is 0.2MPa, the water jacket pressure of a water pump is 0.3MPa, and the actual internal pressure of equipment is 0.2 MPa. On the premise of the same basic size of the furnace body, water pump, vacuum pump and gas charging quantity, the actual internal pressure of the equipment is 0.3MPa, so that nitrogen can be greatly saved, and the gas consumption is 2/3 of common equipment.
Preferably, the minimum withstand pressure of the inner layer of the composite material is not less than 0.4 MPa.
Preferably, the furnace body comprises a furnace cylinder, and a front furnace door and a rear furnace door which are positioned at two ends of the furnace cylinder; a plurality of water inlets and water return ports are distributed on each part of the furnace body. And an observation window is arranged on the forehearth door.
Preferably, the rotary powder barrel comprises a spiral barrel, a rotary driving mechanism and a plurality of rolling bearings; the spiral charging barrel is fixedly connected with and driven by the rotary driving mechanism fixed on the furnace body; the rolling bearing is fixed in the furnace body and positioned below the spiral charging barrel for supporting the spiral charging barrel.
Preferably, the rotary driving mechanism comprises a servo motor fixed on the rear oven door, the rated power of the servo motor is 1.2KW, the rated torque is 6N.M, the rated rotating speed is 2000r/min, and the servo motor is provided with a speed reducer in a ratio of 1: 100, so that the rotating speed of the powder groove reaches 2-4 r/min.
Preferably, the spiral charging barrel comprises a barrel body and a spiral blade axially arranged in the barrel body; one end of the cylinder body is provided with a powder inlet and a powder outlet. The helical blades are designed to achieve feeding and discharging in different directions of rotation.
The spiral charging barrel with the unique design is internally provided with spiral blades. The feeding is carried out when the rotating shaft rotates forwards, and the discharging is carried out when the rotating shaft rotates backwards. And the spiral structure can disturb nitrogen gas flow, so that the gas is more uniform, and the nitriding efficiency is improved.
Preferably, the heating device comprises a plurality of heating rods which are fixed in the furnace body and uniformly surround the outer side of the spiral material barrel.
Preferably, the heating rod is a U-shaped alumina chromium heating rod, the maximum temperature is 650 ℃, and the maximum heating power is 75 KVA.
Preferably, the nitrogen supply device comprises a main gas pipe and a plurality of branch gas pipes communicated with the furnace body; the branch gas pipe is connected with one end of the main gas pipe in a parallel mode; the main gas pipe is connected with a gas inlet valve, a flow meter, a safety valve, a gas exhaust valve, an angle control valve, an ionization gauge and a resistance gauge, and the other end of the main gas pipe is connected with a butterfly valve.
Preferably, the branch gas pipes comprise a plurality of primary branch gas pipes which are connected in parallel and communicated with the main gas pipe, and a plurality of secondary branch gas pipes which are connected in parallel and communicated with the primary branch gas pipes and the furnace body; the secondary bronchus is in a U-shaped tubular shape. And the plurality of secondary branch gas pipes are uniformly connected at different positions of the bottom of the furnace body.
The invention is designed with multi-stage gas pipelines, especially with the two-stage branch gas pipes uniformly distributed at the bottom of the furnace body, which can realize porous uniform gas extraction, faster and more uniform gas extraction, and the gas extraction is in viscous flow-molecular flow (transition flow) and molecularThe efficiency of the flow is greatly improved by the advantages of multiple pumping time. From atmospheric pressure to 5X 10-2Pa, the same pump set pumping time was reduced from 60 minutes to 30 minutes. The air exhaust, inflation, exhaust and product support share the pipeline and the supporting piece, so that the equipment cost can be reduced, and the production efficiency and quality of products can be improved.
Preferably, the number of the primary branch gas pipes is 2, the primary branch gas pipes are connected in an I shape through connecting pipes, and the connecting pipes are communicated with the main gas pipe; the number of the secondary bronchus is six, and every three secondary bronchus is communicated with one primary bronchus in a parallel and parallel mode.
Preferably, the vacuumizing device comprises a roots pump and a mechanical pump which are connected in series, and the roots pump is communicated with the main gas pipe. The maximum vacuum degree of the vacuum extractor is 3.5 multiplied by 10-2Pa。
Preferably, a support is arranged in the furnace body, and the support is arranged around the outer sides of the rotary powder barrel and the heating device.
Compared with the prior art, the invention has the beneficial effects that:
(1) the inner wall of the nitriding furnace is made of composite materials, so that certain toughness can be provided, the cavity can bear enough gas pressure, the nitriding diffusion rate is ensured, and the nitriding pressure is improved; the isotropy of the graphene can reduce nitriding temperature difference. Most importantly, in the vacuum-pumping and air-exhausting state, the inner wall can be in the shape of a concave lens under the action of double negative pressure, so that the air-exhausting efficiency and quality can be improved. And under the heating, inflating and nitriding state, the concave lens shape of the inner wall plays a pascal principle, and the product is subjected to temperature equalization nitriding in all directions and angles. Moreover, the structure can effectively save the consumption of nitrogen.
(2) The invention designs a unique spiral charging barrel, and the spiral blade is arranged in the special spiral charging barrel, so that forward and reverse rotation feeding and discharging can be realized; and the spiral structure can disturb nitrogen gas flow, so that the gas is more uniform, and the nitriding efficiency is improved.
(3) The invention is designed with multi-stage gas pipelines, especially with the two-stage branch gas pipes uniformly distributed at the bottom of the furnace body, which can realize porous uniform gas extraction, faster and more uniform gas extraction, and has advantages of multiple gas extraction time effects in viscous flow-molecular flow (transition flow) and molecular flowThe rate is greatly improved. From atmospheric pressure to 5X 10-2Pa, the same pump set pumping time was reduced from 60 minutes to 30 minutes. The air exhaust, inflation, exhaust and product support share the pipeline and the supporting piece, so that the equipment cost can be reduced, and the production efficiency and quality of products can be improved.
Drawings
FIG. 1 is a schematic view showing an appearance of a nitriding furnace according to the present invention;
FIG. 2 is a schematic front view of a nitriding furnace according to the present invention;
FIG. 3 is a schematic side view of a nitriding furnace according to the present invention;
FIG. 4 is a schematic plan view of a nitriding furnace according to the present invention;
FIG. 5 is a schematic plan view of the nitriding furnace body of the present invention;
FIG. 6 is a schematic view of a nitriding furnace of the present invention constituted by a rotary powder cartridge, a nitrogen supplying means and a heating means;
FIG. 7 is a schematic top view of a nitriding furnace according to the present invention, comprising a rotary powder cartridge, a nitrogen supplying means and a heating means;
FIG. 8 is a schematic side view of a nitriding furnace according to the present invention, comprising a rotary powder cartridge, a nitrogen supplying means and a heating means;
FIG. 9 is a schematic side view of a nitriding furnace according to the present invention, comprising a rotary powder cartridge, a nitrogen supplying means and a heating means;
FIG. 10 is a schematic sectional view of a rotary powder cartridge in a nitriding furnace according to the present invention;
FIG. 11 is a schematic view showing a structure of a spiral vane cartridge in a nitriding furnace according to the present invention;
FIG. 12 is a schematic side view of a rotary powder cartridge in a nitriding furnace according to the present invention;
the reference signs are: the furnace body 1, the control unit 2, the rotary powder barrel 101, the metal shell layer 102, the cooling circulating water layer 103, the composite material inner layer 104, the furnace barrel 105, the front furnace door 106, the rear furnace door 107, the water inlet 108, the water return opening 109, the observation window 110, the bracket 111, the heating rod 301, the main gas pipe 401, the primary gas pipe 402, the secondary gas pipe 403, the gas inlet valve 404, the flow meter 405, the safety valve 406, the exhaust valve 407, the angle control valve 408, the ionization gauge 409, the butterfly valve 410, the resistance gauge 411, the roots pump 501, the mechanical pump 502, the barrel 1011, the rolling bearing 1012, the servo motor 1013 and the spiral blade 1014. Powder inlet and outlet 1015.
Detailed Description
The present invention will be further described with reference to the following examples.
General examples
As shown in fig. 1-4, a vacuum rotary nitriding furnace special for rare earth nitrides comprises a furnace body 1, a control unit 2, and a nitrogen supply device, a vacuum pumping device and a heating device which are connected with the furnace body. Specifically, the method comprises the following steps:
the control unit is used for controlling the operation of the whole nitriding furnace, including rotation, heating, vacuum pumping, nitrogen pumping/filling and the like, and can be a control unit commonly used in the prior art.
As shown in fig. 5, the furnace body comprises a furnace barrel 105, and a front furnace door 106 and a rear furnace door 107 which are positioned at two ends of the furnace barrel; a plurality of water inlets 108 and water return ports 109 for cooling are uniformly distributed on each part of the furnace body; the front oven door is also provided with an observation window 110. The furnace body sequentially comprises a metal shell layer 102, a cooling circulating water layer 103 and a composite material inner layer 104 from outside to inside; the composite material inner layer sequentially comprises a graphene coating, a resin glass fiber layer and a fluorine adhesive layer from inside to outside, and the minimum bearing pressure of the composite material inner layer is not less than 0.4 MPa. As shown in fig. 6, a rotary powder cartridge 101 and a holder 111 are provided in the furnace body, and the holder is provided around the outer side of the rotary powder cartridge and the heating device. As shown in fig. 1, 9, the rotary powder cartridge includes a screw cartridge, a rotary drive mechanism, and a plurality of rolling bearings 1012. As shown in fig. 10, the helical cylinder further comprises a cylinder body 1011 and a helical blade 1014 axially arranged in the cylinder body; one end of the cylinder is provided with a powder inlet and outlet 1015. As shown in fig. 11, the spiral blades are designed to achieve feeding and discharging in different directions of rotation. As shown in fig. 1, the spiral charging barrel is fixedly connected with and driven by a rotary driving mechanism fixed on the furnace body; as shown in fig. 9, the rolling bearing is fixed in the furnace body and located below the screw barrel for supporting the screw barrel. The rotary driving mechanism comprises a servo motor 1013 fixed on the rear oven door, the rated power of the servo motor is 1.2KW, the rated torque is 6N.M, the rated rotation speed is 2000r/min, the servo motor is provided with a speed reducer with the ratio of 1: 100, so that the rotation speed of the powder groove reaches 2-4 r/min.
As shown in fig. 7 to 8, the heating device includes a plurality of heating rods 301 fixed in the furnace body and uniformly surrounding the outside of the screw barrel. The heating rod is preferably a U-shaped alumina chromium heating rod, the maximum temperature is 650 ℃, and the maximum heating power is 75 KVA.
As shown in fig. 6-9, the nitrogen supply device comprises a main gas pipe 401 and a plurality of branch gas pipes communicated with the furnace body; the branch gas pipe is connected with one end of the main gas pipe in a parallel mode; an air inlet valve 404, a flow meter 405, a safety valve 406, an exhaust valve 407, an angle control valve 408, an ionization gauge 409 and a resistance gauge 411 are connected to the main air pipe, and the other end of the main air pipe is connected with a butterfly valve 410. Preferably, the branch gas pipes comprise a plurality of primary branch gas pipes 402 which are connected in parallel and communicated with the main gas pipe, and a plurality of secondary branch gas pipes 403 which are connected in parallel and communicated with the primary branch gas pipes and the furnace body; the secondary bronchus is in a U-shaped tubular shape. And all the secondary branch gas pipes are uniformly distributed at different positions of the bottom of the furnace body. Most preferably, the number of the primary branch air pipes is 2, the primary branch air pipes are connected in an I shape through connecting pipes, and the connecting pipes are communicated with a main air pipe; the number of the secondary bronchus is six, and every three secondary bronchus is communicated with one primary bronchus in a parallel and parallel mode.
As shown in fig. 1, 2 and 4, the vacuum-pumping device comprises a roots pump 501 and a mechanical pump 502 which are connected in series, wherein the roots pump is communicated with a main gas pipe. The maximum vacuum degree of the vacuum extractor is 3.5 multiplied by 10-2Pa。
Example 1
As shown in fig. 1-4, a vacuum rotary nitriding furnace special for rare earth nitrides comprises a furnace body 1, a control unit 2, and a nitrogen supply device, a vacuum pumping device and a heating device which are connected with the furnace body. Specifically, the method comprises the following steps:
the control unit is used for controlling the operation of the whole nitriding furnace, including rotating, heating, vacuumizing, nitrogen pumping/filling and other operations, and can be a control unit commonly used in the prior art.
As shown in fig. 5, the furnace body comprises a furnace barrel 105, and a front furnace door 106 and a rear furnace door 107 which are positioned at two ends of the furnace barrel; four water inlets 108 and water return ports 109 for cooling are respectively and uniformly distributed on two sides of the furnace body; the front oven door is also provided with an observation window 110. The furnace body sequentially comprises a metal shell layer 102, a cooling circulating water layer 103 and a composite material inner layer 104 from outside to inside; the composite material inner layer sequentially comprises a graphene coating, a resin glass fiber layer and a fluorine adhesive layer from inside to outside, and the minimum bearing pressure of the composite material inner layer is not less than 0.4 MPa. As shown in fig. 6, a rotary powder cartridge 101 and a holder 111 are provided in the furnace body, and the holder is enclosed outside the rotary powder cartridge and the heating device. As shown in fig. 1, 9, the rotary powder cartridge includes a screw cartridge, a rotary drive mechanism, and two sets (two in each set) of rolling bearings 1012. As shown in fig. 10, the helical cylinder further comprises a cylinder body 1011 and a helical blade 1014 axially arranged in the cylinder body; one end of the cylinder is provided with a powder inlet and outlet 1015. As shown in fig. 11, the spiral blades are designed to achieve feeding and discharging in different directions of rotation. As shown in fig. 1, the spiral charging barrel is fixedly connected with and driven by a rotary driving mechanism fixed on the furnace body; as shown in fig. 9, two sets of rolling bearings are fixed in the furnace body and located below the two ends of the screw barrel for supporting the screw barrel. The rotary driving mechanism comprises a servo motor 1013 fixed on the rear oven door, the rated power of the servo motor is 1.2KW, the rated torque is 6N.M, the rated rotation speed is 2000r/min, the servo motor is provided with a speed reducer with the ratio of 1: 100, so that the rotation speed of the powder groove reaches 2-4 r/min.
As shown in fig. 7-8, the heating device comprises four heating rods 301 (U-shaped alumina chrome heating rod with a maximum temperature of 650 ℃ and a maximum heating power of 75KVA) fixed in the furnace body and uniformly surrounding the outside of the screw cylinder.
As shown in fig. 6-9, the nitrogen supply device comprises a main gas pipe 401 and a branch gas pipe communicated with the furnace body; the branch gas pipe is connected with one end of the main gas pipe in a parallel mode; the bronchus includes two one-level bronchus 402 (be the I shape through the connecting pipe and connect, connecting pipe and total trachea intercommunication) that connect in parallel and communicate with the total trachea to and six parallelly connected and with one-level bronchus, furnace body intercommunication's second grade bronchus 403 (be U type tubulose), and every three second grade bronchus with a one-level bronchus intercommunication in parallel. And all the secondary branch gas pipes are uniformly distributed at different positions of the bottom of the furnace body. An air inlet valve 404, a flow meter 405, a safety valve 406, an exhaust valve 407, an angle control valve 408, an ionization gauge 409 and a resistance gauge 411 are connected to the main air pipe, and the other end of the main air pipe is connected with a butterfly valve 410.
As shown in fig. 1, 2 and 4, the vacuum-pumping device comprises a roots pump 501 and a mechanical pump 502 which are connected in series, wherein the roots pump is communicated with a main gas pipe. The maximum vacuum degree of the vacuum extractor is 3.5 multiplied by 10-2Pa。
Application example 1
The nitriding operation was carried out using the nitriding furnace of example 1.
(1) Opening a front furnace door of the vacuum rotary nitriding furnace, setting the rotation direction of the rotary powder barrel to be positive rotation, and setting the rotating speed to be 1 r/mn. Samarium iron nitrogen powder (Sm)2Fe17N3Average particle size of 5 microns) is placed in a rotary powder cylinder, the feeding mass is 50kg, then a front furnace door is closed, and the rotary powder cylinder is controlled to rotate forward and backward alternately; the forward rotation time is 6min, the reverse rotation time is 5min, and the total rotation time is 11 min; the rotating speed is 1 r/min.
(2) Firstly, locking the front furnace door of the furnace body, opening the mechanical pump and the Roots pump to carry out vacuum pumping treatment until the vacuum degree reaches 5 multiplied by 10-2Pa。
(3) The roots pump and the mechanical pump are closed, and the nitrogen supply device is started: opening an air inlet valve, observing a flowmeter, closing the air inlet valve when the air pressure reaches 0.25MPa, and setting an air charging and discharging program to perform alternating nitrogen charging and discharging treatment, wherein the nitrogen charging flow is 20L/min: firstly, filling nitrogen and naturally exhausting, wherein the filling flow is 20L/min, and the exhausting flow is 10L/min; then, filling nitrogen and exhausting at constant pressure, wherein the filling flow is 20L/min of the exhaust flow; the two processes are alternately carried out every 2h, and a heating device is started to carry out heating and nitriding treatment on the furnace body; the heating temperature is 500 ℃, and the heating time is 12 h.
(4) And after nitriding is finished, cooling and deflating are carried out, a furnace door in front of the furnace body is opened, and the rotary powder barrel is controlled to rotate reversely to discharge.
The properties of the product obtained above were as follows:
product of Remanence (kGs) Intrinsic coercive force (kOe) Maximum magnetic energy product (MGOe)
Sm2Fe17N3 6.58 6.91 9.64
The raw materials and equipment used in the invention are common raw materials and equipment in the field if not specified; the methods used in the present invention are conventional in the art unless otherwise specified.
The above description is only a preferred embodiment of the present invention, and is not intended to limit the present invention, and all simple modifications, alterations and equivalents of the above embodiments according to the technical spirit of the present invention are still within the protection scope of the technical solution of the present invention.

Claims (10)

1. A vacuum rotary nitriding furnace special for rare earth nitride comprises a furnace body (1), a control unit (2), a nitrogen supply device, a vacuumizing device and a heating device, wherein the nitrogen supply device, the vacuumizing device and the heating device are connected with the furnace body; the control unit is used for controlling the operation of the nitriding furnace; a rotary powder barrel (101) is arranged in the furnace body; the method is characterized in that: the furnace body sequentially comprises a metal shell layer (102), a cooling circulating water layer (103) and a composite material inner layer (104) from outside to inside; the composite material inner layer sequentially comprises a graphene coating, a resin glass fiber layer and a fluorine adhesive layer from inside to outside.
2. The vacuum rotational nitriding furnace special for rare earth nitride according to claim 1, characterized in that: the minimum bearing pressure of the inner layer of the composite material is not less than 0.4 MPa.
3. The vacuum rotational nitriding furnace special for rare earth nitride according to claim 1, characterized in that: the rotary powder barrel comprises a spiral barrel, a rotary driving mechanism and a plurality of rolling bearings (1012); the spiral charging barrel is fixedly connected with and driven by the rotary driving mechanism fixed on the furnace body; the rolling bearing is fixed in the furnace body and positioned below the spiral charging barrel for supporting the spiral charging barrel.
4. The vacuum rotational nitriding furnace special for rare earth nitride according to claim 3, characterized in that: the spiral barrel comprises a barrel body (1011) and a spiral blade (1014) axially arranged in the barrel body; one end of the cylinder body is provided with a powder inlet and outlet (1015).
5. The vacuum rotary nitriding furnace special for rare earth nitride according to claim 1, 3 or 4, characterized in that: the heating device comprises a plurality of heating rods (301) which are fixed in the furnace body and uniformly surround the outer side of the spiral charging barrel.
6. The vacuum rotational nitriding furnace special for rare earth nitride according to claim 1, characterized in that: the nitrogen supply device comprises a main gas pipe (401) and a plurality of branch gas pipes communicated with the furnace body; the branch gas pipe is connected with one end of the main gas pipe in a parallel mode; the main gas pipe is connected with an air inlet valve (404), a flowmeter (405), a safety valve (406), an exhaust valve (407), an angle control valve (408), an ionization gauge (409) and a resistance gauge (411), and the other end of the main gas pipe is connected with a butterfly valve (410).
7. The vacuum rotary nitriding furnace special for rare earth nitride according to claim 6, characterized in that: the branch gas pipes comprise a plurality of primary branch gas pipes (402) which are connected in parallel and are communicated with the main gas pipe, and a plurality of secondary branch gas pipes (403) which are connected in parallel and are communicated with the primary branch gas pipes and the furnace body; the secondary bronchus is in a U-shaped tubular shape.
8. The vacuum rotary nitriding furnace special for rare earth nitride according to claim 7, characterized in that: the number of the primary branch gas pipes is 2, the primary branch gas pipes are connected in an I shape through connecting pipes, and the connecting pipes are communicated with a main gas pipe; the number of the secondary bronchus is six, and every three secondary bronchus is communicated with one primary bronchus in a parallel and parallel mode.
9. The vacuum rotary nitriding furnace special for rare earth nitride according to claim 6, 7 or 8, characterized in that: the vacuum pumping device comprises a roots pump (501) and a mechanical pump (502) which are connected in series, and the roots pump is communicated with a main gas pipe.
10. The vacuum rotational nitriding furnace special for rare earth nitride according to claim 1, characterized in that: a support (111) is arranged in the furnace body, and the support is arranged around the outer sides of the rotary powder barrel and the heating device.
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