A method and device for preparing Ti-TiN core-shell powder

Abstract

The present invention relates to a method and device for preparing Ti-TiN core-shell powder. The method includes: in an atomization chamber, blowing a mixed gas onto the molten pool on the surface of an electrode rod material to perform primary refinement and primary coating and nitrogen increment treatment on droplets. The mixed gas includes argon and nitrogen, and the volume content of nitrogen does not exceed 10%; blowing high-temperature pure nitrogen onto the flying droplets to perform secondary refinement and secondary coating and nitrogen increment treatment, and the temperature of the high-temperature pure nitrogen is 1000-1500 °C; using an electrostatic separation device to separate the insufficiently coated powder and the sufficiently coated powder; performing a third coating and nitrogen increment treatment on the insufficiently coated powder to obtain Ti-TiN core-shell structure powder. The powder prepared by the present invention has a core-shell powder with a large thickness and a small fineness, a high yield, a uniform shell layer structure, a high powder sphericity, and a high preparation efficiency.

Description

Technical Field

[0001] The embodiments of the present invention relate to the technical field of atomization powder making, and particularly to a method and a device for preparing Ti-TiN core-shell powder. Background Art

[0002] Metallic titanium and titanium alloys have characteristics such as high melting point, high hardness, good chemical stability and biocompatibility, and are widely used in fields such as refractory materials, rocket boosters and clinical medicine. Metallic titanium (Ti) powder can form a new type of multifunctional ceramic material - titanium nitride (TiN) under the action of strengthening agents such as nitrogen. The metallic titanium powder is coated and modified on its surface through nitriding to form titanium-titanium nitride (Ti-TiN) core-shell structured powder. The titanium nitride shell can effectively improve the corrosion resistance, oxidation resistance, tensile strength and ductility of this core material of metallic titanium powder, and provides raw materials for additive manufacturing and powder metallurgy processes of titanium-based composite materials. The metallic titanium core-shell structured powder composed of titanium and titanium nitride has both metallic and non-metallic properties, and is mainly applied in fields such as aerospace, wave-absorbing materials, stealth materials, electrostatic shielding coatings and optoelectronic functional materials.

[0003] The preparation of traditional metallic core-shell powder mainly adopts mechanical coating and in-situ reaction coating. The mechanical coating process of titanium powder is to use a high-energy ball mill to make the metallic titanium powder collide strongly in a nitrogen or ammonia environment for nitriding. The main means of in-situ reaction coating of titanium powder are solid-phase method, liquid-phase method and gas-phase method. The solid-phase method requires solid-phase calcination of the powder in a nitrogen environment, which is a common industrial powder processing method. The liquid-phase method is to form a coating on the powder through a microemulsion containing a precursor or a gel formed by hydrolysis complexation reaction. The gas-phase method is to obtain core-shell powder by coating and depositing thermally evaporated active groups on the powder surface or by the interaction of a mixed gas with the surface of the substrate. The titanium core-shell powder prepared by the traditional powder coating method has disadvantages such as uneven coating, low yield, high cost, long cycle and low powder quality.

[0004] Therefore, it is necessary to improve one or more problems existing in the above related technical solutions.

[0005] It should be noted that this part aims to provide background or context for the technical solutions of the present invention stated in the claims. The description herein is not admitted to be prior art just because it is included in this part. Summary of the Invention

[0006] The purpose of the present invention is to provide a method and a device for preparing Ti-TiN core-shell powder, thereby at least to a certain extent solving one or more problems caused by the limitations and defects of the related technologies.

[0007] The present invention first provides a method for preparing Ti-TiN core-shell powder, the method comprising:

[0008] In an atomization chamber, a mixed gas is blown onto the molten pool on the surface of an electrode blank to perform primary refinement and primary coating and nitrogen increment treatment on the droplets formed after melting the electrode blank. The mixed gas includes argon and nitrogen, and the volume content of nitrogen does not exceed 10%;

[0009] High-temperature pure nitrogen is blown onto the droplets separated from the surface of the electrode blank to perform secondary refinement and secondary coating and nitrogen increment treatment on the droplets. The temperature of the high-temperature pure nitrogen is 1000-1500 °C;

[0010] An electrostatic separation device is used to separate the insufficiently coated powder and the sufficiently coated powder;

[0011] The insufficiently coated powder is returned to the atomization chamber for tertiary coating and nitrogen increment treatment, or the powder is subjected to tertiary coating and nitrogen increment treatment using a high-temperature TiN gas. The powder after the tertiary coating and nitrogen increment treatment and the sufficiently coated powder are cooled to obtain Ti-TiN core-shell structured powder.

[0012] In the present invention, the high-temperature pure nitrogen is blown onto the droplets flying out around the electrode blank, and the pressure of the high-temperature pure nitrogen is 1-10 MPa.

[0013] In the present invention, the nitrogen content in the atomization chamber is detected to ensure that the volume content of nitrogen in the mixed gas does not exceed 10%.

[0014] In the present invention, the electric field strength in the electrostatic separation device is 2-5 kV / cm.

[0015] The present invention also provides a method for preparing Ti-TiN core-shell powder, the method comprising:

[0016] In an atomization chamber, a mixed gas is blown onto the molten pool on the surface of an electrode blank to perform primary refinement and primary coating and nitrogen increment treatment on the droplets formed after melting the electrode blank. The mixed gas includes argon and nitrogen, and the volume content of nitrogen does not exceed 10%;

[0017] High-temperature pure nitrogen is blown onto the droplets separated from the surface of the electrode blank to perform secondary refinement and secondary coating and nitrogen increment treatment on the droplets. The temperature of the high-temperature pure nitrogen is 1000-1500 °C;

[0018] An electrostatic separation device is used to separate the insufficiently coated powder and the sufficiently coated powder;

[0019] The insufficiently coated powder is subjected to three times of coating and nitrogen increment treatment using a nitriding furnace, and the powder after the three times of coating and nitrogen increment treatment and the sufficiently coated powder are cooled to obtain Ti-TiN core-shell structured powder.

[0020] Secondly, the present invention provides a device for preparing Ti-TiN core-shell powder, and the device includes:

[0021] An atomization chamber, in which a first gas blowing device and a second gas blowing device are provided. The first gas blowing device is used to blow a mixed gas to the molten pool on the surface of the electrode rod, and the second gas blowing device is used to blow high-temperature pure nitrogen to the droplets flying out from the surface of the electrode rod.

[0022] An electrostatic separation device for separating the insufficiently coated powder and the sufficiently coated powder.

[0023] A three-time coating and nitrogen increment treatment device for performing three-time coating and nitrogen increment treatment on the insufficiently coated powder.

[0024] In the present invention, the three-time coating and nitrogen increment treatment device is a nitriding furnace.

[0025] In the present invention, the three-time coating and nitrogen increment treatment device includes:

[0026] A pressure vessel, in which a non-transferred arc type nitrogen-excited plasma torch is arranged. A pure titanium target is oppositely installed to the plasma torch. Under the action of the plasma torch, the pure titanium target is heated and evaporated and reacts with nitrogen to synthesize TiN high-temperature gas.

[0027] In the present invention, the device for preparing Ti-TiN core-shell powder further includes:

[0028] A cooling device for cooling the powder after being treated by the three-time coating and nitrogen increment treatment device.

[0029] The technical solution provided by the present invention may include the following beneficial effects:

[0030] In the present invention, through the above method and device, the droplets are firstly refined and subjected to the first coating and nitrogen increment treatment using a mixed gas of nitrogen and argon, secondly refined and subjected to the second coating and nitrogen increment treatment using high-temperature pure nitrogen, then the insufficiently coated powder is separated by electrostatic force, and then the three-time coating and nitrogen increment treatment is carried out, so that the prepared powder has a Ti-TiN core-shell powder with a large thickness and fineness, a high yield, a uniform shell layer structure, a high powder sphericity, and a high preparation efficiency. Description of the Drawings

[0031] The accompanying drawings herein are incorporated into and constitute a part of this specification, showing embodiments consistent with the present disclosure, and are used together with the specification to explain the principles of the present disclosure. Obviously, the accompanying drawings in the following description are only some embodiments of the present disclosure, and those of ordinary skill in the art can obtain other drawings based on these drawings without creative efforts.

[0032] Figure 1 A schematic flow chart showing a method for preparing Ti-TiN core-shell powder in an exemplary embodiment of the present invention;

[0033] Figure 2 A schematic structural diagram showing an apparatus for preparing Ti-TiN core-shell powder in an exemplary embodiment of the present invention;

[0034] Figure 3 A schematic structural diagram showing a system for preparing Ti-TiN core-shell powder in an exemplary embodiment of the present invention.

[0035] Reference numerals:

[0036] 10. Electrode rod stock; 20. Powder collection barrel; 30. Plasma rotating electrode;

[0037] 100. Atomization chamber; 101. First gas blowing device; 102. Second gas blowing device; 200. Electrostatic separation device; 300. Tertiary coating and nitrogen increment treatment device; 400. Cooling device. Detailed implementation manners

[0038] Example embodiments will now be described more fully with reference to the accompanying drawings. However, the example embodiments can be implemented in various forms and should not be construed as limited to the examples set forth herein; rather, these embodiments are provided so that this invention will be more complete and comprehensive, and will fully convey the concept of the example embodiments to those skilled in the art. The features, structures, or characteristics described can be combined in any suitable manner in one or more embodiments.

[0039] In addition, the accompanying drawings are only schematic illustrations of the embodiments of the present invention and are not necessarily drawn to scale. The same reference numerals in the drawings denote the same or similar parts, and thus repeated descriptions thereof will be omitted. Some of the block diagrams shown in the drawings are functional entities and do not necessarily correspond to physically or logically independent entities.

[0040] In this example embodiment, a method for preparing Ti-TiN core-shell powder is first provided. Referring to Figures 1 to 3 as shown, the method includes the following steps:

[0041] Step S101, in the atomization chamber 100, a mixed gas is blown onto the molten pool on the surface of the electrode blank 10 to perform primary refinement and primary coating and nitrogen increment treatment on the droplets formed after melting the electrode blank 10. The mixed gas includes argon and nitrogen, and the volume content of nitrogen does not exceed 10%.

[0042] The electrode blank 10 is selected from pure titanium or titanium alloy blanks. The plasma rotating electrode 30 is started, and the mixed gas composed of argon and nitrogen directly acts on the molten pool of the electrode blank 10. The molten liquid film directly acts with nitrogen, and the liquid film after acting with nitrogen is broken into fine droplets under the action of centrifugal force.

[0043] In the mixed gas composed of argon and nitrogen, the volume content of nitrogen cannot exceed 10%. When the nitrogen content exceeds 10%, the plasma generated by the ionization of argon + nitrogen reacts violently with the molten liquid film, and the molten liquid film leaves the electrode blank 10 under the action of high-speed centrifugal force and cools into powder, but the powder at this time cannot be spherical. When the nitrogen content is less than 10%, the plasma generated by the ionization of argon + nitrogen reacts only on the surface layer of the molten liquid film, and the molten liquid film is broken into spherical powder under the action of high-speed centrifugation. At this time, the surface layer of the formed powder is the TiN core-shell phase produced by the reaction of the plasma flame and the molten pool, and the inside is the pure titanium or titanium alloy raw material phase, forming Ti-TiN core-shell powder. Limited by the reaction time and the degree of reaction intensity, the thickness of the TiN core-shell phase is generally between 10 and 1000 nm at this time, such as 100 nm, 200 nm, 500 nm, etc.

[0044] In addition, the temperature of the mixed gas can be low or high, preferably low. The low-temperature mixed gas can be directly provided by the gas supply equipment without treatment.

[0045] Step S102, high-temperature pure nitrogen is blown onto the droplets separated from the surface of the electrode blank 10 to perform secondary refinement and secondary coating and nitrogen increment treatment on the droplets. The temperature of the high-temperature pure nitrogen is 1000~1500 °C. For example, it can be 1050 °C, 1100 °C, 1300 °C, etc.

[0046] The impact air pressure of the high-temperature pure nitrogen is 1~10 MPa. For example, it can be 2 MPa, 5 MPa, 8 MPa, etc. The impact of the high-temperature nitrogen plays a role in secondary gas fragmentation refinement and secondary coating and nitrogen increment on the droplets broken by centrifugation. The high-temperature pure nitrogen can maintain the temperature of the droplets, hinder the cooling process of the droplets, increase the reaction time between the powder and nitrogen, so as to ensure that the outer surface of the droplets continues to react with nitrogen and continuously generate TiN. The high-pressure high-temperature pure nitrogen can be secondarily fragmented through a circular powder fragmentation spray disc, and the fragmented powder enters the powder collection bucket through a pipeline, and the high-temperature pure nitrogen is discharged separately through a specific pipeline without remaining in the atomization chamber 100.

[0047] Step S103: Use the electrostatic separation device 200 to separate the insufficiently coated powder and the sufficiently coated powder.

[0048] The powder falling from the atomization chamber 100 first enters the powder collection bucket 20. A valve is provided below the powder collection bucket 20, and the powder is discharged through the valve. The electrostatic separation device 200 can be arranged below this valve, and the rate of powder entering the electrostatic separation device 200 is controlled by adjusting the opening of the valve. Optionally, low-temperature argon gas is passed through the pipeline below the valve to further cool and disperse the falling powder.

[0049] The electric field strength of the electrostatic separation device 200 is set between 2 and 5 kV / cm (equipped with a high-voltage power supply of 10 - 30 kV, adjustable), the distance between the electrodes is set between 2 and 5 cm, and the number of electrodes is set to be between 1 and 3. The principle of electrostatic separation is based on the difference in charge accumulation of particles in the electric field. By adjusting parameters such as the electric field strength, polarity, and particle flow rate, the difference in charge accumulation causes the insufficiently coated powder and the sufficiently coated powder to be subjected to different forces in the electric field, thereby achieving separation. Through this method, the insufficiently coated powder and the sufficiently coated powder can be accurately separated. Titanium alloy powders without a core-shell structure and titanium alloy powders with a core-shell structure coverage rate of less than 90% on the surface are both insufficiently coated powders.

[0050] It should be noted that the resistivity of TiN ceramics is: 10 -3 ~10 -2 Ω·m, and the resistivity of conventional titanium alloys is: 4.0×10 -8 ~8.0×10 -8 Ω·m. In the electrostatic separation device 200, the difference in resistivity will lead to different electrostatic behaviors, so that separation can be carried out using electrostatic force. Specifically, for titanium alloy powders without a core-shell structure, titanium alloy powders with a core-shell structure coverage rate of less than 90% on the surface, and fully coated titanium alloy Ti-TiN core-shell powders, there are obvious differences in the resistivity of these three types of powders. These three types of powders can be accurately separated by adjusting the process parameters of the electrostatic separation device 200.

[0051] Step S104: Return the insufficiently coated powder to the atomization chamber 100 for three times of coating and nitrogen addition treatment, or use TiN high-temperature gas to perform three times of coating and nitrogen addition treatment on the powder, and cool the powder after three times of coating and nitrogen addition treatment and the sufficiently coated powder to obtain Ti-TiN core-shell structure powder. Through three times of coating and nitrogen addition treatment, the thickness of the core-shell structure of the powder can be further increased.

[0052] By the above method, a mixed gas of nitrogen and argon is used to refine the droplets once and perform a nitrogen-enriching treatment by coating once. High-temperature pure nitrogen gas is used to refine the droplets twice and perform a nitrogen-enriching treatment by coating twice. Then, the electrostatic force is used to separate the powders that are not fully coated. Then, a nitrogen-enriching treatment by coating three times is performed, so that the prepared powders are Ti-TiN core-shell powders with a large thickness and fineness, a high yield, a uniform shell structure, a high powder sphericity, and a high preparation efficiency.

[0053] This application also provides a method for preparing Ti-TiN core-shell powders. The difference from the foregoing embodiments is that the powders that are not fully coated are subjected to a nitrogen-enriching treatment by coating three times using a nitriding furnace, and the powders after the nitrogen-enriching treatment by coating three times and the fully coated powders are cooled to obtain Ti-TiN core-shell structure powders.

[0054] For example, a high-temperature conveyor belt type nitriding furnace can be used for the nitrogen-enriching treatment by coating three times. The nitriding furnace is filled with high-pressure nitrogen gas. The high-temperature and high-pressure environment can ensure the direct nitriding of the powders and accelerate the reaction rate. A conveyor belt is installed in the nitriding furnace. The upper surface of the conveyor belt is made of high-temperature resistant ceramic material, which can prevent the reaction between the powders and it. Optionally, a high-frequency vibration device can be installed below the conveyor belt to improve the mutual adhesion of the powders in the nitriding furnace.

[0055] In addition, a finished product core-shell powder collection bucket can be arranged below the end of the conveyor belt of the nitriding furnace. Above the collection bucket and at the end of the conveyor belt, there is also a high-speed low-temperature nitrogen gas nozzle directly connected to a nitrogen gas cylinder or a liquid nitrogen tank. The high-speed low-temperature nitrogen gas output from the nitrogen gas cylinder or the liquid nitrogen tank directly acts on the powders at the end of the conveyor belt. The impact of the high-speed low-temperature nitrogen gas can ensure that the powders just passing through the high-temperature nitriding furnace are quickly cooled, and the powders adhered at high temperature are quickly separated. The powders fall into the finished product core-shell powder collection bucket for collection after being acted on by the high-speed low-temperature nitrogen gas.

[0056] There is a high-temperature nitrogen gas delivery port above the high-temperature nitriding furnace to provide high-temperature and high-pressure nitrogen gas for the secondary refinement and secondary nitrogen-enriching treatment by coating in the atomization chamber 100. The nitriding furnace is also provided with a low-temperature nitrogen gas inlet and a high-temperature nitrogen gas outlet. On the one hand, it ensures the stability of the gas pressure in the nitriding furnace and the process consistency of the nitrogen-enriching process; on the other hand, the low-temperature nitrogen gas plays a role in cooling and dispersing the powders, and the high-temperature nitrogen gas plays a role in secondary nitrogen-enriching by coating. This structural design maximizes the reduction of the production cost of the powders while ensuring the high-quality and high-efficiency preparation of the target Ti-TiN core-shell powders.

[0057] In this exemplary embodiment, a device for preparing Ti-TiN core-shell powders is also provided. The method described in any of the above embodiments is used to prepare Ti-TiN core-shell powders. The device includes: an atomization chamber 100, an electrostatic separation device 200, and a three-time nitrogen-enriching treatment by coating device 300.

[0058] Specifically, a first gas blowing device 101 and a second gas blowing device 102 are provided in the atomization chamber 100. The first gas blowing device 101 is used to blow a mixed gas onto the molten pool on the surface of the electrode blank 10, and the second gas blowing device 102 is used to blow high-temperature pure nitrogen onto the droplets flying out from the surface of the electrode blank 10.

[0059] The electrostatic separation device 200 is used to separate the insufficiently coated powder and the sufficiently coated powder.

[0060] The three-time coating and nitrogen increasing treatment device 300 is used to perform three-time coating and nitrogen increasing treatment on the insufficiently coated powder.

[0061] In this embodiment, a mixed gas of nitrogen and argon is used to perform primary refinement and primary coating and nitrogen increasing treatment on the droplets, high-temperature pure nitrogen is used to perform secondary refinement and secondary coating and nitrogen increasing treatment on the droplets, then the electrostatic force is used to separate the insufficiently coated powder, and the three-time coating and nitrogen increasing treatment device 300 is used to perform three-time coating and nitrogen increasing treatment, so that the prepared powder has a Ti-TiN core-shell powder with a large thickness and a small fineness, a high yield, a uniform shell layer structure, a high powder sphericity, and a high preparation efficiency.

[0062] The three-time coating and nitrogen increasing treatment device 300 includes a pressure vessel, in which a non-transfer arc type nitrogen-excited plasma torch is arranged. A pure titanium target is oppositely installed to the non-transfer arc type nitrogen-excited plasma torch. Under the action of the nitrogen plasma torch, the pure titanium target is heated and evaporated and reacts with nitrogen to synthesize TiN high-temperature gas.

[0063] The powder passing through the high-concentration TiN high-temperature steam is rapidly cooled by low-temperature argon or nitrogen after exiting the pressure vessel. Through the extremely cold action of the reaction in the pressure vessel and the low-temperature gas provided by the cooling device 400, the thickness of the core-shell powder increases, and a layer of nano-TiN particles is evenly distributed on the powder surface, forming a double-layer core-shell structure of Ti-TiN core-shell + nano-TiN.

[0064] It should be noted that this part of the high-temperature steam that does not wrap the powder after being cooled by the low-temperature gas will directly form separate nano-TiN powder. There will be nano-particles on the surface of the micron powder. A cyclone separator and a mechanical pump are installed at the rear end, and the separate nano-particles and the coated powder are separated by the action of air flow suction and cyclone separation centrifugal force.

[0065] It should be noted that the gas volumes blown by the first gas blowing device 101 and the second gas blowing device 102 are controlled to avoid affecting each other's content and reaction.

[0066] It should be understood that the orientation or positional relationships indicated by the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc. that may appear in the above description are based on the orientation or positional relationships shown in the drawings. These are only for the convenience of describing the embodiments of the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation on the embodiments of the present invention.

[0067] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the embodiments of the present invention, "a plurality" means two or more, unless otherwise specifically defined.

[0068] In the embodiments of the present invention, unless otherwise clearly specified and limited, terms such as "mounted", "connected", "connected to", "fixed" and the like should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection or integrated; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the communication inside two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0069] In the embodiments of the present invention, unless otherwise clearly specified and limited, the first feature being "above" or "below" the second feature may include the first and second features being in direct contact, or may include the first and second features not being in direct contact but being in contact through additional features therebetween. Moreover, the first feature being "above", "over" and "on top of" the second feature includes the first feature being directly above and obliquely above the second feature, or merely indicating that the first feature is at a higher horizontal level than the second feature. The first feature being "below", "under" and "beneath" the second feature includes the first feature being directly below and obliquely below the second feature, or merely indicating that the first feature is at a lower horizontal level than the second feature.

[0070] In the description of the present specification, the descriptions referring to the terms "one embodiment", "some embodiments", "example", "specific example" or "some examples", etc. mean that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In the present specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine the different embodiments or examples described in the present specification.

[0071] Other embodiments of the present invention will be readily apparent to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of the invention, which follow the general principles of the invention and include known common knowledge or conventional technical means in the technical field not disclosed by the present invention. The specification and examples are only to be considered as exemplary, and the true scope and spirit of the invention are pointed out by the appended claims.

Claims

1. A method for preparing Ti-TiN core-shell powder, characterized in that, The method includes: In an atomization chamber, a mixed gas is blown onto the molten pool on the surface of the electrode rod stock to perform primary refinement and primary coating and nitrogen increment treatment on the droplets formed after melting the electrode rod stock. The mixed gas includes argon and nitrogen, and the volume content of nitrogen does not exceed 10%; High-temperature pure nitrogen is blown onto the droplets separated from the surface of the electrode rod stock to perform secondary refinement and secondary coating and nitrogen increment treatment on the droplets. The temperature of the high-temperature pure nitrogen is 1000 - 1500 °C; An electrostatic separation device is used to separate the insufficiently coated powder and the sufficiently coated powder; The insufficiently coated powder is returned to the atomization chamber for tertiary coating and nitrogen increment treatment, or the powder is subjected to tertiary coating and nitrogen increment treatment using TiN high-temperature gas. After the tertiary coating and nitrogen increment treatment, the powder and the sufficiently coated powder are cooled to obtain Ti-TiN core-shell structure powder.

2. The method for preparing the Ti-TiN core-shell powder according to claim 1, wherein The high-temperature pure nitrogen is blown onto the droplets flying out around the electrode rod stock, and the pressure of the high-temperature pure nitrogen is 1 - 10 MPa.

3. The method for preparing the Ti-TiN core-shell powder according to claim 1, characterized in that, The nitrogen content in the atomization chamber is detected to ensure that the volume content of nitrogen in the mixed gas does not exceed 10%.

4. The method for preparing the Ti-TiN core-shell powder according to claim 1, characterized in that, The electric field strength in the electrostatic separation device is 2 - 5 kV / cm.

5. A method for preparing Ti-TiN core-shell powder, characterized in that, The method includes: In an atomization chamber, a mixed gas is blown onto the molten pool on the surface of the electrode rod stock to perform primary refinement and primary coating and nitrogen increment treatment on the droplets formed after melting the electrode rod stock. The mixed gas includes argon and nitrogen, and the volume content of nitrogen does not exceed 10%; High-temperature pure nitrogen is blown onto the droplets separated from the surface of the electrode rod stock to perform secondary refinement and secondary coating and nitrogen increment treatment on the droplets. The temperature of the high-temperature pure nitrogen is 1000 - 1500 °C; An electrostatic separation device is used to separate the insufficiently coated powder and the sufficiently coated powder; The insufficiently coated powder is subjected to tertiary coating and nitrogen increment treatment using a nitriding furnace. After the tertiary coating and nitrogen increment treatment, the powder and the sufficiently coated powder are cooled to obtain Ti-TiN core-shell structure powder.

6. An apparatus for preparing Ti-TiN core-shell powder, characterized in that, The method according to any one of claims 1 to 5 is used for the preparation of Ti-TiN core-shell powder. The device includes: An atomization chamber, in which a first gas blowing device and a second gas blowing device are provided. The first gas blowing device is used to blow a mixed gas onto the molten pool on the surface of the electrode rod stock, and the second gas blowing device is used to blow high-temperature pure nitrogen onto the droplets flying out from the surface of the electrode rod stock; An electrostatic separation device for separating the insufficiently coated powder and the sufficiently coated powder; A tertiary coating and nitrogen increment treatment device for performing tertiary coating and nitrogen increment treatment on the insufficiently coated powder.

7. The device for preparing the Ti-TiN core-shell powder according to claim 6, wherein, The tertiary coating and nitrogen increment treatment device is a nitriding furnace.

8. The apparatus for preparing the Ti-TiN core-shell powder according to claim 6, characterized in that, The tertiary coating and nitrogen increment treatment device includes: A pressure vessel, in which a non-transferred arc type nitrogen-excited plasma torch is arranged. A pure titanium target is oppositely installed to the plasma torch. Under the action of the plasma torch, the pure titanium target is heated and evaporated and reacts with nitrogen to synthesize TiN high-temperature gas.

9. The device for preparing the Ti-TiN core-shell powder according to any one of claims 6 to 8, characterized in that, The device for preparing Ti-TiN core-shell powder further includes: Cooling device, used for cooling the powder after being processed by the three-time coating and nitrogen-increasing treatment device.

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