Method and device for preparing Ti-TiN core-shell powder

Abstract

The invention relates to a method and device for preparing Ti-TiN core-shell powder, and the method comprises the steps that in an atomizing chamber, mixed gas is blown to a molten pool on the surface of an electrode bar, liquid drops are subjected to primary refining and primary coating nitrogen increasing treatment, the mixed gas comprises argon and nitrogen, and the volume content of the nitrogen does not exceed 10%; high-temperature pure nitrogen is blown to the flying liquid drops, so that secondary refining and secondary coating nitrogen increasing treatment are carried out, and the temperature of the high-temperature pure nitrogen is 1000-1500 DEG C; the powder which is not fully coated and the powder which is fully coated are separated through an electrostatic separation device; and the powder which is not fully coated is subjected to third-time coating nitrogen increasing treatment, so that the Ti-TiN core-shell structure powder is obtained. The prepared powder is core-shell powder with large thickness and small fineness, the yield is high, the shell layer structure is uniform, the sphericity degree of the powder is high, and the preparation efficiency is high.

Description

Technical Field

[0001] Embodiments of the present invention relate to the technical field of atomization powder making, and particularly to a method and 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 propellers 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. Through the nitriding method of metallic titanium powder, its surface is coated and modified to form titanium-titanium nitride (Ti-TiN) core-shell structure powder. The outer shell of titanium nitride can effectively improve the corrosion resistance, oxidation resistance, tensile strength and ductility of this core material of metallic titanium powder, providing raw materials for additive manufacturing and powder metallurgy processes of titanium matrix composites to manufacture precipitation dispersion strengthened alloys. The metallic titanium core-shell structure 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] Traditional preparation of 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 metallic titanium powder collide strongly in a nitrogen or ammonia environment for nitriding. The main means of in-situ reaction coating of titanium powder include 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 treatment 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 thermally evaporating active groups to coat and deposit on the powder surface or by using the interaction between a mixed gas and the surface of the substrate. The titanium core-shell powder prepared by traditional powder coating methods 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 merely because it is included in this part. Summary of the Invention

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

[0007] The present invention first provides a method for preparing Ti-TiN core-shell powder, and the method includes: In an atomization chamber, a mixed gas is blown onto the molten pool on the surface of the electrode rod to perform primary refinement and primary coating and nitrogen increment treatment on the droplets formed after melting the electrode rod. 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 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 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 structure powder.

[0008] In the present invention, the high-temperature pure nitrogen is blown onto the droplets flying out around the electrode rod, and the pressure of the high-temperature pure nitrogen is 1-10 MPa.

[0009] 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%.

[0010] In the present invention, the electric field strength in the electrostatic separation device is 2-5 kV / cm.

[0011] The present invention also provides a method for preparing Ti-TiN core-shell powder, and the method includes: In an atomization chamber, a mixed gas is blown onto the molten pool on the surface of the electrode rod to perform primary refinement and primary coating and nitrogen increment treatment on the droplets formed after melting the electrode rod. 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 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. The powder after the tertiary coating and nitrogen increment treatment and the sufficiently coated powder are cooled to obtain Ti-TiN core-shell structure powder.

[0012] The present invention secondly provides a device for preparing Ti-TiN core-shell powder, and 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 material, 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 material; An electrostatic separation device for separating the insufficiently coated powder and the sufficiently coated powder; A three-time coating and nitrogen increasing treatment device for performing a three-time coating and nitrogen increasing treatment on the insufficiently coated powder.

[0013] In the present invention, the three-time coating and nitrogen increasing treatment device is a nitriding furnace.

[0014] In the present invention, the three-time coating and nitrogen increasing treatment device includes: A pressure vessel, in which a non-transfer arc type nitrogen-excited plasma torch is arranged. An opposite side of the plasma torch is installed with a pure titanium target. 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.

[0015] In the present invention, the device for preparing the Ti-TiN core-shell powder further includes: A cooling device for cooling the powder after being treated by the three-time coating and nitrogen increasing treatment device.

[0016] The technical solution provided by the present invention may include the following beneficial effects: In the present invention, through the above method and device, the droplets are subjected to primary refinement and primary coating and nitrogen increasing treatment by using a mixed gas of nitrogen and argon, and are subjected to secondary refinement and secondary coating and nitrogen increasing treatment by using high-temperature pure nitrogen. Then, the insufficiently coated powder is separated by using electrostatic force, and then a three-time coating and nitrogen increasing treatment is performed, 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. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The accompanying drawings here are incorporated into the specification 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. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0018] Figure 1 A flowchart showing the method for preparing the Ti-TiN core-shell powder in an exemplary embodiment of the present invention; Figure 2 A structural diagram showing the device for preparing the Ti-TiN core-shell powder in an exemplary embodiment of the present invention; Figure 3 Schematic structural diagram of a system for preparing Ti-TiN core-shell powder in an exemplary embodiment of the present invention is shown.

[0019] Reference numerals: 10, electrode rod stock; 20, powder collection barrel; 30, plasma rotating electrode 100, atomization chamber; 101, first gas blowing device; 102, second gas blowing device; 200, electrostatic separation device; 300, three-time coating and nitrogen increment treatment device; 400, cooling device. Detailed implementation manners

[0020] 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 may be combined in any suitable manner in one or more embodiments.

[0021] 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.

[0022] 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: Step S101, in the atomization chamber 100, a mixed gas is blown onto the molten pool on the surface of the electrode rod stock 10 to perform primary refinement and primary coating and nitrogen increment treatment on the droplets formed after melting the electrode rod stock 10. The mixed gas includes argon and nitrogen, and the volume content of nitrogen does not exceed 10%.

[0023] The electrode rod stock 10 is selected as a pure titanium or titanium alloy rod stock. 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 rod stock 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.

[0024] In the mixed gas composed of argon and nitrogen, the volume content of nitrogen shall not exceed 10%. When the nitrogen content exceeds 10%, the plasma generated by the ionization of argon + nitrogen reacts violently with the molten liquid film. Under the action of high-speed centrifugal force, the molten liquid film leaves the electrode rod and cools into powder at 10, but the powder cannot be spherical at this time. When the nitrogen content is less than 10%, the plasma generated by the ionization of argon + nitrogen reacts only on the surface layer with the molten liquid film. 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.

[0025] In addition, the temperature of the mixed gas can be low temperature or high temperature, preferably low temperature. The low-temperature mixed gas can be directly provided by the gas supply equipment without treatment.

[0026] Step S102, blowing high-temperature pure nitrogen gas to the droplets separated from the surface of the electrode rod 10 to perform secondary refinement and secondary coating nitrogen addition treatment on the droplets. The temperature of the high-temperature pure nitrogen gas is 1000~1500 °C. For example, it can be 1050 °C, 1100 °C, 1300 °C, etc.

[0027] The impact air pressure of the high-temperature pure nitrogen gas is 1~10 MPa. For example, it can be 2 MPa, 5 MPa, 8 MPa, etc. The impact of high-temperature nitrogen gas plays a role in secondary gas fragmentation refinement and secondary coating nitrogen addition on the droplets broken by centrifugation. The high-temperature pure nitrogen gas can maintain the temperature of the droplets, hinder the cooling process of the droplets, increase the reaction time between the powder and nitrogen gas, so as to ensure that the outer surface of the droplets continues to react with nitrogen gas and continuously generate TiN. The high-pressure high-temperature pure nitrogen gas can be secondarily fragmented through a circular powder fragmentation spraying disc. The fragmented powder enters the powder collection bucket through a pipeline, and the high-temperature pure nitrogen gas is discharged separately through a specific pipeline without remaining in the atomization chamber 100.

[0028] Step S103, using the electrostatic separation device 200 to separate the insufficiently coated powder and the sufficiently coated powder.

[0029] The powder falling from the atomization chamber 100 first enters the powder collection bucket 20. A valve is set below the powder collection bucket 20, and the powder is discharged through the valve. The electrostatic separation device 200 can be set 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.

[0030] 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 an electric field. By adjusting parameters such as the electric field strength, polarity, and particle flow rate, the difference in charge accumulation causes the uncoated powder and the fully coated powder to be subjected to different forces in the electric field, thus achieving separation. By this method, the uncoated powder and the fully coated powder can be accurately separated. Titanium alloy powder without a core-shell structure and titanium alloy powder with a core-shell structure coverage rate of less than 90% on the surface are both uncoated powders.

[0031] It should be noted that the resistivity of TiN ceramic is: 10 -3 ~10 -2 Ω·m, and the resistivity of conventional titanium alloy is: 4.0×10 -8 ~8.0×10 -8 Ω·m. In the electrostatic separation device 200, the resistivity difference will lead to different electrostatic behaviors, so that separation can be carried out using electrostatic force. Specifically, for titanium alloy powder without a core-shell structure, titanium alloy powder with a core-shell structure coverage rate of less than 90% on the surface, and fully coated titanium alloy Ti-TiN core-shell powder, the resistivity of these three types of powder is significantly different. These three types of powder can be accurately separated by adjusting the process parameters of the electrostatic separation device 200.

[0032] Step S104, return the uncoated powder to the atomization chamber 100 for three times of coating and nitrogen addition treatment, or use high-temperature TiN 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 fully 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.

[0033] By the above method, a mixed gas of nitrogen and argon is used to perform primary atomization and primary coating and nitrogen addition treatment on the droplets, high-temperature pure nitrogen is used to perform secondary atomization and secondary coating and nitrogen addition treatment on the droplets, then the uncoated powder is separated by electrostatic force, and then three times of coating and nitrogen addition treatment are carried out, so that the prepared powder has 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.

[0034] The present application also provides a method for preparing Ti-TiN core-shell powder. The difference from the foregoing embodiments is that the insufficiently coated powder is subjected to three times of coating and nitrogen increasing treatment by using a nitriding furnace, and the powder after the three times of coating and nitrogen increasing treatment and the sufficiently coated powder are cooled to obtain Ti-TiN core-shell structured powder.

[0035] For example, a high-temperature conveyor belt type nitriding furnace can be used for the three times of coating and nitrogen increasing treatment. The nitriding furnace is filled with high-pressure nitrogen gas. The high-temperature and high-pressure environment can ensure direct nitriding of the powder and accelerate the reaction speed. A conveyor belt is installed in the nitriding furnace, and the upper surface of the conveyor belt is made of high-temperature resistant ceramic material, which can prevent the powder from reacting with it. Optionally, a high-frequency vibration device can be installed below the conveyor belt to improve the mutual adhesion of the powder in the nitriding furnace.

[0036] 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 additionally a high-speed low-temperature nitrogen gas nozzle, which is 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 powder at the end of the conveyor belt. The impact of the high-speed low-temperature nitrogen gas can ensure that the powder just passing through the high-temperature nitriding furnace is quickly cooled, and the powder adhered at high temperature is quickly separated. The powder falls into the finished product core-shell powder collection bucket for collection after being acted on by the high-speed low-temperature nitrogen gas.

[0037] 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 coating and nitrogen increasing treatment 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 increasing process; on the other hand, the low-temperature nitrogen gas plays a role in cooling and dispersing the powder, and the high-temperature nitrogen gas plays a role in secondary coating and nitrogen increasing. This structural design maximizes the reduction of the production cost of the powder while ensuring the high-quality and high-efficiency preparation of the target Ti-TiN core-shell powder.

[0038] In this exemplary embodiment, a device for preparing Ti-TiN core-shell powder is also provided. The method described in any one of the foregoing embodiments is used to prepare the Ti-TiN core-shell powder. The device includes: an atomization chamber 100, an electrostatic separation device 200, and a three-time coating and nitrogen increasing treatment device 300.

[0039] Specifically, a first gas blowing device 101 and a second gas blowing device 102 are arranged in the atomization chamber 100. The first gas blowing device 101 is used to blow a mixed gas to the molten pool on the surface of the electrode rod 10, and the second gas blowing device 102 is used to blow high-temperature pure nitrogen gas to the droplets flying out from the surface of the electrode rod 10.

[0040] The electrostatic separation device 200 is used to separate the insufficiently coated powder and the sufficiently coated powder.

[0041] The three - layer coating and nitrogen - increasing treatment device 300 is used to perform three - layer coating and nitrogen - increasing treatment on the insufficiently coated powder.

[0042] In this embodiment, a mixed gas of nitrogen and argon is used to perform primary droplet refinement and primary coating and nitrogen - increasing treatment on the droplets, high - temperature pure nitrogen is used to perform secondary droplet 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 - layer coating and nitrogen - increasing treatment device 300 is used to perform three - layer coating and nitrogen - increasing treatment, so that the prepared powder is Ti - TiN core - shell powder with a large thickness and a small fineness, a high yield, a uniform shell structure, a high powder sphericity, and a high preparation efficiency.

[0043] The three - layer coating and nitrogen - increasing treatment device 300 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 non - transferred arc - type nitrogen - excited plasma torch, and 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.

[0044] 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 effect of the reaction in the pressure vessel and the low - temperature gas provided by the reaction and 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.

[0045] 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 - sized 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.

[0046] 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.

[0047] It should be understood that the orientation or positional relationships indicated by terms such as "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. They are only for the convenience of describing the embodiments of the present invention and simplifying the description, rather than indicating or implying 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.

[0048] In addition, the terms "first" and "second" are only used for descriptive purposes and should not 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, the meaning of "a plurality" is two or more, unless otherwise specifically defined.

[0049] In the embodiments of the present invention, unless otherwise clearly specified and limited, terms such as "mounted", "connected", "connected to", "fixed" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection or integrated; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can 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.

[0050] 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 direct contact between the first and second features, or may include the situation where the first and second features are not in direct contact but in contact through additional features therebetween. Moreover, the first feature being "above", "above and over" and "on the top of" the second feature includes that the first feature is directly above and obliquely above the second feature, or merely indicates that the horizontal height of the first feature is higher than that of the second feature. The first feature being "below", "below and under" and "under the bottom of" the second feature includes that the first feature is directly below and obliquely below the second feature, or merely indicates that the horizontal height of the first feature is lower than that of the second feature.

[0051] In the description of this specification, the description referring to terms such as "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" means 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 this 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 can be combined in a suitable manner in any one or more embodiments or examples. In addition, those skilled in the art can combine and combine the different embodiments or examples described in this specification.

[0052] After considering the specification and practicing the invention disclosed herein, other embodiments of the present invention will readily occur to those skilled in the art. This application is intended to cover any variations, uses, or adaptations of the present invention, which follow the general principles of the present 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 regarded as exemplary, and the true scope and spirit of the present 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 the 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 structured 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, wherein, 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, wherein, 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 the 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 structured powder.

6. An apparatus for preparing Ti-TiN core-shell powder, characterized in that, The method according to any one of claims 1 - 5 is adopted 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 apparatus 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 apparatus 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 to cool the powder after being processed by the triple coating and nitrogen increasing treatment device.

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