Device and method for preparing thermal spraying coated powder

Abstract

The invention relates to the technical field of composite powder preparation, and provides a device and method for preparing thermal spraying coated powder.The device comprises a shell powder melting system, a core powder conveying system and a coated powder collecting system.The shell powder and the core powder are subjected to ball milling, dispersing, drying and screening respectively, and then the coated powder is obtained; a shell powder melting system is used for heating shell powder to be in a molten state and spraying the shell powder out along with high-temperature flame flow, and meanwhile a core powder conveying system is used for vertically conveying core powder into the high-temperature flame flow containing the molten shell powder at a certain air pressure and a certain distance, so that the surface of the core powder is evenly coated with the molten shell powder; and further drying, screening and plasma spheroidizing the coated powder which flies out of the high-temperature flame flow and is solidified to form a semi-finished product by using a coated powder collecting device, so as to obtain the target coated powder. The method is simple in process and high in powder preparation efficiency, the shell powder and the core powder in the prepared coated powder are uniformly coated, the coated powder has a good spherical structure, and the coated powder is suitable for preparing a multi-component thermal spraying coating.

Description

Technical Field

[0001] The invention belongs to the technical field of composite powder preparation, and in particular relates to a device and method for preparing thermal spray coating powder. Background Art

[0002] Thermal spraying is a commonly used coating preparation process. Its principle is to use electric arc, plasma or flame as a heat source to heat materials such as powder, suspension and wire to a molten or semi-molten state, spray it onto the surface of the workpiece, and deposit-stack-solidify to form a coating. It is a surface treatment technology that can be used to prepare metal coatings, intermetallic compound coatings and inorganic non-metallic coatings. Thermal spraying has relatively stringent requirements on the physical properties of powder materials, such as: being as spherical as possible, the powder particle size is between 5μm-120μm, insoluble in water and having good dispersibility and fluidity. However, single-component thermal spray powders have gradually failed to meet the application requirements of coatings in industrial production. The need to use multi-element composite powders to achieve better protective performance of thermal spray coatings and improve the functionality of coatings is becoming increasingly urgent.

[0003] Common composite powder preparation methods for thermal spray powder include agglomeration spray granulation, solid phase coating, and liquid phase coating. In the agglomeration spray granulation method, A element powder and B element powder are prepared into slurry, and then the A+B coated powder is prepared by bonding with a binder through a spray granulator. The slurry of A and B element powders randomly agglomerates and combines during the granulation process, making it difficult to make each powder A+B compound in an agreed proportion, resulting in uneven coating composition, affecting the protectiveness and functionality of the composite coating; when the melting point difference between A and B element powders is too large, it is easy to cause adverse effects such as the low melting point component melting while the high melting point component is not melted, or the high melting point component melting and the low melting point component gasifying; the solid phase coating method uses mechanical ball milling to achieve the coating of the two powders; the liquid phase coating method uses the shell powder to be prepared in the form of a sol or suspension, and uses a chemical method to achieve the coating of the shell powder and the core powder. However, the solid-phase coating method or liquid-phase coating method has complex processes and low powder making efficiency, and is difficult to apply to the preparation of shell powder in inorganic non-metallic coated powders with poor ductility, insolubility in organic matter, and high melting point.

[0004] Secondly, for the patent number CN107034428A, the invention name is: A ceramic-coated organic composite powder suitable for spraying and its spraying method, the nano-level A element powder and the micron-level B element powder are dispersed, mixed, and prepared into a slurry, and then a spherical composite coated powder is prepared using an agglomeration spray granulator. The nano-level powder in this method is easy to spontaneously agglomerate due to its large specific surface area, and it is not easy to disperse when preparing the mixed slurry. In addition, the slurry of the two element powders A and B randomly agglomerates and combines during the spray granulation process, making it difficult to make each powder A+B compound in an agreed proportion, resulting in uneven coating composition. For the patent number CN110695365A, the invention name is: A method and device for preparing metal mold coated powder by gas-solid two-phase atomization, the metal shell powder is heated to a molten state by the device, and then the core powder is combined with the atomized metal shell powder using high-pressure gas to form a metal mold coated powder. The atomizing nozzle in the device uses a Laval or contraction type atomizing nozzle, which is very easy to be blocked when encountering molten shell powder materials with high melting point and poor fluidity, affecting production efficiency.

[0005] In view of this, this invention is proposed. Summary of the invention

[0006] The purpose of the present invention is to overcome the shortcomings of the above-mentioned prior art and provide a device and method for preparing thermal spray coated powder, which solves the problem that in the process of preparing A+B coated powder by traditional spray granulation method, the slurry of A and B element powders randomly agglomerates and combines during the spray granulation process, making it difficult to make each powder A+B compound in an agreed proportion, resulting in uneven coating composition; at the same time, it solves the problem that when the melting point difference between A and B element powders is too large, the low melting point component melts and the high melting point component does not melt, or the high melting point component melts and the low melting point component vaporizes, resulting in adverse effects; it also solves the problem that the solid phase coating method and the liquid phase coating method have complex processes, low powder making efficiency, and are difficult to be suitable for the preparation of inorganic non-metallic coated powders with poor ductility, insoluble in water and organic matter, and high melting point.

[0007] The purpose of the present invention is to be solved by the following technical solutions:

[0008] In one aspect, the present invention provides an apparatus for preparing a thermal spray coating powder, comprising:

[0009] Shell powder melting system is used to heat the shell powder to a molten state and eject it with a high-temperature flame.

[0010] The core powder conveying system is used to feed the core powder into the high-temperature flame flow of the molten shell powder, so that the molten shell powder is coated on the surface of the core powder.

[0011] The coating powder collection system is used to collect the semi-finished coating powder that flies out of the high-temperature flame flow and solidifies, and to screen the collected semi-finished coating powder.

[0012] Furthermore, the core powder conveying system includes an air compressor, which is connected to the fluidized bed through a core powder air pipe. The powder outlet end of the fluidized bed is connected to a core powder feeding pipe, and the outlet end of the core powder feeding pipe is connected to a buncher. A pressure gauge is also connected between the air compressor and the core powder air pipe. The fluidized bed is filled with core powder, and the powder outlet end is arranged at the upper end of the fluidized bed.

[0013] Furthermore, the shell powder melting system includes a copper frame arranged in the middle, one end of the copper frame is connected to an inert gas high-pressure gas cylinder, an active gas high-pressure gas cylinder, a barometer, an air pipe, an air compressor, a shell powder feeding tank, a shell powder air pipe and a power supply, the other end of the copper frame is connected to a cathode head and an anode head, and a high-voltage radio frequency generator is installed in the copper frame.

[0014] The inert gas high-pressure cylinder and the active gas high-pressure cylinder are connected in parallel to the air pipe, and a pressure gauge is also provided on the air pipe. One end of the shell powder feeding tank is connected to the air compressor, and the other end is connected to the shell powder air pipe. The air pipe and the shell powder air pipe are connected to the air inlet pipe in the copper frame. The air inlet pipe passes through the copper frame and is connected to the powder outlet provided on the cathode head.

[0015] The cathode head and the anode head are both installed on the insulator seat. The negative pole of the power supply enters from one end of the copper frame through a cable, and is connected to the high-voltage radio frequency generator in turn and then connected to the cathode head. One end of the anode head is connected to the positive pole of the power supply through a cable. The cavity with one end open surrounded by the anode head and the cathode head is a discharge chamber. The high-voltage radio frequency generator increases the voltage in the discharge chamber exponentially to generate a plasma arc in the discharge chamber. The air compressor is connected to the shell powder feeding tank through an air pipe, and the powder is fed into the plasma arc through the shell powder air pipe by conveying carrier gas to form a molten powder jet.

[0016] A water inlet and a water outlet are connected to the outside of the copper frame. Flowing water enters from the water inlet, is circulated and cooled in the outer sleeve of the copper frame, and is discharged from the water outlet.

[0017] Preferably, the gas in the inert gas high-pressure cylinder is any one of nitrogen and argon, the gas in the active gas high-pressure cylinder is hydrogen, the cathode head is made of graphite or silver-based alloy, and the insulator seat is made of aluminum oxide or silicon nitride.

[0018] Furthermore, the coated powder collecting system comprises a powder collecting trough, water is stored inside the powder collecting trough, a filter is installed in the powder collecting trough, and a drainage port is opened at the bottom of the powder collecting trough.

[0019] Furthermore, the mesh size of the filter is 15 to 150 μm.

[0020] On the other hand, the present invention provides a method for preparing a thermal spray coating powder, based on an apparatus for preparing a thermal spray coating powder, comprising the following steps:

[0021] S1. Raw material pretreatment: The shell powder and the core powder are ball-milled, respectively, and the shell powder and the core powder after ball milling are dispersed, and then, the shell powder and the core powder of the desired particle size are obtained by drying and sieving;

[0022] S2. Preparation of semi-finished coated powder: The shell powder and core powder obtained in step S1 are respectively placed in a shell powder melting system and a core powder conveying system, the shell powder in a molten state is ejected through a high-temperature flame flow, and the core powder is vertically fed into the high-temperature flame flow containing molten shell powder at a certain pressure and distance, the molten shell powder is coated on the surface of the core powder, and flies out of the high-temperature flame flow to solidify to form a semi-finished coated powder;

[0023] S3. Pretreatment of semi-finished coated powder: The semi-finished coated powder obtained in step S2 is collected by a coated powder collection system and then sieved and dried to obtain a coated powder;

[0024] S4. Coating powder shaping treatment: The coating powder obtained in step S3 is subjected to plasma spheroidization treatment by plasma spraying equipment, and then dried to obtain the target coating powder.

[0025] Furthermore, the specific steps of the ball milling treatment in step S1 are: using a dry ball mill, using ceramic balls with a diameter of 3 to 20 mm to ball mill the raw materials, with a ball-to-material ratio of 1.5 to 7:1, and a ball mill speed of 30 to 90 r / min,

[0026] The specific steps of the dispersion treatment are: adding the ball-milled powder to a dispersant and deionized water and stirring for 30 to 60 minutes, wherein the mass ratio of the dispersant: the powder: the deionized water is 1: (90 to 120): (80 to 110), the powder is shell powder or core powder, and the dispersant is an ionic or non-ionic dispersant.

[0027] The specific steps of the drying and screening treatment are: placing the dispersed powder into a drying oven, drying at a temperature of 65-90°C for 2-3 hours, and screening out the powder of the desired particle size through a sieve, wherein the particle size of the screened core powder is 5-45 μm, and the particle size of the screened shell powder is 40-120 μm.

[0028] Furthermore, in step S2, the core powder is vertically fed into the high-temperature flame flow containing the molten shell powder at a pressure of 3 to 9 bar and a distance of 40 to 200 mm.

[0029] In step S3, the specific steps of collecting the semi-finished coated powder by the coating powder collection system, drying it and sieving it to obtain the coated powder are as follows: the powder with a particle size larger than the maximum particle size of the core powder is sifted through the filter screen and retained on the surface of the filter screen, the powder retained on the surface of the filter screen is placed in a drying oven, and the coated powder is obtained after drying at 120°C for 2 hours.

[0030] Furthermore, the specific steps of shaping the coated powder in step S4 are as follows: placing the coated powder obtained in step S3 into a plasma spraying device, spraying the coated powder into a water tank filled with a pure aqueous solution, draining the coated powder at the bottom of the water tank, placing it in a drying oven, drying it, and collecting it;

[0031] Spraying parameters are: argon: 20-150L / min, nitrogen: 20-150L / min, hydrogen: 10-40L / min, powder feeding rate: 15-100g / min, spraying distance: 80-260mm, current: 450-550A, carrier gas: 12-18L / min;

[0032] Drying parameters are: temperature: 65~90℃, drying time: 2-3h.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] 1. The target coated powder prepared by the present invention is a shell powder-core powder composite structure. The core powder and the shell powder are both independently fed, which can realize the precise control of the particle size of the conveyed powder, and obtain a multi-component composite coated powder in which the molten shell powder is uniformly coated on the surface of the core powder. The coated powder can meet the requirements of preparing multi-component and uniformly composed thermal spray coatings, and the process is simple and convenient, and the powder making efficiency is high;

[0035] 2. The target coated powder prepared by the present invention adopts plasma spheroidization process in the last step. The target coated powder has high sphericity and good fluidity. After testing, the fluidity of the prepared target coated powder is 35-78s / 50g, and the bulk density is 2.3-4.0g / cm 3 , and inert gas is involved in the powder preparation process, so the powder oxidation degree of the obtained target coated powder is low.

[0036] 3. In the preparation method of the present invention, the flame flow temperature in the shell powder melting system is relatively high, which can realize the coating preparation of molten shell powder and core powder at a relatively high melting point, meet the preparation requirements of various types of high-melting-point metal or non-metallic coating powders for thermal spraying, especially for two powders with a large difference in melting points, can prepare a coating powder in which a larger-sized low-melting-point shell powder is coated with a smaller-sized high-melting-point core powder, and realize the simultaneous melting of the shell powder and the core powder during the spraying process. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The accompanying drawings are incorporated in and constitute a part of this specification and, together with the description, serve to explain the principles of the present invention.

[0038] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0039] Figure 1 It is a schematic structural diagram of a device for preparing thermal spray coating powder according to the present invention;

[0040] Figure 2 It is a schematic structural diagram of a shell powder melting system in a device for preparing thermal spray coating powder of the present invention;

[0041] Figure 3 It is a structural schematic diagram of a core powder material conveying system in a device for preparing thermal spray coating powder of the present invention;

[0042] Figure 4 It is a structural schematic diagram of a coating powder collection system in a device for preparing thermal spray coating powder of the present invention;

[0043] Figure 5 The figure is a schematic diagram of the process of the method for preparing thermal spray coating powder according to the present invention.

[0044] Among them, 1-core powder conveying system, 11-air compressor, 12-pressure gauge, 13-core powder air pipe, 14-fluidized bed, 15-core powder feeding pipe, 16-bundler; 2-shell powder melting system, 201-inert gas high-pressure gas cylinder, 202-active gas high-pressure gas cylinder, 203-pressure gauge, 204-air pipe, 205-air compressor, 206-shell powder feeding tank, 207-shell powder air pipe, 208-power supply, 209-cathode head, 210-anode head, 211-cable, 212-water inlet, 213-water outlet, 214-discharge chamber, 215-air inlet pipe, 216-insulator seat, 217-high-voltage radio frequency generator; 3-coated powder collection system, 31-powder collection trough, 32-filter, 33-drain outlet. DETAILED DESCRIPTION

[0045] Exemplary embodiments will be described in detail herein, examples of which are shown in the accompanying drawings. When the following description refers to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention. Instead, they are merely examples consistent with some aspects of the present invention as detailed in the appended claims.

[0046] According to an embodiment of the present invention, Figure 1 As shown, the present invention provides an apparatus for preparing thermal spray coated powder, comprising: a shell powder melting system 2, used for heating the shell powder to a molten state and spraying it out with a high-temperature flame flow; a core powder conveying system 1, used for conveying the core powder into the high-temperature flame flow of the shell powder in a molten state, so that the molten shell powder is evenly coated on the surface of the core powder; a coating powder collecting system 3, used for collecting semi-finished coated powder formed by solidification outside the high-temperature flame flow, and screening the collected semi-finished coated powder.

[0047] According to an embodiment of the present invention, Figure 3 As shown, the core powder material conveying system 1 includes an air compressor 11, and the air compressor 11 is connected to the fluidized bed 14 through the core powder air pipe 13. The fluidized bed 14 is controlled by the air compressor 11 connected to the core powder air pipe 13 to control the air source input. The powder outlet end of the fluidized bed 14 is connected to the core powder feeding pipe 15, and the outlet end of the core powder feeding pipe 15 is connected to the clustering device 16. A pressure gauge 12 is also connected between the air compressor 11 and the core powder air pipe 13 to monitor the air supply pressure. The fluidized bed 14 is filled with core powder, and the powder outlet end is arranged at the upper end of the fluidized bed 14. Specifically, the shape of the clustering device 16 is an inverted trapezoid or an hourglass shape with one end closed. The lower end of the fluidized bed 14 is provided with a leg for support.

[0048] According to an embodiment of the present invention, Figure 2 As shown, the shell powder melting system 2 includes a copper frame arranged in the middle, one end of the copper frame is connected with an inert gas high-pressure gas cylinder 201, an active gas high-pressure gas cylinder 202, a barometer 203, an air pipe 204, an air compressor 205, a shell powder feeding tank 206, a shell powder air pipe 207 and a power supply 208, and the other end of the copper frame is connected with a cathode head 209 and an anode head 210, and a high-voltage radio frequency generator 217 is installed in the copper frame. The high-voltage radio frequency generator 217 is integrated in a cylindrical copper frame having an inner and outer sleeve sealing structure, and the negative pole of the power supply 208 enters from one end of the inner sleeve of the copper frame through a cable 211, and is connected to the high-voltage radio frequency generator 217 and the cathode head 209 in sequence.

[0049] According to an embodiment of the present invention, an inert gas high-pressure gas cylinder 201 and an active gas high-pressure gas cylinder 202 are connected in parallel to an air pipe 204, and a barometer 203 is also provided on the air pipe 204. Gas is introduced into the plasma arc through the barometer 203 and the air pipe 204 to maintain the continuity of the plasma arc. One end of the shell powder feeding tank 206 is connected to the air compressor 205 through the air pipe, and the other end is connected to the shell powder air pipe 207. The air compressor 205 provides a certain amount of carrier gas to feed the powder into the plasma arc through the shell powder air pipe 207 to form a molten powder jet. The air pipe 204 and the shell powder air pipe 207 are connected to the air inlet pipe 215 in the copper frame, and the air inlet pipe 215 passes through the copper frame and is connected to the powder outlet provided on the cathode head 209. The cathode head 209 and the anode head 210 are both installed on the insulator seat 216. Further, the cathode head 209 and the anode head 210 are blocked and connected by the insulator seat 216. The negative pole of the power source 208 enters from one end of the copper frame through the cable 211, and is connected to the high-voltage radio frequency generator 217 and then to the cathode head 209. One end of the anode head 210 is connected to the positive pole of the power source 208 through the cable 211. The cavity with one end open surrounded by the anode head 210 and the cathode head 209 is the discharge chamber 214. The high-voltage radio frequency generator 217 increases the voltage in the discharge chamber 214 exponentially to generate a plasma arc in the discharge chamber 214. The air compressor 205 is connected to the shell powder feeding tank 206 through an air pipe, and the powder is fed into the plasma arc through the shell powder air pipe 207 by conveying carrier gas to form a molten powder jet. One end of the high-voltage radio frequency generator 217 is connected to the cathode head 209, and the other end is grounded.

[0050] According to an embodiment of the present invention, a water inlet 212 and a water outlet 213 are connected to the outside of the copper frame. Furthermore, the water inlet 212 and the water outlet 213 are connected to the outer sleeve of the copper frame. Flowing water enters from the water inlet 212, is circulated and cooled in the outer sleeve of the copper frame, and is discharged from the water outlet 213 to maintain the temperature of the cylindrical copper frame with the inner and outer sleeve sealing structure.

[0051] According to an embodiment of the present invention, the gas in the inert gas high-pressure gas cylinder 201 is any one of nitrogen and argon, and the gas in the active gas high-pressure gas cylinder 202 is hydrogen.

[0052] According to an embodiment of the present invention, the cathode head 209 is made of graphite or silver-based alloy, and the insulator seat 216 is made of aluminum oxide or silicon nitride.

[0053] According to an embodiment of the present invention, Figure 4As shown, the coated powder collection system 3 includes a powder collection tank 31, water is stored inside the powder collection tank 31, a filter screen 32 arranged horizontally is installed in the powder collection tank 31, and a drain port 33 is opened at the bottom of the powder collection tank 31. The mesh size of the filter screen 32 is 15 to 150 μm. In the specific use process, it is necessary to select a mesh slightly larger than the maximum particle size of the core powder for screening according to the size of the obtained core powder.

[0054] According to an embodiment of the present invention, Figure 5 As shown, the present invention also provides a method for preparing thermal spray coating powder, comprising the following steps:

[0055] S1. Pretreatment of raw materials: Use a dry ball mill and ceramic balls with a diameter of 3 to 20 mm to ball-mill the shell powder and core powder respectively, with a ball-to-material ratio of 1.5 to 7:1 and a ball mill speed of 30 to 90 r / min; add dispersant and deionized water to the shell powder and core powder after ball milling respectively and stir for 30 to 60 minutes, wherein the mass ratio of dispersant: powder: deionized water is 1: (90 to 120): (80 to 110), the powder is shell powder or core powder, and the dispersant is an ionic or non-ionic dispersant; then, put the dispersed powder into a drying oven and dry it at a temperature of 65 to 90°C for 2-3 hours, and sieve out the powder of the desired particle size through a sieve, wherein the particle size of the sieved core powder is 5 to 45 μm, and the particle size of the sieved shell powder is 40 to 120 μm.

[0056] S2. Preparation of semi-finished coated powder: The shell powder and core powder obtained in step S1 are respectively placed in the shell powder melting system 2 and the core powder conveying system 1, and the shell powder in a molten state is sprayed out by the high-temperature flame flow. The core powder is vertically fed into the high-temperature flame flow containing molten shell powder at an air pressure of 3 to 9 bar and a distance of 40 to 200 mm. The molten shell powder is evenly coated on the surface of the core powder, flies out of the high-temperature flame flow and solidifies to form a semi-finished coated powder.

[0057] It should be noted that the distance is 40 to 200 mm when vertically fed into the high-temperature flame flow containing the molten shell powder, that is, the distance from the lower end of the clustering device 16 to the high-temperature flame flow is 40 to 200 mm.

[0058] S3. Pretreatment of semi-finished coated powder: The semi-finished coated powder obtained in step S2 is collected by the coated powder collection system 3, that is, the powder with a particle size larger than the maximum particle size of the core powder is sieved out through the filter 32 and retained on the surface of the filter 32, and the powder retained on the surface of the filter 32 is put into a drying oven and dried at 120°C for 2 hours to obtain the coated powder.

[0059] Specifically, since the collection device 3 is provided with a filter 32, when the powder enters the water in the collection tank 31, at this time, there are coated powders with larger particle sizes and uncoated small particle size core powders in the water. The density of the coated powder is usually greater than that of water and has a certain mass, while the uncoated powder will float on the water surface. The floating powder on the water surface is scooped out with a ladle, and the other part of the powder is precipitated on the surface of the filter 32. The filter 32 is shaken, and the powder of suitable particle size is retained on the surface of the filter, and the unsuitable powder passes through the filter 32 and precipitates to the bottom of the collection tank 31. The drain port 33 is opened to discharge the water and unsuitable powder, and the powder on the surface of the filter 32 is obtained, and then dried at 120°C for 2 hours.

[0060] S4. Coating powder shaping treatment: Put the coating powder obtained in step S3 into the plasma spraying equipment for plasma spheroidization treatment, that is, spray the coating powder into a water tank filled with pure water solution, drain the coating powder at the bottom of the water tank, put it into the drying oven for drying and collection. Spraying parameters are: argon: 20-150L / min, nitrogen: 20-150L / min, hydrogen: 10-40L / min, powder feeding rate: 15-100g / min, spraying distance: 80-260mm, current: 450-550A, carrier gas: 12-18L / min; drying parameters are: temperature: 65-90℃, drying time: 2-3h.

[0061] The present invention provides a device and method for preparing thermal spray coating powder, which comprises the following steps: ball-milling, dispersing, drying and screening the shell powder and the core powder respectively, heating the shell powder to a molten state by using a shell powder melting system and spraying it out with a high-temperature flame flow, and at the same time, using a core powder conveying system to vertically feed the core powder into a high-temperature flame flow containing an excess of molten shell powder at a certain air pressure and distance, so that the molten shell powder is evenly coated on the surface of the core powder, and using a coating powder collecting device to further dry, screen and plasma spheroidize the coated powder that flies out of the high-temperature flame flow and solidifies to form a semi-finished product, so as to obtain the target coated powder. The method has a simple process and high powder making efficiency. The prepared coated powder shell powder and core powder are evenly coated and have a good spherical structure. The powder is suitable for preparing multi-component thermal spray coatings.

[0062] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments.

[0063] Example 1

[0064] This embodiment provides a method for preparing thermal spray coating powder, comprising the following steps:

[0065] S1. Pretreatment of raw materials: Use a dry ball mill to ball mill the shell powder Si and core powder HfO2 respectively; first, the ball milling process for shell powder Si is as follows: use mixed ceramic balls with diameters of 3mm, 5mm, and 12mm (quantity ratio of 5:3:2) for ball milling, the ball-to-material ratio is 1.5:1, and the ball mill speed is 30r / min; the ball milling process for core powder HfO2 is as follows: use mixed ceramic balls with diameters of 3mm, 5mm, and 12mm (quantity ratio of 5:2:3) for ball milling, the ball-to-material ratio is 1.5:1, and the ball mill speed is 30r / min; after ball milling for 3h, take out a trace amount of shell powder Si and core powder HfO2, observe the powder particle size range, and stop ball milling when the shell powder Si particle size is 40-70μm and the core powder HfO2 particle size is 5-25μm.

[0066] The shell powder Si and core powder HfO2 after ball milling are dispersed respectively, wherein the shell powder Si dispersion process is: add the shell powder Si after ball milling into dispersant and deionized water and stir for 30 minutes, and the mass ratio of dispersant: powder: deionized water is 1:90:80; the core powder HfO2 dispersion process is: add the core powder HfO2 after ball milling into dispersant and deionized water and stir for 30 minutes, and the mass ratio of dispersant: powder: deionized water is 1:90:80; the above dispersants are all non-ionic dispersants polyethylene glycol; then, the shell powder Si and core powder HfO2 after dispersion are respectively put into a drying oven, dried at a temperature of 65°C for 3 hours, and the powder of the desired particle size is sieved through a sieve, wherein the sieved core powder HfO2 has a particle size of 5-20μm, and the sieved shell powder Si has a particle size of 40-60μm.

[0067] S2. Preparation of semi-finished coated powder: The shell powder Si obtained in step S1 is fed into the shell powder melting system 2, and the molten shell powder is sprayed out by the high-temperature flame flow. At the same time, the core powder HfO2 is passed through the core powder conveying system, and the core powder HfO2 is vertically fed into the high-temperature flame flow containing molten shell powder at a pressure of 3 bar and a distance of 40 mm. The molten shell powder Si is evenly coated on the surface of the core powder HfO2, flies out of the high-temperature flame flow and solidifies to form a semi-finished Si-HfO2 coated powder.

[0068] S3. Pretreatment of semi-finished coated powder: The semi-finished coated powder obtained in step S2 is collected by the coated powder collection system 3, and the powder with a particle size less than or equal to the maximum particle size of the core powder HfO2 of 20μm is uncoated powder. The powder with a particle size larger than the particle size range of the core powder HfO2 is sieved out through a sieve, that is, the powder with a particle size larger than the maximum particle size of the core powder HfO2 is sieved out through the filter 32 and will remain on the surface of the filter 32. The mesh size of the filter 32 should be slightly larger than 20μm. The powder retained on the surface of the filter 32 is put into a drying oven and dried at 120°C for 2h to obtain Si-HfO2 coated powder.

[0069] S4. Coating powder shaping treatment: The coating powder obtained in step S3 is placed in a plasma spraying device for plasma spheroidization treatment, that is, the coating powder is sprayed into a water tank filled with pure aqueous solution, the coating powder sunk to the bottom of the water tank is drained, and then placed in a drying oven for drying to collect the target Si-HfO2 coating powder.

[0070] The spraying parameters are: argon: 20L / min, hydrogen: 10L / min, powder feeding rate: 10g / min, spraying distance: 80mm, current: 450A, carrier gas: 18L / min; drying parameters are: temperature: 65℃, drying time: 3h.

[0071] After testing, the target Si-HfO2 coated powder obtained has high sphericity and good fluidity. The prepared coated powder has a fluidity of 35s / 50g and a bulk density of 2.3g / cm 3 . Due to the participation of inert gas in the powder preparation process, the obtained coated powder has a low degree of oxidation and an oxygen content of 0.18%. Using Si-HfO2 coated powder, a thermal spraying process was used to prepare an intermediate bonding layer of the functional coating on the surface of the ceramic-based composite material. The bonding strength of the Si-HfO2 bonding layer is 14MPa, which is about 40% higher than the bonding strength of the pure Si bonding layer of 10MPa. The maximum temperature resistance of the Si-HfO2 bonding layer is 1430℃, which is about 5.9% higher than the temperature resistance of the pure Si bonding layer of 1350℃.

[0072] The powder flowability test is carried out in accordance with the following standards: GB / T 39696-2020 "Standard Funnel Method for Determination of Flowability of Fine Ceramic Powders";

[0073] The bulk density of powders is determined in accordance with ISO 23145-1:2007 "Determination of density of advanced ceramic powders - Part 2: Bulk density";

[0074] The coating bonding strength performance test standard is: GB / T 8642-2002: "Determination of tensile bonding strength of thermal spraying".

[0075] Example 2

[0076] This embodiment provides a method for preparing thermal spray coating powder, comprising the following steps:

[0077] S1. Pretreatment of raw materials: Use a dry ball mill to ball mill the shell powder SiO2 and the core powder MgO respectively; first, the ball milling process for the shell powder SiO2 is: use mixed ceramic balls with diameters of 5mm, 10mm, and 15mm (quantity ratio of 5:3:2) for ball milling, the ball-to-material ratio is 2.2:1, and the ball mill speed is 55r / min; the ball milling process for the core powder MgO is: use mixed ceramic balls with diameters of 5mm, 10mm, and 15mm (quantity ratio of 5:2:3) for ball milling, the ball-to-material ratio is 3:1, and the ball mill speed is 60r / min; after ball milling for 3h, take out a trace amount of shell powder SiO2 and core powder MgO, observe the powder particle size range, and stop ball milling when the shell powder SiO2 particle size is 50-80μm and the core powder MgO particle size is 10-30μm.

[0078] The shell powder SiO2 and core powder MgO after ball milling are dispersed respectively, wherein the shell powder SiO2 dispersion process is: add the shell powder SiO2 after ball milling into dispersant and deionized water and stir for 40 minutes, and the mass ratio of dispersant: powder: deionized water is 1:95:105; the core powder MgO dispersion process is: add the core powder MgO after ball milling into dispersant and deionized water and stir for 40 minutes, and the mass ratio of dispersant: powder: deionized water is 1:100:110; the above dispersants are all non-ionic dispersants polyethylene glycol; then, the shell powder SiO2 and core powder MgO after dispersion are respectively put into a drying oven, dried at 75°C for 2.5h, and the powder of the required particle size is sieved through a sieve, wherein the sieved core powder MgO has a particle size of 10-25μm, and the sieved shell powder SiO2 has a particle size of 40-70μm.

[0079] S2. Preparation of semi-finished coated powder: The shell powder SiO2 obtained in step S1 is fed into the shell powder melting system 2, and the molten shell powder is sprayed out through the high-temperature flame flow. At the same time, the core powder MgO is passed through the core powder conveying system, and the core powder MgO is vertically fed into the high-temperature flame flow containing molten shell powder at a pressure of 6.5 bar and a distance of 145 mm. The molten shell powder SiO2 is evenly coated on the surface of the core powder MgO, flies out of the high-temperature flame flow and solidifies to form a semi-finished SiO2-MgO coated powder.

[0080] S3. Pretreatment of semi-finished coated powder: The semi-finished coated powder obtained in step S2 is collected by the coated powder collection system 3, and the powder with a particle size less than or equal to the maximum particle size of the core powder MgO of 25 μm is uncoated powder. The powder with a particle size larger than the particle size range of the core powder MgO is sieved out through a sieve, that is, the powder with a particle size larger than the maximum particle size of the core powder MgO is sieved out through the filter 32 and will remain on the surface of the filter 32. The mesh size of the filter 32 should be slightly larger than 25 μm. The powder retained on the surface of the filter 32 is put into a drying oven and dried at 120°C for 2 hours to obtain SiO2-MgO coated powder.

[0081] S4. Coating powder shaping treatment: The coating powder obtained in step S3 is placed in a plasma spraying device for plasma spheroidization treatment, that is, the coating powder is sprayed into a water tank filled with pure aqueous solution, the coating powder sunk to the bottom of the water tank is drained, placed in a drying oven, and dried to obtain the target SiO2-MgO coated powder.

[0082] The spraying parameters are: nitrogen: 35L / min, hydrogen: 30L / min, powder feeding rate: 50g / min, spraying distance: 150mm, current: 500A, carrier gas: 15L / min; drying parameters are: temperature: 75℃, drying time: 2.5h.

[0083] After testing, the target SiO2-MgO coated powder obtained has high sphericity and good fluidity. The prepared coated powder has a fluidity of 46s / 50g and a bulk density of 3.4g / cm 3 . Due to the participation of inert gas in the powder preparation process, the oxidation degree of the coated powder is low, and the oxygen content is 0.25%. Using SiO2-MgO coated powder, a low-density intermediate layer of functional heat-resistant coating is prepared on the surface of the material by thermal spraying process. SiO2-MgO reduces the weight of the heat-resistant coating and reduces the surface density by 15%.

[0084] The powder flowability test is carried out in accordance with the following standards: GB / T 39696-2020 "Standard Funnel Method for Determination of Flowability of Fine Ceramic Powders";

[0085] The bulk density of powders is determined in accordance with ISO 23145-1:2007 "Advanced ceramics - Determination of density of ceramic powders".

[0086] Example 3

[0087] This embodiment provides a method for preparing thermal spray coating powder, comprising the following steps:

[0088] S1. Raw material pretreatment: Use a dry ball mill to ball mill the shell powder SiO2 and core powder Y2O3 respectively; first, the ball milling process for shell powder SiO2 is as follows: use mixed ceramic balls with diameters of 10mm, 15mm, and 20mm (quantity ratio of 5:3:2) for ball milling, the ball-to-material ratio is 6:1, and the ball mill speed is 90r / min; the ball milling process for core powder Y2O3 is as follows: use mixed ceramic balls with diameters of 10mm, 15mm, and 20mm (quantity ratio of 5:2:3) for ball milling, the ball-to-material ratio is 7:1, and the ball mill speed is 90r / min; after ball milling for 3h, take out a trace amount of shell powder SiO2 and core powder Y2O3, observe the powder particle size range, and stop ball milling when the shell powder SiO2 particle size is between 90 and 120μm and the core powder Y2O3 particle size is between 20 and 45μm.

[0089] The shell powder SiO2 and core powder Y2O3 after ball milling are dispersed respectively, wherein the shell powder SiO2 dispersion process is: add the shell powder SiO2 after ball milling into dispersant and deionized water and stir for 60 minutes, the mass ratio of dispersant: powder: deionized water is 1:120:110; the core powder Y2O3 dispersion process is: add the core powder Y2O3 after ball milling into dispersant and deionized water and stir for 60 minutes, the mass ratio of dispersant: powder: deionized water is 1:120:105; the above dispersants are all ionic dispersants triethanolamine; then, the shell powder SiO2 and core powder Y2O3 after dispersion are respectively put into a drying oven, dried at 90°C for 2h, and the powder of the desired particle size is sieved through a sieve, wherein the sieved core powder Y2O3 has a particle size of 30-45μm, and the sieved shell powder SiO2 has a particle size of 100-120μm.

[0090] S2. Preparation of semi-finished coated powder: The shell powder SiO2 obtained in step S1 is fed into the shell powder melting system 2, and the molten shell powder is sprayed out by the high-temperature flame flow. At the same time, the core powder MgO is passed through the core powder conveying system, and the core powder MgO is vertically fed into the high-temperature flame flow containing molten shell powder at a pressure of 9 bar and a distance of 200 mm. The molten shell powder SiO2 is evenly coated on the surface of the core powder Y2O3, flies out of the high-temperature flame flow and solidifies to form a semi-finished SiO2-Y2O3 coated powder.

[0091] S3. Pretreatment of semi-finished coated powder: The semi-finished coated powder obtained in step S2 is collected by the coated powder collection system 3, and the powder with a particle size less than or equal to the maximum particle size of the core powder Y2O3 of 45μm is uncoated powder. The powder with a particle size larger than the particle size range of the core powder Y2O3 is sieved out through a sieve, that is, the powder with a particle size larger than the maximum particle size of the core powder Y2O3 is sieved out through the filter 32 and will remain on the surface of the filter 32. The mesh size of the filter 32 should be slightly larger than 45μm. The powder retained on the surface of the filter 32 is put into a drying oven and dried at 120°C for 2h to obtain SiO2-Y2O3 coated powder.

[0092] S4. Coating powder shaping treatment: The coating powder obtained in step S3 is placed in a plasma spraying device for plasma spheroidization treatment, that is, the coating powder is sprayed into a water tank filled with pure aqueous solution, the coating powder that sinks to the bottom of the water tank is drained, placed in a drying oven, and then dried and collected to obtain the target SiO2-Y2O3 coated powder.

[0093] The spraying parameters are: argon: 80L / min, hydrogen: 40L / min, powder feeding rate: 100g / min, spraying distance: 260mm, current: 550A, carrier gas: 12L / min; drying parameters are: temperature: 90℃, drying time: 2h.

[0094] After testing, the target SiO2-Y2O3 coated powder obtained has high sphericity and good fluidity. The prepared coated powder has a fluidity of 78s / 50g and a bulk density of 4.0g / cm 3 . Due to the participation of inert gas in the powder preparation process, the oxidation degree of the coated powder is low, and the oxygen content is 0.22%. Using SiO2-Y2O3 coated powder, a low-density intermediate layer of functional heat-resistant coating is prepared on the surface of the material by thermal spraying process. SiO2-Y2O3 reduces the weight of the heat-resistant coating and reduces the surface density by 13%.

[0095] The powder flowability test is carried out in accordance with the following standards: GB / T 39696-2020 "Standard Funnel Method for Determination of Flowability of Fine Ceramic Powders";

[0096] The bulk density of powders is determined in accordance with ISO 23145-1:2007 "Advanced ceramics - Determination of density of ceramic powders".

[0097] The above description is only a specific embodiment of the present invention, so that those skilled in the art can understand or implement the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention.

[0098] It should be understood that the present invention is not limited to what has been described above and that various modifications and changes may be made without departing from its scope. The scope of the present invention is limited only by the appended claims.

Claims

1. A device for preparing thermal spray coating powder, characterized in that: include: The shell powder melting system (2) is used to heat the shell powder to a molten state and eject it with a high-temperature flame flow. The core powder material conveying system (1) is used to convey the core powder into the high-temperature flame flow of the shell powder in a molten state, so that the molten shell powder is coated on the surface of the core powder. The coating powder collection system (3) is used to collect the semi-finished coating powder that flies out of the high-temperature flame flow and solidifies, and to screen the collected semi-finished coating powder.

2. The device for preparing thermal spray coating powder according to claim 1, characterized in that: The core powder material conveying system (1) comprises an air compressor (11), the air compressor (11) is connected to a fluidized bed (14) via a core powder air pipe (13), a powder outlet end of the fluidized bed (14) is connected to a core powder delivery pipe (15), and an outlet end of the core powder delivery pipe (15) is connected to a clustering device (16). A pressure gauge (12) is also connected between the air compressor (11) and the core powder air pipe (13). The fluidized bed (14) contains core powder, and the powder outlet is arranged at the upper end of the fluidized bed (14).

3. The device for preparing thermal spray coating powder according to claim 1, characterized in that: The shell powder melting system (2) comprises a copper frame arranged in the middle, one end of the copper frame is connected to an inert gas high-pressure gas cylinder (201), an active gas high-pressure gas cylinder (202), a barometer (203), an air pipe (204), an air compressor (205), a shell powder feeding tank (206), a shell powder air pipe (207) and a power supply (208), the other end of the copper frame is connected to a cathode head (209) and an anode head (210), and a high-voltage radio frequency generator (217) is installed in the copper frame. The inert gas high-pressure gas cylinder (201) and the active gas high-pressure gas cylinder (202) are connected in parallel to the air pipe (204), and a pressure gauge (203) is also provided on the air pipe (204). One end of the shell powder feeding tank (206) is connected to the air compressor (205), and the other end is connected to the shell powder air pipe (207). The air pipe (204) and the shell powder air pipe (207) are connected to the air inlet pipe (215) in the copper frame. The air inlet pipe (215) passes through the copper frame and is connected to the powder outlet provided on the cathode head (209). The cathode head (209) and the anode head (210) are both mounted on an insulator seat (216). The negative electrode of the power source (208) enters from one end of the copper frame through a cable (211), is sequentially connected to a high-voltage radio frequency generator (217) and then connected to the cathode head (209). One end of the anode head (210) is connected to the positive electrode of the power source (208) through a cable (211). The cavity with an open end surrounded by the anode head (210) and the cathode head (209) is a discharge chamber (214). The high-voltage radio frequency generator (217) increases the voltage in the discharge chamber (214) exponentially to generate a plasma arc in the discharge chamber (214). The air compressor (205) is connected to the shell powder feeding tank (206) through an air pipe, and powder is fed into the plasma arc through the shell powder air pipe (207) by conveying carrier gas to form a molten powder jet. A water inlet (212) and a water outlet (213) are connected to the outside of the copper frame. Flowing water enters from the water inlet (212), is circulated and cooled in the outer sleeve of the copper frame, and is then discharged from the water outlet (213).

4. The device for preparing thermal spray coating powder according to claim 3, characterized in that: The gas in the inert gas high-pressure gas cylinder (201) is any one of nitrogen and argon, and the gas in the active gas high-pressure gas cylinder (202) is hydrogen. The cathode head (209) is made of graphite or silver-based alloy. The material of the insulator seat (216) is aluminum oxide or silicon nitride.

5. The device for preparing thermal spray coating powder according to claim 1, characterized in that: The coated powder collection system (3) comprises a powder collection trough (31), water is stored inside the powder collection trough (31), a filter screen (32) is installed inside the powder collection trough (31), and a drainage port (33) is opened at the bottom of the powder collection trough (31).

6. The device for preparing thermal spray coating powder according to claim 5, characterized in that: The mesh size of the filter (32) is 15 to 150 μm.

7. A method for preparing thermal spray coating powder, characterized in that: The device for preparing thermal spray coating powder according to any one of claims 1 to 6 comprises the following steps: S1. Raw material pretreatment: The shell powder and the core powder are ball-milled, respectively, and the shell powder and the core powder after ball milling are dispersed, and then, the shell powder and the core powder of the desired particle size are obtained by drying and sieving; S2. Preparation of semi-finished coated powder: The shell powder and core powder obtained in step S1 are respectively placed in the shell powder melting system (2) and the core powder conveying system (1), the shell powder in a molten state is sprayed out through the high-temperature flame flow, and the core powder is vertically fed into the high-temperature flame flow containing molten shell powder at a certain pressure and distance, the molten shell powder is coated on the surface of the core powder, and flies out of the high-temperature flame flow to solidify to form a semi-finished coated powder; S3. Pretreatment of the semi-finished coated powder: The semi-finished coated powder obtained in step S2 is collected by the coated powder collection system (3) and then sieved and dried to obtain the coated powder; S4. Coating powder shaping treatment: The coating powder obtained in step S3 is subjected to plasma spheroidization treatment by plasma spraying equipment, and then dried to obtain the target coating powder.

8. The method for preparing thermal spray coating powder according to claim 7, characterized in that: The specific steps of the ball milling treatment in step S1 are: using a dry ball mill, using ceramic balls with a diameter of 3 to 20 mm to ball mill the raw materials, with a ball-to-material ratio of 1.5 to 7:1, and a ball mill speed of 30 to 90 r / min, The specific steps of the dispersion treatment are: adding the ball-milled powder to a dispersant and deionized water and stirring for 30 to 60 minutes, wherein the mass ratio of the dispersant: the powder: the deionized water is 1: (90 to 120): (80 to 110), the powder is shell powder or core powder, and the dispersant is an ionic or non-ionic dispersant. The specific steps of the drying and screening treatment are: placing the dispersed powder into a drying oven, drying at a temperature of 65-90°C for 2-3 hours, and screening out the powder of the desired particle size through a sieve, wherein the particle size of the screened core powder is 5-45 μm, and the particle size of the screened shell powder is 40-120 μm.

9. The method for preparing thermal spray coating powder according to claim 7, characterized in that: In step S2, the core powder is vertically fed into a high-temperature flame flow containing molten shell powder at a pressure of 3 to 9 bar and a distance of 40 to 200 mm. In step S3, the specific steps of collecting the semi-finished coated powder by the coated powder collection system (3), drying it and sieving it to obtain the coated powder are as follows: sieving the powder with a particle size larger than the maximum particle size of the core powder through the filter screen (32) and retaining it on the surface of the filter screen (32), placing the powder retained on the surface of the filter screen (32) in a drying oven, and drying it at 120° C. for 2 hours to obtain the coated powder.

10. The method for preparing thermal spray coating powder according to claim 7, characterized in that: The specific steps of shaping the coated powder in step S4 are: putting the coated powder obtained in step S3 into a plasma spraying device, spraying the coated powder into a water tank filled with a pure aqueous solution, draining the coated powder at the bottom of the water tank, putting it into a drying oven, drying it, and collecting the target coated powder. Spraying parameters are: argon: 20-150L / min, nitrogen: 20-150L / min, hydrogen: 10-40L / min, powder feeding rate: 15-100g / min, spraying distance: 80-260mm, current: 450-550A, carrier gas: 12-18L / min; Drying parameters are: temperature: 65~90℃, drying time: 2-3h.

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