Disturbance-free laminar flow plasma spray powder feeding device and system

Abstract

The application provides a disturbance-free laminar flow plasma spraying powder feeding device and system, which is applied to a laminar flow plasma spraying system, a jet flow area is formed in the center of the device; the device comprises a fixed component, a distribution component and a mixing component which are arranged in axial overlap, and a converging component which is arranged in radial overlap with the mixing component, the converging component is communicated with the jet flow area; wherein a plurality of powder feeding holes are respectively formed in the fixed component, the distribution component, the mixing component and the converging component, and all the powder feeding holes are communicated through a shunt channel; wherein the carrier gas flowing into the powder feeding holes on the corresponding components flows through the shunt channel, and flows radially into the jet flow area after speed reduction through the shunt channel, so as to prevent the carrier gas from disturbing the laminar flow plasma jet in the jet flow area. Through the powder feeding device provided by the application, the problem that the laminar flow plasma jet is easily disturbed by the carrier gas and causes the jet flow to be transformed into turbulent flow is solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of plasma spraying, in particular to a disturbance-free laminar flow plasma spraying powder feeding device and system. BACKGROUND

[0002] Plasma spraying, as a typical thermal spraying technology, uses high-temperature and high-speed plasma jet to heat the injected powder material to a molten or semi-molten state, and accelerates it to impact the substrate or the surface of the previously deposited coating. The impacted particles quickly flow laterally and spread, and quickly cool and solidify to connect with the substrate or the coating. After a large number of particles are accumulated, a coating is finally formed. The coating can provide the substrate surface with properties such as electrical conductivity, wear resistance, high-temperature resistance and oxidation resistance, and is currently widely used in fields such as metallurgy, energy, petrochemical industry, marine engineering, aerospace and weapon equipment, and is one of the important processes for surface protection and strengthening.

[0003] Laminar flow plasma spraying is a way of spraying using laminar flow plasma jet as a heat source. The laminar flow plasma jet is a laminar flow state plasma jet, which has a longer jet length and a lower energy gradient than the turbulent flow plasma jet. When using laminar flow plasma spraying, the jet velocity is lower and the high-temperature region is longer, which can promote the powder particles to stay in the jet for a longer time for further heating, and has good development potential.

[0004] Currently, when using laminar flow plasma spraying, the main powder feeding method of plasma spraying is to use high-pressure carrier gas to blow out the powder particles. This method usually has a flow speed of more than 10 m / s, and the laminar flow plasma jet is easily disturbed radially and turns into a turbulent flow plasma jet, losing the characteristic of longer heating time of the laminar flow plasma jet for powder particles. Therefore, the existing powder feeding mechanism cannot further improve the temperature of the powder particles, and even cannot effectively deposit into a coating, which limits the development of laminar flow plasma spraying. SUMMARY

[0005] In view of the above problems, one of the purposes of the present application is to provide a disturbance-free laminar flow plasma spraying powder feeding device, which solves the problem of laminar flow plasma spraying powder feeding, can feed ceramic powder particles into the jet without disturbing the laminar flow plasma jet, and realizes effective deposition of the coating and atmospheric laminar flow plasma spraying-physical vapor deposition process.

[0006] The technical scheme of the present application is:

[0007] A disturbance-free laminar flow plasma spraying powder feeding device is applied to a laminar flow plasma spraying system. A jet flow area is formed through the center of the device, and the jet flow area is used to allow the laminar flow plasma jet to pass through. The device comprises:

[0008] The fixed part, the distribution part and the mixing part are arranged axially overlapped, and the confluence part is arranged radially overlapped with the mixing part, and the confluence part is communicated with the jet flow area; wherein,

[0009] A plurality of powder inlet holes are respectively arranged on the fixed part, the distribution part, the mixing part and the confluence part, and all the powder inlet holes are communicated through the shunt channel, and the shunt channel is configured to change the flow path of the carrier gas; wherein,

[0010] The carrier gas flowing from the powder inlet hole on the corresponding part flows through the shunt channel, and after the speed is reduced by the shunt of the shunt channel, it flows radially into the jet flow area to prevent the carrier gas from disturbing the laminar plasma jet in the jet flow area.

[0011] As one of the preferred solutions, the shunt channel comprises:

[0012] The first distribution groove is arranged on the distribution part, and is respectively communicated with the first powder inlet hole on the fixed part and the second powder inlet hole of itself;

[0013] The second distribution groove is arranged on the mixing part, and is respectively communicated with the second powder inlet hole and the third powder inlet hole of itself;

[0014] The third distribution assembly is arranged on the side of the mixing part opposite to the second distribution groove, and is respectively communicated with the third powder inlet hole and the fourth powder inlet hole on the mixing part;

[0015] Wherein, the carrier gas input from the first powder inlet hole into the first distribution groove is reduced in speed by the first shunt, then flows into the second distribution groove through the second powder inlet hole and is reduced in speed by the second shunt, then flows into the third distribution assembly through the third powder inlet hole and is reduced in speed by the third shunt, and then flows into the jet flow area through the fourth powder inlet hole.

[0016] As one of the preferred solutions, the third distribution assembly comprises a plurality of guide flow channels and a mixing flow channel, each guide flow channel is respectively communicated with each third powder inlet hole and the mixing flow channel; wherein,

[0017] At least part of the confluence part in the axial direction is installed in the mixing flow channel, and the fourth powder inlet hole is located in the mixing flow channel.

[0018] As one of the preferred solutions, each guide flow channel extends from the corresponding third powder inlet hole to the midpoint of the line connecting two powder inlet holes in the direction of the adjacent third powder inlet hole in clockwise or counterclockwise direction.

[0019] As one of the preferred solutions, the extension end of each of the guide flow channels is tangent to the edge of the mixing flow channel.

[0020] As one of the preferred solutions, the number of the first-stage powder inlet holes, the second-stage powder inlet holes, the third-stage powder inlet holes and the fourth-stage powder inlet holes gradually increases; and,

[0021] The positions of the adjacent and connected powder inlet holes other than the fourth-stage powder inlet holes are staggered, and the axial projection of the upper-stage powder inlet hole is located on the symmetry axis formed by the lower-stage powder inlet hole.

[0022] The fourth-stage powder inlet hole is configured to be oriented at an angle.

[0023] As one of the preferred solutions, the device further comprises a water cooling component and a shell component, the water cooling component is connected with the mixing component and the shell component in the axial direction respectively; wherein,

[0024] The water cooling component and the shell component enclose a water cooling chamber, and the water cooling chamber is used to accommodate a cooling medium.

[0025] As one of the preferred solutions, a guide baffle is arranged on the shell component, and the guide baffle extends downwardly and obliquely in the direction close to the jet flow area.

[0026] As one of the preferred solutions, the device further comprises a sealing part, the sealing part comprises a plurality of sealing grooves and a plurality of sealing rings, and each of the sealing rings is embedded into each of the sealing grooves.

[0027] At least a first part of the sealing grooves are arranged at the positions close to the shunt passage between the two components adjacent in position respectively.

[0028] At least a second part of the sealing grooves are arranged at the positions close to the water cooling chamber.

[0029] The sum of the first part and the second part is not greater than the number of all the sealing grooves.

[0030] Compared with the prior art, the present application has the following advantages:

[0031] The application provides a disturbance-free laminar flow plasma spraying powder feeding device, which is applied to a laminar flow plasma spraying system, a jet flow area is formed in the center of the device, and the jet flow area is used for allowing laminar flow plasma jet to pass through; the device comprises: a fixed component, a distribution component and a mixing component which are arranged in axial overlap, and a confluence component which is arranged in radial overlap with the mixing component and is in communication with the jet flow area; wherein a plurality of powder feeding holes are formed in the fixed component, the distribution component, the mixing component and the confluence component respectively, all the powder feeding holes are in communication through a shunt channel, and the shunt channel is configured to change the flow path of the carrier gas; wherein the carrier gas flowing into the powder feeding holes on the corresponding components flows through the shunt channel, and flows radially into the jet flow area after speed reduction through the shunt of the shunt channel, so as to prevent the carrier gas from disturbing the laminar flow plasma jet in the jet flow area.

[0032] By adopting the technical scheme of the application, based on the stable natural entrainment phenomenon of laminar flow plasma, the natural entrainment is simulated, the path of the carrier gas (powder feeding gas carrying powder) flow is arranged, the powder is fed into the powder feeding holes on the fixed component, and then sequentially passes through the distribution component, the mixing component and the confluence component to enter the jet flow area. In the flow process of the carrier gas, the shunt channel uniformly distributes and flows the carrier gas, improves the uniformity of the powder and slows down the flow speed of the powder, so as to simulate the natural entrainment of the jet flow by using the carrier gas, and realize zero disturbance powder feeding. Compared with the existing traditional high-carrier-gas powder feeding technology, the disturbance of the carrier gas on the jet flow is greatly reduced, the heating efficiency of the plasma jet on the powder is improved, the powder is heated to melting or even gasification, and the plasma spraying atmospheric physical vapor deposition process is realized.

[0033] The second aspect of the application also provides a laminar flow plasma spraying system which is provided with the disturbance-free laminar flow plasma spraying powder feeding device provided in the first aspect of the application.

[0034] The system has the same advantages as the disturbance-free laminar flow plasma spraying powder feeding device described above with respect to the prior art, and will not be described here. BRIEF DESCRIPTION OF DRAWINGS

[0035] In order to more clearly illustrate the technical scheme of the application, the drawings required to be used in the description of the application will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0036] Figure 1 It is the overall structure assembly diagram of the disturbance-free laminar flow plasma spraying powder feeding device described in an embodiment of the application;

[0037] Figure 2is a structural assembly diagram of the fixed component according to an embodiment of the present application;

[0038] Figure 3 is a structural assembly diagram of the distribution component according to an embodiment of the present application;

[0039] Figure 4 is a structural assembly diagram of the mixing component according to an embodiment of the present application;

[0040] Figure 5 is a structural assembly diagram of the confluence component according to an embodiment of the present application;

[0041] Figure 6 is a structural assembly diagram of the water cooling component according to an embodiment of the present application;

[0042] Figure 7 is a structural assembly diagram of the shell component according to an embodiment of the present application;

[0043] Figure 8 is a temperature distribution statistical diagram of the outlet of the plasma torch under different carrier gas flow rates according to an embodiment of the present application;

[0044] Figure 9 is a temperature distribution and end turbulent intensity distribution cloud diagram of the plasma jet outlet when the carrier gas flow rate is 4 L·min -1

[0045] Figure 10 is a schematic diagram of the appearance of the laminar plasma jet before and after powder feeding and the spraying process according to an embodiment of the present application;

[0046] Figure 11 is a structural appearance micrograph of the coating formed by the laminar plasma spraying according to an embodiment of the present application.

[0047] Explanation of reference signs:

[0048] ​1, fixed parts; 101, primary positioning hole; 102, primary powder inlet hole; 103, first threaded fixing hole; 2, distribution parts; 201, secondary positioning hole; 202, secondary powder inlet hole; 203, primary distribution groove; 204, first sealing groove; 205, second sealing groove; 3, mixing parts; 301, tertiary positioning hole; 302, tertiary powder inlet hole; 303, secondary distribution groove; 304, guide flow channel; 305, mixing flow channel; 306, groove; 307, third sealing groove; 308, fourth sealing groove; 309, fifth sealing groove; 4, flow convergence parts; 401, quaternary powder inlet hole; 402, sixth sealing groove; 5, water cooling parts; 501, quaternary positioning hole; 502, second threaded fixing hole; 503, seventh sealing groove; 504, eighth sealing groove; 6, shell parts; 601, quinary positioning hole; 602, third threaded fixing hole; 603, water outlet; 604, guide baffle; 7, nozzle sleeve; 8, jet zone; 9, water cooling chamber. DETAILED DESCRIPTION

[0049] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are some of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0050] In the related art, according to the background described above, the flow characteristics of the laminar plasma jet have many characteristics such as long jet length, stable direction, and uniform heat source, which can improve the heating uniformity of the powder particles and the deposition effect. If the laminar plasma jet is transformed into a turbulent plasma jet, the jet length will be shortened, the flow direction will be disturbed, and the plasma gas will be unevenly distributed, thereby shortening the flight time of the powder particles in the plasma jet, increasing the flight speed, greatly shortening the heating time, reducing the surface temperature, and further causing the powder particles to not be completely melted or reacted when reaching the substrate surface, resulting in poor quality or failure to form a coating.

[0051] Among them, the powder (such as small particles of metal, ceramic, carbide, nitride or other materials) needs to be sent into the plasma jet by the powder feeding mechanism to collide with active particles (such as electrons, ions, radicals, etc.) in the plasma to be heated to a molten or gaseous state. Since the powder needs to be sent to the central region of the plasma jet, the powder is always sent from the radial direction of the plasma jet. If the powder feeding speed is too large, it will change the flow state of the laminar plasma jet, and if the feeding speed is too small, the powder cannot be output from the powder feeding device.

[0052] In the related art, a powder feeding device suitable for super-high-speed laser cladding is proposed, which aims to feed powder to the laser focal plane to achieve effective concentrated heating of powder particles and improve powder utilization rate. However, laser cladding is mainly used for the preparation of metal coatings, and the metal powder adopted by the powder feeding device has good flowability and large inertia. In order to make the metal powder have a high initial speed, the spacing of the powder feeding channel of the powder feeding device is designed to be narrower, so that:

[0053] When a low-speed carrier gas flow is used, the jet can be prevented from being disturbed radially, but the flow rate of non-metallic powders such as ceramic powders is slow, and the powder feeding channel is blocked, which cannot be smoothly fed into the plasma jet;

[0054] When the carrier gas is increased to a sufficient amount to ensure that the non-metallic powder can be fed out, the outlet of the powder feeding device will have a high speed, which will cause the laminar plasma jet to be turbulent, the heating zone to be shortened, and the particles to be effectively heated.

[0055] Therefore, the powder feeding device needs to ensure that the powder particles can pass through the basic outlet radius with a higher carrier gas flow to ensure that the powder particles can be fed out at a faster speed and then converge on the focal plane. For the laminar plasma spraying process, this powder feeding method is not suitable for ceramic powders with poor flowability, and the function is single, which limits the application range of laser cladding technology, and cannot be used to prepare ceramic coatings, non-metallic coatings or other composite coatings with different organizational structures and properties.

[0056] Therefore, with reference to Figures 1-4 ; Figure 1 is the overall structure assembly drawing of the interference-free laminar plasma spraying powder feeding device shown in the present application; Figure 2 is the structure assembly drawing of the fixed part 1 shown in the present application; Figure 3 is the structure assembly drawing of the distribution part 2 shown in the present application; Figure 4 is the structure assembly drawing of the mixing part 3 shown in the present application; Figure 5 is the structure assembly drawing of the converging part 4 shown in the present application. The structure assembly drawing is considered as a collection of perspective view, top view and sectional view in the present application.

[0057] Please refer to Figure 1The application provides a disturbance-free laminar flow plasma spraying powder feeding device, which is characterized by being applied to a laminar flow plasma spraying system, a jet flow area 8 is formed in the center of the device, and the jet flow area 8 is used for allowing laminar flow plasma jet flow to pass through; the device comprises: a fixed component 1, a distribution component 2 and a mixing component 3 which are arranged in axial overlap, and a confluence component 4 which is arranged in radial overlap with the mixing component 3 and is in communication with the jet flow area 8; wherein a plurality of powder inlet holes are respectively formed in the fixed component 1, the distribution component 2, the mixing component 3 and the confluence component 4, and all the powder inlet holes are in communication through a shunt channel, and the shunt channel is configured to change the flow path of the carrier gas; wherein the carrier gas flowing into the powder inlet holes on the corresponding components flows through the shunt channel, and after being slowed down by shunting of the shunt channel, flows radially into the jet flow area 8, so as to prevent the carrier gas from disturbing the laminar flow plasma jet flow in the jet flow area 8.

[0058] Specifically, the powder feeding device in the embodiment of the application is particularly suitable for a laminar flow plasma spraying system, which generally comprises a workbench, a plasma spraying gun, a gas supply device, a control system and a powder supply device and the like. The center of the device is formed with a jet flow area 8, that is, the jet flow area 8 is formed by the central portions of the four components, i.e., the fixed component 1, the distribution component 2, the mixing component 3 and the confluence component 4, which are all provided with through holes and are in communication with each other. The entire powder feeding device is cooperated with and fixed to the plasma spraying gun through a plurality of first screw fixing holes 103 on the fixed component 1 which are directed to the center of the circle.

[0059] Specifically, the fixed component 1, the distribution component 2 and the mixing component 3 are all not higher than the plane where the nozzle is located, and the through holes provided in the three components are in communication to form a nozzle sleeve 7 which wraps the front end of the plasma spraying gun. There is an electric arc in the plasma spraying gun, and the inert gas (such as argon, nitrogen, hydrogen and the like) is ionized into high-temperature and high-pressure plasma jet flow by electric current, and the plasma jet flow is sprayed outward through the nozzle to form a plasma jet flow.

[0060] The powder feeding device is of a split structure, and the axial overlap arrangement can be understood as, when the device is vertically placed, the fixed component 1, the distribution component 2 and the mixing component 3 are sequentially arranged from top to bottom (as shown in Figure 1 Fig. 1). Similarly, when the device is horizontally placed, the axial overlap arrangement means that the fixed component 1, the distribution component 2 and the mixing component 3 are sequentially arranged from left to right. The radial overlap arrangement can be understood as the mixing component 3 and the confluence component 4 are sequentially arranged from outside to inside.

[0061] In this embodiment, the four components are all of annular structure and coaxially arranged, wherein the inner and outer diameters of the fixed component 1, the distribution component 2 and the mixing component 3 are the same, the confluence component 4 is located on the inner side of the mixing component 3 and has the same inner diameter as the other components, and a straight cylinder jet flow area 8 is formed. Specifically, please continue to refer to Figure 2The fixed part 1 includes a cylindrical sleeve part and a flat part, the cylindrical sleeve part is provided with the first threaded fixing holes 103 mentioned above, the extension line of each first threaded fixing hole 103 passes through the center of the cylindrical sleeve part, which can be fixed with the mounting hole on the plasma torch through mechanical engagement, and keep the cylindrical sleeve part coaxial with the plasma torch anode and the outlet. The flat part is provided with at least one first powder inlet hole 102. The first powder inlet hole 102 is provided with a thread, which is a carrier gas inlet for connecting the threaded quick connector on the powder feeding pipe in the powder supply device.

[0062] In some embodiments, at least 3, preferably 4, first threaded fixing holes 103 are provided, and the powder feeding device is fixed with the plasma torch by sequentially passing 4 bolts through the first threaded fixing holes 103 and the mounting hole, so as to ensure that the powder feeding device can keep relatively stationary with the plasma torch.

[0063] It can be understood that the powder inlet holes are through holes penetrating through the corresponding parts, so that the four parts form an airflow circulation channel. The carrier gas is a mixture of compressed gas and powder particles, such as compressed helium, nitrogen or argon, which has sufficient gas velocity and power to push the powder particles from the powder supply system to the plasma jet area 8.

[0064] Specifically, please continue to refer to Figure 3 The distribution part 2 includes a plurality of second powder inlet holes 202 and a first distribution groove 203 in the flow distribution channel, the first distribution groove 203 is annular and coaxial with the whole part, the center radius between the inner and outer diameters is the same as the radius of the circle where the center of the first powder inlet hole 102 on the fixed part 1 is located, and the first powder inlet hole 102 can be covered inside it, and the second powder inlet hole 202 is located inside the first distribution groove 203, so that the carrier gas flows from the first powder inlet hole 102 into the first distribution groove 203, slows down through the flow distribution of the first distribution groove 203, and flows out of the distribution part 2 through the second powder inlet hole 202.

[0065] Please continue to refer to Figure 4 The mixing part 3 includes a plurality of third powder inlet holes 302 and a second distribution groove 303 in the flow distribution channel, the second distribution groove 303 is opposite to the position of the first distribution groove and has the same inner and outer diameters, and is arranged on the top surface of the mixing part 3 so that it can cover the second powder inlet hole 202 on the distribution part 2 above, and the third powder inlet hole 302 is located inside the second distribution groove 303, so that the carrier gas flowing out of the distribution part 2 flows to the second distribution groove 303, slows down through the flow distribution of the second distribution groove 303, and flows out of the mixing part 3 through the third powder inlet hole 302.

[0066] In some embodiments, the bottom surface of the mixing component 3 is provided with a three-stage distribution assembly and communicates with the outlet of the three-stage powder inlet hole 302, so that the carrier gas flowing out of the three-stage powder inlet hole 302 flows out of the mixing component 3 after being further divided and slowed down by the three-stage distribution assembly.

[0067] The converging component 4 is annular, and the middle and upper parts are arranged in the groove 306 opened in the mixing component 3, and the inner diameter thereof serves as the wall surface of the jet flow area 8, which includes a plurality of four-stage powder inlet holes 401 facing the jet flow area 8. The carrier gas flowing out of the three-stage distribution assembly flows into the jet flow area 8 through the four-stage powder inlet holes 401 and mixes with the laminar plasma jet.

[0068] In this way, based on the stable natural entrainment phenomenon of the laminar plasma, the powder is input from the first powder feeding hole of the fixed component 1, sequentially passes through the first-stage distribution groove 203 and the second-stage powder inlet hole 202 of the distribution component 2, the second-stage distribution groove 303, the third-stage powder inlet hole 302 and the three-stage distribution assembly of the mixing component 3, and the four-stage powder inlet hole 401 of the converging component 4 into the jet flow area 8, and in the flow process of the carrier gas, the carrier gas is uniformly distributed and flows through the multi-stage division of the division channel, which improves the uniformity of the powder and slows down the flow speed of the powder, so as to simulate the natural entrainment of the jet flow by using the carrier gas and realize zero disturbance powder feeding. Compared with the existing traditional high-carrier-gas powder feeding technology, this technology is suitable for inputting non-metallic powders such as ceramic powders, effectively inputs the powder into the plasma jet, greatly reduces the disturbance of the carrier gas to the jet flow, improves the heating efficiency of the plasma jet to the powder, and is beneficial to heating the powder to melting or even gasification, and realizes the process of plasma spraying and atmospheric physical vapor deposition.

[0069] In some embodiments, the number of powder inlet holes on each component can be the same or different; in some embodiments, the shape and size of the powder inlet holes on each component can be the same or different; in some embodiments, the shape and size of the first-stage distribution groove 203 and the second-stage distribution groove 303 can be the same or different.

[0070] In combination with the above embodiments, the number of the first-stage powder inlet hole 102, the second-stage powder inlet hole 202, the third-stage powder inlet hole 302 and the four-stage powder inlet hole 401 gradually increases; and the positions of the adjacent powder inlet holes are staggered, and the axial projection of the upper-stage powder inlet hole 102 is located on the symmetry axis formed by the lower-stage powder inlet hole 102; the four-stage powder inlet hole 401 is configured to be oriented at a certain angle.

[0071] In the embodiment, the first powder inlet hole 102 is arranged on the fixed part 1, the second powder inlet holes 202 are arranged inside the first powder distribution groove 203 of the distribution part 2, the two second powder inlet holes 202 are on the diameter of the distribution part 2 and the connecting line passes through the center of the distribution part 2, and the center of the first powder inlet hole 102 is on the perpendicular bisector of the connecting line of the two second powder inlet holes 202. The third powder inlet holes 302 are arranged in the second gas distribution groove of the mixing part 3, the connecting line of the two second powder inlet holes 202 is the symmetry axis of the square composed of the connecting lines of the four third powder inlet holes 302, and the second powder inlet hole 202 and the third powder inlet hole 302 are not coincident in position.

[0072] Therefore, along the direction of the carrier gas flow, the number of the multi-stage powder inlet holes is gradually added, and the powder inlet holes of the upper and lower stages are staggered, the number of the powder inlet holes is increased in the direction of the carrier gas flow, the gathering of the carrier gas at the same point is avoided, the gathering or uneven dispersion of the carrier gas in the flow channel is avoided, the path length of the carrier gas mixing is increased, the carrier gas has more opportunities to mix and disperse, the powder particles are more uniformly distributed in the compressed gas, which helps to prevent local concentration difference and ensures more uniform mixing and distribution of the powder before entering the plasma jet.

[0073] Further, the axial projection of the upper-stage powder inlet hole 102 except the fourth powder inlet hole 401 is located on the symmetry axis formed by the lower-stage powder inlet hole 102, so that when the carrier gas enters the first powder distribution groove 203 through the first powder inlet hole 102, it is uniformly divided into two streams, which can enter the mixing part 3 at the same speed and direction through the two second powder inlet holes 202, and the carrier gas continues to be uniformly divided into four streams after entering the second powder distribution groove 303 through the two second powder inlet holes 202, which can enter the converging part 4 after passing through the four third powder inlet holes 302 at the same speed and direction. Therefore, the uniform distribution of the powder before entering the jet is further ensured, and the quality and performance of the coating are improved.

[0074] Further, the number of the fourth powder inlet holes 401 on the converging part 4 is much larger than the number of the third powder inlet holes 302, and the plurality of fourth powder inlet holes 401 makes the carrier gas more uniformly distributed on the cross section of the jet, and avoids the blockage and accumulation of the powder in the powder feeding device. It is worth mentioning that if the powder feeding rate of part of the powder inlet holes decreases, other powder inlet holes can still work and the spraying process will not be interrupted.

[0075] It should be explained that the number of the fourth powder inlet holes 401 is determined according to the size of the converging part 4 and the shape and size of itself, and the embodiment of the present application does not limit this.

[0076] As a preferred mode of the present embodiment, the fourth-stage powder feeding hole 401 in the mixing component 3 can be inwardly or outwardly inclined at an angle of 0-30° with the horizontal end face. Inward inclination is advantageous for increasing powder residence time and feeding depth, while outward inclination is advantageous for reducing plasma jet disturbance. The specific angle is determined according to the powder feeding carrier gas flow and the plasma working gas flow.

[0077] To further improve the uniformity of the carrier gas distribution, a third-stage distribution assembly is provided between the third-stage powder feeding hole and the fourth-stage powder feeding hole, and is located on the bottom surface of the mixing component 3. The third-stage distribution assembly includes four guide flow channels 304, each of which is connected to a corresponding third-stage powder feeding hole 302. Each guide flow channel 304 starts from the third-stage powder feeding hole 302, extends along the clockwise or counterclockwise direction to the adjacent third-stage powder feeding hole 302, and stops at the midpoint of the line connecting the two powder feeding holes. The mixing flow channel 305 is a circular hole slot formed on the mixing component 3, coaxial with the entire component, and tangent to the outside of the four guide flow channels 304, with the same depth as the guide flow channels 304. The mixing component 3 is internally provided with a recess 306 for placing the converging component 4, with the same diameter as the outer diameter of the converging component 4 and coaxial with the entire component. The upper middle part of the converging component 4 is located in the recess 306, and the lower middle part is embedded at the edge of the mixing flow channel 305. The height of the converging component 4 is the same as the total depth of the recess 306 of the mixing component 3 and the mixing flow channel 305, and when matched with them, the bottom surface of the converging component 4 is flush with the bottom surface of the mixing flow channel 305.

[0078] In some embodiments, the height of the fourth-stage powder feeding hole 401 is lower than the depth of the mixing flow channel 305 of the mixing component 3, which can ensure that the carrier gas in the mixing flow channel 305 can enter the fourth-stage powder feeding hole 401. Further, the fourth-stage powder feeding holes 401 are uniformly spaced along the circumferential direction of the converging component 4 and are arranged on the side wall near the bottom surface of the converging component 4, that is, the fourth-stage powder feeding holes 401 are at the same circumferential height as the bottom surface of the mixing flow channel 305. In this way, by the arrangement of the four guide flow channels 304, the carrier gas is spirally guided from the third-stage powder feeding hole 302 to the mixing flow channel 305, further improving the uniformity of the carrier gas distribution.

[0079] Preferably, the guide flow channel 304 in the mixing component 3 does not coincide with the radius of the powder feeder and is at an angle of about 60°-90°, which increases the circumferential velocity and enables the carrier gas to be fully mixed, thereby improving the uniformity of the compressed gas and the powder.

[0080] In another embodiment, in combination with the above embodiments, please refer to Figure 6 and Figure 7 as shown, Figure 6 is the structure assembly drawing of the water-cooled component 5 shown in the present application; Figure 7is the structural assembly drawing of the shell component 6 shown in the present application. The powder feeding device mainly consists of a fixed component 1, a distribution component 2, a mixing component 3, a confluence component 4, a water cooling component 5 and a shell component 6. The water cooling component 5 is located directly below the mixing component 3, and the entire device is installed in the order from top to bottom. The water cooling component 5 is provided with an annular column, and a plurality of second threaded fixing holes 502 are arranged on the annular column. The plurality of second threaded fixing holes 502 are concentric and equally angularly distributed. The plurality of second threaded fixing holes 502 are bolted to the shell component 6. The number of second threaded fixing holes 502 is at least 3, and preferably 6.

[0081] The shell component 6 can form a water cooling chamber 9 with the water cooling component 5. The shell component 6 is provided with a water inlet and a water outlet 603 which are in communication with the water cooling chamber 9. The water outlet 603 and the water inlet pass through the center of the circle, and both are threaded openings. The two openings can be connected to the water pipe through threaded quick insertion, forming a cooling water passage. The stepped surface of the shell component 6 is provided with a third threaded fixing hole 602, which can be matched with the water cooling component 5 through a bolt. The number and position of the third threaded fixing hole 602 are the same as those of the second threaded fixing hole 502 on the water cooling component 5.

[0082] Preferably, a guide baffle 604 is arranged inside the third threaded fixing hole 602, which provides the initial velocity of the flow direction jet for the carrier gas flowing out of the powder feeding device, so that it can still flow to the jet after flowing out to ensure the utilization rate of the powder. More preferably, the guide baffle 604 forms an angle of 15°-70°, preferably 60°, with the plane of the shell component 6.

[0083] As a specific explanation of the present application, in addition to the confluence component 4, the fixed component 1, the distribution component 2, the mixing component 3, the water cooling component 5 and the shell component 6 are respectively provided with a plurality of positioning holes, and the positioning holes on the corresponding components are located outside the powder inlet hole. The fixed component 1 is provided with a plurality of first positioning holes 101, the distribution component 2 is provided with a plurality of second positioning holes 201, the mixing component 3 is provided with a plurality of third positioning holes 301, the water cooling component 5 is provided with a plurality of fourth positioning holes 501, and the shell component 6 is provided with a plurality of fifth positioning holes 601. The plurality of positioning holes are uniformly arranged around the circumference of the corresponding component. The positions of the first positioning holes 101, the second positioning holes 201, the third positioning holes 301, the fourth positioning holes 501 and the fifth positioning holes 601 are opposite, and the number, shape and size are the same. The above components are connected together in axial overlap by bolts successively passing through the first positioning holes 101, the second positioning holes 201, the third positioning holes 301, the fourth positioning holes 501 and the fifth positioning holes 601.

[0084] In some embodiments, the number of positioning holes should be more than 3, and preferably 6.

[0085] In yet some embodiments, the device further comprises a sealing part, the sealing part comprising a plurality of sealing grooves and a plurality of sealing rings, each of the sealing rings being embedded into each of the sealing grooves; wherein at least a first portion of the sealing grooves are respectively arranged at positions adjacent to two components close to the shunt passage; at least a second portion of the sealing grooves are arranged at positions close to the water-cooling chamber; and the sum of the first portion and the second portion is not greater than the total number of the sealing grooves.

[0086] In the present embodiment, the plurality of sealing grooves are specifically arranged as follows:

[0087] The inner side of the primary distribution groove 203 is provided with a first sealing groove 204, and the outer side of the primary distribution groove 203 and the inner side of the secondary positioning hole 201 are provided with a second sealing groove 205, both of which are coaxial with the entire device, and the first sealing groove 204 and the second sealing groove 205 are provided with sealing rings to prevent large-scale gas leakage.

[0088] The inner side of the tertiary positioning hole 301 of the mixing component 3 is provided with a third sealing groove 307 and a fourth sealing groove 308, both of which are coaxial with the entire device, the third sealing groove 307 is located at the inner side of the secondary distribution groove 303, and the fourth sealing groove 308 is located between the secondary distribution groove 303 and the tertiary positioning hole 301. A fifth sealing groove 309 is arranged between the guide flow channel 304 and the tertiary positioning hole 301 to prevent gas leakage.

[0089] The upper surface of the confluence component 4 is provided with a sixth sealing groove 402. The inner side of the fourth positioning hole 501 and the outer side of the third threaded fixing hole 602 are respectively provided with a seventh sealing groove 503 and an eighth sealing groove 504 for sealing the water-cooling chamber 9. The eighth sealing groove 504 is arranged on the planar side of the water-cooling component 5 and has a radius slightly smaller than that of the confluence component 4, and is mainly used for gas leakage at the mixed flow channel 305 of the confluence component 4.

[0090] Performance test:

[0091] The power of the laminar flow plasma system is set to 19.8 kW, the powder feeding device provided by the present application is numerically simulated, and the related performance is tested.

[0092] The temperature field distribution of the mixed laminar flow plasma jet and the carrier gas output by the powder feeding device provided by the present embodiment is tested, as shown in Figure 8 The temperature distribution statistical diagram of the outlet of the plasma torch under different carrier gas flow rates is shown. When the flow rate of the carrier gas is 2L·min -1 to 10L·min -1 It can be seen that under the condition of reducing the flow rate of the carrier gas and using the powder feeding device, the plasma jet is 4L·min-1 At the flow rate of 4L·min Figure 9 -1 The temperature distribution of the plasma jet outlet and the end turbulent intensity distribution cloud diagram when the carrier gas flow is 4L·min -1 The temperature distribution of the plasma jet outlet and the end turbulent intensity distribution cloud diagram when the carrier gas flow is 4L·min

[0093] The morphology of the laminar flow plasma jet before and after powder feeding and the spraying process schematic diagram are shown in the figure. Figure 10 The morphology of the laminar flow plasma jet before and after powder feeding and the spraying process schematic diagram are shown in the figure. Figure 11 The structure morphology micrograph of the coating formed by the laminar flow plasma spraying is shown in the figure.

[0094] The present application also provides a laminar flow plasma spraying system configured with the disturbance-free laminar flow plasma spraying powder feeding device.

[0095] The specific implementation mode of the system in the embodiment of the present application has been described in detail on the powder feeding device side, and therefore will not be repeated here.

[0096] It should be noted that each embodiment in the present specification adopts a progressive description mode, and each embodiment focuses on the different places from other embodiments, and the same and similar parts between each embodiment can be referred to each other.

[0097] It should be further noted that in this paper, the terms "upper", "lower", "left", "right", "inner", "outer" and the like indicate the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. In addition, relationship terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between the entities or operations, and cannot be understood as indicating or implying relative importance. Moreover, the term "comprising" or any other variant thereof is intended to cover non-exclusive inclusion, so that the process, method, article or terminal device including a series of elements includes not only those elements, but also other elements not explicitly listed or inherent to such process, method, article or terminal device.

[0098] The above describes in detail the powder feeding device and system for the disturbance-free laminar flow plasma spraying provided by the present application. The principles and implementation manners of the present application are described by using specific examples. The above description of the examples is only used to help understand the present application, and the content of the description should not be understood as limiting the present application. Meanwhile, according to the present application, the specific implementation manners and application ranges can be changed in different forms by those skilled in the art, and it is not necessary or possible to enumerate all the implementation manners, and the obvious changes or variations derived therefrom are still within the protection scope of the present application.

Claims

1. A disturbance-free laminar flow plasma spray powder delivery device characterized by, The device is applied to a laminar flow plasma spraying system, a center of the device is formed with a jet flow area for allowing a laminar flow plasma jet to pass through, and the device comprises: The fixed component, the distribution component, and the mixing component are arranged in axial overlap, and the confluence component is arranged in radial overlap with the mixing component and communicates with the jet flow area; wherein, A plurality of powder inlet holes are respectively formed through the fixed component, the distribution component, the mixing component, and the confluence component, and all the powder inlet holes communicate through a shunt channel configured to change a flow path of the carrier gas; wherein, The carrier gas flowing from the powder inlet holes on the corresponding components flows through the shunt channel, radially flows into the jet flow area after speed reduction by shunting of the shunt channel, and prevents the carrier gas from disturbing the laminar flow plasma jet in the jet flow area.

2. A disturbance-free laminar flow plasma spray powder delivery device according to claim 1, wherein, The shunt channel comprises: A first distribution groove is arranged on the distribution component and respectively communicates with a first powder inlet hole on the fixed component and a second powder inlet hole of the first distribution groove; A second distribution groove is arranged on the mixing component and respectively communicates with the second powder inlet hole and a third powder inlet hole of the second distribution groove; A third distribution assembly is arranged on a side of the mixing component opposite to the second distribution groove and respectively communicates with the third powder inlet hole and a fourth powder inlet hole on the mixing component; The carrier gas input from the first powder inlet hole into the first distribution groove is reduced in speed by first shunting, flows into the second distribution groove through the second powder inlet hole and is reduced in speed by second shunting, flows into the third distribution assembly through the third powder inlet hole and is reduced in speed by third shunting, and flows into the jet flow area through the fourth powder inlet hole.

3. A disturbance-free laminar flow plasma spray powder delivery device according to claim 2, wherein, The third distribution assembly comprises a plurality of guide flow channels and a mixing flow channel, each guide flow channel respectively communicates with each third powder inlet hole and the mixing flow channel; wherein, At least part of the confluence component in the axial direction is arranged in the mixing flow channel, and the fourth powder inlet hole is located in the mixing flow channel.

4. A disturbance-free laminar flow plasma spray powder delivery device according to claim 3, wherein, Each guide flow channel extends from the corresponding third powder inlet hole to the midpoint of the line connecting two powder inlet holes in the direction of the adjacent third powder inlet hole in clockwise or counterclockwise.

5. A disturbance-free laminar flow plasma spray powder delivery device according to claim 4, wherein, The extension endpoint of each guide flow channel is tangent to the edge of the mixing flow channel.

6. A disturbance-free laminar flow plasma spray powder delivery device according to claim 2, wherein, The number of the first powder inlet hole, the second powder inlet hole, the third powder inlet hole, and the fourth powder inlet hole gradually increases; and The positions of the adjacent powder inlet holes are staggered, and the axial projection of the upper powder inlet hole is located on the symmetry axis formed by the lower powder inlet hole; The fourth powder inlet hole is configured to be oriented at an angle.

7. A disturbance-free laminar flow plasma spray powder delivery device according to claim 1, wherein, The device further comprises a water cooling component and a shell component, the water cooling component is connected with the mixing component and the shell component in the axial direction; wherein, The water cooling component and the shell component enclose a water cooling chamber for containing a cooling medium.

8. A disturbance-free laminar flow plasma spray powder delivery device according to claim 7, wherein, A guide baffle is arranged on the shell component and extends downwardly in the direction close to the jet flow area.

9. A disturbance-free laminar flow plasma spray powder delivery device according to claim 7, wherein, The device further comprises a sealing part, which comprises a plurality of sealing grooves and a plurality of sealing rings, each of which is embedded in each of the sealing grooves; At least a first part of the sealing grooves are respectively arranged at positions close to the shunt passage between two adjacent components; At least a second part of the sealing grooves are arranged at positions close to the water-cooled chamber; The sum of the first part and the second part is not greater than the total number of the sealing grooves.

10. A laminar flow plasma spraying system characterized by, The disturbance-free laminar flow plasma spraying powder feeding device as claimed in any one of claims 1-9 is configured.

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