A multi-chamber high-power high-efficiency supersonic flame thermal spraying gun and a thermal spraying device thereof

Abstract

This invention discloses a multi-combustion-chamber, high-power, high-efficiency supersonic flame thermal spraying gun and its thermal spraying device. The spray gun includes a gun housing, within which is a core unit comprising a Laval nozzle, several independent combustion chambers, and a gun barrel. A water-cooling jacket is installed outside the gun housing. The expansion section of the Laval nozzle is securely connected to the gun barrel. Independent combustion chambers are evenly installed circumferentially in the middle section of the Laval nozzle. High-pressure air and spray powder enter the Laval nozzle cavity from the tail end of the Laval nozzle. The independent combustion chambers are used to inject an oil-air mixture into the Laval nozzle cavity and ignite it. Multiple double-layer water-cooling channels are formed between the water-cooling jacket, the gun housing, and the core unit. This invention solves the problems of incomplete combustion, uneven temperature distribution, and excessively high gun body temperature and pressure caused by simply increasing the size of the spray gun in traditional solutions to improve thermal spraying efficiency. It has the advantages of large flame size, high power, high powder deposition efficiency, and high water-cooling efficiency.

Description

Technical Field

[0001] This invention relates to the field of surface engineering and remanufacturing coatings, and more particularly to a multi-combustion chamber, high-power, high-efficiency supersonic flame thermal spray gun and its thermal spraying device. Background Technology

[0002] Supersonic flame thermal spraying technology is widely used in surface treatment due to its extremely high flame velocity, relatively low temperature, wide applicability to various spraying materials, high coating adhesion strength, and high coating density. However, it is less efficient and time-consuming when spraying very large parts. This is because the flame size of mainstream advanced supersonic flame thermal spraying guns is relatively small, generally less than 20 mm in diameter. The ultra-high flame velocity requires very high temperature and pressure in the gun's combustion system. Therefore, forcibly increasing the supersonic flame size places extremely high demands on the supply of fuel and oxygen, as well as the combustion process, and significantly increases the burden on the gun's cooling system. Simply increasing the size of the gun body will result in incomplete combustion in the combustion chamber, uneven temperature distribution, heavy load on the water cooling system, high gun body temperature, and uneven powder heating, among other problems. Achieving the process requirements of supersonic flame thermal spraying presents significant technical challenges and safety hazards. If multiple supersonic flame spray guns are used simultaneously for spraying, the flames from the multiple guns will interfere with each other and cause mutual contamination, thus affecting the coating performance. Summary of the Invention

[0003] This invention aims to overcome the bottlenecks of existing technologies and solve the problem of insufficient efficiency when supersonic thermal spraying of ultra-large parts. It provides a supersonic flame thermal spraying gun, apparatus, and coating preparation process with multiple combustion chambers, large flame size, high power, high powder deposition efficiency, and high water cooling efficiency.

[0004] The technical solution adopted by this invention to solve the problem is:

[0005] A multi-combustion chamber, high-power, high-efficiency supersonic flame thermal spray gun includes a gun housing. Inside the gun housing is a core unit comprising a Laval nozzle, several independent combustion chambers, and a gun barrel. A water-cooling jacket is installed outside the gun housing. The diameter of the expansion section of the Laval nozzle matches the diameter of the gun barrel, and the two are tightly connected. Several through holes are evenly distributed around the middle section of the Laval nozzle, and an independent combustion chamber is installed at each through hole. High-pressure air and spray powder enter the Laval nozzle cavity from the tail end of the Laval nozzle. The independent combustion chamber is used to inject an oil-air mixture into the Laval nozzle cavity and ignite it. Multiple double-layer water-cooling channels are formed between the water-cooling jacket, the gun housing, and the core unit.

[0006] The described gun barrel has a larger diameter than traditional thermal spray gun barrels, matching the diameter of the expansion section of the multi-functional Laval nozzle. Its bottom fits tightly with the Laval nozzle orifice, secured by fastening screws and sealed with a high-temperature resistant sealing ring. The barrel diameter ranges from 19mm to 33mm, with larger diameters requiring longer barrels, ideally between 170mm and 450mm. This design increases the flame velocity and allows the powder sufficient time to heat, achieving optimal melting.

[0007] The gun housing consists of a barrel shell, a body shell, and a rear cover. The barrel shell and body shell are connected by a threaded seal, and the contact joint is sealed with a rubber sealing ring to prevent cooling water leakage. The barrel shell opening and the barrel opening are equipped with stabilizing support rings to improve the stability and coaxiality of the barrel, prevent barrel deformation, and extend barrel life. These rings are also sealed with high-temperature resistant sealing rings.

[0008] The water-cooling jacket is connected to the gun body shell by threads and sealed by a sealing ring to ensure smooth water return and sealing.

[0009] The gun body shell is a hollow, irregularly shaped structure that ensures the main frame of the spray gun is threadedly connected to the gun barrel shell and water cooling jacket, sealed with a sealing ring, and has a threaded opening for a water inlet at the rear of the gun body shell.

[0010] The multi-functional Laval nozzle has multiple axially symmetrical through holes evenly distributed on its outer periphery, which can be tightly sealed and connected to multiple independent combustion chambers to form a connected space. Furthermore, the side of the multi-functional Laval nozzle has many small protrusions evenly distributed. The surface of the protrusions fits with the inner wall of the nozzle body, providing a certain degree of support. Grooves exist between the small protrusions, allowing cooling water to flow smoothly. The small protrusions also increase the cooling area of ​​the multi-functional Laval nozzle and the independent combustion chambers, greatly improving cooling efficiency. Furthermore, the inner wall of the tail of the multi-functional Laval nozzle has a ring of limiting protrusions that contact the high-temperature resistant ceramic plate, limiting the position and movement of the high-temperature resistant ceramic plate.

[0011] The multiple independent combustion chambers are sealed to the side through-hole of the multi-functional Laval nozzle on one side and sealed to the oil-gas coaxial injector on the other side. The number of independent combustion chambers is preferably controlled between 3 and 9. Their main function is to distribute the energy required by the spray gun during operation through the multi-point combustion of a large amount of fuel, so as to achieve higher thermal efficiency.

[0012] The high-temperature resistant porous ceramic sheet has two types of through holes. One type of through hole allows the powder feeding needle to pass through. There are multiple through holes, which are axially symmetrically and evenly distributed on the ceramic sheet. The other type of through hole allows high-pressure air to pass through. There are more through holes, which are denser and smaller, and are axially symmetrically and evenly distributed on the ceramic sheet.

[0013] Furthermore, the multiple powder feeding needles and the through holes in the powder feeding needles make the powder feeding more efficient and uniform under the condition of a large powder feeding volume, thereby making the powder heat up more evenly.

[0014] Furthermore, the high-pressure air passage serves two purposes: first, to accelerate the powder, and second, to make the powder more evenly distributed in the flame.

[0015] Furthermore, one side of the ceramic disc contacts a limiting protrusion on the inner wall of the Laval nozzle, and the other side contacts the air separator, and is sealed by the sealing ring of the air separator.

[0016] Furthermore, when the spray gun is working, the high-temperature resistant ceramic plate is heated above the fuel ignition point, providing continuous ignition and greatly improving the combustion state inside the multi-functional Laval nozzle.

[0017] The air separator has many through holes inside, which allows high-pressure air to be evenly transmitted to the multifunctional porous ceramic plate. Both ends of the plate have protrusions. One protrusion is in sealing contact with the ceramic plate, and the other protrusion is in sealing contact with the rear cover of the gun body. It also has multiple threaded holes, which are used to fix the powder feeding needle by engaging with the external thread on the powder feeding needle.

[0018] The powder feeding needles sequentially pass through the powder feeding needle holes of the gun body rear cover, air separator, and high-temperature resistant ceramic plate, and are fastened to fit with the threaded holes in the air separator. Rubber sealing rings can be used to seal the rear cover and air separator sections. The number of powder feeding needles is determined based on the number of independent combustion chambers and the powder feeding rate, generally equal to the number of independent combustion chambers. The diameter of the powder feeding needles is determined by the type and particle size of the sprayed powder, and the position of the powder feeding needles is arranged according to the flame size.

[0019] The gun body rear cover is threadedly connected to the gun body shell and has multiple air inlet holes, water inlet holes, and powder feeding needle holes.

[0020] The described oil-gas mixing atomizer is threadedly connected to the oil-gas coaxial injector and sealed with a sealing ring. The oil-gas mixing atomizer has a sealed hollow structure with a separator with multiple fine holes inside and an oil inlet, an oxygen inlet, and an ignition needle port on the outside. Its main function is to fully and uniformly mix kerosene and oxygen, atomize the mixture through the separator, and then send the oil-oxygen mixture into the oil-gas coaxial injector, from where it is ejected into each independent combustion chamber.

[0021] The oil-gas coaxial injector is in sealed contact with the independent combustion chamber, threadedly connected to the gun body shell, sealed with a sealing ring, and has a coaxial oil-gas outlet and ignition pinhole inside.

[0022] The spray gun can also be equipped with sensing and detection elements such as pressure sensors. In addition, the spray gun can also have supporting equipment including: a central control cabinet, a water chiller with multiple circulating water pumps, a kerosene control box with multiple oil pumps, multiple powder feeders, an air compressor and a refrigerated dryer that can provide clean, dry, high-pressure air, a high-pressure oxygen supply system, and an ignition device, thus forming a complete set of thermal spraying equipment.

[0023] The aforementioned water chiller with multiple circulating water pumps has a water cooling circuit driven by each circulating water pump, which is matched with each inlet and outlet. The performance parameters and quantity of the circulating water pumps and water cooling circuits are based on the heat generated by the entire system, and are required to maintain the temperature of the spray gun within a reasonable range during continuous operation.

[0024] The kerosene control box with multiple oil pumps, each corresponding to an independent combustion chamber, constitutes a spray gun combustion system. The kerosene supply can be connected to an external kerosene pipeline or an external kerosene storage tank.

[0025] The multiple powder feeders have multiple powder feeding tanks and powder feeding pipelines, but the microcomputer control system is integrated into the central control box. The number of powder feeding tanks and powder feeding pipelines is the same as the number of powder feeding needles, which can fully undertake and distribute the task of large powder feeding volume, and the powder feeding state will be more uniform in the multi-functional Laval nozzle.

[0026] The air compressor and refrigerated dryer must provide clean, dry air at pressures and flow rates that meet the compressed air requirements of the spray gun.

[0027] The high-pressure oxygen supply is provided by multiple high-pressure liquid oxygen tanks. After the liquid oxygen is vaporized by the vaporization tower, multiple pipelines connect the oxygen to the oxygen inlet of the oil-gas mixing atomizer on each independent combustion chamber. Each branch pipeline has a pressure reducing valve to regulate the oxygen supply of each branch pipeline.

[0028] The ignition device uses multi-line high-voltage spark plugs to ignite independent combustion chambers. Each line is matched with a spark plug and an independent combustion chamber, forming multiple independent ignition systems.

[0029] The central control cabinet integrates the switching and adjustment of multiple water cooling systems, high-pressure air systems, powder delivery systems, oil supply systems, oxygen supply systems, and ignition systems, and monitors the status of each system. If a problem occurs, it can promptly provide feedback and alarm.

[0030] The specific working process of the device of the present invention is as follows:

[0031] (1) Check whether the power supply system, gas supply system, oil supply system, powder delivery system and ignition system are in normal condition and whether there are any problems;

[0032] (2) Turn on the water chiller to put the spray gun in a water-cooled state. Multiple cooling water enters from the water inlet at the tail end of the spray gun, first flows through the independent combustion chamber, then flows through the converging section, throat and expansion section of the multi-functional Laval nozzle, then flows through the barrel, flows out from the opening at the front of the barrel shell, enters the space between the water cooling jacket and the barrel shell, then enters the space between the water cooling jacket and the gun body shell, and finally exits from the water cooling jacket outlet and returns to the water chiller. The multi-channel double-layer water-cooled spray gun structure greatly increases the water cooling area and significantly improves the water cooling efficiency.

[0033] (3) Open the high-pressure air and powder carrier gas. The powder carrier gas can be argon, nitrogen or other inert gas, so that the independent combustion chamber, multi-functional Laval nozzle and gun barrel inside the spray gun are under a certain pressure and flow rate.

[0034] (4) Simultaneously turn on the kerosene pump and oxygen supply switch, and adjust them to the appropriate flow range required for ignition. The kerosene and oxygen are fully mixed through the oil-gas atomizer to form an oil-gas mist that is discharged from the outlet to each independent combustion chamber, converges into the multi-functional Laval nozzle, and is discharged from the gun barrel.

[0035] (5) Simultaneously turn on the ignition system switch to ignite multiple independent combustion chambers at the same time. At this time, the internal space of the spray gun is rapidly pressurized. The flame passes through the Laval nozzle converging section and its speed increases. The flame passes through the throat of the multi-functional Laval nozzle and then through the expansion section to form a supersonic flame. It then passes through the barrel section for further acceleration.

[0036] (6) After the ignition process is completed, the air, kerosene and oxygen flow rates are automatically adjusted to the set parameters required for spraying the spray gun, the flame speed is further increased, and the temperature of the high-temperature resistant ceramic sheet rises above the melting point of the fuel, which has the function of continuous ignition and heating, further enhancing the combustion state inside the multi-functional Laval nozzle, and finally forming a supersonic flame of Mach 5-9.

[0037] (7) Simultaneously turn on the powder feeder switch to feed powder from multiple powder feeders at the same time. The powder is fully heated and accelerated at the center of the flame, and the state becomes a uniform and stable flame in a supersonic melting state, which is then ejected through the gun barrel.

[0038] (8) The powder is sprayed onto the workpiece surface at the center of the flame, which greatly reduces the powder escape and greatly improves the deposition rate. At the same time, the mixing of multiple centrally symmetrically distributed powder streams solves the problems of uneven distribution of spot powder and excessive accumulation of powder in single-axis powder feeding.

[0039] When preparing a coating using the apparatus of the present invention, the preferred process parameters are as follows:

[0040] The kerosene flow rate in a single independent combustion chamber is 10–30 L / h, and the kerosene pressure is 1.5–1.8 MPa; the oxygen flow rate is 700–1000 L / min, and the pressure is 1.8–3 MPa; the high-pressure air flow rate is 10–90 m³ / min. 3 The pressure is 0.8-1 MPa; a cooling water flow rate of 3000-5000 L / h is required; the nitrogen flow rate corresponding to a single powder feeding needle is 5-15 L / min, and the nitrogen pressure is 0.8-1.2 MPa. If the number of independent combustion chambers is n (recommended value is 3-9), then the total kerosene flow rate is n (10-30 L / h), the oxygen flow rate is n (700-1000 L / min), and the cooling water flow rate is n (3000-5000 L / h). If the number of powder feeding needles is m (recommended value is 3-9), then the total nitrogen flow rate is m (5-30 L / min). Additionally, the recommended flame diameter range is 34.5 mm-60 mm, ensuring coating performance no less than current mainstream levels and significantly improving production efficiency.

[0041] This invention integrates multiple independent combustion chambers with a multi-functional Laval nozzle and an ultra-large diameter barrel (19-33mm) to form a supersonic flame spray gun structure. It solves the problems of incomplete combustion, uneven temperature distribution, and significant safety hazards caused by excessively high gun temperature and pressure, which arise from simply increasing the size of the spray gun in traditional solutions to improve thermal spraying efficiency. This invention employs an innovative multi-path symmetrical uniform distribution powder flow to synthesize a large-diameter, high-volume, and uniformly distributed powder stream. Multiple independent combustion chambers disperse and fully combust at multiple points, achieving higher thermal efficiency. This places the large-diameter powder stream at the center of the flame, greatly improving the powder deposition rate and uniformity on the part surface, and significantly reducing spraying time. Furthermore, the innovative multi-path double-layer water-cooling system greatly improves the water-cooling efficiency of the spray gun. This is a novel supersonic flame thermal spray gun with a large flame size, high power, high powder deposition efficiency, and high water-cooling efficiency, effectively applicable to coating ultra-large parts. Attached Figure Description

[0042] Figure 1 A schematic diagram of a multi-combustion chamber, high-power, high-efficiency supersonic flame thermal spray gun.

[0043] Figure 2 A schematic diagram of a multi-combustion chamber, high-power, high-efficiency supersonic flame thermal spraying device;

[0044] Figure 3 A schematic diagram of a multifunctional Laval nozzle structure;

[0045] Figure 4 A schematic diagram of a high-temperature resistant ceramic sheet structure.

[0046] In the diagram: 1-Water cooling jacket, 2-First cooling water channel, 3-Barrel housing, 4-Second cooling water channel, 5-Barrel, 6-Stabilizing support ring, 7-Bug housing, 8-Multi-functional Laval nozzle, 9-Water outlet, 10-Independent combustion chamber, 11-Oil-gas coaxial injector, 12-Oil-gas mixing atomizer, 13-Oxygen inlet, 14-Kerosene inlet, 15-Separator, 16-Water inlet, 17-High-pressure air inlet, 18-Powder delivery needle, 19-Air distributor, 20-High-temperature resistant ceramic plate, 21-Bug rear cover, 22-Ignition needle port. Detailed Implementation

[0047] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings.

[0048] Reference Figure 1 This diagram illustrates the structure of a four-combustion-chamber, high-power, high-efficiency supersonic flame thermal spray gun. The gun barrel 5 has a larger diameter than traditional thermal spray gun barrels, and its bottom fits tightly with the Laval nozzle orifice, secured by fastening screws and sealed with a high-temperature resistant sealing ring. The barrel 5 serves two purposes: increasing the flame velocity and allowing the powder sufficient time to heat and reach its optimal melting state. The barrel shell 3 and the gun body shell 7 are connected by a threaded seal, and the contact joint is sealed with a rubber sealing ring to prevent cooling water leakage. A stabilizing support ring 6 is incorporated at both the barrel shell orifice and the barrel inlet to improve barrel stability and coaxiality, prevent barrel deformation, and extend barrel life; it is also sealed with a high-temperature resistant sealing ring. The water-cooling jacket 1 is threaded onto the gun body shell 3 and sealed with a sealing ring to ensure smooth return of cooling water in the first cooling water channel 2. The gun body shell 3 is a hollow, irregularly shaped structure that ensures the main frame of the spray gun. It is threadedly connected to the barrel shell 3 and the water cooling jacket 1, and sealed with a sealing ring. A threaded opening for the water inlet is provided at the rear of the gun body shell 3. The multi-functional Laval nozzle 8 has four axisymmetric through holes on its side, evenly distributed, which can be tightly sealed to multiple independent combustion chambers 10 to form a connected space. In order to ensure smooth flame flow, the angle between the axis of the independent combustion chamber and the axis of the Laval nozzle should not be too large or too small; an angle of 30° to 45° is optimal.

[0049] refer to Figure 2 A detailed schematic diagram of a multi-functional Laval nozzle structure is shown. The multi-functional Laval nozzle 8 features numerous small protrusions evenly distributed on its side. These protrusions fit snugly against the inner wall of the gun body shell 3, providing some support. Simultaneously, a certain distance exists between the small protrusions, allowing cooling water to flow smoothly through the second cooling water channel 4. The small protrusions also increase the contact area between the multi-functional Laval nozzle 8 and the cooling water, significantly improving cooling efficiency. Furthermore, a ring of protrusions on the inner wall of the tail of the multi-functional Laval nozzle 8 contacts the high-temperature resistant ceramic plate 20, serving to limit the position and movement of the high-temperature resistant ceramic plate 20.

[0050] refer to Figure 3 A schematic diagram of a high-temperature resistant ceramic sheet structure suitable for four powder feeding needles is shown. The high-temperature resistant ceramic sheet 20 has two types of through holes. One type of through hole allows the powder feeding needles to pass through; there are four through holes, symmetrically and evenly distributed on the ceramic sheet. The reasonable distance between the through holes ensures that the powder flow cross-section has an equal amount of powder. The other type of through hole is for high-pressure air; these through holes are more numerous, denser, and smaller, and are also symmetrically and evenly distributed on the high-temperature resistant ceramic sheet 20. Their functions are twofold: to accelerate the powder and to make the powder distribution in the flame more uniform. The four powder feeding needles ensure the large powder delivery required for spraying, making powder delivery more efficient and uniform, thereby resulting in more even heating of the powder.

[0051] One side of the high-temperature resistant ceramic disc 20 contacts a limiting protrusion on the inner wall of the multi-functional Laval nozzle 8, and the other side contacts the air separator 19, and is sealed by the sealing ring of the air separator 19. When the spray gun is working, the high-temperature resistant ceramic disc 20 is heated above the fuel melting point, and has a continuous ignition function, which can greatly improve the combustion state inside the multi-functional Laval nozzle 8. The air separator 19 has many through holes inside, so that high-pressure air is evenly transmitted to the multi-functional porous ceramic disc 20. Both ends of the air separator 19 have a ring of protrusions. One end of the protrusion is in sealing contact with the ceramic disc 20, and the other end of the protrusion is in sealing contact with the gun body rear cover 21. It also has four threaded holes, which are used to fix the powder feeding needle 18 by engaging with the external thread on the powder feeding needle. The gun body rear cover 21 is threaded to the gun body shell 3 and has four air inlet holes, water inlet holes, and powder feeding needle holes. The oil-gas mixing atomizer 12 has a hollow structure with a multi-pore separator 15 inside and an oil inlet 14, an oxygen inlet 13, and an ignition needle port 22 on the outside. Its main function is to fully and uniformly mix and atomize the kerosene and oxygen, and then send the oil-oxygen mixture into the oil-gas coaxial injector 11, which sprays it into each independent combustion chamber 10. It is threadedly connected to the oil-gas coaxial injector 11 and sealed with a sealing ring. The oil-gas coaxial injector 11 is in sealed contact with the high-temperature sealing ring of the independent combustion chamber 8 and is threadedly connected to the gun body shell 7, also sealed with a sealing ring. It has a coaxial oil-gas outlet and an ignition needle port inside.

[0052] refer to Figure 4This document presents a schematic diagram of a high-power, high-efficiency supersonic flame thermal spraying device with four combustion chambers. It includes a water-cooled system with four circulating water pumps, each pump driving a water-cooling circuit with its own inlet and outlet, designed to maintain the spray gun's temperature within a reasonable range during continuous operation. A kerosene control box with four oil pumps, each corresponding to an independent combustion chamber, forms a spray gun combustion system. Kerosene supply can be provided via external kerosene pipelines or a kerosene storage tank. The powder feeder has four powder tanks and pipelines, effectively handling large powder delivery volumes, and ensuring more uniform powder distribution within the multi-functional Laval nozzle. The air compressor and refrigerated dryer provide clean, dry air with pressure and flow rate sufficient to meet the spray gun's compressed air requirements: pressure 0.8-1 MPa, flow rate 10-90 m³ / h. 3 / min. High-pressure oxygen supply can be achieved using eight high-pressure liquid oxygen tanks. After vaporization in a vaporization tower, the liquid oxygen is connected to the oxygen inlet of the oil-air mixing atomizer on each independent combustion chamber 10 via four pipelines. Each branch pipeline uses an oxygen pressure reducing valve to regulate its oxygen supply. The ignition device uses four-wire high-pressure spark plugs to ignite the independent combustion chambers 10, forming four independent ignition systems. The central control cabinet integrates the switching and adjustment of the water cooling system, high-pressure air system, powder delivery system, oil supply system, oxygen supply system, and ignition system, and monitors the status of each system. In case of problems, it can promptly provide alarm feedback.

[0053] The specific working process of the device and method of the present invention is as follows:

[0054] (1) Check whether the power supply system, gas supply system, oil supply system, powder delivery system and ignition system are in normal condition and whether there are any problems;

[0055] (2) Turn on the water chiller to put the spray gun in a water-cooled state. The four cooling water channels enter from the water inlet 16 at the tail end of the spray gun, flow through the second cooling water channel 4 and the first cooling water channel 2, and then flow back to the water chiller. The multi-channel double-layer water-cooled spray gun structure greatly increases the water-cooled area and significantly improves the water-cooling efficiency.

[0056] (3) Open the high-pressure air and the powder carrier gas. The powder carrier gas can be argon, nitrogen or other inert gas, so that the space of the independent combustion chamber 10 of the spray gun, the multi-functional Laval nozzle 8 and the gun barrel 5 is under a certain pressure and flow rate.

[0057] (4) Simultaneously turn on the four kerosene pumps and oxygen supply switches, and adjust them to the appropriate flow range required for ignition. Kerosene and oxygen are fully mixed through the oil-gas atomizer 12 to form an oil-gas mist that is sprayed from the coaxial outlet into each independent combustion chamber 10, and then converges into the multi-functional Laval nozzle 8 and is sprayed from the gun barrel 5 outlet.

[0058] (5) Simultaneously turn on the ignition system switch to ignite the four independent combustion chambers at the same time. At this time, the internal space of the spray gun is rapidly pressurized. The flame passes through the converging section of the Laval nozzle 8 and the speed is increased. The flame passes through the throat of the multi-functional Laval nozzle 8 and then through the expansion section to form a supersonic flame. It is further accelerated by the barrel section 5.

[0059] (6) After the ignition process is completed, the air, kerosene and oxygen flow rates are automatically adjusted to the set parameters required for spraying the spray gun, the flame speed is further increased, and the temperature of the high-temperature resistant ceramic sheet 20 rises above the fuel melting point, which has the function of continuous ignition and heating, further enhancing the combustion state inside the multi-functional Laval nozzle 8, and finally forming a supersonic flame of Mach 5-9.

[0060] (7) Simultaneously turn on the four powder feeder switches to feed powder through the four powder feeding needles at the same time. The powder is fully heated and accelerated at the center of the flame, and the state becomes a uniform and stable flame in a supersonic melting state, which is then ejected through the gun barrel.

[0061] (8) The powder is sprayed onto the workpiece surface at the center of the flame, which greatly reduces the powder escape and greatly improves the deposition rate. At the same time, the mixing of multiple centrally symmetrically distributed powder streams solves the problems of uneven distribution of spot powder and excessive accumulation of powder in single-axis powder feeding.

[0062] Specific Implementation Case 1 of Coating Process Parameters

[0063] The process parameters for preparing the WC-10Co-4Cr powder coating using a four-combustion-chamber high-power, high-efficiency supersonic flame thermal spray are as follows: kerosene flow rate in a single independent combustion chamber is 24 L / h, kerosene pressure is 1.7 MPa; oxygen flow rate is 850 L / min, pressure is 2.0 MPa; nitrogen flow rate for powder delivery via a single powder delivery needle is 10 L / min, pressure is 1 MPa; high-pressure air flow rate is 20 m³ / min. 3 The pressure is 1.0 MPa; a single water pump needs to provide a cooling water flow rate of 4000 L / h. The total kerosene flow rate is 96 L / h, oxygen flow rate is 3400 L / min, and cooling water flow rate is 16000 L / h. The total nitrogen flow rate for powder delivery is 40 L / min. The distance between the spray gun and the workpiece is 690 mm. The 4-combustion chamber supersonic flame thermal spray gun and the 4-way symmetrical and uniformly distributed powder delivery method greatly increase the effective powder flow area in the flame, increasing the deposition rate to about 67%, which is about 23% higher than the current advanced oxygen-kerosene supersonic flame thermal spray gun with a deposition rate of about 42%. At the same time, the flame diameter is about 40 mm, which reduces the spraying time of the same thickness and area coating by about 84%, significantly improving the coating production efficiency. Moreover, the performance indicators of the prepared coating are: coating-substrate bonding strength ≥82 MPa, coating porosity ≤0.6%, and average microhardness 1270 HV. 0.2Its anti-wear performance is about 11.5 times that of 0Cr13Ni5Mo stainless steel.

[0064] Specific Implementation Case 2 of Coating Process Parameters

[0065] The process parameters for preparing the four-combustion-chamber high-power, high-efficiency supersonic flame thermal spraying Co-Cr-Ni-Al-Y powder coating are as follows: kerosene flow rate in a single independent combustion chamber is 22 L / h, kerosene pressure is 1.7 MPa; oxygen flow rate is 830 L / min, pressure is 1.9 MPa; nitrogen flow rate for powder delivery via a single powder delivery needle is 10 L / min, pressure is 1 MPa; high-pressure air flow rate is 16 m³ / min. 3 The pressure is 1 MPa; a single water pump needs to provide a cooling water flow rate of 4000 L / h. The total kerosene flow rate is 88 L / h, oxygen flow rate is 3320 L / min, and cooling water flow rate is 16000 L / h. The total nitrogen flow rate for powder delivery is 40 L / min. The distance between the spray gun and the workpiece is 600 mm. The deposition rate is increased to approximately 69.5%, which is about 24.5% higher than the current advanced oxy-kerosene supersonic flame thermal spray gun with a deposition rate of approximately 45%. At the same time, the flame diameter is approximately 40 mm, which reduces the spraying time of the same thickness and area coating by approximately 84%, significantly improving the coating production efficiency. The performance parameters of the prepared Co-Cr-Ni-Al-Y alloy coating are: average porosity ≤0.5%, coating bonding strength ≥67 MPa, thermal shock resistance at 700℃ ≥40 cycles, and surface roughness Ra of approximately 6.1 μm, which is beneficial to the bonding between the working layer and the transition layer.

[0066] Specific Implementation Case 3 of Coating Process Parameters

[0067] The process parameters for preparing the WC-12Co powder coating using a four-combustion-chamber high-power, high-efficiency supersonic flame thermal spray are as follows: kerosene flow rate in a single independent combustion chamber is 23 L / h, kerosene pressure is 1.7 MPa; oxygen flow rate is 840 L / min, pressure is 1.9 MPa; nitrogen flow rate for powder delivery via a single powder delivery needle is 10 L / min, pressure is 1 MPa; high-pressure air flow rate is 18 m³ / min. 3The pressure is 1.0 MPa; a single water pump needs to provide 4000 L / h of cooling water. The total kerosene flow rate is 92 L / h, oxygen flow rate is 3360 L / min, and cooling water flow rate is 16000 L / h. The total output powder nitrogen flow rate is 40 L / min. The distance between the spray gun and the workpiece is 650 mm. The 4-combustion chamber supersonic flame thermal spray gun and the 4-way symmetrical and uniformly distributed powder flow greatly increase the effective powder flow area in the flame, increasing the deposition rate to about 66%, which is about 26% higher than the current advanced oxygen-kerosene supersonic flame thermal spray gun with a deposition rate of about 40%. At the same time, the flame diameter is about 40 mm, which reduces the spraying time of the same thickness and area coating by about 85%, significantly improving the coating production efficiency. Moreover, the performance indicators of the prepared coating are: coating-substrate bonding strength ≥76 MPa, coating porosity ≤0.9%, and average microhardness 1150 HV. 0.2 .

[0068] The above description is only a preferred embodiment of the present invention. Any changes made without departing from the technical essence of the present invention should be considered within the protection scope of the present invention.

Claims

1. A multi-combustion chamber, high-power, high-efficiency supersonic flame thermal spray gun, characterized in that, The spray gun includes a spray gun housing, within which is a core unit comprising a Laval nozzle, several independent combustion chambers, and a barrel. A water-cooling jacket surrounds the spray gun housing. The diameter of the expansion section of the Laval nozzle matches the diameter of the barrel, and the two are securely connected. Several through-holes are evenly distributed circumferentially in the middle section of the Laval nozzle, with an independent combustion chamber installed at each through-hole. High-pressure air and spray powder enter the Laval nozzle cavity from the tail end of the nozzle. The independent combustion chambers inject an oil-air mixture into the Laval nozzle cavity and ignite it. Multiple double-layer water-cooling channels are formed between the water-cooling jacket, the spray gun housing, and the core unit. The barrel diameter is 19mm~33mm. Each independent combustion chamber has a cylindrical structure, with one end sealed to the through-hole on the Laval nozzle, and the other end sequentially fitted with an oil-air coaxial injector and an oil-air mixture mist. The atomizer, or fuel-air mixing atomizer, is used to mix fuel and oxygen evenly and atomize them before sending them to the coaxial fuel-air injector, which then injects them into the independent combustion chamber. The fuel-air mixing atomizer and the coaxial fuel-air injector are respectively provided with through-hole ignition needles for inserting ignition needles into the independent combustion chambers. There are 3 to 9 independent combustion chambers evenly distributed around the circumference of the Laval nozzle. The tail of the Laval nozzle is provided with a high-temperature resistant porous ceramic plate and an air separator in sequence. The air separator and the high-temperature resistant ceramic plate are respectively provided with several axisymmetrically evenly distributed powder feeding needles for inserting powder feeding needles into the Laval nozzle cavity. The air separator is evenly distributed with through holes for evenly transmitting high-pressure air to the high-temperature resistant porous ceramic plate. The high-temperature resistant porous ceramic plate is evenly distributed with fine holes for evenly transmitting high-pressure air to the Laval nozzle cavity.

2. The multi-combustion chamber, high-power, high-efficiency supersonic flame thermal spray gun according to claim 1, characterized in that, The inner wall of the Laval nozzle is provided with a ring of limiting protrusions, and both ends of the air separator have a ring of protrusions. One side of the high-temperature resistant porous ceramic sheet is in close contact with the limiting protrusions, and the other side is in sealed contact with one end of the air separator protrusion. The other end of the air separator protrusion is in sealed contact with the spray gun housing. The powder feeding needle hole on the air separator has threads to engage with the powder feeding needle thread.

3. The multi-combustion chamber, high-power, high-efficiency supersonic flame thermal spray gun according to claim 1, characterized in that, The spray gun housing and the core unit form a first sealed space, and the water cooling jacket and the spray gun housing form a second sealed space. Several water inlets are opened at the end of the spray gun housing, and several openings are opened at the front end of the spray gun housing. The openings connect the first sealed space and the second sealed space. The water cooling jacket has an equal number of water outlets at its end to the number of water inlets, thereby forming a multi-channel double-layer water cooling channel.

4. The multi-combustion chamber high-power high-efficiency supersonic flame thermal spray gun according to claim 1, characterized in that, The outer wall of the Laval nozzle is uniformly provided with several independent bosses. The surface of the bosses is fitted with the nozzle housing with a clearance, and cooling water passes between the bosses.

5. The multi-combustion chamber high-power high-efficiency supersonic flame thermal spray gun according to claim 1, characterized in that, The spray gun housing includes a gun body housing located outside the Laval nozzle and independent combustion chamber, a gun barrel housing located outside the gun barrel, and a gun body rear cover located outside the tail of the Laval nozzle. A stabilizing support ring is provided between the head end of the gun barrel housing and the gun barrel and is sealed. The end of the gun barrel housing is sealed to the gun body housing. The gun body rear cover is sealed to both the gun body housing and the end of the Laval nozzle.

6. The multi-combustion chamber, high-power, high-efficiency supersonic flame thermal spray gun according to claim 1, characterized in that, The spray gun should meet the following requirements during spraying: for each independent combustion chamber, the fuel flow rate is 10~30L / h, and the kerosene pressure is 1.5~1.8 MPa; Oxygen flow rate is 700-1000 L / min, pressure is 1.8-3 MPa; a cooling water flow rate of 3000-5000 L / h is required accordingly; high-pressure air flow rate is 10-90 m³ / h. 3 The nitrogen flow rate for a single powder delivery needle is 5–15 L / min, and the nitrogen pressure is 0.8–1.2 MPa.

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