An electric field assisted detonation spray apparatus and method

Abstract

The present application relates to a kind of electric field auxiliary explosion spray equipment and method, including insulator, small explosion chamber and main reaction chamber;Small explosion chamber is connected with main reaction chamber by injection channel, annular chamber and explosion combustion product annular shunt chamber;Small explosion chamber is equipped with combustible gas first air inlet, combustible gas second air inlet and spark plug;The upper portion of main reaction chamber is equipped with combustible gas third channel, combustible gas annular shunt and combustible gas fourth channel;The lower portion of main reaction chamber is equipped with powder feeding channel, gas-powder mixture annular shunt and feeding chamber;Powder feeding pipeline is connected with gas-powder mixture annular shunt, and gas-powder mixture annular shunt is connected with disc-shaped feeding chamber;Rod-shaped metal anode is introduced in the equipment of the present application, and the end of rod-shaped metal anode is melted, gasified by high-energy plasma jet during spraying operation, mixed into explosion product with plasma jet, sprayed to the surface of workpiece, can control coating composition, and play the effect of alloying.

Description

Technical Field

[0001] This invention relates to the field of thermal spraying technology, and in particular to an electric field-assisted explosive spraying device and method. Background Technology

[0002] Existing Patent ①: An explosive spraying method (US Patent No.: 2714563). This method introduces a mixture of oxygen and acetylene, along with powdered material, into a combustion chamber. A spark plug ignites the combustible mixture, causing an explosion. The explosive gas flow heats, accelerates, and bombards the powder onto the workpiece surface, forming a coating. This method controls the temperature and velocity of the combustion products by introducing inert gas and a diluent (e.g., nitrogen) into the combustion chamber. After each spraying cycle, inert gas is first introduced into the combustion chamber, followed by explosive gas, ultimately triggering an explosion for the next spraying cycle, which is repeated continuously. The spraying pulse frequency is 4–8 Hz. The velocity of the explosive shock wave is 1860–3100 m / s, and the combustion product velocity reaches up to 1400 m / s, with temperatures reaching up to 4000 K.

[0003] Existing Patent ②: Method and Apparatus for Preparing Coatings Using Plasma Technology (Russian Patent: 1225273). This method involves introducing an inert gas between the anode and the hot cathode, which ionizes to form a compressed plasma beam. Powder with a particle size of 30–45 μm is then fed into the plasma beam outlet at a feed rate of 8–10 g / min. The inert gas pressure is 5.3–8.0 Pa, and the anode voltage is 300–400 V. The apparatus includes an evaporator, a discharge chamber, a hot cathode, and an anode. An intermediate electrode with a conical cavity is placed coaxially with the discharge chamber. The angle between the centerline of the conical cavity and the axis of symmetry of the discharge chamber is 47°–50°. The evaporator is made of a non-magnetic material and has plasma and vapor channels, as well as a powder feeding channel.

[0004] Existing Patent ③: An explosive spraying device (International Patent No.: WO 98 / 29191) uses propane, butane, propylene, and ethylene as combustible gases. The device includes a combustion chamber, a mixing chamber for mixing the combustible gases, a spark plug, and a powder feeding system. The device operates at a high frequency and can continuously supply combustible gas mixture and powder. The shape of the combustion chamber and the type of gas supply system are not limited.

[0005] Existing Patent ④: A plasma explosion spraying device for metal products (European Patent Application No.: 0531527A1 / International Patent No.: WO 92 / 17619). This device includes a reaction chamber containing electrodes, and the reaction chamber is connected to a detonating device. The reaction chamber contains one or more powder feeding pipes, through which spraying powder is fed into the reaction chamber. The spraying material can be elements from Groups IV, V, and VI of the periodic table. A key feature of this patented device is that the detonator is installed outside the reaction chamber.

[0006] The disadvantages of the existing patent ① are that, due to the use of an electromechanical system for gas and powder supply, the device itself is constrained by inertia and cannot achieve a high frequency; the energy generated by the explosion is affected by factors such as the content and volume of the combustible mixture, the loss due to heating the combustion chamber wall, and the energy transfer loss from gas to powder, which limits the production efficiency and coating quality of the spraying.

[0007] The disadvantages of existing patent ② are: it has certain limitations on the performance of powder materials and coatings; the process requires vacuuming and filling with inert gas, and is finally carried out in an inert atmosphere, which is technically difficult and has a limited range of applications.

[0008] The disadvantages of the existing patent ③ are: insufficient energy of a single pulse, which limits the scope of application; incomplete combustion of the combustible mixture, energy loss on the combustion chamber wall, and energy loss during the process of powder flying from the edge of the nozzle to the sprayed surface.

[0009] The disadvantages of existing patent ④ are: The detonation occurs in an unactivated combustible mixture, limiting the application scope and stability of the technology. When the combustible mixture is not activated, spark plug ignition is unstable, resulting in an unstable combustion process. The combustion process of the combustible mixture in this explosive spraying method and apparatus is carried out under standard atmospheric pressure, thus limiting the energy of the combustion products; when using refractory powder for spraying, the energy of the explosive combustion products is insufficient, making it difficult to obtain a high-quality coating. Furthermore, during the spraying process, the shock wave from the edge of the combustion chamber nozzle reflects off the surface of the part being sprayed and collides with the powder flying towards the part, reducing the powder's velocity and thus lowering the coating quality.

[0010] Therefore, it is necessary to improve upon the above-mentioned issues. Summary of the Invention

[0011] The main objective of this patent is to provide an electric field-assisted explosive spraying device and a method for preparing a coating using the device. The device and method can increase the temperature of the working gas and the spraying speed of the spraying powder to be higher than the speed of the products of simple explosion and combustion, thereby achieving efficient spraying and obtaining a coating with good physical and mechanical properties.

[0012] To achieve the above objectives, the technical solution adopted by this invention is as follows: an electric field-assisted explosive spraying device, comprising an insulator, a small explosion chamber, and a main reaction chamber; the small explosion chamber is connected to the main reaction chamber via a spray channel, an annular chamber, and an annular distributor for explosion and combustion products; the small explosion chamber is provided with a first combustible gas inlet, a second combustible gas inlet, and a spark plug; the upper part of the main reaction chamber is provided with a third combustible gas channel, an annular distributor for combustible gas, and a fourth combustible gas channel; the lower part of the main reaction chamber is provided with a powder feeding channel, an annular distributor for a gas-powder mixture, and a feeding chamber; the powder feeding channel is connected to the annular distributor for the gas-powder mixture, and the annular distributor for the gas-powder mixture is connected to the disc-shaped feeding chamber; the powder feeding channel is connected to the powder feeder; a main reaction chamber wall is formed on the outer side of the main reaction chamber, and the main reaction chamber wall is connected to the negative terminal of the power supply via a cathode conductive block; a cooling gas annular distributor is provided on the upper part of the insulator, and the cooling gas passes through the first cooling gas... The cooling gas enters through a two-channel annular distributor and then enters the insulator for cooling. A conical electrode is arranged along the axis of the main reaction chamber and fixed to the insulator. A movable copper tube is installed along the axis of the conical electrode, with a rod-shaped metal anode fixed inside. The rod-shaped metal anode extends from the end of the copper tube to the tip of the conical electrode. The rod-shaped metal anode is connected to the copper tube via an anode conductive block and to the positive terminal of the power supply. The negative terminal of the power supply is connected to the workpiece. A first cooling gas channel is installed on the wall of the copper tube to deliver the cooling gas into the tube. A nozzle is installed below the main reaction chamber, with an obliquely cut outlet. A compressed air annular distributor is located at the nozzle outlet. The system also includes a gas control system, a power control system, and an ignition device. The power control system controls pulse power supply, the gas control system controls gas and powder supply, and the ignition device controls spark plug ignition.

[0013] As a preferred embodiment of the present invention, the nozzle has a beveled opening at its outlet, the bevel angle of which is 25° to 60°.

[0014] As a preferred embodiment of the present invention, the outer wall of the conical electrode has the same taper and is coaxial with the wall of the main reaction chamber.

[0015] In a preferred embodiment of the present invention, the rod-shaped metal anode is a solid rod.

[0016] In a preferred embodiment of the present invention, the rod-shaped metal anode is a core rod.

[0017] In a preferred embodiment of the present invention, the feeding chamber has a disc-shaped structure, and the feeding chamber surrounds the nozzle to form an annular cavity.

[0018] In a preferred embodiment of the present invention, the feeding chamber, the annular distributor for explosion and combustion products, the annular distributor for compressed air, the annular distributor for gas-powder mixture, the annular distributor for combustible gas, and the annular distributor for cooling gas are made of metallic materials.

[0019] As a preferred embodiment of the present invention, the cross-sectional height of the feeding chamber is 5 to 15 times the average particle size of the sprayed powder.

[0020] In a preferred embodiment of the present invention, the outer diameter of the feeding chamber is 60-80 mm larger than the diameter of the nozzle.

[0021] As a preferred embodiment of the present invention, the annular chamber and the main reaction chamber are equipped with a water cooling system.

[0022] As a preferred embodiment of the present invention, the high-voltage pulse frequency of the ignition device is 2 to 15 Hz.

[0023] In a preferred embodiment of the present invention, the distance from the nozzle outlet to the workpiece is 20 to 200 mm.

[0024] A method for electric field-assisted explosive spraying includes the following steps:

[0025] Step 1: According to the coating design requirements, select the material of the rod-shaped metal anode, insert the rod-shaped metal anode into the copper tube, determine the extension length of the rod-shaped metal anode at the tip of the conical electrode, and fix it coaxially with the copper tube and the conical electrode.

[0026] Step 2: Load an appropriate amount of coating powder into the powder feeder;

[0027] Step 3: Set the flow rate of each powder and gas delivery channel through the gas control system;

[0028] Step 4: Set the high-voltage pulse frequency of the ignition device through the power control system and set the spraying process specifications;

[0029] Step 5: Control the motion trajectory of the workpiece through the motion system;

[0030] Step 6: Open the solenoid valves of the first and second combustible gas inlets to supply gas to the small explosion chamber; simultaneously, combustible gas is introduced into the main reaction chamber through the third combustible gas channel, the combustible gas annular distributor, and the fourth combustible gas channel; a gas-powder mixture is introduced into the main reaction chamber through the powder feeding channel, the gas-powder mixture annular distributor, and the feeding chamber, where the combustible gas and the gas-powder mixture are compressed; connect the power supply to form an electric field between the main reaction chamber wall and the conical electrode; the first cooling gas channel supplies cooling gas, and the second cooling gas channel supplies inert gas;

[0031] Step 7: The ignition device controls the spark plug to ignite according to the set pulse frequency, which produces an explosion in the small explosion chamber. The shock wave generated by the explosion enters the annular chamber and the annular distributor of the explosion combustion products through the injection channel, triggering a secondary explosion in the main reaction chamber and producing high-energy explosion products. The explosion products are ionized under the action of the electric field between the main reaction chamber wall and the conical electrode to generate a plasma jet, which is further heated and accelerated to form explosion products with plasma jets.

[0032] Step 8: The end of the rod-shaped metal anode is melted and vaporized by a high-energy plasma jet, and the vaporization products are mixed into the explosion products containing the plasma jet.

[0033] Step 9: The high-temperature, high-speed explosion products with plasma jet enter the nozzle. At the nozzle exit position, the compressed air introduced by the compressed air annular splitter further compresses and concentrates the energy. When passing through the oblique cut, the jet direction is deflected and reaches the workpiece surface to form a coating.

[0034] Step 10: During the continuous gas and powder supply process, the high-pressure pulse ignition device triggers an explosion at a set frequency, repeating the spraying process to achieve continuous coating preparation.

[0035] In a preferred embodiment of the present invention, in step 6, a 500-2000mF capacitor is connected to the power supply.

[0036] In a preferred embodiment of the present invention, in step 7, the electric field strength between the main reaction chamber wall and the conical electrode is 0–8 × 10⁻⁶. 5 The electric field strength is V / m, perpendicular to the direction of the explosive jet's movement, and varies along the length of the main reaction chamber, ranging from 0 to 8 × 10⁻⁶ V / m. 5 V / m, the electric field strength at the end of the reaction chamber is 0~4×10 5 V / m.

[0037] The beneficial effects of this invention are:

[0038] 1. In this invention, an electric field perpendicular to the direction of the explosive jet is formed between the main reaction chamber wall and the conical electrode. Under the action of the electric field, the explosion products are ionized to generate a plasma jet, which is further heated and accelerated to form explosion products with plasma jet, thereby increasing the energy of the combustion products and improving the coating performance.

[0039] 2. The present invention introduces a rod-shaped metal anode into the equipment. During the spraying operation, the end of the rod-shaped metal anode is melted and vaporized by a high-energy plasma jet, mixed with the explosion products of the plasma jet, and sprayed onto the surface of the workpiece. This can control the coating composition and achieve the effect of alloying.

[0040] 3. The nozzle outlet of the present invention is designed with a beveled cut. During spraying, a pressure difference is generated at the beveled cut position. The explosion shock wave is deflected under the action of the pressure difference at this position, thereby avoiding perpendicular injection of the workpiece. The reflected wave formed by the deflected powder jet will not collide with the incident wave, reducing energy loss, improving material utilization, and reducing the spraying distance to 30-60mm.

[0041] 4. The feeding chamber and diverter of the present invention are made of metal, making them easy to maintain and replace.

[0042] 5. In this invention, an electric field perpendicular to the direction of the explosive jet is formed between the main reaction chamber wall and the conical electrode. Under the action of the electric field, the explosion products are ionized to generate a plasma jet. The plasma jet is compressed and focused towards the center of the chamber under the action of the electric field, which increases the energy density at the center of the chamber while reducing the energy of the sidewall of the chamber, thereby reducing the risk of ablation of the sidewall of the chamber and improving the service life of the equipment.

[0043] 6. The inner wall of the nozzle of the present invention is also subject to an electric field, which reduces the energy impact on its inner wall surface, thereby reducing the risk of inner wall ablation and improving service life.

[0044] 7. The powder and gas continuously fed into the reaction chamber in this invention can be accurately measured using an advanced metering device. When the combustible gas explodes and burns, the pressure generated by the combustion products in the reaction chamber can reach 10 MPa, which is greater than the external gas-powder mixture feeding pressure. At this time, the gas and powder are stored in the distributor. When the combustion products and gas-powder mixture are ejected from the nozzle, the pressure in the reaction chamber drops, and the powder feeding channel can send the gas-powder mixture back into the feeding chamber. The higher the spraying frequency, the more accurate the powder feeding amount per pulse, the more uniformly the powder is heated and accelerated, and the higher the quality of the coating obtained. Attached Figure Description

[0045] Figure 1 This is a longitudinal sectional view of the spraying device of the present invention;

[0046] Explanation of reference numerals in the attached drawings: 1. Rod-shaped metal anode; 2. Anode conductive block; 3. Copper tube; 4. Insulator; 5. First cooling gas channel; 6. Second cooling gas channel; 7. First combustible gas inlet; 8. Second combustible gas inlet; 9. Small explosion chamber; 10. Spark plug; 11. Injection channel; 12. Annular chamber; 13. Annular distributor for explosion and combustion products; 14. Third combustible gas channel; 15. Powder feeder; 16. Powder feeding channel; 17. Nozzle; 18. Annular distributor for compressed air; 19. Bevel; 20. Coating; 21. Workpiece; 22. Feeding chamber; 23. Annular distributor for gas-powder mixture; 24. Copper tube end; 25. Main reaction chamber wall; 26. Main reaction chamber; 27. Conical electrode; 28. Fourth combustible gas channel; 29. ​​Annular distributor for combustible gas; 30. Cathode conductive block; 31. Annular distributor for cooling gas; 32. Power supply; 33. Gas control system; 34. Power control system; 35. Ignition device. Detailed Implementation

[0047] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0048] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0049] See Figure 1 , is a longitudinal cross-sectional view of the spraying device according to an embodiment of the present invention;

[0050] An electric field-assisted explosive spraying device includes: a rod-shaped metal anode 1, an anode conductive block 2, a copper tube 3, an insulator 4, a first cooling gas channel 5, a second cooling gas channel 6, a first combustible gas inlet 7, a second combustible gas inlet 8, a small explosion chamber 9, a spark plug 10, a spray channel 11, an annular chamber 12, an annular distributor for explosion and combustion products 13, a third combustible gas channel 14, a powder feeder 15, a powder feeding channel 16, a spray pipe 17, an annular distributor for compressed air 18, a beveled cut 19, a coating 20, a workpiece 21, a feeding chamber 22, and a gas-powder system. The system includes a mixture annular distributor 23, copper tube end 24, main reaction chamber wall 25, main reaction chamber 26, conical electrode 27, combustible gas fourth channel 28, combustible gas annular distributor 29, cathode conductive block 30, cooling gas annular distributor 31, power supply 32, gas control system 33, power control system 34, and ignition device 35; wherein, the small explosion chamber 9 is connected to the main reaction chamber 26 through the injection channel 11, annular chamber 12, and explosion combustion product annular distributor 13; wherein, the annular chamber 12 and the main reaction chamber 26 are equipped with a water cooling system.

[0051] The small explosion chamber 9 is equipped with a first combustible gas inlet 7, a second combustible gas inlet 8, and a spark plug 10; the upper part of the main reaction chamber 26 is equipped with a third combustible gas channel 14, a combustible gas annular distributor 29, and a fourth combustible gas channel 28; the lower part of the main reaction chamber 26 is equipped with a powder feeding channel 16, a gas-powder mixture annular distributor 23, and a feeding chamber 22; specifically, the feeding chamber 22 has a disc-shaped structure, and the feeding chamber 22 forms an annular cavity around the nozzle 17.

[0052] The powder feeding channel 16 is connected to the gas-powder mixture annular distributor 23, which is connected to the disc-shaped feeding chamber 22. The powder feeding channel 16 is connected to the powder feeder 15. A main reaction chamber wall 25 is formed on the outside of the main reaction chamber 26, and the main reaction chamber wall 25 is connected to the negative terminal of the power supply 32 through the cathode conductive block 30. A cooling gas annular distributor 31 is provided on the upper part of the insulator 4. The cooling gas enters the cooling gas annular distributor 31 through the second cooling gas channel 6, and then enters the interior of the insulator 4 for cooling. Conical structures are arranged along the axis of the main reaction chamber 26. The conical electrode 27 is fixed on the insulator 4. A copper tube 3 that can move along the axis of the conical electrode 27 is installed along the axis. A rod-shaped metal anode 1 is fixed inside the copper tube 3. The rod-shaped metal anode 1 extends from the end 24 of the copper tube to the tip of the conical electrode 27. The main reaction chamber wall 25 and the conical electrode 27 are energized to form an electric field perpendicular to the direction of the explosive jet. Under the action of the electric field, the explosion products are ionized to generate a plasma jet, which is further heated and accelerated to form explosion products with plasma jet, increasing the energy of the combustion products and improving the coating performance.

[0053] The rod-shaped metal anode 1 is connected to the copper tube 3 through the anode conductive block 2 and is connected to the positive terminal of the power supply 32; the negative terminal of the power supply 32 is connected to the workpiece 21; the rod-shaped metal anode 1 is introduced into the equipment, and during the spraying operation, the end of the rod-shaped metal anode 1 is melted and vaporized by the high-energy plasma jet, mixed into the explosion products of the plasma jet, and sprayed onto the surface of the workpiece, which can control the coating composition and achieve the effect of alloying.

[0054] A first cooling gas channel 5 is installed on the wall of the copper pipe 3 to deliver cooling gas into the copper pipe 3; a nozzle 17 is provided below the main reaction chamber 26, and the outlet of the nozzle 17 is configured with a beveled cut 19. A compressed air annular distributor 18 is provided at the outlet of the nozzle 17; the device is powered by a pulse control system 34, the gas and powder supply is controlled by a gas control system 33, and the spark plug is ignited by an ignition device 35. The high-voltage pulse frequency of the ignition device 35 is 2 to 15 Hz.

[0055] The nozzle 17 has a bevel 19 at its outlet, with a bevel angle of 25° to 60°. With this configuration, a pressure difference is generated at the bevel 19 during spraying. The explosion shock wave is deflected by this pressure difference, thus preventing perpendicular injection into the workpiece. The reflected wave formed by the deflected powder jet will not collide with the incident wave, reducing energy loss, improving material utilization, and reducing the spraying distance to 30 to 60 mm.

[0056] The feeding chamber 22, the explosion combustion product annular diverter 13, the compressed air annular diverter 18, the gas-powder mixture annular diverter 23, the combustible gas annular diverter 29, and the cooling gas annular diverter 31 are made of metal materials; they are easy to maintain and replace.

[0057] The outer wall of the conical electrode 27 has the same taper and is coaxial with the wall of the main reaction chamber 25. The main reaction chamber wall 25 and the conical electrode 27 are energized to form an electric field perpendicular to the direction of the explosive jet. Under the action of the electric field, the explosion products are ionized to generate a plasma jet. The plasma jet is compressed and focused towards the center of the chamber under the action of the electric field, which increases the energy density at the center of the chamber and reduces the energy of the sidewall of the chamber, thereby reducing the risk of ablation of the sidewall of the chamber and improving the service life of the equipment.

[0058] The rod-shaped metal anode 1 can be a solid rod or a flux-cored rod, which can be selected according to actual needs.

[0059] The inner wall of the nozzle 17 is also subjected to an electric field, which reduces the energy impact on its inner wall surface, thereby reducing the risk of inner wall ablation and improving service life; the distance from the outlet of the nozzle 17 to the workpiece 21 is 20-200mm, wherein the preferred distance in this embodiment is 30-60mm.

[0060] The powder feeding channel 16 is connected to the annular distributor 23 for the air-powder mixture, and the annular distributor 23 for the air-powder mixture is connected to the disc-shaped feeding chamber 22. The cross-sectional height of the feeding chamber 22 is 5 to 15 times the average particle size of the sprayed powder, and the outer diameter of the feeding chamber 22 is 60 to 80 mm larger than the diameter of the nozzle.

[0061] The small explosion chamber 9 is made of thermally conductive material and is equipped with an air cooling system. The annular chamber 12 and the main reaction chamber 26 are equipped with water cooling systems. The cooling gas supplied by the first cooling gas channel 5 is air. Air can be sent into the copper pipe 3.

[0062] In this embodiment, the powder and gas continuously fed into the reaction chamber can be precisely metered using advanced metering devices. When the combustible gas explodes and burns, the pressure generated by the combustion products in the reaction chamber can reach 10 MPa, which is greater than the external gas-powder mixture's inlet pressure. At this time, the gas and powder are stored in the distributor. When the combustion products and the gas-powder mixture are ejected from the nozzle, the pressure in the reaction chamber drops, and the powder feeding channel can send the gas-powder mixture back into the feeding chamber. The higher the spraying frequency, the more precise the powder feeding amount per pulse, the more uniformly the powder is heated and accelerated, and the higher the quality of the resulting coating.

[0063] A method for electric field-assisted explosive spraying includes the following steps:

[0064] Step 1: According to the design requirements of coating 20, select the material of rod-shaped metal anode 1, insert rod-shaped metal anode 1 into copper tube 3, determine the extension length of rod-shaped metal anode 1 at the tip of conical electrode 27, and fix it coaxially with copper tube 3 and conical electrode 27.

[0065] Step 2: Load an appropriate amount of coating 20 powder into the powder feeder 15;

[0066] Step 3: Set the flow rate of each powder delivery and gas delivery channel through the gas control system 33;

[0067] Step 4: Set the high-voltage pulse frequency of the ignition device 35 through the power control system 34, and set the spraying process specifications;

[0068] Step 5: Control the motion trajectory of workpiece 21 through the motion system;

[0069] Step 6: Open the solenoid valves of the first combustible gas inlet 7 and the second combustible gas inlet 8 to supply gas to the small explosion chamber 9; simultaneously, combustible gas is introduced into the main reaction chamber 26 through the third combustible gas channel 14, the combustible gas annular distributor 29, and the fourth combustible gas channel 28, and a gas-powder mixture is introduced into the main reaction chamber 26 through the powder feeding channel 16, the gas-powder mixture annular distributor 23, and the feeding chamber 22, where the combustible gas and the gas-powder mixture are compressed; connect the power supply 32 to form an electric field between the main reaction chamber wall 25 and the conical electrode 27; the first cooling gas channel 5 supplies cooling gas, and the second cooling gas channel 6 supplies inert gas;

[0070] Step 7: The ignition device 35 controls the spark plug 10 to ignite according to the set pulse frequency, and an explosion is generated in the small explosion chamber 9. The shock wave generated by the explosion enters the annular chamber 12 and the annular diverter 13 of the explosion combustion products through the injection channel 11, and triggers a secondary explosion in the main reaction chamber 26, generating high-energy explosion products. The explosion products are ionized under the action of the electric field between the main reaction chamber wall 25 and the conical electrode 27 to generate a plasma jet, and are further heated and accelerated to form explosion products with plasma jets.

[0071] Step 8: The end of the rod-shaped metal anode 1 is melted and vaporized by a high-energy plasma jet, and the vaporization products are mixed into the explosion products containing the plasma jet.

[0072] Step 9: The high-temperature, high-speed explosion products with plasma jet enter the nozzle 17. At the nozzle exit position, the compressed air introduced by the compressed air annular splitter 18 is further compressed and focused. When passing through the oblique cut 19, the jet direction is deflected and reaches the surface of the workpiece 21 to form a coating 20.

[0073] Step 10: During the continuous gas and powder supply process, the high-pressure pulse ignition device 35 triggers an explosion at a set frequency, repeating the spraying process to achieve continuous preparation of coating 20.

[0074] In step 6, power supply 32 is connected to a capacitor of 500-2000mF; in this embodiment, power supply 32 is connected to an 800mF capacitor.

[0075] In step 7, the electric field strength between the main reaction chamber wall 25 and the conical electrode 27 is 0–8 × 10⁻⁶. 5 The electric field strength is V / m, perpendicular to the direction of the explosive jet's movement, and extends along the length of the main reaction chamber 26. This electric field strength varies, ranging from 0 to 8 × 10⁻⁶ at the detonation point. 5 V / m, the electric field strength at the end of the reaction chamber is 0~4×10 5 V / m.

[0076] After the spraying operation, purge air can be introduced into the small explosion chamber 9 to purge the small explosion chamber 9, the main reaction chamber 26, and the nozzle 17.

[0077] The present invention will be described in more detail through several embodiments:

[0078] A series of experiments were conducted using the equipment and method described in this invention. Spraying was performed on 45# steel samples, and hardness and porosity tests were performed on the sprayed samples to verify the effectiveness of the method. Experimental specifications and results are shown in Table 1. The equipment was installed in a special enclosure and connected to a gas control system and a power control system. First, the effect of pure explosive spraying was tested; second, the effect of explosive spraying with an applied auxiliary electric field was tested.

[0079] Using spherical powder with a particle size of 50–63 μm, Fe was sprayed. 40 C 40 B 20 An alloy coating with a eutectic composition. Using the apparatus and method described in this invention, gas and powder are continuously supplied via a gas control system. An electrostatic field is generated between the electrodes in the reaction chamber using a 30kW inductive-capacitor power supply.

[0080] Example 1:

[0081] Propane and oxygen were fed into a small explosion chamber at a flow ratio of 1:5. Explosion frequencies of 2Hz, 5Hz, and 10Hz were used, each corresponding to a different volumetric composition of the mixture. Powder utilization was determined by weighing.

[0082] Table 1 shows the measurement results of powder utilization rate. The highest powder utilization rate, reaching 70%, was achieved at an explosion frequency of 10 Hz, as shown in items 1-4 of Table 1. At an explosion frequency of 10 Hz, the propane gas flow rate was 0.9 m³ / s. 3 / h, oxygen flow rate is 4.5m 3 / h, air flow rate is 5m 3 The powder feeding rate is 5.4 kg / h. The nozzle outlet bevel angle is 45°.

[0083] Example 2:

[0084] This embodiment is similar to Embodiment 1, except that the explosion frequency is set to a constant 10Hz, and the combustible gas flow rate is set as follows: propane flow rate is 0.9m³ / h. 3 / h, oxygen flow rate is 4.5m 3 / h, air flow rate is 5m 3The powder feeding rate was 5.4 kg / h. The effects of the nozzle exit bevel angle and spraying distance on the coating effect were studied. Bevel angles were 0°, 15°, 30°, 45°, 60°, and 75°, and spraying distances were 40 mm and 100 mm. Powder utilization, coating porosity, and coating adhesion were tested. The experimental results are shown in items 5-15 of Table 1.

[0085] The results show that the coating exhibits the best porosity and adhesion when the bevel angle is 45°. As the distance increases, the energy of the sprayed powder decreases, thus increasing porosity and decreasing adhesion.

[0086] Powder utilization reaches 70% when spraying over short distances. When the spraying distance increases to 100mm, the bevel angle no longer affects the coating performance, but the powder utilization rate decreases to 20-40%.

[0087] Example 3:

[0088] This embodiment is similar to Embodiment 1, except that the explosion frequency is set to a constant 10Hz, and the combustible gas flow rate is set as follows: propane flow rate is 0.9m³ / h. 3 / h, oxygen flow rate is 4.5m 3 / h, air flow rate is 0m³ / h 3 The powder feeding rate was 5.4 kg / h. The bevel angle at the nozzle exit was 45°, and the spraying distance was 40 mm. The test results are shown in item 16 of Table 1.

[0089] Example 4:

[0090] This embodiment is similar to Embodiments 1 and 3, except that the flow rate of the combustible gas is changed, and the flow rate of the combustible gas and the powder feeding speed are increased proportionally.

[0091] The results showed that as the flow rate of combustible gas increased, the gas pressure and density also increased accordingly. To completely fill the reaction chamber, the consumption rate of combustible gas and sprayed powder doubled, leading to a decrease in coating quality. These experimental results are shown in items 17–21 of Table 1.

[0092] Increasing the flow rate of compressed air and combustible gas without changing the powder feeding speed can improve the quality of the coating, as shown in items 22 to 25 of Table 1.

[0093] Example 5:

[0094] In this embodiment, the gas flow rate, explosion frequency, and powder feeding speed are maintained, the bevel angle at the nozzle exit is kept constant at 45°, and the spraying distance is adjusted to 20-140mm.

[0095] The test results show that the coating quality is best when the spraying distance is 30-60 mm. As the distance increases, the coating quality decreases, as shown in items 26-33 of Table 1.

[0096] Example 6:

[0097] In this embodiment, the explosion frequency is maintained at 10Hz, and the gas flow rates are as follows: propane 1.0m³ / h. 3 / h, oxygen 5.0m 3 / h, air 6.0m 3 / h. The difference is that an inductor-capacitor power supply is connected to the electrodes of the reaction chamber, generating an electrostatic field with energy of 3000-6000J in the reaction chamber.

[0098] Keeping the electrostatic field energy constant at 3000J, the powder feeding speed was increased from 8.0kg / h to 16kg / h. The results are shown in items 34 to 38 of Table 1. When the powder feeding speed exceeds 12kg / h, the quality of the coating drops sharply.

[0099] The powder feeding rate was adjusted to 10 kg / h, and the electric field was gradually increased. The results are shown in items 39-42 of Table 1. When the electric field energy increased to 4000 J, the coating quality improved. However, when the electric field energy increased to 6000 J, the adhesion of the coating to the substrate decreased sharply, and the porosity of the coating increased. The reason for the sharp decline in coating quality is that the increased discharge energy caused the dispersed particles to overheat and become too fast. The excessively fast particles caused splashing when they collided with the workpiece.

[0100] According to Table 1, the analysis of the test results for all embodiments shows that even in the pure explosion mode, the coating quality and productivity of the sprayed coating are at a high level. Adding an auxiliary electric field significantly increases the proportion of nanocrystalline and amorphous phases in the coating, significantly reduces porosity, achieves an adhesion strength of 250 MPa, and significantly improves hardness. Furthermore, the powder utilization rate can reach over 75% after adding the auxiliary electric field. Therefore, the equipment and method of this invention significantly improve the coating quality, reduce powder consumption, and save on the consumption of combustible gas mixtures. The use of an electric field-assisted method alters the coating formation mechanism, resulting in a nanocrystalline and amorphous phase ratio of up to 100% in the sprayed material. A diffusion process exists at the interface between the coating and the substrate, which determines the high adhesion between the coating material and the substrate. The optimal effect of the coating prepared by the assisted electric field explosion spraying mode is shown in items 40 and 41 of Table 1.

[0101] Table 1 Spraying Fe 40 C 40 B 20 Coating process specifications and experimental results

[0102]

[0103]

[0104] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention; therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

[0105] Although this paper uses many of the figure references: rod-shaped metal anode 1, anode conductive block 2, copper tube 3, insulator 4, first cooling gas channel 5, second cooling gas channel 6, first combustible gas inlet 7, second combustible gas inlet 8, small explosion chamber 9, spark plug 10, injection channel 11, annular chamber 12, annular distributor for explosion and combustion products 13, third combustible gas channel 14, powder feeder 15, powder feeding channel 16, nozzle 17, annular distributor for compressed air 18, oblique cut 19, coating 20, workpiece 21, feeding chamber 22, annular distributor for gas-powder mixture 23, copper tube end 24, main reaction chamber wall 25, main reaction chamber 26, conical electrode 27, fourth combustible gas channel 28, annular distributor for combustible gas 29, cathode conductive block 30, annular distributor for cooling gas 31, power supply 32, gas control system 33, power control system 34, ignition device 35, etc., the possibility of using other terms is not excluded. The use of these terms is merely for the convenience of describing and explaining the nature of the invention; interpreting them as any additional limitation would be contrary to the spirit of the invention.

Claims

1. An electric field-assisted explosive spraying device, characterized in that: It includes an insulator (4), a small explosion chamber (9), and a main reaction chamber (26); the small explosion chamber (9) is connected to the main reaction chamber (26) through an injection channel (11), an annular chamber (12), and an annular distributor for explosion and combustion products (13); the small explosion chamber (9) is provided with a first combustible gas inlet (7), a second combustible gas inlet (8), and a spark plug (10); the upper part of the main reaction chamber (26) is provided with a third combustible gas channel (14), a combustible gas annular distributor (29), and a fourth combustible gas channel (28); the lower part of the main reaction chamber (26) is provided with a powder feeding channel (16) and a gas-powder feeding channel. A mixture annular splitter (23) and a feeding chamber (22); the powder feeding channel (16) is connected to the gas-powder mixture annular splitter (23), and the gas-powder mixture annular splitter (23) is connected to the disc-shaped feeding chamber (22); the powder feeding channel (16) is connected to the powder feeder (15); a main reaction chamber wall (25) is formed on the outside of the main reaction chamber (26), and the main reaction chamber wall (25) is connected to the negative terminal of the power supply (32) through the cathode conductive block (30); a cooling gas annular splitter (31) is provided on the upper part of the insulator (4), and the cooling gas enters the cooling gas annular splitter (31) through the second cooling gas channel (6). 1), and then enter the insulator (4) for cooling; a conical electrode (27) is arranged along the axis of the main reaction chamber (26), and the conical electrode (27) is fixed on the insulator (4); a copper tube (3) that can move along the axis is installed along the axis of the conical electrode (27), and a rod-shaped metal anode (1) is fixed inside the copper tube (3). The rod-shaped metal anode (1) extends from the end (24) of the copper tube and the tip of the conical electrode (27). The rod-shaped metal anode (1) is connected to the copper tube (3) through the anode conductive block (2) and connected to the positive terminal of the power supply (32); the negative terminal of the power supply (32) is connected to the workpiece (21); copper The wall of the tube (3) is equipped with a first cooling gas channel (5) that can send cooling gas into the copper tube (3); a nozzle (17) is provided below the main reaction chamber (26), the outlet of the nozzle (17) is configured with a slanted cut (19), and a compressed air annular distributor (18) is provided at the outlet of the nozzle (17); it also includes a gas control system (33), a power control system (34) and an ignition device (35); wherein, the device controls pulse power supply through the power control system (34), controls gas and powder supply through the gas control system (33), and controls spark plug ignition through the ignition device (35).

2. The electric field-assisted explosive spraying equipment according to claim 1, characterized in that: The nozzle (17) has a bevel (19) at its outlet position, and the bevel angle of the bevel (19) is 25° to 60°.

3. The electric field-assisted explosive spraying equipment according to claim 1, characterized in that: The outer wall of the conical electrode (27) has the same taper and is coaxial with the wall of the main reaction chamber (25).

4. The electric field-assisted explosive spraying equipment according to claim 1, characterized in that: The rod-shaped metal anode (1) is a solid rod.

5. The electric field-assisted explosive spraying equipment according to claim 1, characterized in that: The rod-shaped metal anode (1) is a core rod.

6. The electric field-assisted explosive spraying equipment according to claim 1, characterized in that: The feeding chamber (22) has a disc-shaped structure, and the feeding chamber (22) forms an annular cavity around the nozzle (17).

7. The electric field-assisted explosive spraying equipment according to claim 1, characterized in that: The feeding chamber (22), the explosion combustion product annular splitter (13), the compressed air annular splitter (18), the gas-powder mixture annular splitter (23), the combustible gas annular splitter (29), and the cooling gas annular splitter (31) are made of metallic materials.

8. The electric field-assisted explosive spraying equipment according to claim 1, characterized in that: The cross-sectional height of the feeding chamber (22) is 5 to 15 times the average particle size of the sprayed powder.

9. The electric field-assisted explosive spraying equipment according to claim 1, characterized in that: The outer diameter of the feeding chamber (22) is 60-80 mm larger than the diameter of the nozzle (17).

10. The electric field-assisted explosive spraying equipment according to claim 1, characterized in that: The annular chamber (12) and the main reaction chamber (26) are equipped with water cooling systems.

11. The electric field-assisted explosive spraying equipment according to claim 1, characterized in that: The high-voltage pulse frequency of the ignition device (35) is 2 to 15 Hz.

12. The electric field-assisted explosive spraying equipment according to claim 1, characterized in that: The distance from the outlet of the nozzle (17) to the workpiece (21) is 20 to 200 mm.

13. A method for electric field-assisted explosive spraying, characterized in that: Includes the following steps: Step 1: According to the design requirements of the coating (20), select the material of the rod-shaped metal anode (1), insert the rod-shaped metal anode (1) into the copper tube (3), determine the extension length of the rod-shaped metal anode (1) at the tip of the conical electrode (27), and fix it coaxially with the copper tube (3) and the conical electrode (27); Step 2: Load an appropriate amount of coating (20) powder into the powder feeder (15); Step 3: Set the flow rate of each powder delivery and gas delivery channel through the gas control system (33); Step 4: Set the high voltage pulse frequency of the ignition device (35) through the power control system (34) and set the spraying process specifications; Step 5: Control the motion trajectory of the workpiece (21) through the motion system; Step 6: Open the solenoid valves of the first combustible gas inlet (7) and the second combustible gas inlet (8) to supply gas to the small explosion chamber (9); at the same time, combustible gas is introduced into the main reaction chamber (26) through the third combustible gas channel (14), the combustible gas annular distributor (29) and the fourth combustible gas channel (28), and a gas-powder mixture is introduced into the main reaction chamber (26) through the powder feeding channel (16), the gas-powder mixture annular distributor (23) and the feeding chamber (22). The combustible gas and the gas-powder mixture are compressed in the main reaction chamber (26); turn on the power supply (32) to form an electric field between the main reaction chamber wall (25) and the conical electrode (27); the first cooling gas channel (5) supplies cooling gas and the second cooling gas channel (6) supplies inert gas. Step 7: The ignition device (35) controls the spark plug (10) to ignite according to the set pulse frequency, and an explosion is generated in the small explosion chamber (9). The shock wave generated by the explosion enters the annular chamber (12) and the annular diverter (13) of the explosion combustion products through the injection channel (11), and triggers a secondary explosion in the main reaction chamber (26), generating high-energy explosion products. The explosion products are ionized under the action of the electric field between the main reaction chamber wall (25) and the conical electrode (27) to generate a plasma jet, and are further heated and accelerated to form an explosion product with a plasma jet. Step 8: The end of the rod-shaped metal anode (1) is melted and vaporized by a high-energy plasma jet, and the vaporization products are mixed into the explosion products with plasma jet. Step 9: The high-temperature and high-speed plasma jet explosion products enter the nozzle (17). At the nozzle exit position, the compressed air introduced by the compressed air annular splitter (18) is further compressed and focused. When passing through the oblique cut (19), the jet direction is deflected and reaches the surface of the workpiece (21) to form a coating (20). Step 10: During the continuous gas and powder delivery process, the high-pressure pulse ignition device (35) triggers an explosion at a set frequency, repeating the spraying process to achieve continuous preparation of the coating (20).

14. The method for electric field-assisted explosive spraying according to claim 13, characterized in that: In step 6, the power supply (32) is connected to a capacitor of 500-2000mF.

15. The method for electric field-assisted explosive spraying according to claim 13, characterized in that: In step 7, the electric field strength between the main reaction chamber wall (25) and the conical electrode (27) is 0–8 × 10⁻⁶. 5 V / m, the electric field direction is perpendicular to the direction of movement of the explosive jet, along the length of the main reaction chamber (26), the electric field strength is variable, the electric field strength at the detonation point is 0~8×10 5 V / m, the electric field strength at the end of the reaction chamber is 0~4×10 5 V / m.

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