Metal surface plasma detonation treatment device

Abstract

The application discloses a metal part plasma detonation treatment device, which comprises a capacitive induction power supply, a reaction chamber and a detonation gun. The capacitive induction power supply comprises a ring-shaped cathode electrode, a ring-shaped anode electrode and a center electrode. The center electrode is fixedly connected with the anode electrode. The reaction chamber is a ring-shaped cavity surrounding the anode electrode. The reaction chamber separates the cathode electrode from the anode electrode. The detonation gun is connected with a detonation gun ring chamber and is used for introducing combustible gas and performing periodic detonation. The nozzle is connected with the ring-shaped cavity and is used for introducing alloy elements. The metal part plasma detonation treatment device improves the hardening effect of the device on the metal surface, improves the uniform distribution of the alloy elements, and improves the modification quality and productivity of the workpiece surface.

Description

Technical Field

[0001] This invention belongs to the field of materials processing, specifically relating to a device for plasma detonation treatment of metal surfaces. Background Technology

[0002] A high-voltage plasma device is known (RU PATENT 2 529 056 C2, IPC H05H 1 / 26 (2006.01). Publication date: September 27, 2014, Publication No. 27). The high-voltage plasma device consists of a high-voltage power supply, a plasma generator, a conical nozzle, circular ignition and output electrodes, a central insulating washer with holes parallel to the axis, and insulating washers with holes inclined to the device axis. Additionally, a fan is provided for axial air supply.

[0003] This invention utilizes plasma technology to heat and treat the surface of metal parts using various gases. Its technological achievements include improved device efficiency and extended service life of the working electrodes. In continuous mode, a high-voltage power supply generating a high-frequency AC voltage is connected to a conical nozzle and two circular electrodes, one for ignition and the other for output. The two circular electrodes are coaxially mounted within a circular insulator (i.e., the main body of the device) via a central insulating washer. The hole in the central insulating washer is parallel to the device's main shaft, allowing air to enter.

[0004] The high-voltage plasma device operates as follows: Turning on the high-voltage power supply triggers a high-voltage discharge from the tip of the ignition electrode to the bottom of the conical nozzle, generating an electric arc in the narrow gap between them. A fan is activated, blowing air in through an inclined hole in the insulating gasket, and the airflow rotates around the conical nozzle. The translational-rotational motion of the airflow carries the electric arc to the edge of the conical nozzle, whereupon the airflow propels the arc out as plasma through the nozzle's inner orifice. The orifice in the insulating gasket provides additional airflow for cooling the structural components of the plasma device and contributes to the stability of the plasma jet shape.

[0005] The main drawback of this known device is the low power of the plasma jet. Due to limitations in the structure of the plasma device, the electrode surface experiences accelerated ablation as the current increases. This plasma device cannot be used for rapid heating of the workpiece surface in the serialized, mass production of metal parts.

[0006] A device for plasma hardening steel and cast iron parts using dual-arc plasma in automatic and manual modes is known, RU Patent 95,665U1, IPC C21D1 / 09 (2006.01). Publication date: July 10, 2010, Gazette No. 19.

[0007] The plasma hardening apparatus consists of a working gas supply system, an insulator, and a cathode assembly. The plasma accelerator has a nozzle using a ferromagnetic jaw scanning device, structurally integrated into a small plasma accelerator. It also includes devices for fixing, rotating, and adjusting the plasma accelerator during operation, as well as a cooling system for the nozzle and the ferromagnetic jaw nozzle. The plasma accelerator incorporates an arc scanning device, including a generator, electromagnetic coils, a ferromagnetic sponge, a control panel with a built-in oscillator and measuring instruments. The induction coil has an AC voltage potential indicator and a DC voltage regulator. Hardening is achieved by moving the dual-arc plasma accelerator above the surface of the metal workpiece, with the burning arcs acting directly and indirectly on the workpiece surface. In this plasma accelerator, each arc is powered by a separate rectifier, and the electrical power of each arc can be individually adjusted.

[0008] The drawbacks of this known device are low power, slow velocity, and low kinetic energy of the plasma jet. The technical parameters of the resulting plasma jet are insufficient to form a sufficiently thick (up to 50 μm) nanocrystalline layer on the workpiece surface.

[0009] A known method and apparatus for plasma explosion processing of metal products. European Patent, Application No.: 91907287.6INT.cl.5:C23C 4 / 00,B05B7 / 20. Publication No.:0531527A1.

[0010] According to this invention, the pulsed plasma generator has two combustion chambers—a reaction chamber and a detonation chamber—filled with a mixture of combustible gases and powdered materials of metals from Groups III, IV, V, and VI of the periodic table. A spark plug is fixed in the detonation combustion chamber and can periodically ignite the combustible mixture at the gas mixture. In the reaction chamber, the detonation combustion mode takes place in an electromagnetic field generated by the conversion current of the combustion products. This invention processes metal surfaces using a high-energy jet of combustion products and powdered materials. Simultaneously, the powdered materials and plasma compounds are deposited on the metal surface. Due to rapid heating and cooling, recrystallization and dispersion alloying occur on the metal surface. This device can be used to harden the worn surfaces of mechanical parts and tools.

[0011] The disadvantages of this invention are that using powder materials to modify the workpiece surface alters its geometric parameters. Furthermore, the modified surface is heated using plasma jet heating, and the heating rate is limited due to the convection mechanism of the heat transfer medium. Therefore, the heating and cooling rates of the workpiece surface are insufficient for recrystallization and the formation of nanocrystalline materials. Uneven introduction of combustion products in the reaction chamber leads to uneven discharge in the electrode gap, resulting in localized ablation of the electrode surface. The uneven input of plasma jets contaminated with corrosion products and current creates an asymmetric jet, which forms corresponding combustion product impact compression zones on the metal workpiece surface. Ultimately, an uneven, rapidly hardened layer forms on the workpiece surface. The device is inefficient, and surfaces processed using it require grinding to ensure the required roughness and precision, which is another reason limiting its use.

[0012] Therefore, improvements are needed to address the aforementioned technical issues. Summary of the Invention

[0013] To address the shortcomings of existing technologies, this invention provides a plasma detonation treatment device for metal parts, which improves the hardening effect of such devices on metal surfaces, enhances the uniform distribution of alloying elements, and improves the modification quality and productivity of workpiece surfaces.

[0014] To achieve the above objectives, the technical solution adopted in this invention is: a plasma detonation treatment device for metal components, comprising: a capacitive induction power supply, wherein the capacitive induction power supply is connected to a cathode electrode and a central electrode respectively via a first current lead and a second current lead, and the central electrode is fixedly connected to an anode electrode; a reaction chamber, wherein the reaction chamber includes an annular chamber and a conical chamber surrounding the anode electrode, and is composed of a cavity between the anode electrode and the cathode electrode, separating the cathode electrode from the anode electrode; a detonation gun, wherein the detonation gun is connected to the detonation gun annular chamber and is used to introduce combustible gas and perform periodic detonation; a nozzle, wherein the nozzle is connected to the annular chamber and is used to introduce one or more elements of groups III, IV, V, and VI of the periodic table and their compounds into the annular chamber; a consumable electrode, wherein the consumable electrode is fixed on the axis of the central electrode and the anode electrode and penetrates the anode electrode, and is used to provide alloying elements; a cooling chamber is provided between the consumable electrode and the anode electrode, and the cooling chamber separates the consumable electrode from the anode electrode.

[0015] As a preferred embodiment of the present invention, the explosive gun is provided with a combustible gas inlet, an oxygen inlet, and an electric spark plug; the electric spark plug is connected to an auxiliary pipe through an angle concentrator, and periodically discharges to ignite the combustible gas mixture.

[0016] In a preferred embodiment of the present invention, the angle concentrator on the explosive gun is connected to the explosive gun annular chamber via an auxiliary pipe.

[0017] As a preferred embodiment of the present invention, the explosive gun annular chamber is divided into two identical chambers, upper and lower, which are connected by a smooth connector. An auxiliary tube is tangentially input to the end of the upper annular chamber and the front end of the lower annular chamber of the explosive gun.

[0018] As a preferred embodiment of the present invention, the nozzle is tangentially connected to the annular distributor in the lower annular chamber of the explosive gun. Small holes are evenly distributed on the circumference of the annular distributor, and a corner reflector installed on each hole is connected to the annular chamber to uniformly supply the explosion and combustion products to the annular chamber. One or more elements of Groups III, IV, V, and VI of the periodic table and their compounds (using hydrocarbon gas or nitrogen carrier gas to transport powder, etc.) are uniformly introduced into the reaction chamber.

[0019] In a preferred embodiment of the present invention, the total cross-sectional area of ​​the corner reflector is smaller than the total cross-sectional area of ​​the explosive gun annular chamber.

[0020] In a preferred embodiment of the present invention, the explosive gun annular chamber, the annular cavity, the anode electrode, and the center electrode are coaxially arranged.

[0021] In a preferred embodiment of the present invention, a first annular insulator and a second annular insulator are further provided between the cathode electrode and the anode electrode; an annular connector is assembled between the first annular insulator and the second annular insulator.

[0022] In a preferred embodiment of the present invention, the cooling chamber is composed of a cavity between the consuming electrode and the inner wall of the anode. The cooling gas flow entering the cooling chamber through the cooling gas inlet is concentrated along the inner wall of the anode to the end of the electrode for cooling the consuming electrode.

[0023] As a preferred embodiment of the present invention, a cathode outlet end is formed at the bottom of the cathode electrode, and a plasma jet for impacting the workpiece surface is formed between the cathode outlet end and the electrode end.

[0024] As a preferred embodiment of the present invention, the electrode end of the consumable electrode can be compensated for by axial movement when it is consumed, and it is cooled by airflow.

[0025] As a preferred embodiment of the present invention, the alloying elements are placed on the inner surface of the reaction chamber in the form of a recyclable coating, which can be re-prepared by methods such as thermal spraying after consumption.

[0026] The present invention has the following beneficial effects:

[0027] 1. This invention improves the hardening effect of the metal surface, enhances the uniform distribution of alloying elements, and improves the modification quality and productivity of the workpiece surface by setting up a plasma detonation treatment device for metal parts.

[0028] 2. The metal component plasma detonation treatment apparatus of the present invention can increase the frequency of pulsed plasma generation. By uniformly supplying the explosion and combustion products to the annular chamber through 10 to 15 corner reflectors connected to the annular chamber, the energy conversion of the current on the electrode surface is uniformly distributed, which can ensure a corresponding reduction in energy density and at the same time reduce the erosion intensity of the electrode surface; the frequency of pulsed plasma generation is increased by 5 to 10 times.

[0029] 3. This invention increases the uniformity of alloy element distribution in the reaction chamber and plasma jet; it expands the application range of the device and can form a nanocrystalline layer on the working surface of metal parts. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the metal component plasma detonation treatment device of the present invention;

[0031] Figure 2 This is a schematic diagram showing the flow direction and energy conversion of explosion and combustion products in the plasma detonation treatment device for metal components of the present invention;

[0032] Figure 3 This is the invention. Figure 2 AA section view;

[0033] Figure 4 This is the invention. Figure 2 BB section view;

[0034] Figure 5 This is a schematic diagram of the energy conversion between the consumable electrode and the workpiece surface of the plasma detonation treatment apparatus for metal parts according to the present invention.

[0035] Explanation of reference numerals in the attached drawings: 1. Center electrode; 2. Consumable electrode; 3. Cooling gas inlet; 4. Screw; 5. Explosion gun; 6. Combustible gas inlet; 7. Oxygen inlet; 8. Spark plug; 9. Angle concentrator; 10. Auxiliary pipe; 11. Nozzle; 12. Angle reflector; 13. Anode electrode; 14. Conical chamber; 15. Anode inner wall; 16. Electrode end; 17. Cathode outlet end; 18. Annular chamber; 19. Annular distributor; 20. Smooth connector; 21. Explosion gun annular chamber; 22. First annular insulator; 23. Annular connector; 24. Second annular insulator; 25. First current lead; 26. Second current lead; 27. Workpiece; 28. Impact compression layer; 29. ​​Plasma jet; 30. Detailed Implementation

[0036] 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.

[0037] 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.

[0038] This invention relates to a plasma detonation treatment device for metal components, comprising: a capacitive induction power supply, which is connected to a cathode electrode 14 and a central electrode 1 respectively via a first current lead 26 and a second current lead 27, the central electrode 1 being fixedly connected to an anode electrode 13; a reaction chamber, which includes an annular chamber 19 surrounding the anode electrode and a conical chamber 15, formed by a cavity between the anode electrode 13 and the cathode electrode 14, separating the cathode electrode 14 and the anode electrode 13; a detonation gun 5, which is connected to a detonation gun annular chamber 22 and is used to introduce combustible gas and perform periodic detonation; a nozzle 11, which is connected to the annular chamber 19 and is used to introduce one or more elements of groups III, IV, V, and VI of the periodic table and their compounds into the annular chamber; a consumable electrode 2, which is fixed on the axis of the central electrode 1 and the anode electrode 13 and passes through the anode electrode 13, and is used to provide alloying elements; a cooling chamber is provided between the consumable electrode 2 and the anode electrode 13, the cooling chamber separating the consumable electrode 2 from the anode electrode 13.

[0039] The explosion gun annular chamber 22 is divided into two identical chambers, upper and lower. The explosion gun annular chamber 22, annular chamber 19, anode electrode 13, and center electrode 1 are coaxially arranged. The auxiliary pipe 10 is tangentially input to the end of the upper annular chamber and the front end of the lower annular chamber of the explosion gun, which ensures the development of the explosion combustion mode. The corner reflectors 12, which are evenly distributed along the circumference of the lower annular chamber of the explosion gun, have a total cross-sectional area lower than that of the explosion gun annular chamber, which ensures a uniform supply of explosion combustion products to the reaction chamber annular chamber 19.

[0040] A rod-shaped consumable electrode 2 is installed along the axial direction of the reaction chamber to provide alloying elements. The electrode tip 17 can be compensated for axial movement when consumed, and is cooled by airflow. The alloying elements can also be tangentially input into the lower annular chamber of the explosive gun through nozzle 11 and introduced into the annular chamber 19 of the reaction chamber via an annular distributor 20 and corner reflector 12. The alloying elements can also be applied to the inner surface of the reaction chamber in the form of a regenerable coating. After the coating material is consumed, it can be re-prepared by thermal spraying.

[0041] Nozzle 11 is connected to an annular chamber 19. One or more elements of groups III, IV, V, and VI of the periodic table or their compounds are tangentially input into the annular distributor 20 of the lower annular chamber of the explosive gun through nozzle 11, and communicate with the annular chamber 19 through circumferentially distributed holes in the annular distributor 20 and corner reflectors 12 connected thereto.

[0042] The consumable electrode 2 is fixed on the axis of the central electrode 1 and cooled by the cooling gas flow from the cooling gas inlet 3. The cooling gas flow flows out along the inner wall 16 of the anode, which concentrates the cooling gas flow to the electrode end 17. The bottom of the cathode electrode 14 is the cathode outlet end 18, and a plasma jet 30 for impacting the surface of the workpiece 28 is formed between the electrode end 17 and the cathode outlet end 18. Each impact of the pulsed plasma on the surface of the workpiece 28 is accompanied by a current impact. The synthesis product and the workpiece surface are periodically and rapidly heated to above the phase transition temperature and then cooled by the plasma. The rapid heating and cooling of the workpiece surface is carried out simultaneously with the impact of the pulsed current, magnetic field, acoustic field impact, and vibration. The pulsed current intensity is 10 × 10⁻⁶. 7 A / m 2 The magnetic field strength is 4 × 10 5 A / m, sound pressure range of 140~150dB, vibration frequency of 20000Hz.

[0043] The capacitive sensing power supply is connected to the circuit via the first current lead 26 and the second current lead 27. This device is equipped with a capacitive sensing current memory, and the electrode polarity of the device is switched at a frequency of 1–5 Hz by the conductive products of the explosive combustion. During the current commutation gap, a plasma compound layer formed by plasma elements and consuming electrode elements condenses on the workpiece surface. During each plasma pulse, this plasma compound periodically melts and bonds to the substrate. Furthermore, the current is switched through the pulsed plasma in the gap between the end of the consuming electrode and the hardened surface.

[0044] The structural features of the plasma detonation device can increase the power of the plasma jet. A current of 4000–6000 A along the plasma jet will generate a corresponding pulsed magnetic field. Injecting metal vapor and combustible gas into the pulsed plasma can increase its conductivity and improve the efficiency of plasma chemical synthesis and the deposition efficiency of the synthesis products on the workpiece surface. Metal vapor can be injected into the plasma from the consumable electrode.

[0045] This plasma pulse energy can rapidly heat the surface and create a high temperature gradient. This high-gradient heating of the localized surface causes elastoplastic deformation, refines the grain size of the surface material, and enhances the surface diffusion process.

[0046] Plasma detonation treatment generates intense acoustic vibrations, which activate phonons and phonon-electron interactions in the metal workpiece, thereby increasing the metal's thermal conductivity and temperature gradient. Ultimately, plasma detonation treatment provides effective elastoplastic deformation and nanocrystal formation. Pulsed magnetic fields can activate magnons, which function similarly to phonons.

[0047] The device injects metallic elements and gases from the consumable electrode into a plasma. These elements form superheated vapors of compounds that are deposited on the workpiece surface during current commutation intervals. Subsequent plasma pulses melt the deposited layer along with the substrate surface and perform complex alloying on the workpiece surface. The consumable electrode is made from various powders using powder metallurgy or other alloying methods.

[0048] The aforementioned key features of the plasma detonation treatment apparatus enable the formation of high-quality nanocrystalline layers on the surface of metal workpieces. This apparatus reduces the consumption of alloying elements and lowers the cost of coating preparation (compared to the prototype apparatus).

[0049] A combustible gas mixture is filled into the reaction chamber and electrode gap of the device, and an explosive combustion mode is periodically initiated. The combustion products are converted into current pulses in the reaction chamber. Finally, impact pulses, acoustic pulses, and magnetic pulses from a magnetic field act together on the workpiece surface. The current switches between the consuming electrode tip and the hardened surface via pulsed plasma.

[0050] The workpiece surface simultaneously generates elastoplastic vibration, acoustic vibration, and magnetic vibration. A consumable electrode is mounted along the axis of the device, enriching the plasma with alloying elements participating in the plasma chemical synthesis process, forming corresponding plasma reactive compounds that are periodically deposited on the workpiece surface. Metal vapor and reactive elements are injected into the plasma, and their compounds are deposited on the workpiece surface. The device's electrodes and the workpiece surface are connected to a pulsed power supply circuit, with the current converted from combustion products. The workpiece surface is heated by the pulsed current and plasma. The surface layer and the deposited layer are heated together to above the phase transition temperature. A high temperature gradient is formed in localized areas of the workpiece surface. Rapid heating and cooling can create elastoplastic deformation waves on the surface layer, causing deformation of the surface material, significantly increasing heat transfer, and forming a nanocrystalline layer.

[0051] Specifically, such as Figure 1 As shown, Figure 1This is a schematic diagram of the metal component plasma detonation treatment device of the present invention; the explosion gun 5 is provided with a combustible gas inlet 6, an oxygen inlet 7, and an electric spark plug 8; the explosion is ignited by the discharge of the electric spark plug 8; the angle concentrator 9 on the explosion gun 5 is connected to the explosion gun annular chamber 22 through an auxiliary pipe 10; the explosion begins to develop in the upper annular chamber of the explosion gun annular chamber 22, and moves to the lower annular chamber of the explosion gun annular chamber 22 through the smooth connector 21 and connects to the annular distributor 20; a first annular insulator 23 and a second annular insulator 25 are also provided between the cathode electrode 14 and the anode electrode 13; an annular connector 24 is assembled between the first annular insulator 23 and the second annular insulator 25; the alloying element in powder or suspension form is introduced into the annular distributor 20 through the nozzle 11. The alloying element and the explosion combustion products are input into the annular chamber 19 of the reaction chamber through the annular distributor 20 and the angle reflector 12, and the annular chamber 19 of the reaction chamber is restricted by the axial surfaces of the anode electrode 13 and the cathode electrode 14. The front end of the annular chamber 19 of the reaction chamber is a conical chamber 15. The rod-shaped consuming electrode 2 is fixed along the axis of the central electrode 1 and cooled by a cooling gas flow introduced through the cooling gas inlet 3. The flow of the cooling gas flow is restricted by the inner wall 16 of the anode, which concentrates the gas flow to the electrode end 17. The gap between the anode electrode end 17 and the cathode outlet end 18 forms an electromagnetic lens that focuses the plasma during the passage of a pulsed current. The inner anode electrode 13 is fixed by the outer shell of the cathode electrode 14, the annular insulator 23, the annular connector 24 on the anode electrode 13, and the second annular insulator 25. The entire insulating structure is fastened with screws 4; the capacitive induction power supply is connected to the circuit through the first current lead 26 and the second current lead 27.

[0052] like Figure 2-4 As shown, Figure 2 This is a schematic diagram of the flow direction and energy conversion of explosion and combustion products in the metal component plasma detonation treatment device of the present invention; Figure 3 This is the invention Figure 2 AA section view; Figure 4 This is the invention Figure 2 A BB cross-sectional view; the conical portions of the anode and cathode form a conical chamber 15 of the reaction chamber; a consumable electrode 2 is mounted along the axis of the reaction chamber; a power supply circuit is connected via a first current lead 26 and a second current lead 27; the explosion gun 5, the explosion gun annular chamber 22, and the annular chamber 19 are filled with a combustible gas mixture. This mixture periodically initiates an explosive combustion mode at a frequency of 2–5 Hz. A conductive layer of explosive combustion products is formed in the annular chamber 19 and the conical chamber 15 of the reaction chamber. The low resistance (~20 Ω) of the explosion shock wave medium causes energy conversion in this layer to generate current, forming a magnetodynamic mode that accelerates and heats the explosive combustion products.

[0053] like Figure 5 As shown, Figure 5This is a schematic diagram of energy conversion between the consumable electrode and the workpiece surface in the plasma detonation treatment apparatus for metal parts of the present invention. Between the electrode end 17 and the cathode outlet end 18 at the plasma device outlet, a current switch generates a plasma jet 30. The plasma jet forms an impact compression layer 29 on the surface of the workpiece 28. Conductive plasma in this layer accumulates on the axis and flows towards the surface of the workpiece 28, which is connected to the cathode of the circuit. The plasma jet converts electrical energy between the consumable electrode-anode end 17 and the surface of the workpiece 28. The current changes polarity between the consumable electrode end 17, the annular end face of the cathode outlet end 18, and the surface of the workpiece 28, forming a reaction region, i.e., the plasma impact compression layer 29. In this region, a reaction of plasma compounds occurs, and these compounds flow and deposit on the cold surface of the workpiece. The circuit is closed, and a pulsed current passes through the surface of the metal workpiece, where the workpiece surface and the surface plasma compound are heated and rapidly cooled by a high gradient. The purpose of this apparatus is to form a high-speed jet of plasma compound, which is jetted onto the workpiece surface and forms a high-density impact compression layer 29. This region is maintained for 0.6–0.8 ms at currents exceeding 5000 A. Plasma compounds in this layer are deposited on the workpiece surface. During the formation of the impact compression layer, a discharge arc removes contaminants from the workpiece surface, which are then restored by a superheated hydrogen gas flow.

[0054] The device applies complex energy to the surface of the product through electric current, superheated combustion products, shock waves, sound waves, and electromagnetic waves.

[0055] As a result, a metallic alloyed nanocrystalline structure layer is formed on the workpiece surface, with the hardness of the middle part of the modified layer reaching 16 GPa. The hardness near the surface decreases to 11 GPa. Through repeated melting, molten pool alloying, and rapid cooling, the surface of the hardened layer has an amorphous layer with a thickness of ≤5 μm. The hardness gradually decreases from the hardened layer to the substrate, down to the substrate hardness of 4 GPa (the hardness of U10A steel in the delivery condition).

[0056] This device can use various consumable electrodes to introduce various heavy metals (W, Mo, CrNi) into the plasma. The hardening efficiency depends on the density of the introduced metal and the number of impact pulses. Introducing tungsten and / or molybdenum with 8 impact pulses yields the hardened layer with the highest hardness. Reducing the pulse number to 3 results in a hardened layer with a hardness of 12 GPa. Using a rod made of CrNi alloy as the consumable electrode yields the lowest hardness of the hardened layer.

[0057] At the device exit, energy is focused onto the workpiece surface into spots with a diameter of 10–20 mm. Within these spots, a high temperature gradient forms on the surface, resulting in corresponding elastoplastic deformation, thereby improving heat and mass transfer efficiency. Furthermore, the hardened surface generates strong acoustic vibrations, activating phonons and phonon-electron interactions within the metal workpiece material, while simultaneously increasing the metal's thermal conductivity and temperature gradient. The pulsed magnetic field activates magnons, which function similarly to phonons. Introducing metal vapor and reactive elements into each plasma pulse improves the plasma's electrical conductivity, the efficiency of plasma chemical synthesis of the modified layer, and the efficiency of workpiece surface alloying.

[0058] Die steel was hardened using a pulsed plasma apparatus. A tungsten electrode was used as the consumable electrode and fixed within the plasma apparatus. After plasma treatment, a modified layer with a thickness of 10 μm was obtained, containing 4% to 38% tungsten at a depth of 2 μm. The surface of the hardened tool contained only 45% iron, with the remainder being metallic and non-metallic alloying elements. A high-quality nanocrystalline layer was formed on the surface, exhibiting high anti-sticking properties, heat resistance, wear resistance, and corrosion resistance.

[0059] Alloying elements are introduced into the interelectrode gap of the plasma detonation treatment apparatus in the form of powder and gas. For example, nitrogen and silicon powder are introduced. Studies have shown that after treatment with a plasma detonation apparatus using nitrogen and silicon powder, a new nanocrystalline layer is formed on the surface of tool steel (matrix Fe, 5.0Cr, 1.0Si, 1.0V, 0.37C). This apparatus is used to modify the surface of stamping tools. Industrial tests on stamping tools show that plasma detonation treatment can improve their performance by 3 to 6 times.

[0060] During plasma detonation processing, the energy density of the workpiece surface depends not only on the energy stored in the capacitor accumulator but also on the discharge parameters of the RLC power supply circuit. The polarity of the workpiece surface relative to the central electrode of the plasma generator is an important technical parameter that affects the chemothermal process of the surface to be treated.

[0061] Based on the electric field strength in the gap between the electrodes of the plasma detonation device, the plasma parameters in the impact compression layer and the heat flux entering the workpiece surface were evaluated. The results show that when the workpiece is the anode, the energy density at the workpiece surface is the highest, and the electric field strength in the gap between the electrodes is 3.5 × 10⁻⁶. 5 At V / m, the energy density is 10 10 W / m 2 When the workpiece is the cathode, the heat flux will decrease.

[0062] As mentioned above, when the workpiece is the anode, the energy of the pulsed discharge can be utilized most efficiently, resulting in the maximum heat flux. On the other hand, when the workpiece surface is the cathode, the electric field strength mainly affects the deposition of metal vapor and plasma compounds in the plasma jet.

[0063] This processing method periodically introduces alloying elements and heats the workpiece surface with a high gradient, which is beneficial for achieving strong material deformation and abnormal mass transfer effects. At the same time, acoustic and magnetic vibrations enhance the processing effect.

[0064] The following processing mode is optimal: inductance L = 27 μH in the discharge circuit, capacitance C = 800 μF in the capacitor storage, voltage U = 3 kV on the capacitor plates, distance H = 40 mm to the surface, electrode indentation h = 18 mm, and overlap number K = 5 in the processing area. The hardened surface is achieved by periodically switching on or off the cathode or anode, depending on the conductivity of the plasma jet.

[0065] The deposition mode of the alloying element layer and the heating mode of the deposited layer and the hardened surface are optimized. Propane-butane can be used as the combustible gas. The introduction of alloying elements depends on process requirements; tungsten rods or molybdenum / titanium electrodes manufactured by powder metallurgy can be used, or sintered mechanical mixtures of various metal powders can be used. The temperature of the hardened surface is highest when the workpiece is anode-connected to the circuit. In this case, a high-gradient thermal vibration is formed in the surface layer, resulting in shear stress exceeding the material's ultimate strength. The intense plastic deformation of the surface material provides conditions for nanocrystal formation and dispersion alloying. Multiple sound waves with a sound pressure level range of 140–150 dB and a vibration frequency of 20–20000 Hz act simultaneously on the hardened layer, enhancing the processing. Acoustic action activates phonons in the material, while magnetic vibration activates magnons, thereby significantly improving the conductivity of the medium.

[0066] In plasma detonation treatment equipment, the initiation frequency of the combustible gas mixture (C3H8, O2, N2) can vary within the range of 1–5 Hz. Due to the explosive combustion mode of the combustible mixture within the detonation gun and its annular chamber, ionized combustion products are injected between the coaxial electrodes, and the RLC power circuit is closed. In the electrode gap of the plasma generator, current flows along the conductive gas volume behind the detonation wave front, and its ionization level increases over time. A magnetic field is generated around the central electrode, which interacts with the current flowing in the electrode gap, generating an electromagnetic force that accelerates the plasma. Furthermore, Joule heat is released as the current flows (due to the volume expansion of the heated gas), which enhances the gas dynamic component of the plasma. The plasma jet closes the circuit between the consumable electrode and the workpiece surface. When the consumable electrode is switched on to the anode, the thin layer of material at the electrode tip overheats and explodes (transitioning from a metastable state to a stable state), causing destruction. This ensures that heated and accelerated elements are synchronously injected from the electrodes into the plasma jet.

[0067] In the deceleration zone of the plasma jet, an impact compression layer of plasma and electrode erosion products forms on the treated surface. This layer interacts with the workpiece surface for a duration of 0.4–0.6 ms, with a heat flux of 0.3 × 10⁻⁶. 5 ~1.4×106 W / cm 2 The heat flux varies within a certain range. The parameters of the power supply circuit RLC, the distance H, and the electrode indentation h are adjusted. Electrode indentation primarily affects the diameter of the contact spot between the plasma and the workpiece surface, ensuring it varies within the range of 10mm to 20mm. Therefore, the heat flux density can be controlled under the same pulse energy.

[0068] The developed device also features the ability to introduce one or more elements from Groups III, IV, V, and VI of the periodic table, or compounds thereof, into the plasma. When the surface is connected to the cathode, these elements are deposited on the surface. The elastoplastic deformation of the surface layer, combined with the electromagnetic effect generated by a pulsed current (≤6kA) acting on the workpiece surface, enhances the mass transfer and dispersion mechanisms of the grains.

[0069] The plasma detonation treatment apparatus for metal parts features multiple annular detonation guns that generate high-energy jets of combustion products and alloying elements. Within the apparatus, electrical energy distributed across the workpiece surface is converted within the reaction chamber. This reduces the energy density per unit area of ​​the electrodes, thereby minimizing electrode surface ablation. Ultimately, the large-area electrical energy conversion distribution significantly reduces contamination of the plasma jet by electrode ablation products and dramatically improves the efficiency of the plasma detonation treatment apparatus (by 10–20 times).

[0070] The introduction of alloying elements and the conversion of electrical energy occur in multiple localized regions within the reaction chamber, which significantly reduces the specific energy density and ensures uniform distribution of alloying elements within the plasma jet. The sum of the current energy from all localized regions and products of the explosive combustion ensures the thermal activation of the alloying elements and generates a high-speed plasma jet—combining superheated combustion products and alloying elements. The plasma jet flows toward the treated surface and forms an impact compression layer. Within this layer, the workpiece surface is rapidly heated and cooled, and the plasma elements alloy the surface.

[0071] Experimental work shows that within 3–5 ms between pulses, the plasma chemical synthesis products flow from the interelectrode gap to the workpiece surface and deposit. Subsequent plasma pulses melt the thin surface layer, mix it with the workpiece surface layer, and saturate it with alloying elements.

[0072] Based on theoretical analysis using nonstationary heat conduction equations, the heat flux in iron-based alloys was evaluated. The results show that the heat flux is highest at a duration of τ = 0.6 ms and a power of q = 7.2 × 10⁻⁶ ms. 8 W / m 2 The temperature varies at different distances from the workpiece surface due to the duration of a single pulse. Numerical analysis shows that the heating and cooling rates can reach 10. 7 K / s, the temperature gradient across the modified layer thickness can reach 2.5×10 K / s. 7K / m. The surface layer heated to its melting temperature has time to cool between multiple pulses at a frequency of 2 Hz. Multiple pulsed plasma treatments on the surface can induce periodic deformation, phase hardening, and structural refinement of the surface layer.

[0073] The effectiveness of this invention can be tested by hardening the surface of the stamping tool. Nitrogen gas and amorphous silicon fine powder jets are supplied into the inter-electrode gap of the device to introduce additional alloying elements silicon and nitrogen.

[0074] Chromium silicide treatment is a high-temperature (950–1200℃) chemical heat treatment process. Parts treated with chromium silicide exhibit higher oxidation resistance and acid resistance, as well as high-temperature corrosion resistance at 800–1000℃. The distribution of alloying elements in the thickness of the modified layer was determined using glow discharge spectroscopy.

[0075] After pulsed plasma treatment of the mold steel surface with elements such as tungsten, silicon, and nitrogen, precise quantitative and layer-by-layer analysis was performed. The results showed that the distribution depth of the alloying elements reached 10 μm. A new material with high alloying element content was formed on the surface of the mold steel. This material possesses a nanocrystalline structure.

[0076] Experimental work was conducted on 4X5MF1S die steel. This steel is used to manufacture tools that operate under long-term thermal cycling conditions at 630°C (such as extrusion rods, needles for pipe piercing, hammer-forged inserts and stamping inserts, tools for upsetting workpieces, etc.). To improve the heat resistance of the tool's working layer, it is necessary to increase the content of tungsten, silicon, nitrogen, and carbon in the surface layer, as well as refine the grain structure and perform alloy dispersion strengthening to the nanoscale.

[0077] The optimal process parameters for pulsed plasma treatment are: inductance of the discharge circuit L = 27 μH, capacitance of the capacitor storage C = 800 μF, voltage on the capacitor bank plates U = 3 kV, distance to the surface H = 40 mm, electrode indentation h = 18 mm, overlap of the treatment area K = 5, and the consumable electrode is a tungsten electrode.

[0078] Pulsed plasma hardening of die steel using consumable tungsten electrodes yielded a 10 μm thick layer containing 4% to 38% tungsten at a depth of 2 μm. The hardened tool surface contained only 45% iron, with the remainder being metallic and non-metallic alloying elements. A high-quality nanocrystalline layer was formed on the surface, exhibiting high anti-sticking properties, heat resistance, high wear resistance, and corrosion resistance. Industrial trials of stamping tools showed that pulsed plasma hardening can improve their performance by 3 to 6 times.

[0079] A composite alloying treatment of tungsten and carbon was performed on the surface of a 40Kh steel workpiece in air. High-energy-density plasma heating of the surface ensured a high temperature gradient during heating and cooling, achieving an anomalous alloying, deformation, and refinement mechanism of the surface structure. The study showed that a modified layer was obtained on the surface. This layer has a clear boundary with the base metal. The surface roughness remained unchanged. Examination of the sample using a transmission electron microscope equipped with an energy dispersive chromatograph analysis system confirmed that the modified layer on the surface has a high content of tungsten (38 at.%) and oxygen (13.8 at.%). No oxygen was found near the surface, with a tungsten content of 19.38 at.%, gradually decreasing to 4 at.% from the surface to a depth of 1 μm. The crystal structure of the modified layer is close to a nanocrystalline structure. The surface microhardness is 1073 HV. 1000 Because the modified layer is very thin, it will bend under a 1000g load, making this method of hardness assessment inaccurate; the measured hardness is lower than the actual hardness. At a depth of 50μm, the alloy structure does not show significant changes, but the hardness is 451HV. 300 The surface hardness is approximately three times that of the matrix. Analysis of the sample using energy dispersive spectroscopy and scanning electron microscopy revealed that the surface layer contained 7 at% carbon. Tungsten was introduced into the plasma as an erosion product of the metal rod electrode, while nitrogen and carbon were introduced into the plasma as components of the explosive mixture.

[0080] Plasma detonation equipment can simultaneously endow workpiece surfaces with high heat resistance, high hardness, and high strength. The abrasive wear performance of workpieces hardened by plasma detonation was tested through reciprocating wear tests. The grinding media consisted of 5mm diameter cylindrical pins made of SiC with a hardness of 30 GPa. Comparison of hardened and unhardened samples showed that the surface wear resistance increased by hundreds of times after pulsed plasma treatment. Studies indicated that the friction coefficient of the modified workpiece surface was more stable, remaining constant within the range of 0.3, without fluctuations over time. The friction coefficient of the untreated surface fluctuated between 0.4 and 0.8. Analysis of the test results showed that the hardened workpiece did not exhibit failure modes such as brittle fracture. The plasma detonation treatment increased the content of refractory alloying elements in the surface layer of the workpiece. Experimental results indicate that the surface modification treatment of the workpiece by this device has a combined effect—accelerating the mass transfer of plasma components into the hardened surface. After treatment, the surface layer contained alloying elements (W, Si, N, C) at a depth of 5–10 μm. At a depth of 40 μm, the tool undergoes alloying, recrystallization, and the formation of nanocrystals.

[0081] The plasma detonation treatment device for this metal component can achieve surface alloying of the workpiece and sample. This is because the activation of phonons and magnons enhances the heat transfer process, creating a high-temperature gradient and strong elastoplastic deformation of the material on the surface. Ultimately, a new layer of nanocrystals is formed on the workpiece surface.

[0082] Furthermore, unlike the prototype device, this device operates with lower consumption of alloying elements and electrical energy, which ensures the formation of a more uniform modified layer and also results in higher performance and efficiency.

[0083] 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.

[0084] Although this document frequently uses reference numerals from the figures, such as: center electrode 1, consumable electrode 2, cooling gas inlet 3, screw 4, explosive gun 5, combustible gas inlet 6, oxygen inlet 7, spark plug 8, angle concentrator 9, auxiliary pipe 10, nozzle 11, corner reflector 12, anode electrode 13, cathode electrode 14, conical chamber 15, pipe wall 16, electrode end 17, cathode outlet end 18, annular chamber 19, annular distributor 20, smooth connector 21, explosive gun annular chamber 22, first annular insulator 23, annular connector 24, second annular insulator 25, first current lead 26, second current lead 27, workpiece 28, impact compression layer 29, plasma jet 30, 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 essence of the invention; interpreting them as any additional limitation would be contrary to the spirit of the invention.

Claims

1. A plasma detonation treatment apparatus for metal components, characterized in that: include: A capacitive sensing power supply is provided, wherein the capacitive sensing power supply is connected to the cathode electrode (14) and the center electrode (1) respectively through a first current lead (26) and a second current lead (27), and the center electrode is fixedly connected to the anode electrode (13). The reaction chamber includes an annular chamber (19) and a conical chamber (15) surrounding the anode electrode (13), and is formed by the cavity between the anode electrode (13) and the cathode electrode (14), separating the cathode electrode (14) from the anode electrode (13); the explosive gun (5) is connected to the explosive gun annular chamber (22) and is used to introduce combustible gas and perform periodic detonation; Nozzle (11), which is connected to an annular chamber (19), for introducing one or more elements of Groups III, IV, V, and VI of the periodic table and their compounds into the annular chamber (19); Consumable electrode (2), which is fixed on the axis of the center electrode (1) and the anode electrode (13) and passes through the anode electrode (13), is used to provide alloying elements; a cooling cavity is provided between the consumable electrode (2) and the anode electrode (13), and the cooling cavity separates the consumable electrode (2) from the anode electrode (13); The nozzle (11) is tangentially connected to the annular distributor (20) in the lower annular chamber of the explosive gun. 10 to 15 holes are evenly distributed on the circumference of the annular distributor (20). A corner reflector (12) installed on each hole is connected to the annular chamber (19) to uniformly supply the explosion combustion products to the annular chamber (19) and uniformly introduce one or more elements of Groups III, IV, V and VI of the periodic table and their compounds into the reaction chamber.

2. The plasma detonation treatment apparatus for metal components according to claim 1, characterized in that: The explosive gun (5) is equipped with a combustible gas inlet (6), an oxygen inlet (7), and an electric spark plug (8); the electric spark plug (8) is connected to the auxiliary pipe (10) through an angle concentrator (9) and periodically discharges to ignite the combustible gas mixture.

3. The plasma detonation treatment apparatus for metal components according to claim 1 or 2, characterized in that: The angle concentrator (9) on the explosive gun (5) is connected to the explosive gun annular chamber (22) via an auxiliary pipe (10).

4. The plasma detonation treatment apparatus for metal components according to claim 3, characterized in that: The explosive gun annular chamber (22) is divided into two identical annular chambers, which are connected by a smooth connector (21). The auxiliary pipe (10) is tangentially input to the end of the upper annular chamber and the front end of the lower annular chamber of the explosive gun.

5. The plasma detonation treatment apparatus for metal components according to claim 1, characterized in that: The total cross-sectional area of ​​the corner reflector (12) is smaller than the total cross-sectional area of ​​the explosive gun ring chamber.

6. The plasma detonation treatment apparatus for metal components according to claim 1, characterized in that: The explosive gun's annular chamber (22), annular cavity (19), anode electrode (13), and center electrode (1) are coaxially arranged.

7. The plasma detonation treatment apparatus for metal components according to claim 1, characterized in that: A first annular insulator (23) and a second annular insulator (25) are provided between the cathode electrode (14) and the anode electrode (13); an annular connector (24) is assembled between the first annular insulator (23) and the second annular insulator (25).

8. The plasma detonation treatment apparatus for metal components according to claim 1, characterized in that: The cooling chamber consists of a cavity between the consuming electrode (2) and the inner wall of the anode (16). The cooling gas flow entering the cooling chamber through the cooling gas inlet (3) is concentrated along the inner wall of the anode (16) to the end of the electrode (17) for cooling the consuming electrode (2).

9. The plasma detonation treatment apparatus for metal components according to claim 8, characterized in that: A cathode outlet end (18) is formed at the bottom of the cathode electrode (14), and a plasma jet (30) for impacting the surface of the workpiece (28) is formed between the cathode outlet end (18) and the electrode end (17).

10. The plasma detonation treatment apparatus for metal components according to claim 1 or 8, characterized in that: When the electrode end (17) of the consumed electrode (2) is consumed, it can be compensated by axial movement, which is cooled by airflow.

11. The plasma detonation treatment apparatus for metal components according to claim 1, characterized in that: The alloying elements are placed on the inner surface of the reaction chamber in the form of a regenerable coating, which can be re-prepared by thermal spraying after consumption.

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