A fine and deep hole plasma nitriding equipment and method based on plasma nitriding anode bar

Abstract

The present application relates to the technical field of plasma nitriding surface treatment, and particularly relates to a fine and deep hole plasma nitriding equipment and method based on a plasma nitriding anode rod, wherein the high-toughness auxiliary anode is made of molybdenum alloy material with two or three alloy elements of C, Ti and Cr added in the molybdenum base, so that the high-toughness auxiliary anode can further improve the performance of the nitriding layer during the plasma nitriding process. The present application solves the problems of active nitrogen ion kinetic energy attenuation and hollow effect during the plasma nitriding of the inner wall of the fine and deep hole, successfully realizes the glow discharge in the deep center part of the inner wall of the fine and deep hole, and applies the plasma nitriding technology to the surface strengthening of the inner wall of the fine and deep hole. Meanwhile, due to the sputtering effect of the high-toughness auxiliary anode, the plasma nitriding effect of the workpiece surface is enhanced, the surface hardness and high-temperature resistance of the inner wall of the workpiece are further improved, and the high-precision, high-efficiency and uniform plasma nitriding strengthening treatment of the inner wall of the fine and deep hole is realized.

Description

Technical Field

[0001] This invention relates to the field of plasma nitriding surface treatment technology, and in particular to a fine-deep-hole plasma nitriding device and method based on plasma nitriding anode rods. Background Technology

[0002] When the inner walls of fine and deep holes are used in complex and harsh environments such as high temperature, high pressure, strong friction and corrosion, they often need to rely on one or more surface functional coating technologies to give the surface special functional protection, thereby ensuring the safety and reliability of the components during service.

[0003] Plasma nitriding, a commonly used surface treatment technology, typically uses the workpiece as the cathode and the furnace as the anode. In a vacuum (hundreds of Pa) environment, a glow discharge phenomenon is generated under the action of a high-voltage DC electric field in a nitrogen-hydrogen atmosphere. Active nitrogen atoms bombard the workpiece surface at high speed, and through adsorption and diffusion, nitrogen penetrates into the workpiece surface to form a nitrided layer, which significantly improves the surface hardness, wear resistance, and corrosion resistance of the material.

[0004] However, when plasma nitriding technology is applied to strengthen the inner wall of fine deep holes, the combined effects of kinetic energy attenuation and hollow effect make it difficult for glow discharge to occur on the inner wall. The generated ionized active nitrogen ions are often difficult to sputter to the deep center of the inner wall of the fine deep tube, which ultimately leads to uneven nitriding or even failure to complete nitriding on the inner wall of the fine deep hole. Summary of the Invention

[0005] The purpose of this invention is to provide a plasma nitriding device and method for fine deep holes based on plasma nitriding anode rods. This aims to solve the technical problem in the prior art where, when plasma nitriding technology is applied to strengthen the inner wall of fine deep holes, the combined effects of kinetic energy attenuation and hollow effects make glow discharge on the inner wall difficult. Consequently, the generated ionized active nitrogen ions are often difficult to sputter to the deep center of the inner wall of the fine deep hole, ultimately resulting in uneven nitriding or even failure to complete nitriding.

[0006] To achieve the above objectives, the present invention employs a fine-depth-hole plasma nitriding equipment based on plasma nitriding anode rods, comprising a furnace body, a fine-depth tube, tooling, a cathode plate, a gas supply device, a vacuum system, and a power supply. The gas supply device and the vacuum system are both mounted on the furnace body, the cathode plate is also mounted on the furnace body, the fine-depth tube is mounted on the cathode plate, the tooling is mounted on the fine-depth tube, and the negative terminal of the power supply is connected to the cathode plate.

[0007] The tooling consists of two pieces, both of which are mounted on the thin, deep tube and located at both ends of the tube.

[0008] This invention also provides a fine-deep-hole plasma nitriding method based on plasma nitriding anode rods, employing the fine-deep-hole plasma nitriding equipment based on plasma nitriding anode rods as described above, characterized by comprising the following steps:

[0009] Step 1: Use mechanical pulverization to prepare the bulk materials of pure molybdenum, pure chromium, titanium hydride, and graphite into micron-sized powder particles to obtain raw material powder for later use.

[0010] Step 2: Mix the prepared molybdenum powder, chromium powder, titanium hydride powder and graphite in a certain proportion to obtain a mixture for later use;

[0011] Step 3: Press the mixture into blanks of the desired shape using a molding machine under a pressure of 150-500MPa;

[0012] Step 4: Heat the pressed billet to 1500-2300℃ under a protective atmosphere and sinter it under pressure for 1-8 hours. After cooling, the molybdenum alloy sintered billet is obtained.

[0013] Step 5: The molybdenum alloy sintered billet is thermoplastically processed at 500-1500℃ to obtain the required plasma nitriding anode rod.

[0014] Step 6: Anneal the thermoplastic plasma nitriding anode rod at 1000-1300℃ to obtain a high-strength and tough auxiliary anode;

[0015] Step 7: Install the high-strength and tough auxiliary anode onto the thin deep tube using the tooling, lock and position it, and connect one end of the high-strength and tough auxiliary anode to the positive terminal of the power supply;

[0016] Step 8: Using the vacuum system and the gas supply device in combination, maintain the furnace body in a vacuum state containing nitrogen and hydrogen.

[0017] Step 9: Finally, operate the power supply to perform plasma nitriding strengthening treatment on the inner wall of the fine deep tube, thus completing the fine deep hole plasma nitriding based on the plasma nitriding anode rod.

[0018] In step one, the selected pure molybdenum, pure chromium, titanium hydride, and graphite have a purity of not less than 99%, and the average particle size of the powder is 30-50 μm.

[0019] In step two, a ball mill or mixer is used for mixing.

[0020] In step four, the sintering protective atmosphere includes a vacuum environment or a mixture of one or more of nitrogen, argon, and hydrogen.

[0021] In step five, thermoplastic forming can be achieved by one or more combinations of forging, rotary forging, and extrusion.

[0022] When installing the high-strength and tough auxiliary anode on the thin tube, ensure that the thin tube and the high-strength and tough auxiliary anode are concentric.

[0023] This invention discloses a fine-hole plasma nitriding device and method based on plasma nitriding anode rods. The preparation method of this invention is simple and the raw materials are clear. First, a high-strength and tough auxiliary anode is prepared. By using a molybdenum alloy material with two or three alloying elements, C, Ti, and Cr, in a molybdenum base, the high-strength and tough auxiliary anode can further improve the nitriding performance during the plasma nitriding process. Among them, C element can improve the corrosion resistance and surface hardness of the workpiece; Ti element can improve the surface hardness and high-temperature resistance of the workpiece; and Cr element can improve the wear resistance of the inner wall of the workpiece. At the same time, the high-strength and tough auxiliary anode has good electrical and thermal conductivity and does not deform under long-term high-temperature conditions. Then, the high-strength and tough auxiliary anode is placed in the fine-hole plasma nitriding device based on the plasma nitriding anode rods for nitriding.

[0024] This invention solves the problems of active nitrogen ion kinetic energy attenuation and hollow effect during plasma nitriding of the inner wall of fine deep holes, and successfully achieves glow discharge in the deep center of the inner wall of fine deep holes, applying plasma nitriding technology to the surface strengthening of the inner wall of fine deep holes; at the same time, due to the sputtering effect of the high-strength and tough auxiliary anode, the plasma nitriding effect on the workpiece surface is enhanced, further improving the surface hardness and high temperature resistance of the inner wall of the workpiece, and realizing high-precision, high-efficiency and uniform plasma nitriding strengthening treatment of the inner wall of fine deep holes. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 This is a schematic diagram of the structure of the fine-deep-hole plasma nitriding device based on plasma nitriding anode rods of the present invention.

[0027] Figure 2 This is a metallographic image of the nitrided layer after plasma nitriding using a high-strength and tough auxiliary anolyte, as per the present invention.

[0028] 1-Furnace body, 2-Slim tube, 3-Tooling, 4-Cathode plate, 5-Gas supply device, 6-Vacuum system, 7-Power supply, 8-High-strength and tough auxiliary anode. Detailed Implementation

[0029] The embodiments of the present invention are described in detail below. Examples of the embodiments are shown in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, but should not be construed as limiting the present invention.

[0030] Please see Figure 1 and Figure 2 ,in Figure 1 This is a schematic diagram of the structure of the fine-deep-hole plasma nitriding device based on plasma nitriding anode rods according to the present invention. Figure 2 This is a metallographic image of the nitrided layer after plasma nitriding using a high-strength and tough auxiliary anolyte, as per the present invention.

[0031] This invention provides a fine-hole plasma nitriding device based on plasma nitriding anode rods, comprising a furnace body 1, a fine-hole tube 2, a tooling 3, a cathode plate 4, a gas supply device 5, a vacuum system 6, and a power supply 7. The gas supply device 5 and the vacuum system 6 are both mounted on the furnace body 1, the cathode plate 4 is also mounted on the furnace body 1, the fine-hole tube 2 is mounted on the cathode plate 4, the tooling 3 is mounted on the fine-hole tube 2, and the negative terminal of the power supply 7 is connected to the cathode plate 4.

[0032] The number of tooling 3 is two, and both tooling 3 are installed on the thin deep tube 2 and located at both ends of the thin deep tube 2.

[0033] In this embodiment, the furnace body 1, the fine-depth tube 2, the tooling 3, the cathode plate 4, the gas supply device 5, the vacuum system 6, and the power supply 7 work together to achieve plasma nitriding strengthening treatment of the inner wall of the fine-depth hole of the high-strength and tough auxiliary anode 8.

[0034] This invention also provides a fine-deep-hole plasma nitriding method based on plasma nitriding anode rods, employing the fine-deep-hole plasma nitriding equipment based on plasma nitriding anode rods as described above, characterized by comprising the following steps:

[0035] Step 1: Using mechanical pulverization, the blocky materials of 99.5% pure molybdenum, pure chromium, titanium hydride and graphite are prepared into powder particles with an average particle size of 45 μm, and the raw material powder is used for later use.

[0036] Step 2: Weigh 2 wt% chromium powder, 2 wt% titanium hydride powder, 1.3 wt% graphite and the balance being pure molybdenum according to the proportions, mix them using a ball mill, and set the mixture aside.

[0037] Step 3: Press the mixture into blanks of the desired shape using a molding machine under a pressure of 400 MPa;

[0038] Step 4: The pressed billet is heated to 2100℃ under nitrogen protection and sintered under pressure for 2 hours. After cooling, the molybdenum alloy sintered billet is obtained.

[0039] Step 5: The molybdenum alloy sintered billet is thermoplastically processed at 1300℃ to obtain the required plasma nitriding anode rod.

[0040] Step 6: Anneal the thermoplastic plasma nitriding anode rod at 1000℃ to obtain high-strength and tough auxiliary anode 8;

[0041] Step 7: Install the high-strength and tough auxiliary anode 8 onto the thin deep tube 2 using the tooling 3, and lock it in place. Connect one end of the high-strength and tough auxiliary anode 8 to the positive terminal of the power supply 7.

[0042] Step 8: Using the vacuum system 6 and the gas supply device 5 in combination, the furnace body 1 is kept in a vacuum state (hundreds of Pa) containing nitrogen and hydrogen.

[0043] Step 9: Finally, operate the power supply 7 to perform plasma nitriding strengthening treatment on the inner wall of the fine deep tube 2, thus completing the fine deep hole plasma nitriding based on the plasma nitriding anode rod.

[0044] The preparation method of this invention is simple and the raw materials are clear. First, a high-strength and tough auxiliary anode 8 is prepared. By using a molybdenum alloy material with two or three alloying elements, C, Ti, and Cr, in a molybdenum base, the high-strength and tough auxiliary anode 8 can further improve the diffusion performance during plasma nitriding. Among them, C element can improve the corrosion resistance and surface hardness of the workpiece; Ti element can improve the surface hardness and high temperature resistance of the workpiece; Cr element can improve the wear resistance of the inner wall of the workpiece. At the same time, the high-strength and tough auxiliary anode 8 has good electrical and thermal conductivity and does not deform under long-term high temperature conditions. Then, the high-strength and tough auxiliary anode 8 is placed in a fine deep-hole plasma nitriding equipment based on the plasma nitriding anode rod for nitriding.

[0045] This invention solves the problems of active nitrogen ion kinetic energy attenuation and hollow effect during plasma nitriding of the inner wall of fine deep holes, and successfully achieves glow discharge in the deep center of the inner wall of fine deep holes, applying plasma nitriding technology to the surface strengthening of the inner wall of fine deep holes; at the same time, due to the sputtering effect of the high-strength and tough auxiliary anode 8, the plasma nitriding effect on the workpiece surface is enhanced, further improving the surface hardness and high temperature resistance of the inner wall of the workpiece, and realizing high-precision, high-efficiency and uniform plasma nitriding strengthening treatment of the inner wall of fine deep holes.

[0046] After plasma nitriding using this invention, the nitriding layer depth is approximately 200 μm and the surface hardness of the nitrided layer is 800 HV.

[0047] The above description discloses only one preferred embodiment of the present invention, and should not be construed as limiting the scope of the present invention. Those skilled in the art will understand that all or part of the processes of the above embodiments can be implemented, and equivalent changes made in accordance with the claims of the present invention are still within the scope of the invention.

Claims

1. A method for fine-deep-hole plasma nitriding based on plasma nitriding anode rods, characterized in that, Includes the following steps: Step 1: Use mechanical pulverization to prepare the bulk materials of pure molybdenum, pure chromium, titanium hydride, and graphite into micron-sized powder particles to obtain raw material powder for later use. Step 2: Mix the prepared molybdenum powder, chromium powder, titanium hydride powder and graphite in a certain proportion to obtain a mixture for later use; Step 3: Press the mixture into blanks of the desired shape using a molding machine under a pressure of 150-500MPa; Step 4: Heat the pressed billet to 1500-2300℃ under a protective atmosphere and sinter it under pressure for 1-8 hours. After cooling, the molybdenum alloy sintered billet is obtained. Step 5: The molybdenum alloy sintered billet is thermoplastically processed at 500-1500℃ to obtain the required plasma nitriding anode rod. Step 6: Anneal the thermoplastic plasma nitriding anode rod at 1000-1300℃ to obtain a high-strength and tough auxiliary anode; Step 7: Install the high-strength and tough auxiliary anode onto the thin tube using a tooling and lock it in place. Connect one end of the high-strength and tough auxiliary anode to the positive terminal of the power supply. Step 8: Use the vacuum system and gas supply device in combination to maintain a nitrogen-hydrogen atmosphere inside the furnace. Step 9: Finally, operate the power supply to perform plasma nitriding strengthening treatment on the inner wall of the fine deep tube, thus completing the fine deep hole plasma nitriding based on the plasma nitriding anode rod. The equipment used for fine-deep-hole plasma nitriding based on plasma nitriding anode rods includes a furnace body, a fine-deep tube, tooling, a cathode plate, a gas supply device, a vacuum system, and a power supply. The gas supply device and the vacuum system are both installed on the furnace body, the cathode plate is also installed on the furnace body, the fine-deep tube is installed on the cathode plate, the tooling is installed on the fine-deep tube, and the negative terminal of the power supply is connected to the cathode plate. The number of tooling fixtures is two, and both tooling fixtures are installed on the thin deep tube and located at both ends of the thin deep tube; In step one, the selected pure molybdenum, pure chromium, titanium hydride, and graphite have a purity of not less than 99%, and the average particle size of the powder is 30-50 μm.

2. The fine-deep-hole plasma nitriding method based on plasma nitriding anode rod as described in claim 1, characterized in that, In step two, a ball mill or mixer is used for mixing.

3. The fine-deep-hole plasma nitriding method based on plasma nitriding anode rods as described in claim 2, characterized in that, In step four, the sintering protective atmosphere includes a vacuum environment or a mixture of one or more of nitrogen, argon, and hydrogen.

4. The fine-deep-hole plasma nitriding method based on plasma nitriding anode rods as described in claim 3, characterized in that, In step five, thermoplastic forming is performed using one or more combinations of forging and extrusion.

5. The fine-deep-hole plasma nitriding method based on plasma nitriding anode rods as described in claim 4, characterized in that, When installing the high-strength and tough auxiliary anode on the thin tube, ensure that the thin tube and the high-strength and tough auxiliary anode are concentric.

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