Low-temperature ion nitriding method and application

Abstract

The invention discloses a low-temperature ion nitriding method and application. The low-temperature ion nitriding method comprises the following steps: under a selected temperature condition, carrying out ion etching treatment on the surface of a workpiece by adopting an arc-enhanced glow discharge process, and then carrying out plasma nitriding treatment on the workpiece by adopting an arc-enhanced plasma process to obtain a nitrided workpiece; wherein positive and negative alternating voltage is applied to the workpiece in the arc enhanced plasma process. According to the low-temperature ion nitriding method, nitriding can be achieved at the low temperature, the deformation degree of the workpiece is effectively improved, and the low-temperature ion nitriding method is widely suitable for surface strengthening of tools, molds, metal parts and the like.

Description

Technical Field

[0001] The invention belongs to the field of material surface processing, and in particular relates to a low-temperature ion nitriding method and application. Background Art

[0002] Nitriding is an important chemical heat treatment technology that can significantly improve the surface hardness and wear resistance of metal materials. Nitriding methods are usually divided into gas nitriding, liquid nitriding, solid nitriding and ion nitriding, among which ion nitriding has been widely used due to its advantages of high efficiency, low pollution, easy control and small deformation of workpieces.

[0003] At present, ion nitriding technology has been widely used for surface hardening of gears, traditional shafts, molds and other products. However, the temperature of traditional ion nitriding is usually high (450-590°C), and the gas pressure required in the vacuum chamber is as high as 100-500Pa. Higher temperatures will cause the workpiece to deform easily and the precision will be difficult to control; the high pressure in the furnace is to obtain a higher ion concentration to ensure the nitriding efficiency. In addition, the nitriding efficiency of traditional nitriding technology is extremely low when the temperature is too low, and it is difficult to obtain a high-hardness nitriding layer structure, especially for titanium alloy substrates, which are almost impossible to achieve nitriding. Therefore, how to achieve ion nitriding under low temperature conditions is the key to promoting the development of nitriding technology. Summary of the invention

[0004] The main purpose of the present invention is to provide a low temperature ion nitriding method and application to overcome the deficiencies in the prior art.

[0005] In order to achieve the above-mentioned invention object, the technical solution adopted by the present invention includes:

[0006] One aspect of the present invention provides a method for low-temperature ion nitriding, which comprises: under selected temperature conditions, using an arc-enhanced glow discharge process to perform ion etching on the surface of a workpiece, and then using an arc-enhanced plasma process to perform plasma nitriding on the workpiece to obtain a nitrided workpiece; wherein, in the arc-enhanced plasma process, positive and negative alternating voltages are applied to the workpiece.

[0007] Another aspect of the present invention provides a nitrided workpiece prepared by the above-mentioned low-temperature ion nitriding method, wherein the surface hardness is 1200 HV 0.2 above.

[0008] Compared with the prior art, the present invention has at least the following advantages:

[0009] The method provided by the present invention utilizes low temperature to control the deformation degree of the product surface, utilizes arc enhanced plasma technology to promote gas ionization, obtains a high nitrogen ion concentration, applies bipolar pulse bias to the workpiece, wherein the positive electric field attracts thermal electrons, locally preheats the workpiece surface by pulsed Joule heating, and the sputtering effect of the high-voltage negative electric field introduces high-density defects on the workpiece surface, thereby increasing the diffusion rate of active nitrogen atoms. Based on the coordinated cooperation of multiple technologies and nitriding process parameters, in addition to further improving the nitriding efficiency, a more ideal nitriding layer structure can be obtained, the deformation degree of the product can be controlled, and the mechanical properties can also be enhanced, thereby ensuring the service performance of the product. The method provided by the present invention requires a relatively low process temperature, has great application prospects in products with extremely high deformation requirements, and reduces the energy consumption caused by macroscopic overall heating. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0011] Figure 1 A schematic diagram of the structure of a low-temperature ion nitriding device in a typical embodiment of the present invention;

[0012] Figure 2 It is a schematic diagram of the positive and negative alternating voltage waveform output by a bipolar pulse power supply in a typical embodiment of the present invention;

[0013] Figure 3 is a metallographic micrograph of the M2 high-speed steel sheet in Example 1 of the present invention;

[0014] Figure 4 is a metallographic micrograph of the M2 high-speed steel sheet in Example 2 of the present invention;

[0015] Figure 5 is a metallographic micrograph of the M2 high-speed steel sheet in Example 3 of the present invention;

[0016] Figure 6 is a metallographic micrograph of the M2 high-speed steel sheet in Example 4 of the present invention;

[0017] Figure 7 It is a metallographic micrograph of the M2 high-speed steel sheet in Comparative Example 1 of the present invention.

[0018] Figure numerals: 1 - vacuum chamber, 2 - workpiece holder, 3 - heating tube, 4 - arc target, 5 - baffle, 6 - auxiliary anode, 7 - bipolar pulse power supply. DETAILED DESCRIPTION

[0019] The present invention will be more fully understood by reading the following specific embodiments. However, it should be understood that the specific embodiments disclosed below are only exemplary of the present invention, and the present invention can be embodied in various forms. Therefore, the specific functional details disclosed herein should not be interpreted as limiting, but only as the basis for the claims and as a representative basis for teaching those skilled in the art to adopt the present invention in different ways in any appropriate detailed embodiment.

[0020] As one aspect of the technical solution of the present invention, a method of low-temperature ion nitriding is involved, comprising: under selected temperature conditions, an arc-enhanced glow discharge process is used to perform ion etching on the surface of a workpiece, and then an arc-enhanced plasma process is used to perform plasma nitriding on the workpiece to obtain a nitrided workpiece; wherein, in the arc-enhanced plasma process, positive and negative alternating voltages are applied to the workpiece.

[0021] In some embodiments, the low temperature ion nitriding method includes: placing the workpiece in a reaction chamber, evacuating the reaction chamber to a background vacuum, heating the reaction chamber to a selected temperature, and then performing the ion etching process.

[0022] In the present invention, the ion etching treatment can be argon ion etching, but is not limited to argon ions. Inert gas ions (argon, krypton, etc.) or mixed reducing gas ions (hydrogen) etching can be used. This step is mainly used to clean the surface of the workpiece and treat the pollutants and oxide layer on the surface of the workpiece so that the subsequent nitrogen ions can penetrate smoothly. Considering the industrial cost-effectiveness, argon ions or argon ions plus hydrogen ions are most suitable.

[0023] In the present invention, the argon ion etching refers to arc enhanced glow discharge technology, which generates high-density electrons through arc discharge. The electrons are attracted by the auxiliary anode, leave the target surface area, collide with the introduced gas, and ionize gas ions. The negative voltage on the workpiece attracts the gas ions and bombards its surface. The arc target can be a metal target such as Ti, Cr or an alloy target such as TiAl.

[0024] In some preferred embodiments, the selected temperature is 100°C-400°C.

[0025] In some preferred embodiments, the gas pressure of the reaction chamber is 1-10 Pa.

[0026] In some preferred embodiments, the heating method includes heating with infrared electric heating tubes.

[0027] In some embodiments, the ion etching treatment time is 10-60 minutes.

[0028] In some embodiments, the arc enhanced glow discharge process includes: connecting an auxiliary anode to the positive pole of a DC power supply, connecting a workpiece to the output end of a pulse power supply, outputting a negative voltage, striking an arc with an arc target, and introducing argon gas.

[0029] In some preferred embodiments, in the arc enhanced glow discharge process, a bipolar pulse power supply is used, the negative voltage is 200-1200V, the pulse frequency is 80-10kHz, and the duty cycle is 0.2-1.0.

[0030] In some preferred embodiments, in the arc enhanced glow discharge process, the flow rate of the argon gas is 100-200 sccm.

[0031] In some embodiments, the arc enhanced plasma process includes: connecting the auxiliary anode to the positive pole of a DC power supply, connecting the workpiece to the output end of a bipolar pulse power supply, outputting positive and negative alternating voltages, striking an arc with an arc target, and introducing nitrogen, hydrogen and argon.

[0032] In some preferred embodiments, in the arc enhanced plasma process, the flow rate of nitrogen is 50-200 sccm, the flow rate of hydrogen is 50-100 sccm, and the flow rate of argon is 50-200 sccm.

[0033] In some preferred embodiments, in the arc enhanced plasma process, the parameters of the positive and negative alternating voltages are: positive voltage is 20-200V, pulse width is 40μs-1000μs, negative voltage is 200-1200V, pulse width is 40μs-1000μs, positive and negative pulse interval is 20μs-500μs, pulse frequency is 80-10kHz, and duty cycle is 0.2-1.0. The main focus of traditional ion nitriding is ion density and substrate negative bias (attracting nitrogen ion bombardment). Since the plasma is electrically neutral and there are also a large number of electrons, the present invention guides electrons through positive pulses to perform local Joule heating on the substrate, thereby achieving macroscopic low temperature.

[0034] In some preferred embodiments, the arc target may be any one of a Ti target, a Cr target, a TiAl target, or a combination of two or more thereof.

[0035] In some preferred embodiments, the current of the arc target is 40-100A.

[0036] In some preferred embodiments, the current of the DC power supply is 20-80A.

[0037] In some preferred embodiments, the auxiliary anode is columnar or planar, and its height is greater than or equal to the overall height of the workpiece.

[0038] In some embodiments, the plasma nitriding treatment is performed for 60-180 minutes.

[0039] In some embodiments, the low-temperature ion nitriding method further comprises: after subjecting the workpiece to plasma nitriding treatment, cooling the workpiece to below 100° C. under a vacuum state to obtain a nitrided workpiece.

[0040] In some more specific embodiments, the low temperature ion nitriding method comprises the following steps:

[0041] 1) Clean and dry the workpiece, place it in a vacuum chamber, start the mechanical pump and the molecular turbine pump to evacuate to the background vacuum, heat it to 100℃-400℃, and remove the residue in the vacuum chamber;

[0042] 2) Maintain the temperature in the vacuum chamber at 100°C-400°C. When the vacuum degree of the chamber is lower than 2.0×10 -2 pa, high-purity argon gas is introduced to maintain the vacuum chamber pressure of 1-10Pa, the arc target current is kept constant at 40-100A, the baffle is closed, the auxiliary anode is connected to the positive pole of the DC power supply, the current is set to 20-80A, the workpiece is connected to the output end of the bipolar pulse power supply, a negative voltage is output, and the workpiece surface is argon ion etched for 10-60min;

[0043] 3) High-purity nitrogen, high-purity hydrogen and high-purity argon are continuously introduced into the vacuum chamber, the temperature in the vacuum chamber is maintained at 100-400°C, the pressure in the vacuum chamber is maintained at 1-10Pa, the workpiece is connected to the output end of the bipolar pulse power supply, positive and negative alternating voltages are output, the arc target current is maintained constant at 40-100A, the baffle is closed, the auxiliary anode is connected to the positive pole of the DC power supply, the current is set at 20-80A, and plasma nitriding is performed for 60-180min;

[0044] 4) The workpiece is then cooled to below 100° C. in a vacuum state, the vacuum chamber is opened and the workpiece is taken out.

[0045] As another aspect of the technical solution of the present invention, the surface hardness of the nitrided workpiece prepared by the above-mentioned low-temperature ion nitriding method is 1200 HV 0.2 above.

[0046] In summary, the low-temperature ion nitriding method provided by the present invention can realize nitriding at a relatively low temperature (within 100°C to 400°C), adopt cathode arc and auxiliary anode to realize nitrogen atom ionization, and perform ion nitriding on the substrate surface by bipolar pulse bias. The present invention controls the deformation degree of nitriding on the surface of the product by low temperature, obtains high-density plasma by arc-enhanced plasma technology, promotes the ionization of gas, applies bipolar pulse bias to the workpiece, wherein the positive electric field attracts hot electrons, and locally preheats the workpiece surface by pulsed Joule heating, while the sputtering effect of the high-voltage negative electric field introduces high-density defects on the workpiece surface, and increases the diffusion rate of active nitrogen atoms. The nitriding method provided by the present invention can solve the problem of easy deformation of the workpiece during traditional ion nitriding, realize efficient ion nitriding, ensure extremely small or near-zero deformation of the workpiece, and ensure the dimensional accuracy requirements of the product, which is suitable for surface strengthening of cutting tools, molds and metal parts.

[0047] The present invention is further described below by way of examples, but the present invention is not limited to the scope of the examples. The reagents and raw materials used in the following examples are commercially available, and the experimental methods without specific conditions are usually carried out under conventional conditions or under conditions recommended by the manufacturers.

[0048] Example 1

[0049] In this embodiment, the Figure 1 In the device shown in the figure, the M2 high-speed steel sheet is cleaned and dried, and then placed on the workpiece rack 2 in the vacuum chamber 1, evacuated to the background vacuum, and the heating tube 3 is turned on to heat to 100°C, and the temperature in the vacuum chamber is maintained at 100°C. When the vacuum degree of the chamber is lower than 2.0×10 -2 pa, high-purity argon gas (the flow rate of argon gas is 100sccm), the vacuum chamber pressure is maintained at 10Pa, the arc target 4 titanium target current is set to 100A, the baffle 5 is closed, the auxiliary anode 6 is connected to the positive pole of the DC power supply, the current is set to 60A, the workpiece holder 2 is connected to the output end of the bipolar pulse power supply 7, the output voltage is -300V, the pulse frequency is 1kHz, the duty cycle is 0.8, and the surface of the M2 high-speed steel sheet is argon ion etched for 30min.

[0050] Then, high-purity nitrogen, high-purity hydrogen and high-purity argon are continuously introduced into the vacuum chamber 1 (the flow rate of nitrogen is 50 sccm, the flow rate of hydrogen is 50 sccm, and the flow rate of argon is 200 sccm), and the temperature in the vacuum chamber is maintained at 100°C, and the pressure of the vacuum chamber is 10Pa. The workpiece holder 2 is connected to the output end of the bipolar pulse power supply 7, and a positive and negative alternating voltage is output. The voltage waveform diagram is shown in FIG. Figure 2As shown, the positive voltage is 100V, the pulse width is 600μs, the negative voltage is 400V, the pulse width is 100μs, the positive and negative pulse intervals are 50μs, the pulse frequency is 1kHz, the duty cycle is 0.8, the arc target 4 titanium target current is 100A and remains constant, the baffle 5 is closed, the auxiliary anode 6 is connected to the positive pole of the DC power supply, the current is set to 60A, and plasma nitriding is performed for 120 minutes.

[0051] Finally, after the M2 high-speed steel is cooled to below 100° C. in a vacuum state, the vacuum chamber 2 is opened and the M2 high-speed steel is taken out.

[0052] See also Figure 3 , which is a metallographic micrograph of the M2 high-speed steel sheet of this embodiment. After the above-mentioned ion nitriding, the depth of the nitrided layer is between 45-50 μm, there is no white bright layer, and the surface hardness is 1375 HV 0.2 .

[0053] Example 2

[0054] In this embodiment, the Figure 1 In the device shown in the figure, the M2 high-speed steel sheet is cleaned and dried, and then placed on the workpiece rack 2 in the vacuum chamber 1, evacuated to the background vacuum, and the heating tube 3 is turned on to heat to 100°C, and the temperature in the vacuum chamber is maintained at 100°C. When the vacuum degree of the chamber is lower than 2.0×10 -2 pa, introduce high-purity argon gas (the flow rate of argon gas is 200sccm), maintain the vacuum chamber pressure at 10Pa, set the arc target 4 chromium target current to 100A, close the baffle 5, connect the auxiliary anode 6 to the positive pole of the DC power supply, set the current to 60A, connect the workpiece holder 2 to the output end of the bipolar pulse power supply 7, the output voltage is -500V, the pulse frequency is 1kHz, and the duty cycle is 0.6, and perform argon ion etching on the surface of the M2 high-speed steel sheet for 60min.

[0055] Then, high-purity nitrogen, high-purity hydrogen and high-purity argon are continuously introduced into the vacuum chamber 1 (the flow rate of nitrogen is 200sccm, the flow rate of hydrogen is 100sccm, and the flow rate of argon is 100sccm), and the temperature in the vacuum chamber is maintained at 300°C and the pressure of the vacuum chamber is 5Pa. The workpiece holder 2 is connected to the output end of the bipolar pulse power supply 7 to output positive and negative alternating voltages. The voltage waveform diagram is shown in FIG. Figure 2 As shown, the positive voltage is 200V, the pulse width is 600μs, the negative voltage is 300V, the pulse width is 800μs, the positive and negative pulse intervals are 200μs, the pulse frequency is 200Hz, the duty cycle is 0.6, the arc target 4 chromium target current 80A remains constant, the baffle 5 is closed, the auxiliary anode 6 is connected to the positive pole of the DC power supply, the current is set to 40A, and plasma nitriding is performed for 180 minutes.

[0056] Finally, after the M2 high-speed steel is cooled to below 100° C. in a vacuum state, the vacuum chamber 2 is opened and the M2 high-speed steel is taken out.

[0057] See also Figure 4 , which is a metallographic micrograph of the M2 high-speed steel sheet of this embodiment. After the above-mentioned ion nitriding, the depth of the nitrided layer is between 65-70 μm, there is no white bright layer, and the surface hardness is 1513 HV 0.2 .

[0058] Example 3

[0059] In this embodiment, the Figure 1 In the device shown in the figure, the M2 high-speed steel sheet is cleaned and dried, and then placed on the workpiece rack 2 in the vacuum chamber 1, evacuated to the background vacuum, and the heating tube 3 is turned on to heat to 400°C, and the temperature in the vacuum chamber is maintained at 400°C. When the vacuum degree of the chamber is lower than 2.0×10 -2 pa, high-purity argon gas (the flow rate of argon gas is 150sccm), the vacuum chamber pressure is maintained at 1Pa, the arc target 4 titanium target current is set to 40A, the baffle 5 is closed, the auxiliary anode 6 is connected to the positive pole of the DC power supply, the current is set to 20A, the workpiece holder 2 is connected to the output end of the bipolar pulse power supply 7, the output voltage is -1200V, the pulse frequency is 80Hz, and the duty cycle is 1.0, and the surface of the M2 high-speed steel sheet is argon ion etched for 10min.

[0060] Then, high-purity nitrogen, high-purity hydrogen and high-purity argon are continuously introduced into the vacuum chamber 1 (the flow rate of nitrogen is 100 sccm, the flow rate of hydrogen is 70 sccm, and the flow rate of argon is 50 sccm), the temperature in the vacuum chamber is maintained at 400°C, the pressure of the vacuum chamber is 1Pa, and the workpiece holder 2 is connected to the output end of the bipolar pulse power supply 7 to output positive and negative alternating voltages. The voltage waveform diagram is shown in FIG. Figure 2 As shown, the positive voltage is 20V, the pulse width is 40μs, the negative voltage is 1200V, the pulse width is 40μs, the positive and negative pulse intervals are 20μs, the pulse frequency is 10kHz, the duty cycle is 1.0, the arc target 4 titanium target current 40A remains constant, the baffle 5 is closed, the auxiliary anode 6 is connected to the positive pole of the DC power supply, the current is set to 20A, and plasma nitriding is performed for 60 minutes.

[0061] Finally, after the M2 high-speed steel is cooled to below 100° C. in a vacuum state, the vacuum chamber 2 is opened and the M2 high-speed steel is taken out.

[0062] See also Figure 5 , which is a metallographic micrograph of the M2 high-speed steel sheet of this embodiment. After the above-mentioned ion nitriding, the depth of the nitrided layer is between 30-35 μm, there is no white bright layer, and the surface hardness is 1219 HV 0.2 .

[0063] Example 4

[0064] In this embodiment, the Figure 1In the device shown in the figure, the M2 high-speed steel sheet is cleaned and dried, and then placed on the workpiece rack 2 in the vacuum chamber 1, evacuated to the background vacuum, and the heating tube 3 is turned on to heat to 200°C, and the temperature in the vacuum chamber is maintained at 200°C. When the vacuum degree of the chamber is lower than 2.0×10 -2 pa, high-purity argon gas (the flow rate of argon gas is 120sccm), the vacuum chamber pressure is maintained at 3Pa, the arc target 4 titanium aluminum target current is set to 80A, the baffle 5 is closed, the auxiliary anode 6 is connected to the positive pole of the DC power supply, the current is set to 80A, the workpiece holder 2 is connected to the output end of the bipolar pulse power supply 7, the output voltage is -200V, the pulse frequency is 10kHz, and the duty cycle is 0.2, and the surface of the M2 high-speed steel sheet is argon ion etched for 40min.

[0065] Then, high-purity nitrogen, high-purity hydrogen and high-purity argon are continuously introduced into the vacuum chamber 1 (the flow rate of nitrogen is 200sccm, the flow rate of hydrogen is 100sccm, and the flow rate of argon is 200sccm), the temperature in the vacuum chamber is maintained at 200°C, and the pressure of the vacuum chamber is 3Pa. The workpiece holder 2 is connected to the output end of the bipolar pulse power supply 7 to output positive and negative alternating voltages. The voltage waveform diagram is shown in FIG. Figure 2 As shown, the positive voltage is 100V, the pulse width is 1000μs, the negative voltage is 200V, the pulse width is 1000μs, the positive and negative pulse intervals are 500μs, the pulse frequency is 80Hz, the duty cycle is 0.2, the arc target 4 titanium aluminum target current is 80A and remains constant, the baffle 5 is closed, the auxiliary anode 6 is connected to the positive pole of the DC power supply, the current is set to 80A, and plasma nitriding is performed for 150 minutes.

[0066] Finally, after the M2 high-speed steel is cooled to below 100° C. in a vacuum state, the vacuum chamber 2 is opened and the M2 high-speed steel is taken out.

[0067] See also Figure 6 , which is a metallographic micrograph of the M2 high-speed steel sheet of this embodiment. After the above-mentioned ion nitriding, the depth of the nitrided layer is between 70-80 μm, there is no white bright layer, and the surface hardness is 1462 HV 0.2 .

[0068] Comparative Example 1

[0069] In this embodiment, the Figure 1 In the device shown in the figure, the M2 high-speed steel sheet is cleaned and dried, and then placed on the workpiece rack 2 in the vacuum chamber 1, evacuated to the background vacuum, and the heating tube 3 is turned on to heat to 100°C, and the temperature in the vacuum chamber is maintained at 100°C. When the vacuum degree of the chamber is lower than 2.0×10 -2pa, high-purity argon gas (the flow rate of argon gas is 100sccm), the vacuum chamber pressure is maintained at 10Pa, the arc target 4 titanium target current is set to 100A, the baffle 5 is closed, the auxiliary anode 6 is connected to the positive pole of the DC power supply, the current is set to 60A, the workpiece holder 2 is connected to the output end of the bipolar pulse power supply 7, the output voltage is -300V, the pulse frequency is 1kHz, the duty cycle is 0.8, and the surface of the M2 high-speed steel sheet is argon ion etched for 30min.

[0070] Subsequently, high-purity nitrogen, high-purity hydrogen and high-purity argon (the flow rate of nitrogen is 50sccm, the flow rate of hydrogen is 50sccm, and the flow rate of argon is 200sccm) are continuously introduced into the vacuum chamber 1, and the temperature in the vacuum chamber is maintained at 100°C, the air pressure in the vacuum chamber is 10Pa, the workpiece holder 2 is connected to the output end of the bipolar pulse power supply 7, the output voltage is -400V, the pulse width is 100μs, the pulse frequency is 1kHz, the duty cycle is 0.1, the arc target 4 titanium target current 100A is kept constant, the baffle 5 is closed, the auxiliary anode 6 is connected to the positive pole of the DC power supply, the current is set to 60A, and plasma nitriding is carried out for 120 minutes.

[0071] Finally, after the M2 high-speed steel is cooled to below 100° C. in a vacuum state, the vacuum chamber 2 is opened and the M2 high-speed steel is taken out.

[0072] Compared with Example 1, no positive voltage is applied to the workpiece in Comparative Example 1, and electron bombardment is lacking, resulting in the surface layer of the workpiece failing to reach the temperature required for nitriding. Figure 7 , which is a metallographic micrograph of the M2 high-speed steel sheet of this comparative example. After the above-mentioned ion nitriding, the M2 high-speed steel has no nitriding layer, and the surface hardness is 850HV 0.2 , which is equivalent to M2 high speed steel without ion nitriding.

[0073] In addition, the inventors of this case also referred to the aforementioned embodiments and conducted experiments with other raw materials, process operations, and process conditions described in this specification, and obtained relatively ideal results.

[0074] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A method for low temperature ion nitriding, characterized in that: include: Under selected temperature conditions, an arc-enhanced glow discharge process is used to perform ion etching on the surface of a workpiece, and then an arc-enhanced plasma process is used to perform plasma nitriding on the workpiece to obtain a nitrided workpiece; wherein, in the arc-enhanced plasma process, positive and negative alternating voltages are applied to the workpiece.

2. The method according to claim 1, characterized in that include: Placing the workpiece in a reaction chamber, evacuating the reaction chamber to a background vacuum, heating the chamber to a selected temperature, and then performing the ion etching process; And / or, the ion etching treatment time is 10-60 minutes.

3. The method according to claim 2, characterized in that The selected temperature is 100°C-400°C; And / or, the gas pressure of the reaction chamber is 1-10Pa; And / or, the heating method includes heating with an infrared electric heating tube.

4. The method according to claim 1, characterized in that: The arc enhanced glow discharge process comprises: connecting the auxiliary anode to the positive electrode of a DC power supply, connecting the workpiece to the output end of a pulse power supply, outputting a negative voltage, striking an arc with an arc target, and introducing argon gas; And / or, the arc enhanced plasma process includes: connecting the auxiliary anode to the positive pole of a DC power supply, connecting the workpiece to the output end of a bipolar pulse power supply, outputting positive and negative alternating voltages, striking an arc with an arc target, and introducing nitrogen, hydrogen and argon.

5. The method according to claim 4, characterized in that In the arc enhanced glow discharge process, a bipolar pulse power supply is used, the negative voltage is 200-1200V, the pulse frequency is 80-10kHz, and the duty cycle is 0.2-1.0; and / or, in the arc enhanced glow discharge process, the flow rate of the argon gas is 100-200 sccm; and / or, in the arc enhanced plasma process, the flow rate of the nitrogen gas is 50-200 sccm, the flow rate of the hydrogen gas is 50-100 sccm, and the flow rate of the argon gas is 50-200 sccm; And / or, in the arc enhanced plasma process, the parameters of the positive and negative alternating voltages are: positive voltage is 20-200V, pulse width is 40μs-1000μs, negative voltage is 200-1200V, pulse width is 40μs-1000μs, positive and negative pulse interval is 20μs-500μs, pulse frequency is 80-10kHz, and duty cycle is 0.2-1.

0.

6. The method according to claim 4, characterized in that The arc target is any one of a Ti target, a Cr target, and a TiAl target, or a combination of two or more thereof; And / or, the current of the arc target is 40-100A.

7. The method according to claim 4, characterized in that The current of the DC power supply is 20-80A; And / or, the auxiliary anode is columnar or planar, and its height is greater than or equal to the overall height of the workpiece.

8. The method according to claim 1, characterized in that The plasma nitriding treatment time is 60-180 minutes.

9. The method according to claim 1, characterized in that: Also includes: After the workpiece is subjected to plasma nitriding treatment, it is cooled to below 100° C. in a vacuum state to obtain a nitrided workpiece.

10. A nitrided workpiece prepared by the method according to any one of claims 1 to 9, characterized in that: The surface hardness of the nitrided workpiece is 1200 HV 0.2 above.

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