Preparation method of superhard high-entropy alloy nitride coating on surface of alloy material

Abstract

The invention discloses a preparation method of a superhard high-entropy alloy nitride coating on the surface of an alloy material, which comprises the following steps: taking an alloy workpiece, and carrying out glow cleaning on the alloy workpiece in a vacuum environment; the cleaned alloy workpiece is placed in an argon environment, the air pressure of a vacuum chamber ranges from 0.3 Pa to 1 Pa, an AlCrTiVZr target material is sputtered to the alloy workpiece through HiPIMS, the deposition time ranges from 1 min to 10 min, and an AlCrTiVZr over-plating layer is gradually formed on the surface of the alloy workpiece; and the sputtering condition is kept, nitrogen is introduced into the reaction environment, the flow value of the nitrogen ranges from 4 sccm to 40 sccm, the deposition time ranges from 60 min to 180 min, the AlCrTiVZr over-plating layer is deposited on the surface of the alloy workpiece, and the high-entropy alloy nitride coating is formed. The problems that a columnar crystal microstructure on the surface of a common high-entropy alloy nitride coating is loose and many micropores exist are solved, the hardness of the coating is improved to 41.8 GPa, and the surface roughness of the coating is maintained to be 2 nm or below.

Description

Technical Field

[0001] The invention relates to the field of coating adhesion, and in particular to a method for preparing a superhard high entropy alloy nitride coating on the surface of an alloy material. Background Art

[0002] At present, the use of multi-principal high entropy alloy nitrides as coating materials can further improve the comprehensive performance of alloy materials, such as a high entropy alloy nitride (AlCrTiVZr)N coating, which has the same scientific concept as high entropy alloys. Compared with traditional nitrides, (AlCrTiVZr)N coatings have high entropy effects in thermodynamics, slow diffusion effects in kinetics, lattice distortion effects in structure, and cocktail effects in performance, which are conducive to the formation of simple solid solutions on the surface of alloy materials, and make the structure tend to be nano-sized or even amorphous, thus having excellent properties such as high hardness, high work hardening, high wear resistance, high thermal stability and high corrosion resistance.

[0003] However, the existing problem is that the commonly used preparation technology for high entropy alloy nitride (AlCrTiVZr)N coating is magnetron sputtering (HiPIMS). Magnetron sputtering has many advantages such as low temperature deposition, smooth surface, large coating area, and no macroscopic particles. However, due to the low metal ionization rate (<5%) of conventional magnetron sputtering, most of the sputtered metal exists in the form of atoms. The (AlCrTiVZr)N coating attached to the alloy material often has a loose columnar crystal microstructure and a large number of micropores, which leads to a decrease in the hardness of the film (less than 15GPa).

[0004] It can be seen that how to better adhere the high entropy alloy nitride (AlCrTiVZr) N coating to the surface of the alloy material and solve the problems of loose columnar crystal microstructure and many micropores on the coating surface is the key technical bottleneck in its further industrial application. Summary of the invention

[0005] The purpose of the present invention is to provide a method for preparing a superhard high entropy alloy nitride coating on the surface of an alloy material, so as to solve the technical problems of rough surface and low hardness of the high entropy alloy nitride (AlCrTiVZr) N coating in the prior art.

[0006] In order to solve the above technical problems, the present invention specifically provides the following technical solutions:

[0007] The present invention provides a method for preparing a superhard high entropy alloy nitride coating on the surface of an alloy workpiece, comprising the following steps:

[0008] Taking an alloy workpiece, performing preliminary cleaning on the alloy workpiece, and performing glow cleaning on the alloy workpiece in a vacuum environment;

[0009] The cleaned alloy workpiece is placed in an argon environment with a vacuum chamber pressure of 0.3 Pa to 1 Pa, and an AlCrTiVZr target is sputtered onto the alloy workpiece by HiPIMS for a deposition time of 1 min to 10 min, so that an AlCrTiVZr over-plating layer is gradually formed on the surface of the alloy workpiece;

[0010] The sputtering conditions are maintained, nitrogen is introduced into the reaction environment, the flow rate of the nitrogen is 4 sccm-40 sccm, the deposition time is 60 min-180 min, and the AlCrTiVZr over-plating layer is deposited on the surface of the alloy workpiece to form a high entropy alloy nitride coating.

[0011] As a preferred solution of the present invention, after the HiPIMS power supply is turned on, its parameters are adjusted to a voltage value of -450V to -1000V, a pulse frequency of 50hz to 500hz, and a pulse width of 50 to 500μs;

[0012] The parameters provided to the alloy workpiece by an external power supply are: voltage value -50V to -300V, frequency 20Khz to 100Khz, and duty cycle 50% to 90%.

[0013] As a preferred solution of the present invention, after the HiPIMS power supply is turned on, its parameters are adjusted to a voltage of -550V to -650V, a frequency of 100hz to 250hz, and a pulse width of 100μs to 250μs;

[0014] The parameters provided to the alloy workpiece by an external power supply are: voltage of -50V to -200V, frequency of 20Khz to 60Khz, and duty cycle of 70% to 90%.

[0015] As a preferred embodiment of the present invention, the glow cleaning comprises the following steps:

[0016] Use a mechanical pump and a molecular pump to evacuate the vacuum chamber so that the pressure in the vacuum chamber is less than or equal to 5×10-3Pa;

[0017] Introduce argon gas into the vacuum chamber and adjust the gas flow rate to keep the vacuum chamber pressure at 1-3 Pa;

[0018] The alloy workpiece is provided with a negative bias voltage of -400 to -1200V, a frequency of 20Khz to 100Khz, and a duty cycle of 50% to 90% by an external power supply, and then cleaning is started. The glow cleaning is completed after cleaning for 10 to 20 minutes.

[0019] As a preferred embodiment of the present invention, during the glow cleaning process, the air pressure in the vacuum chamber is 1.2 Pa;

[0020] The parameters provided to the alloy workpiece by the external power supply are preferably: negative bias voltage -800V, frequency 40Khz, and duty cycle 90%.

[0021] As a preferred solution of the present invention, the flow rate of the nitrogen gas is 8 sccm to 20 sccm.

[0022] As a preferred solution of the present invention, the deposition time of the AlCrTiVZr over-plating layer on the surface of the alloy workpiece is 60 minutes.

[0023] As a preferred embodiment of the present invention, the hardness of the high entropy alloy nitride coating is 32.1 to 41.8 GPa.

[0024] As a preferred embodiment of the present invention, the surface roughness of the high entropy alloy nitride coating is 0.64-1.51 nm.

[0025] As a preferred solution of the present invention, the alloy workpiece is an alloy cutting tool.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] The present invention mainly adopts HiPIMS technology to generate a highly ionized plasma film-forming environment without large particles, strengthen the bombardment of high-energy particles on the film, promote the repeated nucleation rate and migration rate of grains, and then inhibit the formation of columnar crystal structures throughout the thickness of the film, improve the density and uniformity of the film, as well as the hardness, wear resistance and corrosion resistance of the film, thereby solving the technical problems of rough surface and low hardness of high-entropy alloy nitride coatings;

[0028] The present invention limits the preparation conditions of the high entropy alloy nitride coating, obtains a coating with a hardness that can reach a superhard level of 41.8 GPa and a surface roughness reduced to less than 2 nm, and the coating can be attached to alloy workpieces such as alloy cutting tools, thereby broadening the application scope of the high entropy alloy nitride coating and further obtaining a cutting tool with high hardness and low roughness;

[0029] The average power of the HiPIMS used in the present invention is comparable to the power of conventional magnetron sputtering, and the sputtering target will not be overheated due to the use of the HiPIMS, thereby increasing the cooling requirements thereof. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the implementation methods of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for the implementation methods or the description of the prior art. Obviously, the drawings in the following description are only exemplary, and for ordinary technicians in this field, other implementation drawings can be derived from the provided drawings without creative work.

[0031] Figure 1 The present invention provides a schematic flow chart of a method for preparing a superhard high entropy alloy nitride coating on the surface of an alloy material.

[0032] Figure 2 Provide a hardness curve of the high entropy alloy nitride coating in Example 1 of the present invention;

[0033] Figure 3 The present invention provides a cross-sectional morphology of the high entropy alloy nitride coating in Example 1;

[0034] Figure 4 Provide a surface morphology of the high entropy alloy nitride coating in Example 1 of the present invention;

[0035] Figure 5 Provide a hardness curve of the high entropy alloy nitride coating in Example 2 of the present invention;

[0036] Figure 6 The present invention provides a cross-sectional morphology of a high entropy alloy nitride coating in Example 2;

[0037] Figure 7 A surface morphology image of the high entropy alloy nitride coating in Example 2 is provided for the present invention. DETAILED DESCRIPTION

[0038] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0039] like Figure 1 As shown, the present invention provides a method for preparing a superhard high entropy alloy nitride coating on the surface of an alloy material, comprising the following steps:

[0040] Step 1, taking an alloy workpiece, preparing a method for preparing a superhard high entropy alloy nitride coating on the surface of the alloy material, and performing glow cleaning on the alloy workpiece in a vacuum environment;

[0041] Step 2, placing the cleaned alloy workpiece in an argon environment with a vacuum chamber pressure of 0.3Pa-1Pa, sputtering AlCrTiVZr target material to the alloy workpiece by HiPIMS, with a deposition time of 1min-10min, and gradually forming an AlCrTiVZr over-plating layer on the surface of the alloy workpiece;

[0042] Step 3: maintaining the sputtering conditions, introducing nitrogen into the reaction environment, wherein the flow rate of the nitrogen is 4 sccm-40 sccm, and the deposition time is 60 min-180 min. The AlCrTiVZr over-plating layer is deposited on the surface of the alloy workpiece to form a high entropy alloy nitride coating.

[0043] Among them, the high entropy alloy nitride coating refers to (AlCrTiVZr)N coating.

[0044] Specifically, in step 1, preliminary cleaning of the surface of the alloy workpiece refers to degreasing, derusting and cleaning the alloy workpiece to be coated, followed by drying to remove dust, ionic impurities or organic solutions on the surface of the alloy workpiece.

[0045] In the present invention, the alloy workpiece can be selected as a hard alloy tool (YT15) with a size of 15mm*15mm*5mm as the base. The degreasing, rust removal and cleaning processes are all carried out in a conventional manner, which will not be repeated here.

[0046] At the same time, the cleaned alloy tool is placed in a vacuum chamber, the vacuum chamber is evacuated, and then the alloy tool is glow cleaned;

[0047] The process of glow cleaning (plasma cleaning) in this embodiment is as follows:

[0048] 1. Use mechanical pump and molecular pump to evacuate the vacuum chamber so that the pressure in the vacuum chamber is less than or equal to 5×10 -3 Pa;

[0049] 2. Then introduce argon gas into the vacuum chamber and adjust the gas flow rate to keep the vacuum chamber pressure at 1-3 Pa;

[0050] 3. Provide the alloy tool with a negative bias voltage of -400 to -1200 V, a frequency of 20 Khz to 100 Khz, and a duty cycle of 50% to 90% through an external power supply, and then start cleaning. Complete the glow cleaning after cleaning for 10 to 20 minutes.

[0051] The pressure in the vacuum chamber is preferably maintained at 1.2 Pa, and the parameters provided to the alloy tool by the external power supply are preferably: negative bias voltage -800V, frequency 40Khz, duty cycle 90%, and the cleaning time is preferably 10 minutes.

[0052] In step 2, after the glow cleaning is completed, the argon gas flow rate is adjusted so that the vacuum chamber pressure is 0.3Pa~1Pa, the HiPIMS power supply is turned on and the parameters are adjusted to: voltage value -450V~-1000V, pulse frequency is 50hz~500hz, and pulse width is 50~500μs; the parameters provided to the alloy tool by the external power supply are: voltage value -50V~-300V, frequency 20Khz~100Khz, duty cycle 50%~90%; then the AlCrTiVZr target is sputtered, and after a deposition time of 1min-10min, an AlCrTiVZr over-plating layer is formed on the surface of the alloy tool;

[0053] In this processing step, the adjustment parameters of the HiPIMS power supply are preferably: voltage of -550V to -650V, frequency of 100hz to 250hz, and pulse width of 100μs to 250μs; the preferred parameters provided to the alloy tool by the external power supply are: voltage of -50V to -200V, frequency of 20Khz to 60Khz, and duty cycle of 70% to 90%.

[0054] In step 4, the existing sputtering conditions are kept unchanged, and nitrogen gas is gradually introduced as a reaction gas with a flow rate of 4 sccm-40 sccm and a deposition time of 60 min-180 min, ultimately forming a high entropy alloy nitride coating on the surface of the alloy tool.

[0055] In this step, the flow rate of nitrogen is preferably 8 sccm to 20 sccm; and the deposition time is preferably 60 min.

[0056] The (AlCrTiVZr)N coating prepared by the method disclosed in the present invention has a single FCC crystal structure and tends to be nano-sized, and its hardness can reach a superhard level of 41.8GPa, and the surface roughness is reduced to below 2nm, which is far beyond the expectations of those skilled in the art. In addition, the (AlCrTiVZr)N coating prepared by HiPIMS does not have the problems of loose columnar crystal microstructure and many micropores on the surface, and the film hardness is high. Its performance is far better than that of the (AlCrTiVZr)N coating prepared by conventional magnetron sputtering and high entropy alloy nitride coatings of other systems.

[0057] The HiPIMS technology used in the present invention uses high peak power (kw / cm2) and low duty cycle (1-5%) to produce a highly ionized plasma film-forming environment without large particles, strengthen the bombardment of high-energy particles on the film, promote the repeated nucleation rate and migration rate of grains, and then inhibit the formation of columnar crystal structures throughout the thickness of the film, improve the density and uniformity of the film, as well as the hardness, wear resistance and corrosion resistance of the film. In addition, the average power of HiPIMS is equivalent to that of traditional magnetron sputtering, and the sputtering target will not be overheated due to the use of HiPIMS, which will increase its cooling requirements.

[0058] The high entropy alloy nitride coating is further described below by way of examples:

[0059] Embodiment 1.

[0060] (1) A carbide tool (YT15) with a size of 15 mm*15 mm*5 mm was selected as the substrate, and the carbide tool was degreased, derusted, and cleaned, then dried and placed in a vacuum chamber;

[0061] (2) Glow cleaning:

[0062] Use mechanical pump and molecular pump to evacuate the vacuum chamber so that the pressure inside the chamber is less than or equal to 5×10 -3 When the vacuum chamber is at 1.2 Pa, Ar is introduced into the vacuum chamber, and the gas flow rate is adjusted to make the pressure in the chamber 1.2 Pa. The substrate is loaded with a negative bias voltage of -800 V, the duty cycle is 90%, the frequency is 40 Khz, and the etching and cleaning of the substrate is completed by glow discharge, and the processing time is 10 min.

[0063] (3) Transition layer deposition:

[0064] After the substrate glow cleaning is completed, the Ar gas flow rate is adjusted to make the chamber pressure 0.4Pa, the HiPIMS power supply is started, and the AlCrTiVZr target is sputtered by HiPIMS to deposit the transition layer AlCrTiVZr coating. The specific parameters of HiPIMS are: voltage value -560V, pulse frequency is 200hz, and pulse width is 100μs. The specific parameters of negative bias are: voltage value -75V, frequency 40Khz, duty cycle 90%, and deposition time 1min.

[0065] (4) Formation of high entropy nitride (AlCrTiVZr) N coating: After the transition layer is completed, N2 is slowly introduced into the chamber with a gas flow rate of 12 sccm to form a high entropy nitride (AlCrTiVZr) N coating by reactive sputtering deposition; the specific parameters of HiPIMS are: voltage value -560V, pulse frequency 200hz, pulse width 100μs; the specific parameters of negative bias voltage are: voltage value -75V, frequency 40Khz, duty cycle 90%. The deposition time is 60min.

[0066] The following characterizes Example 1:

[0067] (1) The nanohardness of the above coatings was measured by nanoindentation method.

[0068] like Figure 2 The hardness curve at any three points of the coating is shown. The hardness values ​​of the 100nm-200nm indentation area are selected and the average value is taken. The hardness is 41.8GPa;

[0069] (2) The cross-sectional morphology of the above coating was observed using a scanning electron microscope (SEM).

[0070] like Figure 3 The cross-sectional morphology of the coating is shown, and the coating is dense and has no penetrating columnar crystal structure;

[0071] (3) The surface morphology and roughness of the above coatings were measured using an atomic force microscope (AFM) with a test area of ​​5 μm×5 μm.

[0072] like Figure 4 As shown, its surface roughness is 0.64nm.

[0073] Embodiment 2

[0074] The substrate used in this embodiment is exactly the same as that in the first embodiment, and steps 1 and 2 are also the same as those in the first embodiment, except that:

[0075] (3) is basically the same as step 3 in Example 1; the difference is that when the transition layer AlCrTiVZr coating is prepared by HiPIMS, the specific parameters of HiPIMS are: voltage value -700V, pulse frequency is 80hz, pulse width is 80μs. The specific parameters of negative bias voltage are: voltage value -150V, frequency is 40Khz, and duty cycle is 90%.

[0076] (4) is basically the same as step 4 in Example 1; the difference is that when using HiPIMS to prepare the transition layer (AlCrTiVZr) N coating, the specific parameters of HiPIMS are: voltage value -700V, pulse frequency 80hz, pulse width 80μs. The specific parameters of negative bias are: voltage value -150V, frequency 40Khz, duty cycle 90%. The N2 flow rate is 30sccm.

[0077] The following characterizes Example 2:

[0078] (1) The nanohardness of the above coatings was measured by nanoindentation method.

[0079] like Figure 5 The hardness curve at any three points is shown in the formula. The hardness values ​​of the 100nm-200nm indentation area are selected and the average value is taken. The hardness is 32.1GPa.

[0080] (2) The cross-sectional morphology of the above coating was observed using a scanning electron microscope (SEM).

[0081] like Figure 6 The cross-sectional morphology of the coating is shown, and the coating is dense and has no penetrating columnar crystal structure.

[0082] (3) The surface morphology and roughness of the above coatings were measured using an atomic force microscope (AFM) with a test area of ​​5 μm*5 μm.

[0083] like Figure 7 As shown, its surface roughness is 1.51nm.

[0084] By comparing Example 1 with Example 2, it can be seen that both of them show a dense coating with no penetrating columnar crystal structure, which solves the problem of loose columnar crystal microstructure and many micropores on the surface of general high-entropy alloy nitride coatings; at the same time, by limiting the specific parameters of HiPIMS, a method that can balance the hardness and roughness of the coating is obtained, and the coating hardness is increased to 41.8 GPa. The surface roughness is maintained below 2 nm, which meets the use requirements of the cutting tool and expands the application range of high-entropy alloy nitride coatings.

[0085] The above embodiments are only exemplary embodiments of the present application and are not intended to limit the present application. The protection scope of the present application is defined by the claims. Those skilled in the art may make various modifications or equivalent substitutions to the present application within the essence and protection scope of the present application, and such modifications or equivalent substitutions shall also be deemed to fall within the protection scope of the present application.

Claims

1. A method for preparing a superhard high entropy alloy nitride coating on the surface of an alloy material, characterized in that: The steps include: Taking an alloy workpiece, and performing glow cleaning on the alloy workpiece in a vacuum environment; The cleaned alloy workpiece is placed in an argon environment with a vacuum chamber pressure of 0.3 Pa to 1 Pa, and an AlCrTiVZr target is sputtered onto the alloy workpiece by HiPIMS for a deposition time of 1 min to 10 min, so that an AlCrTiVZr over-plating layer is gradually formed on the surface of the alloy workpiece; The sputtering conditions are maintained, nitrogen is introduced into the reaction environment, the flow rate of the nitrogen is 4 sccm-40 sccm, the deposition time is 60 min-180 min, and the AlCrTiVZr over-plating layer is deposited on the surface of the alloy workpiece to form a high entropy alloy nitride coating.

2. The method for preparing a superhard high entropy alloy nitride coating on the surface of an alloy material according to claim 1, characterized in that: After the HiPIMS power supply is turned on, its parameters are adjusted to a voltage value of -450V to -1000V, a pulse frequency of 50hz to 500hz, and a pulse width of 50 to 500μs; The parameters provided to the alloy workpiece by an external power supply are: voltage value -50V to -300V, frequency 20Khz to 100Khz, and duty cycle 50% to 90%.

3. The method for preparing a superhard high entropy alloy nitride coating on the surface of an alloy material according to claim 1, characterized in that: After the HiPIMS power supply is turned on, its parameters are adjusted to a voltage of -550V to -650V, a frequency of 100 Hz to 250 Hz, and a pulse width of 100 μs to 250 μs; The parameters provided to the alloy workpiece by an external power supply are: voltage of -50V to -200V, frequency of 20Khz to 60Khz, and duty cycle of 70% to 90%.

4. The method for preparing a superhard high entropy alloy nitride coating on the surface of an alloy material according to claim 1, characterized in that: The glow cleaning comprises the following steps: Use a mechanical pump and a molecular pump to evacuate the vacuum chamber so that the pressure in the vacuum chamber is less than or equal to 5×10-3Pa; Introduce argon gas into the vacuum chamber and adjust the gas flow rate to keep the vacuum chamber pressure at 1-3 Pa; The alloy workpiece is provided with a negative bias voltage of -400 to -1200V, a frequency of 20Khz to 100Khz, and a duty cycle of 50% to 90% by an external power supply, and then cleaning is started. The glow cleaning is completed after cleaning for 10 to 20 minutes.

5. The method for preparing a superhard high entropy alloy nitride coating on the surface of an alloy material according to claim 4, characterized in that: During the glow cleaning process, the air pressure in the vacuum chamber is 1.2 Pa; The parameters provided to the alloy workpiece by the external power supply are preferably: negative bias voltage -800V, frequency 40Khz, and duty cycle 90%.

6. The method for preparing a superhard high entropy alloy nitride coating on the surface of an alloy material according to claim 1, characterized in that: The flow rate of the nitrogen gas is 8 sccm to 20 sccm.

7. The method for preparing a superhard high entropy alloy nitride coating on the surface of an alloy material according to claim 1, characterized in that: The deposition time of the AlCrTiVZr over-plating layer on the surface of the alloy workpiece is 60 minutes.

8. The method for preparing a superhard high entropy alloy nitride coating on the surface of an alloy material according to claim 1, characterized in that: The hardness of the high entropy alloy nitride coating is 32.1-41.8 GPa.

9. The method for preparing a superhard high entropy alloy nitride coating on the surface of an alloy material according to claim 1, characterized in that: The surface roughness of the high entropy alloy nitride coating is 0.64-1.51 nm.

10. The method for preparing a superhard high entropy alloy nitride coating on the surface of an alloy material according to claim 1, characterized in that: The alloy workpiece is an alloy cutting tool.

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