CN111560582A

CN111560582A - Method for manufacturing superhard high-entropy alloy nitride coating on alloy cutter

Info

Publication number: CN111560582A
Application number: CN202010418122.8A
Authority: CN
Inventors: 夏原; 许亿; 李光
Original assignee: Institute of Mechanics of CAS
Current assignee: Institute of Mechanics of CAS
Priority date: 2020-05-18
Filing date: 2020-05-18
Publication date: 2020-08-21

Abstract

The invention provides a method for manufacturing a superhard high-entropy alloy nitride coating on an alloy cutter, which comprises the following steps: respectively carrying out oil removal, rust removal and cleaning treatment on the alloy cutter to be coated, and then drying; placing the cleaned alloy cutter in a vacuum chamber, vacuumizing the vacuum chamber, and then performing glow cleaning on the alloy cutter; after glow cleaning is finished, adjusting argon flow, starting a HiPIMS power supply and adjusting preset parameters; providing preset parameters for the alloy cutter through an external power supply; then sputtering AlCrTiVZr target material, and forming an AlCrTiVZr overplate layer on the surface of the alloy cutter after the deposition time is 1-10 min; keeping the existing sputtering condition unchanged, gradually introducing reaction gas nitrogen, and forming a high-entropy alloy nitride coating on the surface of the alloy cutter after deposition. The (AlCrTiVZr) N coating prepared by the invention is a single FCC crystal structure and tends to be nanocrystallized, the hardness can reach the superhard level of 41.8GPa, and the surface roughness is reduced to below 2nm, which is far beyond the expectation range of the technicians in the field.

Description

Method for manufacturing superhard high-entropy alloy nitride coating on alloy cutter

Technical Field

The invention relates to the field of metal coatings, in particular to a preparation method of a superhard (AlCrTiVZr) N high-entropy alloy nitride coating.

Background

With the rapid development of cutting processing technology, high-speed and high-power machine tools and difficult-to-process materials are widely used. Meanwhile, the enhancement of national environmental protection consciousness further improves the use cost of the cutting cooling lubricating fluid. Therefore, the cutting processing technology puts higher requirements on the material performance of the cutting tool. The appearance of the cutter coating relieves the contradiction between the rapid development of the cutting processing technology and the lagging performance of the cutting cutter material. The selection of a proper cutter coating can realize the cutting of difficult-to-machine materials such as high-temperature alloy, titanium alloy, particle reinforced composite materials and the like on one hand, and can also reduce the consumption of the cutter material on the other hand and improve the dimensional precision and the surface quality of the machined materials on the other hand.

The material selection thought of the traditional coating is broken through, and the comprehensive performance of the cutter can be greatly improved by adopting the multi-principal-element high-entropy alloy nitride as the coating material. High entropy alloy nitride (AlCrTiVZr) N coatings have the same scientific concept as high entropy alloys. Compared with the traditional nitride, the (AlCrTiVZr) N coating has high entropy effect in thermodynamics, slow diffusion effect in kinetics, lattice distortion effect in structure and cocktail effect in performance. The four effects effectively reduce the formation of intermetallic brittle compounds in the (AlCrTiVZr) N coating, are beneficial to forming simple solid solution, and make the structure tend to be nano-sized or even non-crystallized, thereby having excellent performances such as high hardness, high work hardening, high wear resistance, high thermal stability, high corrosion resistance and the like.

At present, a commonly used preparation technology of the high-entropy alloy nitride (AlCrTiVZr) N coating is magnetron sputtering (HiPIMS). Magnetron sputtering has the advantages of low-temperature deposition, smooth surface, large coating area, no macroscopic particles and the like, however, due to the lower metal ionization rate (< 5%) of conventional magnetron sputtering, most of sputtered metal exists in the form of atoms, and the prepared (AlCrTiVZr) N coating often has a loose columnar crystal microstructure and a large number of micropores, so that the hardness of the film is reduced (less than 15 GPa). Therefore, magnetron sputtering preparation (AlCrTiVZr) N coating inevitably has some defects and becomes a key technical bottleneck in further industrial application.

Disclosure of Invention

The object of the invention herein is to provide a new method for the preparation of ultra hard (AlCrTiVZr) N coatings, with which ultra hard coatings with ultra high hardness, low surface roughness and dense microstructure can be prepared.

Specifically, the invention provides a method for manufacturing a superhard high-entropy alloy nitride coating on an alloy cutter, which comprises the following steps:

step 100, respectively carrying out oil removal, rust removal and cleaning treatment on an alloy cutter to be coated, and then drying;

200, placing the cleaned alloy cutter in a vacuum chamber, vacuumizing the vacuum chamber, and then performing glow cleaning on the alloy cutter;

step 300, after glow cleaning is finished, adjusting the flow of argon gas to make the air pressure of the vacuum chamber be 0.3-1 Pa, starting a HiPIMS power supply and adjusting parameters as follows: the voltage value is-450V to-1000V, the pulse frequency is 50hz to 500hz, and the pulse width is 50 to 500 mu s; the parameters provided for the alloy cutter by an external power supply are as follows: the voltage value is-50V to-300V, the frequency is 20Khz to 100Khz, and the duty ratio is 50 percent to 90 percent; then sputtering AlCrTiVZr target material, and forming an AlCrTiVZr overplate layer on the surface of the alloy cutter after the deposition time is 1-10 min;

and step 400, keeping the existing sputtering condition unchanged, gradually introducing reaction gas nitrogen with the flow value of 4-40 sccm, depositing for 60-180 min, and finally forming a high-entropy alloy nitride coating on the surface of the alloy cutter.

In one embodiment of the present invention, in the step 200, the glow cleaning process for the alloy cutter is as follows:

step 201, utilizing a mechanical pump and a molecular pump to vacuumize the vacuum chamber, so that the air pressure in the vacuum chamber is less than or equal to 5 × 10^-3Pa；

Step 202, introducing argon into a vacuum chamber, and adjusting the flow of the introduced gas to keep the air pressure of the vacuum chamber at 1-3 Pa;

and 203, providing negative bias voltage of-400 to-1200V, frequency of 20-100 Khz and duty ratio of 50-90% for the alloy cutter through an external power supply, then starting cleaning, and finishing glow cleaning after cleaning for 10-20 min.

In one embodiment of the present invention, in step 202, the pressure in the vacuum chamber is preferably maintained at 1.2 Pa.

In one embodiment of the present invention, in step 203, the parameters provided by the external power supply to the alloy cutting tool are preferably: negative bias voltage-800V, frequency 40Khz and duty ratio 90%.

In one embodiment of the present invention, in step 300, the adjustment parameters of the HiPIMS power supply are preferably: the voltage is-550V to-650V, the frequency is 100hz to 250hz, and the pulse width is 100 mus to 250 mus.

In one embodiment of the present invention, in the step 300, the alloy tool is provided with the following preferred parameters by an external power source: the voltage is-50V to-200V, the frequency is 20Khz to 60Khz, and the duty ratio is 70 percent to 90 percent.

In one embodiment of the present invention, in the step 400, the flow rate value of the nitrogen gas is preferably 8sccm to 20 sccm.

In one embodiment of the present invention, in the step 400, the deposition time is preferably 60 min.

In one embodiment of the invention, the coating hardness of the alloy cutter after coating is 32-42 GPa.

In one embodiment of the invention, the surface roughness of the coating of the alloy cutter after the coating is finished is 0.6-1.5 nm.

The (AlCrTiVZr) N coating prepared by the invention is a single FCC crystal structure and tends to be nanocrystallized, the hardness can reach the super-hard level of 41.8GPa at most, and the surface roughness is reduced to below 2nm, which is far beyond the expectation range of the technicians in the field. In addition, the performance of the (AlCrTiVZr) N coating prepared by HiPIMS is far better than that of the (AlCrTiVZr) N coating prepared by conventional magnetron sputtering and high-entropy alloy nitride coatings of other systems.

Drawings

FIG. 1 is a schematic flow chart of a method for producing a superhard high entropy alloy nitride coating according to one embodiment of the present invention;

FIG. 2 is a hardness curve for an ultra hard (AlCrTiVZr) N coating made in accordance with one embodiment of the present invention;

FIG. 3 is a cross-sectional profile of an ultra-hard (AlCrTiVZr) N coating made in accordance with one embodiment of the present invention;

FIG. 4 is a surface topography of an ultra hard (AlCrTiVZr) N coating prepared in accordance with one embodiment of the present invention;

FIG. 5 is a hardness curve for an ultra hard (AlCrTiVZr) N coating made in example two of the present invention;

FIG. 6 is a cross-sectional profile of an ultra-hard (AlCrTiVZr) N coating made in accordance with a second embodiment of the present invention;

FIG. 7 is a surface topography of an ultra hard (AlCrTiVZr) N coating prepared in accordance with a second embodiment of the present invention.

Detailed Description

In one embodiment of the present invention, a method for making a superhard high entropy alloy nitride coating on an alloy cutting tool is disclosed, wherein the high entropy alloy nitride coating is referred to as an (AlCrTiVZr) N coating, as shown in FIG. 1.

The manufacturing process comprises the following steps:

the carbide tool used herein was a cemented carbide tool (YT15) with a size of 15mm by 5 mm. Wherein, the processes of oil removal, rust removal and cleaning all adopt the conventional treatment mode and are not repeated here.

the glow cleaning (plasma cleaning) process in the present embodiment is as follows:

Wherein, the pressure in the vacuum chamber is preferably kept at 1.2 Pa; the parameters provided for the alloy cutter by the external power supply are preferably as follows: negative bias voltage-800V, frequency 40Khz and duty ratio 90%. The washing time is preferably 10 min.

in this processing step, the adjustment parameters of the HiPIMS power supply are preferably: the voltage is-550V to-650V, the frequency is 100hz to 250hz, and the pulse width is 100 mus to 250 mus; the preferred parameters provided by the external power supply to the alloy cutter are as follows: the voltage is-50V to-200V, the frequency is 20Khz to 60Khz, and the duty ratio is 70 percent to 90 percent.

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

The (AlCrTiVZr) N coating prepared by the embodiment has a single FCC crystal structure and tends to be nano-sized, the hardness can reach the super-hard level of 41.8GPa at most, and the surface roughness is reduced to below 2nm, which is far beyond the expectation range of the technical personnel in the field. In addition, the performance of the (AlCrTiVZr) N coating prepared by HiPIMS is far better than that of the (AlCrTiVZr) N coating prepared by conventional magnetron sputtering and high-entropy alloy nitride coatings of other systems.

The HiPIMS technique used in this embodiment is a novel magnetron sputtering technique that uses high peak power (kw/cm)²) And the low duty ratio (1-5%) can generate a highly ionized plasma film forming environment without large particles, enhance the bombardment effect of high-energy particles on the film, promote the repeated nucleation rate and the migration rate of crystal grains, further inhibit the formation of a columnar crystal structure penetrating through the thickness of the film, and improve the compactness and uniformity of the film, and the hardness, wear resistance and corrosion resistance of the film. In addition, the average HiPIMS power is equivalent to that of the traditional magnetron sputtering power, and the cooling requirement of the sputtering target material cannot be increased due to overheating caused by the use of HiPIMS.

The preparation process of this scheme is illustrated by the following specific examples.

The first embodiment.

1. Selecting a hard alloy cutter (YT15) with the size of 15mm by 5mm as a base body, carrying out oil removal, rust removal and cleaning treatment on the hard alloy cutter, then drying and putting into a vacuum chamber;

2. glow cleaning, namely vacuumizing the vacuum cavity by using a mechanical pump and a molecular pump to ensure that the air pressure in the cavity is less than or equal to 5 × 10^-3When Pa is needed, introducing Ar into the vacuum cavity, adjusting the gas flow to ensure that the air pressure in the cavity is 1.2Pa, loading negative bias to 800V on the substrate, ensuring that the duty ratio is 90 percent and the frequency is 40Khz, and completing etching and cleaning on the substrate by utilizing glow discharge for 10 min;

3. deposition of a transition layer: after the glow cleaning of the substrate is completed, the Ar gas flow is adjusted to enable the air pressure of the cavity to be 0.4Pa, a HiPIMS power supply is started, an AlCrTiVZr target is sputtered by the HiPIMS, and an AlCrTiVZr coating of a transition layer is deposited. Wherein the specific parameters of HiPIMS are as follows: the voltage value is-560V, the pulse frequency is 200hz, and the pulse width is 100 mus. The negative bias voltage has specific parameters of-75V voltage value, 40Khz frequency, 90% duty ratio and 1min deposition time.

4. Forming a high entropy nitride (AlCrTiVZr) N coating: after the transition layer is finished, N is slowly introduced into the cavity₂Forming a high-entropy nitride (AlCrTiVZr) N coating by reactive sputtering deposition with the gas flow of 12 sccm; HiP thereinSpecific IMS parameters: the voltage value is-560V, the pulse frequency is 200hz, and the pulse width is 100 mus; the specific parameters of the negative bias are a voltage value of-75V, a frequency of 40Khz and a duty ratio of 90 percent. The deposition time was 60 min.

5. The nano-hardness of the coating was measured by nanoindentation. As shown in fig. 2, the hardness curve of the coating at any three points is obtained by selecting the hardness values of 100nm-200nm indentation areas and averaging the hardness values, wherein the hardness is 41.8 GPa;

6. and observing the section morphology of the coating by adopting a Scanning Electron Microscope (SEM). As shown in fig. 3, the cross-sectional morphology of the coating is dense and has no penetrating columnar crystal structure;

7. the surface morphology and roughness of the above coatings were measured with an Atomic Force Microscope (AFM) with a test area of 5. mu. m.times.5. mu.m. As shown in fig. 4, the surface roughness was 0.64 nm.

Example II,

The substrate selected in this example is identical to that of the first example, and steps 1 and 2 are also identical to those of the first example, except that:

3. basically the same as step 3 in the first embodiment; the difference lies in that: when the HiPIMS is used for preparing the AlCrTiVZr coating of the transition layer, the specific parameters of the HiPIMS are as follows: the voltage value is-700V, the pulse frequency is 80hz, and the pulse width is 80 mus. The specific parameters of the negative bias are that the voltage value is-150V, the frequency is 40Khz, and the duty ratio is 90 percent.

4. Basically the same as step 4 in the first embodiment; the difference lies in that: when HiPIMS is used for preparing a transition layer (AlCrTiVZr) N coating, the specific parameters of the HiPIMS are as follows: the voltage value is-700V, the pulse frequency is 80hz, and the pulse width is 80 mus. The specific parameters of the negative bias are that the voltage value is-150V, the frequency is 40Khz, and the duty ratio is 90 percent. N is a radical of₂The flow rate is 30 sccm;

5. the nano-hardness of the coating was measured by nanoindentation. As shown in fig. 5, the hardness curve at any three points of the formula is obtained by selecting the hardness values of 100nm-200nm indentation areas and averaging the hardness values, wherein the hardness is 32.1 GPa;

6. and observing the section morphology of the coating by adopting a Scanning Electron Microscope (SEM). As shown in fig. 6, the cross-sectional morphology of the coating is dense and has no penetrating columnar crystal structure;

7. the surface morphology and roughness of the above coatings were measured using an Atomic Force Microscope (AFM) with a test area of 5 μm by 5 μm as shown in fig. 7. The surface roughness was 1.51 nm.

Thus, it should be appreciated by those skilled in the art that while a number of exemplary embodiments of the invention have been illustrated and described in detail herein, many other variations or modifications consistent with the principles of the invention may be directly determined or derived from the disclosure of the present invention without departing from the spirit and scope of the invention. Accordingly, the scope of the invention should be understood and interpreted to cover all such other variations or modifications.

Claims

1. A method for manufacturing a superhard high-entropy alloy nitride coating on an alloy cutter is characterized by comprising the following steps:

2. The method of claim 1,

in the step 200, the glow cleaning process for the alloy cutter is as follows:

3. The method of claim 2,

in step 202, the pressure in the vacuum chamber is preferably maintained at 1.2 Pa.

4. The method of claim 2,

in step 203, the parameters provided for the alloy cutter by the external power supply are preferably: negative bias voltage-800V, frequency 40Khz and duty ratio 90%.

5. The method of claim 1,

in step 300, the parameters for adjusting the HiPIMS power supply are preferably: the voltage is-550V to-650V, the frequency is 100hz to 250hz, and the pulse width is 100 mus to 250 mus.

6. The method of claim 1,

in the step 300, the preferable parameters provided to the alloy cutter by the external power supply are as follows: the voltage is-50V to-200V, the frequency is 20Khz to 60Khz, and the duty ratio is 70 percent to 90 percent.

7. The method of claim 1,

in step 400, the flow rate of nitrogen gas is preferably 8sccm to 20 sccm.

8. The method of claim 1,

in the step 400, the deposition time is preferably 60 min.

9. The method of claim 1,

the coating hardness of the alloy cutter after coating is 32-42 GPa.

10. The method of claim 1,

and the roughness of the coating surface of the alloy cutter after the coating is finished is 0.6-1.5 nm.