A dual-phase HfMoNbZr high-entropy carbide film and a preparation method thereof

Abstract

The application discloses a kind of two-phase HfMoNbZr high-entropy carbide film and preparation method thereof, belong to high-entropy carbide film technical field, the film is prepared by using direct current magnetron sputtering technology co-sputtering quaternary alloy target and graphite target, the film prepared is dense and has columnar crystal structure, the atomic percentage content of each element in the film is calculated as follows: Hf 18.34%-21.01%, Mo 16.02%-18.23%, Nb 15.54%-17.52%, Zr 16.23%-17.81%, C 25.43%-33.87%.The application can effectively improve the mechanical properties and wear resistance of high-entropy alloy film by doping carbon element in high-entropy alloy film, the high-entropy carbide film prepared has higher hardness, high elastic modulus and excellent wear resistance, provides a theoretical basis for preparing hard protective layer with more excellent performance and applied to surface engineering field such as cutter and die.

Description

Technical Field

[0001] This invention belongs to the field of high-entropy carbide thin film technology, and relates to a two-phase HfMoNbZr high-entropy carbide thin film, as well as a method for preparing the two-phase HfMoNbZr high-entropy carbide thin film and its applications. Background Technology

[0002] Carbide thin films possess excellent uniformity, protective properties, wear resistance, and long service life, making them promising candidates for surface coatings. In recent years, hard protective coatings composed of binary or ternary carbide thin films have been widely used in aerospace, nuclear reactors, military equipment, cutting tools, and machining. However, with the diversification of processing methods and the increasing complexity of processed materials, traditional carbide thin films face growing pressure in more complex working environments. Therefore, there is an urgent need to develop more high-performance carbide ceramic thin films to cope with various harsh working conditions. High-entropy alloys, due to their rich elemental combinations and simple single-phase structure, offer limitless possibilities for the design of novel materials. Inspired by high-entropy alloys, researchers began studying high-entropy carbide thin films. High-entropy carbide thin films overcome the limitations of the single-component properties of traditional carbide thin films, possessing not only high hardness and elastic modulus, low coefficient of friction and wear rate, but also excellent corrosion resistance. This makes them more suitable than traditional carbide thin films for operating environments with extreme conditions such as high temperature, friction and wear, and corrosion. These unique performance characteristics make it a promising new material, providing a theoretical basis for the preparation of more high-performance hard protective coatings and their application in the field of surface engineering for materials such as cutting tools and molds.

[0003] High-entropy carbide thin films have attracted widespread attention from researchers due to their simple microstructure and excellent mechanical properties. Chinese patent application (publication number CN114574827A) uses magnetron sputtering to prepare VAlTiCrSiC high-entropy carbide thin films, achieving a hardness of 23.6 GPa and good wear resistance. Chinese patent application (publication number CN114196914A) discloses a preparation process for a (ZrCrTiVNb)C high-entropy carbide ceramic coating. The high-entropy carbide ceramic coating prepared by this process exhibits high hardness, outstanding wear resistance, and excellent corrosion resistance, and has been widely used as a hard protective layer on tool surfaces.

[0004] Recent in-depth research on high-entropy carbide thin films has revealed that films with a two-phase structure exhibit better mechanical properties than those with a single-phase solid solution structure. The presence of a two-phase structure can compensate for the shortcomings of single-phase solid solution structures, while also providing higher hardness and elastic modulus. This is attributed to the fact that the two-phase structure hinders dislocation slip movement, resulting in significant solid solution strengthening and precipitation strengthening effects. This provides an effective design approach for improving the strength and service life of cutting tools. Summary of the Invention

[0005] The technical problem to be solved by this invention is to provide a dual-phase HfMoNbZr high-entropy carbide thin film and its preparation method, which has the characteristics of high hardness and low friction coefficient, providing a theoretical basis for future tool protection layers with better performance, and solving the problems in the prior art.

[0006] The technical solution adopted in this invention is as follows: a two-phase HfMoNbZr high-entropy carbide thin film, obtained by co-sputtering deposition using a HfMoNbZr quaternary alloy target and a graphite target as targets, and a silicon wafer and an Al2O3 wafer as substrates, employing magnetron sputtering technology. The atomic percentage content of each element in the thin film is as follows: Hf 18.34%~21.01%, Mo 16.02%~18.23%, Nb 15.54%~17.52%, Zr 16.23%~17.81%, and C 25.43%~33.87%.

[0007] Furthermore, the aforementioned thin film possesses a face-centered cubic (FCC) structure and a simple hexagonal (HCP) structure, and its cross-sectional morphology exhibits a typical columnar crystal structure. The film thickness ranges from 2.9 to 3.1 µm, and its cross-sectional morphology is a dense columnar crystal structure.

[0008] Furthermore, the target atom ratio of the above-mentioned HfMoNbZr quaternary alloy is an equimolar ratio.

[0009] Furthermore, the hardness of the aforementioned film is 24.5~31.7 GPa, the elastic modulus is 238.3~297.1 GPa, and the wear rate is 4.6×10⁻⁶. -15 ~6.9×10 -15 m 3 ·N -1 ·m -1 .

[0010] Furthermore, the purity of the above-mentioned HfMoNbZr quaternary alloy target is >99.99%, and the purity of the graphite target is >99.98%.

[0011] Furthermore, both the silicon wafer and the Al2O3 substrate are polished on one side.

[0012] Furthermore, the aforementioned deposition power source is a DC power source.

[0013] A method for preparing a dual-phase HfMoNbZr high-entropy carbide thin film includes the following steps:

[0014] Step 1: Clean the substrate surfaces of the silicon wafer and Al2O3 wafer, dry them with air after cleaning, and fix them on the sample tray.

[0015] Step 2: Install the sample disk in the chamber of the JCP-500 multi-target magnetron sputtering instrument, close the chamber door and sequentially perform high vacuum evacuation, substrate heating, inert gas introduction, and deposition gas pressure adjustment. Open the substrate baffle and perform thin film deposition. Use HfMoNbZr quaternary alloy target and graphite target as target materials, and silicon wafer and Al2O3 wafer as substrates for co-sputtering deposition using magnetron sputtering technology to obtain a two-phase HfMoNbZr high-entropy carbide thin film, that is, the thin film has a face-centered cubic structure and a simple hexagonal structure, and the cross-sectional morphology shows a dense columnar crystal structure.

[0016] Step 3: After the temperature has cooled down, remove the film sample and store it.

[0017] The specific operation for cleaning the substrate surface in step one is as follows: After rinsing the substrate of the silicon wafer and Al2O3 wafer with deionized water, clean it in a 30 kHz ultrasonic cleaner for 20-30 minutes in sequence with petroleum ether and anhydrous ethanol.

[0018] The conditions for thin film deposition in step two are as follows: the distance between the HfMoNbZr quaternary alloy target and the graphite target and the substrate is 9~11 mm, and the back vacuum is 2×10⁻⁶. -3 Pa, heating temperature ≥500 ℃, deposition time 180 min, sputtering power of quaternary alloy target controlled at 150 W, sputtering power of graphite target 60~120 W, argon flow rate 40 sccm, argon gas purity ≥99.99%, cooling temperature 80~90 ℃.

[0019] Application of a prepared biphase HfMoNbZr high-entropy carbide thin film in the preparation of protective layers for tool and mold surfaces.

[0020] The beneficial effects of the present invention are as follows: Compared with the prior art, the present invention has the following advantages:

[0021] 1) High-entropy carbide thin films prepared using DC magnetron sputtering technology offer a simple process, allow for effective control of carbon content, and result in dense, uniformly distributed films. Carbon doping effectively improves the performance of high-entropy alloy films. The metal elements selected in this invention are all strong carbide-forming elements, forming strong covalent bonds with carbon atoms, thus enhancing the film's mechanical properties. Furthermore, carbon doping promotes the formation of a lubricating layer during friction and wear, effectively reducing the film's friction coefficient and improving its wear resistance. Therefore, the high-entropy carbide thin films prepared by this invention possess both excellent mechanical properties and outstanding wear resistance. As a hard protective layer, they can effectively improve tool life and provide theoretical guidance for the development of high-entropy carbide thin films with higher performance.

[0022] 2) In high-entropy carbide films with a dual-phase structure, the different crystalline phases exhibit unique mechanical properties, achieving a balance between strength and toughness. Simultaneously, the interaction between the different crystalline phases in the dual-phase structure effectively hinders dislocation movement and slip, resulting in films with not only high hardness but also good wear resistance. Furthermore, due to the slight difference in lattice constants between the different crystalline phases, the lattice mismatch generated at the grain boundaries after the formation of the dual-phase structure releases some internal stress, thereby improving the stability of the film and enhancing its overall mechanical properties.

[0023] 3) The metal elements used in the high-entropy carbide films prepared in this invention are all strong carbide-forming elements, and the measured hardness is higher than that of the VAlTiCrSiC high-entropy carbide films prepared by magnetron sputtering technology in Chinese patent application (publication number CN114574827A), providing a theoretical basis for further preparation of high-entropy carbide films with superior performance. Secondly, in the (ZrCrTiVNb)C high-entropy carbide coating prepared in Chinese patent application (publication number CN114196914A), the carbon source is carbon-containing gas (C2H2). During film deposition, hydrogen is inevitably introduced to form CH bonds, which affects the film's performance. Furthermore, using carbon-containing gas as the carbon source makes it difficult to control the carbon content of the film. In this invention, using a graphite target as the carbon source effectively avoids the influence of hydrogen on the film's performance, and the carbon content in the film is simple and controllable. Attached Figure Description

[0024] Figure 1 The XRD patterns are those of the high-entropy carbide films prepared in Examples 1-4 of this invention.

[0025] Figure 2 The cross-sectional morphology of the high-entropy carbide thin film prepared in Example 1 of the present invention is shown. Detailed Implementation

[0026] The present invention will be further described below with reference to specific embodiments.

[0027] A two-phase HfMoNbZr high-entropy carbide thin film is disclosed, wherein the atomic percentage contents of each element in the film are Hf 18.34%~21.01%, Mo 16.02%~18.23%, Nb 15.54%~17.52%, Zr 16.23%~17.81%, and C 25.43%~33.87%. The high-entropy carbide film exhibits both face-centered cubic (FCC) and simple hexagonal (HCP) structures, and its cross-sectional morphology shows a dense columnar crystal structure. The film thickness is 2.9~3.1 µm, the hardness is 24.5~31.7 GPa, the elastic modulus is 238.3~297.1 GPa, and the wear rate is 4.6×10⁻⁶. -15 ~6.9×10 -15 m 3 ·N -1 ·m -1 .

[0028] The method for preparing this dual-phase HfMoNbZr high-entropy carbide thin film includes the following steps:

[0029] Step 1: Use HfMoNbZr quaternary alloy target and graphite target as sputtering sources, wherein the atomic ratio of HfMoNbZr quaternary alloy target material is close to equimolar ratio;

[0030] Step 2: Remove oil and adhesive from the surface of silicon wafers and aluminum oxide substrates: After rinsing the single-sided polished silicon wafers and Al2O3 wafers with deionized water, clean them in an ultrasonic cleaner at a frequency of 30 kHz for 30 min in sequence with petroleum ether and anhydrous ethanol. After cleaning, dry the substrates with a hair dryer and fix them on the sample tray.

[0031] Step 3: Install the sample tray with the fixed substrate into the chamber and close the substrate baffle. Place the quaternary alloy target and graphite target on the cathode power supply target support stage, with the distance between the target and the substrate controlled at 11 cm and the target surface forming a 45° angle with the substrate surface; close the chamber door and evacuate the back vacuum to 2×10⁻⁶. -3Pa, turn on the substrate heating and control the temperature at 500 ℃, maintain for 10 min to ensure uniform substrate heating; introduce inert gas argon and adjust the deposition gas pressure; adjust the DC magnetron sputtering power supply, set the sputtering power of the quaternary alloy target to 150 W, and the sputtering power of the graphite target to 60 W, 80 W, 100 W, and 120 W respectively, pre-sputter for 5 min before starting deposition to remove contaminants on the target surface; then open the substrate baffle to start depositing the thin film, with the sample disk rotation speed set to 10 r / min and the deposition time set to 180 min; after deposition, turn off the DC power supply and remove the sample after the temperature cools to 85 ℃.

[0032] Examples 1 to 4 below were prepared following the same steps as described above for the preparation of HfMoNbZr high-entropy carbide thin films, with slight differences in process parameters. The microstructure and mechanical properties of the thin films prepared in each example were characterized, including cross-sectional morphology, phase structure, mechanical properties, and tribological coefficient. Specific testing methods are as follows:

[0033] The sputtering power of the target material was controlled using a DC magnetron sputtering power supply (MSD-1A) produced by CNNC Tongchuang; a scanning electron microscope (SEM, Gemini 300, Zeiss) was used to characterize the cross-sectional morphology of the film; an X-ray diffractometer (XRD, D8 Advance, Bruker) was used to analyze the crystal phase structure of the film, with Cu Kα rays of wavelength 0.154056 nm as the test light source, a test angle range of 20°~80°, and a scanning speed of 2° / min; a nanoindenter TTX-NHT3 was used to test the hardness and elastic modulus of the film; and a reciprocating friction and wear testing machine MFT-4000 was used to conduct tribological tests on the film.

[0034] Example 1

[0035] The specific process parameters for preparing HfMoNbZr high-entropy carbide thin films using DC magnetron sputtering in this embodiment are as follows: background vacuum is 2 × 10⁻⁶ m³ / s. -3 The target distance to the substrate surface was 11 mm, the angle between the target surface and the substrate surface was 45°, the deposition temperature was set to 500 ℃, the flow rate of inert gas argon was set to 40 sccm, the deposition pressure of the thin film was 0.45 Pa, the sputtering power of the quaternary alloy target was 150 W, the sputtering power of the graphite target was 120 W, the thin film deposition time was 180 min, and the sample was taken out after cooling to 80 ℃.

[0036] The detection results of this embodiment show that the atomic percentages of each element in the thin film are Hf 18.34%, Mo 16.02%, Nb 15.54%, Zr 16.23%, and C 33.87%; the phase structure of the thin film is as follows: Figure 1 As shown, it exhibits a dual-phase (FCC+HCP) structure; the microstructure of the thin film is as follows. Figure 2 As shown, the film thickness is 3.1 µm, and the cross-sectional morphology exhibits a dense columnar crystalline structure. The film's hardness and elastic modulus were measured to be 31.7 GPa and 297.1 GPa, respectively, with a friction coefficient of 0.39 and a wear rate of 6.9 × 10⁻⁶. -15 m 3 ·N -1 ·m -1 .

[0037] Example 2

[0038] The specific process parameters for preparing HfMoNbZr high-entropy carbide thin films using DC magnetron sputtering in this embodiment are as follows: background vacuum is 2 × 10⁻⁶ m³ / s. -3 The target distance to the substrate surface was 9 mm, the angle between the target surface and the substrate surface was 45°, the deposition temperature was set to 518 ℃, the flow rate of inert gas argon was set to 41 sccm, the deposition pressure of the thin film was 0.48 Pa, the sputtering power of the quaternary alloy target was 151 W, the sputtering power of the graphite target was 80 W, the thin film deposition time was 180 min, and the sample was taken out after cooling to 83 ℃.

[0039] The detection structure of this embodiment shows that the atomic percentages of each element in the film are Hf 19.56%, Mo 17.37%, Nb 16.60%, Zr 17.54%, and C 28.93%; the phase structure of the film is a two-phase (FCC+HCP) structure; the thickness of the film is 3.0 µm, the hardness and elastic modulus are 26.2 GPa and 259.4 GPa, respectively, and the coefficient of friction is 0.47.

[0040] Example 3

[0041] The specific process parameters for preparing HfMoNbZr high-entropy carbide thin films using DC magnetron sputtering in this embodiment are as follows: background vacuum is 2 × 10⁻⁶ m³ / s. -3 The target distance to the substrate surface was 11 mm, the angle between the target surface and the substrate surface was 45°, the deposition temperature was set to 510 °C, the flow rate of inert gas argon was set to 39 sccm, the deposition pressure of the thin film was 0.50 Pa, the sputtering power of the quaternary alloy target was 149 W, the sputtering power of the graphite target was 100 W, the thin film deposition time was 180 min, and the sample was removed after cooling to 85 °C.

[0042] The detection structure of this embodiment shows that the atomic percentages of each element in the film are Hf 18.80%, Mo 16.83%, Nb 15.78%, Zr 16.67%, and C 31.92%; the phase structure of the film is a two-phase (FCC+HCP) structure; the thickness of the film is 2.9 µm, the hardness and elastic modulus are 27.9 GPa and 277.2 GPa, respectively, and the coefficient of friction is 0.45.

[0043] Example 4

[0044] The specific process parameters for preparing HfMoNbZr high-entropy carbide thin films using DC magnetron sputtering in this embodiment are as follows: background vacuum is 2 × 10⁻⁶ m³ / s. -3 The target distance to the substrate surface was 10 mm, the angle between the target surface and the substrate surface was 45°, the deposition temperature was set to 510 ℃, the flow rate of inert gas argon was set to 40 sccm, the deposition pressure of the film was 0.46 Pa, the sputtering power of the quaternary alloy target was 152 W, the sputtering power of the graphite target was 61 W, the film deposition time was 180 min, and the sample was taken out after cooling to 86 ℃.

[0045] The detection structure of this embodiment shows that the atomic percentages of each element in the film are Hf 21.01%, Mo 18.23%, Nb 17.52%, Zr 17.81%, and C 25.43%, respectively; the phase structure of the film is a face-centered cubic single-phase solid solution (FCC); the thickness of the film is 3.1 µm, the hardness and elastic modulus are 24.5 GPa and 238.3 GPa, respectively, and the coefficient of friction is 0.61.

[0046] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of protection of the claims.

Claims

1. A dual-phase HfMoNbZr high-entropy carbide thin film, characterized in that: The thin film was obtained by co-sputtering with a silicon wafer and an Al2O3 substrate using a quaternary alloy target of HfMoNbZr and a graphite target. The atomic percentage contents of each element in the thin film were Hf 18.34%~21.01%, Mo 16.02%~18.23%, Nb 15.54%~17.52%, Zr 16.23%~17.81%, and C 25.43%~33.87%. The thin film has a face-centered cubic (FCC) structure and a simple hexagonal (HCP) structure, and the cross-sectional morphology shows a dense columnar crystal structure.

2. The dual-phase HfMoNbZr high-entropy carbide thin film according to claim 1, characterized in that: The hardness of the film is 24.5-31.7 GPa, the elastic modulus is 238.3-297.1 GPa, the wear rate is 4.6*10 -15 ~6.9*10 -15 m 3 ·N -1 ·m -1 .

3. The dual-phase HfMoNbZr high-entropy carbide thin film according to claim 1, characterized in that: The purity of the HfMoNbZr quaternary alloy target is >99.99%, and the purity of the graphite target is >99.98%.

4. The dual-phase HfMoNbZr high-entropy carbide thin film according to claim 3, characterized in that: Both the silicon wafer and the Al2O3 substrate are polished on one side.

5. The dual-phase HfMoNbZr high-entropy carbide thin film according to claim 1, characterized in that: The co-sputtering deposition was performed using a DC power supply.

6. A method for preparing a dual-phase HfMoNbZr high-entropy carbide thin film as described in any one of claims 1-5, characterized in that, Includes the following steps: Step 1: Clean the substrate surfaces of the silicon wafer and Al2O3 wafer, dry them with air after cleaning, and fix them on the sample tray. Step 2: Install the sample disk in the chamber of the multi-target magnetron sputtering instrument, close the chamber door and sequentially perform high vacuum evacuation, substrate heating, inert gas introduction, and deposition gas pressure adjustment. Open the substrate baffle and perform thin film deposition. Use HfMoNbZr quaternary alloy target and graphite target as target materials, and silicon wafer and Al2O3 wafer as substrates for co-sputtering deposition using magnetron sputtering technology to obtain a two-phase HfMoNbZr high-entropy carbide thin film, that is, the thin film has a face-centered cubic structure and a simple hexagonal structure, and the cross-sectional morphology shows a dense columnar crystal structure. Step 3: After the temperature has cooled down, remove the film sample and store it.

7. The method for preparing a dual-phase HfMoNbZr high-entropy carbide thin film according to claim 6, characterized in that: The specific operation of substrate surface cleaning in step one is as follows: after rinsing the substrate of silicon wafer and Al2O3 wafer with deionized water, it is cleaned in an ultrasonic cleaner with a frequency of 30 kHz for 20~30 min in sequence with petroleum ether and anhydrous ethanol.

8. A method for preparing a dual-phase HfMoNbZr high-entropy carbide thin film according to claim 6 or 7, characterized in that: The conditions for thin film deposition in step two are as follows: the distance between the HfMoNbZr quaternary alloy target and the graphite target and the substrate is 9~11 mm, and the back-side vacuum is 2×10⁻⁶. -3 Pa, heating temperature ≥500 ℃, deposition time 180 min, sputtering power of quaternary alloy target controlled at 150 W, sputtering power of graphite target 60~120 W, argon flow rate 40 sccm, argon gas purity ≥99.99%, cooling temperature 80~90 ℃.

9. The application of the biphase HfMoNbZr high-entropy carbide thin film prepared by the method described in claim 6 or 7 in the preparation of protective layers for tool and mold surfaces.

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