A hard and wear-resistant TaN / MoS2 composite coating and a preparation method thereof

Abstract

The present application belongs to the field of coating, and particularly relates to a hard wear-resistant TaN / MoS2 composite coating and a preparation method thereof. The present application uses a Ta target and a MoS2 target as target materials, N2 as a reaction gas, and argon as a sputtering gas, and obtains a TaN / MoS2 composite coating on a substrate by direct current magnetron sputtering of the target materials; a total flow of 40 sccm is adopted, and the nitrogen flow is fixed at 4 sccm, and the argon flow is 36 sccm. The solid solubility of Mo atoms and the MoS2 content are changed by changing the power of the MoS2 target material, the hardness and toughness of the coating are improved by solid solution strengthening effect enhancement and grain boundary strengthening, and meanwhile, the special structure of the good mechanical properties and the strong covalent bond and weak van der Waals bond of MoS2 is combined, so that the tribological performance of the coating is improved.

Description

Technical Field

[0001] This invention belongs to the field of coatings, specifically relating to a hard and wear-resistant TaN / MoS2 composite coating and its preparation method. Background Technology

[0002] With the development of industrial technology and the expansion of application fields, complex working conditions have placed higher demands on thin film materials. Wear-resistant protective thin film materials need to possess both high hardness and toughness. However, in reality, increasing hardness often leads to a decrease in toughness, resulting in brittle fracture of the thin film material. Transition metal nitrides (TMNs) such as TaN have excellent physicochemical properties, but they are still insufficient in terms of toughness and friction properties. Therefore, researchers have made many attempts to improve TaN coatings.

[0003] The paper "García E, Flores-Martínez M, Rivera LP, et al. The Effects of the Addition of Zr on the Mechanical and Tribological Properties of TaN Coating[J]. Journal of Materials Engineering and Performance, 2023: 1-11" demonstrates that adding Zr to TaN thin films improves their wear rate (1.5 × 10⁻⁶). -6 (mm3 / N*m), but the hardness is reduced to only 18GPa.

[0004] The paper "Li H, Li J, Kong J, et al. Achieving high toughness and wear resistance for hard TaN-Ag films actuated by Ag[J]. International Journal of Refractory Metals and Hard Materials, 2023, 111: 106076." describes the addition of sparingly soluble Ag atoms to TaN. At an Ag content of 1.2 at.%, the optimal performance is a hardness of 36.1 GPa and a wear rate of 1.9 × 10⁻⁶. -6 mm3 / N*m. Summary of the Invention

[0005] The purpose of this invention is to provide a hard and wear-resistant TaN / MoS2 coating and its preparation method, which prepares a hard and wear-resistant TaN / MoS2 coating by changing the solid solubility of the dopant element Mo and the content of MoS2.

[0006] The technical solution to achieve the purpose of this invention is: a method for preparing a hard and wear-resistant TaN / MoS2 composite coating, using Ta and MoS2 targets as target materials, N2 as the reaction gas, and argon as the sputtering gas, and obtaining the TaN / MoS2 composite coating on the substrate by DC magnetron sputtering of the target materials.

[0007] Furthermore, the following steps are included:

[0008] Step (1): Substrate pretreatment: Select a monocrystalline 100 silicon wafer and cut it to the required size;

[0009] Step (2): Sputter deposition of a Cr transition layer;

[0010] Step (3): Sputtering a TaN / MoS2 hard wear-resistant coating on the Cr transition layer surface: DC magnetron sputtering was used, with the backplane vacuum level set below 4.0 × 10⁻⁶. -3 The sputtering parameters are as follows: Pa, target-substrate distance is 60±5mm, working gas pressure is 0.4±0.1Pa, argon flow rate is 36±3sccm, N2 flow rate is 4±1sccm, Ta target sputtering power is 150±10W, MoS2 target sputtering power is 20-80W, sputtering temperature is 350±20℃, and sputtering time is 45±5min.

[0011] Furthermore, the specific details of the sputtering deposition of the Cr transition layer in step (2) are as follows:

[0012] Using 99.99% high-purity Cr circular bulk material as the magnetron sputtering target, a completely covered Cr thin film was prepared by pre-sputtering on a silicon substrate using radio frequency magnetron sputtering. Specific process parameters were: backplane vacuum of 4 × 10⁻⁶. -3 Below Pa, the working gas pressure is 0.4±0.1Pa, 99.9% high-purity Ar gas is used as the sputtering gas, the sputtering power is 200±10W, the substrate is heated at 350±10℃, no bias voltage is required, and the sputtering time is controlled at 10±2min.

[0013] A hard, wear-resistant TaN / MoS2 composite coating is prepared using the method described above.

[0014] Furthermore, the thickness of the Cr transition layer is 200-300 nm, and the thickness of the TaN / MoS2 coating is 1.71 μm-2.34 μm.

[0015] The innovative addition of MoS2 from transition metal sulfides in this invention enables the preparation of materials with a hardness as high as 39 GPa and a wear rate as low as 1.4 × 10⁻⁶. -6 mm 3A hard, wear-resistant coating with a thickness of / N*m. This invention achieves optimal MoS2 content by adjusting operating parameters, allowing hard TaN nanocrystals to embed into the MoS2 amorphous matrix, significantly reducing friction. Furthermore, an appropriate amount of Mo atoms dissolve into the TaN, achieving solid solution strengthening. Insufficient MoS2 content fails to achieve solid solution strengthening, while excessive MoS2 content results in an excessive amorphous matrix, which can lead to grain boundary slip during friction and crack propagation.

[0016] Compared with the prior art, the significant advantages of this invention are:

[0017] (1) The TaN / MoS2 composite coating has high hardness, good toughness, low friction coefficient and low wear rate. It is a high-performance environmental barrier coating that can be used in various complex environments.

[0018] (2) The present invention can achieve fine adjustment of the coating structure by adjusting the Mo solid solubility, grain size and MoS2 content of the TaN / MoS2 composite coating, thereby achieving adjustment of mechanical and tribological properties.

[0019] (3) The TaN / MoS2 coating designed in this invention contains an intermediate layer of metallic Cr. Cr and Si have a relatively matched crystal lattice, which improves the bonding strength between the coating and the substrate, making the hard and wear-resistant TaN / MoS2 coating bond with the substrate stronger and effectively improving the service life of the coating.

[0020] (4) The preparation process is relatively simple, has reliable repeatability, and is suitable for industrial and engineering applications. Attached Figure Description

[0021] Figure 1 The cross-sectional SEM microstructure of the TaN / MoS2 thin film prepared according to the present invention is shown in (a) TNMD0 and (b) TNMD60.

[0022] Figure 2 The XRD pattern of the TaN / MoS2 thin film prepared according to the present invention.

[0023] Figure 3 The optical morphology of the wear marks on the TaN / MoS2 thin film prepared according to the present invention is shown in (a1) and (a2) is an enlarged view of the dashed area of ​​(a1); (b1) is the optical morphology of the wear marks on TNMD0 and (b2) is an enlarged view of the dashed area of ​​(b1); (c1) is the optical morphology of the wear marks on TNMD60 and (c2) is an enlarged view of the dashed area of ​​(c1).

[0024] Figure 4Raman spectra of the wear-scratched regions of the TaN / MoS2 thin films prepared for this invention; wherein, (a) is a comparison of the Raman spectra of all samples; (b) and (c) are magnified views of the two dashed regions in (a).

[0025] Figure 5 XPS valence band spectra of TaN / MoS2 thin films prepared according to the present invention; wherein, (a) Ta 4f; (b) N 1s;

[0026] (c)Mo 3d; (d)S2p.

[0027] Figure 6 Mechanical and tribological tests were conducted on the TaN / MoS2 thin films prepared for this invention: toughness indices H / E and H3 / E2 and friction coefficient.

[0028] Figure 7 Laser-etched images of the wear marks on the TaN / MoS2 thin films prepared according to this invention; where (a) TNMD0; (b) TNMD60.

[0029] Figure 8 The images show the SEM microstructure of the indented surfaces of the TaN / MoS2 thin films prepared according to this invention; where (a) TNMD0; (b) TNMD20; (c) TNMD60; and (d) TNMD80. Detailed Implementation

[0030] The present invention will now be described in further detail with reference to the accompanying drawings.

[0031] Cubic B1 NaCl structure δ-TaNx possesses unique properties, such as the highest hardness (30-33 GPa) among TMN binary compounds, a valence electron concentration close to the optimal value for toughness, the highest metallic bonding characteristics, and good stability at high temperatures, theoretically supporting a vacancy density of up to 20%. Therefore, TaN thin films have become a research hotspot in recent years. MoS2, due to its extremely low coefficient of friction (CoF), is widely used as a solid lubricant. Therefore, combining the characteristics of TaN and MoS2, TaN+MoS2 composite coatings have become a novel high-strength, high-toughness, friction-reducing, and high-performance thin film.

[0032] This invention prepares a TaN / MoS2 composite coating by combining multi-target DC and radio frequency magnetron sputtering. By utilizing the DC target power of MoS2, the solid solubility of Mo atoms and the content of MoS2 in the film are changed. The prepared TaN / MoS2 composite coating has the characteristics of both TaN and MoS2, and has high hardness, good toughness and excellent wear resistance, which is beneficial to extending the service life of the coating.

[0033] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0034] Comparative Example

[0035] 1. Prepare the target materials: Select a Ta target with a purity of 99.99% and a copper backing of 60×4mm, a MoS2 target with a purity of 99.95% and a Cr target with a purity of 99.99% and a copper backing of 60×4mm.

[0036] 2. Substrate Preparation: In this example, a polished single-crystal silicon (100) substrate is used for thin film structure analysis, mechanical property testing, and tribological property testing. The specific steps include:

[0037] (1) Cut the 40mm×40mm single crystal silicon into 10mm×40mm sizes.

[0038] (2) Place the Ta target and the MoS2 target in the left and right DC evaporation source positions respectively, place the Cr target in the RF evaporation source position, and place the processed single crystal silicon wafer in the sample stage position.

[0039] 3. Sputter deposition of Cr transition layer:

[0040] (1) Close the vacuum chamber and sample stage valve, turn on the cooling water and vacuum gauge, and start the mechanical pump. The vacuum chamber is in pre-vacuum state. When the gas pressure is lower than 20 Pa, turn on the molecular pump and valve G to perform further vacuuming. The vacuum is evacuated to 4.0 × 10⁻⁶ Pa. -3 Pa.

[0041] (2) After the vacuum is completed, Ar is introduced and the temperature is raised to 350°C. The sample stage valve is opened and rotated continuously. The Ar flow rate is adjusted to 40 sccm, the working pressure is 0.4 Pa, and the Cr target power is 200 W. A Cr transition layer is generated on the substrate surface in 10 min with a thickness of about 200-300 nm.

[0042] 4. Sputtering deposition of TaN / MoS2 composite coating: Turn off the RF target, adjust the Ar flow rate to 36 sccm and the N2 flow rate to 4 sccm, turn on the two DC targets, set the Ta target power to 150W and the MoS2 target power to 0W, and deposit the coating for 45 minutes.

[0043] 5. Turn off the target power and gas supply. After the temperature drops to 170°C, turn off the molecular pump. Then, after the vacuum chamber cools naturally to room temperature, remove the film.

[0044] The coating prepared in this example did not contain MoS2 and served as a control group. Figure 1The image shows the SEM cross-sectional microstructure of the coating. The coating thickness is 1.71 μm, with no obvious orientation, a hardness of 27.5 GPa, an elastic modulus of approximately 410.5 GPa, and an H / E ratio of 0.06686. 3 / E 2 The value is 0.1227, and the sample is denoted as TNMD0.

[0045] Example 1

[0046] 1. Prepare the target materials: Select a Ta target with a purity of 99.99% and a copper backing of 60×4mm, a MoS2 target with a purity of 99.95% and a Cr target with a purity of 99.99% and a copper backing of 60×4mm.

[0047] 2. Substrate Preparation: In this example, a polished single-crystal silicon (100) substrate is used for thin film structure analysis, mechanical property testing, and tribological property testing. The specific steps include:

[0048] (1) Cut the 40mm×40mm single crystal silicon into 10mm×40mm sizes.

[0049] (2) Place the Ta target and the MoS2 target in the left and right DC evaporation source positions respectively, place the Cr target in the RF evaporation source position, and place the processed single crystal silicon wafer in the sample stage position.

[0050] 3. Sputter deposition of Cr transition layer:

[0051] (1) Close the vacuum chamber and sample stage valve, turn on the cooling water and vacuum gauge, and start the mechanical pump. The vacuum chamber is in pre-vacuum state. When the gas pressure is lower than 20 Pa, turn on the molecular pump and valve G to perform further vacuuming. The vacuum is evacuated to 4.0 × 10⁻⁶ Pa. -3 Pa.

[0052] (2) After the vacuum is completed, Ar is introduced and the temperature is raised to 350°C. The sample stage valve is opened and rotated continuously. The Ar flow rate is adjusted to 40 sccm, the working pressure is 0.4 Pa, and the Cr target power is 200 W. A Cr transition layer is generated on the substrate surface in 10 min with a thickness of about 200-300 nm.

[0053] 4. Sputtering deposition of TaN / MoS2 composite coating: Turn off the RF target, adjust the Ar flow rate to 36 sccm and the N2 flow rate to 4 sccm, turn on the two DC targets, set the Ta target power to 150W and the MoS2 target power to 20W, and deposit the coating for 45 minutes.

[0054] 5. Turn off the target power and gas supply. After the temperature drops to 170°C, turn off the molecular pump. Then, after the vacuum chamber cools naturally to room temperature, remove the film.

[0055] The properties of the tested thin film sample were: hardness 39.1 GPa, elastic modulus 377.4 GPa, H / E 0.1036, and H... 3 / E 2 The hardness is 0.4197, indicating that the film in this embodiment has the highest relative hardness. The sample is designated as TNMD20.

[0056] Example 2

[0057] Steps 1, 2, and 3 (1) and (2), as well as step 5, are the same as in Example 1;

[0058] In step 4, keeping other conditions unchanged, the MoS2 target power is adjusted to 40W.

[0059] The properties of the tested thin film sample were as follows: hardness 23.8 GPa, elastic modulus 439.7 GPa, H / E 0.05421, and H... 3 / E 2 The value is 0.07005, and the sample is denoted as TNMD40.

[0060] Example 3

[0061] Steps 1, 2, and 3 (1) and (2), as well as step 5, are the same as in Example 1;

[0062] In step 4, keeping other conditions unchanged, the MoS2 target power is adjusted to 60W.

[0063] The properties of the tested film sample were as follows: hardness 30.1 GPa, elastic modulus 390.8 GPa, H / E 0.07702, and 0.1785. The sample was designated as TNMD60.

[0064] Example 4

[0065] Steps 1, 2, and 3 (1) and (2), as well as step 5, are the same as in Example 1;

[0066] In step 4, keeping other conditions unchanged, the MoS2 target power is adjusted to 80W.

[0067] The properties of the tested thin film sample were as follows: hardness 34.5 GPa, elastic modulus 404.3 GPa, H / E 0.08542, and H... 3 / E 2 The value is 0.2520, and the sample is denoted as TNMD80.

[0068] In summary, this invention improves the film adhesion by employing a Cr metal transition layer and designing a film with varying MoS2 target power from 0 to 80 W. The film surface combines the advantages of lubricating MoS2 and δ-TaNx, forming a composite coating that possesses both hardness and frictional properties, effectively enhancing the mechanical and tribological properties of the film. As shown in the figure, TNMD20 exhibits the highest hardness and the highest H / E and H... 3 / E 2 However, it also has the highest coefficient of friction. TNMD40 has the lowest coefficient of friction, but its mechanical properties are poor. TNMD60 is the sample with the best overall performance, such as... Figure 1 The sample consists of columnar crystals perpendicular to the sample surface. Figure 2 The XRD pattern indicates that the crystal is TaN. x (111) Oriented single crystals have high hardness and toughness as well as low friction coefficient and wear rate. Figure 3 , 4 The optical morphology and Raman spectrum of the TaN / MoS2 thin film wear tracks are shown. The composite coating has a smooth wear surface with minimal wear debris. The Raman spectra of the wear track surface and the unwearable area are the same, indicating a very low degree of tribo-oxidation, approximately 0.13 wt.%. A small amount of wear scars and debris are present on the wear track surface, with TaN as the main component. Figure 5 XPS spectra of Ta 4f, N 1s, Mo 3d, and S 2p thin films. Fitting peaks of Ta 4f7 / 2 and Ta 4f5 / 2 at approximately 22.7 eV and 24.6 eV respectively indicate Ta-N with a B1-NaCl structure δ-TaN. Figure 6 The trend of thin film mechanical properties and friction coefficient with the change of MoS2 target power shows that TNMD60 has the best overall performance. Figure 7 This is a laser morphology image of thin film abrasion marks. The TNMD60 surface has a very low wear rate after friction, with only slight scratches on the surface, indicating excellent friction performance. Figure 8 The TNMD0 indentation showed an annular crack inside, the TNMD20 indentation showed brittle cracks at the edge, the TNMD60 indentation showed no cracks inside or at the edge, and the TNMD80 indentation showed microcracks inside.

Claims

1. A method for preparing a hard, wear-resistant TaN / MoS2 composite coating, characterized in that, Using Ta and MoS2 targets as targets, N2 as the reactive gas, and argon as the sputtering gas, a TaN / MoS2 composite coating is obtained on the substrate by DC magnetron sputtering of the targets; the process includes the following steps: Step (1): Substrate pretreatment: Select a monocrystalline 100 silicon wafer and cut it to the required size; Step (2): Sputter deposition of a Cr transition layer; Step (3): Sputtering a TaN / MoS2 hard wear-resistant coating on the Cr transition layer surface: DC magnetron sputtering was used, with the backplane vacuum set to be less than 4.0 × 10⁻⁶. -3 Pa, target-substrate distance is 60±5mm, working gas pressure is 0.4±0.1Pa, argon flow rate is 36±3sccm, N2 flow rate is 4±1sccm, Ta target sputtering power is 150±10W, MoS2 target sputtering power is 60W, sputtering temperature is 350±20℃, sputtering time is 45±5min. The specific steps of sputtering and depositing the Cr transition layer in step (2) are as follows: Using 99.99% high-purity Cr circular bulk material as the magnetron sputtering target, a completely covered Cr thin film was prepared by pre-sputtering on a silicon substrate using radio frequency magnetron sputtering. Specific process parameters were: backplane vacuum of 4 × 10⁻⁶. -3 Below Pa, the working gas pressure is 0.4±0.1Pa, 99.9% high-purity Ar gas is used as the sputtering gas, the sputtering power is 200±10W, the substrate is heated at 350±10℃, no bias voltage is required, and the sputtering time is controlled at 10±2min.

2. A hard, wear-resistant TaN / MoS2 composite coating, characterized in that, Prepared using the method described in claim 1.

3. The composite coating according to claim 2, characterized in that, The thickness of the Cr transition layer is 200-300 nm, and the thickness of the TaN / MoS2 coating is 1.71 μm-2.34 μm.

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