A multilayer gradient high-entropy alloy / Ag wide-temperature-range in-situ friction-reducing composite coating and its preparation method
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-05-20
- Publication Date
- 2026-08-14
AI Technical Summary
[0006]本发明的目的是为了解决现有高熵合金涂层与基体结合强度不足、摩擦过程中易形成脆性氧化物磨粒导致磨损加剧的问题，而提供一种Cr元素阶梯式递增的原位减摩多层梯度高熵合金/Ag复合镀层及其制备方法
[0022] 1. Gradient structure and high bonding strength: Through the stepwise increase of Cr content (0→5→10→15→20 at.%) and the periodic insertion of Ag layers, the modulus and hardness gradient transition is achieved, the internal stress is reduced by about 40%, and the bonding strength Lc1 >2 N.
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Figure CN122564459A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the fields of materials surface engineering and vacuum coating technology, specifically relating to a method for preparing a high-entropy alloy / Ag composite coating with a multi-layer gradient structure on the surface of a metal or alloy using magnetron sputtering. This composite coating can generate a friction-reducing oxide layer in situ during the friction process, achieving in-situ friction reduction over a wide temperature range. Background Technology
[0002] With the increasing demands of high-end equipment for long service life, high reliability, and wide-temperature-range self-lubricating performance of moving parts, traditional single-component hard coatings (such as TiN and CrN) or simple soft metal lubricating coatings (such as Ag and MoS2) are no longer sufficient to meet the application requirements under complex and harsh working conditions. High-entropy alloys, due to their unique high-entropy effect, lattice distortion effect, and slow diffusion effect, exhibit excellent mechanical properties and thermal stability, making them a research hotspot for novel wear-resistant coatings.
[0003] However, existing high-entropy alloy coatings face two major technical bottlenecks: First, the large difference in modulus and thermal expansion coefficient between a single-component high-entropy coating and the substrate can easily generate internal stress, resulting in insufficient bonding strength or peeling of thick coatings; Second, traditional wear-resistant coatings often generate brittle crystalline oxide particles (such as TiO2 and Cr2O3) during friction. These hard particles act as abrasives, which can exacerbate wear rather than protect the surface.
[0004] In recent years, research has proposed the concept of "reactive friction reduction," which involves the in-situ generation of amorphous-nanocrystalline composite oxides at the friction interface. The nanocrystals are solid solutions rather than brittle compound phases, thus simultaneously achieving high strength and uniform plastic deformation capability. However, a stable and controllable process for preparing gradient structure coatings that can induce this "reactive friction reduction" effect is currently lacking.
[0005] Existing methods for preparing gradient coatings using magnetron sputtering often employ multi-target co-sputtering with continuously varying power to create a continuous gradient, or prefabricate multiple targets with different compositions for alternating sputtering. However, the former struggles to precisely control the clarity and periodic thickness of the multilayer interface, while the latter is costly and has low target utilization. More importantly, current technologies lack a design approach that combines a periodic soft metal layer (Ag) with a gradient high-entropy layer and utilizes this structure to actively induce the formation of amorphous-nanocrystalline solid solution oxides at the tribological interface. Therefore, developing a simple, cost-effective method for preparing gradient composite coatings that can achieve "in-situ friction reduction" remains a pressing technical challenge in this field. Summary of the Invention
[0006] The purpose of this invention is to solve the problems of insufficient bonding strength between existing high-entropy alloy coatings and the substrate, and the easy formation of brittle oxide abrasive particles during friction, which leads to increased wear. The invention provides an in-situ friction-reducing multilayer gradient high-entropy alloy / Ag composite coating with a stepwise increase in Cr element and its preparation method.
[0007] The multilayer gradient high-entropy alloy / Ag wide-temperature-range in-situ friction-reducing composite coating of the present invention is deposited on the substrate surface using a multi-target alternating / co-sputtering process with at least one layer of gradient high-entropy alloy / Ag composite coating. The gradient high-entropy alloy / Ag composite coating includes 5 sub-period layers, each sub-period layer consisting of a high-entropy alloy layer and an Ag layer stacked together. The first sub-period layer consists of a TiNbTaZr high-entropy alloy layer and an Ag layer, and the remaining sub-period layers consist of a TiNbTaZrCr high-entropy alloy layer and an Ag layer. Along the growth direction of the composite coating, the Cr content in the high-entropy alloy layer of the 5 sub-period layers increases in a stepwise manner.
[0008] The method for preparing the multilayer gradient high-entropy alloy / Ag wide-temperature-range in-situ friction-reducing composite coating of the present invention is carried out according to the following steps:
[0009] Step 1: Matrix Pretreatment
[0010] The substrate is ground and polished, and then ultrasonically cleaned to obtain a pretreated substrate;
[0011] Step 2: Install the target and evacuate the vacuum:
[0012] TiNbTaZr alloy target, (pure) Cr target and (pure) Ag target are installed on the target position of the magnetron sputtering equipment, and the vacuum chamber of the magnetron sputtering equipment is evacuated.
[0013] Step 3: Pre-sputtering cleaning of the target surface:
[0014] Ar gas is introduced into the vacuum chamber of the magnetron sputtering equipment, the working pressure is adjusted to 0.2~0.8 Pa, the sputtering power supply is turned on, and pre-sputtering treatment is performed at a power of 100~150 W.
[0015] Step 4: Ion etching and cleaning of the substrate surface:
[0016] Ar gas is introduced to a working pressure of 1~5 Pa, and a pulse bias voltage of -400~-800 V is applied to heat the substrate to 300~500℃. Ar⁺ ions are used to perform ion etching and cleaning on the substrate to obtain the ion-etched and cleaned substrate.
[0017] Step 5: Deposit gradient high-entropy alloy / Ag composite coating:
[0018] A multi-target alternating / co-sputtering process is used to deposit at least one gradient high-entropy alloy / Ag composite coating on the surface of a substrate after ion etching and cleaning. The gradient high-entropy alloy / Ag composite coating includes 5 sub-cycle layers, each of which consists of a high-entropy alloy layer and an Ag layer (stacked). The first sub-cycle layer consists of a TiNbTaZr high-entropy alloy layer and an Ag layer, and the remaining sub-cycle layers consist of a TiNbTaZrCr high-entropy alloy layer and an Ag layer. Along the growth direction of the composite coating, the Cr content in the high-entropy alloy layer in the 5 sub-cycle layers increases in a stepwise manner, thus obtaining a gradient high-entropy alloy / Ag composite coating on the substrate.
[0019] Step Six: Vacuum Cooling
[0020] After deposition, the sputtering power supply is turned off, and the furnace is cooled to room temperature to complete the preparation of a multilayer gradient high-entropy alloy / Ag wide-temperature-range in-situ friction-reducing composite coating.
[0021] The multilayer gradient high-entropy alloy / Ag wide-temperature-range in-situ friction-reducing composite coating and its preparation method of the present invention have the following beneficial effects:
[0022] 1. Gradient structure and high bonding strength: Through the stepwise increase of Cr content (0→5→10→15→20 at.%) and the periodic insertion of Ag layers, the modulus and hardness gradient transition is achieved, the internal stress is reduced by about 40%, and the bonding strength Lc1 >2 N.
[0023] 2. Wide temperature range in-situ friction reduction: Friction induces the generation of amorphous-nanocrystalline solid solution oxides (nanocrystalline is an FCC solid solution with no brittle oxide phase), which, combined with Ag diffusion lubrication, achieves a friction coefficient of 0.30~0.40 from room temperature to 400℃, reducing the wear rate by one order of magnitude.
[0024] 3. Process controllability and universality: It adopts three-target co-sputtering + single sputtering alternation (TiNbTaZr alloy target, Cr target, Ag target), and the composition gradient can be directly controlled by the power ratio. The deposition temperature is low (100℃), and the cycle thickness can be linearly adjusted (100~500nm / cycle). It is suitable for various substrates such as titanium alloy and aluminum alloy, and is suitable for industrial production. Attached Figure Description
[0025] Figure 1 This is a schematic diagram of the structure of the multilayer gradient high-entropy alloy / Ag wide-temperature-range in-situ friction-reducing composite coating of the present invention;
[0026] Figure 2 XRD pattern of the multilayer gradient high-entropy alloy / Ag wide-temperature-range in-situ friction-reducing composite coating prepared in Example 1;
[0027] Figure 3The image shows an EDX line scan along the depth direction of the multilayer gradient high-entropy alloy / Ag wide-temperature-range in-situ friction-reducing composite coating prepared in Example 1, to show the periodic distribution of Ag. Detailed Implementation
[0028] Specific Implementation Method 1: The preparation method of the multilayer gradient high-entropy alloy / Ag wide-temperature-range in-situ friction-reducing composite coating in this implementation method is carried out according to the following steps:
[0029] Step 1: Matrix Pretreatment
[0030] The substrate is ground and polished, and then ultrasonically cleaned to obtain a pretreated substrate;
[0031] Step 2: Install the target and evacuate the vacuum:
[0032] TiNbTaZr alloy target, (pure) Cr target and (pure) Ag target are installed on the target position of the magnetron sputtering equipment, and the vacuum chamber of the magnetron sputtering equipment is evacuated.
[0033] Step 3: Pre-sputtering cleaning of the target surface:
[0034] Ar gas is introduced into the vacuum chamber of the magnetron sputtering equipment, the working pressure is adjusted to 0.2~0.8 Pa, the sputtering power supply is turned on, and pre-sputtering treatment is performed at a power of 100~150 W.
[0035] Step 4: Ion etching and cleaning of the substrate surface:
[0036] Ar gas is introduced to a working pressure of 1~5 Pa, and a pulse bias voltage of -400~-800 V is applied to heat the substrate to 300~500℃. Ar⁺ ions are used to perform ion etching and cleaning on the substrate to obtain the ion-etched and cleaned substrate.
[0037] Step 5: Deposit a multilayer gradient high-entropy alloy / Ag composite coating:
[0038] A multi-target alternating / co-sputtering process is used to deposit at least one gradient high-entropy alloy / Ag composite coating on the surface of a substrate after ion etching and cleaning. The gradient high-entropy alloy / Ag composite coating includes 5 sub-period layers, each of which consists of alternating high-entropy alloy layers and Ag layers. The first sub-period layer consists of TiNbTaZr high-entropy alloy layers and Ag layers, and the remaining sub-period layers consist of TiNbTaZrCr high-entropy alloy layers and Ag layers. Along the growth direction of the composite coating, the Cr content in the high-entropy alloy layers of the 5 sub-period layers increases in a stepwise manner, thus obtaining a gradient high-entropy alloy / Ag composite coating on the substrate.
[0039] Step Six: Vacuum Cooling
[0040] After deposition, the sputtering power supply is turned off, and the furnace is cooled to room temperature to complete the preparation of a multilayer gradient high-entropy alloy / Ag wide-temperature-range in-situ friction-reducing composite coating.
[0041] In step two of this embodiment, the TiNbTaZr alloy target is in equimolar ratio and has a purity of 99.95%; the pure Cr target has a purity of 99.9%; the pure Ag target has a purity of 99.9%; the target diameter is 60~120 mm and the thickness is 3~6 mm; the distance between the target and the substrate is 5 cm.
[0042] In step five of this embodiment, the first sub-cycle layer is deposited as follows: the Cr target and Ag target are turned off, and only the TiNbTaZr alloy target is turned on. The sputtering power is set to 150~300 W, and the deposition time is 5~20 minutes to deposit the first high-entropy alloy layer (Cr content 0%). Then the TiNbTaZr target and Cr target are turned off, and only the Ag target is turned on. The sputtering power is set to 50~150 W, and the deposition time is 3~10 minutes.
[0043] Depositing the second sub-cycle layer: Simultaneously turn on the TiNbTaZr target and the Cr target, adjust the power of the TiNbTaZr target to 150~250W, the power of the Cr target to 15~50W, and the deposition time to 5~20 minutes to deposit the second high-entropy alloy layer (Cr content 5%); then turn on only the Ag target.
[0044] Depositing the third sub-period layer: Simultaneously turn on the TiNbTaZr target and the Cr target, adjust the power of the TiNbTaZr target to 130~230W, the power of the Cr target to 30~70W, and the deposition time to 5~20 minutes to deposit the third high-entropy alloy layer (Cr content 10%); then turn on only the Ag target.
[0045] Depositing the fourth sub-cycle layer: Simultaneously turn on the TiNbTaZr target and the Cr target, adjust the power of the TiNbTaZr target to 120~200W, the power of the Cr target to 50~90W, and the deposition time to 5~20 minutes to deposit the fourth high-entropy alloy layer (Cr content 15%); then turn on only the Ag target.
[0046] Depositing the fifth sub-cycle layer: Simultaneously turn on the TiNbTaZr target and the Cr target, adjust the power of the TiNbTaZr target to 100~180W, the power of the Cr target to 70~120W, and the deposition time to 5~20 minutes to deposit the fifth high-entropy alloy layer (Cr content 20%); then turn on only the Ag target.
[0047] Specific Implementation Method Two: This implementation method differs from Specific Implementation Method One in that the material of the substrate described in step one is a single metal or alloy.
[0048] The substrate material in this embodiment is preferably titanium alloy, aluminum alloy, stainless steel, or nickel-based high-temperature alloy.
[0049] Specific Implementation Method Three: This implementation method differs from Specific Implementation Method One or Two in that, in step two, the vacuum chamber of the magnetron sputtering equipment is evacuated to a background vacuum level better than 5 × 10⁻⁶. -3 Pa.
[0050] Specific Implementation Method Four: This implementation method differs from Specific Implementation Methods One to Three in that the pre-sputtering treatment time in step three is 5 to 15 minutes.
[0051] Specific Implementation Method 5: This implementation method differs from Specific Implementation Methods 1 to 4 in that the ion etching cleaning time in step 4 is 10 to 30 minutes.
[0052] Specific Implementation Method Six: This implementation method differs from one of Specific Implementation Methods One to Five in that the multi-target alternating / co-sputtering process described in step five is carried out under an Ar atmosphere, with the working gas pressure controlled at 0.2~0.8 Pa and the deposition temperature at 80~200℃.
[0053] Specific Implementation Method Seven: This implementation method differs from Specific Implementation Methods One to Six in that the thickness of the Ag layer in each sub-period layer in step five is 5~12 nm.
[0054] In this embodiment, the thickness of the Ag layer is preferably 8~10 nm. When the Ag layer thickness is less than 5 nm, the lubrication effect is not obvious. When the Ag layer thickness is greater than 15 nm, the overall hardness of the coating decreases by more than 20%, and the Ag layer is prone to forming penetrating columnar crystals during the deposition process, which reduces the wear resistance.
[0055] Specific Implementation Method Eight: This implementation method differs from Specific Implementation Method Seven in that the thickness of the gradient high-entropy alloy / Ag composite coating in step five is 120~400 nm.
[0056] In this embodiment, the deposition rate is 2.0 ± 0.2 nm / min on a TiNbTaZr target at 200 W, approximately 1.0 ± 0.1 nm / min on a Cr target at 80 W, and approximately 1.5 ± 0.2 nm / min on an Ag target at 80 W. By controlling the deposition time of each layer within the range of 6 to 15 minutes, a coating with a total thickness of 120 to 400 nm can be obtained in a single cycle.
[0057] Specific Implementation Method Nine: This implementation method differs from Specific Implementation Methods One to Eight in that the atomic percentage of Cr in the high-entropy alloy layer of the five sub-period layers in step five is 0%, 4.0%~5.5%, 9.0%~11.5%, 14.0%~15.5%, and 19.0%~20.5%, respectively.
[0058] Specific Implementation Method 10: This implementation method differs from Specific Implementation Methods 1 to 8 in that it repeats step 5 1 to 3 times.
[0059] This embodiment repeats the process of step five to prepare a multilayer gradient high-entropy alloy / Ag composite coating.
[0060] Example 1: The preparation method of the multilayer gradient high-entropy alloy / Ag wide-temperature-range in-situ friction-reducing composite coating in this example is carried out according to the following steps:
[0061] Step 1: Matrix Pretreatment
[0062] TC4L titanium alloy was used as the substrate material, with a diameter of 25 mm and a thickness of 6 mm. The substrate surface was polished sequentially using 200#, 600#, 1000#, 2000#, and 3000# wet sandpaper to obtain a smooth surface. The polished substrate was ultrasonically cleaned in acetone for 15 minutes, then ultrasonically cleaned in anhydrous ethanol for 15 minutes, and finally dried in an 80℃ oven to obtain the pretreated substrate.
[0063] Step 2: Install the target and evacuate the vacuum:
[0064] Equimolar ratio TiNbTaZr alloy targets (99.95% purity), Cr targets (99.9% purity), and Ag targets (99.9% purity) were mounted on the target positions of the magnetron sputtering equipment. The target diameter was 101.6 mm and the thickness was 4.5 mm. The distance between the target and the substrate was 5 cm. The vacuum chamber of the magnetron sputtering equipment was evacuated to a base vacuum of 8 × 10⁻⁶. -4 Pa;
[0065] Step 3: Pre-sputtering cleaning of the target surface:
[0066] Ar gas was introduced into the vacuum chamber of the magnetron sputtering equipment at a flow rate of 80 sccm. The working pressure was adjusted to 0.5 Pa. The sputtering power supply was turned on, and pre-sputtering was performed at 100 W for 10 minutes.
[0067] Step 4: Ion etching and cleaning of the substrate surface:
[0068] Ar gas was introduced until the working pressure was 3 Pa. A pulse bias voltage of -600 V was applied to heat the substrate to 400°C. The substrate was then ion-etched and cleaned using Ar⁺ ions for 15 minutes to obtain the ion-etched and cleaned substrate.
[0069] Step 5: Deposit a multilayer gradient high-entropy alloy / Ag composite coating:
[0070] A multi-target alternating / co-sputtering process was used to deposit a multi-layer gradient high-entropy alloy / Ag composite coating on the substrate surface after ion etching and cleaning. The deposition conditions were: Ar atmosphere, working pressure of 0.3 Pa, deposition temperature of 100℃, and Ar gas flow rate of 80 sccm.
[0071] The multilayer gradient high-entropy alloy / Ag composite coating consists of 5 sub-period layers, each composed of a high-entropy alloy layer and an Ag layer. The first sub-period layer is composed of a TiNbTaZr high-entropy alloy layer and an Ag layer, while the remaining sub-period layers are composed of a TiNbTaZrCr high-entropy alloy layer and an Ag layer. Along the growth direction of the composite coating, the Cr content in the high-entropy alloy layer of the 5 sub-period layers increases in a stepwise manner, and a multilayer gradient high-entropy alloy / Ag composite coating with a total thickness of about 200 nm is deposited on the substrate.
[0072] The specific deposition conditions for each sub-period layer in this embodiment are as follows:
[0073] ① Deposition of the first high-entropy alloy layer (TiNbTaZr, Cr content 0%): Only the TiNbTaZr alloy target is turned on, sputtering power is 200 W, and deposition time is 10 minutes;
[0074] ② Deposition of the first Ag layer: Turn off the TiNbTaZr target and the Cr target, turn on only the Ag target, sputtering power 80 W, deposition time 6 minutes;
[0075] ③ Deposition of the second high-entropy alloy layer (TiNbTaZrCr~5%): Simultaneously turn on the TiNbTaZr target and the Cr target, with a TiNbTaZr target power of 200 W and a Cr target power of 30 W, and a deposition time of 10 minutes.
[0076] ④ Deposition of the second Ag layer: Only the Ag target is turned on, sputtering power is 80 W, and deposition time is 6 minutes;
[0077] ⑤ Deposition of the third high-entropy alloy layer (TiNbTaZrCr~10%): Simultaneously turn on the TiNbTaZr target and the Cr target, with a TiNbTaZr target power of 180 W and a Cr target power of 50 W, and a deposition time of 10 minutes.
[0078] ⑥ Deposition of the third Ag layer: Ag target only, sputtering power 80 W, deposition time 6 minutes;
[0079] ⑦ Deposition of the fourth high-entropy alloy layer (TiNbTaZrCr~15%): Simultaneously turn on the TiNbTaZr target and the Cr target, with a TiNbTaZr target power of 170 W and a Cr target power of 70 W, and a deposition time of 10 minutes.
[0080] ⑧ Deposition of the fourth Ag layer: Ag target only, sputtering power 80 W, deposition time 6 minutes;
[0081] ⑨ Deposition of the fifth high-entropy alloy layer (TiNbTaZrCr~20%): Simultaneously turn on the TiNbTaZr target and the Cr target, with a TiNbTaZr target power of 150 W and a Cr target power of 80 W, and a deposition time of 10 minutes;
[0082] ⑩ Deposition of the fifth Ag layer: Ag target only, sputtering power 80 W, deposition time 6 minutes.
[0083] Step Six: Vacuum Cooling
[0084] After deposition, turn off all sputtering power supplies and maintain the background vacuum level of the vacuum chamber at 8 × 10⁻⁶. -4 Pa allows the coated substrate to cool naturally to room temperature in the furnace, resulting in a multi-layer gradient high-entropy alloy / Ag wide-temperature-range in-situ friction-reducing composite coating.
[0085] The effects of the multilayer gradient high-entropy alloy / Ag wide-temperature-range in-situ friction-reducing composite coating technology prepared in this embodiment are as follows:
[0086] (1) Structural characterization: The interface structure and composition distribution of the coating were analyzed using scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). Figure 2 As shown. The wide-temperature-range in-situ friction-reducing composite coating prepared in this embodiment is tightly bonded without obvious delamination, and the cross-section shows a columnar crystal structure distribution. TiNbTaZrCr and Ag elements are periodically distributed. Moreover, the coatings all exhibit typical face-centered cubic (FCC) crystal structure characteristics, and their diffraction peaks correspond to the (111), (200), (220) and (311) crystal plane families, respectively. This indicates that the Ag layer maintains a stable FCC phase in the multilayer system.
[0087] (2) Mechanical properties: The total thickness of the coating is approximately 200 nm, and the nanoindentation hardness is 2.2 ± 0.3 GPa. The bonding strength was tested using the scratch method (e.g., Figure 3 As shown in the figure, the critical load Lc1 for the scratch test is > 2.3N, indicating good coating adhesion.
[0088] (3) Tribological properties and verification of the "in-situ friction reduction" mechanism:
[0089] Ball-disc tribological wear tests were conducted over a wide temperature range of room temperature to 400℃ (using SiC for the grinding pair, with a load of 5 N and a linear velocity of 0.1 m / s). The results showed that the coefficient of friction was 0.32–0.33 at room temperature and 0.37–0.39 at 400℃; the wear rate was approximately 1 / 10 that of the TC4L matrix.
[0090] The wear tracks of the TiNbTaZr / Ag multilayers are smooth with a small amount of wear debris, indicating abrasive wear. No coating splitting, peeling, or flaking was observed on the wear tracks. The TiNbTaZr-doped Cr / Ag multilayers exhibit good coating adhesion due to the addition of Cr, and the wear mechanism is adhesive wear. Elemental analysis revealed the formation of friction-reducing and wear-resistant oxides.
Claims
1. A multilayer gradient high-entropy alloy / Ag wide-temperature-range in-situ friction-reducing composite coating, characterized in that... The multilayer gradient high-entropy alloy / Ag wide-temperature-range in-situ friction-reducing composite coating is deposited on the substrate surface using a multi-target alternating / co-sputtering process, with at least one layer of gradient high-entropy alloy / Ag composite coating. The gradient high-entropy alloy / Ag composite coating includes 5 sub-cycle layers, each of which consists of a stack of high-entropy alloy layers and Ag layers. The first sub-cycle layer consists of a TiNbTaZr high-entropy alloy layer and an Ag layer, while the remaining sub-cycle layers consist of a TiNbTaZrCr high-entropy alloy layer and an Ag layer. Along the growth direction of the composite coating, the Cr content in the high-entropy alloy layer of the 5 sub-cycle layers increases in a stepwise manner.
2. The method for preparing the multilayer gradient high-entropy alloy / Ag wide-temperature-range in-situ friction-reducing composite coating as described in claim 1, characterized in that... The preparation method of a multilayer gradient high-entropy alloy / Ag wide-temperature-range in-situ friction-reducing composite coating is carried out according to the following steps: Step 1: Matrix Pretreatment The substrate is ground and polished, and then ultrasonically cleaned to obtain a pretreated substrate; Step 2: Install the target and evacuate the vacuum: TiNbTaZr alloy target, Cr target and Ag target are installed on the target position of the magnetron sputtering equipment, and the vacuum chamber of the magnetron sputtering equipment is evacuated. Step 3: Pre-sputtering cleaning of the target surface: Ar gas is introduced into the vacuum chamber of the magnetron sputtering equipment, the working pressure is adjusted to 0.2~0.8 Pa, the sputtering power supply is turned on, and pre-sputtering treatment is performed at a power of 100~150 W. Step 4: Ion etching and cleaning of the substrate surface: Ar gas is introduced to a working pressure of 1~5 Pa, and a pulse bias voltage of -400~-800 V is applied to heat the substrate to 300~500℃. Ar⁺ ions are used to perform ion etching and cleaning on the substrate to obtain the ion-etched and cleaned substrate. Step 5: Deposit a multilayer gradient high-entropy alloy / Ag composite coating: A multi-target alternating / co-sputtering process is used to deposit at least one gradient high-entropy alloy / Ag composite coating on the surface of a substrate after ion etching and cleaning. The gradient high-entropy alloy / Ag composite coating includes 5 sub-period layers, each of which consists of a high-entropy alloy layer and an Ag layer. The first sub-period layer consists of a TiNbTaZr high-entropy alloy layer and an Ag layer, and the remaining sub-period layers consist of a TiNbTaZrCr high-entropy alloy layer and an Ag layer. Along the growth direction of the composite coating, the Cr content in the high-entropy alloy layer in the 5 sub-period layers increases in a stepwise manner, thus obtaining a gradient high-entropy alloy / Ag composite coating on the substrate. Step Six: Vacuum Cooling After deposition, the sputtering power supply is turned off, and the furnace is cooled to room temperature to complete the preparation of a multilayer gradient high-entropy alloy / Ag wide-temperature-range in-situ friction-reducing composite coating.
3. The method for preparing a multilayer gradient high-entropy alloy / Ag wide-temperature-range in-situ friction-reducing composite coating according to claim 2, characterized in that... The substrate material mentioned in step one is a single metal or alloy.
4. The method for preparing a multilayer gradient high-entropy alloy / Ag wide-temperature-range in-situ friction-reducing composite coating according to claim 2, characterized in that... The pre-sputtering treatment time in step three is 5 to 15 minutes.
5. The method for preparing a multilayer gradient high-entropy alloy / Ag wide-temperature-range in-situ friction-reducing composite coating according to claim 2, characterized in that... The ion etching cleaning time in step four is 10-30 minutes.
6. The method for preparing a multilayer gradient high-entropy alloy / Ag wide-temperature-range in-situ friction-reducing composite coating according to claim 2, characterized in that... The multi-target alternating / co-sputtering process described in step five is carried out under an Ar atmosphere, with the working gas pressure controlled at 0.2~0.8 Pa and the deposition temperature at 80~200℃.
7. The method for preparing a multilayer gradient high-entropy alloy / Ag wide-temperature-range in-situ friction-reducing composite coating according to claim 2, characterized in that... In step five, the thickness of the Ag layer in each sub-period layer is 5~12 nm.
8. The method for preparing a multilayer gradient high-entropy alloy / Ag wide-temperature-range in-situ friction-reducing composite coating according to claim 7, characterized in that... In step five, the thickness of the gradient high-entropy alloy / Ag composite coating is 120~400 nm.
9. The method for preparing a multilayer gradient high-entropy alloy / Ag wide-temperature-range in-situ friction-reducing composite coating according to claim 2, characterized in that... In step five, the atomic percentage of Cr in the high-entropy alloy layer of the five sub-period layers is 0%, 4.0%~5.5%, 9.0%~11.5%, 14.0%~15.5%, and 19.0%~20.5%, respectively.
10. The method for preparing a multilayer gradient high-entropy alloy / Ag wide-temperature-range in-situ friction-reducing composite coating according to claim 2, characterized in that... Repeat step five 1 to 3 times.