Wear self-monitoring super-hard wear-resistant gradient reinforced coating and preparation method thereof

Abstract

The invention relates to the technical field of tool surface functional coatings, in particular to a wear self-monitoring superhard wear-resistant gradient reinforced coating and a preparation method thereof.The coating comprises a metal substrate, a high-entropy wear-resistant layer, a color layer and a transition layer, and the outer layer is a top high-entropy wear-resistant layer; the high-entropy wear-resistant layer is composed of Ti / Al / Zr / Si / Mo-N, and the hardness gradient of the high-entropy wear-resistant layer is 35-55 GPa; the color layer is of an AlTiN / Si (Ti) double-layer structure and has a multicolor structural color, and the hardness of the color layer is 20-35 GPa; the transition layer is a component gradient system. The preparation method adopts multi-target magnetron sputtering, and comprises the steps of substrate pretreatment, layered deposition (wear-resistant layer / color layer / transition layer), top layer deposition and vacuum cooling. By means of the design, the problems that an existing coating lacks self-monitoring, the hardness gradient is narrow, and interlayer stripping is prone to occurring are solved, abrasion visual monitoring is achieved, super-hard abrasion resistance and high binding force (larger than or equal to 85 N) are achieved, different cutting working conditions are adapted, and the service life of a cutter is greatly prolonged.

Description

Technical Field

[0001] This invention relates to the field of functional coating technology for cutting tool surfaces, specifically to a wear-monitoring superhard wear-resistant gradient enhanced coating and its preparation method. Background Technology

[0002] Cutting tools play a crucial role in the machining of components such as aerospace and precision bearings. The use of cutting tool coatings can significantly extend the service life of cutting tools and improve machining efficiency, and is regarded as a groundbreaking breakthrough in cutting technology.

[0003] Tool coatings have evolved from selecting hard, wear-resistant materials and soft, self-lubricating materials to a stage of nanocomposite and multilayer synergistic structural design. In particular, the recent development of high-entropy structural coatings theoretically allows for the fabrication of tough and wear-resistant tool coatings, making it possible to apply coated tools to efficient and environmentally friendly green cutting processes. However, monitoring the wear of these coatings requires unloading the tool for microscopic morphology inspection, a complex and time-consuming process. Currently, there is almost no research on rapid self-monitoring of wear levels in coated tools. Therefore, there is an urgent need to develop wear-resistant coatings with self-monitoring life. This research can fill the gap in my country's field of wear-resistant and self-monitoring coatings and is of great significance to promoting my country's green cutting manufacturing industry.

[0004] Existing technologies suffer from three major problems: First, high-entropy alloy wear-resistant layers are mostly prepared using composite targets, resulting in poor flexibility in composition control and difficulty in achieving a wide hardness gradient of 35-55 GPa, which cannot adapt to different stress requirements from low-speed to high-speed cutting. Second, color layers are mostly colored only by controlling the thickness, ignoring the influence of the Al:Ti atomic ratio on hardness, resulting in low hardness of the color layer (usually <25 GPa), which is prone to premature wear failure and affects the continuity of monitoring. Third, the abrupt change in elements at the interface between the wear-resistant layer and the color layer results in weak bonding force, making it prone to interlayer delamination under the action of gradient hardness, thus shortening the overall life of the coating.

[0005] Therefore, the market urgently needs a solution that can synergistically optimize coating hardness, wear resistance, and self-monitoring functions to fill the gap in coatings with wide hardness gradients. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention aims to solve the issues of existing tool coatings lacking self-monitoring capabilities and difficulty in achieving synergy between wear resistance and color development, and provides a wear-monitoring, ultra-hard, wear-resistant gradient-enhanced coating and its preparation method.

[0007] The technical solution adopted in this invention is: a method for preparing a wear-self-monitoring superhard wear-resistant gradient-enhanced coating, which employs multi-target magnetron sputtering technology and includes the following steps: S1. Substrate pretreatment: The metal substrate is cleaned and ion bombarded to remove surface oil, impurities and oxide layer. S2, Deposition of high-entropy wear-resistant layer: Prepared by co-sputtering of five high-entropy targets including Ti, Al, Zr, Si and Mo, with nitrogen and argon gas introduced, sputtering deposition on the surface of the metal substrate obtained in step S1; S3, Deposit color layer: Turn off the high-entropy target and turn on the Ti-doped Si(Ti) elemental target. Sputter and deposit the Si(Ti) layer on the surface of the high-entropy wear-resistant layer obtained in step S2. Then turn on the Al / Ti target and introduce nitrogen and argon gas to sputter and deposit the AlTiN layer to form the color layer. S4. Deposit transition layer: Maintain argon flow rate, regulate nitrogen flow rate, keep Al / Ti target on, increase high-entropy target, and adjust the power ratio of Al / Ti target to high-entropy target. Sputter deposit transition layer on the surface of the color layer obtained in step S3. S5. Repeat steps S2-S4 several times to deposit several layers of wear-resistant layer, color layer and transition layer in sequence, with each layer having different deposition parameters. S6. Deposit the top wear-resistant layer: Repeat step S2 again on the outside of the transition layer obtained after step S5 to obtain the top high-entropy wear-resistant layer. S7. Cooling treatment: After deposition, keep the chamber under vacuum and cool to room temperature before removing the sample.

[0008] As a preferred embodiment, the specific steps of substrate pretreatment in step S1 are as follows: the metal substrate is ultrasonically cleaned sequentially with acetone and anhydrous ethanol for 10-15 minutes each; after drying, it is placed in a magnetron sputtering chamber and evacuated to 5×10⁻⁶. -4 Pa, argon gas is introduced and a bias power supply is turned on for ion bombardment etching for 20-25 minutes; the argon gas flow rate is 40-50 SCCM and the bias power supply power is 120W.

[0009] As a preferred embodiment, in step S2, the power ranges of each elemental target in the high-entropy target are as follows: Ti elemental target 80W-180W, Zr elemental target 60W-150W, Mo elemental target 50W-140W, Si elemental target 40W-120W, and Al elemental target 80W-120W, with a deposition pressure of 3.5×10⁻⁶. -1 Pa, deposition temperature 200℃, deposition rate 8-10nm / min, nitrogen flow rate 3SCCM-15SCCM, argon flow rate 45SCCM. In step S3, when depositing the color layer, a Ti-doped Si(Ti) layer is first deposited, followed by an AlTiN layer to form an AlTiN / Si(Ti) bilayer structure. The Si target power for depositing the Si(Ti) layer is 200W, and the Si target contains 0.5-5 at% Ti doping. The thickness of the deposited Si(Ti) layer ranges from 30nm to 100nm. When depositing the AlTiN layer, the nitrogen flow rate is 10SCCM and the argon flow rate is 45SCCM. The Ti elemental target power ranges from 80W to 150W and the Al elemental target power ranges from 220W to 150W in the Al / Ti target. The deposition rate of the AlTiN layer is 7nm / min to 10nm / min, and the thickness of the AlTiN layer ranges from 50nm to 300nm. In step S4, the specific composition of the transition layer is a "Ti-Al-Zr-Si-Mo-N+Al-Ti-N" composite system. During the deposition process, the nitrogen flow rate is 3 SCCM and the argon flow rate is 45 SCCM. The power of each elemental target in the high-entropy target is as follows: Ti elemental target power range is 30W-65W, Al elemental target power range is 40W-75W, Zr elemental target power range is 50W-85W, Si elemental target power range is 30W, Mo elemental target power range is 40W-75W, Al elemental target power range is 30W-100W, and Ti elemental target power range is 20W-90W. The thickness of the transition layer ranges from 50nm to 100nm.

[0010] As a preferred embodiment, in steps S2 to S6, the purity of the high-entropy target and the Al / Ti target is ≥99.9%, the argon gas is ≥99.999%, and the nitrogen gas is ≥99.999%; the hardness of the wear-resistant layer and the color layer gradually increases from the bottom layer to the outer layer, the hardness gradient deviation between adjacent wear-resistant layers is ≤±0.5GPa, and the hardness gradient deviation between adjacent color layers is ≤±0.3GPa.

[0011] As a preferred embodiment, in step S5, during the repeated deposition of the high-entropy alloy wear-resistant layer from the bottom to the top, the Ti target power gradually increases from 80W to 180W, the Zr target power gradually increases from 60W to 150W, the Mo target power gradually increases from 50W to 140W, the Si target power gradually increases from 40W to 120W, and the Al target power gradually decreases from 120W to 80W; the nitrogen flow rate is increased by 2 SCCM each time, with a flow rate range of 3 SCCM to 15 SCCM. During the repeated stacking of the color layers from the bottom to the top, the Al target power is reduced by 10W per layer, and the Ti target power is increased by 10W per layer, so that the Al:Ti ratio in the Al / Ti target gradually changes from 3:1 to 1:1. The Ti doping amount of the Si layer is increased by 0.75at per layer, and the thickness of the AlTiN layer is reduced by 40nm each time. During the repeated stacking process of the transition layer from the bottom to the top, the proportion of high-entropy target power gradually decreases from 90% to 10%, while the proportion of Al / Ti target power gradually increases from 10% to 90%. The transition layer is composed of a "Ti-Al-Zr-Si-Mo-N+Al-Ti-N" composite gradient system. From the wear-resistant layer side to the color layer side, the content of Ti-Al-Zr-Mo elements gradually decreases, the Ti elemental target power gradually decreases (range: 65W-30W), the Al elemental target power gradually decreases (range: 75W-40W), the Zr elemental target power gradually decreases (range: 85W-50W), the Mo elemental target power gradually decreases (range: 75W-40W), the Si target power remains unchanged at 30W, the Al-Ti elemental content gradually increases, the Al elemental target power in the Al / Ti target gradually increases (range: 30W-100W), and the Ti elemental target power gradually increases (range: 20W-90W). The Si elemental content in the transition layer is 5 at.

[0012] A wear-inspection-based ultrahard wear-resistant gradient enhancement coating includes a metal substrate, on which a high-entropy alloy wear-resistant layer, a color layer, a transition layer, and an outermost high-entropy alloy wear-resistant layer are sequentially and alternately deposited. The high-entropy alloy wear-resistant layer is prepared by co-sputtering five metal targets of Ti, Al, Zr, Si, and Mo, and includes the five metal elements and N element, with the hardness gradually increasing from the bottom to the top layer. The color layer is an AlTiN / Si(Ti) bilayer structure, with the Al:Ti atomic ratio and AlTiN layer thickness being different in each layer, exhibiting several structural colors. The transition layer is a composite gradient system of "Ti-Al-Zr-Si-Mo-N (component of the high-entropy wear-resistant layer) + Al-Ti-N (component of the color layer)," with the Ti-Al-Zr-Mo element content gradually decreasing and the Al-Ti element content gradually increasing from the wear-resistant layer side to the color layer side, and the Si element content in each transition layer being 5 at.

[0013] As a preferred embodiment, the atomic percentage of the five metal elements in the high-entropy alloy wear-resistant layer ranges from 5% to 35%, the N element content ranges from 30 at% to 60 at%, the single-layer thickness is 1 μm to 2 μm, and the hardness gradient ranges from 35 GPa to 55 GPa; the Al:Ti atomic ratio of the color layer ranges from (1-3):1, and the AlTiN layer thickness gradually decreases from 300 nm to 50 nm from the bottom layer to the top layer, corresponding to several structural colors such as red, orange, yellow, green, blue, indigo, and violet; the Si layer is prepared by Si elemental target sputtering, and its thickness ranges from 30 nm to 100 nm, and the Ti element content in the Si layer is 0.5 at% to 5 at%; the hardness gradient of the color layer is 20 GPa to 35 GPa.

[0014] As a preferred embodiment, the thickness of the transition layer is 50nm-100nm, and the Si element content is constant at 5at%; from the bottom layer to the top layer, the content of high-entropy alloying elements in the transition layer linearly decreases from 50at% to 5at%, and the high-entropy alloying elements are Ti / Al / Zr / Mo, with the Al / Ti element content linearly increasing from 5at% to 50at%.

[0015] Furthermore, the metal substrate is cemented carbide or high-speed steel, the cemented carbide is WC-Co with a Co content of 6-12wt%, the high-speed steel is W18Cr4V, and the surface roughness Ra of the metal substrate after pretreatment is ≤0.02μm.

[0016] The beneficial effects of this invention are: Firstly, in this invention, the high-entropy alloy wear-resistant layer is co-sputtered using five high-purity elemental targets: Ti, Al, Zr, Si, and Mo. Through a dual approach of "target power control + N content control," a hardness gradient of 35-55 GPa is constructed. During the preparation of the high-entropy alloy wear-resistant layer, the nitrogen flow rate is gradually increased from 3 SCCM (bottom layer, N content 30 at%) to 15 SCCM (top layer, N content 60 at%). N forms strong ionic bonds with metal elements, significantly improving the coating hardness and wear resistance. The friction coefficient of the prepared high-entropy alloy wear-resistant layer decreases from 0.25 (bottom layer) to 0.12 (top layer), adapting to the wear requirements of different cutting conditions.

[0017] Secondly, the color layer in this invention adopts an AlTiN / Si bilayer structure. By synchronously controlling the Al:Ti atomic ratio and AlTiN thickness, "precise color development + increasing hardness" is achieved. The ratio of the bottom color layer is Al:Ti=3:1 (Al220W, Ti80W). The high Al content can enhance the color brightness. As the number of layers increases, the Ti content is gradually increased (to Al:Ti=1:1). The introduction of Ti can improve the density and hardness of AlTiN, increasing the hardness of the color layer from 20GPa to 35GPa. AlTiN thickness control: The thickness is controlled by deposition time: 300nm (red) → 258nm (orange) → 217nm (yellow) → 175nm (green) → 133nm (blue) → 92nm (indigo) → 50nm (purple). Seven clear structural colors are achieved by utilizing thin film interference effect, with color uniformity deviation ≤2%. Si layer doping optimization: The Si layer doping is increased from 0.5at% Ti to 5at% Ti. On the one hand, the hardness of the Si layer is increased (from 15GPa to 28GPa). On the other hand, Ti elements can form elemental bridges with the AlTiN layer, enhancing the overall bonding force of the color layer.

[0018] The color layer is controlled by Al:Ti thickness, which ensures that the seven colors are clearly distinguishable (monitoring error ≤2.3%) and achieves a hardness gradient of 20-35GPa to prevent premature wear of the color layer.

[0019] Thirdly, to solve the interfacial stress problem caused by the difference in hardness between the wear-resistant layer and the color layer, this invention designs a transition layer with gradually changing composition. In the transition layer, the Si element is kept constant at 5 at%, and Si can form stable compounds with Ti and Al, enhancing interfacial compatibility. From the wear-resistant layer side to the color layer side, the high-entropy alloying elements (Ti / Zr / Si / Mo) linearly decrease from 50 at% to 5 at%, and the Al / Ti elements linearly increase from 5 at% to 50 at%, eliminating abrupt element changes. The elemental gradient design of the transition layer makes the interlayer bonding force ≥85N, improves the impact resistance by 65%, and adapts to complex working conditions such as intermittent cutting. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of the structure of the present invention; Figure 2 An optical photograph of the AlTiN / Si(Ti) color layer in this invention; Figure 3 The XRD patterns of the 1st, 3rd, 5th, and 7th (TiAlZrSiMo)N wear-resistant layers in this invention are shown. Figure 4 The hardness of the 1st, 3rd, 5th, and 7th (TiAlZrSiMo)N wear-resistant layers in this invention; Figure 5 The hardness of the 1st, 3rd, 5th, and 7th AlTiN color layers in this invention; Figure 6The figures show the friction and wear morphology of the 1st, 3rd, 5th and 7th (TiAlZrSiMo)N wear-resistant layers in this invention (a, b, c and d in the figure are the 1st, 3rd, 5th and 7th layers). Detailed Implementation

[0022] The present invention will now be described in detail through exemplary embodiments. However, it should be understood that, without further description, elements, structures, and features in one embodiment may be advantageously incorporated into other embodiments.

[0023] It should be noted that, unless otherwise defined, the technical or scientific terms used herein should have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. The terms "a," "an," or "the," and similar words used in the specification and claims of this patent application do not express a limitation of quantity, but rather indicate the presence of at least one; terms such as "comprising" or "including" indicate that the elements or objects preceding "comprising" encompass the elements or objects listed following "comprising" or "including" and their equivalents, but do not exclude other elements or objects having the same function.

[0024] To more clearly describe a wear-monitoring superhard wear-resistant gradient-enhanced coating and its preparation method, combined with the attached... Figure 1 - Appendix Figure 6 This embodiment is described as follows: This embodiment provides a wear-monitoring, ultra-hard, wear-resistant gradient-enhanced coating, which includes a metal substrate and seven layers of high-entropy alloy wear-resistant layer, seven transition layer and seven color layer sequentially deposited on the substrate surface. The outermost layer is a high-entropy alloy wear-resistant layer. The metal substrate is cemented carbide (WC-Co, Co content 6-12wt%) or high-speed steel (W18Cr4V). After pretreatment, the surface roughness Ra≤0.02μm to ensure the initial bonding strength between the coating and the substrate.

[0025] Furthermore, the 7-layer high-entropy alloy wear-resistant layer is prepared by co-sputtering five metal element targets of Ti, Al, Zr, Si and Mo, containing 5 metal elements (atomic percentage of 5-35%) and 30-60 at% N element, with a single layer thickness of 1-2 μm, and a hardness gradient from the bottom layer to the top layer, with a hardness range of 35 GPa→55 GPa. Furthermore, the 7 color layers are AlTiN / Si bilayer structures. The hardness gradient (20GPa→35GPa) is achieved by simultaneously controlling the Al:Ti atomic ratio (3:1→1:1) and the AlTiN layer thickness (300nm→50nm), and they exhibit 7 structural colors: red, orange, yellow, green, blue, indigo and violet. Furthermore, the transition layer has a thickness of 50-100nm and a composition of "Ti-Al-Zr-Si-Mo+Al-Ti" composite gradient system. From the wear-resistant layer side to the color layer side, the content of high-entropy alloying elements (Ti / Zr / Si / Mo) decreases linearly (50at%→5at%), the content of Al / Ti elements increases linearly (5at%→50at%), and the content of Si elements remains constant at 5at% to strengthen the interfacial bonding.

[0026] In this embodiment, the hardness gradient of the high-entropy alloy wear-resistant layer is achieved through the coordinated control of elemental target power and N2 flow rate: from the bottom layer to the top layer, the Ti target power (80W→180W), Zr target power (60W→150W), Mo target power (50W→140W), and Si target power (40W→120W) are gradually increased, while the Al target power (120W→80W) is gradually decreased; at the same time, the N2 flow rate (3SCCM→15SCCM) is increased, so that the N element content increases from 30at% to 60at%, ensuring that the hardness increases linearly from 35GPa to 55GPa.

[0027] In this embodiment, in the AlTiN / Si bilayer structure of the color layer: the AlTiN layer is prepared by co-sputtering of Al and Ti single-element targets, and the Al:Ti atomic ratio is gradually adjusted from 3:1 at the bottom layer (Al target 220W, Ti target 80W) to 1:1 at the top layer (Al target 150W, Ti target 150W); the Si layer is prepared by sputtering of Si single-element targets, with a thickness of 30-100nm, and Ti element is doped from the bottom layer to the top layer (0.5at%→5at%); the thickness of the AlTiN layer gradually decreases from 300nm (red) to 50nm (purple), and the hardness of the corresponding color layer increases from 20GPa to 35GPa, forming a smooth transition with the hardness of the top wear-resistant layer.

[0028] In this embodiment, the transition layer is prepared by co-sputtering of "high-entropy alloy single-element target + Al / Ti single-element target". By adjusting the power ratio of Ti, Al, Zr, Si, Mo targets and Al / Ti targets in real time (wear-resistant layer side: high-entropy target power accounts for 90%, Al / Ti target power accounts for 10%; color layer side: high-entropy target power accounts for 10%, Al / Ti target power accounts for 90%), linear elemental gradient is achieved, the interlayer bonding force is ≥85N, and delamination caused by interface stress concentration is avoided.

[0029] This embodiment uses multi-target magnetron sputtering technology for fabrication, and includes the following steps: I. Coating Preparation and Performance Testing: Substrate selection and pretreatment: WC-Co cemented carbide substrate (Co content 8wt%) was selected, and it was gradually polished to a mirror finish with 1000#-5000# sandpaper. Then, it was ultrasonically cleaned with acetone and anhydrous ethanol for 15 minutes each. After drying, it was placed on the sample stage of the multi-target magnetron sputtering equipment. Ion etching: Close the chamber and start the vacuum pump to evacuate to 5×10⁻⁶. -4 Pa, argon gas was introduced (flow rate: 45 SCCM), the bias power supply (120 W) was turned on, and the substrate was subjected to ion bombardment etching for 25 min. After etching, the surface roughness of the substrate Ra = 0.018 μm. First wear-resistant layer deposition: High-entropy target co-sputtering was initiated, with the following power for each elemental target: Ti target 80W, Al target 120W, Zr target 60W, Si target 40W, and Mo target 50W. Nitrogen (flow rate: 3 SCCM) and argon (flow rate: 45 SCCM) were introduced, and the deposition pressure was 3.5 × 10⁻⁶. -1 Pa, temperature 200℃, deposition for 120 min (thickness 1.0 μm), hardness measured by online nanoindentation instrument was 35 GPa; First color layer deposition: A 40nm Si layer was deposited on a Ti-doped Si target (with a power of 200W and a Ti content of 0.5at%); an Al target with a power of 220W and a Ti target with a power of 80W was set and nitrogen gas (10SCCM) was introduced to deposit a 300nm AlTiN layer, which appeared bright red to the naked eye and had a hardness of 20GPa. First transition layer deposition: The power of the elemental targets was adjusted, with Ti target at 70W, Al target at 100W, Zr target at 50W, Si target at 40W, Mo target at 40W, Al target at 30W, and Ti target at 20W, depositing 80nm. Online glow discharge spectroscopy (GDOES) monitoring was used to ensure a linear gradient of elements from the wear-resistant layer side to the color layer side. GDOES testing showed that Ti element decreased from 18at% to 2at%, and Al element increased from 15at% to 22at%, meeting the gradient requirements. The thickness of the AlTiN layer was precisely controlled by the deposition time, with the deposition rate stable at 7-10nm / min, ensuring that the thickness deviation of different color layers was ≤±5nm, guaranteeing color uniformity and monitoring accuracy. Deposition of layers 2-7: Adjust the parameters as required below: Wear-resistant layer: During each deposition, increase the target power of Ti / Zr / Si / Mo by 15W, 15W, 10W, and 15W respectively, decrease the target power of Al by 5W, increase the N2 flow rate by 2SCCM, and ensure that the hardness increases by 3.3GPa each time, with the hardness of the 7th wear-resistant layer reaching 55GPa. Color layer: During each deposition, the Al target power is reduced by 10W, the Ti target power is increased by 10W (gradually changing the Al:Ti ratio from 3:1 to 1:1), the AlTiN layer thickness is reduced by 40nm (from 300nm to 50nm), the Ti doping amount of the Si layer is increased by 0.75at%, ensuring that the colors are orange, yellow, green, blue, indigo, and violet in sequence, and the hardness increases by 2.5GPa each time, with the hardness of the 7th color layer reaching 35GPa; Transition layer: During each deposition, the proportion of high-entropy target power is reduced by 10%, and the proportion of Al / Ti target power is increased by 10%, maintaining the elemental gradient characteristics; The 7th wear-resistant layer has a hardness of 55 GPa, and the 7th color layer (AlTiN thickness 50 nm, Al:Ti=1:1) is purple with a hardness of 35 GPa.

[0030] Cooling process: After deposition, turn off all power and gas, keep the chamber under vacuum and cool to room temperature (about 2 hours), then open the chamber and take out the sample.

[0031] In this embodiment, the purity of all metal targets is ≥99.9%, and the purity of argon and nitrogen is ≥99.999%, to avoid the influence of impurity elements on coating performance. During the deposition process, the coating hardness is monitored in real time by an online nanoindenter to ensure that the hardness gradient deviation of the wear-resistant layer is ≤±0.5GPa and the hardness gradient deviation of the color layer is ≤±0.3GPa.

[0032] II. Performance Testing: Mechanical properties: wear-resistant layer hardness 35-55GPa, color layer hardness 20-35GPa, friction coefficient 0.12, interlayer bonding force 89N; Optical performance: The CIE color coordinate deviation of the 7-layer color layer is ≤0.02, and the color is uniform and free of impurities; Cutting experiment: Dry cutting of 45# steel (350m / min), the coating wears down to the 3rd layer and exposes yellow. The actual wear amount has an error of 2.1% compared with the theoretical value. The lifespan is 4.5 times that of traditional AlTiN coating.

[0033] Based on the above data, it can be seen that this invention uses five high-purity elemental targets (Ti, Al, Zr, Si, and Mo) for co-sputtering. Through a dual approach of "target power control + N content control," a hardness gradient of 35-55 GPa is constructed, possessing the following technical advantages: 1. Target power optimization: In the bottom wear-resistant layer (hardness 35 GPa), the Al target power is higher (120 W) to improve toughness, while the Ti / Zr / Si / Mo target power is lower (80 / 60 / 40 / 50 W). As the number of layers increases, the Al target power is gradually reduced (to 80 W) to decrease the soft phase, while the Ti / Zr / Si / Mo target power is increased (to 180 / 150 / 120 / 140 W) to increase the presence of strong wear-resistant elements (such as Zr and Mo) and reinforcing phases (nano-Si formations). 1. **Proportion of crystals:** 2. **Nitrogen content control:** Nitrogen flow rate is gradually increased from 3 SCCM (bottom layer, 30 at%) to 15 SCCM (top layer, 60 at%). Nitrogen forms strong ionic bonds with metal elements, significantly improving the coating hardness and wear resistance. 3. **Performance verification:** Through nano-indentation testing, the hardness of the first wear-resistant layer is 35 GPa, the fourth layer is 45 GPa, and the seventh layer is 55 GPa, with a gradient linearity of 98%. The coefficient of friction decreases from 0.25 (bottom layer) to 0.12 (top layer), adapting to the wear requirements of different cutting conditions.

[0034] The color layer of this invention adopts an AlTiN / Si bilayer structure. By synchronously controlling the Al:Ti atomic ratio and the AlTiN thickness, "precise color rendering + increasing hardness" is achieved. The bottom color layer has an Al:Ti ratio of 3:1 (Al 220W, Ti 80W). High Al content enhances color brightness. As the number of layers increases, the Ti content is gradually increased (until Al:Ti = 1:1). The introduction of Ti improves the density and hardness of AlTiN, increasing the hardness of the color layer from 20GPa to 35GPa. The thickness of AlTiN is controlled by deposition time: 300nm (red) → 258nm (orange) → 217nm (yellow) → 175nm (green) → 133nm (blue) → 92nm (indigo) → 50nm (purple). Seven clear structural colors are achieved using thin-film interference effects, with color uniformity deviation ≤2%. Si layer doping optimization: The Si layer doping is increased from 0.5at% Ti to 5at% Ti. On the one hand, this increases the hardness of the Si layer (from 15GPa to 28GPa). On the other hand, Ti can form elemental bridges with the AlTiN layer, enhancing the overall bonding force of the color layer.

[0035] Furthermore, to address the interfacial stress problem caused by the hardness gradient difference between the wear-resistant layer and the color layer, this invention designs a compositionally gradient transition layer. In this transition layer, the Si content is kept constant at 5 at% (Si can form stable compounds with Ti and Al, enhancing interfacial compatibility). From the wear-resistant layer side to the color layer side, the high-entropy alloying elements (Ti / Zr / Si / Mo) linearly decrease from 50 at% to 5 at%, while the Al / Ti content linearly increases from 5 at% to 50 at%, eliminating abrupt elemental changes. The fabrication process employs a "power linear interpolation" method; for example, when depositing the third transition layer, the high-entropy target power accounts for 50%, and the Al / Ti target accounts for 50%, ensuring a smooth transition. The transition layer increases the bonding force between the wear-resistant layer and the color layer from 50N without the transition layer to 90N, and the impact resistance (under a 10N load) increases from 200 cycles to 330 cycles, effectively preventing interlayer delamination.

[0036] It should be noted that although the present invention has been described through the above embodiments, the present invention may have many other embodiments. Without departing from the spirit and scope of the present invention, those skilled in the art can obviously make various corresponding changes and modifications to the present invention, but all such changes and modifications should fall within the scope of protection of the appended claims and their equivalents.

Claims

1. A method of making a wear self-monitoring superhard wear-resistant gradient enhanced coating, characterized in that, The method comprises the following steps: S1, substrate pretreatment: cleaning and ion bombardment etching of the metal substrate to remove surface oil stains, impurities and oxide layers; S2, depositing a high-entropy wear-resistant layer: using single-element target co-sputtering preparation of five high-entropy targets including Ti, Al, Zr, Si and Mo, and sputtering and depositing on the surface of the metal substrate treated in step S1 by introducing nitrogen and argon; S3, depositing a color layer: turning off the high-entropy target and turning on the Si (Ti) single-element target doped with Ti, sputtering and depositing a Si (Ti) layer on the high-entropy wear-resistant layer obtained in step S2, then turning on the Al / Ti target and introducing nitrogen and argon, sputtering and depositing an AlTiN layer to form a color layer; S4, depositing a transition layer: maintaining the argon flow, adjusting the nitrogen flow, keeping the Al / Ti target on, increasing the high-entropy target, and adjusting the power ratio of the Al / Ti target and the high-entropy target, and sputtering and depositing a transition layer on the surface of the color layer obtained in step S3; S5, repeating steps S2-S4 several times to sequentially deposit several layers of wear-resistant layer, color layer and transition layer, wherein the deposition parameters of each layer are different; S6, depositing a top layer of wear-resistant layer: repeating step S2 again on the outside of the transition layer obtained after step S5 to obtain a top layer of high-entropy wear-resistant layer; S7, cooling treatment: after deposition, keeping the chamber in a vacuum state and cooling to room temperature, and taking out the sample.

2. A method of producing a wear self-monitoring superhard wear-resistant gradient enhanced coating according to claim 1, characterized in that, The specific steps of the base pretreatment in step S1 are: the metal base is sequentially cleaned with acetone and anhydrous ethanol for 10-15 minutes by ultrasonic cleaning; after being dried, the base is placed in a magnetron sputtering chamber, vacuumized to 5x10 -4 Pa, argon gas is introduced and a bias power is turned on for ion bombardment etching for 20-25 minutes; the argon gas flow is 40-50 SCCM, and the bias power is 120 W.

3. A method of making a wear self-monitoring superhard wear-resistant gradient enhancement coating according to claim 1, characterized in that, In step S2, the power range of each single element target in the high-entropy target is respectively: Ti single element target 80W-180W, Zr single element target 60W-150W, Mo single element target 50W-140W, Si single element target 40W-120W, Al single element target 80W-120W, and the deposition pressure is 3.5x10 -1 Pa, the deposition temperature is 200℃, the deposition rate is 8-10nm / min, the nitrogen flow rate is 3SCCM-15SCCM, and the argon flow rate is kept at 45SCCM.

4. A method of making a wear self-monitoring superhard wear-resistant gradient enhancement coating according to claim 1, characterized in that, In step S3 of depositing the color layer, the Si (Ti) layer doped with Ti is first deposited, and then the AlTiN layer is deposited to form an AlTiN / Si (Ti) double-layer structure, wherein the Si target power for depositing the Si (Ti) layer is 200 W, the Si target contains 0.5-5 at% Ti doping amount, the deposited Si (Ti) layer has a thickness in the range of 30-100 nm, when depositing the AlTiN layer, the nitrogen flow is 10 SCCM and the argon flow is 45 SCCM, the Ti single-element target power in the Al / Ti target is in the range of 80-150 W, and the Al single-element target power is in the range of 150-220 W; the deposition rate of the AlTiN layer is 7-10 nm / min, and the thickness of the AlTiN layer is in the range of 50-300 nm; In step S4, the specific composition of the transition layer is a "Ti-Al-Zr-Si-Mo-N+Al-Ti-N" composite system, the nitrogen flow is 3 SCCM and the argon flow is 45 SCCM during the deposition process, the power of each single-element target in the high-entropy target is as follows: the Ti single-element target power is in the range of 30-65 W, the Al single-element target power is in the range of 40-75 W, the Zr single-element target power is in the range of 50-85 W, the Si single-element target power is 30 W, and the Mo single-element target power is in the range of 40-75 W, the Al single-element target power in the Al / Ti target is in the range of 30-100 W, and the Ti single-element target power is in the range of 20-90 W, and the thickness of the transition layer is in the range of 50-100 nm.

5. A method of making a wear self-monitoring superhard wear-resistant gradient enhancement coating according to claim 1, characterized in that, The purity of the high-entropy target and the Al / Ti target in steps S2 to S6 is ≥ 99.9%, the purity of argon is ≥ 99.999%, and the purity of nitrogen is ≥ 99.999%; the hardness of the wear-resistant layer and the color layer gradually increases from the bottom layer to the outer layer, the hardness gradient deviation between adjacent wear-resistant layers is ≤ ± 0.5 GPa, and the hardness gradient deviation between adjacent color layers is ≤ ± 0.3 GPa.

6. A method of making a wear self-monitoring superhard wear-resistant gradient enhancement coating according to claim 1, characterized in that, In the process of repeatedly stacking the high-entropy alloy wear-resistant layer from the bottom layer to the top layer in step S5, the Ti target power gradually increases in the range of 80 W to 180 W, the Zr target power gradually increases in the range of 60 W to 150 W, the Mo target power gradually increases in the range of 50 W to 140 W, the Si target power gradually increases in the range of 40 W to 120 W, and the Al target power gradually decreases in the range of 120 W to 80 W; the nitrogen flow rate is increased by 2 SCCM each time, and the flow rate ranges from 3 SCCM to 15 SCCM; In the process of repeatedly stacking the color layer from the bottom layer to the top layer, the Al target power is reduced by 10 W each layer, the Ti target power is increased by 10 W each layer, the Al:Ti ratio in the Al / Ti target is gradually changed from 3:1 to 1:1, the Ti doping amount of the Si layer is increased by 0.75 at% each layer, and the AlTiN layer thickness is reduced by 40 nm each time; In the process of repeatedly stacking the transition layer from the bottom layer to the top layer, the proportion of the high-entropy target power gradually decreases from 90% to 10%, and the proportion of the Al / Ti target power gradually increases from 10% to 90%; the transition layer is composed of a "Ti-Al-Zr-Si-Mo-N+Al-Ti-N" composite gradient system, from the wear-resistant layer side to the color layer side, the Ti-Al-Zr-Mo element content gradually decreases, the Ti elemental target power gradually decreases in the range of 65 W-30 W; the Al elemental target power gradually decreases in the range of 75 W-40 W; the Zr elemental target power gradually decreases in the range of 85 W-50 W; the Mo elemental target power gradually decreases in the range of 75 W-40 W; the Si target power remains unchanged at 30 W; the Al-Ti element content gradually increases, the Al elemental target power in the Al / Ti target gradually increases in the range of 30 W-100 W; the Ti elemental target power gradually increases in the range of 20 W-90 W; and the Si element content in the transition layer is 5 at%.

7. A wear self-monitoring superhard wear-resistant gradient enhanced coating, characterized in that, Prepared according to any one of claims 1 to 6, comprising a metal substrate, a high-entropy alloy wear-resistant layer, a color layer, a transition layer, and a high-entropy alloy wear-resistant layer attached to the outermost layer, which are sequentially and alternately deposited on the surface of the metal substrate; The high-entropy alloy wear-resistant layer is prepared by co-sputtering of Ti, Al, Zr, Si, and Mo metal elemental targets, and the high-entropy alloy wear-resistant layer comprises 5 kinds of metal elements and N elements, and the hardness gradually increases from the bottom layer to the top layer; The color layer is an AlTiN / Si(Ti) double-layer structure, and the Al:Ti atomic ratio and the AlTiN layer thickness of each layer are not the same and exhibit several structural colors. The transition layer composition is a "Ti-Al-Zr-Si-Mo-N+Al-Ti-N" composite gradient system, from the wear-resistant layer side to the color layer side, the Ti-Al-Zr-Mo element content gradually decreases, and the Al-Ti element content gradually increases, and the Si element content in each transition layer is 5at%.

8. A wear self-monitoring superhard wear-resistant gradient enhancement coating according to claim 7, characterised in that, The atomic percentage of the five metal elements in the high-entropy alloy wear-resistant layer ranges from 5% to 35%, the N element content ranges from 30at% to 60at%, the single-layer thickness is 1-2μm, and the hardness gradient ranges from 35GPa to 55GPa; the Al:Ti atomic ratio of the color layer ranges from (1-3):1, the AlTiN layer thickness gradually decreases from 300nm to 50nm from the bottom layer to the top layer, corresponding to red, orange, yellow, green, blue, indigo, purple and other structural colors; the Si layer is prepared by sputtering of a Si single target, with a thickness ranging from 30nm to 100nm, and the Ti element content in the Si layer is 0.5at%-5at%; the hardness gradient of the color layer is 20GPa-35GPa.

9. A wear self-monitoring superhard wear-resistant gradient enhanced coating according to claim 7, characterised in that, The transition layer thickness is 50-100nm, and the Si element content is constant at 5at%; from the bottom layer to the top layer, the high-entropy alloy element content in the transition layer linearly decreases from 50at% to 5at%, and the high-entropy alloy elements are Ti / Al / Zr / Mo, and the Al / Ti element content linearly increases from 5at% to 50at%.

10. A wear self-monitoring superhard wear-resistant gradient enhanced coating according to claim 7, characterised in that, The metal substrate is a hard alloy or a high-speed steel, the hard alloy is WC-Co with a Co content of 6-12wt%, the high-speed steel is W18Cr4V, and the metal substrate is pretreated to have a surface roughness Ra≤0.02μm.

Images