A pvd composite coating and a method for producing the same

Abstract

The application relates to the technical field of metal material coating, in particular to a PVD composite coating and a preparation method thereof; the preparation method comprises the following steps: pretreating a metal base to obtain a pretreated base; using a composite target to perform magnetron sputtering deposition, multiple plasma spraying and laser texturing on the surface of the pretreated base, and repeating the above process to form a composite coating crude product containing a third rare earth doped high-entropy alloy coating; and post-treating the composite coating crude product to obtain a composite coating; wherein the composite target is AlCoCrFeNi-Y, and the composite oxide comprises aluminum oxide, titanium oxide and cerium oxide. The preparation method can significantly improve the bonding strength, hardness and strength of the composite coating by magnetron sputtering deposition of a rare earth doped high-entropy alloy coating, plasma spraying to form a gradient content composite ceramic coating, laser texturing treatment and alternating construction of multiple layers of coatings, and the like, in combination with carefully selected materials with a low expansion coefficient.

Description

Technical Field

[0001] This application relates to the field of metal coating technology, and in particular to a PVD composite coating and its preparation method. Background Technology

[0002] Advanced ceramic materials possess excellent strength and chemical stability, and have been widely used in various wear-resistant and corrosion-resistant applications. Among them, oxide ceramics have been widely used in various fields requiring high hardness. Alumina is the most widely used of these oxide ceramics. However, alumina ceramics currently have two major drawbacks: (1) Ceramic materials are relatively brittle and have low resistance to thermal shock and thermal impact, which makes it difficult for ceramic materials to meet the application requirements of high hardness and high stability environments; (2) When ceramic materials are used as coating raw materials, the bonding strength between the ceramic coating and the substrate material and the density of the coating itself need to be considered. However, in order to ensure the normal function of the coating, the existing alumina ceramic coatings generally have a large particle size, which results in a low bonding strength between the ceramic coating and the substrate material, and the coating structure is relatively loose, making it easy for the ceramic coating to crack.

[0003] Currently, rare-earth-doped high-entropy alloy coatings are widely used in machine tool coatings due to their advantages of high strength, high density, and absence of cracks and shrinkage cavities. Therefore, introducing rare-earth-doped high-entropy alloy coatings into ceramic coatings would undoubtedly effectively improve the hardness and bonding strength of the ceramic coating. However, if rare-earth-doped high-entropy alloy coatings and ceramic coatings are directly laminated, the hardness difference between the two coatings will cause cracks to appear in the ceramic coating during the preparation stage. This would prevent the effective combination of the advantages of both coatings and would instead further exacerbate the deficiencies in the hardness and bonding strength of the ceramic coating. Summary of the Invention

[0004] This application provides a PVD composite coating and its preparation method to solve the following technical problem: how to improve the hardness and bonding strength of rare earth-doped high-entropy alloy coatings and ceramic coatings.

[0005] In a first aspect, this application provides a method for preparing a PVD composite coating, the method comprising:

[0006] The metal substrate is pretreated to obtain a pretreated substrate;

[0007] A first rare-earth-doped high-entropy alloy coating is obtained by magnetron sputtering deposition on the surface of the pretreated substrate using a composite target containing rare earth elements.

[0008] Multiple plasma sprayings were performed on the surface of the first rare earth-doped high-entropy alloy coating using composite oxides to obtain a first composite ceramic coating with gradient content.

[0009] The first composite ceramic coating is laser-textured to form a honeycomb microstructure on the surface of the first composite ceramic coating, thus obtaining a first treatment layer;

[0010] The composite target containing rare earth elements is used to perform magnetron sputtering deposition on the surface of the first processed layer to obtain a second rare earth-doped high-entropy alloy coating.

[0011] The composite oxide is used to perform multiple plasma sprayings on the surface of the second rare earth-doped high-entropy alloy coating to obtain a second composite ceramic coating with gradient content.

[0012] The second composite ceramic coating is subjected to laser texturing to form a honeycomb microstructure on the surface of the second composite ceramic coating, thereby obtaining a second treatment layer;

[0013] The composite target containing rare earth elements is used to perform magnetron sputtering deposition on the surface of the second treatment layer to obtain a crude composite coating containing a third rare earth-doped high-entropy alloy coating.

[0014] The crude composite coating is then post-processed to obtain the composite coating.

[0015] The composite target material is AlCoCrFeNi-Y, and the composite oxide includes aluminum oxide, titanium oxide, and cerium oxide.

[0016] Optionally, the magnetron sputtering deposition pressure is 0.3 Pa to 0.8 Pa, and the magnetron sputtering deposition power density is 2 W / cm³. 2 ~4W / cm 2 The magnetron sputtering deposition voltage is -150V to -50V, the magnetron sputtering deposition temperature is 200℃ to 400℃, and the magnetron sputtering deposition time is 1.5h to 6h.

[0017] Optionally, the power of the plasma spraying is 45kW to 50kW, the voltage of the plasma spraying is 55V to 65V, the powder feeding rate of the plasma spraying is 25g / min to 35g / min, and the spraying distance of the plasma spraying is 80mm to 120mm.

[0018] Optionally, the mass m1 of the alumina, the mass m2 of the titanium oxide, and the mass m3 of the cerium oxide satisfy the relationship m1:m2:m3=(85~75):(5~15):10.

[0019] Optionally, the titanium dioxide content of the first composite ceramic coating is distributed in a gradually increasing manner, with the difference between the mass contents of two adjacent titanium dioxide layers being 2% to 5%; and / or

[0020] The titanium oxide content of the second composite ceramic coating decreases gradually, with the difference between the mass contents of two adjacent titanium oxide layers being 2% to 5%; and / or

[0021] The rare earth element content of the first rare earth-doped high-entropy alloy coating, the second rare earth-doped high-entropy alloy coating, and the third rare earth-doped high-entropy alloy coating is 1.5% to 2.5% by mass.

[0022] Optionally, the thicknesses of the first rare-earth-doped high-entropy alloy coating, the second rare-earth-doped high-entropy alloy coating, and the third rare-earth-doped high-entropy alloy coating are each 5 μm to 10 μm; and / or

[0023] The thickness h1 of the first composite ceramic coating and the thickness h2 of the second composite ceramic coating satisfy the relationship: h1 + h2 = 45 μm ~ 55 μm; and / or

[0024] The pore size of a single honeycomb microstructure in the first and second processing layers is 15 μm to 25 μm, and the depth of a single honeycomb microstructure in the first and second processing layers is 3 μm to 5 μm.

[0025] Optionally, the pulse energy of the laser texturing is 35μJ to 45μJ, the repetition frequency of the laser texturing is 100kHz to 500kHz, the scanning speed of the laser texturing is 100mm / s to 1000mm / s, and the spot diameter of the laser texturing is 15μm to 25μm.

[0026] Optionally, the step of post-processing the crude composite coating to obtain the composite coating includes the following steps:

[0027] The crude composite coating is annealed to obtain an annealed crude composite coating.

[0028] The annealed composite coating rough product is subjected to hot isostatic pressing treatment to obtain the composite coating;

[0029] The annealing temperature is 800℃~900℃, and the annealing time is 1.5h~2.5h.

[0030] The hot isostatic pressing (HIP) treatment is performed at a temperature of 900℃ to 950℃, at a pressure of 100MPa to 150MPa, and for a time of 1h to 2h.

[0031] Optionally, the pretreatment of the metal substrate to obtain a pretreated substrate includes the following steps:

[0032] A rough metal substrate is obtained by sandblasting the metal substrate.

[0033] The rough metal substrate is ultrasonically cleaned to obtain a pretreated substrate.

[0034] Secondly, this application provides a PVD composite coating, which is prepared by the method described in the first aspect; the composite coating covers the surface of a metal substrate, and the composite coating includes multiple rare earth-doped high-entropy alloy coatings and multiple composite ceramic coatings, wherein the composite ceramic coatings and the rare earth-doped high-entropy alloy coatings are arranged alternately, and the rare earth-doped high-entropy alloy coatings are the outermost and innermost layers; the composite ceramic coatings and the rare earth-doped high-entropy alloy coatings are connected and fixed by a processing layer.

[0035] The technical solutions provided in this application have the following advantages compared with the prior art:

[0036] This application provides a method for preparing a PVD composite coating. The method involves first pretreating a metal substrate to remove impurities from its surface. Then, a first rare-earth-doped high-entropy alloy coating is formed on the pretreated substrate surface using a composite target containing rare-earth elements via magnetron sputtering. Next, a first composite ceramic coating with a gradient content is formed on the surface of the first rare-earth-doped high-entropy alloy coating through multiple plasma spraying processes using a composite oxide. Based on the high rare-earth element content of the first rare-earth-doped high-entropy alloy coating, the rare-earth elements can be used to refine the grain size of the metal elements in the coating and optimize the grain boundary distribution, thereby obtaining a dense and high-strength first rare-earth-doped high-entropy alloy coating. Furthermore, these rare earth elements may infiltrate into the first composite ceramic coating during the plasma spraying stage, refining the contact interface between the first composite ceramic coating and the first rare earth-doped high-entropy alloy coating. This results in a strong bond between the two coatings, further enhancing the bonding strength of the composite coating. Additionally, laser texturing can form a honeycomb-like microstructure as a first treatment layer on the surface of the first composite ceramic coating. During subsequent magnetron sputtering deposition, the rare earth-containing composite target can form a uniform and dense second rare earth-doped high-entropy alloy coating on the surface of the first composite ceramic coating, further improving the bonding strength between the two coatings. Subsequent repeated steps such as plasma spraying, laser texturing, and magnetron sputtering deposition can form a second composite ceramic coating and a third rare-earth-doped high-entropy alloy coating on the surface of the second rare-earth-doped high-entropy alloy coating. These uniformly distributed rare-earth-doped high-entropy alloy coatings and composite ceramic coatings can disperse the stress distribution of the composite coating, thereby improving its hardness and strength. Furthermore, setting the composite ceramic coating to a gradient content allows for a uniform distribution of the composite coating's composition and properties, further dispersing the stress distribution and thus improving its hardness and strength. In addition, using AlCoCrFeNi-Y as the composite target and composite oxides including alumina, titanium oxide, and cerium oxide, employing two materials with low coefficients of thermal expansion, can further reduce the thermal stress of the composite coating, thereby improving its hardness and strength. Attached Figure Description

[0037] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0038] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0039] Figure 1 A schematic diagram of a method for preparing a PVD composite coating provided in an embodiment of this application;

[0040] Figure 2 A detailed flowchart illustrating a method for preparing a PVD composite coating, as provided in this application embodiment;

[0041] Figure 3 This is a schematic diagram of the structure of a PVD composite coating provided in Embodiment 1 of this application;

[0042] Figure 4 This is a schematic diagram of the structure of a PVD composite coating provided in Embodiment 4 of this application. Detailed Implementation

[0043] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0044] Various embodiments of this application may exist in the form of a range; it should be understood that the description in the form of a range is merely for convenience and brevity and should not be construed as a hard limitation on the scope of this application; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single numerical values ​​within that range; for example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single numbers within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range; in addition, whenever a numerical range is indicated herein, it means including any referenced number (fraction or integer) within the indicated range.

[0045] In this document, terms such as “comprising” mean “including but not limited to”. Relational terms such as “first” and “second” are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. “And / or” describes the relationship between related objects, indicating that there can be three relationships, for example, A and / or B can mean: A alone, A and B simultaneously, or B alone; where A and B can be singular or plural. “At least one” means one or more, “more” means two or more; “at least one,” “at least one of the following,” or similar expressions refer to any combination of these items, including any combination of single or plural items; for example, “at least one of a, b, or c,” or “at least one of a, b, and c,” can both mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be single or multiple. "Parts representation" such as parts by weight or parts by mass indicates the proportional relationship between components. In the proportional relationships discussed in this article, the parameters that need to be described by proportion should be understood as the first term of the proportion in the order of description, and the proportion figures should be understood as the second term of the proportion. For example, if the mass ratio of substance A, substance B, and substance C is 1:2:3, then substances A, B, and C should correspond one-to-one with the proportion figures in the proportion in the order of description, that is, the mass of substance A: the mass of substance B: the mass of substance C = 1:2:3.

[0046] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this article can be purchased from the market or prepared by existing methods.

[0047] It should be noted that, according to the principles of materials science and tribology, the wear resistance of ceramic materials is not only related to their hardness but also depends more on their toughness. Refining the grain size of ceramic materials can undoubtedly increase both strength and toughness simultaneously, thereby improving their wear resistance. However, simply refining the grain size of ceramic materials is not only costly, but fine-grained ceramic materials are also expensive.

[0048] Therefore, rare earth-doped high-entropy alloy coatings can be introduced. Based on the rare earth elements in the rare earth-doped high-entropy alloy coating, the grain and grain boundary distribution of the ceramic coating can be refined to a certain extent, thereby improving the bonding strength between the rare earth-doped high-entropy alloy coating and the ceramic coating. However, due to the possible differences in the coefficient of thermal expansion between the rare earth-doped high-entropy alloy coating and the ceramic material, as well as the differences in compatibility between the rare earth-doped high-entropy alloy coating and the ceramic coating, these differences make it difficult for the rare earth-doped high-entropy alloy coating and the ceramic coating to fit perfectly. This makes the bonding interface prone to displacement or cracking, which in turn increases the brittleness of the ceramic coating and affects the quality of the final coating.

[0049] Figure 1 An exemplary schematic diagram of a method for preparing a PVD composite coating according to an embodiment of this application is shown;

[0050] like Figure 1 As shown in the embodiment of this application, a method for preparing a PVD composite coating is provided, the method comprising:

[0051] S1. Pre-treat the metal substrate to obtain a pre-treated substrate;

[0052] S2. A first rare earth-doped high-entropy alloy coating is obtained by magnetron sputtering deposition on the surface of the pretreated substrate using a composite target containing rare earth elements.

[0053] S3. Multiple plasma sprayings are performed on the surface of the first rare earth-doped high-entropy alloy coating using composite oxides to obtain a first composite ceramic coating with gradient content.

[0054] S4. The first composite ceramic coating is laser-textured to form a honeycomb microstructure on the surface of the first composite ceramic coating, thereby obtaining a first treatment layer;

[0055] S5. Using the composite target containing rare earth elements, the magnetron sputtering deposition is performed on the surface of the first processed layer to obtain a second rare earth-doped high-entropy alloy coating.

[0056] S6. The composite oxide is used to perform multiple plasma sprayings on the surface of the second rare earth-doped high-entropy alloy coating to obtain a second composite ceramic coating with gradient content.

[0057] S7. The second composite ceramic coating is subjected to laser texturing to form a honeycomb microstructure on the surface of the second composite ceramic coating, thereby obtaining a second processed layer;

[0058] S8. Using the composite target containing rare earth elements, the magnetron sputtering deposition is performed on the surface of the second processed layer to obtain a crude composite coating containing a third rare earth-doped high-entropy alloy coating.

[0059] S9. The crude composite coating is post-processed to obtain the composite coating;

[0060] The composite target material is AlCoCrFeNi-Y, and the composite oxide includes aluminum oxide, titanium oxide, and cerium oxide.

[0061] It should be noted that after laser texturing, dilute hydrochloric acid and hydrofluoric acid can be used for cleaning to remove the oxide layer and molten residue formed on the surface of the composite ceramic layer during the laser texturing stage.

[0062] It should be noted that in many fields of modern industry, the requirements for the surface properties of metallic materials are becoming increasingly stringent. For example, in the aerospace field, components need to operate in extreme environments such as high temperature, high speed, and strong corrosion; in the machinery manufacturing industry, tools and molds need to possess high hardness, high wear resistance, and good fatigue resistance. Physical vapor deposition (PVD) composite coating technology, as a method that can effectively improve the surface properties of metallic materials, is playing an increasingly important role. The PVD composite coating preparation method provided in this application, through a series of unique process steps and carefully selected materials, is expected to significantly improve the overall performance of the composite coating. The specific principle is as follows:

[0063] (1) Metal substrate pretreatment: to lay a solid foundation for coating adhesion.

[0064] During processing, storage, and transportation, metal substrates inevitably become contaminated with various impurities, such as oil, dust, and oxide scale. The presence of these impurities severely affects the adhesion between the subsequent coating and the substrate, leading to easy peeling and reduced protective and reinforcing effects. Therefore, pretreatment of the metal substrate is a crucial initial step in the entire preparation process. The pretreatment process typically involves several steps.

[0065] The first step is degreasing, typically using chemical degreasing, where the metal substrate is immersed in a solution containing a degreasing agent. The degreasing agent reacts chemically with the oil, causing it to detach from the metal surface. Common degreasing agents include alkaline and organic solvent degreasing agents. Alkaline degreasing agents are less expensive and more environmentally friendly, but their effectiveness in removing stubborn oil stains may be limited. Organic solvent degreasing agents have strong degreasing capabilities, but they are volatile and toxic, requiring careful safety precautions during use. After degreasing, the metal substrate still needs rust and scale removal. For lightly rusted metals, acid pickling can be used, immersing the substrate in a dilute acid solution, such as hydrochloric acid or sulfuric acid. The acid reacts chemically with the rust and scale, dissolving and removing them. However, the acid concentration and immersion time must be strictly controlled during acid pickling to avoid excessive corrosion of the metal substrate. For severely rusted metals, mechanical methods such as sandblasting or shot blasting can be used. High-speed abrasive jets impact the metal surface to remove rust and scale, while also increasing surface roughness and improving the bonding area between the coating and the substrate.

[0066] After the above treatment, the impurities on the surface of the metal substrate are completely removed, and the surface becomes clean and has a certain degree of roughness, which provides a good foundation for the subsequent deposition of coatings.

[0067] (2) Magnetron sputtering deposition of first rare earth doped high entropy alloy coating: the strengthening effect of introducing rare earth elements.

[0068] After pretreatment of the metal substrate, a rare-earth-doped high-entropy alloy coating is deposited on the surface of the pretreated substrate using a composite target containing rare-earth elements via magnetron sputtering. Magnetron sputtering is an advanced physical vapor deposition technique. Its working principle involves ionizing inert gases such as argon into plasma in a vacuum environment through the combined action of electric and magnetic fields. Argon ions in the plasma, accelerated by the electric field, bombard the surface of the composite target, sputtering atoms from the target. These atoms then deposit on the substrate surface to form a coating.

[0069] The composite target material used in this application is AlCoCrFeNi-Y, a typical high-entropy alloy target material. It contains multiple main metallic elements such as aluminum (Al), cobalt (Co), chromium (Cr), iron (Fe), and nickel (Ni), and also includes the rare earth element yttrium (Y). High-entropy alloys possess unique crystal structures and excellent properties. The presence of multiple main elements makes the atomic arrangement of the alloy more complex, resulting in a high mixing entropy, which endows the alloy with good strength, hardness, wear resistance, and corrosion resistance.

[0070] The addition of the rare-earth element yttrium further enhances the performance of the high-entropy alloy coating. During coating formation, yttrium plays a role in refining grains and optimizing grain boundary distribution. When metal atoms in the coating are deposited and crystallized on the substrate surface, yttrium preferentially adsorbs at grain boundaries, hindering further grain growth and thus reducing grain size. Grain refinement increases the number of grain boundaries, which, as barriers to atomic movement, effectively impede dislocation movement, improving the coating's strength and hardness. Simultaneously, yttrium lowers the energy of grain boundaries, making them more stable, reducing defect and impurity accumulation at grain boundaries, optimizing grain boundary distribution, and further improving coating performance. Finally, through precise control of the magnetron sputtering deposition process, a dense and high-strength first rare-earth-doped high-entropy alloy coating can be obtained.

[0071] (3) Plasma spraying forms a first composite ceramic coating with gradient content: enhances the coating's adhesion and performance.

[0072] After the first rare-earth-doped high-entropy alloy coating is formed, a first composite ceramic coating with gradient content is formed on its surface by multiple plasma spraying processes using composite oxides. Plasma spraying is a technique that uses high-temperature plasma to heat and melt ceramic powder and spray it at high speed onto the substrate surface to form a coating.

[0073] The composite oxides used in this application include alumina (Al₂O₃), titanium dioxide (TiO₂), and cerium oxide (CeO₂). Alumina possesses high hardness, high wear resistance, and good chemical stability; titanium dioxide exhibits excellent corrosion resistance and biocompatibility; and cerium oxide demonstrates good catalytic performance and high-temperature stability. The combination of these ceramic materials endows the composite ceramic coating with a variety of superior properties.

[0074] In the plasma spraying process, the composite oxide powder is first fed into the plasma jet of the plasma spray gun. The plasma jet has a very high temperature, which can rapidly heat and melt the ceramic powder. The molten ceramic powder is then propelled by the high-speed gas flow and sprayed onto the surface of the first rare-earth-doped high-entropy alloy coating, where it impacts and spreads to form the coating. Through multiple plasma sprays and by gradually changing the composition and proportion of the composite oxide powder, a first composite ceramic coating with a gradient content can be formed on the surface of the first rare-earth-doped high-entropy alloy coating. The gradient content design allows the composition and properties of the coating to gradually change in the thickness direction, enabling it to better adapt to different working environments and stress distributions.

[0075] Furthermore, the rare earth elements in the first rare earth-doped high-entropy alloy coating may also infiltrate into the first composite ceramic coating during the plasma spraying stage. This infiltration of rare earth elements refines the interface between the first composite ceramic coating and the first rare earth-doped high-entropy alloy coating. At the interface, the rare earth elements interact with the ceramic and alloying elements, altering the atomic arrangement and chemical bonding state, making the interface more compact and robust. This tight interfacial bonding effectively transfers stress, improves the coating's bonding strength and anti-stripping properties, thereby further enhancing the overall performance of the composite coating.

[0076] (4) Laser texturing and multilayer coating construction: Optimize coating structure and performance.

[0077] To further improve the performance of the composite coating, laser texturing is performed on the surface of the first composite ceramic coating. Laser texturing is a technique that uses a high-energy laser beam to micro-process the surface of a material. By precisely controlling the laser parameters, such as laser power, pulse frequency, and scanning speed, a first treatment layer with a honeycomb-like microstructure of specific shape and size can be formed on the surface of the first composite ceramic coating.

[0078] This honeycomb microstructure offers several advantages. First, it increases the surface roughness and specific surface area of ​​the first composite ceramic coating. During subsequent magnetron sputtering deposition, atoms from the rare-earth-containing composite target are more readily adsorbed onto the surface of these microstructures, resulting in a uniform and dense second rare-earth-doped high-entropy alloy coating. Second, the honeycomb microstructure also acts as a buffer and disperser of stress. When the composite coating is subjected to external forces, the microstructure can distribute the stress over a larger area, preventing stress concentration that could lead to cracking and peeling, thereby improving the bonding strength between the first composite ceramic coating and the second rare-earth-doped high-entropy alloy coating.

[0079] Subsequent steps including repeated plasma spraying, laser texturing, and magnetron sputtering deposition allow for the sequential formation of a second composite ceramic coating and a third rare-earth-doped high-entropy alloy coating on the surface of the second rare-earth-doped high-entropy alloy coating. The alternating superposition of these uniformly distributed rare-earth-doped high-entropy alloy coatings and composite ceramic coatings effectively disperses the stress distribution within the composite coating system. The interfaces and microstructures of the different coatings coordinate and cooperate with each other, transferring and dispersing stress throughout the coating system, preventing stress concentration in any particular area, thereby improving the hardness and strength of the composite coating.

[0080] Meanwhile, the composite ceramic coating is configured with a gradient content, allowing the composition and properties of the composite coating to vary uniformly along the thickness direction. This uniform distribution of composition and properties allows it to better adapt to changes in the external environment and the effects of stress, further dispersing the stress distribution of the composite coating and thus improving its overall performance.

[0081] (5) Material selection advantages: Reduces thermal stress and improves coating stability.

[0082] In this application, the composite target material used is AlCoCrFeNi-Y, and the composite oxides include alumina, titanium oxide, and cerium oxide. This material selection is of great significance. In practical applications, composite coatings often face temperature variations, and the differences in the coefficients of thermal expansion of different materials can lead to thermal stress within the coating. When the thermal stress is too high, it can cause the coating to crack and peel off, thereby reducing the coating's service life and performance.

[0083] The thermal expansion coefficients of the AlCoCrFeNi-Y high-entropy alloy and the composite oxides of alumina, titanium dioxide, and cerium oxide are relatively small and close. During the preparation and use of the composite coating, the difference in thermal expansion between these two materials is small when the temperature changes, effectively reducing the internal thermal stress of the composite coating. This reduction in thermal stress improves the stability and reliability of the composite coating, reduces the risk of damage during temperature changes, and further enhances its hardness and strength, enabling it to maintain good performance over a wider temperature range.

[0084] In summary, the PVD composite coating preparation method provided in this application involves a series of process steps, including pretreatment of the metal substrate, magnetron sputtering deposition of a rare-earth-doped high-entropy alloy coating, plasma spraying to form a gradient-content composite ceramic coating, laser texturing treatment, and alternating construction of multilayer coatings. Combined with carefully selected materials with low coefficients of thermal expansion, this method fully leverages the advantages of each process and material. This approach significantly improves the bonding strength, hardness, and overall strength of the composite coating, reduces thermal stress, and enhances the stability and reliability of the composite coating. In future industrial applications, it is expected to provide high-performance metal surface protection and strengthening solutions for numerous fields such as aerospace, machinery manufacturing, and electronics.

[0085] In some optional embodiments, the magnetron sputtering deposition pressure is 0.3 Pa to 0.8 Pa, and the power density of the magnetron sputtering deposition is 2 W / cm³. 2 ~4W / cm 2 The magnetron sputtering deposition voltage is -150V to -50V, the magnetron sputtering deposition temperature is 200℃ to 400℃, and the magnetron sputtering deposition time is 1.5h to 6h.

[0086] In these embodiments, the pressure for magnetron sputtering deposition can be 0.3 Pa to 0.8 Pa, and the power density for magnetron sputtering deposition can be 2 W / cm². 2 ~4W / cm 2The magnetron sputtering deposition voltage can be -150V to -50V, the magnetron sputtering deposition temperature can be 200℃ to 400℃, and the magnetron sputtering deposition time can be 1.5h to 6h, so that the composite target material can form a uniform and dense rare earth-doped high-entropy alloy coating after magnetron sputtering deposition, which facilitates the subsequent deposition of composite ceramic coatings.

[0087] The pressure for magnetron sputtering deposition can be 0.3 Pa, 0.4 Pa, 0.5 Pa, 0.6 Pa, 0.7 Pa, or 0.8 Pa.

[0088] The power density of this magnetron sputtering deposition can be 2 W / cm². 2 2.5W / cm 2 3W / cm 2 3.5W / cm 2 Or 4W / cm 2 .

[0089] The voltage for this magnetron sputtering deposition can be -150V, -140V, -130V, -120V, -110V, -100V, -90V, -80V, -70V, -60V, or -50V.

[0090] The magnetron sputtering deposition temperature can be 200℃, 220℃, 240℃, 260℃, 280℃, 300℃, 320℃, 340℃, 360℃, 380℃ or 400℃.

[0091] The magnetron sputtering deposition time can be 1.5h, 2.0h, 3.0h, 3.5h, 4.0h, 4.5h, 5.0h, 5.5h or 6.0h.

[0092] It should be noted that this magnetron sputtering deposition is powered by a DC power supply.

[0093] In some optional embodiments, the plasma spraying power is 45kW to 50kW, the plasma spraying voltage is 55V to 65V, the plasma spraying powder feed rate is 25g / min to 35g / min, and the plasma spraying distance is 80mm to 120mm.

[0094] In these embodiments, the plasma spraying power can be 45kW to 50kW, the plasma spraying voltage can be 55V to 65V, the plasma spraying powder feed rate can be 25g / min to 35g / min, and the plasma spraying distance can be 80mm to 120mm, so that the composite oxide can form a uniform and dense ceramic layer through plasma spraying. In addition, during the plasma spraying stage, the rare earth elements of the rare earth doped high entropy alloy coating may penetrate into the ceramic layer to refine the grains of the ceramic layer and optimize the grain boundaries of the ceramic layer, thereby improving the bonding strength between the rare earth doped high entropy alloy coating and the ceramic layer.

[0095] The power of the plasma spraying can be 45kW, 46kW, 47kW, 48kW, 49kW or 50kW.

[0096] The voltage for plasma spraying can be 55V, 56V, 57V, 58V, 59V, 60V, 61V, 62V, 63V, 64V or 65V.

[0097] The powder feed rate for this plasma spraying can be 25 g / min, 26 g / min, 27 g / min, 28 g / min, 29 g / min, 30 g / min, 31 g / min, 32 g / min, 33 g / min, 34 g / min or 35 g / min.

[0098] The plasma spraying distance can be 80mm, 85mm, 90mm, 95mm, 100mm, 105mm, 110mm, 115mm or 120mm.

[0099] In some optional embodiments, the mass m1 of the alumina, the mass m2 of the titanium oxide, and the mass m3 of the cerium oxide satisfy the relationship m1:m2:m3=(85~75):(5~15):10.

[0100] In these embodiments, the mass m1 of alumina, the mass m2 of titanium oxide, and the mass m3 of cerium oxide can satisfy the relationship m1:m2:m3=(85~75):(5~15):10, so that the composite oxide contains sufficient amounts of alumina, titanium oxide, and cerium oxide. The sufficient amount of alumina can serve as a matrix and react fully with cerium oxide and titanium oxide of different masses to form composite ceramic coatings with different titanium oxide gradient contents. These composite ceramic coatings with different contents can make the composition and properties gradually change in the thickness direction, which can better adapt to different working environments and stress distributions, thereby improving the hardness and strength of the composite coating.

[0101] The mass m1 of the alumina can be 85, 84, 83, 82, 81, 80, 79, 78, 77, 76 or 75.

[0102] The mass m2 of the titanium oxide can be 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 or 15.

[0103] It should be noted that the particle size of the alumina can be 25μm to 35μm; the particle size of the titanium oxide can be 30μm to 40μm; and the particle size of the cerium oxide can be 45μm to 55μm.

[0104] It should be noted that the alumina, titanium oxide and cerium oxide can be mixed using multiple powder feeders.

[0105] In some optional embodiments, the titanium oxide content of the first composite ceramic coating is distributed in a gradually increasing manner, with the difference between the mass contents of two adjacent titanium oxides being 2% to 5%; and / or

[0106] The titanium oxide content of the second composite ceramic coating decreases gradually, with the difference between the mass contents of two adjacent titanium oxide layers being 2% to 5%; and / or

[0107] The rare earth element content of the first rare earth-doped high-entropy alloy coating, the second rare earth-doped high-entropy alloy coating, and the third rare earth-doped high-entropy alloy coating is 1.5% to 2.5% by mass.

[0108] In these embodiments, the titanium oxide mass content of the first composite ceramic coating is distributed in a gradually increasing manner, with the difference between the mass contents of two adjacent titanium oxides being 2% to 5%, and the titanium oxide mass content of the second composite ceramic coating is distributed in a gradually decreasing manner, with the difference between the mass contents of two adjacent titanium oxides being 2% to 5%. This results in a uniform distribution of titanium oxide mass content in each composite ceramic coating, and the corresponding alumina mass content also exhibits an opposite distribution. This allows the composition and properties of the composite ceramic coating to gradually change in the thickness direction, enabling it to better adapt to different working environments and stress distributions, thereby improving the hardness and strength of the composite coating. In addition, the mass content of rare earth elements in the first, second, and third rare earth-doped high-entropy alloy coatings can be 1.5% to 2.5%, so that the rare earth-doped high-entropy alloy coatings have sufficient rare earth elements. These rare earth elements can not only adjust the grain and grain boundary distribution of the rare earth-doped high-entropy alloy coatings, but also adjust the grain and grain boundary distribution of the composite ceramic coatings, so as to promote the bonding strength between the rare earth-doped high-entropy alloy coatings and the composite ceramic coatings, and ultimately improve the bonding strength and hardness of the composite coatings.

[0109] The difference in mass content between two adjacent titanium dioxide atoms can be 2%, 3%, 4%, or 5%.

[0110] In some optional embodiments, the thicknesses of the first rare-earth-doped high-entropy alloy coating, the second rare-earth-doped high-entropy alloy coating, and the third rare-earth-doped high-entropy alloy coating are 5 μm to 10 μm, respectively; and / or

[0111] The thickness h1 of the first composite ceramic coating and the thickness h2 of the second composite ceramic coating satisfy the relationship: h1 + h2 = 45 μm ~ 55 μm; and / or

[0112] The pore size of a single honeycomb microstructure in the first and second processing layers is 15 μm to 25 μm, and the depth of a single honeycomb microstructure in the first and second processing layers is 3 μm to 5 μm.

[0113] In these embodiments, the thicknesses of the first, second, and third rare-earth-doped high-entropy alloy coatings can be 5 μm to 10 μm, ensuring sufficient thickness. A sufficiently thick rare-earth-doped high-entropy alloy coating can effectively improve the hardness of the composite coating. Furthermore, the thicknesses h1 of the first and second composite ceramic coatings can satisfy the relationship h1 + h2 = 45 μm to 55 μm, maintaining a high total thickness of the composite ceramic layer to ensure the bonding strength and hardness of the composite coating. Additionally, the pore size of the individual honeycomb microstructures in the first and second treatment layers can be 15 μm to 25 μm, and the depth of the individual honeycomb microstructures in the first and second treatment layers can be 3 μm to 5 μm, ensuring sufficient depth and width of the honeycomb microstructures in the treatment layers to improve the bonding strength between the rare-earth-doped high-entropy alloy coating and the composite ceramic coating, thereby enhancing the bonding strength of the composite coating.

[0114] The thicknesses of the first rare-earth-doped high-entropy alloy coating, the second rare-earth-doped high-entropy alloy coating, and the third rare-earth-doped high-entropy alloy coating can be 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, or 10 μm, respectively.

[0115] The thickness h1 of the first composite ceramic coating and the thickness h2 of the second composite ceramic coating can satisfy the following relationship: h1+h2=45μm, 46μm, 47μm, 48μm, 49μm, 50μm, 51μm, 52μm, 53μm, 54μm or 55μm.

[0116] The pore size of a single honeycomb microstructure in the first and second processing layers can be 15μm, 16μm, 17μm, 18μm, 19μm, 20μm, 212μm, 22μm, 23μm, 24μm or 25μm.

[0117] The depth of a single honeycomb microstructure in the first and second processing layers can be 3 μm, 4 μm, or 5 μm.

[0118] In some optional embodiments, the pulse energy of the laser texturing is 35μJ to 45μJ, the repetition frequency of the laser texturing is 100kHz to 500kHz, the scanning speed of the laser texturing is 100mm / s to 1000mm / s, and the spot diameter of the laser texturing is 15μm to 25μm.

[0119] In these embodiments, the pulse energy of laser texturing can be 35 μJ to 45 μJ, the repetition frequency of laser texturing can be 100 kHz to 500 kHz, the scanning speed of laser texturing can be 100 mm / s to 1000 mm / s, and the spot diameter of laser texturing can be 15 μm to 25 μm. This allows the surface of the composite ceramic layer to form a honeycomb microstructure of sufficient depth and width. These honeycomb microstructures can effectively improve the bonding strength between the rare earth-doped high-entropy alloy coating and the composite ceramic layer, and may also provide a large number of rare earth element transfer channels on both sides of the composite ceramic layer, so as to improve the grain and grain boundary distribution of the composite ceramic layer through rare earth elements, thereby further adjusting the bonding strength and compactness of the composite coating.

[0120] Figure 2 A detailed flowchart illustrating a method for preparing a PVD composite coating according to an embodiment of this application is shown as an example.

[0121] In some optional embodiments, the post-processing of the crude composite coating to obtain the composite coating includes the following steps:

[0122] S901. Anneal the crude composite coating to obtain an annealed crude composite coating;

[0123] S902. The annealed composite coating rough product is subjected to hot isostatic pressing treatment to obtain the composite coating;

[0124] The annealing temperature is 800℃~900℃, and the annealing time is 1.5h~2.5h.

[0125] The hot isostatic pressing (HIP) treatment is performed at a temperature of 900℃ to 950℃, at a pressure of 100MPa to 150MPa, and for a time of 1h to 2h.

[0126] In these embodiments, the crude composite coating is subjected to annealing and hot isostatic pressing (HIP) treatments in sequence. The annealing temperature can be 800°C to 900°C and the annealing time can be 1.5h to 2.5h. The HIP temperature can be 900°C to 950°C and the HIP pressure can be 100MPa to 150MPa. The HIP time can be 1h to 2h. This can promote the complete grain boundary diffusion reaction of the crude composite coating and ensure the closure of pores and sufficient interfacial chemical bonding of the crude composite coating.

[0127] The annealing temperature can be 800℃, 810℃, 820℃, 830℃, 840℃, 850℃, 860℃, 870℃, 880℃, 890℃ or 900℃.

[0128] The annealing time can be 1.5h, 1.6h, 1.7h, 1.8h, 1.9h, 2.0h, 2.1h, 2.2h, 2.3h, 2.4h or 2.5h.

[0129] The temperature for hot isostatic pressing can be 900℃, 910℃, 920℃, 930℃, 940℃ or 950℃.

[0130] The pressure for the hot isostatic pressing process can be 100MPa, 110MPa, 120MPa, 130MPa, 140MPa or 150MPa.

[0131] The hot isostatic pressing treatment time can be 1h, 1.1h, 1.2h, 1.3h, 1.4h, 1.5h, 1.6h, 1.7h, 1.8h, 1.9h or 2h.

[0132] In some optional embodiments, the pretreatment of the metal substrate to obtain a pretreated substrate includes the following steps:

[0133] S101. Sandblast the metal substrate to obtain a rough metal substrate;

[0134] S102. The rough metal substrate is ultrasonically cleaned to obtain a pretreated substrate.

[0135] In these embodiments, the metal substrate is subjected to sandblasting and ultrasonic cleaning in sequence. Sandblasting can roughen the surface of the metal substrate (e.g., Ra = 3 μm), and ultrasonic cleaning can remove residual debris and impurities such as grease from the surface of the metal substrate.

[0136] It should be noted that organic reagents such as ethanol or acetone can be used as cleaning agents during the ultrasonic cleaning stage.

[0137] Figure 3 An exemplary schematic diagram of a PVD composite coating provided in Embodiment 1 of this application is shown;

[0138] Figure 4 An exemplary schematic diagram of a PVD composite coating provided in Embodiment 4 of this application is shown;

[0139] Based on a general inventive concept, such as Figure 3 and Figure 4 As shown, this application provides a PVD composite coating, which is prepared by the method described above. The composite coating covers the surface of a metal substrate and includes multiple rare-earth-doped high-entropy alloy coatings and multiple composite ceramic coatings. The composite ceramic coatings and the rare-earth-doped high-entropy alloy coatings are arranged alternately, with the rare-earth-doped high-entropy alloy coatings being the outermost and innermost layers. The composite ceramic coatings and the rare-earth-doped high-entropy alloy coatings are connected and fixed by a processing layer.

[0140] The composite coating is achieved based on the above preparation method. The specific steps of the preparation method can be referred to the above embodiments. Since the composite coating adopts some or all of the technical solutions of the above embodiments, it has at least all the beneficial effects brought about by the technical solutions of the above embodiments, which will not be elaborated here.

[0141] It should be noted that this composite coating can be used on the surfaces of cutting tools, molds, and parts to improve their mechanical properties such as hardness and strength.

[0142] The present application is further illustrated below with reference to specific embodiments. Experimental methods in the following embodiments that do not specify specific conditions are generally determined according to national / industry standards; if there is no corresponding national / industry standard, they are performed according to generally accepted international standards, conventional conditions, or conditions recommended by the manufacturer.

[0143] Example 1

[0144] like Figure 2 As shown, a method for preparing a PVD composite coating includes:

[0145] S101. Sandblast the metal substrate to obtain a rough metal substrate;

[0146] S102. The rough metal substrate is ultrasonically cleaned to obtain a pretreated substrate;

[0147] S2. A first rare earth-doped high-entropy alloy coating is obtained by magnetron sputtering deposition on the surface of a pretreated substrate using a composite target containing rare earth elements.

[0148] S3. Multiple plasma sprayings are performed on the surface of the first rare earth-doped high-entropy alloy coating using composite oxides to obtain a first composite ceramic coating with gradient content.

[0149] S4. Laser texturing is performed on the first composite ceramic coating to form a honeycomb microstructure on the surface of the first composite ceramic coating, thereby obtaining the first treatment layer;

[0150] S5. A second rare earth-doped high-entropy alloy coating is obtained by magnetron sputtering deposition on the surface of the first treatment layer using a composite target containing rare earth elements.

[0151] S6. Multiple plasma sprayings are performed on the surface of the second rare earth-doped high-entropy alloy coating using composite oxides to obtain a second composite ceramic coating with gradient content.

[0152] S7. Laser texturing is performed on the second composite ceramic coating to form a honeycomb microstructure on the surface of the second composite ceramic coating, thereby obtaining the second treatment layer;

[0153] S8. A composite target containing rare earth elements is used to perform magnetron sputtering deposition on the surface of the second treatment layer to obtain a crude composite coating containing a third rare earth-doped high-entropy alloy coating.

[0154] S901. Anneal the rough composite coating product to obtain an annealed rough composite coating product;

[0155] S902. The annealed composite coating rough product is subjected to hot isostatic pressing treatment to obtain the following: Figure 3 The composite coating shown;

[0156] The annealing temperature was 850℃ and the annealing time was 2.0h.

[0157] The hot isostatic pressing (HIP) treatment temperature was 920℃, the HIP treatment pressure was 130MPa, and the HIP treatment time was 1.5h; the composite target material was AlCoCrFeNi-Y, and the composite oxides included alumina, titanium oxide, and cerium oxide.

[0158] The magnetron sputtering deposition pressure was 0.5 Pa, and the magnetron sputtering deposition power density was 3 W / cm³. 2 The magnetron sputtering deposition voltage was -100V, the magnetron sputtering deposition temperature was 300℃, and the magnetron sputtering deposition time was 4h.

[0159] The power of plasma spraying is 45kW to 50kW, the voltage is 55V to 65V, the powder feeding rate is 25g / min to 35g / min, and the spraying distance is 80mm to 120mm.

[0160] The masses of aluminum oxide (m1), titanium oxide (m2), and cerium oxide (m3) satisfy the relationship m1:m2:m3 = (85-75):(5-15):10.

[0161] The titanium dioxide content in the first composite ceramic coating gradually increases, with a difference of 2% to 3% between adjacent titanium dioxide contents. Specifically, the first composite ceramic coating consists of four layers, where the mass ratios of alumina (m1) and titanium dioxide (m2) in a single ceramic layer satisfy the following relationships: m1:m2 = 84:6, 82:8, 79:11, and 76:14, respectively. The corresponding plasma spraying powers are 50kW, 48kW, 47kW, and 46kW, the plasma spraying voltages are 65V, 61V, 58V, and 56V, the plasma spraying powder feed rates are 35g / min, 33g / min, 30g / min, and 27g / min, and the plasma spraying distances are 120mm, 100mm, 90mm, and 80mm, respectively.

[0162] The titanium dioxide content in the second composite ceramic coating decreases gradually, with a difference of 2% to 3% between adjacent titanium dioxide contents. Specifically, the second composite ceramic coating consists of four layers, where the mass ratios of alumina (m1) and titanium dioxide (m2) in each layer satisfy the following relationships: m1:m2 = 76:14, 79:11, 82:8, and 84:6, respectively. The corresponding plasma spraying powers are 46kW, 47kW, 48kW, and 50kW, the plasma spraying voltages are 65V, 61V, 58V, and 56V, the plasma spraying powder feed rates are 27g / min, 30g / min, 33g / min, and 35g / min, and the plasma spraying distances are 80mm, 90mm, 100mm, and 120mm, respectively.

[0163] The titanium oxide mass content of the first composite ceramic coating and the titanium oxide mass content of the second composite ceramic coating are symmetrically distributed around the second rare earth-doped high-entropy alloy coating.

[0164] The rare earth element content of the first, second, and third rare earth doped high-entropy alloy coatings is 2.0%.

[0165] The thickness of the first rare earth-doped high-entropy alloy coating is 5 μm, the thickness of the second rare earth-doped high-entropy alloy coating is 8 μm, and the thickness of the third rare earth-doped high-entropy alloy coating is 6 μm.

[0166] The thickness h1 of the first composite ceramic coating and the thickness h2 of the second composite ceramic coating satisfy the following relationship: h1 + h2 = 50 μm; where the thickness h1 of the first composite ceramic coating is 30 μm and the thickness h2 of the second composite ceramic coating is 20 μm.

[0167] The pore size of a single honeycomb microstructure in the first and second treatment layers is 20 μm, and the depth of a single honeycomb microstructure in the first and second treatment layers is 3 μm to 5 μm.

[0168] The pulse energy of laser texturing is 40 μJ, the repetition frequency of laser texturing is 300 kHz, the scanning speed of laser texturing is 500 mm / s, and the spot diameter of laser texturing is 20 μm.

[0169] Example 2

[0170] Based on the content disclosed in Example 1, the following modifications are made:

[0171] The magnetron sputtering deposition pressure was 0.3 Pa, and the magnetron sputtering deposition power density was 4 W / cm³. 2 The magnetron sputtering deposition voltage was -150V, the magnetron sputtering deposition temperature was 200℃, and the magnetron sputtering deposition time was 6.0h.

[0172] Example 3

[0173] Based on the content disclosed in Example 1, the following modifications are made:

[0174] The magnetron sputtering deposition pressure was 0.8 Pa, and the magnetron sputtering deposition power density was 2 W / cm³. 2 The magnetron sputtering deposition voltage was -50V, the magnetron sputtering deposition temperature was 400℃, and the magnetron sputtering deposition time was 1.5h.

[0175] Example 4

[0176] Based on the content disclosed in Example 1, the following modifications are made:

[0177] like Figure 4As shown, the titanium oxide mass content of the first composite ceramic coating is distributed in a gradually increasing manner, with the difference between the mass contents of two adjacent titanium oxides being 3% to 5%. Specifically, the first composite ceramic coating consists of three layers, wherein the mass of alumina (m1) and the mass of titanium oxide (m2) in a single ceramic coating layer satisfy the following relationships: m1:m2 = 85:5, 80:10, and 77:13, respectively. The corresponding plasma spraying powers are 50kW, 47kW, and 45kW, the plasma spraying voltages are 65V, 60V, and 55V, the plasma spraying powder feed rates are 35g / min, 30g / min, and 25g / min, and the plasma spraying distances are 120mm, 100mm, and 80mm, respectively.

[0178] The titanium dioxide content in the second composite ceramic coating decreases gradually, with a difference of 3% to 5% between adjacent titanium dioxide contents. Specifically, the second composite ceramic coating consists of three layers, where the mass ratios of alumina (m1) and titanium dioxide (m2) in each layer satisfy the following relationships: m1:m2 = 77:13, 80:10, and 85:5, respectively. The corresponding plasma spraying powers are 45kW, 47kW, and 50kW, the plasma spraying voltages are 55V, 60V, and 65V, the plasma spraying powder feed rates are 25g / min, 30g / min, and 35g / min, and the plasma spraying distances are 80mm, 100mm, and 120mm, respectively.

[0179] Example 5

[0180] Based on the content disclosed in Example 1, the following modifications are made:

[0181] The rare earth element content of the first, second, and third rare earth doped high-entropy alloy coatings is 1.5%.

[0182] Example 6

[0183] Based on the content disclosed in Example 1, the following modifications are made:

[0184] The rare earth element content of the first, second, and third rare earth doped high-entropy alloy coatings is 2.5%.

[0185] Example 7

[0186] Based on the content disclosed in Example 1, the following modifications are made:

[0187] The pore size of a single honeycomb microstructure in the first and second treatment layers is 15 μm.

[0188] The pulse energy of laser texturing is 35 μJ, the repetition frequency of laser texturing is 100 kHz, the scanning speed of laser texturing is 100 mm / s, and the spot diameter of laser texturing is 15 μm.

[0189] Example 8

[0190] Based on the content disclosed in Example 1, the following modifications are made:

[0191] The pore size of a single honeycomb microstructure in the first and second treatment layers is 25 μm.

[0192] The pulse energy of laser texturing is 45 μJ, the repetition frequency of laser texturing is 500 kHz, the scanning speed of laser texturing is 1000 mm / s, and the spot diameter of laser texturing is 25 μm.

[0193] Example 9

[0194] Based on the content disclosed in Example 1, the following modifications are made:

[0195] The annealing temperature was 800℃, and the annealing time was 2.5 hours.

[0196] The hot isostatic pressing (HIP) treatment temperature is 900℃, the HIP treatment pressure is 150MPa, and the HIP treatment time is 2h.

[0197] Example 10

[0198] Based on the content disclosed in Example 1, the following modifications are made:

[0199] The annealing temperature was 900℃, and the annealing time was 1.5h.

[0200] The hot isostatic pressing (HIP) treatment temperature is 950℃, the HIP treatment pressure is 100MPa, and the HIP treatment time is 1h.

[0201] Comparative Example 1

[0202] Based on the content disclosed in Example 1, the following modifications are made:

[0203] No magnetron sputtering deposition is performed, meaning the composite coating does not contain a rare-earth-doped high-entropy alloy coating.

[0204] The thickness h1 of the first composite ceramic coating and the thickness h2 of the second composite ceramic coating satisfy the following relationship: h1 + h2 = 69 μm; where the thickness h1 of the first composite ceramic coating is 30 μm and the thickness h2 of the second composite ceramic coating is 39 μm.

[0205] Comparative Example 2

[0206] Based on the content disclosed in Example 1, the following modifications are made:

[0207] Only one magnetron sputtering deposition and one multiple plasma spraying are performed, that is, the composite coating consists of only one first rare earth-doped high-entropy alloy coating and one first composite ceramic coating.

[0208] The thickness of the first rare earth-doped high-entropy alloy coating is 20 μm;

[0209] The thickness of the first composite ceramic coating is 50 μm.

[0210] Comparative Example 3

[0211] Based on the content disclosed in Example 1, the following modifications are made:

[0212] Only two steps of magnetron sputtering deposition, one step of multiple plasma spraying and laser texturing are performed, that is, the composite coating consists of only two rare earth-doped high-entropy alloy coatings, two composite ceramic layers and a first treatment layer.

[0213] The thickness of the first rare earth-doped high-entropy alloy coating is 5 μm, and the thickness of the second rare earth-doped high-entropy alloy coating is 8 μm.

[0214] The thickness h1 of the first composite ceramic coating and the thickness h2 of the second composite ceramic coating satisfy the following relationship: h1 + h2 = 56 μm; where the thickness h1 of the first composite ceramic coating is 33 μm and the thickness h2 of the second composite ceramic coating is 23 μm.

[0215] Comparative Example 4

[0216] Based on the content disclosed in Example 1, the following modifications are made:

[0217] The titanium oxide mass content of the first composite ceramic coating is distributed in a gradually increasing manner, and the titanium oxide mass content of the second composite ceramic coating is also distributed in a gradually increasing manner; that is, the titanium oxide mass content of the first composite ceramic coating and the titanium oxide mass content of the second composite ceramic coating are distributed with the same titanium oxide mass content gradient at the interface of the second rare earth doped high entropy alloy coating.

[0218] Comparative Example 5

[0219] Based on the content disclosed in Example 1, the following modifications are made:

[0220] The mass content of titanium oxide in the first composite ceramic coating remains consistent; specifically, the first composite ceramic coating consists of four layers, in which the mass of alumina m1 and the mass of titanium oxide m2 in a single ceramic coating layer both satisfy the relationship: m1:m2=80:10.

[0221] The mass content of titanium oxide in the second composite ceramic coating remains consistent; specifically, the second composite ceramic coating consists of four layers, wherein the mass of alumina m1 and the mass of titanium oxide m2 in a single ceramic coating layer satisfy the relationship: m1:m2=80:10.

[0222] Comparative Example 6

[0223] Based on the content disclosed in Example 1, the following modifications are made:

[0224] The pore size of a single honeycomb microstructure in the first and second treatment layers is 10 μm.

[0225] The pulse energy of laser texturing is 50 μJ, the repetition frequency of laser texturing is 300 kHz, the scanning speed of laser texturing is 100 mm / s, and the spot diameter of laser texturing is 10 μm.

[0226] Comparative Example 7

[0227] Based on the content disclosed in Example 1, the following modifications are made:

[0228] The pore size of a single honeycomb microstructure in the first and second treatment layers is 40 μm.

[0229] The pulse energy of laser texturing is 30 μJ, the repetition frequency of laser texturing is 300 kHz, the scanning speed of laser texturing is 1000 mm / s, and the spot diameter of laser texturing is 40 μm.

[0230] Relevant experimental and effect data:

[0231] The morphology of the composite coatings obtained in each embodiment and comparative example was analyzed. The specific process was as follows: the grain morphology and crystal phase of the composite coating were observed and analyzed on the surface or cross section using a scanning electron microscope and a backscatter diffraction probe. The results showed that the grain distribution of each composite coating in the embodiments of this application was uniform and the layering between grain boundaries was not obvious, while the comparative examples had various defects.

[0232] The composite coatings obtained in each embodiment and comparative example were subjected to hardness and adhesion tests, and the results are shown in Table 1. Hardness testing was performed according to GB / T 7997-2014 "Test Method for Vickers Hardness of Hard Alloys". A nanoindenter was used to test the microhardness of the composite coatings. Then, using Comparative Example 1 as a benchmark, the Vickers hardness improvement rate of each embodiment and comparative example was determined. Vickers hardness improvement rate = (Measured Vickers hardness - Vickers hardness of Comparative Example 1) / Vickers hardness of Comparative Example 1. Adhesion was measured using the scratch method to determine the film-substrate adhesion of the composite coatings. The specific procedure was as follows: a conical diamond indenter with a smooth tip was used to scratch the surface of the composite coating at a certain speed, while gradually increasing the vertical pressure of the indenter. The minimum pressure required for the coating to crack was used to characterize the film-substrate adhesion strength. The measurement parameters were: total scratch length 15 mm, scratch speed 3 mm / min; indenter pressure 0 N~120 N; loading speed 333 mN / s. Based on the acoustic signal of coating cracking collected synchronously during the scratch loading test, the critical load, i.e., the film-substrate bonding force, is determined by comparing the change in friction force when the indenter scratches the substrate after the coating cracks.

[0233] Table 1 shows the results of hardness and adhesion of the composite coatings obtained in each embodiment and comparative example.

[0234]

[0235] As shown in Table 1, the PVD composite coating preparation method provided in this application involves a series of process steps, including pretreatment of the metal substrate, magnetron sputtering deposition of rare earth-doped high-entropy alloy coating, plasma spraying to form a composite ceramic coating with gradient content, laser texturing treatment, and alternating construction of multilayer coatings. Combined with carefully selected materials with low expansion coefficients, this method fully leverages the advantages of each process and material, resulting in a composite coating with a Vickers hardness (HV) of over 2000 and an adhesion strength of over 70N. Furthermore, the composite coating exhibits uniform grain distribution and minimal delamination between grain boundaries.

[0236] Furthermore, although Comparative Example 6 is not significantly different from the embodiments, the honeycomb microstructure used in Comparative Example 6 has a smaller pore size, requiring higher laser texturing pulse energy and more precise parameter control, thus placing higher demands on the equipment and increasing equipment operating costs. Additionally, although the Vickers hardness of Comparative Example 7 is not significantly different from the embodiments, its bonding strength is poor. Moreover, compared to Embodiment 4 of this application, this application achieves the same bonding strength using a three-layer composite ceramic coating, indirectly demonstrating that large-pore honeycomb microstructures deteriorate bonding strength.

[0237] In summary, the PVD composite coating preparation method provided in this application involves a series of process steps, including pretreatment of the metal substrate, magnetron sputtering deposition of rare earth-doped high-entropy alloy coating, plasma spraying to form a composite ceramic coating with gradient content, laser texturing treatment, and alternating construction of multilayer coatings. Combined with carefully selected materials with low expansion coefficients, this method can significantly improve the bonding strength, hardness, and strength of the composite coating.

[0238] In addition, this application provides a method for preparing a PVD composite coating. The composite coating obtained by this method can be widely used on the surface of cutting tools, lathe molds and other metal parts to improve the surface mechanical properties of these metal parts.

[0239] In addition, the present application provides a method for preparing a PVD composite coating. The composite coating obtained by this method can also be used for coating high-temperature aerospace components or high-load cutting tools.

[0240] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed in this application.

Claims

1. A method for preparing a PVD composite coating, characterized in that, The preparation method includes: The metal substrate is pretreated to obtain a pretreated substrate; A first rare-earth-doped high-entropy alloy coating is obtained by magnetron sputtering deposition on the surface of the pretreated substrate using a composite target containing rare earth elements. Multiple plasma sprayings were performed on the surface of the first rare earth-doped high-entropy alloy coating using composite oxides to obtain a first composite ceramic coating with gradient content. The first composite ceramic coating is laser-textured to form a honeycomb microstructure on the surface of the first composite ceramic coating, thus obtaining a first treatment layer; The composite target containing rare earth elements is used to perform magnetron sputtering deposition on the surface of the first processed layer to obtain a second rare earth-doped high-entropy alloy coating. The composite oxide is used to perform multiple plasma sprayings on the surface of the second rare earth-doped high-entropy alloy coating to obtain a second composite ceramic coating with gradient content. The second composite ceramic coating is subjected to laser texturing to form a honeycomb microstructure on the surface of the second composite ceramic coating, thereby obtaining a second treatment layer; The composite target containing rare earth elements is used to perform magnetron sputtering deposition on the surface of the second treatment layer to obtain a crude composite coating containing a third rare earth-doped high-entropy alloy coating. The crude composite coating is then post-processed to obtain the composite coating. The composite target material is AlCoCrFeNi-Y, and the composite oxide includes alumina, titanium oxide, and cerium oxide. The mass m1 of the alumina, the mass m2 of the titanium oxide, and the mass m3 of the cerium oxide satisfy the relationship m1:m2:m3=(85~75):(5~15):

10. The mass content of titanium oxide in the first composite ceramic coating is distributed in a gradually increasing state, and the difference between the mass contents of two adjacent titanium oxides is 2%~5%. The titanium oxide content of the second composite ceramic coating is distributed in a gradually decreasing manner, with the difference between the mass contents of two adjacent titanium oxides being 2% to 5%. The rare earth element content of the first rare earth-doped high-entropy alloy coating, the second rare earth-doped high-entropy alloy coating, and the third rare earth-doped high-entropy alloy coating is 1.5% to 2.5% by mass; the thickness of the first rare earth-doped high-entropy alloy coating, the second rare earth-doped high-entropy alloy coating, and the third rare earth-doped high-entropy alloy coating is 5 μm to 10 μm, respectively. The thickness h1 of the first composite ceramic coating and the thickness h2 of the second composite ceramic coating satisfy the relationship: h1 + h2 = 45 μm ~ 55 μm; The pore size of a single honeycomb microstructure in the first processing layer and the second processing layer is 15μm to 25μm, and the depth of a single honeycomb microstructure in the first processing layer and the second processing layer is 3μm to 5μm. The pulse energy of the laser texturing is 35μJ to 45μJ, the repetition frequency of the laser texturing is 100kHz to 500kHz, the scanning speed of the laser texturing is 100mm / s to 1000mm / s, and the spot diameter of the laser texturing is 15μm to 25μm.

2. The preparation method according to claim 1, characterized in that, The magnetron sputtering deposition pressure is 0.3 Pa to 0.8 Pa, and the power density of the magnetron sputtering deposition is 2 W / cm³. 2 ~4W / cm 2 The magnetron sputtering deposition voltage is -150V to -50V, the magnetron sputtering deposition temperature is 200℃ to 400℃, and the magnetron sputtering deposition time is 1.5h to 6h.

3. The preparation method according to claim 1, characterized in that, The plasma spraying power is 45kW to 50kW, the plasma spraying voltage is 55V to 65V, the plasma spraying powder feed rate is 25g / min to 35g / min, and the plasma spraying distance is 80mm to 120mm.

4. The preparation method according to claim 1, characterized in that, The step of post-processing the crude composite coating to obtain the composite coating includes the following steps: The crude composite coating is annealed to obtain an annealed crude composite coating. The annealed composite coating rough product is subjected to hot isostatic pressing treatment to obtain the composite coating; The annealing temperature is 800℃~900℃, and the annealing time is 1.5h~2.5h. The hot isostatic pressing (HIP) treatment is performed at a temperature of 900℃ to 950℃, at a pressure of 100MPa to 150MPa, and for a time of 1h to 2h.

5. The preparation method according to claim 1, characterized in that, The process of pretreating the metal substrate to obtain a pretreated substrate includes the following steps: A rough metal substrate is obtained by sandblasting the metal substrate. The rough metal substrate is ultrasonically cleaned to obtain a pretreated substrate.

6. A PVD composite coating, characterized in that, The composite coating is prepared by the method according to any one of claims 1 to 4; the composite coating covers the surface of the metal substrate, and the composite coating includes multiple rare earth-doped high-entropy alloy coatings and multiple composite ceramic coatings, wherein the composite ceramic coatings and the rare earth-doped high-entropy alloy coatings are arranged alternately, and the rare earth-doped high-entropy alloy coatings are the outermost and innermost layers. The composite ceramic coating and the rare earth-doped high-entropy alloy coating are connected and fixed by a treatment layer.

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