PVD (Physical Vapor Deposition) composite coating and preparation method thereof

Abstract

The invention relates to the technical field of metal material coatings, in particular to a PVD composite coating and a preparation method thereof. The preparation method comprises the following steps: pretreating a metal matrix to obtain a pretreated matrix; carrying out magnetron sputtering deposition on the surface of the pretreated matrix by using a composite target material, carrying out plasma spraying and laser texturing for multiple times, and repeating the process to form a composite coating crude product containing a third rare earth doped high-entropy alloy coating; the composite coating crude product is subjected to post-treatment, and the composite coating is obtained; wherein the composite target material is AlCoCrFeNi-Y, and the composite oxide comprises aluminum oxide, titanium oxide and cerium oxide. According to the preparation method, the bonding strength, hardness and strength of the composite coating can be remarkably improved through magnetron sputtering deposition of the rare earth doped high-entropy alloy coating, plasma spraying formation of the composite ceramic coating with the gradient content, laser texturing treatment, alternate construction of multiple layers of coatings and the like in combination with elaborately selected materials with low expansion coefficients.

Description

Technical Field

[0001] The present application relates to the technical field of metal material coatings, and particularly relates to a PVD composite coating and a preparation method thereof. Background Art

[0002] Advanced ceramic materials have very excellent strength and chemical stability and have been widely used in various wear-resistant and corrosion-resistant occasions. Among them, oxide ceramics have been widely used in various fields with high hardness requirements. The most widely used of these oxide ceramics is alumina. However, alumina-based ceramics currently have two major disadvantages: (1) The brittleness of ceramic materials is relatively large and the resistance to thermal shock and thermal impact is relatively low, which makes it difficult for ceramic materials to meet the application scenario 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 existing alumina ceramic coating, the particle size is generally large, resulting in a low bonding strength between the ceramic coating and the substrate material, and the coating structure is relatively loose, and situations such as fragmentation of the ceramic coating are likely to occur.

[0003] At present, rare earth-doped high-entropy alloy coatings are widely used in the coatings of mechanical tools due to their advantages of high strength, high density, no cracks and no shrinkage defects. Therefore, if a rare earth-doped high-entropy alloy coating is introduced into a ceramic coating, it will undoubtedly effectively improve the hardness and bonding strength of the ceramic coating. However, if the rare earth-doped high-entropy alloy coating and the ceramic coating are directly laminated and combined, due to the hardness difference between the ceramic coating and the rare earth-doped high-entropy alloy coating, the existence of the hardness difference will cause cracks in the ceramic coating during the preparation stage, and the advantages of the two cannot be effectively combined. Instead, it will further exacerbate the deficiencies in the hardness and bonding strength of the ceramic coating. Summary of the Invention

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

[0005] In a first aspect, the present application provides a preparation method of a PVD composite coating, and the preparation method includes:

[0006] Pretreat a metal substrate to obtain a pretreated substrate;

[0007] Perform magnetron sputtering deposition on the surface of the pretreated substrate using a composite target containing rare earth elements to obtain a first rare earth-doped high-entropy alloy coating;

[0008] Perform multiple plasma sprayings on the surface of the first rare earth-doped high-entropy alloy coating using a composite oxide to obtain a first composite ceramic coating with a gradient content;

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

[0010] The magnetron sputtering deposition is carried out on the surface of the first treatment layer using the composite target containing rare earth elements, obtaining a second rare earth-doped high-entropy alloy coating;

[0011] The plasma spraying is carried out on the surface of the second rare earth-doped high-entropy alloy coating for multiple times using the composite oxide, obtaining a second composite ceramic coating with a gradient content;

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

[0013] The magnetron sputtering deposition is carried out on the surface of the second treatment layer using the composite target containing rare earth elements, obtaining a rough composite coating containing a third rare earth-doped high-entropy alloy coating;

[0014] The rough composite coating is post-treated to obtain a composite coating;

[0015] Wherein, the composite target is AlCoCrFeNi-Y, and the composite oxide includes alumina, titanium oxide and cerium oxide.

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

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

[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 relational expression m1:m2:m3 = (85 - 75):(5 - 15):10.

[0019] Optionally, 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 adjacent titanium oxides is 2% to 5%; and / or

[0020] The mass content of titanium oxide in the second composite ceramic coating is distributed in a gradually decreasing state, and the difference between the mass contents of adjacent titanium oxides is 2% to 5%; and / or

[0021] The mass content of rare earth elements in 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%.

[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 5 μm to 10 μm respectively; 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 to 55 μm; and / or

[0024] The pore diameter of a single honeycomb microstructure of the first treatment layer and the second treatment layer is 15 μm to 25 μm, and the depth of a single honeycomb microstructure of the first treatment layer and the second treatment layer is 3 μm to 5 μm.

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

[0026] Optionally, the post-treatment of the composite coating rough product to obtain a composite coating includes the steps of:

[0027] Annealing the composite coating rough product to obtain an annealed composite coating rough product;

[0028] Performing hot isostatic pressing on the annealed composite coating rough product to obtain a composite coating;

[0029] Among them, the temperature of the annealing treatment is 800 °C to 900 °C, and the time of the annealing treatment is 1.5 h to 2.5 h;

[0030] The temperature of the hot isostatic pressing treatment is 900 °C to 950 °C, the pressure of the hot isostatic pressing treatment is 100 MPa to 150 MPa, and the time of the hot isostatic pressing treatment is 1 h to 2 h.

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

[0032] Sandblast the metal substrate to obtain a rough metal substrate;

[0033] Ultrasonically clean the rough metal substrate to obtain a pretreated substrate.

[0034] In a second aspect, the present application provides a PVD composite coating, which is prepared by the method described in the first aspect; the composite coating covers the surface of the metal substrate, and the composite coating includes a plurality of rare-earth doped high-entropy alloy coatings and a plurality of composite ceramic coatings, and 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 layer and the innermost layer; the composite ceramic coatings and the rare-earth doped high-entropy alloy coatings are connected and fixed through a treatment layer.

[0035] The above technical solutions provided by the embodiments of the present application have the following advantages compared with the prior art:

[0036] A method for preparing a PVD composite coating provided by an embodiment of the present application. In this preparation method, the metal substrate is first pretreated to remove impurities on the surface of the metal substrate, and then a composite target containing rare earth elements is used to form a first rare earth-doped high-entropy alloy coating on the surface of the pretreated substrate through magnetron sputtering deposition. Then, a composite oxide is used to form a first composite ceramic coating with a gradient content on the surface of the first rare earth-doped high-entropy alloy coating through multiple plasma sprayings. Based on the relatively high rare earth element content in the first rare earth-doped high-entropy alloy coating, the rare earth elements can be used to refine the grains of the metal elements in the first rare earth-doped high-entropy alloy coating and optimize the grain boundary distribution of the first rare earth-doped high-entropy alloy coating, so that a dense and high-strength first rare earth-doped high-entropy alloy coating can be obtained. In addition, these rare earth elements may also penetrate 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, making the first composite ceramic coating and the first rare earth-doped high-entropy alloy coating firmly bonded, and further improving the bonding strength of the composite coating. In addition, laser texturing can be used to form a first treatment layer with a honeycomb microstructure on the surface of the first composite ceramic coating. During the subsequent magnetron sputtering deposition process, the composite target containing rare earth elements can form a uniform and dense second rare earth-doped high-entropy alloy coating on the surface of the first composite ceramic coating and improve the bonding strength between the first composite ceramic coating and the second rare earth-doped high-entropy alloy coating. Through subsequent repeated steps such as plasma spraying, laser texturing, and magnetron sputtering deposition, a second composite ceramic coating and a third rare earth-doped high-entropy alloy coating can be formed on the surface of the second rare earth-doped high-entropy alloy coating. Through these uniformly distributed rare earth-doped high-entropy alloy coatings and composite ceramic coatings, the stress distribution of the composite coating can be dispersed to improve the hardness and strength of the composite coating; in addition, by setting the composite ceramic coating to have a gradient content, the composition and properties of the composite coating can be evenly distributed to further disperse the stress distribution of the composite coating, thereby improving the hardness and strength of the composite coating. In addition, the composite target uses AlCoCrFeNi-Y and the composite oxide may include alumina, titanium oxide, and cerium oxide. Using two materials with low coefficients of thermal expansion can further reduce the thermal stress of the composite coating to improve the hardness and strength of the composite coating. Brief Description of the Drawings

[0037] The accompanying drawings herein are incorporated into the specification and form a part of this specification, showing embodiments consistent with the present application, and are used together with the specification to explain the principles of the present application.

[0038] To more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required in the description of the embodiments or the prior art. Obviously, for those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0039] Figure 1 Schematic flow chart of a method for preparing a PVD composite coating provided by an embodiment of the present application;

[0040] Figure 2 Detailed flow chart of a method for preparing a PVD composite coating provided by an embodiment of the present application;

[0041] Figure 3 Schematic structural diagram of a PVD composite coating provided by Embodiment 1 of the present application;

[0042] Figure 4 Schematic structural diagram of a PVD composite coating provided by Embodiment 4 of the present application. Detailed implementation manners

[0043] To make the objectives, technical solutions and advantages of the embodiments of the present application clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present application with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all of them. Based on the embodiments of the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope protected by the present application.

[0044] The various embodiments of the present application may exist in the form of a range; it should be understood that the description in the form of a range is only for convenience and brevity, and should not be construed as a rigid limitation on the scope of the present application; therefore, it should be considered that the described range description has specifically disclosed all possible sub-ranges and single 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 that range, such as 1, 2, 3, 4, 5, and 6, regardless of what the range is; in addition, whenever a numerical range is indicated herein, it means including any cited number (fraction or integer) within the indicated range.

[0045] In this text, terms including "comprising" and the like mean "including but not limited to". Relative terms such as "first" and "second" are only used 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", which describes the associated relationship of associated objects, indicates that three relationships can exist. For example, A and / or B can mean: A exists alone, A and B exist simultaneously, or B exists alone; where A and B can be singular or plural. "At least one" means one or more, and "multiple" means two or more; "at least one kind", "at least one of the following items (pieces)" or similar expressions refer to any combination of these items, including any combination of single items (pieces) or plural items (pieces); 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, a - b (i.e., a and b), a - c, b - c, or a - b - c, where a, b, and c can be single or multiple respectively. "Parts representation method" such as parts by weight, parts by mass, etc. represents the proportional relationship between each component. In the proportional relationships involved in this text, the parameters that need to be described by proportion should be understood as the antecedents of the proportion formula in the order of description, and the proportional numbers should be understood as the consequents of the proportion formula. For example, if the mass ratio of substance A, substance B, and substance C is 1:2:3, then substance A, substance B, and substance C should correspond one by one with the proportional numbers in the proportion formula 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 specifically stated, all kinds of raw materials, reagents, instruments, equipment, etc. used in this text can be obtained through market purchase or can be 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 not only depends on the hardness of the ceramic materials, but more on the toughness of the ceramic materials. And ceramic materials with refined grains can undoubtedly increase strength and toughness simultaneously, thereby improving the wear resistance of ceramic materials. However, simply refining the grains of ceramic materials not only has a relatively high cost, but also the cost of ceramic materials with fine grains is relatively high.

[0048] Therefore, a rare-earth-doped high-entropy alloy coating can be introduced. Based on the rare-earth elements in the rare-earth-doped high-entropy alloy coating, the grains and grain boundaries 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 expansion coefficients between the materials of the rare-earth-doped high-entropy alloy coating and the ceramic material, as well as the differences in the compatibility between the rare-earth-doped high-entropy alloy coating and the ceramic coating, the existence of these differences will make it difficult for the rare-earth-doped high-entropy alloy coating and the ceramic coating to fit perfectly, resulting in the bonding interface being prone to offset or cracking, which will instead increase the brittleness of the ceramic coating and affect the quality of the final coating.

[0049] Figure 1 Exemplarily, a schematic flow chart of a preparation method of a PVD composite coating provided by an embodiment of the present application is shown;

[0050] As Figure 1 shown, a preparation method of a PVD composite coating provided by an embodiment of the present application, the preparation method includes:

[0051] S1. Pretreat the metal substrate to obtain a pretreated substrate;

[0052] S2. Perform magnetron sputtering deposition on the surface of the pretreated substrate using a composite target containing rare-earth elements to obtain a first rare-earth-doped high-entropy alloy coating;

[0053] S3. Perform multiple plasma sprayings on the surface of the first rare-earth-doped high-entropy alloy coating using a composite oxide to obtain a first composite ceramic coating with a gradient content;

[0054] S4. Laser texture the first composite ceramic coating to form a honeycomb microstructure on the surface of the first composite ceramic coating to obtain a first treated layer;

[0055] S5. Perform the magnetron sputtering deposition on the surface of the first treated layer using the composite target containing rare-earth elements to obtain a second rare-earth-doped high-entropy alloy coating;

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

[0057] S7. Laser texture the second composite ceramic coating to form a honeycomb microstructure on the surface of the second composite ceramic coating to obtain a second treated layer;

[0058] S8. Perform the magnetron sputtering deposition on the surface of the second treated layer using the composite target containing rare-earth elements to obtain a composite coating rough product containing a third rare-earth-doped high-entropy alloy coating;

[0059] S9. Post-treat the crude composite coating to obtain a composite coating;

[0060] Among them, the composite target is AlCoCrFeNi-Y, and the composite oxide includes alumina, titanium oxide and cerium oxide.

[0061] It should be noted that after the laser texturing, it can also be cleaned with dilute hydrochloric acid and hydrofluoric acid to wash away 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 metal materials are becoming increasingly stringent. For example, in the aerospace field, components need to work in extreme environments such as high temperature, high speed, and strong corrosion; in the machinery manufacturing industry, tools and dies need to have 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 metal materials, is playing an increasingly important role. A preparation method of a PVD composite coating provided by an embodiment of the present application is expected to significantly improve the comprehensive performance of the composite coating through a series of unique process steps and carefully selected materials. The specific principle is as follows:

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

[0064] During the processing, storage, and transportation of the metal substrate, its surface will inevitably be contaminated with various impurities, such as oil stains, dust, and scale. The presence of these impurities will seriously affect the bonding force between the subsequent coating and the substrate, resulting in easy peeling of the coating, thereby reducing the protection and strengthening effects of the coating. Therefore, the pretreatment of the metal substrate is the key starting step of the entire preparation process. The pretreatment process usually includes multiple links.

[0065] First is the degreasing treatment, generally using chemical degreasing method, immersing the metal substrate in a solution containing degreaser. The degreaser can chemically react with the oil stain to make it separate from the metal surface. Common degreasers include alkaline degreasers and organic solvent degreasers. Alkaline degreasers have lower cost and are environmentally friendly, but their removal effect on some stubborn oil stains may be limited; organic solvent degreasers have strong degreasing ability, but have certain volatility and toxicity, and safety protection needs to be paid attention to during use. After degreasing, the metal substrate also needs to be rust-removed and scale-removed. For mildly rusted metals, pickling method can be used, immersing the substrate in dilute acid solutions such as hydrochloric acid and sulfuric acid. The acid chemically reacts with rust and scale to dissolve and remove them. However, the acid concentration and immersion time need to be strictly controlled during pickling to avoid over-corroding the metal substrate. For severely rusted metals, mechanical methods such as sandblasting or shot peening can be used. By high-speed spraying abrasives to impact the metal surface, rust and scale are removed, and at the same time, the roughness of the metal surface can be increased, 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, the surface becomes clean and has a certain roughness, providing a good foundation for the subsequent deposition of the coating.

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

[0068] After completing the pretreatment of the metal substrate, next, a composite target containing rare-earth elements is used for magnetron sputtering deposition on the surface of the pretreated substrate to form the first rare-earth doped high-entropy alloy coating. Magnetron sputtering is an advanced physical vapor deposition technology. Its working principle is that in a vacuum environment, through the combined action of an electric field and a magnetic field, inert gases such as argon are ionized to form plasma. The argon ions in the plasma are accelerated by the electric field to bombard the surface of the composite target, sputtering out the atoms in the target. These atoms are deposited on the substrate surface and form a coating.

[0069] The composite target used in this application is AlCoCrFeNi-Y, which is a typical high-entropy alloy target, containing various main metal elements such as aluminum (Al), cobalt (Co), chromium (Cr), iron (Fe), nickel (Ni), and adding rare-earth element yttrium (Y). High-entropy alloys have a unique crystal structure and excellent properties. The presence of multiple main elements makes the atomic arrangement of the alloy more complex, with a higher mixing entropy, thus endowing the alloy with good strength, hardness, wear resistance, and corrosion resistance and other properties.

[0070] The addition of rare earth element yttrium further improves the performance of the high-entropy alloy coating. During the coating formation process, rare earth element yttrium can play a role in refining grains and optimizing the grain boundary distribution. When metal atoms in the coating deposit and crystallize on the substrate surface, rare earth element yttrium will preferentially adsorb at the grain boundaries, hindering the further growth of grains, thus reducing the grain size. Grain refinement can increase the number of grain boundaries. As obstacles to atomic movement, grain boundaries can effectively hinder the movement of dislocations, improving the strength and hardness of the coating. At the same time, rare earth element yttrium can also reduce the energy of grain boundaries, making the grain boundaries more stable, reducing the aggregation of defects and impurities at the grain boundaries, optimizing the grain boundary distribution, and further improving the performance of the coating. Finally, through the 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) Form a first composite ceramic coating with gradient content by plasma spraying: enhance the bonding ability and performance of the coating.

[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 sprayings using composite oxides. Plasma spraying is a technique that uses a high-temperature plasma to heat and melt ceramic powder and spray it onto the substrate surface at high speed to form a coating.

[0073] The composite oxides used in this application include alumina (Al 2 O 3 ), titanium oxide (TiO 2 ), and cerium oxide (CeO 2 ). Alumina has high hardness, high wear resistance, and good chemical stability; titanium oxide has excellent corrosion resistance and biocompatibility; cerium oxide has good catalytic performance and high-temperature stability. The combination of these ceramic materials endows the composite ceramic coating with various excellent properties.

[0074] During the plasma spraying process, first, the composite oxide powder is fed into the plasma jet of the plasma spray gun. The temperature of the plasma jet is very high, which can quickly heat and melt the ceramic powder. The melted ceramic powder is sprayed onto the surface of the first rare earth-doped high-entropy alloy coating under the drive of a high-speed gas flow, hitting and spreading to form a coating. By multiple plasma sprayings and gradually changing the composition and proportion of the composite oxide powder, a first composite ceramic coating with gradient content can be formed on the surface of the first rare earth-doped high-entropy alloy coating. The design of gradient content enables the composition and performance of the coating to gradually change in the thickness direction, which can better adapt to different working environments and stress distributions.

[0075] In addition, during the plasma spraying process, the rare earth elements in the first rare earth-doped high-entropy alloy coating may also penetrate into the first composite ceramic coating. The penetration of rare earth elements can refine the contact 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 alloy elements, changing the atomic arrangement and chemical bonding state of the interface, making the interface tighter and stronger. This tight interface bonding can effectively transfer stress, improve the bonding strength and anti-spalling performance of the coating, and further enhance the overall performance of the composite coating.

[0076] (4) Laser texturing and multi-layer coating construction: Optimize the coating structure and performance.

[0077] To further improve the performance of the composite coating, laser texturing treatment is carried out on the surface of the first composite ceramic coating. Laser texturing is a technology that uses high-energy laser beams to micro-machine the surface of materials. By precisely controlling the laser parameters, such as laser power, pulse frequency, scanning speed, etc., 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-like microstructure has many advantages. First of all, it increases the surface roughness and specific surface area of the first composite ceramic coating. During the subsequent magnetron sputtering deposition process, the atoms in the composite target containing rare earth elements are more likely to adsorb on the surface of these microstructures, thus forming a uniform and dense second rare earth-doped high-entropy alloy coating. Secondly, the honeycomb-like microstructure can also play a role in buffering and dispersing stress. When the composite coating is subjected to external forces, the microstructure can disperse the stress to a larger area, avoiding stress concentration leading to cracking and spalling of the coating, thereby improving the bonding strength between the first composite ceramic coating and the second rare earth-doped high-entropy alloy coating.

[0079] Subsequently, through repeated steps such as plasma spraying, laser texturing, and magnetron sputtering deposition, a second composite ceramic coating and a third rare earth-doped high-entropy alloy coating can be successively formed on the surface of the second rare earth-doped high-entropy alloy coating. Through the alternating stacking of these uniformly distributed rare earth-doped high-entropy alloy coatings and composite ceramic coatings, the stress distribution of the composite coating can be effectively dispersed. The interfaces and microstructures between different coatings can coordinate and cooperate with each other, transfer and disperse the stress in the coating system, avoid stress concentration in a certain area, and thus improve the hardness and strength of the composite coating.

[0080] At the same time, the composite ceramic coating is set with a gradient content, so that the composition and performance of the composite coating change uniformly in the thickness direction. This uniformly distributed composition and performance can better adapt to the changes in the external environment and the action of stress, further disperse the stress distribution of the composite coating, and thus improve the comprehensive performance of the composite coating.

[0081] (5) Material selection advantage: reducing thermal stress and enhancing coating stability.

[0082] In this application, the composite target uses 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 changes. The difference in thermal expansion coefficients of different materials will cause thermal stress inside the coating. When the thermal stress is too large, it will lead to coating cracking and peeling, thus reducing the service life and performance of the coating.

[0083] The thermal expansion coefficients of the AlCoCrFeNi-Y high-entropy alloy and the composite oxides of alumina, titanium oxide, and cerium oxide are relatively small and close to each other. During the preparation and use of the composite coating, when the temperature changes, the thermal expansion difference between these two materials is small, which can effectively reduce the thermal stress inside the composite coating. The reduction of thermal stress can improve the stability and reliability of the composite coating, reduce the damage risk of the coating during temperature changes, and further improve the hardness and strength of the composite coating, enabling it to maintain good performance within a wider temperature range.

[0084] In summary, a method for preparing a PVD composite coating provided by an embodiment of this application. Through a series of process steps such as pre-treating the metal substrate, magnetron sputtering to deposit a rare-earth doped high-entropy alloy coating, plasma spraying to form a composite ceramic coating with a gradient content, laser texturing treatment, and alternating construction of multi-layer coatings, combined with carefully selected materials with low expansion coefficients, the advantages of each process and material are fully utilized. This method can significantly improve the bonding strength, hardness, and strength of the composite coating, reduce the thermal stress of the coating, and make the composite coating have better stability and reliability. In future industrial applications, it is expected to provide high-performance metal surface protection and strengthening solutions for many fields such as aerospace, mechanical manufacturing, and electronics.

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

[0086] In these embodiments, the pressure of the magnetron sputtering deposition can be 0.3 Pa to 0.8 Pa, and the power density of the magnetron sputtering deposition can be 2 W / cm 2 ~4 W / cm 2, and the voltage of magnetron sputtering deposition can be -150V to -50V, and the temperature of magnetron sputtering deposition can be 200°C to 400°C, and the time of magnetron sputtering deposition can be 1.5h to 6h, so that a uniform and dense rare earth-doped high-entropy alloy coating can be formed after the composite target is treated by magnetron sputtering deposition, facilitating the subsequent deposition of the composite ceramic coating.

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

[0088] The power density of the magnetron sputtering deposition can be 2W / cm 2 、2.5W / cm 2 、3W / cm 2 、3.5W / cm 2 or 4W / cm 2 .

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

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

[0091] The time of the magnetron sputtering deposition 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 the magnetron sputtering deposition uses a DC power supply as the power source.

[0093] In some alternative embodiments, 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.

[0094] In these embodiments, the power of the plasma spraying can be 45 kW to 50 kW, and the voltage of the plasma spraying can be 55 V to 65 V, and the powder feeding rate of the plasma spraying can be 25 g / min to 35 g / min, and the spraying distance of the plasma spraying can be 80 mm to 120 mm, so that the composite oxide can form a uniform and dense ceramic layer through plasma spraying. Additionally, during the plasma spraying stage, the rare earth elements in 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 45 kW, 46 kW, 47 kW, 48 kW, 49 kW or 50 kW.

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

[0097] The powder feeding rate of the 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 spraying distance of the plasma spraying can be 80 mm, 85 mm, 90 mm, 95 mm, 100 mm, 105 mm, 110 mm, 115 mm or 120 mm.

[0099] In some alternative 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 the alumina, the mass m2 of the titanium oxide, and the mass m3 of the cerium oxide can satisfy the relationship m1:m2:m3 = (85 - 75):(5 - 15):10, so that there is a sufficient amount of alumina, titanium oxide, and cerium oxide in the composite oxide. The sufficient amount of alumina can serve as a matrix and react fully with cerium oxide and titanium oxide with different masses, thereby forming a composite ceramic coating with different titanium oxide gradient contents. These composite ceramic coatings with different contents can enable the composition and properties to gradually change in the thickness direction, being able to better adapt to different working environments and stress distributions to improve the hardness and strength of the composite coating.

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

[0102] The value of 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 aluminum oxide can be 25 μm to 35 μm; the particle size of the titanium oxide can be 30 μm to 40 μm; the particle size of the cerium oxide can be 45 μm to 55 μm.

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

[0105] In some alternative embodiments, 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% to 5%; and / or

[0106] The mass content of titanium oxide in the second composite ceramic coating is distributed in a gradually decreasing state, and the difference between the mass contents of two adjacent titanium oxides is 2% to 5%; and / or

[0107] The mass content of rare earth elements in 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%.

[0108] In these embodiments, 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 can be 2% to 5%, and the mass content of titanium oxide in the second composite ceramic coating is distributed in a gradually decreasing state, and the difference between the mass contents of two adjacent titanium oxides can be 2% to 5%, so that the mass content of titanium oxide in each composite ceramic coating shows a uniform distribution, and the corresponding mass content of aluminum oxide also shows an opposite mass content distribution, so that the composition and properties of the composite ceramic coating change gradually 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. In addition, the mass content of rare earth elements in 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 1.5% to 2.5%, so that the rare earth-doped high-entropy alloy coating has a sufficient amount of rare earth elements. These rare earth elements can not only adjust the grain and grain boundary distributions of the rare earth-doped high-entropy alloy coating, but also adjust the grain and grain boundary distributions of the composite ceramic coating, so as to promote the bonding strength between the rare earth-doped high-entropy alloy coating and the composite ceramic coating, and finally improve the bonding strength and hardness of the composite coating.

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

[0110] In some alternative 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 respectively 5 μm to 10 μm; 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 to 55 μm; and / or

[0112] The pore diameter of a single honeycomb microstructure of the first treatment layer and the second treatment layer is 15 μm to 25 μm, and the depth of a single honeycomb microstructure of the first treatment layer and the second treatment layer is 3 μm to 5 μm.

[0113] In these 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 can be respectively 5 μm to 10 μm, so as to enable the rare earth doped high entropy alloy coating to have a sufficient thickness. The rare earth doped high entropy alloy coating with a sufficient thickness can effectively improve the hardness of the composite coating; in addition, the thickness h1 of the first composite ceramic coating and the thickness h2 of the second composite ceramic coating can satisfy the relationship: h1 + h2 = 45 μm to 55 μm, so that the total thickness of the composite ceramic layer is maintained at a relatively high level to ensure the bonding strength and hardness of the composite coating. Furthermore, the pore diameter of a single honeycomb microstructure of the first treatment layer and the second treatment layer can be 15 μm to 25 μm, and the depth of a single honeycomb microstructure of the first treatment layer and the second treatment layer can be 3 μm to 5 μm, so that the honeycomb microstructure of the treatment layer has sufficient depth and width to improve the bonding strength between the rare earth doped high entropy alloy coating and the composite ceramic coating, thereby improving 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 respectively 5 μm, 6 μm, 7 μm, 8 μm, 9 μm or 10 μm.

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

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

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

[0118] In some alternative 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 the laser texturing can be 35μJ to 45μJ, and the repetition frequency of the laser texturing can be 100kHz to 500kHz, and the scanning speed of the laser texturing can be 100mm / s to 1000mm / s, and the spot diameter of the laser texturing can be 15μm to 25μm, so that honeycomb microstructures with sufficient depth and width can be formed on the surface of the composite ceramic layer. Through these honeycomb microstructures, the bonding strength between the rare earth doped high entropy alloy coating and the composite ceramic layer can be effectively improved, and a large number of transfer channels for rare earth elements can also be provided on both sides of the composite ceramic layer to improve the grain and grain boundary distribution of the composite ceramic layer through rare earth elements, thereby further adjusting the bonding strength and denseness of the composite coating.

[0120] Figure 2 Exemplarily, a detailed process schematic diagram of a method for preparing a PVD composite coating provided by an embodiment of the present application is shown;

[0121] In some alternative embodiments, the post-treatment of the composite coating rough product to obtain a composite coating includes the steps of:

[0122] S901. Annealing the composite coating rough product to obtain an annealed composite coating rough product;

[0123] S902. Performing hot isostatic pressing on the annealed composite coating rough product to obtain a composite coating;

[0124] Wherein, the temperature of the annealing treatment is 800°C to 900°C, and the time of the annealing treatment is 1.5h to 2.5h;

[0125] The temperature of the hot isostatic pressing treatment is 900°C to 950°C, the pressure of the hot isostatic pressing treatment is 100MPa to 150MPa, and the time of the hot isostatic pressing treatment is 1h to 2h.

[0126] In these embodiments, the as-cast composite coating is annealed and then hot isostatically pressed. Additionally, the annealing temperature can be 800°C to 900°C, and the annealing time can be 1.5 h to 2.5 h. Further, the hot isostatic pressing temperature can be 900°C to 950°C, the hot isostatic pressing pressure can be 100 MPa to 150 MPa, and the hot isostatic pressing time can be 1 h to 2 h. This can promote the complete grain boundary diffusion reaction of the as-cast composite coating and ensure the closure of pores and the full progress of interfacial chemical bonding in the as-cast composite coating.

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

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

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

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

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

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

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

[0134] S102. Ultrasonically cleaning the rough metal substrate to obtain a pretreated substrate.

[0135] In these embodiments, the metal substrate is sandblasted and then ultrasonically cleaned in sequence. By sandblasting, the surface of the metal substrate can be roughened (e.g., Ra = 3 μm), and then ultrasonic cleaning can remove residual debris and impurities such as grease on 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 in the ultrasonic cleaning stage.

[0137] Figure 3 Exemplarily shown is a schematic structural diagram of a PVD composite coating provided in Embodiment 1 of the present application;

[0138] Figure 4 Exemplarily shown is a schematic structural diagram of a PVD composite coating provided in Embodiment 4 of the present application;

[0139] Based on a general inventive concept, as Figure 3 and Figure 4 shown, the embodiments of the present application provide a PVD composite coating, and the composite coating is prepared by the method; the composite coating covers the surface of a metal substrate, the composite coating includes a plurality of rare-earth doped high-entropy alloy coatings and a plurality of composite ceramic coatings, 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 layer and the innermost layer; the composite ceramic coatings and the rare-earth doped high-entropy alloy coatings are connected and fixed through a treatment layer.

[0140] This composite coating is realized based on the above preparation method. For the specific steps of this preparation method, reference can be made to the above embodiments. Since this composite coating adopts some or all of the technical solutions of the above embodiments, it at least has all the beneficial effects brought by the technical solutions of the above embodiments, and will not be elaborated one by one here.

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

[0142] The following further elaborates the present application in conjunction with specific embodiments. For the experimental methods without specific conditions noted in the following embodiments, they are usually determined according to national standards / industry standards; if there are no corresponding national standards / industry standards, they are carried out according to general international standards, conventional conditions, or the conditions recommended by the manufacturer.

[0143] Embodiment 1

[0144] As Figure 2 shown, a preparation method of a PVD composite coating includes:

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

[0146] S102. Ultrasonically clean the rough metal substrate to obtain a pretreated substrate;

[0147] S2. Perform magnetron sputtering deposition on the surface of the pretreated substrate using a composite target containing rare-earth elements to obtain a first rare-earth doped high-entropy alloy coating;

[0148] S3. Perform multiple plasma sprayings on the surface of the first rare-earth doped high-entropy alloy coating using a composite oxide to obtain a first composite ceramic coating with a gradient content;

[0149] S4. Subject the first composite ceramic coating to laser texturing to form a honeycomb microstructure on the surface of the first composite ceramic coating, obtaining a first treated layer;

[0150] S5. Perform magnetron sputtering deposition on the surface of the first treated layer using a composite target containing rare-earth elements to obtain a second rare-earth doped high-entropy alloy coating;

[0151] S6. Perform multiple plasma sprayings on the surface of the second rare-earth doped high-entropy alloy coating using a composite oxide to obtain a second composite ceramic coating with a gradient content;

[0152] S7. Subject the second composite ceramic coating to laser texturing to form a honeycomb microstructure on the surface of the second composite ceramic coating, obtaining a second treated layer;

[0153] S8. Perform magnetron sputtering deposition on the surface of the second treated layer using a composite target containing rare-earth elements to obtain a rough composite coating containing a third rare-earth doped high-entropy alloy coating;

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

[0155] S902. Subject the annealed rough composite coating to hot isostatic pressing treatment to obtain a composite coating as shown in Figure 3 ;

[0156] Among them, the temperature of the annealing treatment is 850 °C, and the time of the annealing treatment is 2.0 h;

[0157] The temperature of the hot isostatic pressing treatment is 920 °C, the pressure of the hot isostatic pressing treatment is 130 MPa, and the time of the hot isostatic pressing treatment is 1.5 h; the composite target is AlCoCrFeNi-Y, and the composite oxide includes alumina, titanium oxide, and cerium oxide.

[0158] The pressure of the magnetron sputtering deposition is 0.5 Pa, the power density of the magnetron sputtering deposition is 3 W / cm 2 , the voltage of the magnetron sputtering deposition is -100 V, the temperature of the magnetron sputtering deposition is 300 °C, and the time of the magnetron sputtering deposition is 4 h.

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

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

[0161] The mass content of titanium oxide in the first composite ceramic coating shows a gradually increasing state distribution, and the difference between the mass contents of adjacent titanium oxides is 2% - 3%; specifically: the first composite ceramic coating includes four layers, and in the single-layer ceramic coating, the mass m1 of aluminum oxide and the mass m2 of titanium oxide successively satisfy the relationship: m1:m2 = 84:6, 82:8, 79:11, 76:14. The corresponding plasma spraying powers are 50kW, 48kW, 47kW, and 46kW in sequence, the plasma spraying voltages are 65V, 61V, 58V, and 56V in sequence, the plasma spraying powder feeding rates are 35g / min, 33g / min, 30g / min, and 27g / min in sequence, and the plasma spraying distances are 120mm, 100mm, 90mm, and 80mm in sequence.

[0162] The mass content of titanium oxide in the second composite ceramic coating shows a gradually decreasing state distribution, and the difference between the mass contents of adjacent titanium oxides is 2% - 3%; specifically: the second composite ceramic coating includes four layers, and in the single-layer ceramic coating, the mass m1 of aluminum oxide and the mass m2 of titanium oxide successively satisfy the relationship: m1:m2 = 76:14, 79:11, 82:8, 84:6. The corresponding plasma spraying powers are 46kW, 47kW, 48kW, and 50kW in sequence, the plasma spraying voltages are 65V, 61V, 58V, and 56V in sequence, the plasma spraying powder feeding rates are 27g / min, 30g / min, 33g / min, and 35g / min in sequence, and the plasma spraying distances are 80mm, 90mm, 100mm, and 120mm in sequence.

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

[0164] The mass content of rare earth elements in 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 2.0%.

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

[0166] The thickness h1 of the first composite ceramic coating and the thickness h2 of the second composite ceramic coating satisfy the relation: h1 + h2 = 50 μm; wherein, 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 aperture of a single honeycomb microstructure of the first treatment layer and the second treatment layer is 20 μm, and the depth of a single honeycomb microstructure of the first treatment layer and the second treatment layer 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] On the basis of the content disclosed in Example 1, the following further modifications are made:

[0171] The pressure of magnetron sputtering deposition is 0.3 Pa, the power density of magnetron sputtering deposition is 4 W / cm 2 , the voltage of magnetron sputtering deposition is -150 V, the temperature of magnetron sputtering deposition is 200 °C, and the time of magnetron sputtering deposition is 6.0 h.

[0172] Example 3

[0173] On the basis of the content disclosed in Example 1, the following further modifications are made:

[0174] The pressure of magnetron sputtering deposition is 0.8 Pa, the power density of magnetron sputtering deposition is 2 W / cm 2 , the voltage of magnetron sputtering deposition is -50 V, the temperature of magnetron sputtering deposition is 400 °C, and the time of magnetron sputtering deposition is 1.5 h.

[0175] Example 4

[0176] On the basis of the content disclosed in Example 1, the following further modifications are made:

[0177] As Figure 4As shown, the mass content of titanium oxide in the first composite ceramic coating shows a gradually increasing state distribution, and the difference between the mass contents of adjacent titanium oxides is 3% - 5%; specifically: the first composite ceramic coating includes three layers, and in the single-layer ceramic coating, the mass m1 of aluminum oxide and the mass m2 of titanium oxide successively satisfy the relationship: m1:m2 = 85:5, 80:10, 77:13. The corresponding plasma spraying powers are 50kW, 47kW, and 45kW in sequence, the plasma spraying voltages are 65V, 60V, and 55V in sequence, the plasma spraying powder feeding rates are 35g / min, 30g / min, and 25g / min in sequence, and the plasma spraying distances are 120mm, 100mm, and 80mm in sequence.

[0178] The mass content of titanium oxide in the second composite ceramic coating shows a gradually decreasing state distribution, and the difference between the mass contents of adjacent titanium oxides is 3% - 5%; specifically: the second composite ceramic coating includes three layers, and in the single-layer ceramic coating, the mass m1 of aluminum oxide and the mass m2 of titanium oxide successively satisfy the relationship: m1:m2 = 77:13, 80:10, 85:5. The corresponding plasma spraying powers are 45kW, 47kW, and 50kW in sequence, the plasma spraying voltages are 55V, 60V, and 65V in sequence, the plasma spraying powder feeding rates are 25g / min, 30g / min, and 35g / min in sequence, and the plasma spraying distances are 80mm, 100mm, and 120mm in sequence.

[0179] Example 5

[0180] On the basis of the content disclosed in Example 1, the following further modifications are made:

[0181] The mass content of rare earth elements in 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%.

[0182] Example 6

[0183] On the basis of the content disclosed in Example 1, the following further modifications are made:

[0184] The mass content of rare earth elements in 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 2.5%.

[0185] Example 7

[0186] On the basis of the content disclosed in Example 1, the following further modifications are made:

[0187] The pore diameter of a single honeycomb microstructure of the first treatment layer and the second treatment layer is 15μm.

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

[0189] Example 8

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

[0191] The aperture of a single honeycomb microstructure of the first processing layer and the second processing layer is 25 μm.

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

[0193] Example 9

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

[0195] The temperature of the annealing treatment is 800 °C, and the time of the annealing treatment is 2.5 h;

[0196] The temperature of the hot isostatic pressing treatment is 900 °C, the pressure of the hot isostatic pressing treatment is 150 MPa, and the time of the hot isostatic pressing treatment is 2 h.

[0197] Example 10

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

[0199] The temperature of the annealing treatment is 900 °C, and the time of the annealing treatment is 1.5 h;

[0200] The temperature of the hot isostatic pressing treatment is 950 °C, the pressure of the hot isostatic pressing treatment is 100 MPa, and the time of the hot isostatic pressing treatment is 1 h.

[0201] Comparative Example 1

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

[0203] Magnetron sputtering deposition is not carried out, that is, 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 relationship: h1 + h2 = 69 μm; wherein, 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] On the basis of the content disclosed in Example 1, the following further modifications are made:

[0207] Only one-step magnetron sputtering deposition and one-step multi-pass plasma spraying are carried out, that is, the composite coating has only one layer of the first rare earth-doped high-entropy alloy coating and one layer of the 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] On the basis of the content disclosed in Example 1, the following further modifications are made:

[0212] Only two-step magnetron sputtering deposition, one-step multi-pass plasma spraying and laser texturing are carried out, that is, the composite coating has only two layers of rare earth-doped high-entropy alloy coatings, two layers of 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 relationship: h1 + h2 = 56 μm; wherein, 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] On the basis of the content disclosed in Example 1, the following further modifications are made:

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

[0218] Comparative Example 5

[0219] On the basis of the content disclosed in Example 1, the following further modifications are made:

[0220] The mass content of titanium oxide in the first composite ceramic coating remains consistent; specifically: the first composite ceramic coating includes four layers, and in the single-layer ceramic coating, the mass m1 of aluminum oxide and the mass m2 of titanium oxide 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 includes four layers, and in a single-layer ceramic coating, the mass m1 of aluminum oxide and the mass m2 of titanium oxide sequentially satisfy the relational expression: m1:m2 = 80:10.

[0222] Comparative Example 6

[0223] On the basis of the content disclosed in Example 1, the following further modifications are made:

[0224] The pore diameter of a single honeycomb microstructure in the first treatment layer and the second treatment layer 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] On the basis of the content disclosed in Example 1, the following further modifications are made:

[0228] The pore diameter of a single honeycomb microstructure in the first treatment layer and the second treatment layer 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] Related experiments and effect data:

[0231] The composite coatings obtained in each of the examples and comparative examples were subjected to morphology analysis. The specific process was as follows: a scanning electron microscope and a backscattered diffraction probe were used to observe and analyze the grain morphology and crystal phase of the composite coatings on the surface or cross-section. The results showed that the grain distribution of each composite coating in the examples of the present application was uniform and the layering between grain boundaries was not obvious, while there were various defects in the comparative examples.

[0232] The composite coatings obtained in each example and comparative example were subjected to hardness testing and adhesion testing, and the results are shown in Table 1. Among them, for the hardness testing, referring to GB / T 7997-2014 "Test Method for Vickers Hardness of Cemented Carbide", a nanoindentation instrument was used to perform microhardness testing on the composite coatings. Then, based on Comparative Example 1, the Vickers hardness improvement rate of each example and comparative example was determined. The Vickers hardness improvement rate = (measured Vickers hardness - Vickers hardness of Comparative Example 1) / Vickers hardness of Comparative Example 1; for the adhesion, the film-substrate adhesion of the composite coatings was measured by the scratch method. The specific process 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 at which the coating cracked was used to characterize the strength of the film-substrate adhesion of the coating. The measurement parameters were: the total scratch length was 15 mm, the scratch speed was 3 mm / min; the pressure of the indenter was 0 N to 120 N; the loading speed was 333 mN / s. According to the acoustic signal of the coating cracking synchronously collected during the scratch loading test, the critical load, that is, the film-substrate adhesion, was determined by comparing the change in the friction force when the indenter passed over the substrate after the coating cracked.

[0233] Table 1 Results of the hardness and adhesion of the composite coatings obtained in each example and comparative example

[0234]

[0235] As can be seen from Table 1, a method for preparing a PVD composite coating provided by an embodiment of the present application. Through a series of process steps such as pre-treating a metal substrate, magnetron sputtering to deposit a rare-earth doped high-entropy alloy coating, plasma spraying to form a composite ceramic coating with a gradient content, laser texturing treatment, and alternating construction of multi-layer coatings, combined with carefully selected materials with a low coefficient of thermal expansion, the advantages of each process and material are fully utilized, so that the Vickers hardness HV of the composite coating reaches above 2000 and the adhesion reaches above 70 N. At the same time, the grain distribution of the composite coating is uniform and the stratification between grain boundaries is not obvious.

[0236] In addition, although the difference between Comparative Example 6 and each example is not significant, the pore diameter of the honeycomb microstructure used in Comparative Example 6 is small, requiring a relatively high laser texturing pulse energy and more precise parameter control, which requires higher equipment requirements and increases the equipment usage cost. In addition, although the Vickers hardness of Comparative Example 7 is not significantly different from that of each example, the adhesion of Comparative Example 7 is poor. Moreover, compared with Example 4 of the present application, the present application can achieve the same adhesion effect by using a composite ceramic coating with a three-layer structure, which indirectly shows that the honeycomb microstructure with a large pore diameter will deteriorate the adhesion.

[0237] In summary, a preparation method of a PVD composite coating provided by an embodiment of the present application. Through a series of process steps such as pre-treating a metal substrate, magnetron sputtering to deposit a rare-earth doped high-entropy alloy coating, plasma spraying to form a composite ceramic coating with a gradient content, laser texturing treatment, and alternately constructing multi-layer coatings, combined with carefully selected materials having a low coefficient of thermal expansion, the bonding strength, hardness, and strength of the composite coating can be significantly improved.

[0238] In addition, a preparation method of a PVD composite coating provided by an embodiment of the present application. The composite coating obtained by this preparation method can be widely used on the surfaces of cutting tools, lathe dies, and other metal parts to improve the surface mechanical properties of these metal parts.

[0239] In addition, a preparation method of a PVD composite coating provided by an embodiment of the present application. The composite coating obtained by this preparation method can also be used for aerospace high-temperature components or high-load cutting tool coatings.

[0240] The above are only specific embodiments of the present application, enabling those skilled in the art to understand or implement the present application. Various modifications to these embodiments will be obvious to those skilled in the art. The general principles defined in the present application can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to these embodiments shown in the present application, but will conform to the widest scope consistent with the principles and novel features claimed in the present application.

Claims

1. A method for preparing a PVD composite coating, the preparation method comprising: Pre-treating the metal substrate to obtain a pre-treated substrate; Using a composite target material containing a rare earth element to perform magnetron sputtering deposition on the surface of the pretreated substrate to obtain a first rare earth-doped high entropy alloy coating; Plasma spraying is performed multiple times on the surface of the first rare earth-doped high entropy alloy coating using a composite oxide to obtain a first composite ceramic coating with a gradient content; Laser texturing the first composite ceramic coating to form a honeycomb microstructure on the surface of the first composite ceramic coating to obtain a first treated layer; Using the composite target material containing rare earth elements to perform the magnetron sputtering deposition on the surface of the first treated layer to obtain a second rare earth-doped high entropy alloy coating; Using the composite oxide to perform the plasma spraying multiple times on the surface of the second rare earth-doped high entropy alloy coating to obtain a second composite ceramic coating with a gradient content; The second composite ceramic coating is subjected to the laser texturing to form a honeycomb microstructure on the surface of the second composite ceramic coating to obtain a second treated layer; Using the composite target material containing rare earth elements to perform the magnetron sputtering deposition on the surface of the second treated layer, to obtain a composite coating crude product containing a third rare earth-doped high entropy alloy coating; Post-processing the crude composite coating to obtain a composite coating; Wherein, the composite target material is AlCoCrFeNi-Y, and the composite oxide includes aluminum oxide, titanium oxide and cerium oxide.

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

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

4. The preparation method according to claim 1, wherein the mass m1 of the aluminum oxide, 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.

5. The preparation method according to claim 1, wherein 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% to 5%; and / or The mass content of titanium oxide in the second composite ceramic coating is distributed in a gradually decreasing state, and the difference between the mass content of two adjacent titanium oxides is 2% to 5%; and / or The mass content of rare earth elements in 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%.

6. The preparation method according to claim 1, wherein 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 are 5 μm to 10 μm respectively; and / or 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 The pore size of a single honeycomb microstructure of the first treatment layer and the second treatment layer is 15 μm to 25 μm, and the depth of a single honeycomb microstructure of the first treatment layer and the second treatment layer is 3 μm to 5 μm.

7. According to the preparation method of claim 1, the pulse energy of the laser texturing is 35μJ~45μJ, the repetition frequency of the laser texturing is 100kHz~500kHz, the scanning speed of the laser texturing is 100mm / s~1000mm / s, and the spot diameter of the laser texturing is 15μm~25μm.

8. The preparation method according to claim 1, wherein the crude composite coating is post-processed to obtain the composite coating, comprising the steps of: annealing the crude composite coating product to obtain an annealed crude composite coating product; The annealed composite coating crude product is subjected to hot isostatic pressing to obtain a composite coating; in, The temperature of the annealing treatment is 800°C to 900°C, and the time of the annealing treatment is 1.5h to 2.5h; The temperature of the hot isostatic pressing treatment is 900° C. to 950° C., the pressure of the hot isostatic pressing treatment is 100 MPa to 150 MPa, and the time of the hot isostatic pressing treatment is 1 h to 2 h.

9. The preparation method according to claim 1, wherein the metal substrate is pretreated to obtain a pretreated substrate, comprising the steps of: sandblasting the metal substrate to obtain a rough metal substrate; The rough metal substrate is ultrasonically cleaned to obtain a pretreated substrate.

10. A PVD composite coating, which is prepared by the method described in any one of claims 1 to 9; the composite coating covers the surface of a metal substrate, the composite coating 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 alternately arranged, 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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