A nano-multilayer gradient heterogeneous composite coating, its preparation method and application

Abstract

The present invention relates to the technical field of nano-multilayer composite coatings, and more specifically, to a nano-multilayer gradient heterogeneous composite coating, a preparation method thereof, and an application thereof. The nano-multilayer gradient heterogeneous composite coating includes an AlCrN bottom layer, an AlCrN / TiSiN nano-multilayer, an AlCrTiSiN high-entropy layer, and a TiSiN top layer arranged in sequence; wherein, the AlCrN / TiSiN nano-multilayer is composed of alternately arranged AlCrN sub-layers and TiSiN sub-layers, and is connected to the AlCrN bottom layer and the AlCrTiSiN high-entropy layer through the AlCrN sub-layers. The present invention uses four coatings with different hardnesses for composite, overcomes the defects of single-structure coatings, improves the properties such as the bonding force between the coating and the substrate, and has high hardness, film-substrate bonding force, and corrosion resistance, and has excellent corrosion resistance in products such as PVC injection molds.

Description

Technical Field

[0001] The present invention relates to the technical field of nano-multilayer composite coatings, and more specifically, to an AlCrN-AlCrN / TiSiN-AlCrTiSiN-TiSiN nano-multilayer gradient heterogeneous composite coating, a preparation method thereof, and an application thereof. Background Art

[0002] Due to its excellent flame retardancy and molding properties, PVC has been widely used in various covering products. However, when PVC is plasticized, it is easy to release strongly corrosive HCl gas, which seriously corrodes the mold, resulting in a short service life of the mold, reduced product quality, and reduced production efficiency.

[0003] In recent years, PVD nitride coatings have been widely used in hardware processing molds, cutting tools, etc. due to their high hardness, excellent thermal stability, and high-temperature oxidation resistance. However, single-structured coatings have various defects, resulting in a short service life. For example: for columnar crystal structure coatings, the bonding force is high, but the columnar crystal boundaries are fast diffusion channels for corrosive media, which can promote the penetration of corrosive media into the substrate and accelerate the corrosion and peeling of the coating; for nano-multilayer structures and nano-composite structures, the structure is dense, but the internal stress is large, and the coating thickness needs to be reasonably controlled, otherwise the coating will peel off; high-entropy coatings have high hardness, corrosion resistance, and low internal stress due to the high-entropy effect, lattice distortion effect, retarded diffusion effect, and "cocktail" effect, modulate the interface stress, improve the layer interface bonding behavior, and improve the coating bonding force. Previous studies have found that single-structured PVD coatings are difficult to meet the requirements of strong HCl corrosion resistance. In addition, there are high-density microparticles on the surface of the PVD coating during preparation. When the coating is thin, these microparticles penetrate through the entire coating, and the interface between the microparticles and the coating substrate is a diffusion channel for corrosive media, which is extremely harmful to the corrosion resistance of the coating. Therefore, thin coatings have low resistance to HCl corrosion. Summary of the Invention

[0004] The purpose of the present invention is to provide an AlCrN-AlCrN / TiSiN-AlCrTiSiN-TiSiN nano-multilayer gradient heterogeneous composite coating, a preparation method thereof, and an application thereof. By compounding four coatings with different hardnesses, the defects of single coatings are overcome. Through the design of four coating gradient structures, the properties such as the bonding force between the coating and the substrate are improved; by introducing a high-density layered interface, the penetration of corrosive media into the substrate is inhibited, and the corrosion resistance of the coating is improved; by regulating the coating thickness, the corrosion resistance of the coating is further improved. This gradient heterogeneous composite coating has high film-substrate bonding force and corrosion resistance, and has excellent corrosion resistance in products such as PVC injection molds.

[0005] To achieve the above purpose, the present invention provides the following solutions:

[0006] One of the technical solutions of the present invention: Provide an AlCrN-AlCrN / TiSiN-AlCrTiSiN-TiSiN nano-gradient heterogeneous coating, including an AlCrN bottom layer, an AlCrN / TiSiN nano-multilayer, an AlCrTiSiN high-entropy layer, and a TiSiN top layer arranged in sequence; wherein, the AlCrN / TiSiN nano-multilayer is composed of alternately arranged AlCrN sub-layers and TiSiN sub-layers, and is connected to the AlCrN bottom layer and the AlCrTiSiN high-entropy layer through the AlCrN sub-layers.

[0007] The present invention uses AlCrN with moderate corrosion resistance and high bonding strength as the bottom layer to improve the film-substrate bonding strength; the AlCrN / TiSiN nano-multilayer with both hardness and corrosion resistance is used as the second layer, and the AlCrN / TiSiN nano-multilayer is used to improve the coating density and inhibit the growth of penetrating microparticles, greatly reducing the internal growth defects of the coating, thereby improving the corrosion resistance of the coating; the AlCrTiSiN high-entropy coating with excellent corrosion resistance and toughness is used as the third layer to adjust the interface stress and improve the interlayer bonding strength of the coating. In addition, it can also increase the thickness of the coating; the surface is coated with a TiSiN coating with high hardness to improve the erosion resistance of the coating. By regulating the structure of each layer in the gradient heterogeneous composite coating, the coating has high hardness, film-substrate bonding strength, and corrosion resistance.

[0008] Furthermore, an epitaxial growth structure is maintained between the AlCrTiSiN high-entropy layer and the AlCrN sub-layer, so that the two layers have similar compositions and the same structures, and the interlayer bonding strength is high.

[0009] Furthermore, the thickness of the AlCrN bottom layer is 0.2 - 2.0 μm;

[0010] Furthermore, the thickness of the AlCrN / TiSiN nano-multilayer is 2.0 - 8.0 μm, and the single-layer thickness of the AlCrN sub-layer and the TiSiN sub-layer is 5 - 20 nm;

[0011] Furthermore, the thickness of the AlCrTiSiN high-entropy layer is 1.0 - 8.0 μm;

[0012] Furthermore, the thickness of the TiSiN top layer is 0.2 - 2.0 μm;

[0013] Furthermore, the total thickness of the AlCrN-AlCrN / TiSiN-AlCrTiSiN-TiSiN nano-gradient heterogeneous coating ranges from 3.4 to 20.0 μm.

[0014] Further, the thickness of the AlCrN bottom layer is 0.2 - 2.0 μm, the thickness of the AlCrN / TiSiN nano-multilayer is 2.0 - 8.0 μm, the thickness of the AlCrTiSiN high-entropy layer is 1.0 - 8.0 μm, and the thickness of the TiSiN top layer is 0.2 - 2.0 μm; the single-layer thickness of the AlCrN sub-layer and the TiSiN sub-layer is 5 - 20 nm.

[0015] Through multiple experiments, the present invention finds that the coating thickness will affect the bonding strength and HCl corrosion resistance of the composite coating. Specifically:

[0016] The AlCrN bottom layer has a high affinity with the substrate and high bonding strength;

[0017] The TiSiN top layer is a nano-composite structure, with a smooth surface and a dense structure, and strong corrosion resistance.

[0018] A certain thickness of the AlCrN / TiSiN nano-multilayer can reduce the internal growth defects (such as microparticles and pores) in the AlCrN-AlCrN / TiSiN-AlCrTiSiN-TiSiN nano-gradient heterogeneous coating and improve the coating density. However, if the AlCrN / TiSiN nano-multilayer is too thick, the coating is prone to peeling. Therefore, its thickness needs to be reasonably controlled. In addition, the alternating sequence of the AlCrN sub-layer and the TiSiN sub-layer in the AlCrN / TiSiN nano-multilayer, as well as the fact that the starting and ending sub-layers are AlCrN, will further improve the corrosion resistance of the AlCrN-AlCrN / TiSiN-AlCrTiSiN-TiSiN of the present invention.

[0019] The thickness of the AlCrTiSiN high-entropy layer will affect the corrosion resistance of the AlCrN-AlCrN / TiSiN-AlCrTiSiN-TiSiN nano-gradient heterogeneous composite coating. If the thickness of the AlCrTiSiN high-entropy layer is too large (greater than 3 μm), it will increase the internal stress of the nano-gradient heterogeneous composite coating, thereby increasing the brittleness of the coating; while if the thickness is too small (less than 1.0 μm), the improvement effect on the corrosion resistance of the gradient heterogeneous composite coating is not obvious. That is, if the thickness of the AlCrTiSiN high-entropy layer is not appropriate, the corrosion resistance of the coating cannot be effectively improved.

[0020] Further, the AlCrN bottom layer is a columnar crystal structure; the AlCrTiSiN high-entropy layer is a single-phase solid solution structure of columnar crystals; the TiSiN top layer is a nano-composite structure.

[0021] The second technical solution of the present invention is a method for preparing the above-mentioned nano-gradient heterogeneous composite coating, including the following steps:

[0022] Under a nitrogen atmosphere, an AlCrN bottom layer is physically vapor deposited on the substrate surface using an AlCr target;

[0023] Under a nitrogen atmosphere, an AlCrN sub-layer and a TiSiN sub-layer are alternately physically vapor deposited on the surface of the AlCrN bottom layer using an AlCr target and a TiSi target, thereby obtaining an AlCrN / TiSiN nano-multilayer;

[0024] Under a nitrogen atmosphere, an AlCrTiSiN high-entropy coating is physically vapor deposited on the surface of the AlCrN / TiSiN nano-multilayer using an AlCrTiSi target;

[0025] Under a nitrogen atmosphere, a TiSiN top layer is physically vapor deposited on the surface of the AlCrTiSiN high-entropy coating using a TiSi target.

[0026] Furthermore, the substrate is a steel substrate, aluminum alloy, titanium alloy or cemented carbide; the substrate is ultrasonically degreased, defatted, cleaned and dried before use.

[0027] Furthermore, an AlCrN bottom layer is physically vapor deposited on the substrate surface using an arc ion plating equipment, and the specific parameters include: controlling the AlCr target current to be 120 - 200 A, the nitrogen flow rate to be 300 - 800 sccm, applying a substrate bias voltage of -40 to -100 V, controlling the rotation speed of the workpiece turntable in the furnace to be 2.0 - 5.0 rpm, and depositing on the substrate surface at 400 - 550 °C for 10 - 60 min.

[0028] Furthermore, an AlCrN / TiSiN nano-multilayer is prepared using an arc ion plating equipment, and the specific parameters include: controlling the currents of both the AlCr target and the TiSi target to be 120 - 200 A, introducing nitrogen at 500 - 800 sccm, applying a substrate bias voltage of -40 to -100 V, controlling the rotation speed of the workpiece turntable in the furnace to be 2.0 - 5.0 rpm, and alternately depositing an AlCrN sub-layer and a TiSiN sub-layer on the surface of the AlCrN bottom layer using the AlCr target and the TiSi target at 400 - 550 °C, with the single-layer deposition time of the sub-layer being 6 - 15 s and the total deposition time being 40 - 150 min.

[0029] Furthermore, an AlCrTiSiN high-entropy coating is prepared using an arc ion plating equipment, and the specific parameters include: controlling the AlCrTiSi target current to be 120 - 200 A, introducing nitrogen at 500 - 800 sccm, applying a substrate bias voltage of -40 to -100 V, controlling the rotation speed of the workpiece turntable in the furnace to be 2.0 - 5.0 rpm, and depositing an AlCrTiSiN high-entropy layer on the surface of the AlCrN / TiSiN nano-multilayer at 400 - 550 °C for 20 - 60 min.

[0030] Further, an arc ion plating equipment is used to prepare the TiSiN top layer. The specific parameters include: controlling the TiSi target current to be 120 - 200 A, introducing nitrogen at 500 - 800 sccm, applying a substrate bias voltage of -40 to -100 V, controlling the rotation speed of the workpiece turntable in the furnace to be 2.0 - 5.0 rpm, depositing the TiSiN top layer on the surface of the AlCrTiSiN high-entropy layer at 400 - 550 °C, and the deposition time is 10 - 30 min.

[0031] In the third technical solution of the present invention, the above-mentioned nano-multilayer gradient heterogeneous composite coating is used as an injection mold coating and a corrosion-resistant spare parts coating.

[0032] The present invention discloses the following technical effects:

[0033] The present invention uses AlCrN with moderate corrosion resistance and high bonding strength as the bottom layer, and the AlCrN / TiSiN nano-multilayer with both hardness and corrosion resistance. The AlCrTiSiN high-entropy coating with low corrosion-resistant internal stress is used to adjust the interface stress between the nano-multilayer and the TiSiN layer, improve the interlayer bonding strength, improve the corrosion resistance of the coating, and can effectively increase the thickness of the coating; the hardness and erosion resistance of the coating are improved through the TiSiN coating. Through the above-mentioned composite design of multiple structures, an AlCrN-AlCrN / TiSiN-AlCrTiSiN-TiSiN gradient heterogeneous composite coating with high bonding strength and excellent corrosion resistance is finally obtained.

[0034] The common methods of physical vapor deposition currently include arc ion plating, evaporation plating, magnetron sputtering, and high-power pulsed magnetron sputtering. The ionization rates of evaporation plating and magnetron sputtering are low, and the bonding strength between the coating and the substrate is poor; the ionization rate of high-power pulsed is high, but the deposition efficiency is extremely low. In comparison, arc ion plating has a high ionization rate and deposition efficiency, and the coating is dense and has a high bonding strength. In the present invention, an AlCrN bottom layer, an intermediate layer composed of AlCrN / TiSiN and AlCrTiSiN, and a TiSiN surface layer are sequentially deposited on the substrate surface through an arc ion plating equipment. The nano-multilayer gradient composite coating prepared by this method has excellent corrosion resistance. Description of the Drawings

[0035] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required to be used in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0036] Figure 1 It is a schematic cross-sectional structure diagram of the AlCrN-AlCrN / TiSiN-AlCrTiSiN-TiSiN gradient heterogeneous composite coating in Embodiment 1.

[0037] Figure 2 The physical diagram of the mold with the AlCrN-AlCrN / TiSiN-AlCrTiSiN-TiSiN gradient heterogeneous composite coating prepared by the method of Example 1.

[0038] Figure 3 The physical diagram of the mold with the AlCrN-AlCrN / TiSiN-AlCrTiSiN-TiSiN gradient heterogeneous composite coating prepared by the method of Example 1 after serving 600,000 die-casting cycles.

[0039] Figure 4 The physical diagram of the mold with the AlCrN-AlCrN / TiSiN-AlCrTiSiN gradient heterogeneous composite coating prepared by the method of Comparative Example 6.

[0040] Figure 5 The physical diagram of the mold with the AlCrN-AlCrN / TiSiN-AlCrTiSiN gradient heterogeneous composite coating prepared by the method of Comparative Example 6 after serving 98,000 die-casting cycles.

[0041] Figure 6 The TEM image of the AlCrN / TiSiN nano-multilayer structure prepared in Example 1. Detailed implementation manners

[0042] Now, various exemplary implementation manners of the present invention will be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, characteristics, and implementation schemes of the present invention.

[0043] It should be understood that the terms described in the present invention are only for describing specific implementation manners and are not used to limit the present invention. Additionally, for the numerical ranges in the present invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any intermediate value within any stated value or stated range, as well as each smaller range between any other stated value or intermediate value within the stated range, is also included in the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0044] Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the present invention pertains. Although the present invention only describes preferred methods and materials, any methods and materials similar or equivalent to those described herein can also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials related to the documents. In case of conflict with any incorporated document, the content of this specification shall prevail.

[0045] Without departing from the scope or spirit of the present invention, various modifications and variations to the specific embodiments of the description of the present invention will be obvious to those skilled in the art. Other embodiments obtained from the description of the present invention will be obvious to those skilled in the art. The description and examples of the present invention are merely exemplary.

[0046] Regarding the terms "comprising", "including", "having", "containing", etc. used herein, they are all open-ended terms, meaning including but not limited to.

[0047] All the target materials used in the following examples of the present invention are commercially available products. Specifically: the AlCr target is an Al70Cr30 target (70 at.% Al, 30 at.% Cr); the TiSi target is a Ti85Si15 target; the AlCrTiSi target is an Al35Cr20Ti30Si15 target.

[0048] Example 1

[0049] This example provides an AlCrN - AlCrN / TiSiN - AlCrTiSiN - TiSiN gradient heterogeneous composite coating, including an AlCrN layer, an AlCrN / TiSiN layer, an AlCrTiSiN layer, and a TiSiN layer connected in sequence. Among them, the AlCrN layer is the bottom layer, and the bottom layer is connected to S136 die steel (commercially available).

[0050] A preparation method for an AlCrN - AlCrN / TiSiN - AlCrTiSiN - TiSiN gradient heterogeneous composite coating includes the following steps:

[0051] S1: Ultrasonically degrease, defat, clean, and dry the substrate;

[0052] S2: Using an arc ion plating device, control the current of the AlCr target to be 160 A, the nitrogen flow rate to be 500 sccm, apply a substrate bias voltage of -40 V, control the rotation speed of the workpiece turntable in the furnace to be 3.5 rpm, and deposit on the substrate surface at 450 °C for 20 min to obtain the AlCrN bottom layer with a thickness of 0.4 μm;

[0053] S3: Control the currents of the AlCr target and the TiSi target to be both 160 A, introduce nitrogen at 600 sccm, apply a substrate bias voltage of -60 V, with a deposition time of 120 min. Control the rotation speed of the workpiece turntable in the furnace to be 3.5 rpm. At 450 °C, alternately deposit AlCrN sub-layers and TiSiN sub-layers on the surface of the AlCrN bottom layer using the AlCr target and the TiSi target successively to form an AlCrN / TiSiN layer with a thickness of 6 μm, and the thickness of each single sub-layer is 8 nm. Specifically, first deposit an AlCrN sub-layer with a thickness of 8 nm using the AlCr target, then deposit a TiSiN sub-layer with a thickness of 8 nm using the TiSi target, and alternate the depositions. Finally, deposit an AlCrN sub-layer with a thickness of 8 nm using the AlCr target for the last time. Thus, an AlCrN-AlCrN / TiSiN layer is obtained;

[0054] S4: Control the current of the AlCrTiSi target to be 160 A, introduce nitrogen at 600 sccm, apply a substrate bias voltage of -60 V, with a deposition time of 60 min. Control the rotation speed of the workpiece turntable in the furnace to be 3.5 rpm. At 450 °C, deposit an AlCrTiSiN high-entropy layer on the AlCrN-AlCrN / TiSiN layer, and its thickness is 3.0 μm. Thus, an AlCrN-AlCrN / TiSiN-AlCrTiSiN layer is obtained;

[0055] S5: Control the current of the TiSi target to be 160 A, introduce nitrogen at 600 sccm, apply a substrate bias voltage of -60 V, with a deposition time of 20 min. Control the rotation speed of the workpiece turntable in the furnace to be 3.5 rpm. At 450 °C, deposit a TiSiN high-entropy layer on the AlCrN-AlCrN / TiSiN-AlCrTiSiN layer, and its thickness is 1.0 μm. Thus, an AlCrN-AlCrN / TiSiN-AlCrTiSiN-TiSiN heterogeneous composite coating is obtained, and its thickness is 10.4 μm, and the structure is as Figure 1 shown.

[0056] Examples 2 to 6

[0057] Examples 2 to 6 provide different AlCrN-AlCrN / TiSiN-AlCrTiSiN-TiSiN nano-multilayer gradient composite coatings, each of which includes AlCrN, AlCrN / TiSiN, AlCrTiSiN, and TiSiN layers connected in sequence. Among them, the AlCrN layer is the bottom layer, and the bottom layer is connected to the substrate. The difference from Example 1 is that the parameters during the preparation of each layer are different, and the specific parameters of Examples 2 - 6 are shown in Tables 1 - 5.

[0058] Table 1 Relevant experimental parameters for preparing the AlCrN bottom layer

[0059]

[0060] Table 2 Relevant experimental parameters for preparing AlCrN / TiSiN nanomultilayers in Examples 2 - 6

[0061]

[0062]

[0063] Table 3 Relevant experimental parameters for preparing AlCrTiSiN high - entropy layers in Examples 2 - 6

[0064]

[0065] Table 4 Relevant experimental parameters for preparing TiSiN top layers in Examples 2 - 6

[0066]

[0067] Table 5 Coating thickness of AlCrN - AlCrN / TiSiN - AlCrTiSiN - TiSiN nanomultilayer gradient composite coatings in Examples 2 - 6

[0068]

[0069] Example 7

[0070] Same as Example 1, except that S2 and S3 are swapped.

[0071] Example 8

[0072] Same as Example 1, except that S2 and S4 are swapped.

[0073] Example 9

[0074] Same as Example 1, except that S3 and S4 are swapped.

[0075] Example 10

[0076] Same as Example 1, except that S3 and S5 are swapped.

[0077] Example 11

[0078] Same as Example 1, except that S4 and S5 are swapped.

[0079] Example 12

[0080] Same as Example 1, except that S2 and S5 are swapped.

[0081] Comparative Example 1

[0082] This comparative example provides an AlCrN layer, and its preparation method includes the following steps:

[0083] S1: Ultrasonically degrease, defat, clean, and dry the S136 die steel;

[0084] S2: Use an arc ion plating equipment, control the AlCr target current to be 160 A, introduce nitrogen at 500 sccm, apply a substrate bias voltage of -40 V, control the rotation speed of the workpiece turntable in the furnace to be 3.5 rpm, and deposit on the substrate surface at 450 °C for 20 min to obtain an AlCrN layer with a thickness of 0.4 μm.

[0085] Comparative Example 2

[0086] This comparative example provides an AlCrN / TiSiN nanomultilayer, and its preparation method includes the following steps:

[0087] S1: Ultrasonically degrease, defat, clean, and dry the S136 die steel;

[0088] S2: Use an arc ion plating equipment, control the currents of both the AlCr target and the TiSi target to be 160 A, introduce nitrogen at 600 sccm, apply a substrate bias voltage of -60 V, control the rotation speed of the workpiece turntable in the furnace to be 3.5 rpm, and alternately deposit on the substrate surface at 450 °C for 2 h using the AlCr target and the TiSi target to obtain an AlCrN / TiSiN nanomultilayer with a thickness of 6.0 μm. Specifically, first deposit an AlCrN sublayer with a thickness of 8 nm using the AlCr target, then deposit a TiSiN sublayer with a thickness of 2.5 nm using the TiSi target, deposit alternately, and finally deposit an AlCrN sublayer with a thickness of 8 nm using the AlCr target for the last time.

[0089] Comparative Example 3

[0090] This comparative example provides an AlCrTiSiN layer, and its preparation method includes the following steps:

[0091] S1: Ultrasonically degrease, defat, clean, and dry the S136 die steel;

[0092] S2: Use an arc ion plating equipment, control the AlCrTiSi target current to be 160 A, introduce nitrogen at 600 sccm, apply a substrate bias voltage of -60 V, control the rotation speed of the workpiece turntable in the furnace to be 3.5 rpm, and deposit on the substrate surface at 450 °C for 60 min to obtain an AlCrTiSiN layer with a thickness of 3.0 μm.

[0093] Comparative Example 4

[0094] This comparative example provides a TiSiN layer, and its preparation method includes the following steps:

[0095] S1: Ultrasonically degrease, defat, clean, and dry the S136 die steel;

[0096] S2: Use an arc ion plating equipment, control the TiSi target current to be 145 A, introduce nitrogen at 500 sccm, apply a substrate bias voltage of -60 V, control the rotation speed of the workpiece turntable in the furnace to be 3.5 rpm, and deposit on the substrate surface at 450 °C for 30 min to obtain an AlCrTiSiN layer with a thickness of 1.0 μm.

[0097] Comparative Example 5

[0098] This comparative example provides an AlCrN - AlCrN / TiSiN layer, including a sequentially connected AlCrN bottom layer and an AlCrN / TiSiN nano - multilayer. Its preparation method includes the following steps:

[0099] S1: Perform ultrasonic degreasing, defatting, cleaning, and drying on the S136 die steel.

[0100] S2: Use an arc ion plating equipment, control the AlCr target current to be 160 A, introduce nitrogen at 500 sccm, apply a substrate bias voltage of -40 V, control the rotation speed of the workpiece turntable in the furnace to be 3.5 rpm, and deposit on the surface of the S136 die steel at 420 °C for 20 min to obtain an AlCrN layer with a thickness of 0.4 μm.

[0101] S3: Control both the AlCr target and the TiSi target currents to be 160 A, introduce nitrogen at 600 sccm, apply a substrate bias voltage of -60 V, control the rotation speed of the workpiece turntable in the furnace to be 3.5 rpm, and alternately deposit on the AlCrN layer using the AlCr target and the TiSi target at 450 °C for 120 min to obtain an AlCrN / TiSiN nano - multilayer with a thickness of 6 μm. Thus, an AlCrN - AlCrN / TiSiN layer with a thickness of 6.4 μm is obtained. Specifically, first deposit an AlCrN sub - layer with a thickness of 8 nm using the AlCr target, then deposit a TiSiN sub - layer with a thickness of 2.5 nm using the TiSi target, deposit alternately, and finally deposit an AlCrN sub - layer with a thickness of 8 nm using the AlCr target. Thus, an AlCrN - AlCrN / TiSiN layer is obtained.

[0102] Comparative Example 6

[0103] This comparative example provides an AlCrN - AlCrN / TiSiN - AlCrTiSiN layer, including a sequentially connected AlCrN bottom layer, an AlCrN / TiSiN nano - multilayer, and an AlCrTiSiN high - entropy layer. Its preparation method includes the following steps:

[0104] S1: Perform ultrasonic degreasing, defatting, cleaning, and drying on the S136 die steel.

[0105] S2: Use an arc ion plating equipment to control the AlCr target current at 160 A, introduce nitrogen at 500 sccm, apply a substrate bias voltage of -40 V, control the rotation speed of the workpiece turntable in the furnace at 3.5 rpm, and deposit for 20 min on the surface of S136 die steel at 420 °C to obtain an AlCrN layer with a thickness of 0.4 μm;

[0106] S3: Control both the AlCr target and TiSi target currents at 160 A, introduce nitrogen at 600 sccm, apply a substrate bias voltage of -60 V, control the rotation speed of the workpiece turntable in the furnace at 3.5 rpm, and alternately deposit on the AlCrN layer using the AlCr target and TiSi target for 120 min at 450 °C to obtain an AlCrN / TiSiN nanomultilayer with a thickness of 6 μm; Thus, an AlCrN-AlCrN / TiSiN layer with a thickness of 6.4 μm is obtained. Specifically, first deposit an AlCrN sublayer with a thickness of 8 nm using the AlCr target, then deposit a TiSiN sublayer with a thickness of 2.5 nm using the TiSi target, deposit alternately, and finally deposit an AlCrN sublayer with a thickness of 8 nm using the AlCr target. Thus, an AlCrN-AlCrN / TiSiN layer is obtained;

[0107] S4: Control the AlCrTiSi target current at 160 A, introduce nitrogen at 600 sccm, apply a substrate bias voltage of -60 V, deposit for 60 min, control the rotation speed of the workpiece turntable in the furnace at 3.5 rpm, and deposit an AlCrTiSiN high-entropy layer with a thickness of 3.0 μm on the AlCrN-AlCrN / TiSiN layer at 450 °C. Thus, an AlCrN-AlCrN / TiSiN-AlCrTiSiN layer is obtained. Its total thickness is 9.4 μm.

[0108] Comparative Example 7

[0109] This comparative example provides an AlCrN-AlCrN / TiSiN-TiSiN layer, including an AlCrN bottom layer, an AlCrN / TiSiN nanomultilayer, and a TiSiN layer connected in sequence. Its preparation method includes the following steps:

[0110] S1: Perform ultrasonic degreasing, degreasing, cleaning, and drying on S136 die steel;

[0111] S2: Use an arc ion plating equipment to control the AlCr target current at 160 A, introduce nitrogen at 500 sccm, apply a substrate bias voltage of -40 V, control the rotation speed of the workpiece turntable in the furnace at 3.5 rpm, and deposit for 20 min on the surface of S136 die steel at 420 °C to obtain an AlCrN layer with a thickness of 0.4 μm;

[0112] S3: Control the currents of both the AlCr target and the TiSi target to be 160 A, introduce nitrogen at 600 sccm, apply a substrate bias voltage of -60 V, control the rotation speed of the workpiece turntable in the furnace to be 3.5 rpm, and alternately deposit for 120 min at 450 °C using the AlCr target and the TiSi target on the AlCrN layer to obtain an AlCrN / TiSiN nano-multilayer with a thickness of 6.0 μm. Specifically, first deposit an AlCrN sub-layer with a thickness of 8 nm using the AlCr target, then deposit a TiSiN sub-layer with a thickness of 2.5 nm using the TiSi target, deposit alternately, and finally deposit an AlCrN sub-layer with a thickness of 8 nm using the AlCr target. Thus, an AlCrN-AlCrN / TiSiN layer is obtained;

[0113] S4: Control the current of the TiSi target to be 160 A, introduce nitrogen at 500 sccm, apply a substrate bias voltage of -60 V, deposit for 30 min, control the rotation speed of the workpiece turntable in the furnace to be 3.5 rpm, and deposit a TiSiN layer with a thickness of 1.5 μm at 450 °C on the AlCrN-AlCrN / TiSiN layer. Thus, an AlCrN-AlCrN / TiSiN-TiSiN layer is obtained. Its total thickness is 7.9 μm.

[0114] Comparative Example 8

[0115] This comparative example provides an AlCrN / TiSiN-AlCrTiSiN-TiSiN layer, including an AlCrN / TiSiN nano-multilayer, an AlCrTiSiN high-entropy layer, and a TiSiN layer connected in sequence. Its preparation method includes the following steps:

[0116] S1: Perform ultrasonic degreasing, defatting, cleaning, and drying on the S136 die steel;

[0117] S2: Control the currents of both the AlCr target and the TiSi target to be 160 A, introduce nitrogen at 600 sccm, apply a substrate bias voltage of -60 V, control the rotation speed of the workpiece turntable in the furnace to be 3.5 rpm, and alternately deposit for 120 min at 450 °C using the AlCr target and the TiSi target on the substrate to obtain an AlCrN / TiSiN nano-multilayer with a thickness of 6.0 μm. Specifically, first deposit an AlCrN sub-layer with a thickness of 8 nm using the AlCr target, then deposit a TiSiN sub-layer with a thickness of 2.5 nm using the TiSi target, deposit alternately, and finally deposit an AlCrN sub-layer with a thickness of 8 nm using the AlCr target;

[0118] S3: Control the AlCrTiSi target current to 160 A, introduce nitrogen at 600 sccm, apply a substrate bias voltage of -60 V, deposit for 30 min, control the rotation speed of the workpiece turntable in the furnace to 3.5 rpm, and deposit an AlCrTiSiN layer on the AlCrN / TiSiN layer at 450 °C, with a thickness of 1.5 μm. Thus, an AlCrN / TiSiN-AlCrTiSiN layer is obtained, with a total thickness of 7.5 μm;

[0119] S4: Control the TiSi target current to 160 A, introduce nitrogen at 600 sccm, apply a substrate bias voltage of -60 V, deposit for 20 min, control the rotation speed of the workpiece turntable in the furnace to 3.5 rpm, and deposit a TiSiN layer on the AlCrN / TiSiN-AlCrTiSiN layer at 450 °C, with a thickness of 1.0 μm. Thus, an AlCrN / TiSiN-AlCrTiSiN-TiSiN hetero-composite coating is obtained, with a thickness of 8.5 μm.

[0120] Comparative Example 9

[0121] This comparative example provides an AlCrN-AlCrTiSiN-TiSiN layer, including an AlCrN layer, an AlCrTiSiN high-entropy layer, and a TiSiN layer connected in sequence. Its preparation method includes the following steps:

[0122] S1: Perform ultrasonic degreasing, defatting, cleaning, and drying on the S136 die steel;

[0123] S2: Control the AlCr target current to 160 A, introduce nitrogen at 500 sccm, apply a substrate bias voltage of -40 V, control the rotation speed of the workpiece turntable in the furnace to 3.5 rpm, and deposit AlCr for 20 min at 450 °C to obtain an AlCrN layer, with a thickness of 0.4 μm;

[0124] S3: Control the AlCrTiSi target current to 160 A, introduce nitrogen at 600 sccm, apply a substrate bias voltage of -60 V, deposit for 30 min, control the rotation speed of the workpiece turntable in the furnace to 3.5 rpm, and deposit an AlCrTiSiN layer on the AlCrN layer at 450 °C, with a thickness of 1.5 μm. Thus, an AlCrN-AlCrTiSiN layer is obtained, with a total thickness of 1.35 μm;

[0125] S4: Control the TiSi target current to 160 A, introduce nitrogen at 600 sccm, apply a substrate bias voltage of -60 V, deposit for 20 min, control the rotation speed of the workpiece turntable in the furnace to 3.5 rpm, and deposit the TiSiN layer on the AlCrN-AlCrTiSiN layer at 450 °C, with a thickness of 1.0 μm. Thus, the AlCrN-AlCrTiSiN-TiSiN hetero-composite coating is obtained, with a thickness of 2.9 μm.

[0126] Test Example

[0127] The following methods were used to test the performance of the coatings in the examples and comparative examples, and the results are shown in Table 6-7:

[0128] 1. Use a multi-functional scratch tester to test the adhesion between the coating and the substrate, with a test load of 0 - 120 N;

[0129] 2. Use an electrochemical workstation to measure the corrosion potential of each coating in a 10 vol.% HCl aqueous solution;

[0130] 3. Use the coatings of Example 1 and Comparative Example 6 for ABS + 40% PVC mixed injection molding processing. When visible pits appear on the surface of the injection-molded product, the coating mold is determined to fail.

[0131] Table 6 Performance Results of the Composite Coatings in Examples 1 - 12

[0132]

[0133]

[0134] The layer thicknesses of Examples 7 - 12 are the same as that of Example 1, but the order is different.

[0135] Table 7 Performance Test Results of the Coatings in Example 1 and Comparative Examples 1 - 9

[0136]

[0137] As can be seen from Table 6 and Table 7, the bonding strength between the coatings and the substrate in Examples 1-6 of the present invention ranges from 76 to 120 N, and the corrosion potential ranges from -0.02 to 0.18 V. Compared with Examples 1, Comparative Examples 1-9 did not achieve the simultaneous improvement of the substrate bonding strength and corrosion resistance. When comparing Example 1 with Examples 7-12, under the same preparation parameters, only the coating sequence was changed, making the bonding strength and corrosion resistance of the product in Example 1 better. Combining with the experimental results of omitting a certain coating in Comparative Examples 6-9, it shows that the structure and composition of the coatings of the present invention have a significant impact on the product performance; in addition, when using a single AlCrN / TiSiN coating, AlCrTiSiN coating or TiSiN coating, although the coating has better bonding strength, the corrosion resistance effect is not good; therefore, the coating sequence of AlCrN-AlCrN / TiSiN-AlCrTiSiN-TiSiN of the present invention is the optimal combination. By matching the structures of four different components of the AlCrN bottom layer, AlCrN / TiSiN nanomultilayer, AlCrTiSiN high-entropy layer and TiSiN nanocomposite layer, the present invention can effectively improve the corrosion resistance and bonding strength of the coating.

[0138] When processing by mixing injection molding of ABS + 40% PVC, the service life of the mold in Example 1 reached 600,000 molding cycles ( Figure 3 ), and the coating on the mold surface still existed. For the mold in Comparative Example 6, the service life was less than 100,000 molding cycles, the coating on the mold surface had peeled off, and there were high-density pitting defects on the product surface, and the coated mold failed ( Figure 5 ).

[0139] The above-described embodiments are only used to describe the preferred embodiments of the present invention, and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, various deformations and improvements made by those of ordinary skill in the art to the technical solutions of the present invention shall fall within the protection scope determined by the claims of the present invention.

Claims

1. A preparation method of a nano multi-layer gradient heterogeneous corrosion-resistant composite coating, characterized in that the nano multi-layer gradient heterogeneous corrosion-resistant composite coating includes an AlCrN bottom layer, an AlCrN / TiSiN nano multi-layer, an AlCrTiSiN high-entropy layer, and a TiSiN top layer arranged in sequence; wherein, the AlCrN / TiSiN nano multi-layer is composed of alternately arranged AlCrN sub-layers and TiSiN sub-layers, and is connected to the AlCrN bottom layer and the AlCrTiSiN high-entropy layer through the AlCrN sub-layers; the thickness of the AlCrN bottom layer is 0.2 - 2.0 μm; the thickness of the AlCrN / TiSiN nano multi-layer is 2.0 - 8.0 μm; the thickness of the AlCrTiSiN high-entropy layer is 1.0 - 8.0 μm; the thickness of the TiSiN top layer is 0.2 - 2.0 μm; the single-layer thickness of the AlCrN sub-layers and TiSiN sub-layers is 5 - 20 nm; the AlCrN bottom layer has a columnar crystal structure; the AlCrTiSiN high-entropy layer has a single-phase solid solution structure of columnar crystals; the TiSiN top layer has a nano composite structure; the raw material for preparing the AlCrN bottom layer is an Al70Cr30 target; the raw materials for preparing the AlCrN / TiSiN nano multi-layer are an Al70Cr30 target and a Ti85Si15 target; the raw material for preparing the AlCrTiSiN high-entropy layer is an Al35Cr20Ti30Si15 target; the raw material for preparing the TiSiN top layer is a Ti85Si15 target; the preparation method includes the following steps: Under a nitrogen atmosphere, physically vapor deposit the AlCrN bottom layer on the substrate surface using an Al70Cr30 target; Under a nitrogen atmosphere, alternately physically vapor deposit AlCrN sub-layers and TiSiN sub-layers on the surface of the AlCrN bottom layer using an Al70Cr30 target and a Ti85Si15 target to obtain the AlCrN / TiSiN nano multi-layer; Under a nitrogen atmosphere, physically vapor deposit the AlCrTiSiN high-entropy layer on the surface of the AlCrN / TiSiN nano multi-layer using an Al35Cr20Ti30Si15 target; Under a nitrogen atmosphere, physically vapor deposit the TiSiN top layer on the surface of the AlCrTiSiN high-entropy layer using a Ti85Si15 target.

2. The preparation method of the nano-multilayer gradient heterogeneous corrosion-resistant composite coating according to claim 1, characterized in that, The substrate is a steel substrate, aluminum alloy, titanium alloy or cemented carbide; the substrate is ultrasonically degreased, defatted, cleaned and dried before use.

3. The preparation method of the nano-multilayer gradient heterogeneous corrosion-resistant composite coating according to claim 1, wherein, Use an arc ion plating equipment to physically vapor deposit the AlCrN bottom layer on the substrate surface. The specific parameters include: controlling the current of the Al70Cr30 target to be 120 - 200 A, the nitrogen flow rate to be 300 - 800 sccm, applying a substrate bias voltage of -40 - -100 V, controlling the rotation speed of the workpiece turntable in the furnace to be 2.0 - 5.0 rpm, and depositing on the substrate surface at 400 - 550 °C for 10 - 60 min.

4. The preparation method of the nano-multilayer gradient heterogeneous corrosion-resistant composite coating according to claim 1, wherein, Prepare AlCrN / TiSiN nanomultilayers using an arc ion plating equipment. The specific parameters include: controlling the currents of both the Al70Cr30 target and the Ti85Si15 target to be 120 - 200 A, introducing nitrogen at 500 - 800 sccm, applying a substrate bias voltage of -40 to -100 V, controlling the rotation speed of the workpiece turntable in the furnace to be 2.0 - 5.0 rpm, and alternately depositing AlCrN sublayers and TiSiN sublayers on the surface of the AlCrN bottom layer using the Al70Cr30 target and the Ti85Si15 target at 400 - 550 °C. The single-layer deposition time of the sublayers is 6 - 15 s, and the total deposition time is 40 - 150 min.

5. The preparation method of the nano-multilayer gradient heterogeneous corrosion-resistant composite coating according to claim 1, characterized in that, Prepare the AlCrTiSiN high-entropy layer using an arc ion plating equipment. The specific parameters include: controlling the current of the Al35Cr20Ti30Si15 target to be 120 - 200 A, introducing nitrogen at 500 - 800 sccm, applying a substrate bias voltage of -40 to -100 V, controlling the rotation speed of the workpiece turntable in the furnace to be 2.0 - 5.0 rpm, and depositing the AlCrTiSiN high-entropy layer on the surface of the AlCrN / TiSiN nanomultilayers at 400 - 550 °C. The deposition time is 20 - 60 min.

6. The preparation method of the nano-multilayer gradient heterogeneous corrosion-resistant composite coating according to claim 1, characterized in that, Prepare the TiSiN top layer using an arc ion plating equipment. The specific parameters include: controlling the current of the Ti85Si15 target to be 120 - 200 A, introducing nitrogen at 500 - 800 sccm, applying a substrate bias voltage of -40 to -100 V, controlling the rotation speed of the workpiece turntable in the furnace to be 2.0 - 5.0 rpm, and depositing the TiSiN top layer on the surface of the AlCrTiSiN high-entropy layer at 400 - 550 °C. The deposition time is 10 - 30 min.

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