A multi-structure heterogeneous coating, its preparation method and application

Abstract

This invention discloses a multi-structured coating, its preparation method, and its application. The coating comprises a TiAlN substrate, an AlTiN gradient layer with increasing Al content, an AlTiN / TiSiN nanolayer, and a TiSiN nanocomposite layer, sequentially connected. The substrate is connected to the substrate. The AlTiN gradient layer with increasing Al content is immediately connected to the TiAlN substrate. The AlTiN / TiSiN nanolayer is a nano-multilayer structure composed of alternating AlTiN and TiSiN layers. The TiSiN layer is a nanocomposite structure composed of nanocrystalline embedded amorphous substrate. The total thickness of the coating is controlled between 1.0 and 6.0 μm. The multi-structured coating exhibits a bonding strength of 65–120 N with the substrate, a nanohardness of 32–35 GPa, and a fracture toughness of 5.9–10 MPa·m. 1 / 2 It has strong toughness and corrosion resistance, and high bonding strength. Its coated tools have a cutting life that is much longer than that of traditional AlTiN coated tools.

Description

Technical Field

[0001] This invention relates to the field of multi-structure coating technology, and more specifically, to a multi-structure coating consisting of a TiAlN substrate, an AlTiN gradient layer, an AlTiN / TiSiN nanolayer, and a TiSiN nanocomposite layer, as well as its preparation method and application. Background Technology

[0002] Cutting tools are known as the "teeth of industry" and are the foundation of high-end equipment manufacturing. Their performance directly determines the quality of products, production efficiency, and brand effect. One of the important factors affecting the performance of cutting tools and molds is the performance of their surface coating.

[0003] Mainstream single-structure coatings (TiN, AlTiN, TiSiN, AlTiN / TiSiN, etc.) used for cutting tools and molds on the market suffer from a contradiction between bonding strength and toughness. Furthermore, bonding strength is another key factor affecting the coating's durability. On the other hand, the cutting temperatures of difficult-to-machine materials such as high-strength steel and stainless steel can reach up to 1000℃, which conventional PVD coatings cannot withstand. For example, AlCrN series coatings undergo heterogeneous desolvation at high temperatures, forming hexagonal AlN structures, leading to a decrease in coating hardness and toughness; CrN decomposes at temperatures above 700℃, forming Cr and C. r2 The nitrogen phase reduces coating adhesion. Therefore, CrN or AlCrN series coatings are not suitable as underlayers to improve adhesion between the coating and the substrate. In contrast, TiAlN series coatings have higher thermal stability and can be selected as underlayers. Therefore, when designing the composition and structure of high-performance coatings, it is necessary to consider not only the structural influence but also the influence of the coating composition.

[0004] With development, multi-layered coating structures for cutting tools and molds have emerged, and research on nano-multilayer and gradient structure coatings is increasing. There is also a lot of research on the hardness, wear resistance and service life of coatings. Although the performance in some aspects has been greatly improved, there are still some defects. In particular, the consideration between toughness and bonding strength has not been effectively resolved. Summary of the Invention

[0005] Based on the needs and shortcomings of existing technologies, the primary objective of this invention is to overcome the defects in the performance of existing single-configuration and / or multi-layer structure coatings, and to provide a multi-structure coating that includes nanostructures, gradient structures, nano-multilayer structures, and nano-composite structures. The multi-structure coating of this invention has excellent properties such as good film-substrate bonding strength, coating hardness, and high toughness, and effectively balances the contradiction between coating bonding force and toughness, greatly improving the service life of cutting tools and molds.

[0006] To achieve the above objectives, one of the technical solutions adopted by the present invention is as follows:

[0007] A multi-structure coating comprises a TiAlN substrate, an AlTiN gradient layer with increasing Al content, an AlTiN / TiSiN nanolayer, and a TiSiN nanocomposite layer connected sequentially, wherein the substrate is connected to a substrate; the AlTiN gradient layer with increasing Al content is immediately connected to the TiAlN substrate; the AlTiN / TiSiN nanolayer is a nanolayer structure composed of alternating AlTiN and TiSiN layers, with at least 50 layers; the TiSiN nanocomposite layer is a nanocomposite structure composed of nanocrystalline embedded amorphous substrate. The total thickness of the multi-structure coating is controlled between 1.0 and 5.0 μm.

[0008] The technical approach of this invention is as follows: Gradient structures are used to adjust the interfacial stress distribution, significantly improving the adhesion between the coating and the substrate; nano-multilayer structures are used to improve the coating's hardness, strength, and fracture toughness; and nano-composite structures are used to improve the coating's wear resistance. In the composition design, a low-Al-content TiAlN layer is designed as the bottom layer of the coating. Simultaneously, Al solid solubility is used to regulate the coating's hardness; for example, the higher the Al content in the TiAlN or AlTiN layer, the more significant the solid solution strengthening effect and the higher the coating hardness. Finally, in the design of the multi-structure coating interface, the similarity or approximate thermophysical property matching of adjacent layers is used to improve the interlayer interfacial adhesion. Examples include: the TiAlN-AlTiN interface at the interface between the TiAlN bottom layer and the AlTiN gradient layer; the AlTiN-AlTiN interface at the interface between the AlTiN gradient layer and the AlTiN / TiSiN nano-multilayer layer; and the TiSiN-TiSiN interface at the interface between the AlTiN / TiSiN nano-multilayer layer and the TiSiN nanocomposite layer. Through the above-mentioned multi-structure configuration design and ingenious interlayer interface structure design, a coating with high adhesion and high toughness was finally prepared, which is conducive to expanding the application fields and industrial production scale of the coating.

[0009] Through numerous experiments during practical application, the inventors discovered that the adhesion, hardness, and fracture toughness of the coating significantly affect the cutting performance of the tool. Furthermore, they found that Al plays a solid solution strengthening role in the coating; the higher the Al content, the higher the coating hardness. Based on these findings, this invention employs a low-hardness TiAlN layer as the base layer and an AlTiN gradient layer with increasing hardness values, combined with a high-strength and tough AlTiN / TiSiN nanolayer and a wear-resistant TiSiN nanocomposite layer, to solve the problems of coating adhesion and toughness.

[0010] Specifically, by constructing a composite structure of TiAlN bottom layer and AlTiN gradient layer, the interfacial stress distribution is adjusted to improve the adhesion between the coating and the substrate; by using AlTiN / TiSiN nano-multilayer coating, the hardness and toughness of the coating are improved; and by using TiSiN, the hardness and wear resistance of the coating are improved.

[0011] Preferably, the substrate is a hard alloy or steel material.

[0012] Preferably, the thickness of the TiAlN substrate is 0.05–1.0 μm, and more preferably 0.2–0.8 μm.

[0013] Preferably, the thickness of the AlTiN gradient layer is 0.2–1.0 μm, and more preferably 0.5–1.0 μm.

[0014] Preferably, the thickness of the AlTiN / TiSiN nanolayer is 0.5–2.0 μm, more preferably 1.0–2.0 μm, wherein the thickness of the AlTiN layer is 2–10 nm and the thickness of the TiSiN layer is 2–10 nm.

[0015] Preferably, the thickness of the TiSiN nanocomposite layer is 0.2–2.0 μm, and more preferably 0.5–1.0 μm.

[0016] Preferably, the multi-structure coating has an adhesion strength of 65–120 N to the substrate, a nanohardness of 32–35 GPa, and a fracture toughness of 5.9–10 MPa·m. 1 / 2 .

[0017] In this application, the AlTiN / TiSiN nanomultilayer is a nanomultilayer structure composed of alternating AlTiN layers and TiSiN layers. Through multiple experiments, the inventors discovered that the alternating order of AlTiN layers and TiSiN layers in the AlTiN / TiSiN nanomultilayer, as well as the starting point of the AlTiN layer and the ending point of the TiSiN layer, are crucial. Otherwise, the interfacial bonding force between the multi-structure coating layers will be affected, ultimately impacting the coating's durability.

[0018] In this application, the total thickness of the multi-structured coating is controlled between 1.0 and 5.0 μm. Specifically, the inventors discovered through multiple experiments that if the thickness of the multi-structured heterogeneous coating is too large (greater than 5.0 μm), it will increase the brittleness of the multi-structured coating; while if the thickness is too small (less than 1.0 μm), the wear resistance of the multi-structured coating is insufficient, and the coating is easily worn.

[0019] To achieve the above objectives, the second technical solution adopted by the present invention is as follows:

[0020] A method for preparing a multi-structure coating includes the following steps:

[0021] Using an arc ion plating apparatus, a TiAlN underlayer is first deposited on the substrate surface using a TiAl target with low Al content. Then, an AlTiN gradient layer is deposited on the TiAlN underlayer using AlTi targets with varying Al contents. Following this, an AlTiN layer is deposited on the AlTiN gradient layer surface using an AlTi target, followed by a TiSiN layer, and so on, alternating between the two layers until a TiSiN layer is deposited. Finally, a TiSiN nanocomposite layer is deposited on the AlTiN / TiSiN nanomultilayer surface. Through this deposition process, a multi-structure heterogeneous coating consisting of a TiAlN underlayer, an AlTiN gradient layer, an AlTiN / TiSiN nanomultilayer, and a TiSiN nanocomposite layer is obtained.

[0022] Preferably, the substrate needs to be cleaned before use.

[0023] Preferably, the substrate is a hard alloy or steel material.

[0024] Preferably, the method for preparing the multi-structure coating includes the following specific steps:

[0025] S1: Ultrasonic degreasing, cleaning and drying of the substrate;

[0026] S2: Using an arc ion plating device, the current of the TiAl target (Al content less than 50 at.%) is controlled at 60-200A, nitrogen gas with a flow rate of 200-700 sccm is introduced, a substrate bias voltage of -40 to -150V is applied, and deposition is carried out on the substrate surface at 400-550℃ for 5-60 minutes to obtain the TiAlN underlayer;

[0027] S3: Control the TiAl target current to 60-200A, introduce nitrogen gas at a flow rate of 200-700sccm, apply a substrate bias voltage of -50--150V, and deposit an AlTiN gradient layer using TiAl targets with different Al contents at 400-550℃. The Al contents in the TiAl targets are 30 at.%, 50 at.%, 70 at.%, and 90 at.%, respectively. The TiAl target deposition sequence is 30 at.%, 50 at.%, 70 at.%, and 90 at.%, respectively. The target deposition time for each component is 5-10 min, and the total deposition time is 20-80 min, thereby preparing a TiAlN gradient layer with increasing Al content.

[0028] S4: Control the TiAl target current to 60-200A, introduce nitrogen gas at a flow rate of 200-700sccm, apply a substrate bias voltage of -50--150V, deposit an AlTiN layer using an AlTi target (Al content greater than 50 at.%) at 400-550℃, then deposit a TiSiN layer using a TiSi target, and repeat the cycle until TiSiN is deposited. The alternating deposition time is 0.5-2h, thereby preparing an AlTiN / TiSiN nanomultilayer.

[0029] S5: Control the TiSi target current to 60-200A, introduce nitrogen gas at a flow rate of 200-700sccm, apply a substrate bias voltage of -50 to -200V, and deposit on AlTiN / TiSiN nanolayers at 400-550℃ for 0.5-1h to prepare a TiSiN nanocomposite layer; thus, a multi-structure heterogeneous coating composed of TiAlN bottom layer - AlTiN gradient layer - AlTiN / TiSiN nanolayers - TiSiN nanocomposite layer is finally obtained.

[0030] Furthermore, the target deposition time for each component in step S3 is also called the single-target deposition time; a specific single-target deposition can be performed once or multiple times consecutively. For example, a TiAl target with an Al content of 30 at.% can be deposited once or multiple times; after the deposition is completed, TiAl targets with other Al contents can be deposited.

[0031] In step S2, the TiAlN bottom layer is deposited using a low-aluminum TiAl target with an Al content of less than 50 at.%; in step S3, the AlTiN deposition target is a TiAl target with an Al content of more than 50 at.%; in steps S3-S4, the TiSiN layer is obtained by depositing a TiSi target with a Si content of 10-25 at%. Furthermore, the low-aluminum TiAl target is a Ti70Al30 target, the TiAl target with an Al content of more than 50 at.% is an Al70Ti30 target, and the TiSi target is a Ti82Si18 target.

[0032] To achieve the above objectives, the third technical solution adopted by the present invention is as follows:

[0033] The above-mentioned multi-structure heterogeneous coatings are used in the preparation of cutting tools and molds.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] (1) By designing the coating composition and structure, a multi-structure coating with nanostructure, gradient structure, nano-multilayer structure and nano-composite structure was prepared. The multi-structure coating has an adhesion force of 65-120 N to the substrate, a nanohardness of 32-35 GPa, and a fracture toughness of 5.9-10 MPa·m. 1 / 2It effectively improves the film-substrate adhesion and coating toughness, and solves the contradiction between adhesion strength and toughness in the existing technology; in addition, the multi-structure coating also has good coating hardness.

[0036] (2) The multi-structure coating of the present invention can be applied to cutting tools and molds. The cutting length of the coated cutting tool is 1300-1700m, and it has excellent wear resistance and low interfacial stress, which can significantly improve the service life of cutting tools and molds. Attached Figure Description

[0037] Figure 1 The diagram shows the cross-sectional microstructure of the multi-structure coatings consisting of TiAlN bottom layer, AlTiN gradient layer, AlTiN / TiSiN nanolayer, and TiSiN nanocomposite layer in Examples 1-6. Detailed Implementation

[0038] The present invention is further illustrated below with reference to specific embodiments. These embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Experimental methods in the following embodiments that do not specify specific conditions are generally performed under conventional conditions in the art or as recommended by the manufacturer; the raw materials and reagents used, unless otherwise specified, are all commercially available from the conventional market. Any non-substantial changes and substitutions made by those skilled in the art based on the present invention are within the scope of protection claimed by the present invention.

[0039] Example 1

[0040] This embodiment provides a multi-structure heterogeneous coating, comprising: a cemented carbide substrate, a TiAlN underlayer, an AlTiN gradient layer with increasing Al content, an AlTiN / TiSiN nanolayer, and a TiSiN nanocomposite layer. The TiAlN underlayer is connected to the cemented carbide substrate.

[0041] The method for preparing the multi-structure heterogeneous coating includes the following specific steps:

[0042] S1: Ultrasonic degreasing, cleaning and drying of cemented carbide substrate;

[0043] S2: Using an arc ion plating apparatus, the current of the Ti70Al30 target (Al content of 30 at.%) was controlled at 160 A, nitrogen gas flow rate of 500 sccm was introduced, the rack speed was 4.5 rpm / min, a substrate bias voltage of -60 V was applied, and deposition was carried out on the substrate surface at 450 °C for 30 min to obtain a TiAlN underlayer; the thickness of the TiAlN underlayer was 0.5 μm.

[0044] S3: The TiAl target current is controlled at 160A, nitrogen gas is introduced at a flow rate of 600sccm, a substrate bias voltage of -80V is applied, the rack speed is 4.5rpm / min, and an AlTiN gradient layer is deposited on the TiAlN bottom layer surface in step S2 at 450℃ using TiAl targets with different Al contents. The Al contents in the TiAl targets are 30at.%, 50at.%, 70at.%, and 90at.%, respectively. The TiAl target deposition sequence is 30at.%, 50at.%, 70at.%, and 90at.%, respectively. The target deposition time for each composition is 15min, and the total deposition time is 60min. The thickness of the AlTiN gradient layer is 0.8μm, thereby preparing a TiAlN gradient layer with increasing Al content.

[0045] S4: The TiAl target current was controlled at 160A, nitrogen gas flow rate was 600sccm, a substrate bias voltage of -80V was applied, the rack speed was 4.5rpm / min, and an AlTiN layer was deposited using an Al70Ti30 target at 450℃. Then, a TiSiN layer was deposited using a Ti82Si18 target. The above deposition process was repeated until TiSiN was deposited. The deposition time was 1h, the modulation period was 10nm, and the thickness of the nanomultilayer was 1.0μm, thus preparing an AlTiN / TiSiN nanomultilayer.

[0046] S5: Control the TiSi target current to 160A, introduce nitrogen gas at a flow rate of 600sccm, apply a substrate bias voltage of -80V, and deposit on the AlTiN / TiSiN nanomultilayer surface at 450℃ for 1h to prepare a TiSiN nanocomposite layer with a thickness of approximately 1.0μm; finally, a multi-structure heterogeneous coating consisting of a TiAlN bottom layer, an AlTiN gradient layer, an AlTiN / TiSiN nanomultilayer, and a TiSiN nanocomposite layer is obtained, with a total thickness of 3.3μm.

[0047] Examples 2-6

[0048] Examples 2-6 provide multi-structure coatings composed of different TiAlN bottom layers, AlTiN gradient layers, AlTiN / TiSiN nanomultilayers, and TiSiN nanocomposite layers. Each of them includes a TiAlN bottom layer, an AlTiN gradient layer with increasing Al content, an AlTiN / TiSiN nanomultilayer, and a TiSiN nanocomposite layer connected in sequence, wherein the TiAlN bottom layer is connected to the cemented carbide substrate.

[0049] The preparation method of the multi-structure heterogeneous coatings described in Examples 2-6 includes the following specific steps:

[0050] S1: Same as in Example 1;

[0051] S2: TiAlN underlayers were prepared on a cemented carbide substrate using an arc ion plating apparatus. Specifically, the experimental parameters for Examples 2-6 are shown in the table below:

[0052] Table 1. Relevant experimental parameters for the preparation of TiAlN substrates in Examples 2-6

[0053]

[0054] S3: Controlling the TiAl target current to 60–200 A, introducing nitrogen gas at a flow rate of 200–700 sccm, applying a substrate bias voltage of -50–-150 V, and depositing AlTiN gradient layers using TiAl targets with different Al contents at 400–550 °C. The Al contents in the TiAl targets are 30 at.%, 50 at.%, 70 at.%, and 90 at.%, respectively. The TiAl target deposition sequence is 30 at.%, 50 at.%, 70 at.%, and 90 at.%, with each component requiring 5–20 min of target deposition and a total deposition time of 20–80 min, thus preparing a TiAlN gradient layer with increasing Al content. Specifically, the experimental parameters for Examples 2–6 are shown in the table below:

[0055] Table 2. Experimental parameters related to the preparation of gradient AlTiN layers in Examples 2-6.

[0056]

[0057]

[0058] Note: In Examples 3 and 4, TiAl targets with an Al content of 30 at.% were deposited twice, TiAl targets with an Al content of 50 at.% were deposited three times, TiAl targets with an Al content of 70 at.% were deposited three times, and TiAl targets with an Al content of 90 at.% were deposited twice; in Example 6, TiAl targets with an Al content of 30 at.% were deposited once, TiAl targets with an Al content of 50 at.% were deposited twice, TiAl targets with an Al content of 70 at.% were deposited twice, and TiAl targets with an Al content of 90 at.% were deposited once.

[0059] S4: Controlling the TiAl target current to 60–200 A, introducing nitrogen gas at a flow rate of 200–700 sccm, applying a substrate bias voltage of -50–-150 V, and depositing an AlTiN layer using an AlTi target (Al content greater than 50 at.%) at 400–550 °C, followed by depositing a TiSiN layer using a TiSi target, repeating this cycle until ending with TiSiN, with alternating deposition times of 0.5–2 h, thereby preparing an AlTiN / TiSiN nanolayer; specifically, the experimental parameters for Examples 2–6 are shown in the table below:

[0060] Table 3. Experimental parameters related to the preparation of AlTiN / TiSiN nanolayers in Examples 2-6.

[0061]

[0062]

[0063] S5: The TiSi target current was controlled at 60–200 A, nitrogen gas was introduced at a flow rate of 200–700 sccm, a substrate bias voltage of -50–-200 V was applied, and TiSiN / TiSiN nanocomposite layers were deposited on AlTiN / TiSiN nanolayers at 400–550 °C for 0.5–1 h to obtain the TiSiN nanocomposite layer; specifically, the experimental parameters of Examples 2–6 are shown in the table below:

[0064] Table 4. Relevant experimental parameters for the preparation of TiSiN layers in Examples 2-6.

[0065]

[0066] Comparative Example 1

[0067] This comparative example provides a mainstream TiAlN layer, the preparation method of which includes the following steps:

[0068] S1: Ultrasonic degreasing, cleaning, and drying of cemented carbide;

[0069] S2: Using an arc ion plating equipment, the target current of Ti67Al33 is controlled at 160A, nitrogen gas is introduced at a flow rate of 500sccm, a substrate bias voltage of -80V is applied, the workpiece rotation speed in the furnace is controlled at 4.5rpm, and a TiAlN layer with a thickness of 3.1μm is deposited on the surface of the cemented carbide substrate at 450℃ for 180min.

[0070] Comparative Example 2

[0071] This comparative example provides an AlTiN gradient layer, the preparation method of which includes the following steps:

[0072] S1: Ultrasonic degreasing, cleaning and drying of cemented carbide substrate;

[0073] S2: Using an arc ion plating apparatus, the AlTi target current is 160A, nitrogen gas flow rate is 500sccm, a substrate bias voltage of -80V is applied, the workpiece rotation speed in the furnace is controlled at 4.5rpm, and the deposition temperature is 450℃. An AlTiN gradient layer is deposited on the surface of cemented carbide using AlTi targets with different Al contents. The Al contents in the target materials are 30at.%, 50at.%, 70at.%, and 90at.%, respectively. The TiAl target deposition sequence is 30at.%, 50at.%, 70at.%, and 90at.%, respectively. The target deposition time for each composition is 45min, the total deposition time is 180min, and the total thickness of the gradient layer is approximately 3.0μm.

[0074] Comparative Example 3

[0075] This comparative example provides an AlTiN / TiSiN nanolayered coating, the preparation method of which includes the following steps:

[0076] S1: Ultrasonic degreasing, cleaning, and drying of cemented carbide;

[0077] S2: Using an arc ion plating apparatus, the current of both the Al37Ti33 target and the Ti82Si18 target is controlled at 160A, nitrogen gas with a flow rate of 500sccm is introduced, a substrate bias voltage of -80V is applied, and the workpiece rotation speed in the furnace is controlled at 4.5rpm. AlTi and TiSi targets are alternately deposited on the surface of cemented carbide at 450℃ for 3h to obtain AlTiN / TiSiN nanolayers with a thickness of 3.0μm.

[0078] Comparative Example 4

[0079] This comparative example provides a TiSiN layer, the preparation method of which includes the following steps:

[0080] S1: Ultrasonic degreasing, cleaning and drying of cemented carbide substrate;

[0081] S2: Using an arc ion plating equipment, the target current of Ti82Si18 is controlled at 160A, nitrogen gas with a flow rate of 500sccm is introduced, a substrate bias voltage of -80V is applied, the workpiece rotation speed in the furnace is controlled at 4.5rpm, and a TiSiN layer with a thickness of 2.9μm is deposited on the surface of cemented carbide at 450℃ for 3h.

[0082] Comparative Example 5

[0083] This comparative example provides a composite layer composed of a TiAlN layer and an AlTiN gradient layer, comprising a TiAlN layer and an AlTiN gradient layer connected in sequence, and its preparation method includes the following steps:

[0084] S1: Ultrasonic degreasing, cleaning, and drying of cemented carbide;

[0085] S2: Using an arc ion plating apparatus, a Ti67Al33 target current of 160A was used, nitrogen gas was introduced at a flow rate of 500 sccm, a substrate bias voltage of -80V was applied, and the deposition time was 60 min, resulting in a 1.0 μm TiAlN layer. Then, an AlTiN gradient layer was deposited using AlTi targets with different Al contents, with a deposition time of 30 min for each target, for a total deposition time of 120 min. Other deposition parameters were the same as the TiAlN underlayer, and the gradient layer thickness was approximately 2.0 μm. The final composite layer consisting of the TiAlN and AlTiN gradient layers had a thickness of approximately 3.0 μm.

[0086] Comparative Example 6

[0087] This comparative example provides a composite multilayer consisting of a TiAlN substrate, an AlTiN gradient layer, and an AlTiN / TiSiN nanolayer, the preparation method of which includes the following steps:

[0088] S1: Ultrasonic degreasing, cleaning, and drying of cemented carbide;

[0089] S2: Using an arc ion plating apparatus, the target current of Ti67Al33 was 160A, nitrogen gas flow rate was 500sccm, a substrate bias voltage of -80V was applied, and the deposition time was 30min to deposit a 0.5μm TiAlN underlayer. Then, an AlTiN gradient layer was deposited using AlTi targets with different Al contents, with a deposition time of 15min for each target, for a total deposition time of 60min. Other deposition parameters were the same as the TiAlN underlayer, and the thickness of the AlTiN gradient layer was approximately 1.0μm.

[0090] S3: The TiAl target current was controlled at 160A, nitrogen gas flow rate was 500 sccm, a substrate bias voltage of -80V was applied, the rack rotation speed was 4.5 rpm / min, and an AlTiN layer was deposited at 450℃ using an Al70Ti30 target. Then, a TiSiN layer was deposited using a Ti82Si18 target. This deposition process was repeated until a TiSiN layer was deposited. The deposition time was 1.5 h, resulting in an AlTiN / TiSiN nanomultilayer with a modulation period of 10 nm and a nanomultilayer thickness of 1.5 μm. The final composite multilayer consisting of a TiAlN bottom layer, an AlTiN gradient layer, and an AlTiN / TiSiN nanomultilayer has a thickness of approximately 3.0 μm.

[0091] Comparative Example 7

[0092] This comparative example provides a composite multilayer consisting of a TiAlN bottom layer, an AlTiN gradient layer, and a TiSiN nanocomposite layer. The preparation method includes the following steps:

[0093] S1: Ultrasonic degreasing, cleaning, and drying of cemented carbide;

[0094] S2: Using an arc ion plating apparatus, the target current of Ti67Al33 was 160A, nitrogen gas flow rate was 500sccm, a substrate bias voltage of -80V was applied, and the deposition time was 30min to deposit a 0.5μm TiAlN layer; then, an AlTiN gradient layer was deposited using AlTi targets with different Al contents, with a deposition time of 15min for each target, for a total deposition time of 60min. Other deposition parameters were the same as the TiAlN underlayer, and the gradient layer thickness was approximately 1.0μm.

[0095] S3: The TiSi target current was controlled at 160A, nitrogen gas was introduced at a flow rate of 500 sccm, a substrate bias voltage of -80V was applied, the rack rotation speed was 4.5 rpm / min, and a TiSiN layer was deposited using a Ti82Si18 target at 450℃ for 1.5 h. Thus, a composite multilayer consisting of a TiAlN substrate, an AlTiN gradient layer, and a TiSiN nanocomposite layer was obtained with a thickness of approximately 3.0 μm.

[0096] Comparative Example 8

[0097] This comparative example provides a multi-structure coating with a TiAlN base layer, an AlTiN gradient layer, a TiSiN / AlTiN nanolayer, and a TiSiN nanocomposite layer. The fabrication process parameters are the same as in Example 1, except for the deposition sequence of the nanolayer coating. In Example 1, the AlTiN gradient layer is connected to the TiSiN layer, ending with an AlTiN layer. This deposition sequence is exactly the opposite of that in Example 1.

[0098] Comparative Example 9

[0099] This comparative example provides a multi-structure coating with a TiAlN base layer, an AlTiN gradient layer, a TiSiN nanocomposite layer, and an AlTiN / TiSiN nanomultilayer. The preparation method is the same as that in Example 1, except that steps S3 and S4 in Example 1 are changed.

[0100] Comparative Example 10

[0101] This comparative example provides a multi-structure coating with a TiSiN / AlTiN nanolayer-AlTiN gradient layer-AlTiN bottom layer-TiSiN nanocomposite layer. The preparation method is the same as that in Example 1, except that steps S2 and S4 in Example 1 are changed.

[0102] Comparative Example 11

[0103] This comparative example provides a multi-structure coating with a TiAlN bottom layer, a TiSiN nanocomposite layer, an AlTiN / TiSiN nanomultilayer, and an AlTiN gradient layer. The preparation method is the same as that in Example 1, except that steps S3 and S5 in Example 1 are changed.

[0104] Performance testing:

[0105] The adhesion between the coatings and the substrate in Examples 1-6 and Comparative Examples 1-10 was tested using the scratch test method, and the fracture toughness of the coatings in Examples 1-6 and Comparative Examples 1-9 was tested using the indentation method. The cutting performance of the coated tools was verified by high-speed dry cutting of 316L stainless steel. The test results are as follows:

[0106] Table 5 Performance test results of multi-structure coatings in Examples 1-6

[0107]

[0108]

[0109] Table 6 Performance test results of the coatings in Example 1 and Comparative Examples 1-9

[0110]

[0111]

[0112] As shown in Tables 5 and 6, the coating-substrate bonding strength of Examples 1-6 of the present invention ranges from 69 to 118 N, the hardness ranges from 32.1 to 34.9 GPa, and the fracture toughness ranges from 5.9 to 9.1 MPa·m. 1 / 2 The cutting length of the coated tool ranges from 1304 to 1680 m, while the overall performance of the coatings and coated tools in Comparative Examples 1 to 11 is less than that in Example 1. This indicates that the present invention, through structural control and design, can improve the mechanical properties of TiAlN-gradient AlTiN-AlTiN / TiSiN-TiSiN multi-structure coatings and significantly improve the cutting life of the coated tools.

[0113] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A multi-structure heterogeneous coating comprising, sequentially connected, a TiAlN substrate, an AlTiN gradient layer with increasing Al content, an AlTiN / TiSiN nanolayer, and a TiSiN nanocomposite layer, wherein the substrate is connected to a substrate; the AlTiN gradient layer with increasing Al content is immediately connected to the TiAlN substrate; the AlTiN / TiSiN nanolayer is a nanolayer structure composed of alternating AlTiN and TiSiN layers, the nanolayer structure having at least 50 layers; the TiSiN nanocomposite layer is a nanocomposite structure composed of nanocrystalline embedded amorphous substrate; the total thickness of the multi-structure heterogeneous coating is controlled between 1.0 and 5.0 μm; The thickness of the TiAlN bottom layer is 0.05~1.0 μm; the thickness of the AlTiN gradient layer is 0.2~1.0 μm; the thickness of the AlTiN / TiSiN nanolayer is 0.5~2.0 μm; and the thickness of the TiSiN nanocomposite layer is 0.2~2.0 μm. The multi-structure heterogeneous coating exhibits a bonding strength of 65–120 N with the substrate, a nanohardness of 32–35 GPa, and a fracture toughness of 5.9–10 MPa·m. 1 / 2 ; The process includes the following steps: using an arc ion plating apparatus, firstly, a TiAlN underlayer is deposited on the substrate surface using a TiAl target with low Al content; then, an AlTiN gradient layer is deposited on the TiAlN underlayer surface using AlTi targets with different Al contents; subsequently, an AlTiN layer is deposited on the AlTiN gradient layer surface using an AlTi target, followed by a TiSiN layer, and so on, alternating between the two layers until a TiSiN layer is deposited; finally, a TiSiN nanocomposite layer is deposited on the AlTiN / TiSiN nanomultilayer surface; through the above deposition process, a multi-structure heterogeneous coating consisting of a TiAlN underlayer, an AlTiN gradient layer, an AlTiN / TiSiN nanomultilayer, and a TiSiN nanocomposite layer is obtained. The preparation method of the multi-structure heterogeneous coating includes the following specific steps: S1: Ultrasonic degreasing, cleaning and drying of the substrate; S2: Using an arc ion plating device, the TiAl target current is controlled at 60-200A, nitrogen gas with a flow rate of 200-700sccm is introduced, a substrate bias voltage of -40--150V is applied, and the substrate is deposited at 400-550℃ for 5-60min to obtain the TiAlN underlayer. S3: Control the TiAl target current to 60–200 A, introduce nitrogen gas at a flow rate of 200–700 sccm, apply a substrate bias voltage of -50–-150 V, and deposit an AlTiN gradient layer using TiAl targets with different Al contents at 400–550 °C. The Al contents in the TiAl targets are 30 at.%, 50 at.%, 70 at.%, and 90 at.%, respectively. The TiAl target deposition sequence is 30 at.%, 50 at.%, 70 at.%, and 90 at.%, with each component taking 5–10 min to deposit, and a total deposition time of 20–80 min, thereby preparing a TiAlN gradient layer with increasing Al content. S4: Control the TiAl target current to 60-200A, introduce nitrogen gas at a flow rate of 200-700sccm, apply a substrate bias voltage of -50--150V, deposit an AlTiN layer using an AlTi target at 400-550℃, then deposit a TiSiN layer using a TiSi target, repeat the cycle, and finally finish with TiSiN, with alternating deposition times of 0.5-2h, thereby preparing an AlTiN / TiSiN nanomultilayer. S5: Control the TiSi target current to 60-200A, introduce nitrogen gas at a flow rate of 200-700sccm, apply a substrate bias voltage of -50 to -200V, and deposit on AlTiN / TiSiN nanolayers at 400-550℃ for 0.5-1h to prepare a TiSiN nanocomposite layer; thus, a multi-structure heterogeneous coating composed of TiAlN bottom layer - AlTiN gradient layer - AlTiN / TiSiN nanolayers - TiSiN nanocomposite layer is finally obtained.

2. The multi-structure heterogeneous coating according to claim 1, characterized in that, The thickness of the TiAlN bottom layer is 0.2–0.8 μm; the thickness of the AlTiN gradient layer is 0.5–1.0 μm; the thickness of the AlTiN / TiSiN nanolayer is 1.0–2.0 μm; and the thickness of the TiSiN nanocomposite layer is 0.5–1.0 μm.

3. The multi-structure heterogeneous coating according to claim 1 or 2, characterized in that, The AlTiN / TiSiN nanomultilayer has an AlTiN layer thickness of 2~10 nm and a TiSiN layer thickness of 2~10 nm.

4. The multi-structure heterogeneous coating according to claim 1, characterized in that, The substrate is either a cemented carbide or a steel material.

5. The multi-structure heterogeneous coating according to claim 1, characterized in that, In step S2, the TiAlN bottom layer is deposited using a low-aluminum TiAl target with an Al content of less than 50 at.%; in step S4, the AlTiN layer is deposited using a TiAl target with an Al content of more than 50 at.%; in steps S4-S5, the TiSiN layer is obtained by depositing a TiSi target with a Si content of 10-25 at.

6. The application of the multi-structure heterogeneous coating as described in any one of claims 1 to 5 in cutting tools and mold products.

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