Sandwich structure diamond coating as well as preparation method and application thereof
The design of the sandwich structure diamond coating solves the problems of easy oxidation and poor bonding strength of the diamond coating at high temperatures, achieves high hardness and wear resistance, and is suitable for steel processing.
Patent Information
- Application Number
- CN202510992058.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-18
- Publication Date
- 2025-10-14
AI Technical Summary
Diamond coatings are prone to oxidation failure at high temperatures, and the coatings in traditional cemented carbide substrates have poor adhesion and wear resistance, making it difficult to process materials such as steel.
A sandwich structure diamond coating is used, including a ta-C base layer, a CVD diamond intermediate layer and a surface PVD nitride layer. By controlling the deposition sequence and process parameters, a high-bonding and oxidation-resistant coating is formed.
The coating has high hardness, excellent wear resistance and oxidation resistance, and the coated tool shows excellent cutting performance in steel processing, solving the problem of easy failure of the coating in the existing technology.
Smart Images
Figure CN120776240A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application belongs to the technical field of composite coating, and particularly relates to a sandwich structure diamond coating and a preparation method and application thereof. BACKGROUND
[0002] The diamond coating has high hardness, excellent wear resistance and heat conduction performance, and has been widely used for cutting of difficult-to-machine materials such as carbon fiber, graphite and glass. However, the diamond coating is difficult to withstand high temperature above 500 DEG C in the atmospheric environment, otherwise carbon is oxidized into carbon dioxide to cause failure. In addition, the traditional hard alloy contains Co, which causes graphitization of the diamond coating during deposition, thereby causing low diamond bond content, poor hardness and wear resistance of the coating. Therefore, the hard alloy needs to be chemically treated to remove Co in the industry, but the chemical Co removal process is difficult to accurately control, and the quality of the diamond coating is unstable, for example, insufficient Co removal, which causes easy graphitization of the diamond interface and low adhesion; excessive Co removal, which reduces the strength of the substrate and the adhesion and impact resistance of the coating. In addition, the diamond has high affinity with steel, is easy to adhere and induce tool collapse, and iron is a graphitization element, which accelerates the failure of the diamond tool. Therefore, the diamond coating is usually difficult to be used for machining steel products. The above problems greatly limit the industrial application of the diamond product. SUMMARY
[0003] To solve the above technical problems, the present application provides a sandwich structure diamond coating and a preparation method and application thereof. The sandwich structure diamond coating has high adhesion, excellent wear resistance and oxidation resistance, and the coating tool has more excellent cutting performance than the commercial diamond coating, ta-C coating (tetrahedral hydrogen-free amorphous carbon film coating) and nitride coating.
[0004] To achieve the above purpose, the present application provides the following technical solutions.
[0005] One of the technical solutions of the present application is as follows:
[0006] A sandwich structure diamond coating, comprising a ta-C bottom layer, a CVD diamond intermediate layer and a surface PVD nitride layer arranged in sequence from bottom to top, and the total thickness of the sandwich structure diamond coating is 6-18.5 microns.
[0007] Preferably, the thickness of the ta-C bottom layer is 0.1-0.5 microns.
[0008] Preferably, the thickness of the CVD diamond intermediate layer is 5-15 microns.
[0009] Preferably, the thickness of the surface PVD nitride layer is 1.0-3.0 microns.
[0010] The second technical scheme of the present application is as follows:
[0011] A preparation method of the sandwich structure diamond coating comprises the following steps: on the surface of a substrate, a ta-C undercoat layer is prepared by a physical vapor deposition method, a CVD diamond intermediate layer is prepared by a chemical vapor deposition method, and a surface PVD nitride layer is prepared by a PVD method (physical vapor deposition method).
[0012] Preferably, when the ta-C undercoat layer is prepared, the deposition process parameters of the physical vapor deposition method include: the substrate temperature is 450-550 DEG C, the nitrogen pressure is 0.5-3.0 Pa, the target current is 100-180 A, the substrate negative bias is -120 to -40 V, and the deposition time is 20-100 min.
[0013] More preferably, when the ta-C undercoat layer is prepared, the target material of the physical vapor deposition method is a graphite target material.
[0014] Preferably, when the CVD diamond intermediate layer is prepared, the deposition process parameters of the chemical vapor deposition method include: the substrate temperature is 900-1100 DEG C, the gas inlet is a hydrogen and methane mixed gas, the carbon source volume concentration is 1-5%, the deposition time is 5-15 h, the furnace gas pressure is 500-5000 Pa, the workpiece hot wire distance is 8-20 mm, and the hot wire power is 5-10 kW.
[0015] Preferably, when the surface PVD nitride layer is prepared, the deposition process parameters of the PVD method include: the substrate temperature is 420-550 DEG C, the nitrogen pressure is 1.0-5.0 Pa, the target current is 100-180 A, the substrate negative bias is -120 to -40 V, and the deposition time is 20-60 min.
[0016] More preferably, when the surface PVD nitride layer is prepared, the target material of the PVD method is a TiAl target material or an AlCr target material, and more specifically, the target material of the PVD method is Ti67Al33 or Al70Cr30.
[0017] Preferably, the substrate is a cemented carbide substrate, and more specifically, the substrate is a cemented carbide tool.
[0018] More preferably, before preparation, the substrate needs to be sandblasted and passivated, and then ultrasonically cleaned, and then argon ion etched.
[0019] The third technical scheme of the present application is as follows:
[0020] The sandwich structure diamond coating in the processing of steel parts.
[0021] Compared with the prior art, the present application has the following advantages and technical effects:
[0022] (1) The sandwich structure diamond coating of the present application comprises a ta-C undercoat layer, a CVD diamond intermediate layer and a surface PVD nitride layer arranged in turn from bottom to top, the ta-C undercoat layer is used as a Co barrier layer to inhibit the catalytic function of the substrate Co. Meanwhile, the diamond bonds in the ta-C undercoat layer can serve as nucleation sites for the subsequent preparation of the CVD diamond intermediate layer, thereby improving the nucleation rate and growth speed of the diamond coating and improving the interfacial bonding strength; and the deposition of the nitride coating on the surface of the CVD diamond intermediate layer isolates oxygen from the diamond coating, thereby exerting the high hardness and wear resistance of the diamond coating.
[0023] (2) The sandwich structure diamond coating of the present application has high hardness and bonding strength, excellent wear resistance and oxidation resistance, and the cutting tool prepared by the coating has excellent cutting performance, thereby solving the problem of tool failure in the prior art, and the coating of the present application can also be used in other cemented carbide substrates to improve the hardness and wear resistance of the substrate. BRIEF DESCRIPTION OF DRAWINGS
[0024] The accompanying drawings, which form a part of the present application, are used to provide further understanding of the present application, and the illustrative embodiments of the present application and their description serve the purpose of explaining the present application. The present application is not limited by the accompanying drawings.
[0025] Figure 1 The bonding strength test results of the coating of Example 1;
[0026] Figure 2 The bonding strength test results of the coating of Example 6;
[0027] Figure 3 The bonding strength test results of the coating of Comparative Example 2. DETAILED DESCRIPTION
[0028] The various illustrative embodiments of the present application will now be described in detail below, which should not be considered as limiting the present application, but should be understood as a more detailed description of certain aspects, features and embodiments of the present application.
[0029] It should be understood that the terms described in the present application are only used to describe the specific embodiments, and are not used to limit the present application. In addition, for the numerical range in the present application, it should be understood that each intermediate value between the upper limit and the lower limit of the range is also specifically disclosed. Each smaller range between any stated value or stated range and any other stated value or intermediate value within the stated range is also included in the present application. The upper limit and the lower limit of these smaller ranges can be independently included or excluded from the range.
[0030] Unless otherwise indicated, all technical and scientific terms have the same meaning as those one of ordinary skill in the art of the disclosure would understand. Although preferred methods and materials are described, any method and material similar or equivalent to those described herein can be used in the practice or testing of the present disclosure. All documents mentioned herein are incorporated by reference to disclose and describe in full the methods and / or materials useful in connection to the documents. In case of conflict between the content of the specification and that of any document incorporated herein by reference, the content of the specification prevails.
[0031] Many modifications and variations of the present disclosure described in the detailed description of the specification can be made without departing from the scope or spirit of the present disclosure, which will be apparent to those skilled in the art. Other implementations of the disclosure will be apparent to those skilled in the art from the specification. The specification and examples of the disclosure are merely illustrative.
[0032] As used herein, "comprise", "comprising", "have", "having", "include", "including", "contain", "containing", and the like, are open-ended terms that are intended to mean including, but not limited to.
[0033] The sandwich structure diamond coating according to the embodiment of the present disclosure comprises a ta-C undercoat layer, a CVD diamond intermediate layer and a surface PVD nitride layer arranged in order from bottom to top, and the total thickness of the sandwich structure diamond coating is 6-18.5 μm.
[0034] In the preferred embodiment of the present disclosure, the thickness of the ta-C undercoat layer is 0.1-0.5 μm.
[0035] In the preferred embodiment of the present disclosure, the thickness of the CVD diamond intermediate layer is 5-15 μm.
[0036] In the preferred embodiment of the present disclosure, the thickness of the surface PVD nitride layer is 1.0-3.0 μm.
[0037] The embodiment of the present disclosure also proposes a preparation method of the above sandwich structure diamond coating, comprising the following steps: on the surface of the substrate, a ta-C undercoat layer is prepared by physical vapor deposition, a CVD diamond intermediate layer is prepared by chemical vapor deposition (CVD method), and a surface PVD nitride layer is prepared by PVD (physical vapor deposition).
[0038] The performance of the sandwich structure coating depends on the synergistic effect of the functions of each layer, the "barrier-nucleation" of the ta-C undercoat layer, the "load-wear resistance" of the diamond intermediate layer, and the "protection-oxidation resistance" of the nitride surface layer form a progressive protection system. Changing the preparation order will destroy the functional matching between the layers, leading to uncontrolled diffusion of Co element, weakening of interface bonding, loss of high temperature stability, and ultimately overall deterioration of the performance of the coating. Specifically:
[0039] If the CVD diamond intermediate layer is prepared first, then the ta-C underlayer and the surface PVD nitride layer are prepared, the diamond layer is directly in contact with the cemented carbide substrate, the Co element in the substrate catalyzes the graphitization of diamond, which leads to the increase of diamond crystal defects, loose structure, and the decrease of hardness and wear resistance, the ta-C underlayer is not used as a nucleation medium, the nucleation rate of diamond on the substrate surface is insufficient, a weak interface is formed between the coating and the substrate, and peeling is prone to occur. Although there is a nitride layer on the surface, the diamond layer has been graphitized due to the Co catalysis, oxygen can still penetrate through the defects, the oxidation rate is accelerated at high temperature, the coating is prone to collapse or rapid wear due to insufficient hardness and poor adhesion during cutting, and the tool life is shortened.
[0040] Alternatively, the PVD nitride layer is deposited first, then the ta-C underlayer is deposited, and finally the CVD diamond intermediate layer is deposited, the PVD nitride layer has poor chemical compatibility with the cemented carbide substrate, there is a large stress at the interface, the ta-C underlayer cannot directly contact the substrate, the Co element diffuses to the diamond layer through the nitride layer, which leads to abnormal growth of diamond crystals, the hardness and wear resistance decrease, the nitride layer is buried in the underlayer, the surface diamond lacks protection, and the coating is prone to delamination due to interface stress concentration at high cutting temperature, and the cutting edge life is unstable.
[0041] Alternatively, the ta-C underlayer is deposited first, then the PVD nitride layer is deposited, and finally the CVD diamond intermediate layer is deposited, the PVD nitride layer (deposition temperature 450℃) decomposes during the CVD diamond deposition (950℃), the Al element diffuses to the ta-C layer to form a brittle phase, which leads to the decrease of diamond nucleation rate and uneven coating thickness, and the surface has no nitride protection at high temperature, the interface thermal stress between the nitride layer and the ta-C layer exceeds the bonding strength, and interlayer peeling is prone to occur during cutting.
[0042] In the preferred embodiment of the present application, when the ta-C underlayer is prepared, the deposition process parameters of the physical vapor deposition method include: the substrate temperature is 450-550℃, the nitrogen pressure is 0.5-3.0 Pa, the target current is 100-180 A, the substrate negative bias is -120 to -40 V, and the deposition time is 20-100 min.
[0043] In the preferred embodiment of the present application, when the ta-C underlayer is prepared, the target material of the physical vapor deposition method is a graphite target material.
[0044] In the preferred embodiment of the present application, the deposition process parameters of the chemical vapor deposition method include: the substrate temperature is 900-1100℃, the gas introduced is a mixture of hydrogen and methane, the carbon source volume concentration is 1-5%, the deposition time is 5-15 h, the gas pressure in the furnace is 500-5000 Pa, the distance between the workpiece and the hot wire is 8-20 mm, and the hot wire power is 5-10 kW.
[0045] In the preferred embodiment of the present application, when the surface PVD nitride layer is prepared, the deposition process parameters of the PVD method include: substrate temperature of 420-550℃; nitrogen pressure of 1.0-5.0Pa; target current of 100-180A; substrate negative bias of -120--40V; and deposition time of 20-60min.
[0046] In the preferred embodiment of the present application, when the surface PVD nitride layer is prepared, the target material of the PVD method is TiAl target material or AlCr target material, more specifically, the target material of the PVD method is Ti67Al33 or Al70Cr30.
[0047] In the preferred embodiment of the present application, the substrate is a cemented carbide substrate, more specifically, a cemented carbide tool.
[0048] In the preferred embodiment of the present application, before preparation, the substrate needs to be sandblasted and passivated, then ultrasonic cleaned, and then subjected to argon ion etching.
[0049] In the preferred embodiment of the present application, the equipment used in the physical vapor deposition method and the chemical vapor deposition method is the commonly used equipment in the field, for example, the physical vapor deposition is performed using an arc ion plating equipment.
[0050] The technical solutions of the present application are further described below through examples.
[0051] Example 1
[0052] A preparation method of a sandwich structure diamond coating, comprising the following steps:
[0053] (1) sandblasting and passivating a cemented carbide tool, then ultrasonic cleaning, and then argon ion etching;
[0054] (2) depositing a ta-C primer layer on the surface of the cemented carbide tool using a graphite target by a physical vapor deposition method, and the deposition process parameters are as follows: substrate temperature of 500℃, nitrogen pressure of 1.0Pa; target current of 160A; substrate negative bias of -60V; and deposition time of 60min, to obtain a ta-C primer layer with a thickness of 0.3μm;
[0055] (3) depositing a CVD diamond intermediate layer on the surface of the prepared ta-C primer layer using a CVD method, and the deposition process parameters are as follows: substrate temperature of 950℃, the gas introduced is a mixed gas of hydrogen and methane, wherein the carbon source concentration is 3%; deposition time of 12h; furnace gas pressure of 3000Pa; workpiece distance from hot wire of 12mm; and hot wire power of 8.5kW, to obtain a CVD diamond intermediate layer with a thickness of 12μm, and obtain a ta-C primer layer / CVD diamond intermediate layer composite layer;
[0056] (4) On the surface of the prepared CVD diamond interlayer, a surface PVD nitride layer (AlCrN coating) is deposited by PVD method using a metal target (Al70Cr30), and the deposition process parameters are as follows: substrate temperature is 450°C; nitrogen pressure is 3.0 Pa; target current is 160 A; substrate negative bias is -60 V; deposition time is 40 min, and a CVD diamond interlayer with a thickness of 2.0 μm is obtained. Thus, a ta-C underlayer / CVD diamond interlayer composite layer / surface PVD nitride layer, that is, a sandwich structure diamond coating, is obtained, and the total thickness is 14.3 μm.
[0057] Examples 2-6
[0058] (1) The same as Example 1;
[0059] (2) A ta-C underlayer is deposited on the surface of the cemented carbide tool by physical vapor deposition method using a graphite target, and the deposition process parameters are shown in Table 1;
[0060] Table 1 Related deposition process parameters for preparing ta-C underlayer in Examples 2-6
[0061]
[0062] (3) A CVD diamond interlayer is deposited on the surface of the prepared ta-C underlayer by CVD method, and the deposition process parameters are shown in Table 2, and the workpiece-hot filament distance is 12 mm;
[0063] Table 2 Related deposition process parameters for preparing CVD diamond interlayer in Examples 2-6
[0064]
[0065] (4) On the surface of the prepared CVD diamond interlayer, a surface PVD nitride layer (AlCrN coating) is deposited by PVD method using a metal target (Al70Cr30), and the deposition process parameters are shown in Table 3, and the parameters not specified are the same as those in Example 1.
[0066] Table 3 Related deposition process parameters for preparing surface PVD nitride layer in Examples 2-6
[0067]
[0068] Comparative Example 1
[0069] A commercially available AlCrN coated tool, and the thickness of the AlCrN coating is 2.8 μm.
[0070] Comparative Example 2
[0071] Commercially available diamond coated tool with diamond coating thickness of 12.6 μm.
[0072] Comparative Example 3
[0073] Commercially available ta-C coated tool with ta-C coating thickness of 2.4 μm.
[0074] Comparative Example 4
[0075] The same as Example 1 except that step (2) was omitted and other step parameters were kept the same.
[0076] Comparative Example 5
[0077] The same as Example 1 except that step (3) was omitted and other step parameters were kept the same.
[0078] Comparative Example 6
[0079] The same as Example 1 except that step (4) was omitted and other step parameters were kept the same.
[0080] Comparative Example 7
[0081] The same as Example 1 except that the preparation order of step (2) and step (3) was changed and other step parameters were kept the same.
[0082] Comparative Example 8
[0083] The same as Example 1 except that the preparation order of step (2) and step (4) was changed and other step parameters were kept the same.
[0084] Comparative Example 9
[0085] The same as Example 1 except that the preparation order of step (3) and step (4) was changed and other step parameters were kept the same.
[0086] Performance Test
[0087] The coating hardness and adhesion of Examples 1-6 and Comparative Examples 1-9 were tested by nanoindenter and Rockwell hardness tester; the oxidation resistance of the coating was tested by air oxidation test, the oxidation temperature was 800°C and the oxidation time was 2h; the wear resistance was tested by room temperature friction and wear tester, the counter ball was WC-6Co ball with a diameter of 6mm, the speed was 300r / min and the radius was 3mm; the cutting test was conducted, the machining parameters were 200m / min and a cutting depth of 2.5mm, the feed amount was 0.2mm / r, the machined material was 304 stainless steel, and the wear of the tool face of 0.3mm was the failure standard of the tool.
[0088] The adhesion test results of the coating of Example 1 and Example 6 are shown in Figure 1 , Figure 2The test results of the commercially available diamond coating of Comparative Example 2 are shown in Table 5. Figure 3 It can be seen that the ta-C undercoated CVD diamond coating of Example 6 has higher adhesion, and the adhesion reaches HF1 level (the highest adhesion level), which is higher than the commercially available HF3 level.
[0089] The test results of the properties of the coatings of Examples 1-6 are shown in Table 4, and the test results of the properties of the coatings of Example 1 and Comparative Examples 1-9 are shown in Table 5.
[0090] Table 4 Test results of the properties of the coatings of Examples 1-6
[0091]
[0092]
[0093] Table 5 Test results of the properties of the coatings of Example 1 and Comparative Examples 1-9
[0094] Sample Hardness / GPa Bonding force (N) Oxidation layer thickness / pm Wear rate Coated tool cutting life / m Example 1 90.4 HF1 0.12 3.6 7658.3 Comparative Example 1 29.6 HF1 0.13 4.5 3021.3 Comparative Example 2 96.8 HF2 Diamond layer powdered 2.1 1045.6 (tool collapse) Comparative Example 3 49.8 HF2 ta-C layer powdered 2.6 986.8 (tool collapse) Comparative Example 4 47.3 HF4 0.12 67.6 789.4 (coating flaking) Comparative Example 5 30.6 HF2 0.11 84.3 546.2 Comparative Example 6 91.3 HF1 Diamond layer powdered 2.1 948.6 (tool collapse) Comparative Example 7 40.6 HF4 0.13 78.5 656.3 (coating flaking) Comparative Example 8 89.6 HF2 ta-C and diamond layer powdered 456.3 1005.6 (tool collapse) Comparative Example 9 88.7 HF2 Diamond layer powdered 457.4 1128.3 (tool collapse)
[0095] As shown in Tables 4 and 5, the sandwich structure diamond coating of Examples 1-6 has high hardness, adhesion, wear resistance and high temperature oxidation resistance, and the coating cutter prepared by the present application can be used for machining steel products, and has excellent cutting performance when machining 304 stainless steel. In comparison, the commercially available diamond coating cannot be used for diamond machining. When the order of the bottom layer, the intermediate layer and the surface nitride layer is changed or a layer is missing, it is difficult to obtain a coating with high adhesion, high hardness, excellent wear resistance and high temperature oxidation resistance.
[0096] The above merely provides the preferred embodiments of the present application, but the protection scope of the present application is not limited thereto, and any changes or substitutions within the technical scope disclosed by the present application can be easily thought by those skilled in the art, which should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.
Claims
1. A sandwich structure diamond coating, characterized in that: The invention comprises a ta-C base layer, a CVD diamond middle layer and a surface PVD nitride layer which are sequentially arranged from bottom to top. The total thickness of the sandwich structure diamond coating is 6 to 18.5 μm.
2. The sandwich structure diamond coating according to claim 1, characterized in that: The thickness of the ta-C primer layer is 0.1 to 0.5 μm.
3. The sandwich structure diamond coating according to claim 1, characterized in that: The thickness of the CVD diamond intermediate layer is 5 to 15 μm.
4. The sandwich structure diamond coating according to claim 1, characterized in that: The thickness of the surface PVD nitride layer is 1.0 to 3.0 μm.
5. A method for preparing the sandwich structure diamond coating according to any one of claims 1 to 4, characterized in that: On the surface of the substrate, a ta-C base layer is prepared by physical vapor deposition, a CVD diamond intermediate layer is prepared by chemical vapor deposition, and a surface PVD nitride layer is prepared by physical vapor deposition.
6. The method for preparing a sandwich structure diamond coating according to claim 5, characterized in that: When preparing the ta-C base layer, the target material is a graphite target material, and the deposition process parameters of the physical vapor deposition method include: substrate temperature of 450-550°C, nitrogen pressure of 0.5-3.0 Pa; target current of 100-180A; substrate negative bias voltage of -120--40V; and deposition time of 20-100min.
7. The method for preparing a sandwich structure diamond coating according to claim 5, characterized in that: When preparing the CVD diamond intermediate layer, the deposition process parameters of the chemical vapor deposition method include: substrate temperature of 900-1100°C, the introduced gas is a mixture of hydrogen and methane, wherein the volume concentration of the carbon source is 1-5%; the deposition time is 5-15 hours; the gas pressure in the furnace is 500-5000 Pa; the distance between the workpiece and the hot wire is 8-20 mm; and the hot wire power is 5-10 kW.
8. The method for preparing a sandwich structure diamond coating according to claim 5, characterized in that: When preparing the surface PVD nitride layer, the target material is a TiAl target material or an AlCr target material, and the deposition process parameters of the physical vapor deposition method include: substrate temperature of 420-550°C; nitrogen pressure of 1.0-5.0 Pa; target current of 100-180 A; substrate negative bias voltage of -120--40 V; and deposition time of 20-60 min.
9. The method for preparing a sandwich structure diamond coating according to claim 5, characterized in that: The substrate is a cemented carbide substrate.
10. Use of the sandwich structure diamond coating according to any one of claims 1 to 4 in the processing of steel parts.