Cr-doped ti al si n multilayer coating and method for producing the same

Abstract

The present application relates to a kind of Cr-doped TiAlSiN multilayer coating and its preparation method, the multilayer coating includes the TiN layer (2) of substrate (1) surface, TiAlN layer (3), TiAlSiN layer (4) and TiAlSiCrN layer (5), the total thickness of the multilayer coating is 2.7~3.2 μm;The method specifically is: using physical vapor deposition in substrate (1) surface layered deposition TiN layer (2), TiAlN layer (3), TiAlSiN layer (4) and TiAlSiCrN layer (5);The preparation process parameters include: nitrogen gas volume flow is 160~200sccm, vacuum degree is 2.0~4.2Pa, temperature is 400~500 ℃, etching bias is -800~-700V, deposition bias is -120~-80V.Compared with prior art, the present application improves coating oxidation resistance, prolongs service life.

Description

Technical Field

[0001] This invention belongs to the field of physical vapor deposition coating technology, and relates to a Cr-doped TiAlSiN multilayer coating and its preparation method. Background Technology

[0002] TiAlSiN coatings prepared using physical vapor deposition (PVD) are widely used in the cutting tool industry due to their high hardness and wear resistance. However, the coatings have poor oxidation resistance, which prevents the tool life from meeting the ideal requirements in industry.

[0003] Patent CN104862652A discloses a method for preparing a TiAlSiN superhard gradient coating, including a step of sandblasting and cleaning the workpiece surface, and a step of depositing the TiAlSiN superhard gradient coating on the workpiece using a cathodic ion plating process. The method comprises six stages: the first stage prepares a Ti base coating; the second stage prepares a TiN gradient coating; the third stage prepares a TiAl gradient coating; the fourth stage prepares a TiAlN gradient coating; the fifth stage prepares a SiN gradient coating; the sixth stage prepares a TiSiN gradient coating; and finally, the coating surface is polished. However, the coating in this patent has weak oxidation resistance. During high-speed dry cutting, due to the excessively high temperature, the oxidation resistance of the coating is crucial, therefore this coating cannot meet the requirements of industrial processing.

[0004] Patent CN113493896A discloses a physical vapor deposition (PVD) metal-ceramic composite self-lubricating medium coating and its preparation method. The coating includes a Ti layer, a TiN layer, a TiCN layer, and a TiCN / aC layer sequentially deposited on a substrate by PVD. However, the coatings in this patent have a large difference in the coefficient of thermal expansion between them, resulting in high residual stress, weak adhesion, and a tendency to peel off and fail. Summary of the Invention

[0005] The purpose of this invention is to overcome at least one defect of the prior art by providing a Cr-doped TiAlSiN multilayer coating and its preparation method. This invention has high bonding strength, stronger oxidation resistance than TiAlSiN coatings, a simple preparation process, and improved coating service life.

[0006] The objective of this invention can be achieved through the following technical solutions:

[0007] One of the technical solutions of the present invention is to provide a Cr-doped TiAlSiN multilayer coating, the multilayer coating comprising a TiN layer, a TiAlN layer, a TiAlSiN layer and a TiAlSiCrN layer on the surface of a substrate, wherein the total thickness of the multilayer coating is 2.7 to 3.2 μm.

[0008] In recent years, doping TiAlSiN coatings with Cr has become a research focus because Cr-doped coatings exhibit strong oxidation resistance. Therefore, obtaining high-performance TiAlSiCrN coatings has become a key breakthrough technology. The multilayer coating structure is TiN / TiAlN / TiAlSiN / TiAlSiCrN. Since the coefficient of thermal expansion of TiN coatings differs significantly from that of TiAlSiCrN coatings, the aforementioned coating structure reduces the difference in the coefficient of thermal expansion between adjacent coatings, thereby reducing residual stress and internal stress within the coating, resulting in better fatigue wear resistance.

[0009] Furthermore, the thickness of the TiN layer is 0.2–0.3 μm.

[0010] Furthermore, the thickness of the TiAlN layer is 1.5–1.7 μm.

[0011] The internal stress of the TiAlSiCrN layer is greater than that of the TiAlN layer. The thicker the TiAlSiCrN layer, the more prone the coating is to peeling and failure during use. Therefore, a thicker TiAlN layer was designed as an intermediate layer to improve the load-bearing capacity of the film and reduce the internal stress of the coating.

[0012] Furthermore, the thickness of the TiAlSiN layer is 0.8–0.9 μm.

[0013] Furthermore, the thickness of the TiAlSiCrN layer is 0.2–0.3 μm.

[0014] The reason for the relatively thin TiAlSiCrN layer is as follows:

[0015] (1) If the layer is too thick, the stress will rise sharply, resulting in a low bonding strength of the final deposited coating.

[0016] (2) The thickening of this layer will cause the internal defects to increase sharply, thereby accelerating the migration of the metal ions of the bottom layer to the outside at high temperature, forming loose oxides on the surface, which will eventually lead to a decrease in the oxidation resistance of the coating.

[0017] One of the technical solutions of the present invention is to provide a method for preparing a Cr-doped TiAlSiN multilayer coating, the method specifically comprising: depositing a TiN layer, a TiAlN layer, a TiAlSiN layer and a TiAlSiCrN layer in layers on the substrate surface by physical vapor deposition;

[0018] The preparation process parameters include: nitrogen volume flow rate of 160-200 sccm, vacuum degree of 2.0-4.2 Pa, temperature of 400-500℃, etching bias of -800--700V, deposition bias of -120--80V, and target materials of AlTi, TiSi, Ti and Cr respectively.

[0019] Furthermore, the TiN layer preparation process parameters include: Ti target current of 180-200A and deposition time of 25-30min.

[0020] Furthermore, the process parameters for preparing the TiAlN layer include: Ti target current of 180–200 A, AlTi target current of 160–180 A, and deposition time of 85–90 min.

[0021] Furthermore, the process parameters for preparing the TiAlSiN layer include: TiSi target current of 160–180 A, AlTi target current of 120–180 A, and deposition time of 45–50 min.

[0022] Furthermore, the process parameters for preparing the TiAlSiCrN layer include: TiSi target current of 160–180 A, AlTi target current of 120–180 A, Cr target current of 120–180 A, and deposition time of 25–30 min.

[0023] Since this coating is primarily used in high-speed dry cutting applications, the temperature of the coated tools often reaches 1000℃ or even higher during use. The oxides formed by this coating above 800℃ are mostly (Al,Cr)₂O₃, which exhibits stronger oxidation resistance than Al₂O₃, TiO₂, and Cr₂O₃, significantly enhancing the coating's oxidation resistance.

[0024] Compared with the prior art, the present invention has the following advantages:

[0025] (1) The present invention uses four layers of coatings to make the preparation process simple, the thickness design reasonable, the coating thermal expansion coefficient low, the coating internal stress low, and the coating bonding strength greatly improved.

[0026] (2) The TiAlSiCrN layer of the present invention is thinner than other base layers, and the coating is more likely to form a dense oxide on the surface during the oxidation process, which makes the coating more resistant to oxidation and improves the service life of the coating. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the structure of the Cr-doped TiAlSiN multilayer coating in an embodiment of the present invention;

[0028] Figure 2This is a comparison diagram of the oxidation depth of the coating samples in the embodiments and comparative examples of the present invention.

[0029] Explanation of markings in the diagram:

[0030] 1—Matrix, 2—TiN layer, 3—TiAlN layer, 4—TiAlSiN layer, 5—TiAlSiCrN layer. Detailed Implementation

[0031] The present invention will now be described in detail with reference to specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0032] Unless otherwise specified, the equipment used in the following embodiments is conventional equipment in the art; unless otherwise specified, the reagents used are commercially available products or prepared by conventional methods in the art. In the following embodiments, unless otherwise described in detail, conventional experimental methods in the art can be used.

[0033] Example:

[0034] A Cr-doped TiAlSiN multilayer coating, such as Figure 1 As shown, the process involves sequentially depositing a TiN layer 2, a TiAlN layer 3, a TiAlSiN layer 4, and a TiAlSiCrN layer 5 on the surface of a substrate 1 using physical vapor deposition (PVD). The thickness of the TiN layer 2 is 0.2–0.3 μm, the thickness of the TiAlN layer 3 is 1.5–1.7 μm, the thickness of the TiAlSiN layer 4 is 0.8–0.9 μm, and the thickness of the TiAlSiCrN layer 5 is 0.2–0.3 μm.

[0035] A method for preparing a Cr-doped TiAlSiN multilayer coating, the specific steps of which are as follows:

[0036] (1) The substrate 1 is made of 304 stainless steel with dimensions of 25×25×4mm. The acetone solution is a solution with a concentration of 80% prepared by 4L of acetone and 1L of distilled water. The substrate 1 is placed in the acetone solution for ultrasonic cleaning for 15min, then cleaned by immersion in 95% ethanol, and then dried with a hair dryer.

[0037] (2) Introduce argon gas at 200 sccm. Clean the Ti, AlTi, TiSi and Cr targets in sequence against the baffle for 8 minutes under a current of 120A. The etching bias voltage is -750V to remove impurities from the surface of the target material.

[0038] (3) Preparation of TiN layer 2: Nitrogen gas at 180 sccm was introduced, the vacuum degree was 3.0 Pa, the temperature was 450℃, the deposition bias voltage was -100V, the Ti target current was 190A, and the deposition time was 25 min, and a 0.2 μm TiN coating 2 was obtained on the substrate 1.

[0039] (4) Preparation of TiAlN layer 3: Nitrogen gas at 180 sccm was introduced, the vacuum degree was 3.0 Pa, the temperature was 450℃, the deposition bias voltage was -100V, the Ti target current was 190A, the AlTi target current was 170A, and the deposition time was 85min. A 1.5μm TiAlN coating 3 was obtained on TiN layer 2.

[0040] (5) Preparation of TiAlSiN layer 4: Nitrogen gas at 180 sccm was introduced, the vacuum degree was 3.0 Pa, the temperature was 450℃, the deposition bias voltage was -100V, the TiSi target current was 170A, the AlTi target current was 150A, and the deposition time was 45min. A 0.8μm TiAlSiN coating 4 was obtained on TiAlN layer 3.

[0041] (6) Preparation of TiAlSiCrN layer 5: Nitrogen gas at 180 sccm was introduced, the vacuum degree was 3.0 Pa, the temperature was 450℃, the deposition bias voltage was -100V, the TiSi target current was 170A, the AlTi target current was 150A, the Cr target current was 150A, and the deposition time was 30 min. A 0.3 μm TiAlSiCrN coating 5 was obtained on TiAlSiN layer 4.

[0042] Comparative example:

[0043] A TiAlSiN multilayer coating is prepared using a method that is basically the same as in Example 1, except that a TiAlSiCrN layer 5 is not deposited.

[0044] An oxidation experiment on a coated sample, the specific steps of which are as follows:

[0045] The examples and comparative examples were placed in the same high-temperature oxidation furnace. The temperature was first raised from room temperature to 400°C over a period of 62.5 minutes at a rate of approximately 6°C / min, and held for 10 minutes. Then, the temperature was raised to 800°C over a period of 80 minutes at a rate of 5°C / min. Finally, the temperature was raised from 800°C to 1000°C over a period of 40 minutes at a rate of 5°C / min. After holding at 1000°C for 2 hours, the furnace was cooled down over a period of 195 minutes at a rate of approximately 5°C / min. Once the temperature had dropped to room temperature, the oxidation depth of the two coating samples was compared.

[0046] like Figure 2As shown, in an environment of 1000℃, the comparative example was completely oxidized, with an oxidation depth of 2.5μm, and the oxidized portion accounted for 100% of the total coating thickness. In contrast, the oxidation depth of the example was only 2.0μm, and the oxidized portion accounted for 70% of the total coating thickness, a 30% reduction in the oxidation depth percentage compared to the comparative example. This demonstrates that the TiAlSiCrN coated sample exhibits better oxidation resistance.

[0047] A scratch test on a coated sample, the specific steps of which are as follows:

[0048] Scratch tests were conducted on both the example and the comparative examples. The scratch test parameters were as follows: load increase rate 60 N / min, scratch speed 2 mm / min, and load increased from 5 N to 125 N. The critical loads (LC) of the two coatings were finally obtained, as shown in Table 1.

[0049] Table 1 Comparison of critical loads of coatings in the examples and comparative examples.

[0050] sample Comparative Example Example LC / N 48 60

[0051] The scratch test showed that the bonding strength of the coating in the example was 60 N, while the bonding strength of the coating in the comparative example was 48 N. This indicates that the bonding strength of the TiAlSiCrN coating was significantly improved.

[0052] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A Cr-doped TiAlSiN multilayer coating, characterized in that, The multilayer coating comprises a TiN layer (2), a TiAlN layer (3), a TiAlSiN layer (4) and a TiAlSiCrN layer (5) on the surface of a substrate (1), the total thickness of the multilayer coating is 2.7-3.2 μm, and the multilayer coating is used in the field of high-speed dry cutting; The thickness of the TiN layer (2) is 0.2-0.3 μm; The thickness of the TiAlN layer (3) is 1.5-1.7 μm; The thickness of the TiAlSiN layer (4) is 0.8-0.9 μm; The thickness of the TiAlSiCrN layer (5) is 0.2-0.3 μm; The preparation process parameters of the TiN layer (2) include that the Ti target current is 180-200 A, and the deposition time is 25-30 min; The preparation process parameters of the TiAlN layer (3) include that the Ti target current is 180-200 A, the AlTi target current is 160-180 A, and the deposition time is 85-90 min; The preparation process parameters of the TiAlSiN layer (4) include that the TiSi target current is 160-180 A, the AlTi target current is 120-180 A, and the deposition time is 45-50 min; The preparation process parameters of the TiAlSiCrN layer (5) include that the TiSi target current is 160-180 A, the AlTi target current is 120-180 A, the Cr target current is 120-180 A, and the deposition time is 25-30 min.

2. A method of producing a Cr-doped TiAlSiN multilayer coating as claimed in claim 1, characterized in that The method specifically comprises: layer-by-layer deposition of a TiN layer (2), a TiAlN layer (3), a TiAlSiN layer (4) and a TiAlSiCrN layer (5) on the surface of a substrate (1) by physical vapor deposition; The preparation process parameters include that the nitrogen gas volume flow rate is 160-200 sccm, the vacuum degree is 2.0-4.2 Pa, the temperature is 400-500 ℃, the etching bias voltage is -800--700 V, the deposition bias voltage is -120--80 V, and the target materials are an AlTi target, a TiSi target, a Ti target and a Cr target.

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