Crn / craln / tialn nanolayer and method for manufacturing the same

Abstract

The present application relates to a kind of CrN / CrAlN / TiAlN nano multilayer and its preparation method, the nano multilayer includes sequentially deposited on the substrate surface CrN primer layer and the CrN / CrAlN / TiAlN composite multilayer with periodic modulation structure, one cycle of the CrN / CrAlN / TiAlN composite multilayer includes the CrN layer of innermost layer, the CrAlN layer of transition layer and the TiAlN layer of outermost layer, the total thickness of nano multilayer when the CrN / CrAlN / TiAlN composite multilayer adopts one cycle is 269-315nm, the number of cycles of the CrN / CrAlN / TiAlN composite multilayer is 1-600.Compared with prior art, the present application improves coating hardness, high temperature resistance and oxidation resistance, so that the service life of coating is greatly enhanced.

Description

Technical Field

[0001] This invention belongs to the field of physical vapor deposition coating surface modification technology, and relates to a CrN / CrAlN / TiAlN nanolayer and its preparation method. Background Technology

[0002] As an important surface modification technology, coating protection technology has been applied in an increasingly wide range of applications and has also developed rapidly. In particular, surface engineering technology based on magnetron sputtering technology has also been developed vigorously. Its development and application have played a very important role in improving the cutting performance of cutting tools and thus promoting the progress of cutting technology.

[0003] Coated cutting tools combine the advantages of high wear resistance and low friction coefficient of coatings with the high toughness and high strength of base materials, significantly improving the mechanical properties of cutting tools. However, their oxidation resistance cannot meet the needs of modern high-speed dry cutting technology, and they are prone to peeling and protective failure due to high temperatures during use. Therefore, the development and expansion of new coatings are of great significance.

[0004] Patent CN108531874A discloses a method for preparing a CrAlN / TiAlN nano-multilayer hard coating, using Ti as the transition layer sputtering target and CrAl alloy and TiAl alloy targets as multilayer film sputtering targets. However, the coating of this patent has poor oxidation resistance. During high-speed dry cutting, due to the excessively high temperature, the coating's oxidation resistance is required to be high. When a certain temperature is reached, TiO2 rapidly deposits in defects and cracks in the coating, and the continuous growth of Ti oxides leads to crack propagation and even peeling. Oxygen rapidly enters the interior of the coating, reducing its oxidation resistance. Therefore, this patent coating cannot meet the requirements of industrial processing.

[0005] Patent CN112941463A discloses a nano-multilayer oxynitride corrosion-resistant protective coating for titanium alloy surfaces, its preparation method, and its application. The protective coating comprises, from bottom to top, a substrate, a Cr underlayer, a CrN transition layer, and a CrON / TiON nano-multilayer; the CrON / TiON nano-multilayer is formed by alternating deposition of CrON and TiON layers. Although this patented coating uses alternating deposition of CrON and TiON layers to enhance its corrosion resistance, it exhibits high brittleness and is easily subjected to impact and stress, leading to cracks or spalling. Oxygen then rapidly penetrates the coating, reducing its oxidation resistance. Therefore, this patented coating still has shortcomings. Summary of the Invention

[0006] The purpose of this invention is to overcome at least one defect of the prior art and provide a CrN / CrAlN / TiAlN nanolayer and its preparation method. This invention improves the coating hardness, high temperature resistance and oxidation resistance, and greatly enhances the service life of the coating.

[0007] The objective of this invention can be achieved through the following technical solutions:

[0008] One of the technical solutions of the present invention is to provide a CrN / CrAlN / TiAlN nanomultilayer, which includes a CrN underlayer and a CrN / CrAlN / TiAlN composite multilayer with a periodic modulation structure sequentially deposited on the surface of a substrate. One cycle of the CrN / CrAlN / TiAlN composite multilayer includes an innermost CrN layer, a transition CrAlN layer and an outermost TiAlN layer. When the CrN / CrAlN / TiAlN composite multilayer uses one cycle, the total thickness of the nanomultilayer is 269-315 nm, and the number of cycles of the CrN / CrAlN / TiAlN composite multilayer is 1-600.

[0009] Furthermore, the thickness of the CrN substrate is 260–300 nm, and the total thickness of one cycle of the CrN / CrAlN / TiAlN composite multilayer is 9–15 nm.

[0010] Furthermore, the thickness of the CrN layer is 3–5 nm, the thickness of the CrAlN layer is 4–6 nm, and the thickness of the TiAlN layer is 2–4 nm.

[0011] One of the technical solutions of this invention is to provide a method for preparing CrN / CrAlN / TiAlN nanolayers. This method uses magnetron sputtering with a Cr target, a CrAl alloy target, and a TiAl alloy target as sputtering targets to prepare CrN / CrAlN / TiAlN nanolayers on a substrate surface, comprising the following steps:

[0012] S1. Matrix pretreatment: Clean the matrix;

[0013] S2. Target cleaning: Inert gas is introduced to clean Cr targets, CrAl targets and TiAl targets, removing impurities from the target surface;

[0014] S3. Substrate treatment: Inert gas is introduced, and the substrate is etched using a Cr target;

[0015] S4, CrN underlayer preparation: Reactive gas is introduced, and Cr target is used for deposition to obtain CrN underlayer;

[0016] S5, CrN layer preparation: The reaction gas is introduced and a Cr target is used for deposition to obtain a CrN layer;

[0017] S6, Preparation of CrAlN layer: The reaction gas is introduced and CrAl target is used for deposition to obtain CrAlN layer;

[0018] S7. Preparation of TiAlN layer: The reaction gas is introduced and deposited using a TiAl target to obtain a TiAlN layer.

[0019] As a preferred technical solution, the method for cleaning the substrate in step S1 includes the following steps:

[0020] The substrate is ultrasonically cleaned in the first cleaning solution, then immersed in the second cleaning solution, and finally dried.

[0021] As a preferred technical solution, the first cleaning solution includes acetone with a concentration of 70-90%, and the ultrasonic cleaning frequency is 20-40kHz, with a time of 10-20min.

[0022] The second cleaning solution includes ethanol with a concentration of 90-99%, and the soaking and cleaning time is 5-10 minutes.

[0023] Furthermore, the flow rate of the inert gas in step S2 is 150–210 sccm;

[0024] The current for cleaning Cr, CrAl, and TiAl targets was 100–130 A, and the time was 10–15 min.

[0025] As a preferred technical solution, the inert gas in step S2 is argon.

[0026] Furthermore, in step S3, the flow rate of the inert gas is 150–210 sccm, the vacuum degree is 3.0–5.2 Pa, and the temperature is 350–450 °C.

[0027] The etching bias voltage is -850 to -750V, the Cr target power is 100 to 120W, and the etching time is 10 to 15 minutes.

[0028] As a preferred technical solution, the inert gas in step S3 is argon.

[0029] Furthermore, in step S4, the reaction gas is nitrogen, with a flow rate of 160–200 sccm, a vacuum degree of 3.0–5.2 Pa, and a temperature of 350–450 °C;

[0030] The deposition bias voltage was -115 to -75V, the Cr target power was 260 to 320W, and the deposition time was 26 to 30 minutes.

[0031] Furthermore, in step S5, the reaction gas is nitrogen, with a flow rate of 160–200 sccm, a vacuum degree of 3.0–5.2 Pa, and a temperature of 350–450 °C;

[0032] The deposition bias voltage was -115 to -75 V, the Cr target power was 100 to 160 W, the Cr atomic percentage content was 99.80 to 99.99%, and the deposition time was 1.5 to 2.5 min.

[0033] Furthermore, in step S6, the reaction gas is nitrogen, with a flow rate of 160–200 sccm, a vacuum degree of 3.0–5.2 Pa, and a temperature of 350–450 °C;

[0034] The deposition bias voltage was -115 to -75 V, the CrAl target power was 100 to 160 W, the Cr atomic percentage content was 28 to 32%, the Al atomic percentage content was 68 to 72%, and the deposition time was 2 to 3 min.

[0035] Furthermore, in step S7, the reaction gas is nitrogen, with a flow rate of 160–200 sccm, a vacuum degree of 3.0–5.2 Pa, and a temperature of 350–450 °C;

[0036] The deposition bias voltage was -115 to -75 V, the TiAl target power was 100 to 160 W, the Ti atomic percentage content was 32 to 34%, the Al atomic percentage content was 66 to 68%, and the deposition time was 1 to 2 min.

[0037] In recent years, coating development has gradually shifted from binary nitride coatings to multi-component nitride coatings, progressively improving the high-temperature oxidation resistance and other mechanical properties of the substrate material. The composite multilayer structure is CrN / CrAlN / TiAlN. The addition of Cr in the CrN underlayer promotes the formation of a dense oxide layer on the surface, thereby improving the coating's oxidation resistance. Furthermore, the coating's oxidation resistance increases with increasing Cr content.

[0038] Since this invention is mostly used in high-speed dry cutting, the temperature of the coated tool often reaches above 1000℃ during use. The oxide generated by this invention at temperatures above 750-850℃ is mostly (Al,Cr)2O3, which has stronger oxidation resistance than Al2O3, TiO2 and Cr2O3, and greatly improves the oxidation resistance of the coating.

[0039] Compared with the prior art, the present invention has the following beneficial effects:

[0040] (1) The present invention performs etching treatment on the substrate, and then deposits a CrN base layer and a CrN / CrAlN / TiAlN composite multilayer with a periodic modulation structure. The preparation process is simple, the thickness design is reasonable, the coating has a low coefficient of thermal expansion, low internal stress, and the bonding strength of the coating is greatly improved.

[0041] (2) The composite multilayer CrN layer and CrN base layer prepared by the present invention have good bonding force with the substrate, which can effectively prevent the expansion of fatigue-induced cracks between the substrate and the coating, thereby extending the service life of the substrate.

[0042] (3) Compared with other ordinary multilayer coatings, the CrAlN layer in the composite multilayer prepared by the present invention can block TiO2 from causing crack propagation and can improve the adhesion and thermal stability of the film substrate.

[0043] (4) Compared with other ordinary multilayer coatings, the CrAlN layer and TiAlN layer in the composite multilayer prepared by the present invention have similar lattice parameters, forming a coherent effect, which improves the mechanical properties of the coating.

[0044] (5) The composite multilayer TiAlN layer prepared by the present invention has the characteristics of corrosion resistance, high hardness and high wear resistance, which effectively protects the surface from corrosion and wear and improves the anti-friction performance of the coating.

[0045] (6) The CrN / CrAlN / TiAlN composite multilayer of the present invention has a periodic modulation structure, which increases the coating hardness, reduces internal stress, and improves the coating's oxidation resistance.

[0046] (7) The TiAlN layer in the previous period composite multilayer prepared by the present invention and the CrN layer in the next period composite multilayer have different physicochemical properties. They have strong bonding force, which can effectively enhance the overall performance of the coating and prevent the coating from peeling off under friction, wear or corrosion environment. Attached Figure Description

[0047] Figure 1 This is a schematic diagram of the CrN / CrAlN / TiAlN nanolayer structure in an embodiment of the present invention;

[0048] Figure 2 These are comparison images of the oxidation depth of the coating samples in the embodiments and comparative examples of the present invention;

[0049] Figure 3 This is a comparison diagram of the oxidation depth of the coating samples in the embodiments and comparative examples of the present invention.

[0050] Explanation of markings in the diagram:

[0051] 1—Matrix, 2—CrN underlayer, 3—CrN layer, 4—CrAlN layer, 5—TiAlN layer. Detailed Implementation

[0052] 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.

[0053] 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.

[0054] Example:

[0055] A CrN / CrAlN / TiAlN nanolayered coating, such as Figure 1 As shown, the substrate 1 includes a CrN base layer 2, a CrN layer 3, a CrAlN layer 4, and a TiAlN layer 5, which are sequentially deposited on the surface of the substrate 1. The thickness of the CrN base layer 2 is 300 nm, the thickness of the CrN layer 3 is 5 nm, the thickness of the CrAlN layer 4 is 6 nm, and the thickness of the TiAlN layer 5 is 4 nm.

[0056] The above-mentioned method for preparing CrN / CrAlN / TiAlN nanolayers involves magnetron sputtering using Cr, CrAl alloy, and TiAl alloy targets as sputtering targets to prepare CrN / CrAlN / TiAlN nanolayers on the surface of substrate 1. The specific steps are as follows:

[0057] S1. Pretreatment of substrate 1: Substrate 1 is made of 304 stainless steel with dimensions of 20×20×5mm. The acetone solution is a solution with a concentration of 80% prepared by 5L acetone and 1L distilled water. Substrate 1 is placed in the acetone solution and ultrasonically cleaned at 30kHz for 20min. Then it is immersed in 95% aqueous ethanol for 6min and then dried with an air gun.

[0058] S2. Target cleaning: Introduce argon gas at 210 sccm. Clean the Cr target, CrAl target and TiAl target in sequence against the baffle for 10 minutes under a current of 130A to remove impurities from the target surface.

[0059] S3, Substrate 1 treatment: Argon gas at 200 sccm was introduced, the vacuum degree was 3.5 Pa, the temperature was 400℃, and substrate 1 was etched using a Cr target with a bias voltage of -800V, a Cr target power of 120W, and a time of 15min.

[0060] S4, CrN underlayer 2 preparation: Nitrogen gas at 200 sccm was introduced, the vacuum degree was 3.5 Pa, the temperature was 400℃, Cr target was used for deposition, the deposition bias voltage was -110V, the Cr target power was 300W, the time was 30min, and a 300nm CrN underlayer 2 was obtained on substrate 1.

[0061] Preparation of S5 and CrN layer 3: Nitrogen gas was introduced at 200 sccm, the vacuum degree was 3.5 Pa, the temperature was 400℃, and Cr target was used for deposition. The deposition bias voltage was -110V, the Cr target power was 130W, the Cr atomic percentage content was 99.90%, and the time was 2.5 min. A 5 nm CrN layer 3 was obtained on the CrN base layer 2.

[0062] Preparation of S6 and CrAlN layer 4: Nitrogen gas was introduced at 200 sccm, the vacuum degree was 3.5 Pa, the temperature was 400℃, and CrAl target was used for deposition. The deposition bias voltage was -110V, the CrAl target power was 130W, the Cr atomic percentage content was 29.90%, the Al atomic percentage content was 70.10%, and the time was 3 min. A 6 nm CrAlN layer 4 was obtained on CrN layer 3.

[0063] S7, Preparation of TiAlN layer 5: Nitrogen gas was introduced at 200 sccm, the vacuum degree was 3.5 Pa, the temperature was 400℃, and TiAl target was used for deposition. The deposition bias voltage was -110V, the TiAl target power was 130W, the Ti atomic percentage content was 32.90%, the Al atomic percentage content was 67.10%, and the time was 2 min. A 4 nm TiAlN layer 5 was obtained on CrAlN layer 4.

[0064] Comparative Example 1:

[0065] A CrAlN nanocoating and its preparation method are basically the same as those in Example 1, except that only a 300 nm CrN underlayer 2 and a 15 nm CrAlN layer 4 are deposited.

[0066] Comparative Example 2:

[0067] A TiAlN nanocoating and its preparation method are basically the same as those in Example 1, except that only a 300 nm CrN underlayer 2 and a 15 nm TiAlN layer 5 are deposited.

[0068] An oxidation depth test of a coated sample, the specific steps of which are as follows:

[0069] Oxidation depth experiments were conducted on the examples and Comparative Examples 1 and 2. The three coated samples were placed in the same high-temperature oxidation furnace. The temperature was first raised from room temperature to 450°C for 60 minutes at a rate of 7.1°C / min, and held for 10 minutes. Then, the temperature was raised from 450°C to 800°C for 70 minutes at a rate of 5°C / min. Finally, the temperature was raised from 800°C to 1000°C for 40 minutes at a rate of 5°C / min. After holding at 1000°C for 2 hours, the furnace was cooled down for 200 minutes at a rate of 4.9°C / min. The oxidation depth of the three coated samples was compared after cooling to room temperature.

[0070] like Figure 2 As shown, in an environment of 1000℃, Comparative Examples 1 and 2 were completely oxidized, with the oxidized portion accounting for 100% of the total coating thickness. In contrast, the oxidized portion in the example accounted for 75% of the total coating thickness, which is 25% less than the oxidation depth percentage in the comparative examples. This indicates that the CrN / CrAlN / TiAlN nano-multilayer coating in the example exhibits better oxidation resistance.

[0071] A machinability test of a coated sample, the specific steps of which are as follows:

[0072] A YG6X carbide end mill was used as the substrate 1. The substrate 1 was first cleaned and etched, and the target material was cleaned. Then, magnetron sputtering deposition technology was used to deposit a CrN underlayer 2 and a multi-cycle coating with alternating "CrN layer 3-CrAlN layer 4-TiAlN layer 5" as the modulation cycle on the surface of the substrate 1. After 600 cycles, the CrN / CrAlN / TiAlN nano-multilayer coating sample of the embodiment was obtained. Comparative Examples 1 and 2 and their preparation methods are basically the same. The difference of Comparative Example 1 is that only the CrN underlayer 2 and CrAlN layer 4 are deposited on the surface of the substrate 1, and the difference of Comparative Example 2 is that only the CrN underlayer 2 and TiAlN layer 5 are deposited on the surface of the substrate 1.

[0073] Machinability tests were conducted on the examples and comparative examples 1 and 2, respectively. The cutting conditions and results are shown in Table 1.

[0074] Table 1 Comparison of machinability of coated samples in the examples and comparative examples

[0075]

[0076] As shown in Table 1, the service life of the coating in Comparative Example 1 is 15 min, the service life of the coating in Comparative Example 2 is 12 min, and the service life of the coating in the embodiment is 20 min. It can be seen that the CrN / CrAlN / TiAlN nano-multilayer coating in the embodiment has better cutting performance.

[0077] A nanoindentation experiment on a coated sample, the specific steps of which are as follows:

[0078] Using stainless steel as the substrate 1, the surface of substrate 1 is first polished to remove oxides or dust, followed by cleaning and etching. Then, magnetron sputtering deposition technology is used to deposit a CrN underlayer 2 and a multi-period coating with alternating "CrN layer 3-CrAlN layer 4-TiAlN layer 5" on the surface of the stainless steel substrate 1, resulting in the CrN / CrAlN / TiAlN nano-multilayer coating sample of the embodiment. Comparative Examples 1 and 2 and their preparation methods are basically the same. The difference in Comparative Example 1 is that only the CrN underlayer 2 and CrAlN layer 4 are deposited on the surface of the stainless steel substrate 1, and the difference in Comparative Example 2 is that only the CrN underlayer 2 and TiAlN layer 5 are deposited on the surface of the stainless steel substrate 1.

[0079] Nanoindentation experiments were conducted on the examples and comparative examples 1 and 2. Three types of coated samples were selected, and the indentation depth was controlled at 1 / 10 to 1 / 5 of the coating thickness. The experimental parameters were as follows: a Berkovich diamond indenter nanohardness tester, a fixed indentation depth of 50 nm, and a loading time of 6 s. Five repeated experiments were conducted on different parts of the same coated sample, and the average value was taken.

[0080] like Figure 3 As shown, the hardness of the coating in Comparative Example 1 is 31.3 GPa, the hardness of the coating in Comparative Example 2 is 28.4 GPa, and the hardness of the coating in the embodiment is 33.2 GPa. Therefore, it can be seen that the CrN / CrAlN / TiAlN nano-multilayer coating in the embodiment has higher hardness.

[0081] 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 CrN / CrAlN / TiAlN nanolayer, characterized in that, The nanomultilayer comprises a CrN base layer (2) sequentially deposited on the surface of a substrate (1) and a CrN / CrAlN / TiAlN composite multilayer with a periodic modulation structure. One period of the CrN / CrAlN / TiAlN composite multilayer includes an innermost CrN layer (3), a transition layer CrAlN layer (4), and an outermost TiAlN layer (5). When the CrN / CrAlN / TiAlN composite multilayer uses one period, the total thickness of the nanomultilayer is 269~315 nm, and the number of periods of the CrN / CrAlN / TiAlN composite multilayer is 1~600. The thickness of the CrN base layer (2) is 260~300 nm, and the total thickness of the CrN / CrAlN / TiAlN composite multilayer in one cycle is 9~15 nm; The thickness of the CrN layer (3) is 3~5 nm, the thickness of the CrAlN layer (4) is 4~6 nm, and the thickness of the TiAlN layer (5) is 2~4 nm. The substrate (1) is etched, and a CrN base layer (2) and a CrN / CrAlN / TiAlN composite multilayer with a periodic modulation structure are deposited. The preparation process is simple, the thickness design is reasonable, the coating has a low thermal expansion coefficient, low internal stress, and the bonding strength of the coating is greatly improved. The prepared composite multilayer has good bonding force between the CrN layer (3), the CrN underlayer (2) and the substrate (1), preventing the expansion of fatigue-induced cracks between the substrate (1) and the coating, thereby extending the service life of the substrate (1). The prepared composite multilayer CrAlN layer (4) blocks TiO2 from causing crack propagation, and improves the adhesion and thermal stability of the film substrate; The CrAlN layer (4) and TiAlN layer (5) in the prepared composite multilayer have similar lattice parameters, forming a coherent effect that improves the mechanical properties of the coating. The CrN / CrAlN / TiAlN composite multilayer has a periodically modulated structure, which increases the coating hardness, reduces internal stress, and improves the coating's oxidation resistance. The TiAlN layer (5) in the previous period of composite multilayer and the CrN layer (3) in the next period of composite multilayer have different physicochemical properties. They have a strong bond, which enhances the overall performance of the coating and prevents the coating from peeling off under friction, wear or corrosion.

2. A method for preparing CrN / CrAlN / TiAlN nanolayers as described in claim 1, characterized in that, The method includes the following steps: S1, Pretreatment of substrate (1): Cleaning substrate (1); S2. Target cleaning: Inert gas is introduced to clean Cr target, CrAl target and TiAl target; S3, Substrate (1) treatment: Inert gas is introduced and Cr target is used to etch the substrate (1). S4, CrN underlayer (2) preparation: The reaction gas is introduced and Cr target is used for deposition to obtain CrN underlayer (2). S5, CrN layer (3) preparation: The reaction gas was introduced and Cr target was used for deposition to obtain CrN layer (3); S6, CrAlN layer (4) preparation: The reaction gas was introduced and CrAl target was used for deposition to obtain CrAlN layer (4). S7, Preparation of TiAlN layer (5): The reaction gas is introduced and TiAl target is used for deposition to obtain TiAlN layer (5).

3. The method for preparing CrN / CrAlN / TiAlN nanolayers according to claim 2, characterized in that, In step S2, the flow rate of the inert gas is 150~210 sccm; The current for cleaning Cr, CrAl, and TiAl targets was 100~130 A, and the time was 10~15 min.

4. The method for preparing CrN / CrAlN / TiAlN nanolayers according to claim 2, characterized in that, In step S3, the flow rate of the inert gas is 150~210 sccm, the vacuum degree is 3.0~5.2 Pa, and the temperature is 350~450 ℃; The etching bias voltage is -850~-750 V, the Cr target power is 100~120 W, and the etching time is 10~15 min.

5. The method for preparing CrN / CrAlN / TiAlN nanolayers according to claim 2, characterized in that, In step S4, the reactant gas is nitrogen, with a flow rate of 160~200 sccm, a vacuum degree of 3.0~5.2 Pa, and a temperature of 350~450 ℃; The deposition bias voltage was -115 to -75 V, the Cr target power was 260 to 320 W, and the deposition time was 26 to 30 min.

6. The method for preparing CrN / CrAlN / TiAlN nanolayers according to claim 2, characterized in that, In step S5, the reactant gas is nitrogen, with a flow rate of 160~200 sccm, a vacuum degree of 3.0~5.2 Pa, and a temperature of 350~450 ℃; The deposition bias voltage was -115 to -75 V, the Cr target power was 100 to 160 W, the Cr atomic percentage content was 99.80 to 99.99%, and the deposition time was 1.5 to 2.5 min.

7. The method for preparing CrN / CrAlN / TiAlN nanolayers according to claim 2, characterized in that, In step S6, the reactant gas is nitrogen, with a flow rate of 160~200 sccm, a vacuum degree of 3.0~5.2 Pa, and a temperature of 350~450 ℃; The deposition bias voltage was -115 to -75 V, the CrAl target power was 100 to 160 W, the Cr atomic percentage content was 28 to 32%, the Al atomic percentage content was 68 to 72%, and the deposition time was 2 to 3 min.

8. The method for preparing CrN / CrAlN / TiAlN nanolayers according to claim 2, characterized in that, In step S7, the reaction gas is nitrogen, with a flow rate of 160~200 sccm, a vacuum degree of 3.0~5.2 Pa, and a temperature of 350~450 ℃; The deposition bias voltage was -115 to -75 V, the TiAl target power was 100 to 160 W, the Ti atomic percentage content was 32 to 34%, the Al atomic percentage content was 66 to 68%, and the deposition time was 1 to 2 min.

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