A PVD-Teflon composite coating and its preparation method and application

Abstract

The present invention relates to the technical field of composite coatings, and more specifically, to a PVD-Teflon composite coating and a preparation method and application thereof, wherein the PVD-Teflon composite coating comprises a PVD bottom layer, an intermediate layer and a Teflon layer which are arranged in sequence; the PVD bottom layer is a metal nitride, a metal carbide or a metal carbonitride, and the intermediate layer is a metal carbonitride. The present invention sequentially constructs a composite structure of a PVD bottom layer, a carbonitride intermediate layer and a Teflon self-lubricating surface layer on the surface of a substrate through arc ion plating (physical vapor deposition) and spraying composite technology, and the composite coating has both wear resistance and anti-adhesion properties, and has a wide range of application prospects in extruded products.

Description

Technical Field

[0001] The present invention relates to the technical field of composite coatings, and more specifically to a PVD-Teflon composite coating and a preparation method and application thereof. Background Art

[0002] Plastics are widely used in human life. However, during the manufacturing process of plastic products, they are prone to strong friction with the discharge mold, resulting in adhesion, which in turn affects the surface quality of the product and reduces the product quality.

[0003] Teflon has excellent anti-stick properties and has been widely used to improve the anti-stick properties of the surface of extrusion molds. However, during the service life of Teflon extrusion molds, the Teflon coating is prone to wear and tear, and the service life is extremely short.

[0004] PVD nitride coating has high hardness and wear resistance, and has high bonding strength with steel substrates, and has been widely used in surface strengthening treatment of various types of tools, molds, spare parts, etc. However, the surface of the extrusion mold with PVD nitride coating shows strong plastic bonding and poor service performance, which cannot meet the requirements. Summary of the invention

[0005] The purpose of the present invention is to provide a PVD-Teflon composite coating and a preparation method and application thereof, so as to solve the problems existing in the above-mentioned prior art and overcome the performance defects of single Teflon and PVD coatings.

[0006] To achieve the above object, the present invention provides the following solutions:

[0007] One of the technical solutions of the present invention is to provide a PVD-Teflon composite coating, comprising a PVD bottom layer, an intermediate layer and a Teflon layer arranged in sequence; the PVD bottom layer is a metal nitride, a metal carbide or a metal nitride carbonide, and the intermediate layer is a metal nitride carbon compound.

[0008] In the technical solution of the present invention, the PVD bottom layer is connected to the substrate, and has a high affinity with the substrate, which can ensure the bonding force between the PVD coating and the substrate; the middle layer connects the PVD bottom layer and the Teflon layer, and by regulating the carbon source flow rate during the deposition of the middle layer, a certain amount of amorphous carbon is precipitated in the middle layer, and the carbon has a high affinity with Teflon, thereby improving the bonding behavior between the Teflon layer and the middle layer, obtaining a high interlayer bonding force to adjust the interface stress, and then improving the bonding force and bearing capacity of the Teflon layer coating with the substrate; the Teflon layer is coated on the surface of the middle layer, has self-lubrication and strong anti-adhesion characteristics, and can improve the anti-adhesion performance of the composite coating. Through the synergistic effect of the PVD coating and the Teflon layer, a PVD-Teflon composite coating with high bonding force, wear resistance and anti-adhesion is finally obtained.

[0009] Furthermore, the PVD bottom layer is metal nitride.

[0010] Furthermore, the PVD bottom layer is AlCrN, AlTiN or AlCrCN; and the middle layer is AlCrNC, TiCN or TiSiCN.

[0011] Furthermore, the PVD bottom layer has a thickness of 0.5 to 10.0 μm, the middle layer has a thickness of 0.2 to 5.0 μm, and the Teflon layer has a thickness of 20 to 500 μm.

[0012] Furthermore, the thickness of the PVD bottom layer is 2.0-5.0 μm, the thickness of the middle layer is 0.2-3.0 μm, and the thickness of the Teflon layer is 30-150 μm.

[0013] The present invention finds that the coating thickness and organizational structure affect the wear resistance and anti-adhesion performance of the composite coating. Specifically, the present invention adopts a PVD bottom layer to obtain a high coating bonding force. If the PVD bottom layer is too thin, the process control difficulty increases and the improvement effect is poor; if the PVD bottom layer is too thick, the internal stress of the coating is extremely large, and the bonding force between the PVD bottom layer and the substrate deteriorates sharply. The middle layer is used to improve the affinity between it and the Teflon layer and obtain a high interlayer bonding force. However, if the middle layer is too thin, the improvement effect is poor; if it is too thick, the internal stress of the nitrogen-carbon compound layer is extremely high and it is easy to crack. If the Teflon layer is too thin, the wear resistance is poor, and if it is too thick, the interface between the middle layer and the Teflon layer is prone to interface stress concentration, and the Teflon layer peels off. In addition, the deposition order of the PVD bottom layer and the nitrogen-carbon compound layer is also related. Metal nitrides and metal carbides have poor affinity with Teflon and poor interlayer bonding force. Therefore, the thickness and combination order of the PVD bottom layer, the middle layer and the Teflon layer need to be reasonably regulated.

[0014] Furthermore, the carbon concentration in the intermediate layer is a gradient change or a constant value. Specifically, the gradient change is formed by starting the intermediate layer with an acetylene concentration of 0 and ending with an acetylene flow rate of 10 to 50 sccm, and the constant value is formed by directly introducing a constant flow rate (10 to 50 sccm) of acetylene during the deposition process.

[0015] The second technical solution of the present invention is a method for preparing the above-mentioned PVD-Teflon composite coating, comprising the following steps:

[0016] Using a metal target, nitrogen or a mixture of nitrogen and a carbon-containing gas source is introduced to perform physical vapor deposition on the substrate surface to prepare a PVD bottom layer;

[0017] Using a metal target, a mixture of nitrogen and a carbon-containing gas source is introduced to physically vapor deposit an intermediate layer on the surface of the PVD bottom layer;

[0018] A Teflon layer is sprayed on the surface of the middle layer.

[0019] Furthermore, the substrate is a steel substrate, an aluminum alloy, a titanium alloy or a hard alloy; the substrate is ultrasonically degreased, degreased, cleaned and dried before use.

[0020] Furthermore, an arc ion plating device is used to perform physical vapor deposition on the substrate surface to prepare a PVD bottom layer. The specific parameters include: metal target current 120-200A, nitrogen flow rate 300-800sccm, carbon-containing gas source flow rate 0-50sccm, applied substrate bias -40--100V, control the workpiece rotating rack speed in the furnace to 2.0-5.0rpm, deposition temperature 400-550°C, and deposition time 10-180min.

[0021] Furthermore, an arc ion plating device is used to perform physical vapor deposition of an intermediate layer on the surface of the PVD bottom layer, and specific parameters include: a metal target current of 120 to 200 A, a mixed gas flow rate of 500 to 800 sccm, an applied substrate bias of -40 to -100 V, a control of the workpiece rotating rack speed in the furnace to 2.0 to 5.0 rpm, a deposition temperature of 400 to 550° C., and a deposition time of 10 to 180 min; the mixed gas is a nitrogen and acetylene mixed gas, wherein the acetylene flow rate is a constant 10 to 50 sccm or the acetylene flow rate increases gradually from 0 sccm to 10 to 50 sccm during the physical vapor deposition process.

[0022] Furthermore, the process of spraying the Teflon layer on the surface of the intermediate layer specifically includes: first spraying the Teflon primer, baking at 120-180°C to obtain a primer layer of 10-50 μm, then cooling the furnace to 60-80°C and taking it out of the furnace, then spraying the Teflon topcoat, baking at 400-470°C to obtain a topcoat layer of 10-450 μm, and the primer layer and the topcoat layer constitute the Teflon layer.

[0023] Furthermore, in the process of spraying the Teflon layer on the surface of the intermediate layer, a spray gun is used, the distance between the nozzle and the workpiece is 25 cm, the movement speed of the spray gun is adjusted within 40 cm / s, the Teflon primer is 953G-506 type coating, and the Teflon topcoat is 953G-401 type coating.

[0024] The third technical solution of the present invention is the application of the above-mentioned PVD-Teflon composite coating in an extrusion mold.

[0025] The present invention discloses the following technical effects:

[0026] The present invention utilizes the high affinity between the PVD bottom layer and the substrate to ensure the bonding force between the PVD coating and the substrate; in the middle layer, by adjusting the carbon content, carbon (amorphous carbon or diamond) is precipitated in the nitrogen-carbon compound layer, and carbon has a high affinity with Teflon, thereby improving the bonding behavior between the Teflon layer and the nitrogen-carbon compound layer and obtaining a high interlayer bonding force; utilizing the self-lubricating and strong anti-adhesive properties of the Teflon layer to improve the anti-adhesive performance of the composite coating. By coordinating the PVD coating and the Teflon layer, an anti-adhesive and wear-resistant composite coating is finally obtained.

[0027] The present invention uses arc ion plating (physical vapor deposition) and spraying composite technology to sequentially construct a composite structure of a PVD bottom layer, a nitrogen-carbon compound middle layer and a Teflon self-lubricating surface layer on the substrate surface. The composite coating has both wear resistance and anti-adhesion properties and has broad application prospects in extruded products. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0029] Figure 1 This is a schematic diagram of the cross-sectional structure of the PVD-Teflon composite coating of Example 1.

[0030] Figure 2 This is the physical product of the PVD-Teflon composite coating of Example 1. DETAILED DESCRIPTION

[0031] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0032] It should be understood that the terms described in the present invention are only for describing a particular embodiment and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. The intermediate value in any stated value or stated range, and each smaller range between any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0033] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0034] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to those skilled in the art. The present invention description and examples are exemplary only.

[0035] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0036] The target materials used in the following embodiments of the present invention are all commercially available products, specifically: AlCr target, wherein the Al content is 70 at.%, and the Cr content is 30 at.%.

[0037] Example 1

[0038] This embodiment provides a PVD-Teflon composite coating, comprising a PVD bottom layer, a nitrogen-carbon compound middle layer and a Teflon surface self-lubricating layer sequentially arranged on the surface of a substrate, wherein the PVD bottom layer is connected to a metal substrate (commercially available 40Cr steel).

[0039] A method for preparing a PVD-Teflon composite coating, the specific steps are as follows:

[0040] S1: ultrasonically degreasing, degreasing, cleaning and drying the substrate;

[0041] S2: Using arc ion plating equipment, control the metal target (AlCr target) current to 160A, nitrogen flow rate to 500sccm, acetylene flow rate to 0sccm, apply substrate bias voltage -60V, control the workpiece rotating rack speed in the furnace to 3.5rpm, deposit on the substrate surface at 450℃ for 60min, and obtain AlCrN bottom layer with a thickness of 3.0μm;

[0042] S3: Control the current of the metal target (AlCr target) to 160A, introduce a mixed gas of nitrogen and acetylene (carbon source), the nitrogen flow rate is 500sccm, the acetylene initial flow rate is 0sccm and the final flow rate is 20sccm, the acetylene step length is 0.67sccm / min, the substrate bias voltage is -60V, the deposition time is 30min, the workpiece rotating rack speed in the furnace is controlled to be 3.5rpm, and a nitrogen-carbon compound layer with a thickness of 1.5μm is deposited on the surface of the AlCrN bottom layer using the AlCr target at 450℃. At this point, the AlCrN-AlCrCN layer is obtained;

[0043] S4: The AlCrN-AlCrCN layer sample is subjected to deoiling, degreasing, ultrasonic cleaning, and blown dry. Then, using a spray gun, the distance between the nozzle and the workpiece is 25 cm, and the spray gun moves at a speed of 40 cm / s, 953G-506 paint is sprayed on the surface of the PVD coating, and then placed in a 150°C furnace for baking and hardening to obtain a primer with a thickness of 20μm; then the furnace is cooled to 70°C and taken out of the furnace, and then 953G-401 type paint is sprayed and dried, and then heated to 440°C in the furnace for baking for 20 minutes to obtain a Teflon layer with a thickness of 50μm. At this point, an AlCrN-AlCrCN-Teflon composite coating is obtained with a total thickness of 74.5μm.

[0044] Embodiments 2 to 7

[0045] The preparation method of the PVD-Teflon composite coating of Examples 2 to 7 comprises the following steps:

[0046] S1: same as Example 1;

[0047] S2: As in Example 1, an AlCrN or AlCrCN bottom layer is prepared on 40Cr steel using an arc ion plating device, except that the experimental parameters are shown in Table 1:

[0048] Table 1

[0049]

[0050] S3: As in Example 1, an AlCrCN layer is prepared on the AlCrN bottom layer or the AlCrCN bottom layer to obtain an AlCrN-AlCrCN layer or an AlCrCN-AlCrCN layer, except that the experimental parameters of Examples 2 to 7 are shown in Table 2:

[0051] Table 2

[0052]

[0053] S4: As in Example 1, a Teflon layer is prepared on the AlCrN-AlCrCN layer or the AlCrCN-AlCrCN layer, to obtain an AlCrN-AlCrCN-Teflon composite coating or an AlCrCN-AlCrCN-Teflon composite coating, except that the experimental parameters of Examples 2 to 7 are shown in Table 3:

[0054] Table 3

[0055]

[0056]

[0057] After the above treatment, AlCrN-AlCrCN-Teflon composite coatings or AlCrCN-AlCrCN-Teflon composite coatings with different coating thicknesses as shown in Table 4 were obtained;

[0058] Table 4

[0059] Coating thickness of composite coating / μm Example 2 111.5 (AlCrN-AlCrCN-Teflon composite coating) Example 3 103.5 (AlCrN-AlCrCN-Teflon composite coating) Example 4 80.5 (AlCrN-AlCrCN-Teflon composite coating) Example 5 80.5 (AlCrN-AlCrCN-Teflon composite coating) Example 6 74.1 (AlCrN-AlCrCN-Teflon composite coating) Example 7 74.5 (AlCrCN-AlCrCN-Teflon composite coating)

[0060] Comparative Example 1

[0061] This comparative example provides an AlCrN layer, and the preparation method thereof comprises the following steps:

[0062] S1: Ultrasonic degreasing, degreasing, cleaning and drying of 40Cr steel;

[0063] S2: Using arc ion plating equipment, control the metal target (AlCr target) current to 160A, the nitrogen flow rate to 500sccm, the acetylene flow rate to 0sccm, apply a substrate bias of -60V, control the workpiece rotating speed in the furnace to 3.5rpm, and deposit on the substrate surface at 450℃ for 60min to obtain an AlCrN bottom layer with a thickness of 3.0μm.

[0064] Comparative Example 2

[0065] This comparative example provides an AlCrCN layer, and the preparation method thereof comprises the following steps:

[0066] S1: Ultrasonic degreasing, degreasing, cleaning and drying of 40Cr steel;

[0067] S2: The current of the metal target (AlCr target) was controlled to be 160A, and a mixed gas of nitrogen and acetylene (carbon source) was introduced. The nitrogen gas flow rate was 500sccm, the initial acetylene flow rate was 0sccm and the final flow rate was 20sccm, the acetylene step length was 0.67sccm / min, the substrate bias was -60V, the deposition time was 30min, the workpiece rotating rack speed in the furnace was controlled to be 3.5rpm, and a nitrogen-carbon compound layer with a thickness of 1.5μm was deposited on the surface of the AlCrN bottom layer using an AlCr target at 450℃.

[0068] Comparative Example 3

[0069] This comparative example provides a Teflon layer, and its preparation method comprises the following steps:

[0070] S1: Ultrasonic degreasing, degreasing, cleaning and drying of 40Cr steel;

[0071] S2: Use a spray gun with a nozzle distance of 25 cm from the workpiece and a spray gun moving speed of 40 cm / s to spray 953G-506 paint on the surface of the PVD coating, then put it into a 150°C furnace for baking and hardening to obtain a primer with a thickness of 20 μm; then cool the furnace to 70°C and take it out of the furnace, then spray 953G-401 paint and dry it, then heat it to 440°C in the furnace and bake it for 20 minutes to obtain a Teflon layer with a thickness of 50 μm. At this point, a Teflon composite coating with a total thickness of 70 μm is obtained.

[0072] Comparative Example 4

[0073] This comparative example provides an AlCrN-AlCrCN layer, and the preparation method thereof comprises the following steps:

[0074] S1: Ultrasonic degreasing, degreasing, cleaning and drying of 40Cr steel;

[0075] S2: Using arc ion plating equipment, control the metal target (AlCr target) current to 160A, nitrogen flow rate to 500sccm, acetylene flow rate to 0sccm, apply substrate bias voltage -60V, control the workpiece rotating rack speed in the furnace to 3.5rpm, deposit on the substrate surface at 450℃ for 60min, and obtain AlCrN bottom layer with a thickness of 3.0μm;

[0076] S3: Control the current of the metal target (AlCr target) to 160A, introduce a mixed gas of nitrogen and acetylene (carbon source), the nitrogen gas flow rate is 500sccm, the acetylene initial flow rate is 0sccm and the final flow rate is 20sccm, the acetylene step length is 0.67sccm / min, the substrate bias voltage is -60V, the deposition time is 30min, the workpiece rotating rack speed in the furnace is controlled to be 3.5rpm, and a nitrogen-carbon compound layer with a thickness of 1.5μm is deposited on the surface of the AlCrN bottom layer using the AlCr target at 450℃. So far, an AlCrN-AlCrCN layer with a total thickness of 4.5μm is obtained.

[0077] Comparative Example 5

[0078] This comparative example provides an AlCrN-Teflon layer, comprising an AlCrN bottom layer and a Teflon self-lubricating surface layer connected in sequence, and a preparation method thereof comprises the following steps:

[0079] S1: Ultrasonic degreasing, degreasing, cleaning and drying of 40Cr steel;

[0080] S2: Using arc ion plating equipment, control the metal target (AlCr target) current to 160A, nitrogen flow rate to 500sccm, acetylene flow rate to 0sccm, apply substrate bias voltage -60V, control the workpiece rotating rack speed in the furnace to 3.5rpm, deposit on the substrate surface at 450℃ for 60min, and obtain AlCrN bottom layer with a thickness of 3.0μm;

[0081] S2: Use a spray gun with a nozzle distance of 25 cm from the workpiece and a spray gun moving speed of 40 cm / s to spray 953G-506 paint on the surface of the AlCrN layer, then put it into a 150°C furnace for baking and hardening to obtain a primer with a thickness of 20 μm; then cool the furnace to 70°C and take it out of the furnace, then spray 953G-401 paint and dry it, then heat it to 440°C in the furnace and bake it for 20 minutes to obtain a Teflon layer with a thickness of 50 μm. At this point, an AlCrN-Teflon composite coating is obtained with a total thickness of 73 μm.

[0082] Comparative Example 6

[0083] This comparative example provides an AlCrN-Teflon-AlCrCN composite layer, comprising AlCrN, Teflon and AlCrCN layers connected in sequence, and a preparation method thereof comprises the following steps:

[0084] S1: Ultrasonic degreasing, degreasing, cleaning and drying of 40Cr steel;

[0085] S2: Using arc ion plating equipment, control the metal target (AlCr target) current to 160A, nitrogen flow rate to 500sccm, acetylene flow rate to 0sccm, apply substrate bias voltage -60V, control the workpiece rotating rack speed in the furnace to 3.5rpm, deposit on the substrate surface at 450℃ for 60min, and obtain AlCrN bottom layer with a thickness of 3.0μm;

[0086] S3: Use a spray gun with a nozzle distance of 25 cm from the workpiece and a spray gun moving speed of 40 cm / s to spray 953G-506 paint on the surface of the AlCrN layer, then put it into a 150°C furnace for baking and hardening to obtain a primer with a thickness of 20 μm; then cool the furnace to 70°C and take it out of the furnace, then spray 953G-401 paint and dry it, then heat it to 440°C in the furnace and bake it for 20 minutes to obtain a Teflon layer with a thickness of 50 μm. At this point, an AlCrN-Teflon composite coating is obtained;

[0087] S4: The current of the metal target (AlCr target) was controlled to be 160A, and a mixed gas of nitrogen and acetylene (carbon source) was introduced. The nitrogen gas flow rate was 500sccm, the initial acetylene flow rate was 0sccm and the final flow rate was 20sccm, the acetylene step length was 0.67sccm / min, the substrate bias was -60V, the deposition time was 30min, the workpiece rotating rack speed in the furnace was controlled to be 3.5rpm, and a nitrogen-carbon compound layer with a thickness of 1.5μm was deposited on the Teflon surface using the AlCr target at 450℃ to obtain an AlCrN-Teflon-AlCrCN composite layer with a thickness of 74.5μm.

[0088] Test example

[0089] The coatings prepared in the examples and comparative examples were tested for performance, and the specific method was as follows:

[0090] (1) Use a multifunctional scratch tester to test the bonding strength between the coating and the substrate, with a test load of 0 to 120N;

[0091] (2) The anti-adhesive properties of the coating were tested using a contact angle meter. The test temperature was room temperature. A drop of liquid was dropped onto the coating surface, left to stand for 2 minutes, and then the contact angle was measured.

[0092] (3) A room temperature friction and wear tester was used to test the wear resistance of each coating. The test load was 2 N, the rotation speed was 318 rpm, the time was 30 min, and the friction partner was a 40Cr steel ball with a diameter of 6 mm.

[0093] The test results are shown in Table 5-6.

[0094] Table 5

[0095]

[0096]

[0097] In Table 5, the PVD bottom layer is the thickness of the coating prepared in step S2, and the middle layer is the thickness of the coating prepared in step S3.

[0098] Table 6

[0099]

[0100] It can be seen from Tables 5 and 6 that the bonding force between the coating and the substrate of Examples 1 to 7 of the present invention is above 40N, the contact angle is greater than 165°, and the wear rate is less than 4.04×10 -5, which shows that the coating has high wear resistance and anti-adhesion properties. In Example 7, when the PVD bottom layer is AlCrCN, the other deposition processes are the same, and the coating adhesion and wear resistance are slightly reduced. The reason is that the internal stress of AlCrCN is large, so the coating is difficult to thicken and has poor resistance to external loads; the internal stress of the AlCrN coating is small. By coordinating the two layers, a thicker coating can be obtained. In comparison, the coatings of Comparative Examples 1 to 2 and Comparative Example 4 have excellent wear resistance, but poor anti-adhesion performance, and Comparative Examples 3 and 5 have good anti-adhesion effects, but poor wear resistance.

[0101] On the basis of the above contents, the present invention further prepares a PVD-Teflon composite coating in which the PVD bottom layer is AlCrN, AlTiN or AlCrCN; the middle layer is AlCrNC, TiCN or TiSiCN, and the PVD bottom layer, middle layer and Teflon layer are arranged in sequence. It is found that a composite coating with good anti-stickiness and wear resistance can be obtained.

[0102] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A PVD-Teflon composite coating, characterized in that: It is composed of a PVD bottom layer, an intermediate layer and a Teflon layer arranged in sequence; the PVD bottom layer is a metal nitride, and the intermediate layer is a metal nitrogen-carbon compound; The PVD bottom layer is AlCrN or AlTiN; the middle layer is AlCrNC, TiCN or TiSiCN; The thickness of the PVD bottom layer is 0.5 to 10.0 μm, the thickness of the intermediate layer is 0.2 to 5.0 μm, and the thickness of the Teflon layer is 20 to 500 μm; The Teflon layer is composed of a primer layer with a thickness of 10 to 50 μm and a topcoat layer with a thickness of 10 to 450 μm.

2. The PVD-Teflon composite coating according to claim 1, characterized in that: The carbon concentration of the metal nitrogen-carbon compound in the intermediate layer is a gradient change or a constant value.

3. A method for preparing a PVD-Teflon composite coating according to any one of claims 1 to 2, characterized in that: The following steps are involved: Using a metal target and introducing nitrogen, physical vapor deposition is performed on the substrate surface to prepare a PVD bottom layer; Using a metal target, a mixture of nitrogen and a carbon-containing gas source is introduced to physically vapor deposit an intermediate layer on the surface of the PVD bottom layer; A Teflon layer is sprayed on the surface of the middle layer.

4. The preparation method according to claim 3, characterized in that: The substrate is a steel substrate, an aluminum alloy, a titanium alloy or a hard alloy; the substrate is ultrasonically degreased, degreased, cleaned and dried before use.

5. The preparation method according to claim 3, characterized in that: The PVD bottom layer is prepared by physical vapor deposition on the substrate surface using arc ion plating equipment. The specific parameters include: metal target current 120~200A, nitrogen flow rate 300~800sccm, applied substrate bias -40~-100V, control of the workpiece rotating rack speed in the furnace at 2.0~5.0rpm, deposition temperature 400~550℃, and deposition time 10~180min.

6. The preparation method according to claim 3, characterized in that: An arc ion plating device is used to perform physical vapor deposition of an intermediate layer on the surface of a PVD bottom layer, and specific parameters include: a metal target current of 120 to 200 A, a mixed gas flow rate of 500 to 800 sccm, an applied substrate bias of -40 to -100 V, a control of a workpiece rotating rack speed in a furnace of 2.0 to 5.0 rpm, a deposition temperature of 400 to 550° C., and a deposition time of 10 to 180 min; the mixed gas is a nitrogen and acetylene mixed gas, wherein the acetylene flow rate is a constant 10 to 50 sccm or the acetylene flow rate increases gradually from 0 sccm to 10 to 50 sccm during the physical vapor deposition process.

7. The preparation method according to claim 3, characterized in that: The process of spraying the Teflon layer on the surface of the intermediate layer specifically includes: first spraying Teflon primer, baking at 120-180°C to obtain a primer layer of 10-50 μm, then spraying Teflon topcoat, baking at 400-470°C to obtain a topcoat layer of 10-450 μm, and the primer layer and the topcoat layer constitute the Teflon layer.

8. Use of the PVD-Teflon composite coating according to any one of claims 1 to 2 as an extrusion die coating or a spare parts coating.

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