Composite surface treatment process for valve parts and valve parts

Abstract

The present invention discloses a composite surface treatment process for valve parts and valve parts, wherein the surface treatment process is to process a 50-300 micron thick support layer on a cleaned substrate and after grinding and polishing, a PVD coating with a surface layer of a superhard carbon-based coating is processed on the support layer. The present invention uses a thicker support layer to provide support for the PVD coating, which can prevent the PVD coating, especially the superhard carbon-based coating, from failing due to substrate deformation. The hardness of the support layer is between the hardness of the substrate and the superhard carbon-based coating, which greatly avoids the problem of poor bonding between the substrate and the superhard carbon-based coating due to excessive hardness gradient. Further, the hardness of the superhard carbon-based coating is between 3500HV-6500HV, and the friction coefficient is between 0.06-0.1, which increases the surface hardness exponentially, and the surface has a low friction coefficient, which fully meets the use needs of high-pressure and high-frequency hard sealing occasions, and the service life is 3-10 times higher than that of valve parts processed by conventional processes.

Description

Technical Field

[0001] The invention relates to the technical field of surface modification, in particular to a composite surface treatment process for valve components and valve components. Background Art

[0002] At present, with the development of the valve industry, there are endless requirements to meet extremely harsh working conditions such as high pressure, high frequency switching, high-intensity hard particle impact, etc. Therefore, it is necessary to treat the surface of valve seats, valve cores, valve discs and other valve components to meet the use requirements of high pressure and high frequency hard sealing occasions with extremely high wear resistance requirements.

[0003] A Chinese patent application with application publication number CN109750249A discloses a carburizing heat treatment method for a valve core, wherein the hardness of the valve core surface obtained after the treatment is between HV10600-750 or HR 15N88-91, and the hardness thereof cannot meet the use requirements of higher hard sealing scenarios.

[0004] Of course, there are also surface modification methods such as electroplating, plasma surfacing, and laser cladding to improve the surface performance of valve components. However, after surface modification by these methods, the surface hardness of valve components cannot reach 1800HV. For application scenarios with higher hardness requirements and higher wear resistance, such as valves used for polysilicon powder transmission, the service life of valve components obtained by these surface modification processes cannot meet the expected requirements. Summary of the invention

[0005] The purpose of the present invention is to solve the above problems existing in the prior art and to provide a composite surface treatment process for valve components and valve components.

[0006] The purpose of the present invention is achieved through the following technical solutions:

[0007] The composite surface treatment process of valve parts includes the following steps:

[0008] S1, processing the surface of the substrate to obtain a support layer, wherein the thickness of the support layer is between 50 micrometers and 300 micrometers; and the hardness of the support layer is greater than the hardness of the substrate;

[0009] S2, grinding and polishing the support layer;

[0010] S3, a PVD coating is obtained on the polished supporting layer, wherein the surface layer of the PVD coating is an ultra-hard carbon-based coating, the hardness of the ultra-hard carbon-based coating is greater than the hardness of the supporting layer, the hardness range of the ultra-hard carbon-based coating is between 3500HV-6500HV, and the friction coefficient of the ultra-hard carbon-based coating is between 0.06-0.1.

[0011] Preferably, in the composite surface treatment process for valve components, the support layer is obtained by thermal spraying or surface heat treatment strengthening.

[0012] Preferably, in the composite surface treatment process for valve components, when the substrate is stainless steel, the support layer is a nickel-based alloy layer, a tungsten carbide layer or a chromium carbide layer obtained by thermal spraying.

[0013] Preferably, in the composite surface treatment process for valve components, when the substrate is a titanium alloy, the support layer is a nitriding layer or a carburizing layer or a carbonitriding layer or an oxygen permeating layer.

[0014] Preferably, in the composite surface treatment process for valve components, the hardness of the support layer ranges from 600 HV to 1800 HV.

[0015] Preferably, in the composite surface treatment process for valve components, S3 comprises the following steps:

[0016] S31, cleaning the substrate processed by S2;

[0017] S32, depositing a base layer on the cleaned support layer;

[0018] S33, depositing a transition layer on the bottom layer;

[0019] S34, depositing the superhard carbon-based coating on the transition layer.

[0020] Preferably, in the composite surface treatment process for valve components, the base layer and transition layer are deposited by a magnetron sputtering process; and the superhard carbon-based coating is deposited by an arc ion plating technique.

[0021] Preferably, in the composite surface treatment process for valve components, the content of diamond phase in the superhard carbon-based coating is not less than 70%.

[0022] Preferably, in the composite surface treatment process for valve components, the superhard carbon-based coating is a TaC coating.

[0023] Preferably, in the composite surface treatment process for valve components, the thickness of the superhard carbon-based coating is between 2 microns and 10 microns.

[0024] A valve component comprises a substrate, a surface of which is provided with a support layer, the hardness of the support layer being greater than the hardness of the substrate; the thickness of the support layer is between 50 microns and 300 microns; a PVD coating is provided on the support layer, the surface layer of the PVD coating is an ultra-hard carbon-based coating, the hardness of the ultra-hard carbon-based coating is greater than the hardness of the support layer, the hardness range of the ultra-hard carbon-based coating is between 3500HV and 6500HV, and the friction coefficient of the ultra-hard carbon-based coating is between 0.06 and 0.1.

[0025] The advantages of the technical solution of the present invention are mainly reflected in:

[0026] The present invention first forms a thicker support layer on the substrate. The thicker support layer can provide effective support for the PVD coating, can resist the deformation of the substrate, and effectively prevent the PVD coating, especially the super-hard carbon-based coating, from failing due to the deformation of the substrate. At the same time, the hardness of the support layer is between the hardness of the substrate and the super-hard carbon-based coating, which can achieve a smooth transition of the hardness gradient, thereby greatly avoiding the problem of poor bonding between the substrate and the super-hard carbon-based coating due to the excessive hardness gradient, and ensuring the bonding. Further, the hardness of the super-hard carbon-based coating is between 3500HV-6500HV, and the friction coefficient is between 0.06-0.1, which increases the surface hardness exponentially, and the surface has a low friction coefficient, which fully meets the use needs of high-pressure and high-frequency hard sealing occasions, and the service life is increased by 3-10 times relative to the valve core processed by conventional processes.

[0027] The ultra-hard carbon-based coating of the present invention adopts taC coating, in which the content of diamond phase is not less than 70%, which can effectively ensure that the ultra-hard carbon-based coating has ultra-high hardness and low friction coefficient, thereby meeting the long-term use requirements in high voltage, high frequency switching, and high-intensity hard particle impact scenarios.

[0028] The present invention adopts a combination of two processes in the cleaning process of the superhard carbon-based coating, which can effectively improve the etching cleaning quality and efficiency and lay a stable foundation for improving the bonding force between the support layer and the PVD coating. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 is a schematic diagram of a valve component of the present invention;

[0030] Figure 2 Schematic diagram of the anode layer ion source of the present invention. DETAILED DESCRIPTION

[0031] The purpose, advantages and features of the present invention will be illustrated and explained by the non-limiting description of the following preferred embodiments. These embodiments are only typical examples of the application of the technical solution of the present invention, and any technical solution formed by equivalent replacement or equivalent transformation falls within the scope of protection claimed by the present invention.

[0032] In the description of the scheme, it should be noted that the terms "center", "up", "down", "left", "right", "front", "back", "vertical", "horizontal", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings, and are only for the convenience of description and simplified description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance. Moreover, in the description of the scheme, with the operator as a reference, the direction close to the operator is the proximal end, and the direction away from the operator is the distal end.

[0033] The composite surface treatment process for valve components disclosed in the present invention is described below in conjunction with the accompanying drawings. The valve components may be valve flaps, ball valves, valve seats, etc. Of course, the composite surface treatment process may also be used for other components with the same surface requirements.

[0034] The composite surface treatment process comprises the following steps:

[0035] S1, processing the surface of the substrate 1 to obtain a support layer 2, wherein the thickness of the support layer 2 is between 50 micrometers and 300 micrometers; and the hardness of the support layer 2 is greater than the hardness of the substrate 1;

[0036] S2, grinding and polishing the support layer 2;

[0037] S3, a PVD coating 3 is obtained on the polished supporting layer 2, wherein the surface of the PVD coating is an ultra-hard carbon-based coating, the hardness of the ultra-hard carbon-based coating is greater than the hardness of the supporting layer 2, the hardness range of the ultra-hard carbon-based coating is between 3500HV-6500HV, and the friction coefficient (dry friction) of the ultra-hard carbon-based coating 33 is between 0.06-0.1.

[0038] According to the above method, the Figure 1 The valve component shown comprises a substrate 1 , a support layer 2 is provided on the surface of the substrate 1 , a PVD coating 3 is provided on the support layer 2 , and the surface layer of the PVD coating is a superhard carbon-based coating 33 .

[0039] The substrate 1 may be made of stainless steel or titanium alloy, etc., and has a relatively low hardness, usually between 100-600 HV.

[0040] In S1, the support layer 2 is obtained by thermal spraying or surface heat treatment strengthening. Specifically, when the substrate 1 is stainless steel, the support layer 2 is processed by thermal spraying, and the support layer 2 can be a nickel-based alloy or tungsten carbide or chromium carbide. When the substrate 1 is a titanium alloy, it is processed by nitriding process or carburizing process or carbonitriding process or oxygenation process, and correspondingly, the support layer 2 is or a nitriding layer or a carburizing layer or a carbonitriding layer or an oxygenation layer. Among them, thermal spraying, nitriding process, carburizing process, carbonitriding process and oxygenation process are known technologies and are not described in detail here.

[0041] Preferably, the hardness of the support layer 2 is in the range of 600HV-1800HV, and the thickness of the support layer 2 is in the range of 100 microns-300 microns, so that the support layer 2 can provide sufficient support force and realize hardness gradient transition at the same time, and improve the bonding strength between the superhard carbon-based coating 33 and the substrate 1. According to the VDI-3198 standard (Germany), the bonding strength between the superhard carbon-based coating 33 and the substrate 1 can reach the optimal HF1 level. At the same time, the thicker support layer 2 has a certain impact resistance, which can make up for the shortcomings of the superhard carbon-based coating 33 with high hardness but high brittleness, so that the high hardness and wear resistance of the superhard carbon-based coating 33 can be fully utilized, and at the same time, the bonding strength and impact resistance of the superhard carbon-based coating 33 are better than the film-based bonding strength and impact resistance of the superhard carbon-based coating 33 directly processed on the surface of the substrate 1.

[0042] The specific process of grinding and polishing the support layer in S2 is a known technology and is not an innovation of this solution, so it will not be described in detail here.

[0043] The S3 comprises the following steps:

[0044] S31, cleaning the substrate processed by S2;

[0045] S32, depositing a bottom layer 31 on the cleaned support layer;

[0046] S33, depositing a transition layer 32 on the bottom layer 31;

[0047] S34 , depositing the superhard carbon-based coating on the transition layer 32 .

[0048] In S31, the substrate treated in S2 may be cleaned by a known method. In this embodiment, a plasma cleaning process is used to clean the surface of the substrate 1. The plasma cleaning process may be a known cleaning method.

[0049] Preferably, the plasma cleaning process comprises the following steps:

[0050] S311, placing the workpiece on a workpiece holder in the vacuum chamber.

[0051] S312, evacuate the vacuum chamber to 0.05Pa.

[0052] S313, filling the vacuum chamber with argon gas so that the pressure in the vacuum chamber is between 0.6-10Pa, preferably between 0.6-1.5Pa.

[0053] S314, turn on the bias power supply and the ion beam source to realize bias glow cleaning and ion beam cleaning to clean the workpiece simultaneously. In the specific operation, first turn on the bias power supply, and then turn on the ion beam sources one by one. The voltage of the bias power supply is between 700-2000V, preferably between 800V-2000V. At this time, a large bias current (2-30A, preferably 15-30A) can be obtained, so as to achieve a better cleaning effect.

[0054] The voltage of the ion beam source during operation is between 300-2000 V, preferably between 1500 V-2000 V. The time for the bias glow cleaning and ion beam cleaning to clean the workpiece simultaneously is no more than 1 hour, preferably no more than 45 minutes, and most preferably about 30 minutes.

[0055] The bias current of the plasma of bias glow cleaning is large, which can achieve large-area cleaning. However, when this method is used to clean the surface of workpieces with complex shapes, the cleaning effect does not meet expectations due to the uneven distribution of the glow. Ion beam cleaning has the advantages of large plasma energy and directionality, but it has the disadvantages of small plasma bias current, long cleaning time, and low efficiency. After combining the two cleaning methods, the advantages of large-area and high-efficiency of bias glow cleaning effectively make up for the problems of small bias current and low efficiency of ion beam cleaning. At the same time, the large plasma energy and directionality of ion beam cleaning effectively make up for the defects of insufficient plasma energy of bias glow cleaning and the inability to perform high-quality cleaning of corner areas and anisotropic positions, achieving a perfect combination of cleaning effect and efficiency. In addition, a furnace of workpieces can be completely cleaned within half an hour, the cleaning time is greatly reduced, and the cleaning efficiency is greatly improved.

[0056] The ion beam sources arranged in the vacuum chamber are preferably anode layer ion sources, which are evenly distributed around the workpiece holder, so that ion beam cleaning in different angles can be achieved, thereby improving the effect of ion beam cleaning.

[0057] However, the working gas pressures required for ion beam cleaning and bias glow cleaning are different (the working gas pressure required for bias glow cleaning is between 0.7-10Pa. For anode layer ion beam cleaning, the working gas pressure required is between 0.1-0.4Pa).

[0058] In view of this, it is necessary to enable them to work synchronously under the same working air pressure:

[0059] The present invention is realized by changing the horizontal distance between the inner cathode 10 and the outer cathode 20 of the anode layer ion source and the distance between the cathode and cathode 30 in the height direction.

[0060] As attached Figure 2 As shown, like the known anode layer ion source, the anode layer ion source comprises an inner cathode 10 and an outer cathode 20 located at the periphery of the inner cathode 10, and an anode 30 is arranged in the gap just below the gap between the inner cathode 10 and the outer cathode 20. A magnet 40 is arranged just below the inner cathode 10 and located in the middle of the anode 30, and the magnet 40 is a permanent magnet.

[0061] The inventor has found that when the horizontal spacing L1 between the inner cathode and the outer cathode and the distance L2 between the cathode and the anode in the height direction are small, the inter-electrode spacing of the glow discharge is close, and when the voltage of the ion beam source is 1500V-2000V, it is easy to break down under high pressure, resulting in unstable operation. The present invention can increase the inter-electrode spacing of the glow discharge and effectively reduce the occurrence of arcing by setting the horizontal distance between the inner and outer cathodes between 4-8mm and the distance between the cathode and the anode in the height direction between 4-8mm, so that the ion beam can remain stable under higher pressure. Specifically, when the ion beam source works at a voltage of 1500V-2000V, the ion beam can work stably under a working pressure of less than 1.5Pa.

[0062] At the same time, the anode layer ion source is connected to a pulse power supply, and the duty cycle of the pulse power supply is controlled within 40% when it is working, which can effectively suppress the arcing phenomenon of the ion beam under high voltage 1500-2000V and high gas pressure 0.6-1.5Pa, so that the ion beam can work more stably under higher working pressure.

[0063] Although the adjustment of the above spacing enables the ion beam to work stably under a higher working gas pressure, it will also cause the ion energy to weaken, which affects the cleaning effect. Therefore, it is necessary to increase the ion energy, which is achieved by increasing the magnetic induction intensity of the magnet 40 of the anode layer ion source. The inventors further studied and determined that when the magnetic induction intensity of the magnet 40 is between 450-550 mT (milli-Tesla), the ion energy can achieve the expected effect. Through such a design, the two cleaning processes can be fully and effectively combined.

[0064] In the S32, the bottom layer 31 is preferably deposited by a magnetron sputtering process, and can be processed from known feasible materials, such as Cr (chromium) or Ti (titanium).

[0065] In S33, the transition layer 32 may be a carbide or nitride of the underlying material, for example, chromium nitride, chromium carbide, tungsten carbide, etc., which is also deposited by a magnetron sputtering process.

[0066] The specific process of depositing the bottom layer 31 and the transition layer 32 by magnetron sputtering is a known technology and will not be described in detail here.

[0067] In S34, the super-hard carbon-based coating 33 is deposited by arc ion plating technology. The super-hard carbon-based coating 33 is preferably a taC coating (tetrahedral amorphous carbon) with a thickness between 2 microns and 10 microns. In addition, the content of diamond phase in the super-hard carbon-based coating 33 is not less than 70%, and the rest is graphite phase. Its wear resistance is more than 10 times that of the supporting layer 2, and its hardness is about more than 2 times that of the supporting layer 2. Combined with a certain coating thickness, the service life of valve components can be effectively extended.

[0068] Arc ion plating technology is a known technology. In the specific preparation, the arc current is controlled at 40-80A, and the bias voltage is preferably between 50-500 V. Such process conditions can make the content of diamond phase in the final superhard carbon-based coating 33 as high as possible, so as to have better hardness.

[0069] Further, after deposition for a period of time, the power supply is turned off, and the vacuum degree in the vacuum chamber is kept cooled for 5-30 minutes. Then, the cathode arc power supply and the bias power supply are started again, and after deposition for a period of time, the power supply is turned off again. The deposition and cooling processes are alternately performed until the deposition is finally completed. In this way, the deposition temperature can be effectively controlled to avoid excessively high temperature from adversely affecting the superhard carbon-based coating 33, thereby ensuring the hardness of the superhard carbon-based coating 33.

[0070] There are many implementation methods of the present invention, and all technical solutions formed by equivalent transformation or equivalent transformation fall within the protection scope of the present invention.

Claims

1. A composite surface treatment process for valve components, characterized in that: The steps include: S1, processing the surface of the substrate to obtain a support layer, wherein the thickness of the support layer is between 50 micrometers and 300 micrometers; and the hardness of the support layer is greater than the hardness of the substrate; S2, grinding and polishing the support layer; S3, processing a PVD coating on the polished support layer, wherein the surface layer of the PVD coating is an ultra-hard carbon-based coating, the hardness of the ultra-hard carbon-based coating is greater than the hardness of the support layer, the hardness range of the ultra-hard carbon-based coating is between 3500HV and 6500HV, and the friction coefficient of the ultra-hard carbon-based coating is between 0.06 and 0.1; The S3 comprises the following steps: S31, cleaning the substrate processed by S2; S32, depositing a base layer on the cleaned support layer; S33, depositing a transition layer on the bottom layer; S34, depositing the superhard carbon-based coating on the transition layer; The cleaning comprises the following steps: S311, placing the workpiece on a workpiece holder in the vacuum chamber; S312, evacuate the vacuum chamber to 0.05 Pa; S313, filling the vacuum chamber with argon gas so that the pressure in the vacuum chamber is 0.6-10Pa; S314, turn on the bias power supply and the ion beam source to realize bias glow cleaning and ion beam cleaning to clean the workpiece synchronously; the ion beam source arranged in the vacuum chamber is an anode layer ion source and they are evenly distributed around the workpiece holder; the voltage of the bias power supply when working is between 700-2000V; the voltage of the ion beam source when working is between 300-2000V; the horizontal distance between the inner cathode and the outer cathode of the anode layer ion source is between 4-8mm, and the distance between the cathode and the cathode in the height direction is between 4-8mm; the air pressure in the vacuum chamber is between 0.6-10Pa.

2. The composite surface treatment process for valve components according to claim 1, characterized in that: The support layer is strengthened by thermal spraying or surface heat treatment.

3. The composite surface treatment process for valve components according to claim 1, characterized in that: When the substrate is stainless steel, the support layer is a nickel-based alloy layer, a tungsten carbide layer or a chromium carbide layer obtained by thermal spraying; When the substrate is a titanium alloy, the support layer is a nitriding layer, a carburizing layer, a carbonitriding layer, or an oxygen-permeated layer.

4. The composite surface treatment process for valve components according to claim 1, characterized in that: The hardness of the support layer ranges from 600 HV to 1800 HV.

5. The composite surface treatment process for valve components according to claim 1, characterized in that: The bottom layer and transition layer are deposited by magnetron sputtering process; The superhard carbon-based coating is deposited by using arc ion plating technology.

6. The composite surface treatment process for valve components according to claim 1, characterized in that: The content of diamond phase in the superhard carbon-based coating is not less than 70%.

7. The composite surface treatment process for valve components according to claim 1, characterized in that: The superhard carbon-based coating is a taC coating.

8. The composite surface treatment process for valve components according to any one of claims 1 to 7, characterized in that: The thickness of the superhard carbon-based coating is between 2 microns and 10 microns.

9. A valve component, comprising a base, characterized in that: A support layer is provided on the surface of the substrate, and the hardness of the support layer is greater than the hardness of the substrate; the thickness of the support layer is between 50 microns and 300 microns; a PVD coating is provided on the support layer, and the surface layer of the PVD coating is an ultra-hard carbon-based coating, and the hardness of the ultra-hard carbon-based coating is greater than the hardness of the support layer, the hardness range of the ultra-hard carbon-based coating is between 3500HV and 6500HV, and the friction coefficient of the ultra-hard carbon-based coating is between 0.06 and 0.1; the valve component is processed by the composite surface treatment process for valve components described in any one of claims 1 to 8.

Images