Impact-resistant wear-resistant high-toughness lubricating gradient coating on surface of valve core and preparation method thereof

Abstract

The invention discloses a valve element surface impact-resistant wear-resistant high-toughness lubricating gradient coating and a preparation method thereof, and relates to the technical field of valve element surface treatment.The valve element surface impact-resistant wear-resistant high-toughness lubricating gradient coating comprises a supporting layer, a transition layer and a functional layer which are sequentially stacked on the surface of a valve element base body; the supporting layer is a metal-based composite coating, the transition layer is a component gradient coating composed of metal chromium and chromium carbide, and the functional layer is a diamond-like coating. The mass ratio of metal chromium in the transition layer is gradually reduced in a gradient manner from the side close to the supporting layer to the side close to the functional layer, and the mass ratio of chromium carbide is correspondingly gradually increased in a gradient manner from the side close to the supporting layer to the side close to the functional layer. The valve element has the beneficial effects that the gradient coating composed of the supporting layer, the transition layer and the functional layer is arranged in the local area of the through hole where the valve element makes contact with the motor rotor, the local impact-abrasion-pollution coupling complex working condition is adapted, and the application defect of an existing surface strengthening technology is overcome.

Description

Technical Field

[0001] This invention relates to the field of valve core surface technology, and in particular to an impact-resistant, wear-resistant, high-toughness lubrication gradient coating for valve core surface and its preparation method. Background Technology

[0002] The valve core is the core control component of a proportional directional control valve. It engages with the motor rotor through a locally designed through-hole, achieving precise flow regulation at the valve orifice through back-and-forth sliding. This area where the through-hole contacts the motor rotor must withstand the dynamic pressure impacts, excitation forces, and alternating loads during motor rotor transmission. Furthermore, it experiences high-frequency relative sliding with a micron-level gap between the through-hole and the motor rotor, and directly contacts trace contaminant particles in the hydraulic oil (system assembly residue, component machining residue, or wear debris generated during operation). Under these complex operating conditions, the contact area of ​​the valve core's through-hole is prone to wear, scratches, and fatigue spalling. Even minor surface wear can cause drift in the valve orifice flow characteristics, and scratches can lead to valve core slippage and jamming, severely affecting the control accuracy, response speed, and operational stability of the proportional directional control valve.

[0003] Existing valve core surface strengthening technologies have significant limitations:

[0004] 1. Performance limitations of traditional processes: Carburizing, thermal spraying and other technologies cannot simultaneously meet the multi-dimensional requirements of "high precision, low friction, high toughness and impact resistance" in the valve core contact area (e.g., the high porosity of thermal spray coating cannot meet the high precision performance requirements of local sliding fit; the nitrided layer has limited thickness and insufficient impact resistance).

[0005] 2. Performance contradictions of single coatings: Although diamond-like carbon coatings have low friction and high hardness, they have poor adhesion and are easy to peel off from local areas under impact loads; metal-based coatings (such as cobalt-based alloys and nickel-based coatings) have difficulty in achieving both wear resistance and self-lubrication, and have weak resistance to contaminant wear, making them unsuitable for the complex contact conditions in the valve core through-hole.

[0006] 3. Defects in the synergy of gradient coatings: Existing gradient coatings are mostly "simple stacking of components" and are mostly applied to the entire surface of the valve core. They are not customized for the "impact-wear-contamination" coupled working conditions of the valve core through hole and the motor rotor contact area. The interlayer thermal expansion coefficient and hardness matching are poor, and stress concentration leads to interlayer cracking when resisting impact. They cannot adapt to the complex working environment of the local contact area of ​​the valve core of the proportional control valve. Summary of the Invention

[0007] The main objective of this invention is to propose an impact-resistant, wear-resistant, high-toughness lubricating gradient coating for valve core surfaces and its preparation method, aiming to solve the technical problems of easy cracking and peeling of the coating in the local contact area between the valve core through hole and the motor rotor, insufficient wear resistance and lubrication, which leads to valve core jamming and reduced flow control accuracy.

[0008] To achieve the above objectives, the present invention proposes an impact-resistant, wear-resistant, high-toughness lubricating gradient coating for valve core surfaces, comprising a support layer, a transition layer, and a functional layer sequentially stacked on the surface of a valve core substrate; the support layer is a metal-based composite coating, the transition layer is a compositional gradient coating composed of metallic chromium and chromium carbide, and the functional layer is a diamond-like carbon coating; in the transition layer, the mass percentage of metallic chromium decreases gradually from the side closer to the support layer to the side closer to the functional layer, and the mass percentage of chromium carbide increases gradually from the side closer to the support layer to the side closer to the functional layer.

[0009] In one embodiment, the support layer comprises a cobalt-based alloy, chromium carbide, and oxide additives, wherein the oxide additives are used to optimize the high-temperature stability of the support layer.

[0010] In one embodiment, the valve core substrate is made of martensitic stainless steel or martensitic precipitation hardening steel.

[0011] In one embodiment, the initial mass percentage of metallic chromium in the transition layer is not less than 60%, the final mass percentage is not more than 20%, and the change in the proportion of chromium carbide is inversely matched with the gradient of metallic chromium.

[0012] In one embodiment, the transition layer is prepared by using a chromium metal target and a chromium carbide target as co-sputtering targets. During the deposition process, the sputtering power of the chromium target is gradually reduced while the sputtering power of the chromium carbide target is gradually increased, forming a transition surface with a decreasing gradient of metal composition and an increasing gradient of metal carbide composition.

[0013] In one embodiment, during the fabrication of the transition layer, the vacuum chamber pressure is maintained at 0.1-0.2 Pa; a DC pulse bias mode is activated, the frequency is set to 10-100 kHz, the peak value of the DC pulse bias is adjusted to 50-60 V, and the duty cycle is 30-80%; the magnetron sputtering sources for the chromium metal target and the chromium carbide target are activated, with the power density of the chromium metal target magnetron source being 3-7 W / cm² and the power density of the chromium carbide target magnetron source being 1-2 W / cm². 2 By linearly reducing the power density of the metallic chromium magnetron target, the power of the chromium carbide magnetron target was reduced from 1-2 W / cm². 2 Linearly increase to 3-7 W / cm 2 The operating temperature is 100-200℃.

[0014] Secondly, the present invention provides a method for preparing an impact-resistant, wear-resistant, high-toughness lubrication gradient coating on the surface of a valve core, comprising the following steps:

[0015] S1: The valve core substrate is subjected to sandblasting and ultrasonic cleaning in sequence to remove surface oil and impurities;

[0016] S2: A support layer is prepared on the surface of the valve core substrate using plasma spraying technology with argon-hydrogen mixed gas as the carrier gas;

[0017] S3: Using magnetron sputtering technology, with metallic chromium target and chromium carbide target as co-sputtering targets, by linearly adjusting the sputtering power of the two targets, a transition layer is formed on the surface of the support layer to achieve a gradient distribution of metallic chromium and chromium carbide;

[0018] S4: Using magnetron sputtering technology, a graphite target is used as the sputtering source, and the substrate bias parameters are adjusted to deposit a diamond-like functional layer on the surface of the transition layer.

[0019] In one embodiment, the operating temperature is controlled within the range of 100-200°C during the plasma spraying in step S2 and the magnetron sputtering in steps S3 and S4.

[0020] In one embodiment, in step S2, the argon flow rate is 40-45 L / min, the hydrogen flow rate is 12-18 L / min, and the distance between the spray gun and the valve core substrate is 90-100 mm.

[0021] This invention utilizes a gradient coating consisting of a support layer, a transition layer, and a functional layer in a localized area of ​​the through-hole where the valve core contacts the motor rotor. This coating adapts to the complex "impact-wear-contamination" coupled working conditions in this localized area, overcoming the application defects of existing surface strengthening technologies. The metal-based composite support layer ensures a stable bond between the coating and the valve core substrate, providing excellent impact resistance and structural toughness to withstand dynamic pressure impacts and alternating loads generated by the motor rotor drive. The transition layer employs a gradient design of metallic chromium and chromium carbide, achieving a smooth transition in performance between the support layer and the functional layer. This significantly alleviates stress concentration caused by the mismatch between the interlayer thermal expansion coefficients and hardness, preventing interlayer cracking or peeling under impact loads. The diamond-like carbon functional layer possesses high wear resistance and low friction characteristics, reducing high-frequency relative sliding wear between the through-hole and the motor rotor, improving resistance to contaminant particle wear, reducing localized wear, scratches, and fatigue spalling, preventing valve orifice flow characteristic drift and valve core slippage, thereby improving the control accuracy of the proportional directional control valve and adapting to the operational requirements under complex working conditions. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0023] Figure 1 A schematic diagram of the process for an impact-resistant, wear-resistant, high-toughness lubrication gradient coating on the surface of a valve core provided by the present invention;

[0024] Figure 2 An exploded structural diagram of the valve body through hole and the motor rotor provided by the present invention;

[0025] Figure 3 A schematic diagram of the structure of an impact-resistant, wear-resistant, high-toughness lubrication gradient coating on the surface of a valve core provided by the present invention;

[0026] The reference numerals in the attached figures are as follows: 1. Substrate; 10. Valve core; 101. Through hole; 2. Support layer; 3. Transition layer; 4. Functional layer; 5. Motor rotor.

[0027] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0028] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0029] It should be noted that if directional indicators (such as up, down, left, right, front, back, etc.) are involved in the embodiments of this invention, these directional indicators are only used to explain the relative positional relationships and movement of the components in a specific posture. If the specific posture changes, the directional indicators will also change accordingly. Unless otherwise explicitly specified and limited, the terms "installed," "connected," and "linked" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to the internal communication between two components. For those skilled in the art, the specific meaning of the above terms in this application can be understood according to the specific circumstances.

[0030] Furthermore, if the embodiments of the present invention involve descriptions using terms such as "first," "second," etc., these descriptions are for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Moreover, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element. Furthermore, the use of "and / or" or "and / or" throughout the text includes three parallel options; for example, "A and / or B" includes option A, option B, or options where both A and B are satisfied simultaneously. Furthermore, the technical solutions of the various embodiments can be combined with each other, but only if they are feasible for those skilled in the art. If the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0031] The present invention proposes an impact-resistant, wear-resistant, high-toughness lubricating gradient coating for valve core surface, comprising a support layer 2, a transition layer 3, and a functional layer 4 sequentially stacked on the surface of valve core 10 substrate 1; the support layer 2 is a metal-based composite coating, the transition layer 3 is a composition gradient coating composed of metallic chromium and chromium carbide, and the functional layer 4 is a diamond-like carbon coating; the mass percentage of metallic chromium in the transition layer 3 decreases gradually from the side closer to the support layer 2 to the side closer to the functional layer 4, and the mass percentage of chromium carbide increases gradually from the side closer to the support layer 2 to the side closer to the functional layer 4.

[0032] By setting a gradient coating consisting of a support layer 2, a transition layer 3 and a functional layer 4 in a local area of ​​the through hole 101 where the valve core 10 contacts the motor rotor 5, the complex working condition of "impact-wear-contamination" coupling in this local area is adapted to overcome the application defects of existing surface strengthening technology.

[0033] In one embodiment, the support layer comprises a cobalt-based alloy, chromium carbide, and oxide additives, wherein the oxide additives are used to optimize the high-temperature stability of the support layer.

[0034] In one embodiment, the valve core substrate is made of martensitic stainless steel or martensitic precipitation hardening steel.

[0035] In one embodiment, the initial mass percentage of metallic chromium in the transition layer is not less than 60%, the final mass percentage is not more than 20%, and the change in the proportion of chromium carbide is matched with the reverse gradient of metallic chromium.

[0036] In one embodiment, the transition layer is prepared by using a chromium metal target and a chromium carbide target as co-sputtering targets. During the deposition process, the sputtering power of the chromium target is gradually reduced while the sputtering power of the chromium carbide target is gradually increased, forming a transition surface with a decreasing gradient of metal composition and an increasing gradient of metal carbide composition.

[0037] In one embodiment, during the preparation of the transition layer, the vacuum chamber pressure is maintained at 0.1-0.2 Pa; the DC pulse bias mode is activated, the frequency is set to 10-100 kHz, the peak value of the DC pulse bias is adjusted to 50-60 V, and the duty cycle is 30-80%; the magnetron sputtering sources for the chromium metal target and the chromium carbide target are activated, with the power density of the chromium metal target magnetron source being 3-7 W / cm² and the power density of the chromium carbide target magnetron source being 1-2 W / cm²; after linearly reducing the power density of the chromium metal magnetron target, the power of the chromium carbide magnetron target is linearly increased from 1-2 W / cm² to 3-7 W / cm²; the operating temperature is 100-200 °C.

[0038] Secondly, the present invention provides a method for preparing an impact-resistant, wear-resistant, high-toughness lubrication gradient coating on the surface of a valve core, comprising the following steps:

[0039] S1: The valve core substrate is subjected to sandblasting and ultrasonic cleaning in sequence to remove surface oil and impurities;

[0040] S2: A support layer is prepared on the surface of the valve core substrate using plasma spraying technology with argon-hydrogen mixed gas as the carrier gas;

[0041] S3: Using magnetron sputtering technology, with metallic chromium target and chromium carbide target as co-sputtering targets, by linearly adjusting the sputtering power of the two targets, a transition layer is formed on the surface of the support layer to achieve a gradient distribution of metallic chromium and chromium carbide;

[0042] S4: Using magnetron sputtering technology, a graphite target is used as the sputtering source, and the substrate bias parameters are adjusted to deposit a diamond-like functional layer on the surface of the transition layer.

[0043] In one embodiment, the operating temperature is controlled within the range of 100-200°C during the plasma spraying in step S2 and the magnetron sputtering in steps S3 and S4.

[0044] In one embodiment, in step S2, the argon flow rate is 40-45 L / min, the hydrogen flow rate is 12-18 L / min, and the distance between the spray gun and the valve core substrate is 90-100 mm.

[0045] The following description, using a preferred embodiment, illustrates the content related to the above embodiments:

[0046] An impact-resistant, wear-resistant, high-toughness lubricating gradient coating for valve core surface and its preparation method are disclosed. The gradient coating consists of a support layer, a transition layer, and a functional layer, with the valve core as the substrate. The support layer is composed of cobalt-based alloy / chromium carbide / yttrium oxide; the transition layer is composed of metallic chromium / chromium carbide; and the functional layer is composed of diamond-like carbon.

[0047] The support layer was prepared using plasma spraying technology, the transition layer was prepared using magnetron sputtering technology, and the functional layer was prepared using magnetron sputtering technology.

[0048] The base material is either martensitic stainless steel or martensitic precipitation hardening steel.

[0049] This invention achieves a synergistic improvement in impact resistance, wear resistance, high toughness, and lubrication performance through a gradual transition in material composition and function. The support layer uses a cobalt-based alloy with a coefficient of thermal expansion matching the valve core material, ensuring adhesion to the valve core surface. Chromium carbide enhances wear resistance and impact resistance, while yttrium oxide improves high-temperature stability. The transition layer employs a gradient system of metallic chromium and chromium carbide, serving as a buffer zone between the support layer and the functional layer, effectively alleviating thermal stress concentration. The functional layer uses diamond-like carbon (DLC) to leverage its core capabilities in wear resistance and lubrication.

[0050] Furthermore, the support layer contains 70-80 wt% cobalt-based alloy, 10-15 wt% chromium carbide, and 5-10 wt% yttrium oxide.

[0051] Furthermore, in the transition layer, the proportion of metallic chromium decreases gradually from 60-80 wt% near the support layer to 10-20 wt% near the functional layer, while the mass proportion of chromium carbide increases gradually from 10-20 wt% to 60-80 wt%.

[0052] This invention also provides the above-mentioned impact-resistant, wear-resistant, high-toughness lubrication gradient coating on the valve core surface and its preparation method, including the following process steps:

[0053] S1: Valve core substrate pretreatment: The valve core is manually sandblasted and then ultrasonically cleaned to remove surface oil and impurities;

[0054] S2: Support layer preparation: An Ar / H2 mixed gas was used as the carrier gas, and a support layer was prepared on the surface of the valve core using plasma spraying technology;

[0055] S3: Transition layer preparation: Using a chromium metal target and a chromium carbide target as co-sputtering targets, during the deposition process, by gradually reducing the sputtering power of the chromium target and gradually increasing the sputtering power of the chromium carbide target, a transition surface with decreasing metal composition gradient and increasing metal carbide composition gradient is formed on the surface of the support layer.

[0056] S4: Functional layer fabrication: Using a graphite target as the sputtering source, a diamond-like layer is deposited on the surface of the transition layer by adjusting the sputtering power and substrate bias.

[0057] Furthermore, in step S2, the Ar flow rate is 40-45 L / min; the H2 flow rate is 12-18 L / min; the distance between the spray gun and the metal substrate is 90-100 mm; the plasma spraying power is 50-70 kW; and the powder feeding rate is 30-40 g / min.

[0058] Further, in step S3, the argon flow rate of the magnetron sputtering target is adjusted to maintain the vacuum chamber pressure at 0.1-0.2 Pa; the DC pulse bias mode is activated, the frequency is set to 10-100 kHz, the peak value of the DC pulse bias is adjusted to 50-60 V, and the duty cycle is 30-80%; the chromium metal target and chromium carbide target magnetron sputtering sources are activated, with the power density of the chromium metal target magnetron sputtering source being 3-7 W / cm³. 2 The power density of the chromium carbide target magnetron source is 1-2 W / cm². 2 By linearly reducing the power density of the metallic chromium magnetron target, the power of the chromium carbide magnetron target was reduced from 1-2 W / cm². 2 Linearly increase to 3-7 W / cm 2 The operating temperature is 100-200℃.

[0059] Further, in step S4, the argon flow rate of the magnetron target source is adjusted to maintain the vacuum chamber pressure at 0.5-1.0 Pa; the frequency is set to 10-100 kHz, the peak value of the DC pulse bias is adjusted to 600-700 V, the duty cycle is 30-80%, and the operating temperature is 100-200 °C.

[0060] The present invention has the following beneficial effects:

[0061] This invention provides an impact-resistant, wear-resistant, high-toughness, lubricating gradient coating for valve core surfaces and its preparation method. The coating is deposited in a localized area where the valve core's through-hole contacts the motor rotor. Through a gradient synergistic design of the support layer, transition layer, and functional layer, the cobalt-based alloy of the support layer matches the thermal expansion coefficient of the valve core substrate, ensuring interfacial adhesion. Chromium carbide enhances impact resistance and wear resistance, while yttrium oxide optimizes high-temperature stability. The gradient system of metallic chromium and chromium carbide in the transition layer forms a performance buffer, alleviating interlayer stress concentration. The diamond-like carbon coating of the functional layer leverages its high wear resistance and self-lubricating properties, significantly improving the valve core's performance synergy under dynamic pressure impacts and alternating loads generated by the motor rotor drive, thus adapting to complex operating conditions.

[0062] This invention introduces a gradient transition layer between the support layer and the functional layer. Through a compositional gradient design, the thermal expansion coefficients and hardness of the layers are gradually matched, improving the interfacial bonding strength and avoiding the risk of interfacial cracking under impact loads or alternating stresses, as is common in traditional coatings. The gradient thermal expansion coefficient design also ensures better thermal matching between the coating and the valve core substrate, eliminating problems such as coating peeling or microcrack propagation caused by stress concentration.

[0063] The gradient coating of this invention is designed with multiple performance characteristics in synergy for complex working conditions of valve core, effectively solving problems such as flow characteristic drift and jamming caused by valve core wear, and significantly improving the control accuracy, response speed and working stability of proportional directional control valve.

[0064] The coating adhesion of the present invention was tested according to the scratch test method of JB / T 8554-1997 adhesion between vapor-deposited thin films and substrates, and the wear performance of the coating was tested by ball-disc friction and wear test.

[0065] The following describes the content related to the above embodiments in conjunction with several preferred embodiments:

[0066] Existing technology:

[0067] In the prior art, the substrate is a martensitic precipitation hardening steel valve core. A diamond-like carbon coating is deposited on the surface of the substrate using magnetron sputtering technology, so that a certain bonding force is formed between the diamond-like carbon coating and the substrate. This forms a protective coating with high hardness and low friction coefficient on the surface of the valve core, thereby improving the wear and loss of the contact part between the valve core through hole and the motor rotor.

[0068] Example 1:

[0069] In this embodiment, the substrate is a martensitic precipitation-hardening steel valve core. The support layer contains 80 wt% cobalt-based alloy, 12 wt% chromium carbide, and 8 wt% yttrium oxide. In the transition layer, the proportion of metallic chromium decreases from 60 wt% near the support layer to 20 wt% near the functional layer, while the mass proportion of chromium carbide increases from 20 wt% to 60 wt%.

[0070] The preparation method includes the following process steps:

[0071] S1: Valve core substrate pretreatment: The valve core is manually sandblasted and then ultrasonically cleaned to remove surface oil and impurities;

[0072] S2: Support layer preparation: An Ar / H2 mixed gas was used as the carrier gas, and a support layer was prepared on the surface of the valve core using plasma spraying technology;

[0073] Ar flow rate is 40 L / min; H2 flow rate is 16 L / min; distance between spray gun and metal substrate is 100 mm; plasma spraying power is 60 kW; powder feeding rate is 40 g / min.

[0074] S3: Transition layer preparation: Using a chromium metal target and a chromium carbide target as co-sputtering targets, during the deposition process, by gradually reducing the sputtering power of the chromium target and gradually increasing the sputtering power of the chromium carbide target, a transition surface with decreasing metal composition gradient and increasing metal carbide composition gradient is formed on the surface of the support layer.

[0075] Adjust the argon flow rate of the magnetron sputtering source to maintain the vacuum chamber pressure at 0.1 Pa; activate the DC pulse bias mode, set the frequency to 100 kHz, adjust the DC pulse bias peak value to 50 V, and the duty cycle to 40%; activate the chromium metal target and chromium carbide target magnetron sputtering sources, with the chromium metal target magnetron source power density at 6 W / cm³. 2 The power density of the chromium carbide target magnetron source is 1 W / cm². 2 By linearly reducing the power density of the metallic chromium magnetron target, the power of the chromium carbide magnetron target decreased from 1 W / cm². 2 Linearly increase to 6 W / cm 2 The operating temperature is 100℃.

[0076] S4: Functional layer fabrication: Using a graphite target as the sputtering source, a diamond-like layer is deposited on the surface of the transition layer by adjusting the sputtering power and substrate bias.

[0077] Adjust the argon flow rate of the magnetron target source to maintain the vacuum chamber pressure at 1.0 Pa; set the frequency to 100 kHz, adjust the DC pulse bias peak value to 600 V, and the duty cycle to 40%; and set the operating temperature to 100 °C.

[0078] Example 2:

[0079] In this embodiment, the substrate is a martensitic precipitation-hardening steel valve core. The support layer contains 75 wt% cobalt-based alloy, 15 wt% chromium carbide, and 10 wt% yttrium oxide. In the transition layer, the proportion of metallic chromium decreases from 70 wt% near the support layer to 10 wt% near the functional layer, while the mass proportion of chromium carbide increases from 10 wt% to 70 wt%.

[0080] The preparation method includes the following process steps:

[0081] S1: Valve core substrate pretreatment: The valve core is manually sandblasted and then ultrasonically cleaned to remove surface oil and impurities;

[0082] S2: Support layer preparation: An Ar / H2 mixed gas was used as the carrier gas, and a support layer was prepared on the surface of the valve core using plasma spraying technology;

[0083] Ar flow rate is 40 L / min; H2 flow rate is 12 L / min; distance between spray gun and metal substrate is 100 mm; plasma spraying power is 50 kW; powder feeding rate is 50 g / min.

[0084] S3: Transition layer preparation: Using a chromium metal target and a chromium carbide target as co-sputtering targets, during the deposition process, by gradually reducing the sputtering power of the chromium target and gradually increasing the sputtering power of the chromium carbide target, a transition surface with decreasing metal composition gradient and increasing metal carbide composition gradient is formed on the surface of the support layer.

[0085] Adjust the argon flow rate of the magnetron sputtering source to maintain the vacuum chamber pressure at 0.1 Pa; enable the DC pulse bias mode, set the frequency to 100 kHz, adjust the DC pulse bias peak value to 60 V, and the duty cycle to 40%; enable the magnetron sputtering sources for the chromium metal target and the chromium carbide target, with the chromium metal target magnetron source power density at 5 W / cm³. 2 The power density of the chromium carbide target magnetron source is 2 W / cm². 2 By linearly reducing the power density of the metallic chromium magnetron target, the power of the chromium carbide magnetron target decreased from 2 W / cm². 2 Linearly increase to 5 W / cm 2 The operating temperature is 100℃.

[0086] S4: Functional layer fabrication: Using a graphite target as the sputtering source, a diamond-like layer is deposited on the surface of the transition layer by adjusting the sputtering power and substrate bias.

[0087] Adjust the argon flow rate of the magnetron target source to maintain the vacuum chamber pressure at 0.5 Pa; set the frequency to 100 kHz, adjust the DC pulse bias peak value to 600 V, and the duty cycle to 40%; and set the operating temperature to 100 °C.

[0088] Example 3:

[0089] In this embodiment, the substrate is a martensitic precipitation-hardening steel valve core. The support layer contains 80 wt% cobalt-based alloy, 15 wt% chromium carbide, and 5 wt% yttrium oxide. In the transition layer, the proportion of metallic chromium decreases from 60 wt% near the support layer to 20 wt% near the functional layer, while the mass proportion of chromium carbide increases from 20 wt% to 60 wt%.

[0090] The preparation method includes the following process steps:

[0091] S1: Valve core substrate pretreatment: The valve core is manually sandblasted and then ultrasonically cleaned to remove surface oil and impurities;

[0092] S2: Support layer preparation: An Ar / H2 mixed gas was used as the carrier gas, and a support layer was prepared on the surface of the valve core using plasma spraying technology;

[0093] Ar flow rate is 42 L / min; H2 flow rate is 18 L / min; distance between spray gun and metal substrate is 90 mm; plasma spraying power is 50 kW; powder feeding rate is 40 g / min.

[0094] S3: Transition layer preparation: Using a chromium metal target and a chromium carbide target as co-sputtering targets, during the deposition process, by gradually reducing the sputtering power of the chromium target and gradually increasing the sputtering power of the chromium carbide target, a transition surface with decreasing metal composition gradient and increasing metal carbide composition gradient is formed on the surface of the support layer.

[0095] Adjust the argon flow rate of the magnetron sputtering source to maintain the vacuum chamber pressure at 0.1 Pa; activate the DC pulse bias mode, set the frequency to 90 kHz, adjust the DC pulse bias peak value to 50 V, and the duty cycle to 30%; activate the chromium metal target and chromium carbide target magnetron sputtering sources, with the chromium metal target magnetron source power density at 6 W / cm³. 2 The power density of the chromium carbide target magnetron source is 2 W / cm². 2 By linearly reducing the power density of the metallic chromium magnetron target, the power of the chromium carbide magnetron target decreased from 2 W / cm². 2 Linearly increase to 6 W / cm 2 The operating temperature is 200℃.

[0096] S4: Functional layer fabrication: Using a graphite target as the sputtering source, a diamond-like layer is deposited on the surface of the transition layer by adjusting the sputtering power and substrate bias.

[0097] Adjust the argon flow rate of the magnetron target source to maintain the vacuum chamber pressure at 1.0 Pa; set the frequency to 100 kHz, adjust the DC pulse bias peak value to 600 V, and the duty cycle to 30%; and set the operating temperature to 200 °C.

[0098] Table 1 shows the test results of the compatibility between the embodiments and the prior art.

[0099] Test Results Example 1 Example 2 Example 3 Existing technology Bonding force (N) 50±2 42±2 53±2 18±2

[0100] In summary, compared with the single-layer diamond-like carbon coatings in the prior art, all three sets of embodiments exhibited excellent bonding strength. Among them, the bonding strength test results of Embodiment 3 were the best, verifying that the gradient coating, through the synergistic design of "support layer-transition layer-functional layer", effectively alleviates the problem of interfacial stress mismatch between the coating and the substrate, improves the bonding strength between the coating and the substrate, and further ensures that the coating can still maintain good adhesion performance under the complex working conditions of the proportional directional control valve core, and is not prone to peeling failure.

[0101] Table 2 shows the friction and wear rate test results of the examples.

[0102]

[0103] In summary, all three sets of coatings exhibited excellent wear resistance. Among them, Example 3 performed best in terms of adhesion and wear rate, while Example 2 showed relatively balanced performance across all indicators. All test results verified that the gradient coating, through the synergistic design of "support layer-transition layer-functional layer", effectively solved the problem that traditional coatings are difficult to balance in terms of impact resistance, wear resistance, and lubrication performance, and can meet the high reliability requirements of proportional directional control valve cores under complex operating conditions.

[0104] Table 3 shows the specific parameters of the transition layer coating in Example 1.

[0105]

[0106]

[0107] In the deposition process of Example 1, by adjusting the sputtering power of the chromium target and the chromium carbide target, the mass percentage of metallic chromium on the side of the transition layer near the support layer is 60 wt%, and it gradually decreases to 20 wt% along the coating thickness direction towards the functional layer; correspondingly, the mass percentage of chromium carbide increases synchronously from 20 wt% to 60 wt%, and finally a transition layer with a thickness of 1.7 μm is deposited. This gradient composition design can effectively build a performance buffer and effectively form a performance buffer between layers, thus alleviating stress concentration between layers.

[0108] It should be understood that the terms "one embodiment" or "one example" throughout the specification mean that a specific feature, structure, or characteristic related to the embodiment is included in at least one embodiment of the invention. Therefore, "in one embodiment" or "in one example" appearing throughout the specification do not necessarily refer to the same embodiment. Furthermore, these specific features, structures, or characteristics can be combined in any suitable manner in one or more embodiments. Those skilled in the art should also recognize that the embodiments described in the specification are optional embodiments, and the actions and modules involved are not necessarily essential to the invention.

[0109] In various embodiments of the present invention, it should be understood that the sequence number of each process does not necessarily imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0110] The flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various embodiments of this application. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of code containing one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions indicated in the blocks may occur in a different order than those indicated in the drawings. For example, two consecutively indicated blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. It is particularly important to note that each block in the block diagrams and / or flowcharts, and combinations of blocks in the block diagrams and / or flowcharts, can be implemented using a dedicated hardware-based system that performs the specified function or operation, or using a combination of dedicated hardware and computer instructions.

[0111] The above description is merely an exemplary embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention's specification and drawings under the technical concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A valve trim surface impact resistant wear resistant high toughness lubricious gradient coating characterized by: The valve core base body comprises a support layer, a transition layer and a functional layer which are sequentially stacked on the surface of the valve core base body; the support layer is a metal-based composite coating, the transition layer is a composition gradient coating composed of metallic chromium and chromium carbide, and the functional layer is a diamond-like carbon coating; the mass percentage of metallic chromium in the transition layer decreases from the side close to the support layer to the side close to the functional layer, and the mass percentage of chromium carbide increases from the side close to the support layer to the side close to the functional layer.

2. A valve trim surface impact and wear resistant high toughness lubricious gradient coating as defined in claim 1 wherein: The support layer comprises a cobalt-based alloy, chromium carbide and an oxide additive for optimizing the high-temperature stability of the support layer.

3. A valve trim surface impact and wear resistant high toughness lubricious gradient coating according to claim 1 wherein: The material of the valve core base body is martensitic stainless steel or martensitic precipitation hardening steel.

4. A valve trim surface impact and wear resistant high toughness lubricious gradient coating as defined in claim 1 wherein: The initial mass percentage of metallic chromium in the transition layer is not less than 60%, and the terminal mass percentage is not higher than 20%, and the percentage change of chromium carbide is inversely gradient matched with that of metallic chromium.

5. A valve trim surface impact and wear resistant high toughness lubricious gradient coating according to claim 1 wherein: The transition layer is prepared by using a metallic chromium target and a chromium carbide target as co-sputtering target materials, gradually reducing the sputtering power of the chromium target and gradually increasing the sputtering power of the chromium carbide target during deposition, thereby forming a transition surface with a gradient-decreasing metallic composition and a gradient-increasing metallic carbide composition.

6. A valve trim surface impact and wear resistant, high toughness, lubricious gradient coating according to claim 4, characterized by: The transition layer is prepared when the pressure in the vacuum chamber is kept at 0.1-0.2 Pa; the direct current pulse bias mode is started, the frequency is set to 10-100 kHz, the peak value of the direct current pulse bias is adjusted to 50-60 V, and the duty cycle is 30-80%; the metal chromium target and the chromium carbide target magnetron sputtering sources are started, the power density of the metal chromium target magnetron source is 3-7 W / cm 2 , and the power density of the chromium carbide target magnetron source is 1-2 W / cm 2 ; the power density of the metal chromium magnetron target is linearly reduced, and the power of the chromium carbide magnetron target is linearly increased from 1-2 W / cm 2 to 3-7 W / cm 2 ; and the operating temperature is 100-200℃.

7. A method of making a valve trim surface impact resistant wear resistant high toughness lubricious gradient coating, characterized by, The method comprises the following steps: S1: sandblasting and ultrasonic cleaning are sequentially performed on the valve core base body to remove surface oil stains and impurities; S2: a support layer is prepared on the surface of the valve core base body by using plasma spraying technology with argon-hydrogen mixed gas as the carrier gas; S3: a transition layer is formed on the surface of the support layer by using magnetron sputtering technology with a metallic chromium target and a chromium carbide target as co-sputtering target materials, and the sputtering power of the two target materials is linearly adjusted to realize the gradient distribution of metallic chromium and chromium carbide; S4: a diamond-like carbon functional layer is deposited on the surface of the transition layer by using magnetron sputtering technology with a graphite target as the sputtering source and adjusting the substrate bias parameters.

8. A method of making a valve trim surface impact and wear resistant high toughness lubricious gradient coating as recited in claim 7 wherein, In the plasma spraying of step S2 and the magnetron sputtering processes of steps S3 and S4, the operation temperature is controlled in the range of 100-200℃.

9. A method of making a valve trim surface impact and wear resistant high toughness lubricious gradient coating as defined in claim 7 wherein: In step S2, the argon gas flow rate is 40-45L / min, the hydrogen gas flow rate is 12-18L / min, and the distance between the spray gun and the valve core base body is 90-100mm.

Images