Metal surface high wear resistance and corrosion resistance composite strengthening layer and preparation method thereof

Abstract

The present application relates to a kind of metal surface high wear-resistant corrosion-resistant composite strengthening layer and preparation method thereof, the composite strengthening layer is composed of bearing layer, transition layer, functional layer, bearing layer is nitriding layer, transition layer is oxygen permeation layer, functional layer is nanocomposite ceramic layer, bearing layer preparation method is ion nitriding, thickness is 20 μm~300 μm;Transition layer thickness is 1 μm~3 μm, is prepared by three-stage ion oxygen permeation;Functional layer preparation method is the composite layer of vacuum ion deposition chromium nitride layer and multinary nitride layer.The composite strengthening layer of the present application is small, and the organization structure is dense, and the combination strength is high, and the surface hardness is high, and the friction coefficient is small, the composite strengthening layer combines the performance advantage of single strengthening layer, that is, it has better wear resistance, and it also has better corrosion resistance, especially improves the wear resistance and corrosion resistance of part in service condition, especially suitable for the sealing surface strengthening of chemical ball valve.

Description

Technical Field

[0001] This invention belongs to the field of metal surface hardening treatment technology, and relates to a high wear-resistant and corrosion-resistant composite reinforcing layer and its preparation method. It is particularly suitable for use in high wear and strong corrosion conditions, and can be used to strengthen the sealing surface of ball valves, as well as for surface strengthening of other steel materials. Background Technology

[0002] With the development of industrial technology, the application fields of ball valves are constantly expanding. They are mainly used in harsh and demanding working conditions such as petrochemical, coal chemical, and polysilicon production. The sealing surfaces of their important components (the contact surfaces between the ball and the valve seat) are constantly exposed to corrosion from strong acids, alkalis, and highly abrasive media, placing increasingly higher demands on their overall performance. For example, high-hardness coal slag particles or SO42- present during the operation of ball valves... -2 Cl - In highly corrosive ionic media, the sealing surface of ball valves often exhibits corrosion and wear, leading to premature failure of the reinforced layer. Furthermore, due to the prolonged exposure to high-speed, temperature-cyclical media during ball valve service, the coating is prone to peeling and flaking, directly impacting the valve's lifespan. In summary, the reinforced layer of a ball valve must possess excellent combined corrosion and wear resistance mechanical properties. However, currently used coatings offer relatively limited performance and are insufficient to meet the high-quality, high-parameter performance requirements of components. Currently, several companies both domestically and internationally have invested significant resources in researching this topic.

[0003] US Patent US2018 / 0274076 A1 discloses a high-pressure, high-temperature, dense, low-friction coating method that combines a supersonic spray coating with a DLC coating. This composite coating is unsuitable for media with alternating temperature cycles, and the difference in expansion coefficients between the supersonic coating and the substrate results in poor adhesion and impact toughness. Chinese Patent 201610231094.2 mentions a surface hardening treatment method for ball valve sealing pairs. While the composite reinforced layer prepared by this method has certain corrosion and wear resistance, the large hardness gradient between the coating and the substrate makes it prone to peeling off due to internal stress, limiting its application. Chinese Patents 202010036201.2 and 201610248224.3 mention a ball valve wear-resistant and corrosion-resistant protective coating and its preparation method. The coatings prepared by these two methods are not suitable for Cl... -The ion-corrosion environment is complex and the preparation process is difficult to promote and apply. Chinese patent CN201310255912.9 mentions a PVD composite ceramic coating screw and its manufacturing method. The screw substrate (1) has a nitriding layer (2) with a thickness greater than 0.2 mm on its surface. The outer surface of the nitriding layer (2) is provided with a transition layer (3) and a wear-resistant layer (4) stacked from the inside to the outside. Specifically, the screw substrate made of chromium-molybdenum alloy steel is subjected to ion nitriding treatment in an argon atmosphere at 400℃, and the thickness of the nitriding layer is ensured to be greater than 0.2 mm. The outer surface of the nitriding layer is provided with a transition layer and a wear-resistant layer stacked from the inside to the outside. The transition layer is a 0.5 μm-1 μm thick metallic chromium layer, and the wear-resistant layer is a 5 μm-7 μm thick composite ceramic coating composed of chromium nitride and carbon nitride. To improve the adhesion between the steel substrate and the nitride ceramic layer, ion nitriding is a common practice in this field. For example, in the study "Research on Improving the Adhesion Between Hard Film Layer and Ordinary Structural Steel Substrate through Ion Nitriding," TiN plating was performed after ion nitriding pretreatment, resulting in nearly double the adhesion between the coating and the substrate compared to direct plating. However, further research revealed some shortcomings in the current nitrided layer, such as a loose structure and a hard, brittle, bright white layer on its surface. These issues severely affect the deposition of the nitride ceramic layer on its surface, making it difficult to further improve the adhesion strength between the nitride ceramic layer and the outer nitride ceramic layer, leading to coating wear and peeling. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a high-wear-resistant and corrosion-resistant composite reinforcement layer for metal surfaces and its preparation method. The composite reinforcement layer prepared by this invention has a gentle hardness gradient, low internal stress, and high bonding strength with the substrate, thus possessing both high wear resistance and corrosion resistance.

[0005] To solve the above-mentioned technical problems, the technical solution provided by the present invention is as follows:

[0006] A high wear-resistant and corrosion-resistant composite reinforcement layer for metal surfaces is composed of a support layer, a transition layer, and a functional layer. The support layer is an ion-nitrided layer, the transition layer is a dense oxygen-diffused layer, and the functional layer is a nano-composite ceramic layer.

[0007] Furthermore, the supporting layer is an ion-nitrided layer without a porous structure, with a hardness of 1000HV to 1300HV and a thickness of 20μm to 300μm; the transition layer is a dense ion-nitrided layer with a thickness of 1μm to 3μm; the functional layer is a composite layer of chromium nitride and multi-component nitride, with a hardness of 3000HV to 4000HV and a thickness of 1μm to 10μm; the total depth of the composite reinforcement layer is 22μm to 310μm, and the final surface roughness Ra ≤ 0.2μm.

[0008] The present invention also provides a method for preparing the above-mentioned high wear-resistant and corrosion-resistant composite reinforcement layer. The specific steps of the preparation method are as follows: First, the surface of the steel substrate is ground, polished, and ion cleaned. Then, the following steps are performed in sequence: ① ion sputtering, ② low-temperature and low-pressure ion nitriding, ③ three-stage ion oxygenation, and ④ vacuum ion deposition of a composite layer of chromium nitride layer and multi-component nitride layer.

[0009] The specific steps are as follows:

[0010] (1) First, the steel substrate surface is ground, polished, and ion cleaned. Then, the sample is placed in an ion nitriding furnace, and after the vacuum is drawn to a certain degree, hydrogen gas is introduced for ion sputtering. Then, nitriding medium is introduced for ion nitriding.

[0011] (2) After nitriding, an oxidizing medium is introduced to carry out a three-stage ion oxygenation process.

[0012] (3) Finally, the sample is placed in a vacuum coating machine, a deposition atmosphere is introduced, and a composite layer of chromium nitride and multi-component nitride is deposited using non-equilibrium magnetron sputtering technology.

[0013] Step (1) The ion sputtering gas medium is hydrogen; ion sputtering is carried out in an ion nitriding furnace, the vacuum is evacuated to below 20 Pa, the voltage and current are adjusted to start the ignition, and then hydrogen is introduced for ion sputtering, the sputtering time is 5 min to 30 min.

[0014] The ion nitriding gas is a mixture of nitrogen and hydrogen or a single ammonia gas; more preferably, the medium used for ion nitriding is a nitrogen to hydrogen volume ratio of 3:1; the ion nitriding temperature is 250℃~500℃, the holding time is 1h~9h, and the atmosphere pressure inside the nitriding furnace is low pressure 20Pa~150Pa. The hardness of the ion nitrided layer is 1000HV~1300HV, and the thickness is 20μm~300μm.

[0015] Step (2) The ion permeation medium is dry and clean air, the ion permeation temperature is 250℃~400℃, the holding time is 15min, the three-stage ion permeation process refers to the permeation flow rates of 2L / min-3L / min, holding for 5min; 4L / min-5L / min, holding for 5min; 5L / min-6L / min, holding for 5min, the furnace atmosphere pressure is 50Pa~150Pa; the dense ion permeation layer has a thickness of 1μm~3μm.

[0016] Step (3) The composite layer of deposited chromium nitride and multi-component nitride layers uses a combination of nitrogen and argon as the gas medium. After ion percolation, the sample is placed in an ion vacuum coating furnace. The coating targets are Si, Cr, and CrAl. Argon gas is first introduced for ion sputtering. The argon flow rate is set to 400 mL / min-600 mL / min, and the argon sputtering time is set to 5 min-30 min. After sputtering, nitrogen gas is introduced and the nitrogen flow rate is adjusted to 500 mL / min-900 mL / min. The coating temperature is set to 400℃-550℃, the bias voltage to 50V-150V, the vacuum degree to 10-3 Pa-10-4 Pa, and the holding time to 4 h-8 h. After vacuum coating, the nitrogen and argon gas valves are closed. After the furnace temperature drops below 100℃, the sample is taken out and its surface is polished to ensure that the final surface roughness Ra≤0.2μm. The functional layer has a hardness of 3000HV to 4000HV and a thickness of 1μm to 10μm.

[0017] Step (3) Chromium nitride is CrN; multi-component nitrides refer to SiAlCrN, etc., which are composed of elements such as Si, Cr, and Al.

[0018] According to the above scheme: the total depth of the composite reinforcement layer is 22μm~310μm, and the surface of the sample is polished to ensure that the final surface roughness Ra≤0.2μm.

[0019] This invention improves upon existing reinforcing layer structures by proposing a composite reinforcing layer consisting of a support layer, a transition layer, and a functional layer. The outer functional layer is a high-hardness, low-friction coefficient nanostructured hard chromium nitride layer and a multi-component nitride layer obtained by vacuum ion deposition, with a hardness of 3000 HV to 4000 HV.

[0020] To improve the bonding strength between the surface functional layer and the steel substrate, the hardness gradient of the composite reinforcement layer is optimized through preparation conditions to reduce internal stress in the coating and avoid the eggshell effect. The load-bearing layer is an ion-nitrided layer that chemically bonds with the substrate. This nitrided layer has a hardness of approximately 1000 HV to 1300 HV, resulting in a relatively small hardness gradient from the surface to the substrate. However, after nitrogen atoms penetrate the stainless steel substrate, they react chemically with chromium atoms, leading to chromium depletion and reduced corrosion resistance. Furthermore, the nitrided layer reduces the bonding force between the ceramic coating and the nitrided layer, thus lowering the overall bonding strength of the composite reinforcement layer. To address these shortcomings of existing technologies, this invention employs a three-stage ion oxygen infiltration process. Dry air is used as the oxidation medium, with the flow rate set in three stages from low to high, generating a dense oxygen-infiltrated layer as an intermediate transition layer. First, the three-stage oxygen permeation method ensures low residual stress within the oxide layer, allowing it to firmly grow on the nitride layer. By controlling the oxidation process, a magnetite phase (Fe3O4) is obtained as the main phase, resulting in superior corrosion resistance of the nitride layer and significantly improving its corrosion resistance. Second, during the growth of the ion-permeated membrane, nanoscale oxide particles gradually occupy the interstitial spaces in the loose layer, effectively increasing the bonding strength between the nanostructured composite ceramic layer and the nitride layer. This makes the composite reinforcement layer more firmly bonded to the substrate, preventing peeling. Furthermore, the nanostructured composite ceramic layer is designed as a composite structure of a chromium nitride layer and a multi-component nitride coating, facilitating the growth of the two layers into a single unit, further reducing internal stress between the layers and increasing the bonding force between the nanostructured layers. In summary, by optimizing the composite reinforcement layer structure, a highly wear-resistant and corrosion-resistant composite reinforcement layer with dense structure, good bonding strength, high surface hardness, and low coefficient of friction is obtained.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0022] (1) The bearing layer and functional layer of the composite reinforcement layer of the present invention are respectively composed of a nitride layer and a nanostructured composite ceramic layer. The nitride layer is chemically bonded to the substrate, and the nanostructured composite ceramic layer is a composite layer of chromium nitride layer and multi-component nitride coating, which has a dense structure and high wear resistance. The bearing layer and functional layer complement each other and work synergistically to form a composite reinforcement layer with comprehensive performance characteristics of low friction coefficient, high surface hardness and gentle hardness gradient, and low internal stress.

[0023] (2) The present invention adds an intermediate transition layer to effectively avoid the performance defects of poor bonding strength and low corrosion resistance of the nitrided layer. That is, by designing a three-stage ion oxygen infiltration process, a unique structure of oxygen infiltration layer is obtained, which improves the microstructure of the nitrided layer and enhances the bonding force between the nitrided layer and the ceramic layer; on the other hand, it improves the poor corrosion resistance of the stainless steel nitrided layer. The transition layer makes the nitrided layer and the ceramic layer firmly bonded to the substrate, effectively ensuring the service life of the composite reinforcement layer under harsh working conditions. Attached Figure Description

[0024] The invention will be further described below with reference to the accompanying drawings.

[0025] Figure 1 The cross-sectional microstructure of the composite reinforcement layer in Example 1 is shown.

[0026] Figure 2 Electrochemical curves of the reinforcement layer for comparative and example cases.

[0027] Figure 3 The friction coefficient curves of the reinforced layer are shown for comparison and examples.

[0028] Figure 4 The images show the wear morphology of the reinforced layer in the comparative examples and embodiments. Detailed Implementation

[0029] The present invention will now be further described with reference to specific embodiments. The following embodiments are intended to illustrate the present invention and not to further limit the present invention.

[0030] Comparative Example 1

[0031] 316 stainless steel was selected as the experimental substrate material. Its surface was ground, polished, ion-cleaned, and dried. Then, it was placed in an ion nitriding furnace. When the vacuum was reduced to <20 Pa, the voltage and current were adjusted to initiate ignition. Hydrogen gas was then introduced for ion sputtering for 5 minutes. Nitrogen gas was then introduced, with the nitrogen-to-hydrogen volume ratio adjusted to 3:1. Nitriding was started when the temperature reached the nitriding temperature of 400℃. The nitriding atmosphere pressure was set to 100 Pa, and the holding time was 6 hours. After ion nitriding, the nitrogen and hydrogen valves were closed. Once the furnace temperature dropped below 100℃, the sample was removed from the furnace, and its surface was polished to ensure a final surface roughness Ra ≤ 0.2 μm.

[0032] The thickness and hardness of the composite reinforcing layer were analyzed according to standards JB / T 7707 and ISO14477-1, respectively. Table 1 shows that the ion-nitrided layer thickness is 50 μm, and the surface hardness is 1080 HV, 1050 HV, and 1030 HV (measured three times, averaged). This indicates that there is no peeling between the reinforcing layer and the substrate, mainly due to the intermolecular chemical bonding between the nitrided layer and the substrate. Friction and wear tests were conducted on the reinforcing layer according to standard ASTM G133, using a reciprocating friction method. The test temperature was room temperature, the load was set at 80 N, the reciprocating length at 5 mm, the running speed at 800 t / min, and the wear time at 10 min. Table 1 shows that the frictional weight loss is 57*10. -3 mm 3 The friction coefficient was 0.70; an electrochemical corrosion experiment was conducted on the reinforced layer using a 3.5% NaCl salt solution. Figure 2The self-corrosion potential is approximately -550mV. Observation of the surface morphology after corrosion revealed no peeling or flaking. In summary, the nitrided layer exhibits good bonding strength with the substrate and excellent wear resistance, but its corrosion resistance is poor.

[0033] Comparative Example 2

[0034] 316 stainless steel was selected as the experimental substrate material. Its surface was ground, polished, subjected to ultrasonic ion cleaning, and dried. Then, it was placed in an ion vacuum coating furnace. The coating targets were Si, Cr, and CrAl targets. A vacuum of 10⁻⁶ was applied. -3 Pa, adjust voltage and current to ignite, then introduce argon gas for ion sputtering, setting the argon gas flow rate to 500 mL / min. After sputtering for 10 min, continue introducing nitrogen gas, adjusting the nitrogen gas flow rate to 800 mL / min, setting the bias voltage to 70 V, and setting the vacuum degree to 10. -4 The coating temperature was 500℃, and the holding time was 6h. After vacuum coating, a CrN-CrAlSiN nanocomposite coating was obtained. The nitrogen and argon valves were closed, and the furnace temperature was lowered to below 100℃. The sample was then taken out of the furnace and its surface was polished to ensure that the final surface roughness Ra≤0.2μm.

[0035] The bonding strength, thickness, and hardness of the composite reinforcing layer were analyzed according to standards JB / T 8554, JB / T 7707, and ISO14477-1, respectively. Table 1 shows that the composite layer of chromium nitride and multi-component nitride has a thickness of 3 μm, surface hardness of 3780 HV, 3750 HV, and 3800 HV, and a bonding strength of only 50 N. This is mainly due to the low hardness of the substrate and the high hardness of the surface ceramic, resulting in a large difference in hardness between the reinforcing layer and the substrate, high internal stress in the reinforcing layer, and a tendency to produce an eggshell effect, leading to poor bonding strength with the substrate. Friction and wear tests were conducted on the reinforcing layer according to standard ASTM G133, using a reciprocating friction method. The test temperature was room temperature, the load was set at 80 N, the reciprocating length at 5 mm, the running speed at 800 t / min, and the wear time at 10 min. Table 1 shows that the frictional weight loss was 50*10. -3 mm 3 The coefficient of friction is 0.65. Although the surface reinforcement layer has high hardness, its wear resistance is generally poor. This is mainly because the reinforcement layer is not firmly bonded to the substrate, and the wear resistance is not significantly improved. Electrochemical corrosion experiments were conducted on the reinforcement layer using a 3.5% NaCl salt solution. Figure 2 The self-corrosion potential is approximately -480mV. Observation of the surface morphology after corrosion revealed no peeling or flaking, indicating superior corrosion resistance compared to the nitride layer. In summary, this nitride coating exhibits high hardness, moderate wear resistance, and poor adhesion to the substrate.

[0036] Comparative Example 3

[0037] 316 stainless steel was selected as the experimental substrate material. Its surface was ground, polished, subjected to ion ultrasonic cleaning, and dried. Then, it was placed in an ion nitriding furnace. When the vacuum was reduced to <20 Pa, the voltage and current were adjusted to initiate ignition. Hydrogen gas was then introduced for ion sputtering. After sputtering for 5 minutes, nitrogen gas was introduced, with a nitrogen-to-hydrogen ratio of 3:1. Nitriding was initiated when the temperature reached the nitriding temperature of 400℃, with a nitriding atmosphere pressure of 100 Pa and a holding time of 6 hours. After ion nitriding, it was placed in an ion vacuum coating furnace. The coating targets were Si, Cr, and CrAl targets. The voltage and current were adjusted to initiate ignition. Argon gas was then introduced for ion sputtering at a flow rate of 500 mL / min. After sputtering for 10 minutes, nitrogen gas was introduced again, with a flow rate of 800 mL / min. The coating temperature was set to 500℃, the bias voltage to 70 V, and the vacuum level to 10. -4 Pa, heat treatment time is 6h. After vacuum coating is completed, the nitrogen and argon valves are closed. After the furnace temperature drops below 100℃, the sample is taken out and its surface is polished to ensure that the final surface roughness Ra≤0.2μm.

[0038] The bonding strength, thickness, and hardness of the composite reinforcing layer were analyzed according to standards JB / T 8554, JB / T 7707, and ISO14477-1, respectively. As shown in Table 1, the thickness of the reinforcing layer is 50 μm, the surface hardness is 3790 HV, 3810 HV, and 3805 HV, and the bonding strength is about 53 N. The bonding strength is not high. This is mainly because there are defects in the porous layer and the white bright layer on the surface of the nitride layer. The white bright layer was not reduced by the oxygen infiltration process, which reduced the bonding strength between the nitride ceramic coating and the nitride layer, resulting in a low bonding strength between the two.

[0039] Comparative Example 4

[0040] 316 stainless steel was selected as the experimental substrate material. Its surface was ground, polished, ultrasonically cleaned with ions, and dried. Then, it was placed in an ion nitriding furnace. When the vacuum was reduced to <20 Pa, the voltage and current were adjusted to initiate ignition. Hydrogen gas was then introduced for ion sputtering. After 5 minutes of sputtering, nitrogen gas was introduced, with a nitrogen-to-hydrogen ratio of 3:1. Ion nitriding was started when the temperature reached the nitriding temperature of 400℃. The nitriding atmosphere pressure was set to 100 Pa, and the holding time was 6 hours. After ion nitriding, the nitrogen and hydrogen valves were closed, and the voltage and current parameters were adjusted. The ion oxygenation temperature was set to 400℃, a single-stage oxygenation process was used, with a flow rate of 6 L / min, and oxygenation for 15 minutes. The furnace atmosphere pressure was 100 Pa. After ion percolation, once the furnace temperature drops below 100℃, the sample is removed from the furnace and placed into an ion vacuum coating furnace. The coating targets are Si, Cr, and CrAl. The voltage and current are adjusted to initiate ignition, followed by argon gas for ion sputtering at a flow rate of 500 mL / min. After 10 minutes of sputtering, nitrogen gas is introduced at a flow rate of 800 mL / min. The coating temperature is set to 500℃, the bias voltage to 70V, and the vacuum level to 10. -4 Pa, heat treatment time is 6h. After vacuum coating is completed, the nitrogen and argon valves are closed. After the furnace temperature drops below 100℃, the sample is taken out of the furnace and its surface is polished to ensure that the final surface roughness Ra≤0.2μm.

[0041] The bonding strength, thickness, and hardness of the composite reinforcing layer were analyzed according to standards JB / T 8554, JB / T 7707, and ISO14477-1, respectively. Table 1 shows that the reinforcing layer thickness is 54 μm, the surface hardness is 3790 HV, 3780 HV, and 3800 HV, and the bonding strength is only 70 N. This is mainly because, although a nitriding layer and an oxide layer were added, the ion percolation process was a single-stage process of 6 L / min with a 15-min holding time. There was no gradient control of the oxygen flow rate, leading to continuous stress buildup within the oxide layer during the percolation process. Additionally, other oxide phases besides iron(III) oxide were generated, which could not effectively improve corrosion resistance. The loose, porous structure within the nitriding layer was not fully optimized, ultimately resulting in low bonding strength between the nitriding layer and the nanocomposite ceramic layer, leading to poor bonding strength between the surface nitride coating and the substrate. According to standard ASTM... Friction and wear tests were conducted on the reinforced layer using a reciprocating friction method. The test temperature was room temperature, the load was set at 80 N, the reciprocating length was 5 mm, the running speed was 800 t / min, and the wear time was 10 min. The results in Table 1 show that the frictional weight loss was 47 × 10⁻⁶. -3 mm 3The coefficient of friction is 0.60, indicating that its wear resistance is generally poor. This is mainly because the reinforcing layer is not firmly bonded to the substrate, and the wear resistance is not significantly improved. An electrochemical corrosion experiment was conducted on the reinforcing layer with a NaCl salt solution concentration of 3.5%. Figure 2 The self-corrosion potential is approximately -400mV. Observation of the surface morphology after corrosion revealed no peeling or flaking, indicating superior corrosion resistance compared to the single-layer reinforcement in the comparative example. In summary, this composite reinforcement layer exhibits high hardness but only moderate wear and corrosion resistance. This is primarily due to the porous surface defects of the nitride layer and the poor bonding strength between the nitride coating and the nitride layer, which limits the overall performance of the composite reinforcement layer.

[0042] Example 1

[0043] 316 stainless steel was selected as the experimental substrate material. Its surface was ground, polished, ultrasonically cleaned with ions, and dried. Then, it was placed in an ion nitriding furnace. When the vacuum was reduced to <20 Pa, the voltage and current were adjusted to initiate ignition. Hydrogen gas was then introduced for ion sputtering. After 5 minutes of sputtering, nitrogen gas was introduced, with a nitrogen-to-hydrogen ratio of 3:1. Nitriding was started when the temperature reached the nitriding temperature of 400℃. The nitriding atmosphere pressure was set to 100 Pa, and the holding time was 6 hours. After ion nitriding, the nitrogen and hydrogen valves were closed, and the voltage and current parameters were adjusted. The ion oxygenation temperature was set to 400℃, and the oxygen flow rate was set to 2 L / min for 5 minutes; 4 L / min for 5 minutes; and 6 L / min for 5 minutes. The furnace atmosphere pressure was 100 Pa. After ion permeation, the sample was placed in an ion vacuum coating furnace. The coating targets were Si, Cr, and CrAl. The voltage and current were adjusted to initiate ignition. Then, argon gas was introduced for ion sputtering at a flow rate of 500 mL / min. After 10 minutes of sputtering, nitrogen gas was introduced at a flow rate of 800 mL / min. The coating temperature was set to 500℃, the bias voltage to 70V, and the vacuum level to 10. -4 Pa, heat treatment time is 6h. After vacuum coating is completed, the nitrogen and argon valves are closed. After the furnace temperature drops below 100℃, the sample is taken out and its surface is polished to ensure that the final surface roughness Ra≤0.2μm.

[0044] The bonding strength, thickness, and hardness of the composite reinforcing layer were analyzed according to standards JB / T 8554, JB / T 7707, and ISO14477-1. Table 1 shows that the reinforcing layer thickness is 56 μm, surface hardness is 3820 HV, 3810 HV, and 3800 HV, and bonding strength is 110 N, more than twice that of other reinforcing layers. This is mainly due to the addition of a nitriding layer as a load-bearing layer and the design of a three-stage ion percolation process with flow rates set at 2 L / min, 4 L / min, and 6 L / min. This three-stage percolation method ensures low residual stress within the oxide layer, allowing the oxide layer to firmly grow on the nitriding layer. The controlled step-percolation process ensures that iron(III) oxide is the main phase, reducing the nitriding white layer and avoiding porous defects on the nitriding layer surface, resulting in a denser nitriding layer structure, improved bonding strength between the nitride coating and the nitriding layer, and guaranteed bonding strength of the composite reinforcing layer. According to standard ASTM... Friction and wear tests were conducted on the reinforced layer using a reciprocating friction method. The test temperature was room temperature, the load was set at 80 N, the reciprocating length was 5 mm, the running speed was 800 t / min, and the wear time was 10 min. The results in Table 1 show that the frictional weight loss was only 21*10. -3 mm 3 The coefficient of friction is 0.54, exhibiting optimal wear resistance. This is primarily due to the strong bond between the reinforced layer and the substrate, resulting in high surface hardness and significantly improved wear resistance. Electrochemical corrosion experiments were conducted on the reinforced layer using a 3.5% NaCl salt solution. Figure 2 It can be seen that when the corrosion potential is increased to -300mV, no peeling or flaking is observed on the surface morphology after corrosion, indicating good corrosion resistance. In summary, by optimizing the process and improving the microstructure of the composite reinforcement layer, its bonding strength, surface hardness, and friction coefficient are improved. This composite reinforcement layer combines the performance advantages of each individual reinforcement layer, exhibiting superior overall wear and corrosion resistance.

[0045] Example 2

[0046] 316 stainless steel was selected as the experimental substrate material. Its surface was ground, polished, ultrasonically cleaned with ions, and dried. Then, it was placed in an ion nitriding furnace. When the vacuum was reduced to <20 Pa, the voltage and current were adjusted to initiate ignition. Hydrogen gas was then introduced for ion sputtering. After sputtering for 20 minutes, nitrogen gas was introduced, with the nitrogen-to-hydrogen ratio adjusted to 3:1. Nitriding was started when the temperature reached the nitriding temperature of 300℃. The nitriding atmosphere pressure was set to 150 Pa, and the holding time was 7 hours. After ion nitriding, the nitrogen and hydrogen valves were closed, and the voltage and current parameters were adjusted. The ion oxygenation temperature was set to 300℃, and the oxygen flow rate was set to 3 L / min for 5 minutes; the oxygen flow rate was set to 5 L / min for 5 minutes; the oxygen flow rate was set to 5 L / min for 5 minutes, and the furnace atmosphere pressure was 100 Pa. After ion permeation, the sample was placed in an ion vacuum coating furnace. The coating targets were Si, Cr, and CrAl. The voltage and current were adjusted to initiate ignition. Then, argon gas was introduced for ion sputtering at a flow rate of 600 mL / min. After 20 minutes of sputtering, nitrogen gas was introduced, with a flow rate of 600 mL / min. The coating temperature was set to 450℃, the bias voltage to 100V, and the vacuum level to 10. -3 Pa, heat treatment time is 7h. After vacuum coating is completed, the nitrogen and argon valves are closed. After the furnace temperature drops below 100℃, the sample is taken out and its surface is polished to ensure that the final surface roughness Ra≤0.2μm.

[0047] The bonding strength, thickness, and hardness of the composite reinforcing layer were analyzed according to standards JB / T 8554, JB / T 7707, and ISO14477-1, respectively. Table 1 shows that the reinforcing layer thickness is 52 μm, with surface hardnesses of 3796 HV, 3802 HV, and 3788 HV, and a bonding strength of 107 N, more than twice that of other reinforcing layers. This is also attributed to the addition of a nitriding layer as a load-bearing layer. Furthermore, the design of a three-stage ion percolation process, with flow rates set at 3 L / min, 5 L / min, and 5 L / min respectively, ensures low residual stress within the oxide layer, allowing it to firmly grow on the nitriding layer. The controlled step-percolation process ensures that iron(III) oxide is the main phase, reducing the nitriding white layer and avoiding surface porosity defects, resulting in a denser nitriding layer structure. This improves the bonding strength between the nitride coating and the nitriding layer, guaranteeing the bonding strength of the composite reinforcing layer. According to standard ASTM... Friction and wear tests were conducted on the reinforced layer using a reciprocating friction method. The test temperature was room temperature, the load was set at 80 N, the reciprocating length was 5 mm, the running speed was 800 t / min, and the wear time was 10 min. The results in Table 1 show that the frictional weight loss was only 25*10. -3 mm 3The coefficient of friction is 0.55, exhibiting optimal wear resistance. This is primarily due to the strong bond between the reinforced layer and the substrate, resulting in high surface hardness and significantly improved wear resistance. Electrochemical corrosion experiments were conducted on the reinforced layer using a 3.5% NaCl salt solution. Figure 2 It can be seen that when the corrosion potential is increased to -350mV, no peeling or flaking is observed on the surface morphology after corrosion, indicating relatively superior corrosion resistance. In summary, by optimizing the process and improving the microstructure of the composite reinforcement layer, its bonding strength, surface hardness, and friction coefficient are improved. This composite reinforcement layer combines the performance advantages of each individual reinforcement layer, exhibiting superior overall wear and corrosion resistance.

[0048] Table 1 Performance test results of the reinforcement layer

[0049]

[0050] Based on the above-described preferred embodiments of the present invention, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A method for preparing a highly wear-resistant and corrosion-resistant composite reinforcement layer on a metal surface, characterized in that: (1) First, the steel substrate surface is ground, polished and ion cleaned. Then, the steel substrate is placed in the ion nitriding furnace, vacuumed to a certain degree, hydrogen is introduced for ion sputtering, and then nitriding medium is introduced for ion nitriding. (2) After nitriding, an oxidizing medium is introduced to carry out a three-stage ion oxygenation process; the ion oxygenation medium is air; the ion oxygenation temperature is 250℃~400℃, the oxygenation flow rates are 2L / min-3L / min, 4L / min-5L / min, 5L / min-6L / min, and the furnace atmosphere pressure is 50Pa~150Pa. (3) Finally, the sample is placed in a vacuum coating machine, a deposition atmosphere medium is introduced, and a nanostructured composite ceramic layer is deposited using unbalanced magnetron sputtering technology. The nanostructured composite ceramic layer is a composite layer structure of chromium nitride layer and multi-component nitride coating.

2. The method for preparing the high wear-resistant and corrosion-resistant composite reinforcement layer on the metal surface according to claim 1, characterized in that: Step (1) Introduce hydrogen gas for sputtering for 5 min to 30 min; the nitriding medium is a mixture of nitrogen and hydrogen gas, the ion nitriding temperature is 250℃ to 500℃, the holding time is 1 h to 9 h, and the atmosphere pressure inside the nitriding furnace is low pressure 20 Pa to 150 Pa.

3. The method for preparing the high wear-resistant and corrosion-resistant composite reinforcement layer on the metal surface according to claim 1, characterized in that: The composite layer of chromium nitride layer and multi-component nitride layer is a CrN-CrAlSiN nanocomposite coating.

4. The method for preparing the high wear-resistant and corrosion-resistant composite reinforcement layer on the metal surface according to claim 1, characterized in that: The nitrided layer after ion nitriding has a hardness of 1000HV~1300HV and a thickness of 20μm~300μm; The thickness of the oxygen-permeable layer is 1μm~3μm; The hardness of the nanostructured composite ceramic layer is 3000HV~4000HV, and the thickness is 1μm~10μm.

5. The method for preparing the high wear-resistant and corrosion-resistant composite reinforcement layer on the metal surface according to claim 1, characterized in that: The total thickness of the composite reinforcement layer is 22μm~310μm, and the surface roughness Ra≤0.2μm.

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