Preparation method of low-temperature plasma plating and permeating modified layer on surface of metal mold

Abstract

The invention discloses a preparation method of a low-temperature plasma plating and permeating modified layer on the surface of a metal mold. The preparation method comprises the following steps: S1, precise pretreatment of a base body: sequentially carrying out mechanical grinding and polishing and ultrasonic cleaning on the base body, and then drying and putting the base body in a vacuum chamber; s2, plasma activation: after vacuumizing, introducing mixed gas of argon and hydrogen, generating glow discharge under the action of a pulse power supply, and performing sputtering activation on the surface of the substrate; s3, gradient transition layer plasma deposition is conducted, specifically, a pulse direct-current plasma source is adopted, a Ti target and a Cr target serve as sputtering sources, and a transition layer with components changing in a gradient mode is prepared; s4, plating and permeating a multi-element synergistic functional layer: preparing the functional layer by adopting a radio frequency-pulse direct-current composite plasma source, namely a Ti target, a Cr target, a Si-Al alloy target and a rare earth element target through synergistic sputtering; and S5, post-treatment optimization: performing vacuum cooling to room temperature after low-temperature annealing treatment to obtain a final modified layer. The permeation modified layer prepared by the method has high binding force, high hardness, high wear resistance and salt spray corrosion resistance.

Description

Technical Field

[0001] This invention relates to the field of surface technology, and in particular to a method for preparing a low-temperature plasma deposition modification layer on the surface of a metal mold. Background Technology

[0002] Metal molds are widely used in industries such as machinery manufacturing, automobiles, and electronics. During stamping, die casting, and injection molding, they must withstand high temperatures, high pressures, friction, and thermal cycling shocks. Therefore, their surface properties directly determine the mold's service life and the precision of the molded parts. Traditional surface modification technologies for metal molds have significant drawbacks. For example, chemical plating relies on strong acid and alkali solutions, easily causing environmental pollution and hydrogen embrittlement of the substrate; physical vapor deposition (PVD), while forming dense coatings, lacks sufficient adhesion to the substrate and is prone to peeling during thermal cycling; thermal spraying technology, due to its high coating porosity, struggles to meet the surface quality requirements of precision molds; traditional thermal diffusion methods such as nitriding and carburizing involve high processing temperatures, easily leading to softening and deformation of the mold substrate, and even requiring secondary processing, making them unsuitable for precision molds and molds already heat-treated to high hardness.

[0003] These individual technologies struggle to simultaneously achieve both "high bonding strength" and "excellent surface properties." The surface properties of a simple diffusion layer are insufficient; the adhesion of a simple PVD coating is a weak point; and when combining the two technologies, if performed step-by-step in different devices, the exposure and transfer of intermediate steps can lead to interfacial oxidation and contamination, severely impacting interlayer adhesion. Furthermore, the high processing temperature limits its application to more precision molds and specific materials. In contrast, low-temperature plasma deposition technology, with its advantages of low processing temperature, low environmental pollution, and excellent modified layer performance, has become one of the mainstream technologies for mold surface modification.

[0004] Existing low-temperature plasma plating and infiltration technologies suffer from drawbacks such as weak adhesion between the modified layer and the substrate, poor compositional uniformity, limited functionality, insufficient process stability, and susceptibility to substrate softening. For example, plasma carburizing and nitriding can only form a single infiltration layer, failing to balance hardness and toughness. Specifically, TiN single-layer plating and infiltration technology, while improving mold hardness, suffers from weak adhesion to the substrate and insufficient corrosion resistance.

[0005] Therefore, there is an urgent need to provide a method for preparing a low-temperature plasma plating modification layer on the surface of a metal mold that combines high bonding strength, high hardness and toughness, and high wear resistance and anti-adhesion. Summary of the Invention

[0006] The purpose of this invention is to provide a method for preparing a low-temperature plasma infiltration modified layer on the surface of a metal mold, so as to solve the problems mentioned in the background art, such as the inability of a single infiltration layer to balance hardness and toughness, weak bonding force, and insufficient corrosion resistance.

[0007] To achieve the above objectives, the present invention provides the following technical solution: A method for cultivating selenium-enriched edible fungi includes the following steps: S1. Precision pretreatment of the substrate: The metal mold substrate is mechanically ground and polished, and ultrasonically cleaned in sequence. After cleaning, it is dried at 80~100℃ and then placed into the vacuum chamber of the plasma plating equipment.

[0008] S2. Plasma activation: The vacuum chamber is evacuated to a vacuum, and a mixture of argon and hydrogen is introduced. Under the action of a pulse power supply, a glow discharge is generated to sputter and activate the mold surface.

[0009] S3. Gradient transition layer plasma deposition: After activation, the argon-hydrogen mixture is turned off, and a pulsed DC plasma source is used with Ti and Cr targets as sputtering sources to prepare a transition layer with varying compositional gradients.

[0010] S4. Multi-component synergistic functional layer deposition: The functional layer is prepared by synergistic sputtering of a radio frequency-pulsed DC composite plasma source, namely Ti target, Cr target, Si-Al alloy target and rare earth element target.

[0011] S5. Post-treatment optimization: After the plating is completed, a low-temperature annealing treatment is performed in the plasma treatment chamber, followed by vacuum cooling to room temperature to obtain the final modified layer.

[0012] As a preferred technical solution of the present invention, in S1, the mechanical polishing is performed using diamond polishing paste to achieve a mirror finish; The ultrasonic cleaning process involves sequentially cleaning with acetone, alcohol, and deionized water for 15-20 minutes each.

[0013] In a preferred embodiment of the present invention, in step S2, the gas flow ratio of argon to hydrogen is 3~5:1; The pulse power supply has a bias voltage of -500~-800V, a duty cycle of 30~50%, a vacuum degree of 1~5Pa, and an activation time of 30~60min.

[0014] As a preferred embodiment of the present invention, in step S3, during the deposition process, the pulse frequency is 10~30kHz, the duty cycle is 20~40%, the vacuum degree is 1~5Pa, the temperature is 250~350℃, and the bias voltage is set to -50~-150V.

[0015] As a preferred technical solution of the present invention, in S3, the thickness of the transition layer is 1~3μm, wherein from the substrate side to the functional layer side, the Ti element content decreases from 80~90at% to 20~30at%, and the Cr element content increases from 10~20at% to 70~80at%.

[0016] As a preferred embodiment of the present invention, in S4, the atomic percentage of each element in the control functional layer is Cr 40~60at%, Si 10~20at%, Al 5~15at%, rare earth elements 0.5~2at%, and the remainder is Ti; The atomic ratio of Si to Al in the Si-Al alloy target is 2:1; The rare earth element is either Ce or La, and is introduced by doping a rare earth oxide target material, wherein the mass fraction of CeO2 or La2O3 in the rare earth oxide target material is 5-10%. During the plating process, a mixture of nitrogen and methane gas needs to be introduced, with a gas flow rate ratio of 2 to 4:1. The plating power is 600~900W, the temperature is 300~400℃, and the time is 20~40min.

[0017] As a preferred embodiment of the present invention, the thickness of the functional layer is 4~7μm.

[0018] As a preferred embodiment of the present invention, in step S5, the annealing temperature during low-temperature annealing is 200~250℃ and the time is 10~15min.

[0019] Compared with the prior art, the beneficial effects of the present invention are: 1. This invention achieves a significant leap in the overall performance of the modified layer through the synergistic effect of multiple elements and structural design. In the functional layer, Cr forms the basic framework, ensuring fundamental wear resistance and stability; Si significantly enhances hardness through solid solution strengthening, while Al enhances passivation capabilities to optimize corrosion resistance; rare earth elements (Ce or La) further improve compositional uniformity and microstructure density by refining grains and suppressing defect formation; and Ti acts as a transition and connecting link, coordinating interfacial compatibility among the elements. This synergistic effect overcomes the functional limitations of single elements or simple multi-element systems, enabling the modified layer to simultaneously possess high hardness, wear resistance exceeding that of traditional technologies, and salt spray corrosion resistance. It solves the pain points of existing technologies such as "imbalance between hardness and toughness" and "difficulty in achieving both wear resistance and corrosion resistance." Furthermore, the structural coordination of the multi-element synergy and gradient transition layer ensures high performance while maintaining high bonding strength, avoiding the problem of excellent performance but easy detachment. It is suitable for various scenarios such as cold working, hot working, and plastic molds, significantly extending the service life of molds.

[0020] 2. This invention achieves surface optimization through a three-step synergistic process of plasma activation pretreatment. Mechanical grinding to a mirror finish reduces initial defects, ultrasonic cleaning thoroughly removes oil and impurities, and then argon-hydrogen mixed plasma sputtering activation further cleans residual contaminants on the surface and forms a micro-nano-scale rough structure through micro-etching. This rough surface increases the contact area with subsequent transition layers, while plasma activation enhances the substrate surface energy, making it easier for transition layer atoms to adsorb and form chemical bonds, laying the foundation for subsequent coating bonding.

[0021] 3. The composition gradient transition layer design in this invention specifically addresses the interfacial stress problem. Due to the significant material difference between the mold substrate and the functional layer (e.g., the substrate is steel, while the functional layer contains a large amount of Cr, Si, etc.), direct bonding is prone to stress concentration and delamination due to abrupt performance changes. However, in the transition layer, Ti gradually decreases from 80-90 at% to 20-30 at%, while Cr gradually increases from 10-20 at% to 70-80 at%, allowing for a gradual transition in composition, hardness, and other properties from the substrate to the functional layer. This significantly reduces abrupt changes in physicochemical properties at the interface and effectively alleviates stress accumulation. Combined with plasma activation, the bonding force between the modified layer and the substrate is significantly improved, preventing coating delamination under long-term stress and thermal cycling conditions. Simultaneously, it provides stable support for the subsequent functional layer, ensuring the full utilization of high hardness, wear resistance, and other properties, thus extending the mold's service life. Attached Figure Description

[0022] Figure 1 This is a flowchart of a method for preparing a low-temperature plasma deposition and infiltration modification layer on the surface of a metal mold according to the present invention. Detailed Implementation

[0023] 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 some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings.

[0025] To achieve a significant improvement in the overall performance of the modified layer, a multi-element synergistic design and gradient structure construction systematically addressed the core pain points of existing technologies: the imbalance between hardness and toughness, and the difficulty in simultaneously achieving wear resistance and corrosion resistance. In terms of elemental functional design, a multi-element system was constructed, with Cr as the basic framework, Si and Al as strengthening and protective units, rare earth elements (Ce / La) as microstructure optimizers, and Ti as the interface synergistic link. Cr forms the backbone of the modified layer, providing reliable basic wear resistance and thermal stability. Si significantly enhances the macroscopic hardness and resistance to plastic deformation of the modified layer through a strong solid solution strengthening effect. Al preferentially forms a dense passivation film in corrosive environments, fundamentally enhancing the corrosion resistance of the modified layer, especially its resistance to salt spray corrosion. Rare earth elements (Ce / La), as key "microstructure regulators," effectively refine grains, purify grain boundaries, and inhibit the initiation of defects such as microcracks through their unique surface activity, thereby significantly improving the uniformity and density of the modified layer's microstructure. Ti acts as a "bridge" between components, improving interfacial compatibility and bonding strength between different phases, ensuring the structural integrity of the multi-element system. This careful elemental formulation produces a synergistic effect of "1+1>2," overcoming the functional limitations of single-element or simple multi-element systems. This synergistic effect is further combined with the gradient transition layer structure, achieving a smooth transition from the matrix to the surface in terms of composition, avoiding abrupt performance changes; and structurally, forming an organic combination of strong support and ultra-hard, wear-resistant surface. Through the dual design of composition and structure, extremely high bonding force is ensured between the modified layer and the mold matrix, fundamentally eliminating the industry problem of easy peeling of high-performance coatings. It can be widely used in various harsh working conditions such as cold working, hot working, and plastic molds, significantly extending its service life.

[0026] To achieve a high-strength bond between the modified layer and the mold substrate, a three-step synergistic process of plasma activation pretreatment was designed to systematically optimize the substrate surface condition and provide an ideal base for subsequent coatings. Precision mechanical grinding achieves a mirror finish on the mold surface, effectively eliminating microscopic unevenness and machining defects of the original surface, providing a uniform and consistent initial surface for subsequent processing. Ultrasonic cleaning thoroughly removes oil, dust, and other organic and inorganic impurities adhering to the surface, ensuring the chemical purity of the substrate surface and preventing contaminants from adversely affecting subsequent interfacial bonding. Argon-hydrogen plasma sputtering activation constructs an active interface; this is the core step of the pretreatment. The pretreated mold is placed in a vacuum chamber, and an argon-hydrogen mixed gas is introduced to excite plasma. High-energy plasma bombards the surface with ions (sputtering), stripping away atomic-level adsorbates that failed to be removed in the first two steps, forming a uniform micro-nano-scale rough structure through micro-etching, significantly increasing the substrate surface energy, and generating numerous dangling bonds, thus transforming it into a highly active state. Therefore, these three steps form a progressive optimization from "macro-level smoothing" to "chemical cleaning" and then to "micro-level activation". Ultimately, the pretreated surface not only increases the physical contact area with the subsequent transition layer due to the micro-nano roughness, but also greatly promotes the adsorption of transition layer atoms and the formation of strong chemical bonds (such as metallic bonds and covalent bonds) due to the high surface energy and high activity. This lays an indispensable physical and chemical foundation for the high bonding force and long service life of the modified layer.

[0027] The mold substrate (such as steel) and the functional layer rich in elements such as Cr and Si have significant differences in physical and chemical properties. If they are directly bonded, the interface will generate huge internal stress due to the abrupt changes in parameters such as thermal expansion coefficient, elastic modulus, and hardness. This can easily lead to coating peeling during service stress or thermal cycling. To eliminate this bottleneck, a precise compositional gradient transition layer is designed. In this transition layer, the main elements change in a continuous gradient: the Ti content gradually decreases from 80-90 at% on the adjacent substrate side to 20-30 at% on the functional layer side; at the same time, the Cr content increases in the opposite gradient from the initial 10-20 at% to 70-80 at%. This design creates a buffer zone with no abrupt changes in composition, hardness, and thermodynamic properties, achieving a smooth and coordinated transition from a tough substrate to a high-hardness functional layer. This gradient structure, combined with the active surface formed by plasma activation, produces a dual strengthening effect. On the one hand, the compositional gradient effectively alleviates the interfacial stress accumulated due to performance mismatch; on the other hand, the plasma-activated surface provides strong atomic-level bonding force for the initial growth of the gradient layer. The synergy between the two results in a significant leap in the bonding strength between the modified layer and the substrate, effectively resisting long-term load impacts and thermal fatigue. This design not only fundamentally prevents coating peeling but also provides a stable and reliable support base for subsequent functional layers, ensuring that their excellent properties such as high hardness and wear resistance are fully utilized, thereby significantly extending the service life of the mold under harsh working conditions.

[0028] Please see Figure 1 A method for preparing a low-temperature plasma deposition modified layer on the surface of a metal mold includes the following steps: S1. Precision pretreatment of the substrate: The metal mold substrate is mechanically ground and polished, ultrasonically cleaned, and then dried at 80~100℃ after cleaning, and then placed in the vacuum chamber of the plasma deposition equipment; S2. Plasma activation: The vacuum chamber is evacuated to a vacuum, and a mixture of argon and hydrogen is introduced. Under the action of a pulsed power supply, glow discharge is generated to activate the mold surface by sputtering; S3. Gradient transition layer plasma deposition: After activation, the argon-hydrogen mixture is turned off, and a pulsed DC plasma source is used with Ti and Cr targets as sputtering sources. By gradually adjusting the power ratio of the two targets, a transition layer with a compositional gradient is prepared; S4. Multi-element synergistic functional layer deposition: A multi-element synergistic functional layer is prepared by synergistic sputtering of a radio frequency-pulsed DC composite plasma source, namely Ti target, Cr target, Si-Al alloy target and rare earth element target; S5. Post-treatment optimization: After deposition, a low-temperature annealing treatment is performed in the plasma treatment chamber, followed by vacuum cooling to room temperature to obtain the final modified layer.

[0029] All raw materials used in this invention are commercially available.

[0030] Example 1

[0031] A method for preparing a low-temperature plasma deposition modified layer on the surface of a metal mold includes the following steps: S1. Precision pretreatment of the substrate: The metal mold substrate is first treated with diamond polishing paste to a mirror finish, and then ultrasonically cleaned with acetone, alcohol and deionized water for 20 minutes each. After cleaning, it is dried at 100°C and then placed in the vacuum chamber of the plasma plating equipment. S2. Plasma activation: The vacuum chamber is evacuated to a vacuum degree of 5 Pa, and a mixture of argon and hydrogen gas (the gas flow ratio of argon to hydrogen is 5:1) is introduced. Under the action of the pulse power supply, glow discharge is generated, wherein the bias voltage of the pulse power supply is -800V and the duty cycle is 50%. The mold surface is sputtered and activated for 60 min. S3. Gradient transition layer plasma deposition: After activation, the argon-hydrogen mixture was shut off, and a pulsed DC plasma source was used with a pulse frequency of 30kHz, a duty cycle of 40%, a vacuum of 5Pa, a temperature of 350℃, and a bias voltage of -150V. Using Ti and Cr targets as sputtering sources, a transition layer with a thickness of 3μm was prepared. On the substrate side, the Ti content was 90at% and the Cr content was 10%, while on the functional layer side, the Ti content was 30at% and the Cr content was 70%. S4. Multi-element synergistic functional layer deposition: A radio frequency-pulsed DC composite plasma source was used at a power of 900W and a temperature of 400℃, with a mixture of nitrogen and methane gas (nitrogen to methane gas flow rate ratio of 4:1). Ti target, Cr target, Si-Al alloy target (Si to Al atomic ratio of 2:1) and La2O3 target (La2O3 mass fraction of 10%) were used as sputtering sources. The deposition was carried out for 40 min, and the atomic percentage of each element in the functional layer was controlled to be Cr 60at%, Si 20at%, Al 15at%, La 2at%, and the remainder was Ti, to prepare a functional layer with a thickness of 7μm. S5. Post-treatment optimization: After the plating is completed, a low-temperature annealing treatment is performed in the plasma treatment chamber at a temperature of 250°C for 15 minutes. Then, the mixture is vacuum cooled to room temperature to obtain the final modified layer.

[0032] Example 2

[0033] A method for preparing a low-temperature plasma deposition modified layer on the surface of a metal mold includes the following steps: S1. Precision pretreatment of the substrate: The metal mold substrate is first treated with diamond polishing paste to a mirror finish, and then ultrasonically cleaned with acetone, alcohol and deionized water for 15 minutes each. After cleaning, it is dried at 80°C and then placed in the vacuum chamber of the plasma plating equipment. S2. Plasma activation: The vacuum chamber is evacuated to a vacuum degree of 1 Pa, and a mixture of argon and hydrogen gas (the gas flow ratio of argon to hydrogen is 3:1) is introduced. Under the action of the pulse power supply, glow discharge is generated, wherein the bias voltage of the pulse power supply is -500V and the duty cycle is 30%. The mold surface is sputtered and activated for 30 min. S3. Gradient transition layer plasma deposition: After activation, the argon-hydrogen mixture was shut off, and a pulsed DC plasma source was used with a pulse frequency of 10kHz, a duty cycle of 20%, a vacuum degree of 1Pa, a temperature of 250℃, and a bias voltage of -50V. Using Ti and Cr targets as sputtering sources, a transition layer with a thickness of 1μm was prepared. On the substrate side, the Ti content was 80at% and the Cr content was 20%, while on the functional layer side, the Ti content was 20at% and the Cr content was 80%. S4. Multi-element synergistic functional layer deposition: A radio frequency-pulsed DC composite plasma source was used at a power of 600W and a temperature of 300℃, with a mixture of nitrogen and methane gas (nitrogen to methane gas flow rate ratio of 2:1). Ti target, Cr target, Si-Al alloy target (Si and Al atomic ratio of 2:1) and La2O3 target (La2O3 mass fraction of 5%) were used as sputtering sources. The deposition was carried out for 20 minutes, and the atomic percentage of each element in the functional layer was controlled to be Cr 40at%, Si 10at%, Al 5at%, La 0.5at%, with the remainder being Ti, to prepare a functional layer with a thickness of 4μm. S5. Post-treatment optimization: After the plating is completed, a low-temperature annealing treatment is performed in the plasma treatment chamber at a temperature of 200°C for 10 minutes. Then, the mixture is vacuum cooled to room temperature to obtain the final modified layer.

[0034] Example 3

[0035] A method for preparing a low-temperature plasma deposition modified layer on the surface of a metal mold includes the following steps: S1. Precision pretreatment of the substrate: The metal mold substrate is first treated with diamond polishing paste to a mirror finish, and then ultrasonically cleaned with acetone, alcohol and deionized water for 17 minutes each. After cleaning, it is dried at 90°C and then placed in the vacuum chamber of the plasma plating equipment. S2. Plasma activation: The vacuum chamber is evacuated to a vacuum degree of 2.5 Pa, and a mixture of argon and hydrogen gas (argon to hydrogen gas flow rate ratio of 4:1) is introduced. Under the action of a pulse power supply, glow discharge is generated, wherein the bias voltage of the pulse power supply is -650V and the duty cycle is 40%. The mold surface is sputtered and activated for 45 min. S3. Gradient transition layer plasma deposition: After activation, the argon-hydrogen mixture was shut off, and a pulsed DC plasma source was used with a pulse frequency of 20kHz, a duty cycle of 30%, a vacuum degree of 2.5Pa, a temperature of 300℃, and a bias voltage of -100V. Using Ti and Cr targets as sputtering sources, a transition layer with a thickness of 2μm was prepared. On the substrate side, the Ti content was 85at% and the Cr content was 15%, while on the functional layer side, the Ti content was 25at% and the Cr content was 75%. S4. Multi-element synergistic functional layer deposition: A radio frequency-pulsed DC composite plasma source was used at a power of 750W and a temperature of 350℃, with a mixture of nitrogen and methane gas (nitrogen to methane gas flow rate ratio of 3:1). Ti target, Cr target, Si-Al alloy target (Si to Al atomic ratio of 2:1) and La2O3 target (La2O3 mass fraction of 7.5%) were used as sputtering sources. The deposition was carried out for 30 min, and the atomic percentage of each element in the functional layer was controlled to be Cr 50at%, Si 15at%, Al 10at%, La 1.5at%, with the remainder being Ti, to prepare a functional layer with a thickness of 5.5μm. S5. Post-treatment optimization: After the plating is completed, a low-temperature annealing treatment is performed in the plasma treatment chamber at a temperature of 225°C for 12 minutes. Then, the mixture is vacuum cooled to room temperature to obtain the final modified layer.

[0036] Comparative Example 1: The difference from Example 1 is that the precision pretreatment step of the substrate is removed.

[0037] Comparative Example 2: The difference from Example 1 is that the gradient transition layer plasma deposition step is removed.

[0038] Comparative Example 3: The difference from Example 1 is that the multi-functional synergistic permeation step is removed.

[0039] The modified layers prepared in Examples 1, 2, and 3 and Comparative Examples 1, 2, and 3 were subjected to performance tests.

[0040] The modified layers prepared in Examples 1, 2, and 3 and Comparative Examples 1, 2, and 3 were tested for surface hardness using the national standard GB / T4340.1-2021 "Vickers Hardness Test"; the salt spray resistance time of the modified layers was tested using the standard GB / T10125-2021; the wear resistance of the modified layers was tested using the standard GB / T23988-2009; and the bonding strength of the coatings was tested using the standard GB / T5270-2024. The results are shown in Table 1.

[0041] Table 1: Performance Indicators of the Infiltration Modified Layers Prepared in Examples and Comparative Examples

[0042] As shown in Table 1, the hardness of the infiltration-modified layers prepared in Examples 1, 2, and 3 is generally higher than that of Comparative Examples 1, 2, and 3, with the highest hardness reaching HV1600, significantly superior to all the comparative example groups. Furthermore, the salt spray corrosion resistance time, wear resistance, and bonding strength of the example groups are also higher than those of the comparative example groups. Therefore, the method for preparing the infiltration-modified layer of metal molds provided by this invention can significantly improve the hardness, wear resistance, corrosion resistance, and bonding strength of the metal surface.

[0043] The precision pretreatment of the substrate involves mechanical grinding to a mirror finish to reduce surface defects, and ultrasonic cleaning to thoroughly remove oil and impurities, providing a clean and smooth adhesion base for subsequent coatings. This avoids weak points in adhesion caused by impurities and enhances surface activity, ensuring effective bonding between the coating atoms and the substrate, a prerequisite for high adhesion. The gradient transition layer, through a gradient change in Ti and Cr composition (from high Ti on the substrate side to high Cr on the functional layer side), alleviates the interfacial stress caused by material differences (such as hardness and coefficient of thermal expansion) between the substrate and the functional layer. This avoids stress concentration and coating peeling caused by direct bonding, significantly improving adhesion and providing stable support for the functional layer, ensuring wear resistance. The multi-functional layer, as the core performance carrier, features synergistic effects from multiple components. Cr forms a hard phase with nitrogen and carbon, laying the foundation for high hardness; Si refines the grains; and Al forms a dense oxide film, respectively enhancing wear resistance and corrosion resistance. Rare earth elements optimize the uniformity of the microstructure and reduce defects. The combination of these three steps gives the modified layer high hardness, strong adhesion, excellent wear resistance, and corrosion resistance—all indispensable.

[0044] In summary, the infiltration-modified layer prepared by the method of the present invention has high bonding strength, high hardness, high wear resistance and salt spray corrosion resistance.

[0045] The above are merely specific embodiments of the present invention, but the technical features of the present invention are not limited thereto. Any simple changes, equivalent substitutions, or modifications made based on the present invention to solve essentially the same technical problems and achieve essentially the same technical effects are all covered within the protection scope of the present invention.

Claims

1. A method for preparing a low-temperature plasma deposition modification layer on the surface of a metal mold, characterized in that, Includes the following steps: S1. Precision pretreatment of the substrate: The metal mold substrate is mechanically ground and polished, and ultrasonically cleaned in sequence. After cleaning, it is dried at 80~100℃ and then placed into the vacuum chamber of the plasma plating equipment. S2. Plasma activation: The vacuum chamber is evacuated to a vacuum, and a mixture of argon and hydrogen is introduced. Under the action of a pulse power supply, a glow discharge is generated to sputter and activate the mold surface. S3. Gradient transition layer plasma deposition: After activation, the argon-hydrogen mixture is turned off, and a pulsed DC plasma source is used with Ti and Cr targets as sputtering sources to prepare a transition layer with varying compositional gradients. S4. Multi-component synergistic functional layer deposition: The functional layer is prepared by synergistic sputtering of a radio frequency-pulsed DC composite plasma source, namely Ti target, Cr target, Si-Al alloy target and rare earth element target; S5. Post-treatment optimization: After the plating is completed, a low-temperature annealing treatment is performed in the plasma treatment chamber, followed by vacuum cooling to room temperature to obtain the final modified layer.

2. The method for preparing a low-temperature plasma deposition modification layer on the surface of a metal mold according to claim 1, characterized in that, In step S1, mechanical polishing is performed using diamond polishing paste to achieve a mirror finish; The ultrasonic cleaning process involves sequentially cleaning with acetone, alcohol, and deionized water for 15-20 minutes each.

3. The method for preparing a low-temperature plasma deposition modification layer on the surface of a metal mold according to claim 1, characterized in that, In S2, the gas flow ratio of argon to hydrogen is 3~5:1; The pulse power supply has a bias voltage of -500~-800V, a duty cycle of 30~50%, a vacuum degree of 1~5Pa, and an activation time of 30~60min.

4. The method for preparing a low-temperature plasma deposition modification layer on the surface of a metal mold according to claim 1, characterized in that, In S3, during the deposition process, the pulse frequency is 10~30kHz, the duty cycle is 20~40%, the vacuum degree is 1~5Pa, the temperature is 250~350℃, and the bias voltage is set to -50~-150V.

5. The method for preparing a low-temperature plasma deposition modification layer on the surface of a metal mold according to claim 1, characterized in that, In S3, the thickness of the transition layer is 1~3μm, wherein from the substrate side to the functional layer side, the Ti element content decreases from 80~90at% to 20~30at%, and the Cr element content increases from 10~20at% to 70~80at%.

6. The method for preparing a low-temperature plasma deposition modification layer on the surface of a metal mold according to claim 1, characterized in that, In S4, the atomic percentage of each element in the control functional layer is 40~60at% for Cr, 10~20at% for Si, 5~15at% for Al, 0.5~2at% for rare earth elements, and the remainder is Ti. The atomic ratio of Si to Al in the Si-Al alloy target is 2:1; The rare earth element is either Ce or La, and is introduced by doping a rare earth oxide target material, wherein the mass fraction of CeO2 or La2O3 in the rare earth oxide target material is 5-10%. During the plating process, a mixture of nitrogen and methane gas needs to be introduced, with a gas flow rate ratio of 2 to 4:

1. The plating power is 600~900W, the temperature is 300~400℃, and the time is 20~40min.

7. The method for preparing a low-temperature plasma deposition modification layer on the surface of a metal mold according to claim 1, characterized in that, The thickness of the functional layer is 4~7μm.

8. The method for preparing a low-temperature plasma deposition modification layer on the surface of a metal mold according to claim 1, characterized in that, In step S5, the annealing temperature during low-temperature annealing is 200~250℃, and the time is 10~15min.

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