Composite material and preparation method therefor, wear-resistant structural component, and electronic device
By using composite materials, including a substrate and a stacked composite wear-resistant layer, on the hinge of the folding phone, the problem of insufficient wear resistance of the hinge material is solved, resulting in a hinge with high wear resistance and long life, which improves the reliability and user experience of the folding phone.
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- HUAWEI TECH CO LTD
- Filing Date
- 2025-05-30
- Publication Date
- 2026-06-04
Smart Images
Figure CN2025098304_04062026_PF_FP_ABST
Abstract
Description
Composite materials and their preparation methods, wear-resistant structural components, electronic equipment
[0001] This application claims priority to Chinese patent application filed on November 26, 2024, with application number 202411719996.1 and title "Composite materials and preparation methods thereof, wear-resistant structural parts, electronic equipment", the contents of which are incorporated herein by reference. Technical Field
[0002] This application relates to the field of materials technology, specifically to composite materials and their preparation methods, wear-resistant structural components, and electronic equipment. Background Technology
[0003] Currently, foldable phones are gradually developing as a new form of smartphone. The core hinge of a foldable phone is responsible for its folding and opening / closing. During this process, it requires a certain holding force and must be able to hover at the open / closed angle, unlike a door lock which lacks holding force and moves freely. To achieve 180-degree folding in the open / closed state, the hinge is primarily made of MIM 17-4 or MIM 420 materials, with a hardness generally between 350HV and 480HV. Since a damping mechanism is necessary during the opening and closing process, this mechanism provides the necessary damping force to ensure the hinge has both opening and closing forces. However, this damping mechanism generates friction. Due to the insufficient wear resistance of current hinge component materials, these components will wear down, causing structural changes. After prolonged use, the hinge's opening and closing damping force decreases, resulting in a poorer bending feel and, in severe cases, damage to the foldable phone's opening and closing function, ultimately affecting the user experience.
[0004] Therefore, existing materials for the hinge cannot meet the requirements for hardness and wear resistance, which in turn affects the reliability of the folding device.
[0005] Application content
[0006] This application proposes a composite material and its preparation method, wear-resistant structural parts, and electronic devices. The composite material has both high hardness and excellent wear resistance and can be applied to shaft parts to improve the reliability of folding devices.
[0007] In a first aspect, this application provides a composite material, including a substrate and a composite wear-resistant layer stacked on the surface of the substrate; the portion of the substrate near the composite wear-resistant layer includes a reinforcing layer, the reinforcing layer including at least one of a carburized layer, a nitrided layer and a carbonitriding layer;
[0008] The composite wear-resistant layer includes a connecting layer, a transition layer, and a TaC film layer sequentially stacked on the surface of the substrate; wherein, the connecting layer includes at least one of a metal layer and a single silicon layer; the transition layer is located between the connecting layer and the TaC film layer, and the material of the transition layer includes at least one of a metal-metal carbide composite and a silicon-silicon carbide composite; the total thickness of the composite wear-resistant layer is greater than or equal to 1 μm, and the Vickers hardness is greater than or equal to 3000 HV.
[0009] The composite material provided in this application has a reinforcing layer near the composite wear-resistant layer. Because the reinforcing layer is doped with nitrogen and / or carbon, the substrate's resistance to plastic deformation is enhanced, improving its strength (yield strength and tensile strength) and hardness. A connecting layer, a transition layer, and a TaC film are sequentially stacked on the surface of the reinforcing layer. The connecting layer enhances the bonding strength between the composite wear-resistant layer and the substrate. The transition layer is made of a composite of metal and metal carbides. The transition layer is relatively softer than the TaC film. Placing the transition layer between the connecting layer and the TaC film allows it to act as a buffer. The hardness of the transition layer increases closer to the TaC film, reaching its maximum value at the TaC film. The TaC film is supported by the transition layer, which also enhances the bonding strength between the TaC film and the connecting layer and the substrate. Furthermore, the surface hardness of the entire composite wear-resistant layer reaches the desired range. Wear-resistant structural components made using this composite material, such as the hinge components of folding phones, achieve excellent yield strength, tensile strength, and wear resistance, thus improving the service life of the wear-resistant structural components.
[0010] In some embodiments, the connecting layer includes at least one of a titanium layer, a zirconium layer, a chromium layer, and a niobium layer. These metals all have high strength (yield strength and tensile strength), which can enhance the overall structural strength of the composite material, and have relatively low density, resulting in good integration with the substrate. This is beneficial for achieving lightweight composite materials and reducing the weight of wear-resistant structural components.
[0011] In some embodiments, the transition layer is made of at least one composite selected from titanium and titanium carbide, zirconium and zirconium carbide, chromium and chromium carbide, and niobium and niobium carbide. Titanium carbide, zirconium carbide, chromium carbide, and niobium carbide all possess good hardness and wear resistance. When dispersed in the metal, they can refine the metal grains, improving the strength, toughness, and wear resistance of the composite wear-resistant material. The hardness of the transition layer is lower than that of the TaC film layer but higher than that of the bonding layer. The presence of the transition layer improves the surface quality of the composite material, further enhancing the wear resistance of the wear-resistant structural components.
[0012] In some embodiments, the metal element in the transition layer is of the same type as the metal element in the connecting layer. Using the same type of metal element helps improve the compatibility between the transition layer and the connecting layer, and can further improve the bonding strength between the transition layer and the connecting layer.
[0013] In some embodiments, the connecting layer includes a single-element silicon layer, and the transition layer is made of a composite of silicon and silicon carbide. The single-element silicon layer serves as a reinforcing layer connecting the substrate. In certain scenarios, the entire composite wear-resistant layer needs to be an insulating layer, and the single-element silicon layer, being a semiconductor with extremely poor conductivity, can achieve insulation between the substrate and the composite wear-resistant layer.
[0014] In some embodiments, the thickness of the reinforcing layer is 5 μm to 30 μm. The thickness of the reinforcing layer is mainly determined by the temperature and time of vapor deposition. Controlling the thickness of the reinforcing layer can ensure that the strength of the substrate is further improved.
[0015] In some embodiments, the thickness of the connecting layer is 100 nm to 2000 nm. Controlling the thickness of the connecting layer within this range is beneficial for improving the bonding strength between the composite wear-resistant layer and the substrate, and for controlling the total thickness of the composite material.
[0016] In some embodiments, the thickness of the transition layer is 100 nm to 2000 nm. The transition layer can serve as a buffer layer to provide support for the TaC film.
[0017] In some embodiments, the thickness of the TaC film is 0.25 μm to 20 μm. Controlling the TaC film thickness within this range can effectively improve the wear resistance of the composite material, and its thickness can be adjusted through a vapor deposition process. When the TaC film thickness is too small, the wear resistance of the composite material decreases, the service life of the wear-resistant structural components is shortened, and substrate cracking is more likely to occur. When the TaC film thickness is too large, the manufacturing cost of the composite material increases, and the overall thickness of the composite material also increases significantly, which is not conducive to the lightweighting of wear-resistant structural components.
[0018] In some embodiments, the composition of the substrate, by weight percentage, includes 18.01% to 21% Co, 16.01% to 19% Ni, 10.01% to 13% Mo, 0% to 2% Ti, 0.05% to 1% Nb, 0.001% to 0.1% C, trace impurity elements totaling no more than 1%, and the balance Fe.
[0019] Trace impurity elements include elements such as Si, Mn, Cr, Al, Y, V, and rare earth elements, with a total weight content not exceeding 1%. Since the content of these trace impurity elements is small, they are unlikely to have a fundamental effect on improving the strength of the material. Therefore, all of these elements other than the main element are collectively referred to as trace impurity elements.
[0020] In some embodiments, the substrate is a high-strength alloy with a yield strength ≥2000MPa and an elongation at break ≥3.5% to provide a substrate with high strength and high toughness.
[0021] In some embodiments, the mass percentage of carbon atoms in the transition layer gradually increases from the side closer to the connecting layer to the side closer to the TaC film. That is, the mass percentage of metal carbides in the region of the transition layer closer to the connecting layer is relatively small, and the transition layer in this region is softer than the TaC film, which helps to improve the adhesion between the composite wear-resistant layer and the substrate, and can reduce the internal stress of the deposited TaC film. As the transition layer approaches the TaC film, the mass percentage of carbon atoms (metal carbides or silicon carbide) in this region gradually increases, and the hardness of the transition layer in this region gradually approaches that of the TaC film, which is beneficial to improving the wear resistance of the composite material.
[0022] In some embodiments, the composite material includes a substrate and a plurality of stacked composite wear-resistant layers, the total thickness of which is 10 μm to 50 μm. Having the thickness of the composite wear-resistant layers within this range allows the composite material to possess both high strength and excellent wear resistance.
[0023] Secondly, this application provides a method for preparing a composite material, comprising the following steps:
[0024] A reinforcing layer is formed by performing a surface strengthening treatment on the substrate, the reinforcing layer comprising at least one of a carburizing layer, a nitriding layer, and a carbonitriding layer;
[0025] At least one composite wear-resistant layer is formed on the surface of the reinforcing layer. The composite wear-resistant layer includes a connecting layer, a transition layer, and a TaC film layer. The total thickness of the composite wear-resistant layer is greater than or equal to 1 μm.
[0026] The preparation method of this application utilizes surface strengthening treatment to form a reinforcing layer on the surface of a substrate, thereby further enhancing the strength of the substrate and enabling it to serve as the load-bearing base for the composite wear-resistant layer. A composite wear-resistant layer is then formed on the surface of the reinforcing layer of the substrate. This composite wear-resistant layer exhibits excellent wear resistance, with a surface Vickers hardness greater than or equal to 3000 HV. The composite material of this application possesses both excellent strength and wear resistance.
[0027] In some embodiments, the step of performing surface strengthening treatment on the substrate to form a reinforcing layer includes:
[0028] The substrate is surface-strengthened using physical vapor deposition or plasma-enhanced chemical vapor deposition. The surface-strengthening temperature is ≤400℃. The doping gas source includes carbon source gas and / or nitrogen source gas, which allows carbon atoms and / or nitrogen atoms to be doped into a portion of the substrate to form a reinforcing layer. The thickness of the reinforcing layer is 10μm to 30μm.
[0029] The reinforcing layer is polished to a thickness of 1 μm to 5 μm, so that the surface roughness Ra of the reinforcing layer is less than 1 micrometer.
[0030] In the above scheme, polishing the reinforcing layer removes loose carbon and surface carbon solid solution compounds from its surface, making the reinforcing layer surface denser with a surface roughness of less than 1 micrometer. This facilitates the deposition of a denser and more compact composite wear-resistant layer in subsequent processes, improving the bonding strength between the composite wear-resistant layer and the substrate. In some embodiments, the method further includes:
[0031] Plasma bombardment is performed on the polished substrate surface under inert gas protection to further remove impurities from the substrate surface.
[0032] In some embodiments, the fabrication steps of the connecting layer and the transition layer include:
[0033] Under inert gas protection, a magnetron sputtering target is activated on the surface of the reinforcing layer of the substrate. The target includes at least one of titanium target, zirconium target, niobium target, chromium target and silicon target to form a bonding layer.
[0034] A carbon source gas is introduced and deposited on the surface of the connecting layer. The flow rate of the carbon source gas is gradually increased from 30 Sccm to 300 Sccm to form a transition layer. The mass percentage of carbon atoms in the transition layer gradually increases from the side closer to the connecting layer to the side closer to the TaC film.
[0035] As the flow rate of carbon source gas gradually increases during the deposition of the transition layer, the proportion of carbon atoms in the region of the transition layer far from the connecting layer increases, which means the composition of carbides is improved, and the transition layer exhibits a state of gradually increasing hardness.
[0036] In some embodiments, the fabrication steps of the connecting layer and the transition layer include:
[0037] Under inert gas protection, silicon source gas is introduced and deposited on the surface of the reinforcing layer of the substrate to form a bonding layer, wherein the bonding layer is a silicon layer;
[0038] A carbon source gas is introduced and deposited on the surface of the silicon layer. The flow rate of the carbon source gas is gradually increased from 30 Sccm to 300 Sccm to form a transition layer. The mass percentage of carbon atoms in the transition layer gradually increases from the side closer to the silicon layer to the side closer to the TaC film.
[0039] In some embodiments, the preparation steps of the TaC film layer include:
[0040] The graphite target is deposited onto the surface of the transition layer by means of filtered arc ion plating or arc ion plating, with a deposition temperature ≤200℃, to form a TaC film.
[0041] Thirdly, this application provides a wear-resistant structural component, which is formed using the aforementioned composite material.
[0042] The wear-resistant structural component of this application is prepared using the composite material of the first aspect of this application. Since the composite material of this application has high strength and high wear resistance, the wear-resistant structural component of this application also has high strength and high wear resistance.
[0043] Fourthly, this application provides a rotating shaft including the aforementioned wear-resistant structural component. The wear-resistant structural component of this application is made of the aforementioned composite material. Using the wear-resistant structural component in the rotating shaft can improve the wear resistance of the shaft, thereby increasing its service life and consequently extending the service life of the electronic device.
[0044] Fifthly, this application provides a foldable screen, including the aforementioned hinge. The folding portion of the foldable screen needs to withstand numerous folds; by improving the wear resistance of the hinge, the lifespan of the foldable screen is also extended.
[0045] Sixthly, this application provides an electronic device including the aforementioned wear-resistant structural component. The electronic device includes, but is not limited to, foldable phones, foldable computers, etc. Attached Figure Description
[0046] Figure 1 is a schematic diagram of the structure of the composite material in the embodiment provided in this application.
[0047] Figure 2 is a schematic diagram of the structure of the composite material according to another embodiment of this application.
[0048] Figure 3 is a schematic diagram of the wear-resistant structural component provided in this application. Detailed Implementation
[0049] The technical solutions provided in this application will be further described below with reference to specific embodiments and comparative examples, but this application is not limited to the following embodiments.
[0050] To better understand the technical solution of this application, the embodiments of this application are described in detail below.
[0051] It should be understood that the described embodiments are merely some, not all, of the embodiments in this application. All other embodiments obtained by those skilled in the art based on the embodiments in this application without inventive effort are within the scope of protection of this application.
[0052] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first" or "second" may explicitly or implicitly include one or more of that feature.
[0053] References to "one embodiment" or "some embodiments" as described in this specification mean that one or more embodiments of this application include a specific feature, structure, or characteristic described in connection with that embodiment. Therefore, the phrases "in one embodiment," "in some embodiments," "in other embodiments," "in still other embodiments," etc., appearing in different parts of this specification do not necessarily refer to the same embodiment, but rather mean "one or more, but not all, embodiments," unless otherwise specifically emphasized. The terms "comprising," "including," "having," and variations thereof mean "including but not limited to," unless otherwise specifically emphasized.
[0054] Metal Injection Molding (MIM) is a manufacturing method in which a plasticized mixture of metal powder and binder is injected into a mold to form a preform, and then debinded and sintered to densify the part to obtain the desired shape. MIM can be used to manufacture various small, precision structural parts. Components on the hinge of foldable mobile phones are generally manufactured using MIM.
[0055] To achieve a 180-degree folding motion in the open / closed state, the hinge of a foldable phone primarily uses MIM 17-4 or MIM 420 materials, which typically have a hardness between 350HV and 480HV. Since a damping mechanism is necessary for the hinge to open and close, providing the necessary damping force, this mechanism generates friction. Due to the insufficient wear resistance of current hinge component materials, these components wear down over time, causing structural changes. After prolonged use, the hinge's damping force decreases, resulting in a poorer folding feel and, in severe cases, damage to the phone's opening and closing function, ultimately impacting the user experience.
[0056] In a first aspect, this application provides a composite material. FIG1 is a schematic diagram of the structure of a composite material according to an embodiment of this application. As shown in FIG1, the composite material 1 includes a substrate 10 and a composite wear-resistant layer 20 disposed on the surface of the substrate 10. The portion of the substrate near the composite wear-resistant layer includes a reinforcing layer 11. The reinforcing layer 11 includes at least one of a carburized layer, a nitrided layer and a carbonitrided layer.
[0057] The composite wear-resistant layer 20 includes a connecting layer 21, a transition layer 22, and a TaC film layer 23 sequentially stacked on the surface of the substrate; wherein...
[0058] The connecting layer 21 includes at least one of a metal layer and a single silicon layer; the transition layer 22 is located between the connecting layer and the TaC film layer, and the material of the transition layer 22 includes at least one of a metal-metal carbide composite and a silicon-silicon carbide composite.
[0059] The total thickness of the composite wear-resistant layer 20 is greater than or equal to 1 μm, and the Vickers hardness is greater than or equal to 3000 HV.
[0060] The composite material provided in this application has a reinforcing layer near the composite wear-resistant layer. Because the reinforcing layer is doped with nitrogen and / or carbon, the substrate's resistance to plastic deformation is enhanced, improving its strength (yield strength and tensile strength) and hardness. At least one composite wear-resistant layer is formed on the surface of the reinforcing layer. This composite wear-resistant layer includes a connecting layer, a transition layer, and a TaC film layer stacked sequentially. The connecting layer enhances the bonding strength between the composite wear-resistant layer and the substrate. The transition layer is made of at least one of a metal-metal carbide composite or a silicon-silicon carbide composite. The transition layer is relatively softer than the TaC film layer. By placing the transition layer between the connecting layer and the TaC film layer, it acts as a buffer. The transition layer has higher hardness closer to the TaC film layer, reaching its maximum hardness at the TaC film layer. The TaC film layer is supported by the transition layer, which also enhances the bonding strength between the TaC film layer and the connecting layer and the substrate. Furthermore, the transition layer ensures that the surface hardness of the entire composite wear-resistant layer reaches the desired range. Wear-resistant structural components made using this composite material, such as the hinge components of folding mobile phones, can achieve excellent yield strength, tensile strength, and wear resistance, thereby improving the service life of wear-resistant structural components.
[0061] In some embodiments, the substrate 10 is formed by a MIM (Metal Injection Molding) process. The substrate 10 can be a cam structure, gear structure, spherical structure, or other desired shape structure, without limitation. It should be noted that MIM is a powder metallurgy forming technology that involves injecting a mixture of metal particles and binder into a mold to form a preform, and then completely removing the binder and densifying the preform during subsequent sintering. Before sintering, most of the organic binder in the preform needs to be removed through methods such as catalysis, heating, and dissolution.
[0062] The substrate 10 is a high-strength substrate with a yield strength greater than or equal to 1500 MPa, more preferably greater than or equal to 1800 MPa. The substrate's hardness is generally between 500 HV and 650 HV, and its elongation after fracture can be ≥5% to provide a substrate with high strength and high toughness. For example, the substrate material can be selected from Fe-Co-Cr-Ni-Mo series high-strength steel capable of MIM forming.
[0063] In some embodiments, the composition of the substrate, by weight percentage, includes 18.01% to 21% Co, 16.01% to 19% Ni, 10.01% to 13% Mo, 0% to 2% Ti, 0.05% to 1% Nb, 0.001% to 0.1% C, trace impurity elements totaling no more than 1%, and the balance Fe.
[0064] Trace impurity elements include elements such as Si, Mn, Cr, Al, Y, V, and rare earth elements, with a total weight content not exceeding 1%. Since the content of these trace impurity elements is small, they are unlikely to have a fundamental effect on improving the strength of the material. Therefore, all of these elements other than the main element are collectively referred to as trace impurity elements.
[0065] In some embodiments, the composition of the substrate, by weight percentage, includes: 6-8% Ni, 7-11% Co, 6.51-8.5% Mo, 9.1-12% Cr, Al≤0.5%, C≤0.1%, Nb≤1%, Si≤0.5%, Mn≤0.5%, and the balance Fe.
[0066] Since the hardness of the substrate itself is generally low, it is easy to cause severe wear during the friction between the substrate structure and other structural components. In this application, a substrate 10 containing a reinforcing layer 11 is obtained by performing surface strengthening treatment on at least a portion of the surface of the substrate.
[0067] In some embodiments, the reinforcing layer 11 includes at least one of a carburized layer, a nitrided layer, and a carbonitriding layer. In the specific preparation process, physical vapor deposition or plasma-enhanced chemical vapor deposition can be used to strengthen the surface of the substrate, and the doping gas source includes carbon source gas and / or nitrogen source gas.
[0068] The presence of the reinforcing layer 11 can improve the connection strength between the substrate 10 and the composite wear-resistant layer 20.
[0069] In some embodiments, the thickness of the reinforcing layer 11 is 5μm to 30μm, specifically 5μm, 7μm, 8μm, 10μm, 12μm, 15μm, 18μm, 20μm, 25μm, or 30μm, etc., or other values within the above range, which are not limited here. Controlling the thickness of the reinforcing layer within the above range is beneficial to enhancing the overall hardness of the entire substrate, thereby achieving the surface hardness of the substrate 10, providing a strong foundation for the composite wear-resistant layer, resulting in better wear resistance and more stable bonding of the composite wear-resistant layer. When the thickness of the reinforcing layer is less than 5μm, it will lead to a decrease in the overall wear resistance level.
[0070] In some embodiments, the Vickers hardness of the reinforcing layer 11 is 900 HV to 1200 HV, specifically 900 HV, 950 HV, 1000 HV, 1050 HV, 1100 HV, 1150 HV, 1180 HV, or 1200 HV, etc., or other values within the above range, which are not limited here. Understandably, the initial Vickers hardness of the substrate is generally 500 HV to 650 HV, and the Vickers hardness of the substrate can be significantly improved through surface strengthening treatment.
[0071] In some embodiments, the doping concentration of carbon and / or nitrogen atoms in the reinforcing layer 11 is 5% to 50%, specifically 5%, 8%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, or 50%, etc., and other values within the above range are also possible and are not limited here. Understandably, when the concentration of doped atoms in the reinforcing layer 11 is within the above range, an appropriate amount of doped atoms can penetrate into the metal lattice, causing lattice distortion, refining the metal grains, increasing the resistance to dislocation movement, and enhancing the metal's resistance to plastic deformation, thereby improving the strength (yield strength and tensile strength) and hardness of the substrate, and improving the overall wear resistance of the composite material. If the concentration of doped atoms is too high, it may reduce the toughness of the substrate. Preferably, the doping concentration of carbon and / or nitrogen atoms in the reinforcing layer 11 is 10% to 40%.
[0072] In some embodiments, the composite wear-resistant layer 20 is disposed on the surface of the substrate 10, and it can be a single-layer structure or a multi-layer structure of multiple composite wear-resistant layers.
[0073] Specifically, the composite wear-resistant layer 20 includes a connecting layer 21, a transition layer 22, and a TaC film layer 23 sequentially stacked on the surface of the substrate 10.
[0074] The connecting layer 21 includes at least one of a metal layer and a elemental silicon layer. The metal element in the metal layer can be at least one of Ti, Cr, Zr, and Nb. Exemplarily, the metal layer can be a titanium layer, a laminated structure of titanium and chromium layers, or a spliced structure of titanium and chromium layers; no limitation is made here. These metals all possess high strength (yield strength and tensile strength), which can enhance the overall structural strength of the composite material. Furthermore, they have relatively low density and good integration with the substrate, which is beneficial for achieving lightweight composite materials and reducing the weight of wear-resistant structural components.
[0075] In some embodiments, the elemental silicon layer may be a crystalline silicon layer and / or an amorphous silicon layer, which is not limited here. The elemental silicon layer is a reinforcing layer connected to the substrate 10. In certain specific scenarios, the entire film layer needs to be an insulating layer. As a semiconductor, the elemental silicon layer has extremely poor conductivity, which can achieve insulation between the substrate and the composite wear-resistant layer.
[0076] In some embodiments, the thickness of the connecting layer 21 is 100nm to 2000nm, specifically 100nm, 200nm, 500nm, 800nm, 1000nm, 1200nm, 1500nm, 1800nm, or 2000nm, etc., or other values within the above range, which are not limited here. Controlling the thickness of the connecting layer 21 within the above range is beneficial to improving the bonding strength between the composite wear-resistant layer 20 and the substrate 10, and is also beneficial to controlling the total thickness of the composite material.
[0077] In some embodiments, the transition layer 22 is located between the connecting layer 21 and the TaC film layer 23, and the material of the transition layer 22 includes a composite of metal and metal carbide. Specifically, the material of the transition layer 22 may be at least one composite selected from titanium and titanium carbide, zirconium and zirconium carbide, chromium and chromium carbide, niobium and niobium carbide, and silicon and silicon carbide.
[0078] When the connecting layer includes at least one of titanium layer, zirconium layer, chromium layer, and niobium layer, the material of the transition layer includes at least one composite of titanium and titanium carbide, zirconium and zirconium carbide, chromium and chromium carbide, and niobium and niobium carbide.
[0079] When the connecting layer comprises a single-element silicon layer, the transition layer is made of a composite material of silicon and silicon carbide. The elements in the connecting layer are consistent with the non-carbon elements in the transition layer.
[0080] In some preferred embodiments, the metal element in the transition layer 22 is the same type as the metal element in the connecting layer. Using the same type of metal element is beneficial to improving the compatibility between the transition layer and the connecting layer, which can further improve the bonding strength between the transition layer and the connecting layer and enhance the overall structural strength of the composite wear-resistant layer 20.
[0081] When multiple composite wear-resistant layers are stacked, any one of the composite wear-resistant layers can use elemental silicon as a connecting layer, thereby achieving insulation performance between the composite wear-resistant layer and the substrate.
[0082] In some embodiments, the mass percentage of carbon atoms in the transition layer 22 gradually increases from the side closer to the connecting layer 21 to the side closer to the TaC film 23. That is, the mass percentage of metal carbides in the region of the transition layer 22 closer to the connecting layer 21 is relatively small, and the transition layer 22 in this region is softer than the TaC film 23, which helps to improve the adhesion between the composite wear-resistant layer 20 and the substrate 10, and can reduce the internal stress of the deposited TaC film 23. As the transition layer 22 approaches the TaC film 23, the mass percentage of carbon atoms (metal carbides) in this region gradually increases, and the hardness of the transition layer 22 in this region gradually approaches that of the TaC film 23.
[0083] In some embodiments, the thickness of the transition layer 22 is 100nm to 2000nm, specifically 100nm, 200nm, 500nm, 800nm, 1000nm, 1200nm, 1500nm, 1800nm or 2000nm, etc., and of course, other values within the above range are also possible, which are not limited here.
[0084] In some embodiments, the TaC (Tetrahedral Amorphous Carbon) film 23 is a hydrogen-free diamond-like film with a diamond SP3 bond content of over 85%, possessing advantages such as extremely high hardness, extremely low coefficient of friction, high elastic modulus, wide light transmittance range, and good chemical inertness. Its physicochemical properties are extremely similar to those of diamond.
[0085] In some embodiments, the surface hardness of the TaC film layer 23 is ≥5000HV. Since the surface of the composite material is the TaC film layer 23, its surface hardness is high. The wear-resistant structural parts made of the composite material of this application can have high surface hardness, which can reduce wear loss and improve the wear resistance of the structural parts, and can achieve more than 200,000 wear cycles.
[0086] In some embodiments, the thickness of the TaC film 23 is 0.25 μm to 20 μm, specifically 0.25 μm, 0.3 μm, 0.5 μm, 0.8 μm, 1 μm, 2 μm, 4 μm, 5 μm, 8 μm, 10 μm, 15 μm, 18 μm, or 20 μm, etc., or other values within the above range, which are not limited here. Controlling the TaC film thickness within the above range can effectively improve the wear resistance of the composite material, and its thickness can be adjusted by the vapor deposition process. When the TaC film thickness is too small, the wear resistance of the composite material decreases, the service life of the wear-resistant structural parts is shortened, and phenomena such as substrate cracking are prone to occur. When the TaC film thickness is too large, the preparation cost of the composite material increases, and the overall thickness of the composite material also increases significantly, which is not conducive to the lightweighting of wear-resistant structural parts.
[0087] In some embodiments, the total thickness of the composite wear-resistant layer is greater than or equal to 1 μm, specifically 1 μm, 2 μm, 4 μm, 8 μm, 10 μm, 20 μm, 30 μm, 50 μm, or 67 μm, etc., and of course, other values within the above range are also possible, which are not limited here. Preferably, the total thickness of the composite wear-resistant layer is 10 μm to 50 μm.
[0088] In some embodiments, the Vickers hardness of the composite wear-resistant layer is greater than or equal to 3000 HV. The synergistic effect of the transition layer and the TaC film layer enables the Vickers hardness of the composite wear-resistant layer to reach over 3000 HV. Experiments have shown that cam structures made from substrates treated only with carburization exhibit fracture during repeated folding. This is because the increased brittleness and decreased hardness of the substrate make it difficult to withstand repeated opening and closing tests.
[0089] The composite material used in this application to make structural components such as rotating cams and gears has high wear resistance, and the wear amount can still be controlled within a small range even after more than 200,000 cycles.
[0090] The structure and composition of the composite material have been explained above. The specific preparation method will be further explained in detail below.
[0091] This application provides a method for preparing the above-mentioned composite material.
[0092] S100, the substrate is subjected to surface strengthening treatment to form a reinforcing layer, the reinforcing layer including at least one of a carburizing layer, a nitriding layer and a carbonitriding layer;
[0093] S200, at least one composite wear-resistant layer is formed on the surface of the reinforcing layer, the composite wear-resistant layer includes a connecting layer, a transition layer and a TaC film layer, and the total thickness of the composite wear-resistant layer is greater than or equal to 1 μm.
[0094] In one embodiment of this application, prior to step S100, the method further includes preparing a substrate using a metal injection molding method.
[0095] The ingredients are prepared according to the weight ratio of the components. As an example, the components of the substrate are selected based on the weight percentage of the substrate, including 19% to 21% Co, 6% to 10% Ni, 6% to 12% Mo, 0.3% to 2% Ti and the balance Fe. The particle size D50 of each metal powder can be 3 to 18 μm. The substrate powder can be obtained after mixing the raw materials.
[0096] The binder composition may consist of polyoxymethylene (POM), ethylene-vinyl acetate (EVA), polyethylene (PE), paraffin wax (PW), and stearic acid (SA). As an example, the weight ratio of these binder components may be, for example, POM:EVA:PE:PW:SA = 89:1:5:2:1. It is understood that the above weight ratio is merely an example, and the specific composition and proportions of the binder may be adjusted according to the specific wear-resistant powder. No specific limitations are made here regarding the specific composition and proportions of the binder.
[0097] The binder is mixed with the substrate powder and then added to the hopper of an injection molding machine for injection molding to obtain a substrate preform.
[0098] The substrate can be obtained by further catalytic degreasing, sintering, and heat treatment of the substrate green.
[0099] S100, the substrate is subjected to surface strengthening treatment to form a reinforcing layer, the reinforcing layer including at least one of a carburizing layer, a nitriding layer and a carbonitriding layer.
[0100] In some embodiments, step S100 includes: performing surface strengthening treatment on the substrate using physical vapor deposition or plasma-enhanced chemical vapor deposition, wherein the surface strengthening treatment temperature is ≤400°C, and the doping gas source includes carbon source gas and / or nitrogen source gas, so that carbon atoms and / or nitrogen atoms are doped into a portion of the substrate to form a strengthening layer, wherein the thickness of the strengthening layer is 10μm to 30μm.
[0101] In some embodiments, the doping gas source is a nitrogen source gas, and the surface strengthening treatment temperature is ≤400℃, specifically 400℃, 350℃, 300℃, 280℃, 260℃, 250℃, or 200℃, etc., or other values within the above range, which are not limited here. In actual processing, the temperature inside the vapor deposition furnace can be controlled to ≤200℃, which is lower than the conventional nitriding temperature (e.g., 500℃~900℃).
[0102] Understandably, controlling the temperature below 400℃ during surface strengthening treatment facilitates nitrogen atom doping into the substrate, causing at least a portion of the substrate to transform into substrate nitrides. Compared to conventional high-temperature silicon nitriding, this low-temperature nitriding process reduces substrate fracture and ensures the structural strength of the substrate. Experiments have shown that high-temperature carburizing processes lead to a decrease in the hardness and strength of the substrate, making it difficult to withstand repeated cyclic opening and closing tests; some structural components treated with high-temperature carburizing directly fractured.
[0103] In some embodiments, the doping gas source is a carbon source gas, and the surface strengthening treatment temperature is ≤450℃, specifically 450℃, 430℃, 400℃, 350℃, 300℃, 280℃, 260℃, 250℃ or 200℃, etc., or other values within the above range, which are not limited here.
[0104] In some embodiments, physical vapor deposition processes include evaporation deposition, magnetron sputtering, ion plating, etc., wherein ion plating can be exemplary, such as hollow cathode ion plating, hot cathode ion plating, arc ion plating, filtered arc ion plating, reactive ion plating, radio frequency ion plating, DC discharge ion plating, etc. By depositing dopant atoms or molecules onto the surface of a substrate through physical vapor deposition processes, the Vickers hardness of the substrate can be enhanced.
[0105] In some embodiments, step S100 further includes polishing the reinforcing layer to a thickness of 1 μm to 5 μm, such that the surface roughness Ra of the reinforcing layer is less than 1 micrometer.
[0106] Specifically, polishing can be at least one of sandblasting and polishing, which can remove the loose structure on the surface of the substrate. The polishing thickness can be, for example, 1μm, 2μm, 3μm, 3.5μm, 4μm or 5μm, etc., and can be adjusted according to actual needs, which is not limited here.
[0107] In some embodiments, after step S100 and before S200, the method further includes:
[0108] The polished substrate surface is subjected to plasma bombardment under inert gas protection to further remove impurities. The treated substrate retains only a high-strength, hard layer, thus ensuring the overall strength of the substrate.
[0109] S200, at least one composite wear-resistant layer is formed on the surface of the reinforcing layer, the composite wear-resistant layer includes a connecting layer, a transition layer and a TaC film layer, and the total thickness of the composite wear-resistant layer is greater than or equal to 1 μm.
[0110] In some embodiments, the fabrication steps of the connecting layer and the transition layer include:
[0111] Under inert gas protection, a magnetron sputtering target is activated on the surface of the reinforcing layer of the substrate. The target includes at least one of titanium target, zirconium target, niobium target, chromium target and silicon target to form a bonding layer.
[0112] A carbon source gas is introduced and deposited on the surface of the connecting layer. The flow rate of the carbon source gas is gradually increased from 30 sccm to 300 sccm to form a transition layer. The mass percentage of carbon atoms in the transition layer gradually increases from the side closer to the connecting layer to the side closer to the TaC film.
[0113] Correspondingly, the mass content of metal atoms or silicon atoms in the transition layer is higher closer to the location of the connecting layer.
[0114] In some specific embodiments, the flow rate of the carbon source gas can be 30 sccm, 50 sccm, 80 sccm, 100 sccm, 120 sccm, 150 sccm, 180 sccm, 200 sccm, 250 sccm, or 300 sccm, or other values within the above range, which are not limited here. As the flow rate of the carbon source gas gradually increases during the deposition of the transition layer, the proportion of carbon atoms in the region of the transition layer far from the connecting layer increases, causing the transition layer to exhibit a transition from soft to hard. However, this "softness" refers only to the hardness relative to the TaC film; it is actually a film with hardness.
[0115] In some embodiments, the fabrication steps of the connecting layer and the transition layer include:
[0116] Under inert gas protection, silicon source gas is introduced and deposited on the surface of the reinforcing layer of the substrate to form a bonding layer, wherein the bonding layer is a silicon layer;
[0117] A carbon source gas is introduced and deposited on the surface of the silicon layer. The flow rate of the carbon source gas is gradually increased from 30 sccm to 300 sccm to form a transition layer. The mass percentage of carbon atoms in the transition layer gradually increases from the side closer to the silicon layer to the side closer to the TaC film.
[0118] In the above scheme, the transition layer comprises a composite of silicon and silicon carbide, and the mass percentage of carbon atoms in the transition layer gradually increases from the side closer to the silicon layer to the side closer to the TaC film layer, meaning the silicon carbide component gradually increases. Silicon carbide, understandably, possesses extremely high hardness, with a Mohs hardness of approximately 9.5, and exhibits good thermal stability and high-temperature strength. Because the connecting layer is a silicon layer, the semiconductor properties of silicon enable the wear-resistant structural components to be used in insulating applications.
[0119] In some embodiments, the preparation steps of the TaC film layer include:
[0120] The graphite target is deposited onto the surface of the transition layer by means of filtered arc ion plating or arc ion plating, with a deposition temperature ≤200℃, to form a TaC film.
[0121] This application controls the deposition temperature to a lower range, which is beneficial for the formation of a dense and uniform TaC film on the surface of the composite wear-resistant layer, thereby improving the wear resistance of the composite wear-resistant layer.
[0122] The above are merely preferred embodiments of this application and are not intended to limit this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of protection of this application.
[0123] This application also provides a wear-resistant structural component, which is prepared from the aforementioned composite material. Its shape is not strictly limited and can be set according to the specific shape and structure of the part formed by the MIM process. Because the wear-resistant structural component provided in this application possesses excellent wear resistance and hardness, enhanced resistance to mechanical impact, and improved wear resistance, especially during bending, it is particularly suitable as a component for precision equipment shafts, such as cams, gears, track grooves, precision equipment brackets, and camera decorative parts.
[0124] For example, the hinge of a folding phone has very high requirements for wear resistance. During tens of thousands to hundreds of thousands of opening and closing cycles, the surface is easily worn, the contact area size decreases, and gaps appear between the parts. This results in a reduction in the opening and closing force of the folding phone during the opening and closing process. The wear-resistant structural component 200 made of the composite material of this application, such as the cam of the hinge, as shown in Figure 3, can significantly improve the wear resistance performance.
[0125] Specifically, the cross-section of wear-resistant structural components can be arc-shaped, cylindrical, rectangular, square, rhomboid, etc., but is not limited to these.
[0126] In some embodiments, the wear-resistant structural components are electronic device parts or mechanical device parts. Using the aforementioned wear-resistant structural components as electronic device or mechanical device parts can enhance the hardness and wear resistance of these parts, thus improving the wear resistance of precision electronic and mechanical devices. Examples of electronic devices include, but are not limited to, mobile phones, tablets, computers, POS machines, and wearable electronic products. The types of mechanical devices are not limited, including mechanical devices from various fields, such as tractors, seeders, harvesters, pumps, fans, valves, gas compressors, electromechanical equipment, transformers, electric motors, high and low voltage switches, wires and cables, batteries, welding machines, automobiles, instruments, etc. Particular emphasis is placed on mechanical devices with precision components, such as automotive structural components like connecting rods. In some embodiments, the wear-resistant structural components are camera trim pieces, cams, shaft supports, connecting rods, track grooves, or gears. In this case, integrally molded components such as camera trim pieces, cams, shaft supports, connecting rods, track grooves, or gears can simultaneously possess high toughness and high hardness, thereby improving the wear resistance and drop reliability of the components.
[0127] This application also provides a foldable screen, which includes the above-mentioned wear-resistant structural components, thereby improving the stability of the foldable screen during folding.
[0128] This application also provides an electronic device. The electronic device includes the wear-resistant structural component provided in the above-described embodiment of this application. Because some components of the electronic device use the aforementioned wear-resistant structural component, and the wear-resistant structural component has excellent hardness and wear resistance, the hardness and toughness of the electronic device, especially the corresponding components, are improved, and the wear resistance and drop reliability of the corresponding components are also correspondingly enhanced.
[0129] In some implementations, the electronic device is a computer, mobile phone, tablet, wearable product, or vehicle.
[0130] The present application is further illustrated below with reference to embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the present application.
[0131] Example 1
[0132] (1) Prepare the rotating shaft cam structure using MIM steel with a yield strength ≥1800MPa as raw material and form MIM ultra-high strength steel cam parts using MIM metal injection molding process; the raw materials are prepared according to the weight ratio of the components, and the raw materials include the following components: 18.01%~21% Co, 16.01%~19% Ni, 10.01%~13% Mo, 0%~2% Ti, 0.05%~1% Nb, 0.001%~0.1% C and the balance Fe and trace impurity elements. The total content of impurities including Si, Mn, Cr, Al, Y, V, rare earth elements does not exceed 1%.
[0133] (2) Place the cam structure into a plasma vacuum furnace, introduce C2H2 gas, heat the furnace cavity temperature to 410°C, and set the DC voltage to 600V to form glow discharge in the furnace cavity. Under these conditions, perform surface strengthening treatment for 16 hours, and then cool to room temperature to form a carburized layer with a thickness of 18 micrometers. The Vickers hardness of the carburized layer gradually increases from the inside of the substrate to the surface, and can be increased from 350HV to 1100HV.
[0134] (3) The carburized layer on the substrate surface is modified. During the carburizing process, floating carbon and loose surface carbon solid solution are easily formed on the substrate surface. These can be removed by polishing or sandblasting. The removal depth is 3 micrometers. The surface of the cam structure after polishing is dense and the surface roughness is better. The surface roughness Ra is less than 1 micrometer. Then, the cam structure is placed in a magnetic filter multi-arc ion plating PVD furnace. Argon gas with a negative bias of 600V is used to bombard the surface of the cam structure for 30 minutes to remove impurities and loose structure on the surface, and the substrate after surface modification is obtained.
[0135] (4) Open the titanium target in the magnetically filtered multi-arc ion plating PVD furnace, perform pure target deposition, control the negative bias voltage to 150V, and deposit a titanium layer (connecting layer) with a thickness of 300nm.
[0136] (5) Introduce acetylene and gradually increase the flow rate of acetylene from 30 sccm to 300 sccm (sccm: standard milliliters / minute) to deposit and form a transition layer. The transition layer gradually hardens from the surface of the titanium layer. By setting the transition layer, it helps to improve the bonding force between the transition layer and the substrate and reduce the internal stress of the substrate.
[0137] (6) Gradually shut off the acetylene gas, and at the same time shut off the titanium target and turn on the pure graphite target. Increase the negative bias voltage to 600V to enter the deposition of TaC film (tetrahedral amorphous carbon film). The deposition thickness is 1.1 micrometers to obtain wear-resistant structural parts.
[0138] The wear-resistant structural component prepared according to the embodiments of this application includes a substrate and a composite wear-resistant layer disposed on the surface of the substrate. The composite wear-resistant layer includes a titanium layer, a transition layer formed by a composite of titanium and titanium carbide, and a TaC layer. The total thickness of the composite wear-resistant layer is 1.7 μm, wherein the thickness of the TaC layer is 1.1 μm.
[0139] Example 2
[0140] Unlike Example 1:
[0141] Repeat steps (4), (5) and (6) three times to form a three-layer composite wear-resistant layer with a total thickness of 5.1 μm.
[0142] Example 3
[0143] Unlike Example 1:
[0144] Repeat steps (4), (5) and (6) 10 times to form a multi-layer composite wear-resistant layer with a total thickness of 17 μm.
[0145] Example 4
[0146] Unlike Example 1:
[0147] Repeat steps (4), (5) and (6) 25 times to form a multi-layer composite wear-resistant layer with a total thickness of 42.5 μm.
[0148] Example 5
[0149] Unlike Example 1:
[0150] The target material in step (4) is a zirconium target, and a zirconium layer (connecting layer) with a thickness of 500 nm is deposited.
[0151] Example 6
[0152] Unlike Example 1:
[0153] The target material in step (4) is a chromium target, and a chromium layer (connecting layer) with a thickness of 800 nm is deposited.
[0154] Example 7
[0155] Unlike Example 1:
[0156] The target material in step (4) is a niobium target, and a niobium layer (connecting layer) with a thickness of 2000 nm is deposited.
[0157] Example 8
[0158] (1) Prepare the rotating cam structure using MIM steel with a yield strength ≥1500MPa as raw material and form MIM ultra-high strength steel cam parts by using MIM metal injection molding process; the raw materials are prepared according to the weight ratio of the components, and the raw materials include the following components: Ni 6-8%, Co 7-11%, Mo 6.51-8.5%, Cr 9.1-12%, Al≤0.5%, C≤0.1%, Nb≤1%, Si≤0.5%, Mn≤0.5% and the balance Fe.
[0159] (2) Place the cam structure into a plasma vacuum furnace, introduce nitrogen gas, heat the furnace chamber to 180°C, and set the DC voltage to 600V to form glow discharge and plasma in the furnace chamber. Under these conditions, perform surface strengthening treatment for 10 hours, and then cool to room temperature to form a nitriding layer with a thickness of 14 micrometers. The Vickers hardness of the nitriding layer gradually increases from the inside of the substrate to the surface, and can be increased from 200HV to 500HV to 1100HV. (3) The nitriding layer on the substrate surface is modified. During the nitriding process, floating nitrogen and loose surface nitrogen solid solution are easily formed on the substrate surface. These can be removed by polishing or sandblasting. The removal depth is 0.5 to 2 micrometers. The surface of the cam structure after polishing is dense and the surface roughness is better, with the surface roughness Ra less than 1 micrometer. Then, the cam structure is placed in a magnetic filter multi-arc ion plating PVD furnace. Argon gas with a negative bias voltage of 600V is used to bombard the surface of the cam structure for 30 minutes to further remove surface impurities and loose structure, and obtain the substrate after surface modification.
[0160] (4) Open the chromium target in the magnetic filter multi-arc ion plating PVD furnace, perform pure target deposition, control the negative bias voltage to 200V, and deposit a chromium layer (connecting layer) with a thickness of 400nm.
[0161] (5) Introduce acetylene and gradually increase the flow rate of acetylene from 30 sccm to 300 sccm (sccm: standard milliliters / minute) to deposit and form a transition layer. The transition layer gradually hardens from the surface of the chromium layer. By setting the transition layer, it helps to improve the bonding force between the transition layer and the substrate and reduce the internal stress of the substrate.
[0162] (6) Gradually shut off the acetylene gas, while simultaneously shutting off the chromium target and turning on the pure graphite target. Increase the negative bias voltage to 800V to begin the deposition of the TaC film (tetrahedral amorphous carbon film). The deposition thickness is 1.25μm, resulting in a wear-resistant structural component.
[0163] The wear-resistant structural component prepared according to the embodiments of this application includes a substrate and a composite wear-resistant layer disposed on the surface of the substrate. The portion of the substrate near the composite wear-resistant layer is a nitrided layer. The composite wear-resistant layer includes a chromium layer, a transition layer formed by a composite of chromium and chromium carbide, and a TaC layer. The total thickness of the composite wear-resistant layer is 2.25 μm, of which the thickness of the TaC layer is 1.25 μm.
[0164] Example 9
[0165] The difference from Example 8 is:
[0166] Repeat steps (4), (5) and (6) twice to form a two-layer composite wear-resistant layer with a total thickness of 4.5 μm.
[0167] Example 10
[0168] The difference from Example 8 is:
[0169] Repeat steps (4), (5) and (6) 10 times to form a two-layer composite wear-resistant layer with a total thickness of 22.5 μm.
[0170] Example 11
[0171] The difference from Example 8 is:
[0172] Repeat steps (4), (5) and (6) 15 times to form a two-layer composite wear-resistant layer with a total thickness of 33.75 μm.
[0173] Example 12
[0174] The difference from Example 8 is:
[0175] Repeat steps (4), (5) and (6) 30 times to form a two-layer composite wear-resistant layer with a total thickness of 67.5 μm.
[0176] Example 13
[0177] Unlike Example 1:
[0178] (2) Place the cam structure into a plasma vacuum furnace and introduce nitrogen and C2H2 gas with a volume ratio of 1:1. Heat the furnace cavity to 200°C and DC voltage to 600V to form glow discharge and plasma in the furnace cavity. Under these conditions, perform surface strengthening treatment for 24 hours and then cool to room temperature to form a carbonitriding layer with a thickness of 30 micrometers. The Vickers hardness of the carbonitriding layer gradually increases from the inside of the substrate to the surface, and can be increased from 200HV to 500HV to 1100HV.
[0179] Example 14
[0180] Unlike Example 1:
[0181] (4) Place the damping structure into the plasma vacuum furnace, turn on the silicon target, and deposit a silicon layer (connection layer) with a thickness of 300nm.
[0182] (5) Introduce acetylene and gradually increase the flow rate of acetylene from 30 sccm to 300 sccm (sccm: standard milliliters / minute) to deposit and form a transition layer. The transition layer gradually hardens from the surface of the silicon layer. By setting the transition layer, it helps to improve the bonding force between the transition layer and the substrate and reduce the internal stress of the substrate.
[0183] (6) Gradually shut off the acetylene gas, turn on the pure graphite target, increase the negative bias voltage to 600V, and begin the deposition of the TaC film (tetrahedral amorphous carbon film) with a deposition thickness of 1.1 micrometers to obtain a wear-resistant structural component.
[0184] Example 15
[0185] Unlike Example 1:
[0186] Step (5) was skipped, and step (6) was performed directly.
[0187] Comparative Example 1
[0188] (1) Prepare round bar structural parts with a diameter of 3.22 mm. Use MIM steel with a yield strength ≥1800 MPa as raw material and use MIM metal injection molding process to form MIM ultra-high strength round bars. The raw materials are formulated according to the weight ratio of the components. The raw materials include the following components: Co 19-21%, Ni 6-10%, Mo 6-12%, Ti 0.3-2%, and the total content of other elements is not higher than 1%, with the balance being Fe.
[0189] (2) Place the round bar structure into a plasma vacuum furnace, introduce C2H2 gas, heat the furnace cavity temperature to 410℃, and set the DC voltage to 600V to form glow discharge in the furnace cavity. Under these conditions, perform surface strengthening treatment for 36 hours, and then cool to room temperature to form a carburized layer with a thickness of 15μm.
[0190] Comparative Example 2
[0191] (1) Prepare round bar structural parts with a diameter of 3.22 mm. Use MIM steel with a yield strength ≥1800 MPa as raw material and use MIM metal injection molding process to form MIM ultra-high strength round bars. The raw materials are formulated according to the weight ratio of the components. The raw materials include the following components: Co 19-21%, Ni 6-10%, Mo 6-12%, Ti 0.3-2%, and the total content of other elements is not higher than 1%, with the balance being Fe.
[0192] (2) Place the round bar structure into a plasma vacuum furnace, introduce C2H2 gas, heat the furnace cavity temperature to 410℃, and set the DC voltage to 600V to form glow discharge in the furnace cavity. Under these conditions, perform surface strengthening treatment for 36 hours, and then cool to room temperature to form a carburized layer with a thickness of 30μm.
[0193] Comparative Example 3
[0194] Unlike Example 1:
[0195] Steps (2) and (3) were not performed.
[0196] The specific physicochemical parameters of the composite material structural components obtained in the above embodiments and comparative examples are detailed in Table 1.
[0197] [Testing Method]
[0198] (1) The shafts were assembled using the cam structure components of each embodiment and comparative example. The shafts were tested for opening and closing. The number of samples corresponding to each embodiment and comparative example was 3, and the number of opening and closing cycles was 200,000. Then the maximum wear of the cam was tested. The test results are listed in Table 2.
[0199] (2) Vickers hardness tests were conducted on the cam structures of each embodiment and comparative example, and the test results are shown in Table 2.
[0200] Table 1. Process parameters for the examples and comparative examples.
[0201] Table 2 Performance test data of wear-resistant structural components
[0202] According to the test data of Examples 1 to 15, the examples use a substrate containing carburizing and / or nitriding treatment. At least one composite wear-resistant layer is formed on the surface of the reinforcing layer of the substrate. The Vickers hardness of the resulting composite material can reach more than 3000 HV. In addition, after repeated opening and closing 200,000 times, the wear amount of the wear-resistant structural parts made of the composite material is <20%.
[0203] According to the test data of Examples 1 to 4 and Examples 9 to 12, the surface Vickers hardness of the composite material increases with the increase of the number of composite wear-resistant layers.
[0204] According to the test data of Examples 5 to 7, the thickness of the connecting layer and transition layer of different materials has little impact on the performance of the composite material. The Vickers hardness of the composite material can fluctuate around 3300 HV, and the attenuation of the structural parts made of the composite material can be controlled at around 16%. It can withstand repeated opening and closing tests of 200,000 times without structural breakage.
[0205] According to the test data of Examples 1 and 15, no transition layer is formed between the connecting layer and the single TaC film layer in the composite wear-resistant layer of Example 15. Compared with Example 1, the wear of the wear-resistant structural component of Example 15 has increased. This is because the lack of a transition layer to buffer the friction pressure of the TaC layer makes it difficult to fully release the internal stress formed by TaC deposition, so the hardness of the composite wear-resistant layer has also decreased.
[0206] According to the test data of Example 1 and Comparative Examples 1 and 2, the wear-resistant structural parts without a composite wear-resistant layer on their surface significantly increased wear. Furthermore, the surface hardness of the wear-resistant structural parts treated only with carburizing was only 800-1100 HV, which is insufficient to meet current wear-resistant hardness requirements. The reinforcing layer was also relatively thin; tests showed severe wear after 5000 repeated opening and closing cycles, and the reinforcing layer was worn through after 200,000 repeated opening and closing cycles.
[0207] According to the test data of Example 2 and Comparative Example 3, since the matrix material was not subjected to infiltration and / or nitriding treatment, the strength of the matrix material decreased. Although the surface hardness of the wear-resistant structural parts could still be maintained at a high level, the wear of the wear-resistant structural parts also increased significantly after 200,000 repeated opening and closing cycles due to the decrease in the strength of the matrix material.
[0208] Although this application discloses preferred embodiments as described above, it is not intended to limit the claims. Any person skilled in the art can make several possible changes and modifications without departing from the concept of this application. Therefore, the scope of protection of this application should be determined by the scope defined in the claims of this application.
Claims
1. A composite material, characterized in that, It includes a substrate and a composite wear-resistant layer disposed on the surface of the substrate; the portion of the substrate near the composite wear-resistant layer includes a reinforcing layer, the reinforcing layer including at least one of a carburized layer, a nitrided layer and a carbonitrided layer; The composite wear-resistant layer comprises a connecting layer, a transition layer, and a TaC film layer sequentially stacked on the surface of the substrate; wherein... The connecting layer includes at least one of a metal layer and a single silicon layer; the transition layer is located between the connecting layer and the TaC film layer, and the material of the transition layer includes at least one of a metal-metal carbide composite and a silicon-silicon carbide composite. The total thickness of the composite wear-resistant layer is greater than or equal to 1 μm, and the Vickers hardness is greater than or equal to 3000 HV.
2. The composite material according to claim 1, characterized in that, The connecting layer includes at least one of a titanium layer, a zirconium layer, a chromium layer, and a niobium layer.
3. The composite material according to claim 2, characterized in that, The material of the transition layer includes at least one composite of titanium and titanium carbide, zirconium and zirconium carbide, chromium and chromium carbide, and niobium and niobium carbide; the metal element in the transition layer is of the same type as the metal element in the connecting layer.
4. The composite material according to claim 1, characterized in that, The connecting layer includes a single silicon layer, and the transition layer is made of a composite of silicon and silicon carbide.
5. The composite material according to any one of claims 1 to 4, characterized in that, The composite material satisfies at least one of the following characteristics: a) The thickness of the connecting layer is 100nm to 2000nm; b) The thickness of the reinforcing layer is 5μm to 30μm; c) The thickness of the transition layer is 100nm to 2000nm.
6. The composite material according to any one of claims 1 to 4, characterized in that, The thickness of the TaC film is 0.25 μm to 20 μm.
7. The composite material according to any one of claims 1 to 4, characterized in that, The composition of the substrate, by weight percentage, includes 18.01% to 21% Co, 16.01% to 19% Ni, 10.01% to 13% Mo, 0% to 2% Ti, 0.05% to 1% Nb, 0.001% to 0.1% C, trace impurity elements not exceeding 1% in total, and the balance Fe.
8. The composite material according to any one of claims 1 to 4, characterized in that, The yield strength of the substrate is ≥2000MPa.
9. The composite material according to any one of claims 1 to 4, characterized in that, The mass percentage of carbon atoms in the transition layer gradually increases from the side closer to the connecting layer to the side closer to the TaC film.
10. The composite material according to any one of claims 1 to 4, characterized in that, The composite material includes a substrate and multiple stacked composite wear-resistant layers, the total thickness of which is 10μm to 50μm.
11. A method for preparing a composite material according to any one of claims 1 to 10, characterized in that, Includes the following steps: A reinforcing layer is formed by performing a surface strengthening treatment on the substrate, the reinforcing layer comprising at least one of a carburizing layer, a nitriding layer, and a carbonitriding layer; At least one composite wear-resistant layer is formed on the surface of the reinforcing layer. The composite wear-resistant layer includes a connecting layer, a transition layer, and a TaC film layer. The total thickness of the composite wear-resistant layer is greater than or equal to 10 μm.
12. The method for preparing the composite material according to claim 11, characterized in that, The step of performing surface strengthening treatment on the substrate to form a reinforcing layer includes: The substrate is surface-strengthened using physical vapor deposition or plasma-enhanced chemical vapor deposition. The surface-strengthening temperature is ≤400℃. The doping gas source includes carbon source gas and / or nitrogen source gas, which allows carbon atoms and / or nitrogen atoms to be doped into a portion of the substrate to form a reinforcing layer. The thickness of the reinforcing layer is 10μm to 30μm. The reinforcing layer is polished to a thickness of 1 μm to 5 μm, so that the surface roughness Ra of the reinforcing layer is less than 1 micrometer.
13. The method for preparing the composite material according to claim 12, characterized in that, The method further includes: Plasma bombardment is performed on the polished substrate surface under inert gas protection to further remove impurities from the substrate surface.
14. The method for preparing the composite material according to claim 11, characterized in that, The fabrication steps of the connecting layer and the transition layer include: Under inert gas protection, a magnetron sputtering target is activated on the surface of the reinforcing layer of the substrate. The target includes at least one of titanium target, zirconium target, silicon target, niobium target, and chromium target to form a bonding layer. A carbon source gas is introduced and deposited on the surface of the connecting layer. The flow rate of the carbon source gas is gradually increased from 30 Sccm to 300 Sccm to form a transition layer. The mass percentage of carbon atoms in the transition layer gradually increases from the side closer to the connecting layer to the side closer to the TaC film.
15. The method for preparing the composite material according to claim 11, characterized in that, The fabrication steps of the connecting layer and the transition layer include: Under inert gas protection, silicon source gas is introduced and deposited on the surface of the reinforcing layer of the substrate to form a bonding layer, wherein the bonding layer is a silicon layer; A carbon source gas is introduced and deposited on the surface of the silicon layer. The flow rate of the carbon source gas is gradually increased from 30 Sccm to 300 Sccm to form a transition layer. The mass percentage of carbon atoms in the transition layer gradually increases from the side closer to the silicon layer to the side closer to the TaC film.
16. The method for preparing the composite material according to claim 11, characterized in that, The preparation steps of the TaC film include: A graphite target is deposited onto the surface of the transition layer using a filtered arc ion plating or arc ion plating process, with a deposition temperature ≤200℃, to form a TaC film.
17. A wear-resistant structural component, characterized in that, The wear-resistant structural component is prepared using the composite material as described in claims 1-10.
18. A rotating shaft, characterized in that, Including the wear-resistant structural component as described in claim 17.
19. A foldable screen, characterized in that, Includes the rotating shaft as described in claim 18.
20. An electronic device, characterized in that, Including the wear-resistant structural component as described in claim 17.