Metallic glass / graphite composite material with mineral bridge structure and preparation method thereof

Abstract

The invention belongs to the technical field of preparation of amorphous composite materials, and particularly relates to a metallic glass / graphite composite material with a mineral bridge structure and a preparation method of the metallic glass / graphite composite material. Comprising the following steps: etching a plurality of graphite flakes by adopting a laser processing mode, and forming a plurality of holes which are uniformly distributed in each graphite flake; the graphite flake layers are uniformly distributed and arranged in the thickness direction and then fixed, a metal glass matrix is melted and then injected, all the graphite flake layers and all the open pores are filled with the metal glass matrix in a suction casting mode, a metal glass layer is formed on the surface of each graphite flake layer in a suction casting mode, and the metal glass / graphite composite material is obtained. According to the invention, the uniformly distributed open pore structures are formed on the surface of the graphite flake through a laser processing technology, and the graphite flake layer forms a mineral bridge structure among all the metal glass layers, so that strong binding force is formed between the graphite flake and the metal glass substrate, the graphite flake is ensured not to fall off easily under high load or impact load, and the stability is greatly improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of amorphous composite material preparation, and particularly relates to a metallic glass / graphite composite material with a mineral bridge structure and a preparation method thereof. Background Art

[0002] Metallic glasses are a class of alloy materials with an irregular atomic structure, and usually have excellent mechanical properties, including high strength, high hardness, good corrosion resistance, and good thermal stability. However, the inherent brittleness of metallic glasses makes them prone to fracture when subjected to dynamic loads or impact loads, which limits their application in certain fields (such as environments with high-intensity friction and wear resistance). Therefore, how to improve the toughness of metallic glasses and enhance their reliability under complex use conditions has always been the focus of related research.

[0003] Currently, one of the common methods to improve the toughness of metallic glasses is through the design of composite materials, introducing reinforcing phases (such as carbon fibers, ceramic particles, graphite, etc.) into the metallic glass matrix. Especially adding graphite materials to metallic glasses has been proven to effectively improve the toughness and crack resistance of metallic glasses. Due to its excellent lubricity and low friction coefficient, graphite materials can significantly reduce the wear rate of metallic glasses and improve their wear resistance. The existing method of adding graphite materials to metallic glasses is to directly introduce graphite particles into the metallic glass matrix, and prepare metallic glass / graphite composite materials through methods such as melting, stirring casting, etc. In this method, graphite particles are dispersed in the metallic glass matrix, hoping to improve the wear resistance of the composite material through the lubrication characteristics of graphite, and at the same time alleviate the brittleness problem of metallic glasses through the presence of graphite. Although introducing graphite materials can improve the toughness to a certain extent, in the forming technology, graphite particles often cannot be tightly combined with the metallic glass matrix, the forming process is often complex, it is difficult to ensure the uniform distribution of graphite particles, and the interfacial bonding force between graphite and metallic glass is weak. Due to the layered structure and high lubricity of graphite, the lubrication performance under high loads is not persistent, graphite particles are prone to wear, fall off or move under external forces, the stability is insufficient, and it is impossible to maintain its lubrication effect for a long time and it is difficult to significantly improve the toughness of metallic glasses, resulting in unstable mechanical properties of the composite material.

[0004] Based on this, in the prior art, graphite is also coated on the surface of metallic glass to form a lubricating layer. By utilizing the self-lubricating property of graphite, the friction performance of the surface of metallic glass is improved, and the service life of metallic glass is prolonged. Although it can provide initial lubrication, the graphite coating mainly relies on physical adsorption or chemical adhesion, and this binding force is relatively weak. However, in an environment of high load and high friction, the coating is also prone to wear or peeling. Especially in long-term use or extreme working conditions, the stability of the coating cannot be effectively guaranteed, and the graphite coating only exists on the surface of the material and fails to provide toughening effect inside the composite material. Therefore, its improvement on the toughness of metallic glass is limited. Especially when the material bears large internal forces or stress concentration, the coating is difficult to effectively disperse stress, and thus cannot effectively prevent the brittle fracture of metallic glass. Summary of the Invention

[0005] To solve the above problems, the present invention provides a metallic glass / graphite composite material with a mineral bridge structure and a preparation method thereof. High-purity graphite flakes are used as reinforcing materials. Through laser processing technology, a uniformly distributed open-hole structure is formed on the surface of the graphite flakes. After arranging multiple graphite flakes evenly in the thickness direction and fixing them to form a precursor, the metallic glass matrix is melted and suction-cast, so that it fully fills between the graphite flake layers and the open holes. The graphite flake layers form a mineral bridge structure between all the metallic glass layers, forming a strong binding force between the graphite flakes and the metallic glass matrix, ensuring that the graphite flakes are not easily detached under high load or impact load, greatly improving the stability, and realizing the toughening and self-lubricating properties of metallic glass.

[0006] The present invention solves the above technical problems through the following technical solutions.

[0007] The first object of the present invention is to provide a preparation method of a metallic glass / graphite composite material with a mineral bridge structure, including the following steps:

[0008] S1. By means of laser processing, multiple graphite flakes are etched to form a plurality of uniformly arranged open holes on each graphite flake, obtaining a plurality of graphite flake layers.

[0009] S2. After arranging multiple graphite flake layers evenly in the thickness direction and fixing them to form a precursor, the metallic glass matrix is melted and then injected onto the precursor for rapid cooling and casting, so that the metallic glass matrix is suction-cast and filled onto all the graphite flake layers and into all the open holes. A metallic glass layer is suction-cast and formed on the surface of each graphite flake layer. The graphite flake layers form a mineral bridge structure between all the metallic glass layers, obtaining the metallic glass / graphite composite material.

[0010] Furthermore, the layer spacing between adjacent graphite flake layers is 0.2 mm to 2 mm.

[0011] Furthermore, the layer thickness ratio of the metallic glass layer to the graphite sheet layer is 2 to 40:1.

[0012] Furthermore, the thickness of the metallic glass layer is 0.2 mm to 2 mm, and the thickness of the graphite sheet layer is 0.05 mm to 0.5 mm.

[0013] Furthermore, the opening density on each graphite sheet layer is 5% to 80%.

[0014] Furthermore, the aperture of the opening is 100 μm to 1000 μm.

[0015] Furthermore, the wavelength of the laser processing is 355 nm, the pulse frequency is 20 KHz to 40 KHz, the power is 5 W to 10 W, and the scanning speed is 150 mm / s to 200 mm / s.

[0016] Furthermore, after the rapid cooling casting is completed, the surface of the metallic glass / graphite composite material is polished until the surface roughness is less than 0.1 μm.

[0017] Furthermore, the metallic glass matrix is Cu 36 Zr 48 Ag 8 Al 8 .

[0018] The second object of the present invention is to provide a metallic glass / graphite composite material prepared by the above preparation method.

[0019] The present invention has the following beneficial effects compared with the prior art:

[0020] Based on the BMG rapid cooling suction casting forming method, when the BMG is suction cast, the melt is fully filled into the graphite sheet layer and graphite sheet holes etched with regular micropores to form the "mineral bridge" structure in the composite material. Specifically, graphite sheets are used as reinforcing materials, and uniformly distributed open holes are etched on the graphite sheets by laser processing. Subsequently, the metallic glass is suction cast into the graphite sheets and round holes in the molten state. The graphite sheet layer forms a mineral bridge structure between all metallic glass layers, thereby forming a strong bonding force between the graphite sheet and the metallic glass matrix. This strong bonding force can ensure that the graphite sheet is not easily detached under high load or impact load, avoiding the problem that traditional graphite particles are easily detached, and greatly improving the stability. When the mineral bridge structure bears external forces, it can effectively disperse stress, alleviate the brittle fracture tendency of the metallic glass matrix, and improve the impact resistance of the material under complex working conditions. At the same time, the mineral bridge structure can relieve the stress concentration inside the metallic glass and significantly improve its toughness. Secondly, the graphite sheets are uniformly distributed inside the material. Due to the unique self-lubricating performance of high-purity graphite sheets, it can be effectively utilized in the metallic glass / graphite composite material, continuously play a lubricating role during use, reduce the friction coefficient, reduce wear, and extend the service life of the material. Therefore, this composite material can maintain stable lubricating performance in high-temperature and high-friction environments for a long time.

[0021] The present invention adopts laser processing combined with an integrated forming technology, enabling the metallic glass matrix and the graphite sheet to form a uniform composite structure in the same process. Laser processing has the characteristics of high precision and high energy density, and can precisely control the diameter and density of the mineral bridge, thereby ensuring the stability and consistency of the composite material throughout the service life. Brief Description of the Drawings

[0022] Figure 1 It is the process flow diagram for the preparation of the metallic glass / graphite composite material of the present invention.

[0023] Figure 2 It is the structural diagram of the prefabricated card slot of the present invention.

[0024] Figure 3 It is the structural diagram of the copper mold of the present invention.

[0025] Figure 4 It is the optical microscope image of the graphite sheet layer prepared in Examples 1 to 5 of the present invention. Figure 4 Among them, (a) is Example 1, (b) is Example 2, (c) is Example 3, (d) is Example 4, and (e) is Example 5.

[0026] Figure 5 It is the EDS spectrum of the graphite sheet layer prepared in Examples 1 to 5 of the present invention.

[0027] Figure 6SEM images of the BMG / graphite layered composites prepared in Example 1 and Example 3 of the present invention Figure 6 Among them, (a) is for Example 3 and (b) is for Example 1.

[0028] Figure 7 SEM image and EDS spectrum of the interface of the BMG / graphite layered composite prepared in Example 1 of the present invention Figure 7 Among them, (a) is the SEM image of the interface and (b) is the EDS spectrum.

[0029] Figure 8 Load-displacement curve diagrams of the bulk BMG and the BMG / graphite layered composites prepared in Examples 1 to 5 of the present invention Figure 8 Among them, (a) is for the bulk BMG, (b) is for Example 1, (c) is for Example 2, (d) is for Example 3, (e) is for Example 4, and (f) is for Example 5.

[0030] Figure 9 Morphology diagram of fatigue fracture crack propagation of the BMG / graphite layered composite prepared in Example 1 of the present invention Figure 9 Among them, (a) is the diagram of deflection when the crack penetrates the layer and (b) is the diagram of bifurcation during crack deflection.

[0031] Figure 10 Schematic diagram of the fracture mechanism of the BMG / graphite layered composite prepared by the present invention

[0032] Figure 11 Friction coefficient and wear rate diagrams of the BMG / graphite layered composite prepared in Example 1 of the present invention under different applied loads Figure 11 Among them, (a) is the friction coefficient diagram and (b) is the wear rate diagram.

[0033] Figure 12 Friction coefficient and wear rate diagrams of the BMG / graphite layered composite prepared in Example 1 of the present invention at different frequencies Figure 12 Among them, (a) is the friction coefficient diagram and (b) is the wear rate diagram.

[0034] Figure 13 Friction coefficient curve diagrams of the material under different loads and sliding frequencies of the present invention Figure 13 Among them, (a) is for different sliding frequencies and (b) is for different loads.

[0035] Figure 14 Friction coefficient curve and three-dimensional morphology diagram of the wear scar of the BMG / graphite layered composite under the conditions of 4 MPa, 20 Hz, and a stroke of 500 m in Example 1 of the present invention Figure 14 Among them, (a) is the friction coefficient curve diagram and (b) is the three-dimensional morphology diagram of the wear scar.

[0036] Figure 15 This is the wear scar morphology of the BMG / graphite laminated composite material under the conditions of 4 MPa, 20 Hz and 2 MPa, 20 Hz in Example 1 of the present invention. Figure 15 In (a), it is 4 MPa, 20 Hz, in (b), it is 2 MPa, 20 Hz, and in (c), it is 2 MPa, 20 Hz in the relevant wear track diagram.

[0037] Figure 16 This is the wear scar morphology and EDS spectrum of the mating block BMG of the present invention. Figure 16 In (a), it is the wear scar morphology, and in (b), it is the EDS spectrum.

[0038] Figure 17 This is the partial enlarged view of the wear scar of the BMG / graphite laminated composite material in Example 1 of the present invention. Figure 17 In (b), it is the enlarged view of the framed part in (a).

[0039] Figure 18 This is the present invention Figure 17 The surface distribution diagram of the elements in Figure (b) of the present invention. Figure 18 In (a), it is the C element, in (b), it is the Zr element, in (c), it is the Cu element, in (d), it is the Ag element, in (e), it is the Al element, and in (f), it is the O element. Detailed implementation manners

[0040] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present invention.

[0041] It should be noted that the professional terms used in the present invention are only for the purpose of describing specific embodiments, and are not intended to limit the protection scope of the present invention. In the present invention, certain terms are used to refer to specific components. Those skilled in the art should understand that technicians may use different nouns to refer to the same component. The present invention does not distinguish components by the difference in nouns, but by the difference in the functions of components. As mentioned throughout the specification and claims, "including" is an open-ended term, so it should be understood as "including but not limited to".

[0042] In existing metallic glass / graphite composites, firstly, graphite particles often exhibit uneven distribution. Due to the layered structure and lubricating properties of graphite, the bonding force between graphite particles and the metallic glass matrix is relatively poor. Especially in traditional methods such as smelting and casting, graphite particles are prone to aggregation or precipitation, resulting in insufficient bonding force between graphite and metallic glass, and being unable to maintain the stability and distribution of graphite particles under high load or impact load, thereby affecting the overall mechanical properties and durability of the composite material. Secondly, the inherent brittleness of metallic glass makes it prone to fracture under high-stress environments, limiting its application in some complex working conditions. Although the toughness of metallic glass can be improved by introducing graphite reinforcement phase, due to the insufficient dispersion of graphite particles and poor bonding force with the matrix in existing technologies, the toughening effect of the composite material is not obvious. Especially under high stress or impact load, metallic glass is still prone to brittle fracture. Thirdly, the lubricating properties of metallic glass / graphite composites are often difficult to last. Especially in environments with high load, high temperature and high friction, graphite particles are prone to falling off or being worn, resulting in a rapid decline in lubricating properties. Existing graphite coating technologies also face similar problems, and the surface of the coating is prone to wear and lose the lubricating effect. Finally, the forming process is usually relatively complex, and it is difficult to ensure the uniform distribution of graphite particles and the metallic glass matrix. During the forming process of the composite material, due to reasons such as thermal stress and uneven particle size, the interface between graphite and metallic glass is unstable, resulting in problems such as uneven performance and unstable quality during the use of the composite material.

[0043] Based on the above problems, the present invention provides a preparation method for a metallic glass / graphite composite material with a mineral bridge structure. The preparation process is as Figure 1 shown and includes the following steps:

[0044] S1. By means of laser processing, etch multiple graphite sheets to form a plurality of uniformly arranged openings on each graphite sheet, and obtain a plurality of graphite sheet layers.

[0045] S2. Uniformly arrange and fix a plurality of graphite sheet layers in the thickness direction to form a precursor. Melt the metallic glass matrix and inject it onto the precursor for rapid cooling and casting to form a shape, so that the metallic glass matrix is suction-cast and filled onto all graphite sheet layers and into all openings. A metallic glass layer is suction-cast and formed on the surface of each graphite sheet layer, and the graphite sheet layers form a mineral bridge structure between all metallic glass layers, obtaining a metallic glass / graphite composite material.

[0046] The present invention is based on the BMG rapid cooling suction casting forming method. During the BMG suction casting forming, the melt is fully filled into the graphite sheet layer and graphite sheet holes etched with regular micropores to form the "mineral bridge" structure in the composite material. Specifically, graphite sheets are used as reinforcing materials, and uniformly distributed openings are etched on the graphite sheets by laser processing. Subsequently, the metallic glass is suction cast into the graphite sheets and round holes in the molten state. The graphite sheet layer forms a mineral bridge structure between all metallic glass layers, thereby forming a strong bonding force between the graphite sheet and the metallic glass matrix. This strong bonding force can ensure that the graphite sheet is not easily detached under high load or impact load, avoiding the problem that traditional graphite particles are prone to detachment, and greatly improving the stability; the formed mineral bridge structure can effectively disperse stress when bearing external forces, alleviate the brittle fracture tendency of the metallic glass matrix, and improve the impact resistance of the material under complex working conditions. At the same time, the mineral bridge structure can relieve the stress concentration inside the metallic glass and significantly improve its toughness; secondly, the graphite sheets are uniformly distributed inside the material. Due to the unique self-lubricating performance of high-purity graphite sheets, it is effectively utilized in the metallic glass / graphite composite material, can continuously play a lubricating role during use, reduce the friction coefficient, reduce wear, and extend the service life of the material. Therefore, this composite material can maintain stable lubricating performance in high-temperature and high-friction environments for a long time.

[0047] The present invention adopts laser processing combined with an integrated forming technology, enabling the metallic glass matrix and the graphite sheet to form a uniform composite structure in the same process, where the rapid cooling casting forming adopts the existing conventional arc melting - copper mold suction casting process.

[0048] In a specific embodiment, the layer spacing between adjacent graphite sheet layers is 0.2 mm to 2 mm. In the present invention, a prefabricated card slot is used to fix the graphite sheet layer to control the layer spacing between adjacent graphite sheet layers. As a preferred embodiment, the prefabricated card slot is prepared from an aluminum sheet with a thickness of 0.8 mm, and the prefabricated card slot structure is obtained by laser processing with a Nd:YAG laser. The wavelength of the laser processing is 355 nm, the pulse frequency is 20 KHz to 40 KHz, the power is 5 W to 10 W, and the scanning speed is 150 mm / s to 200 mm / s. As Figure 2 described, the groove width of the prefabricated card slot is 0.22 mm, the depth is 0.3 mm, and the center spacing is 1 mm. Before using the prefabricated card slot, the prefabricated card slot is placed in acetone and ultrasonically cleaned to remove surface impurities.

[0049] In a specific embodiment, the layer thickness ratio of the metallic glass layer to the graphite sheet layer is 2 to 40:1, the thickness of the metallic glass layer is 0.2 mm to 2 mm, and the thickness of the graphite sheet layer is 0.05 mm to 0.5 mm. In a preferred embodiment, the layer thickness ratio of the metallic glass layer to the graphite sheet layer is 4:1, the thickness of the metallic glass layer is 0.8 mm, and the thickness of the graphite sheet layer is 0.2 mm. In the present invention, asFigure 3 As shown in Figure 3 , the number of graphite sheet layers is two. Fix two prefabricated card slots to two opposite faces inside the copper mold, and then insert the graphite sheets into the corresponding prefabricated card slots. The inner diameter size of the copper mold is 65mm×5mm×5mm. Suck and cast the molten master alloy into the copper mold for casting and forming.

[0050] In a specific embodiment, the opening density on each graphite sheet layer is 5% - 80%. In the present invention, according to the surface micropore density formula: ε = πD 2 / 4l 2 . Where ε is the areal density, %; D is the diameter, mm; l is the center spacing, mm; fix the diameter of the opening, and etch micropores with different areal densities on the graphite sheet layer. In some preferred embodiments, the micropore densities are 5%, 10%, 20%, 40%, 60%, and the corresponding micropore center spacings are 2.7mm, 2.0mm, 1.4mm, 1.0mm, 0.8mm.

[0051] In a specific embodiment, the aperture diameter of the opening is 100μm - 1000μm.

[0052] In a specific embodiment, the wavelength of the laser processing is 355nm, the pulse frequency is 20KHz - 40KHz, the power is 5W - 10W, and the scanning speed is 150mm / s - 200mm / s. In the present invention, use a diamond wire cutting machine to cut a high-purity graphite block into a graphite thin sheet with a size of 0.21mm×61mm×28mm, and use a Nd:YAG laser to etch regularly arranged openings on the graphite thin sheet. After the laser processing is completed, immerse the graphite sheet with the microporous structure in acetone and ultrasonically clean it for 5 minutes to remove the impurities and graphite powder attached to the surface. Laser processing has the characteristics of high precision and high energy density, and can precisely control the diameter and density of the mineral bridges, thereby ensuring the stability and consistency of the composite material during the entire service life.

[0053] In a specific embodiment, after the rapid cooling casting and forming is completed, polish the surface of the metallic glass / graphite composite material until the surface roughness is less than 0.1μm.

[0054] In a specific embodiment, the metallic glass matrix is Cu 36 Zr 48 Ag 8 Al 8 .

[0055] The following is further illustrated through specific embodiments.

[0056] Example 1

[0057] This example provides a preparation method for a metallic glass / graphite composite material with a mineral bridge structure. The preparation process is asFigure 1 As shown, it includes the following steps:

[0058] S1. Use a diamond wire cutting machine to cut a high-purity graphite block into graphite flakes with dimensions of 0.21 mm × 61 mm × 28 mm. Adopt the laser processing method, and use a Nd:YAG laser to etch regularly arranged micropores on two graphite flakes. The laser processing parameters are set as follows: wavelength is 355 nm, pulse frequency is 30 KHz, power is 7.5 W, scanning speed is 200 mm / s, the diameter of the micropores is 500 μm, the micropore density is 60%, and the corresponding center distance between micropores is 0.8 mm. After the laser processing is completed, immerse the graphite sheet with the micropore structure in acetone and ultrasonically clean it for 5 min to remove the impurities and graphite powder attached to the surface. Obtain two graphite sheet layers.

[0059] S2. Prepare a prefabricated card slot using a 0.8-mm aluminum sheet. Through the price of the Nd:YAG laser, the wavelength of the laser processing is 355 nm, the pulse frequency is 30 KHz, the power is 7.5 W, the scanning speed is 200 mm / s, the groove width of the prefabricated card slot is 0.22 mm, the depth is 0.3 mm, and the center distance is 1 mm to obtain the prefabricated card slot. Before using the prefabricated card slot, place the prefabricated card slot in acetone and ultrasonically clean it to remove the surface impurities; then fix the two prefabricated card slots to two opposite faces inside the copper mold. The inner diameter dimensions of the copper mold are 65 mm × 5 mm × 5 mm, and insert the graphite sheet into the corresponding prefabricated card slot.

[0060] S3. Melt the metallic glass matrix and inject it onto the precursor, and use the arc melting - copper mold suction casting process for rapid solidification casting to enable the metallic glass matrix to be suction-cast and filled onto all graphite sheet layers and into all micropores. A metallic glass layer is formed by suction-casting on the surface of each graphite sheet layer, and the graphite sheet layers form a mineral bridge structure between all metallic glass layers to obtain a metallic glass / graphite composite material, named BMG / graphite laminated composite material.

[0061] Example 2

[0062] This example provides a preparation method for a metallic glass / graphite composite material with a mineral bridge structure. The preparation process is as Figure 1 shown, including the following steps:

[0063] S1. Use a diamond wire cutting machine to cut high-purity graphite blocks into graphite flakes with dimensions of 0.21 mm × 61 mm × 28 mm. Adopt the method of laser processing. Use a Nd:YAG laser to etch regularly arranged micro-holes on two graphite flakes. The laser processing parameters are set as follows: the wavelength is 355 nm, the pulse frequency is 30 KHz, the power is 7.5 W, the scanning speed is 200 mm / s, the diameter of the micro-holes is 500 μm, the micro-hole density is 40%, and the corresponding center distance between micro-holes is 1.0 mm. After the laser processing is completed, immerse the graphite flakes with micro-hole structures in acetone and ultrasonically clean them for 5 min to remove the impurities and graphite powder attached to the surface. Obtain two graphite sheet layers.

[0064] S2. Prepare a prefabricated card slot using a 0.8-mm aluminum sheet. Through the price of the Nd:YAG laser, the wavelength of the laser processing is 355 nm, the pulse frequency is 30 KHz, the power is 7.5 W, the scanning speed is 200 mm / s, the groove width of the prefabricated card slot is 0.22 mm, the depth is 0.3 mm, and the center distance is 1 mm to obtain the prefabricated card slot. Before using the prefabricated card slot, place the prefabricated card slot in acetone and ultrasonically clean it to remove the surface impurities; then fix the two prefabricated card slots to two opposite faces inside the copper mold. The inner diameter size of the copper mold is 65 mm × 5 mm × 5 mm, and insert the graphite flakes into the corresponding prefabricated card slots.

[0065] S3. Melt the metallic glass matrix and inject it onto the precursor, and use the arc melting - copper mold suction casting process to rapidly cool and cast into shape, so that the metallic glass matrix is suction-cast and filled onto all graphite sheet layers and into all micro-holes. A metallic glass layer is suction-cast and formed on the surface of each graphite sheet layer. The graphite sheet layers form a mineral bridge structure between all metallic glass layers to obtain a metallic glass / graphite composite material, named BMG / graphite laminated composite material.

[0066] Example 3

[0067] This example provides a preparation method for a metallic glass / graphite composite material with a mineral bridge structure. The preparation process is as Figure 1 shown, including the following steps:

[0068] S1. Use a diamond wire cutting machine to cut a high-purity graphite block into graphite flakes with dimensions of 0.21 mm × 61 mm × 28 mm. By means of laser processing, use a Nd:YAG laser to etch regularly arranged micro-holes on two graphite flakes. The laser processing parameters are set as follows: wavelength is 355 nm, pulse frequency is 30 KHz, power is 7.5 W, scanning speed is 200 mm / s, the diameter of the micro-holes is 500 μm, the micro-hole density is 20%, and the corresponding center distance between micro-holes is 1.4 mm. After the laser processing is completed, immerse the graphite flakes with micro-hole structures in acetone and ultrasonically clean them for 5 min to remove the impurities and graphite powder attached to the surface. Obtain two graphite sheet layers.

[0069] S2. Prepare a prefabricated card slot using a 0.8-mm aluminum sheet. By means of Nd:YAG laser processing, the laser processing wavelength is 355 nm, the pulse frequency is 30 KHz, the power is 7.5 W, the scanning speed is 200 mm / s, the groove width of the prefabricated card slot is 0.22 mm, the depth is 0.3 mm, and the center distance is 1 mm. Obtain the prefabricated card slot. Before using the prefabricated card slot, place the prefabricated card slot in acetone and ultrasonically clean it to remove the surface impurities; then fix the two prefabricated card slots to two opposite faces inside a copper mold. The inner diameter dimensions of the copper mold are 65 mm × 5 mm × 5 mm, and insert the graphite flakes into the corresponding prefabricated card slots.

[0070] S3. Melt the metallic glass matrix and inject it onto the precursor, and use the arc melting - copper mold suction casting process to rapidly cool and cast it into shape, so that the metallic glass matrix is suction-cast and filled onto all graphite sheet layers and into all micro-holes. A metallic glass layer is suction-cast and formed on the surface of each graphite sheet layer, and the graphite sheet layers form a mineral bridge structure between all metallic glass layers to obtain a metallic glass / graphite composite material, named BMG / graphite laminated composite material.

[0071] Example 4

[0072] This example provides a preparation method for a metallic glass / graphite composite material with a mineral bridge structure. The preparation process is as Figure 1 shown, including the following steps:

[0073] S1. Use a diamond wire cutting machine to cut high-purity graphite blocks into graphite flakes with dimensions of 0.21 mm × 61 mm × 28 mm. By means of laser processing, use a Nd:YAG laser to etch regularly arranged micro-holes on two graphite flakes. The laser processing parameters are set as follows: wavelength is 355 nm, pulse frequency is 30 KHz, power is 7.5 W, scanning speed is 200 mm / s, the diameter of the micro-holes is 500 μm, the micro-hole density is 10%, and the corresponding center distance between micro-holes is 2.0 mm. After the laser processing is completed, immerse the graphite flakes with micro-hole structures in acetone and ultrasonically clean them for 5 min to remove the impurities and graphite powder attached to the surface. Obtain two graphite sheet layers.

[0074] S2. Prepare a prefabricated card slot using a 0.8-mm aluminum sheet. By means of Nd:YAG laser processing, the wavelength of the laser processing is 355 nm, the pulse frequency is 30 KHz, the power is 7.5 W, the scanning speed is 200 mm / s, the groove width of the prefabricated card slot is 0.22 mm, the depth is 0.3 mm, and the center distance is 1 mm to obtain the prefabricated card slot. Before using the prefabricated card slot, place the prefabricated card slot in acetone and ultrasonically clean it to remove the surface impurities; then fix the two prefabricated card slots to two opposite faces inside a copper mold. The inner diameter dimensions of the copper mold are 65 mm × 5 mm × 5 mm, and insert the graphite flakes into the corresponding prefabricated card slots.

[0075] S3. Melt the metallic glass matrix and inject it onto the precursor, and use the arc melting - copper mold suction casting process to rapidly cool and cast it into shape, so that the metallic glass matrix is suction-cast and filled onto all graphite sheet layers and into all micro-holes. A metallic glass layer is suction-cast and formed on the surface of each graphite sheet layer, and the graphite sheet layers form a mineral bridge structure between all metallic glass layers to obtain a metallic glass / graphite composite material, named BMG / graphite laminated composite material.

[0076] Example 5

[0077] This example provides a preparation method for a metallic glass / graphite composite material with a mineral bridge structure. The preparation process is as Figure 1 shown, including the following steps:

[0078] S1. Use a diamond wire cutting machine to cut a high-purity graphite block into graphite flakes with dimensions of 0.21 mm × 61 mm × 28 mm. Adopt the method of laser processing, and use a Nd:YAG laser to etch regularly arranged micro-holes on two graphite flakes. The laser processing parameters are set as follows: the wavelength is 355 nm, the pulse frequency is 30 KHz, the power is 7.5 W, the scanning speed is 200 mm / s, the diameter of the micro-holes is 500 μm, the micro-hole density is 5%, and the corresponding center distance between micro-holes is 2.7 mm. After the laser processing is completed, immerse the graphite flakes with the micro-hole structure in acetone and ultrasonically clean for 5 min to remove the impurities and graphite powder attached to the surface, and obtain two graphite sheet layers.

[0079] S2. Prepare a prefabricated card slot using a 0.8-mm aluminum sheet. Through the price of the Nd:YAG laser, the wavelength of the laser processing is 355 nm, the pulse frequency is 30 KHz, the power is 7.5 W, the scanning speed is 200 mm / s, the groove width of the prefabricated card slot is 0.22 mm, the depth is 0.3 mm, and the center distance is 1 mm to obtain the prefabricated card slot. Before using the prefabricated card slot, place the prefabricated card slot in acetone and ultrasonically clean to remove the surface impurities; then fix the two prefabricated card slots to two opposite faces inside the copper mold. The inner diameter size of the copper mold is 65 mm × 5 mm × 5 mm, and insert the graphite sheet layer into the corresponding prefabricated card slot.

[0080] S3. Melt the metallic glass matrix and inject it onto the precursor, and use the arc melting - copper mold suction casting process to rapidly cool and cast into shape, so that the metallic glass matrix is suction-cast and filled onto all graphite sheet layers and into all micro-holes. A metallic glass layer is formed by suction-casting on the surface of each graphite sheet layer, and the graphite sheet layers form a mineral bridge structure between all metallic glass layers to obtain a metallic glass / graphite composite material, named BMG / graphite layered composite material.

[0081] Test the structures and properties of the graphite sheet layers and the prepared metallic glass / graphite composite materials prepared in Examples 1 to 5. The results are as follows:

[0082] Figure 4 This is the optical microscope image of the graphite sheet layers prepared in Examples 1 to 5 of the present invention. Figure 4 In (a) is Example 1, (b) is Example 2, (c) is Example 3, (d) is Example 4, and (e) is Example 5. As Figure 4 shown, by using the laser etching technology in Examples 1 to 5, micro-holes with controllable density, adjustable size, and regular arrangement can be prepared on the graphite layer. The micro-hole patterns are clear, the diameters are all 500 μm, the center distances are 0.8 mm, 1.0 mm, 1.4 mm, 2.0 mm, and 2.7 mm respectively, and the corresponding micro-hole surface densities are 60%, 40%, 20%, 10%, and 5% respectively.

[0083] Figure 5 The EDS spectra of the graphite sheets prepared in Examples 1 to 5 of the present invention are shown in FIG. Figure 5 As described above, the graphite flakes have a single composition and are only composed of graphite phase, and the rapid cooling casting process will not have a negative impact on the composition of the metallic glass.

[0084] Figure 6 The SEM images of the BMG / graphite layered composite materials prepared in Examples 1 and 3 of the present invention are shown in FIG. Figure 6 (a) is Example 3, and (b) is Example 1. Figure 6 As shown in the figure, the dark layer is the graphite layer, and the light layer is the BMG layer. The graphite layer is obviously thinner than the BMG layer, with a thickness of about 200μm. In addition, due to the existence of the microporous structure, the adjacent metal layers are not completely isolated by the graphite layer, but are connected by the metal "mineral bridge" constructed in the graphite layer to form a bridge structure. This structure can not only increase the contact area to improve the interface bonding strength, but also effectively utilize the connected alloy to control the interlayer slip and prevent interlayer cracking.

[0085] Figure 7 The SEM image and EDS spectrum of the interface of the BMG / graphite layered composite material prepared in Example 3 of the present invention are shown in FIG. Figure 7 (a) is the SEM image of the interface, and (b) is the EDS spectrum. From the enlarged image of the interface between the two phases, it can be seen that the layered structure is clear and the interface layer is straight, without microcracks or interlayer cracks. EDS testing shows that the chemical composition of the layered composite material is only graphite and BMG, and no chemical reaction occurs between the two phases during the molding process.

[0086] Figure 8 The load-displacement curves of the block BMG of the present invention and the BMG / graphite layered composite materials prepared in Examples 1 to 5 are shown in FIG. Figure 8 (a) is a bulk BMG, (b) is Example 1, (c) is Example 2, (d) is Example 3, (e) is Example 4, and (f) is Example 5. Figure 8 As shown, it can be seen that the bulk BMG exhibits typical brittle fracture characteristics, and the BMG / graphite layered composite material exhibits "non-catastrophic" fracture characteristics. The initial crack initiation does not lead to rapid destruction of the material, but is passivated under the action of the metal bearing layer and the metal "bridge" structure, and the crack propagation through the layer is hindered. There are multiple load reduction phenomena in the load-displacement curve. The fracture of the "bridge" structure causes a slight decrease in the load. When the applied load continues to increase, the crack is transferred from the previous bearing layer to the next bearing layer, and the fracture of the matrix layer causes a significant decrease in the load. This is repeated, showing a staged destruction feature until the layered material fails completely.

[0087] Figure 9 This is a fatigue fracture crack propagation morphology of the BMG / graphite layered composite material prepared in Example 3 of the present invention. Figure 9 (a) is the deflection diagram when the crack penetrates the layer, and (b) is the bifurcation diagram when the crack deflects. Figure 9 As shown in the figure, it can be seen that the crack deflects and bifurcates between the layers, and propagates a certain distance in the weak interface layer before turning into the metal layer. During the fracture process, multiple crack extension paths appear in the same layer structure, and cracks between different layers deflect, resulting in local delamination. Crack passivation, crack deflection and bifurcation can effectively consume fracture energy and release stress, so that the material can consume more fracture energy when it fails, preventing the material from catastrophic brittle fracture.

[0088] Based on the above analysis, the fracture mechanism of BMG / graphite layered composites is summarized. Figure 10 FIG. 1 is a schematic diagram of the fracture mechanism of the BMG / graphite layered composite material prepared in the present invention. Figure 10 As shown in the figure, BMG is a brittle material. For BMG / graphite layered composite materials without metal "bridge" structure, under external force loading, the deformation of the material is highly localized and the deformation is small. When subjected to force, a large stress concentration is caused locally in the BMG layer, causing the BMG layer to be unstable and brittle. Graphite has poor wettability with alloys, and the sliding resistance between the metal layer and the graphite layer is low, resulting in interlayer debonding and interlayer fracture. By constructing an interface "bridge" structure, the two adjacent metal layers can be connected, and the interface bonding strength and sliding resistance between graphite and metal can be improved to prevent the occurrence of interlayer fracture. When the material is deformed by force, the "bridge" structure between the metal layers can disperse the stress concentration at the crack tip and increase the material's bearing capacity. Once the external force exceeds the limit, the "bridge" structure breaks, resulting in a small range of stress reduction on the load-displacement curve. When the effective "bridge" structure at the force-bearing part fails completely, the crack will pass through the weak interface layer and enter the next reinforcement layer. The multiple bifurcation and deflection of the crack in the layer can effectively dissipate the fracture energy and prevent the occurrence of catastrophic fracture of the material.

[0089] In summary, the density of the metal "bridge" structure in the BMG / graphite layered composite has a significant impact on the fracture behavior and mechanism of the composite. The "bridge" structure between metal layers can effectively dissipate the stress concentration at the crack tip. Therefore, the higher the density of the "bridge" structure, the more conducive it is to preventing the stress concentration at the crack tip, passivating the crack, dissipating more fracture energy by inducing crack bifurcation and deflection, and thus improving the fracture behavior of the material. However, an overly dense "bridge" structure will increase the interlayer restraint, which is not conducive to material deformation and the dissipation of crack propagation energy. On the other hand, an overly sparse "bridge" structure between metal layers is difficult to resist the stress concentration at the crack tip, and the slip resistance will be greatly reduced, resulting in interlayer debonding, crack penetration along the layer, and ultimately catastrophic interlayer fracture. Therefore, synthesizing and designing the metal "bridge" structure between adjacent metal layers can significantly improve the interfacial bonding strength of the BMG / graphite layered composite and cause the material to undergo non-brittle fracture when stressed. To obtain a BMG / graphite layered composite with better toughening effect, it is necessary to reasonably regulate the layer structure (number of layers, layer thickness, layer thickness ratio) and metal "bridge" structure parameters (shape, density, length).

[0090] To explore the operational reliability of the designed BMG / graphite layered composite, the present invention studies the working condition adaptability of the BMG / graphite layered composite under different friction conditions. Figure 11 This is the friction coefficient and wear rate diagram of the BMG / graphite layered composite prepared in Example 3 of the present invention under different applied loads. Figure 11 In which, (a) is the friction coefficient diagram and (b) is the wear rate diagram. As Figure 11 shown, it can be seen that the BMG / graphite layered composite exhibits excellent tribological properties under different conditions. As the load increases, both the friction coefficient and the wear rate show a decreasing trend. Among them, the friction coefficient decreases from 0.33 to 0.19, and the wear rate decreases from 2.28×10 -5 mm 3 ·N -1 ·m -1 to 1.95×10 -5 mm 3 ·N -1 ·m -1 .

[0091] Figure 12 This is the friction coefficient and wear rate diagram of the BMG / graphite layered composite prepared in Example 3 of the present invention at different frequencies. Figure 12 In which, (a) is the friction coefficient diagram and (b) is the wear rate diagram. As Figure 12 shown, it can be seen that at different frequencies, the friction coefficient of the material can be maintained in the range of 0.19 - 0.33, and the wear rate is maintained at 1.94×10 -5 mm 3 ·N -1 ·m -1~2.38×10 -5 mm 3 ·N -1 ·m -1 In the range, relatively speaking, the influence of the sliding frequency on the friction coefficient and wear rate of the material is slightly higher than that of the load on the friction coefficient and wear rate of the material. Generally speaking, the influence on the tribological properties of the material is not obvious.

[0092] Figure 13 Figure of the friction coefficient of the BMG / graphite laminated composite material prepared in Example 3 of the present invention under different loads and sliding frequencies, Figure 13 where (a) is different sliding frequencies and (b) is different loads. As Figure 13 shown, it can be seen that after a short running-in period, the friction coefficient of the composite material can reach a relatively stable state. As the frequency increases, the running-in period shortens, and a stable graphite lubricating film and transfer film can be quickly formed on the friction surface, thus achieving effective lubrication.

[0093] In addition, the tribological properties of the designed BMG / graphite laminated composite material under the conditions of 4 MPa, 20 Hz, a running time of 210 min, and a total stroke of 500 m were further investigated. Figure 14 Figure of the friction coefficient curve and three-dimensional morphology of the wear scar of the BMG / graphite laminated composite material in Example 3 of the present invention under the conditions of 4 MPa, 20 Hz, and a stroke of 500 m, Figure 14 where (a) is the friction coefficient curve figure and (b) is the three-dimensional morphology figure of the wear scar. As Figure 14 shown, it can be seen that the composite material has a stable friction coefficient and a low wear rate under a long stroke: the average friction coefficient is 0.21, and the wear rate is 1.51×10 -5 mm 3 ·N -1 ·m -1 , and the wear scar depth is 60.8 μm.

[0094] Figure 15 Wear scar morphology of the BMG / graphite laminated composite material in Example 3 of the present invention under the conditions of 4 MPa, 20 Hz and 2 MPa, 20 Hz, Figure 15 where (a) is 4 MPa, 20 Hz, (b) is 2 MPa, 20 Hz, and (c) is the relevant wear track figure of 2 MPa, 20 Hz. As Figure 15 shown, it can be seen that the wear scar morphology of the material at different frequencies is similar: the friction surface is smooth, almost no ploughing grooves and wear debris can be observed, and the friction surface is covered with a friction film distributed discretely. In addition, part of the lubricant in the graphite layer is continuously dragged and transferred to the friction surface under the action of the friction shear stress, forming a lubricating film with a uniform distribution on the friction contact surface. Among them, Figure 15The EDS atomic percentage content at the marked position in Figure (c) is shown in Table 1. The oxygen content on the friction film accounts for 50.72 at% ( Figure 15 in Figure (c) of Figure 15 "1"), indicating that the spalled wear debris is rolled and re-adhered to the friction contact surface during the friction process to form a hard friction film, which can improve the friction surface state of the composite material. In addition, from the component analysis of "2" on the friction surface, it can be seen that an oxide film with an oxygen content of 28.79 at% is formed on the friction surface. As mentioned above, during the friction process, the formation of a high-hardness oxide layer on the surface can resist the plowing damage of hard wear debris, thereby improving the wear resistance of the material.

[0095] Table 1 is Figure 15 the EDS atomic percentage content (at%) at the marked position in Figure (c) of

[0096] Element C O Cu Zr Al Ag 1 (at%) 14.17 50.72 12.39 16.89 2.86 2.98 2 (at%) 22.73 28.79 17.66 23.02 3.83 3.97

[0097] Figure 16 the wear scar morphology and EDS spectrum of the mating block BMG of the present invention, Figure 16 in which (a) is the wear scar morphology and (b) is the EDS spectrum. As Figure 16 shown, the mating block BMG and the BMG / graphite laminated composite material prepared in Example 3 are rubbed against each other. During the friction process, the graphite phase is transferred to the surface of the mating BMG to form a graphite transfer film. The presence of the graphite lubricating film and the transfer film on the friction surface can effectively reduce the friction coefficient and wear rate. The atomic percentage content of each element in the EDS spectrum is shown in Table 2.

[0098] Table 2 The atomic percentage content (at%) of each element in the EDS spectrum

[0099] Element C O Cu Zr Al Ag Content (at%) 22.34 24.20 19.55 25.21 4..13 4.57

[0100] Figure 17 is the enlarged view of the wear scar of the BMG / graphite laminated composite material of Example 1 of the present invention, Figure 17 in which (b) is the enlarged view of the framed part in (a). Figure 18 is for the present invention Figure 17 the surface distribution map of the elements in Figure (b) of Figure 18 in which a is the C element, b is the Zr element, c is the Cu element, d is the Ag element, e is the Al element, and f is the O element. As Figure 17 and Figure 18 shown, from the enlarged view of the wear scar microstructure, it can be seen that the graphite laminated structure is relatively intact after friction, and there are no cracks or holes at the interface between the graphite and the alloy two phases. A large amount of wear debris is accumulated in the microstructure where the graphite is located. During the friction slip process, the debris can escape from the contact surface and be captured by the regular surface texture, thereby reducing the plowing damage of the wear debris to the friction surface.

[0101] It should be noted that when the present invention involves numerical ranges, it should be understood that both endpoints of each numerical range and any value between the two endpoints can be selected. Since the adopted step methods are the same as those in the embodiments, in order to prevent redundancy, the present invention describes preferred embodiments. Although the preferred embodiments of the present invention have been described, those skilled in the art can make additional changes and modifications to these embodiments once they know the basic creative concept. Therefore, the appended claims are intended to be construed as including the preferred embodiments and all changes and modifications falling within the scope of the present invention.

[0102] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention is also intended to include these modifications and variations.

Claims

1. A method for preparing a metallic glass / graphite composite material with a mineral bridge structure, characterized in that: The following steps are involved: A plurality of graphite sheets are etched by laser processing to form a plurality of evenly distributed openings on each graphite sheet to obtain a plurality of graphite sheet layers; A plurality of graphite sheets are evenly arranged along the thickness direction and then fixed to form a precursor, a metallic glass matrix is ​​melted and injected onto the precursor for rapid cooling and casting, so that the metallic glass matrix is ​​suction-casted to fill all graphite sheets and all openings, a metallic glass layer is suction-casted on the surface of each graphite sheet, and the graphite sheets form a mineral bridge structure between all metallic glass layers to obtain a metallic glass / graphite composite material.

2. The method for preparing the metallic glass / graphite composite material with a mineral bridge structure according to claim 1, characterized in that: The interlayer spacing between adjacent graphite sheets is 0.2 mm to 2 mm.

3. The method for preparing the metallic glass / graphite composite material with a mineral bridge structure according to claim 1, characterized in that: The thickness ratio of the metallic glass layer to the graphite sheet layer is 2 to 40:

1.

4. The method for preparing the metallic glass / graphite composite material with a mineral bridge structure according to claim 1, characterized in that: The thickness of the metallic glass layer is 0.2 mm to 2 mm, and the thickness of the graphite sheet layer is 0.05 mm to 0.5 mm.

5. The method for preparing the metallic glass / graphite composite material with a mineral bridge structure according to claim 1, characterized in that: The open hole density on each graphite sheet is 5% to 80%.

6. The method for preparing the metallic glass / graphite composite material with a mineral bridge structure according to claim 1, characterized in that: The pore diameter of the opening is 100 μm to 1000 μm.

7. The method for preparing the metallic glass / graphite composite material with a mineral bridge structure according to claim 1, characterized in that: The wavelength of laser processing is 355nm, the pulse frequency is 20KHz~40KHz, the power is 5W~10W, and the scanning speed is 150mm / s~200mm / s.

8. The method for preparing the metallic glass / graphite composite material with a mineral bridge structure according to claim 1, characterized in that: After the rapid cooling casting is completed, the surface of the metallic glass / graphite composite material is polished until the surface roughness is less than 0.1 μm.

9. The method for preparing the metallic glass / graphite composite material with a mineral bridge structure according to claim 1, characterized in that: The metallic glass matrix is ​​Cu 36 Zr 48 Ag8Al8.

10. A metallic glass / graphite composite material prepared by the preparation method according to any one of claims 1 to 9.

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