A modular metal matrix composite material and a manufacturing method thereof

Abstract

A modular metal matrix composite material and a manufacturing method thereof. The modular metal matrix composite material of the present invention is formed by explosive bonding of functionalized modules and a matrix material; the number of functionalized modules is 3 to 10, and the composition of the functionalized modules varies in a gradient manner in the working direction of the modular metal matrix composite material. The modular metal matrix composite material of the present invention forms a modular metal matrix composite material with special functions by designing functional modules and combining the functionalized modules by certain means. The modular metal matrix composite material prepared by the present invention can realize arbitrary design of different functional characteristics of the core and the surface layer, and meet different service conditions.

Description

Technical Field

[0001] The present invention belongs to the technical field of manufacturing high-performance metal matrix composites, and particularly relates to a modular metal matrix composite and a manufacturing method thereof. Background Art

[0002] A metal matrix composite is a composite material artificially combined with a metal and its alloy as the matrix and one or several metal or non-metal reinforcing phases. Most of its reinforcing materials are inorganic non-metals, such as ceramics, carbon, graphite, boron, etc., and metal wires can also be used. Its characteristics in mechanics are relatively high transverse and shear strengths, good comprehensive mechanical properties such as toughness and fatigue, and at the same time, it also has advantages such as heat conduction, electricity conduction, wear resistance, small thermal expansion coefficient, good damping property, non-absorbing moisture, non-aging, and pollution-free.

[0003] The typical service conditions of metal matrix composites are in the field of friction and wear of materials. When metal matrix composites are used as current-carrying friction pairs and are widely applied in fields such as the pantograph-catenary system of rail transit, the armature / rail system of electromagnetic railguns, microelectronics and electrical control systems, aerospace space conductive rotary joint systems, moving / stationary contacts of high-voltage switches, etc., the current-carrying friction pairs often face situations such as multiple fields, multiple environments, and multiple atmospheres. Its service characteristics are that good frictional contact and electrical contact must be maintained simultaneously under harsh conditions such as high temperature, high pressure, and strong current. The harsh service environment requires that the current-carrying friction pair material not only has traditional room-temperature mechanical and conduction properties, but also has multiple properties such as good high-temperature mechanics, anti-electro-erosion, and wear resistance.

[0004] When metal matrix composites are used as wear-resistant parts, there is a huge demand for wear-resistant parts in fields such as mining machinery, coal mining and transportation, construction machinery, agricultural machinery, building materials, power machinery, and railway transportation. In industrialized countries, the losses caused by friction and wear are as high as 5% - 7% of GDP. For typical wear-resistant materials such as high manganese steel, medium / low alloy wear-resistant steel, chromium molybdenum silicon manganese steel and other traditional wear-resistant steels, after years of research, their wear resistance has approached the limit of traditional materials. How to further improve the wear resistance of materials is of great significance to the national economy.

[0005] Material surface treatment is a process method of artificially forming a surface layer with different mechanical, physical, and chemical properties from the matrix on the surface of the matrix material. The purpose of surface treatment is to meet the requirements of corrosion resistance, wear resistance, decoration, or other special functions of the product. Common surface treatment methods for metal materials include mechanical grinding, surface heat treatment, surface spraying, chemical / physical vapor deposition, electroplating, electroless plating, etc.

[0006] However, most of the surface treatment methods of the above processes are layer-by-layer deposition at the molecular scale, and the thickness of the prepared surface coating is limited. In addition, due to limitations such as equipment and site, the area of the prepared coating is usually small. With the complication and harshness of the service environment of metal materials, the above methods are gradually difficult to meet the coating requirements.

[0007] For example, current-carrying friction pairs are widely used in rail transit pantograph-catenary systems, electromagnetic railgun armature / rail systems, microelectronics and electrical control systems, aerospace space conductive rotary joint systems, high-voltage switch moving / static contacts and other fields. Current-carrying friction pairs often face multiple fields, multiple environments, multiple atmospheres, etc. Their service characteristics are that they must maintain good frictional contact and electrical contact simultaneously under harsh conditions such as high temperature, high pressure, and strong current. The harsh service environment requires that the current-carrying friction pair material not only has traditional room-temperature mechanical and conduction properties, but also has multiple properties such as good high-temperature mechanics, anti-electroerosion, and wear resistance.

[0008] An ideal current-carrying friction pair material has good electrical and thermal conductivity inside the material, while having good anti-electroerosion, friction resistance and other properties on the surface layer.

[0009] Conventional surface treatment technologies include technologies such as cold / hot spraying, plasma spraying, chemical vapor deposition, electroless plating, etc. Most of the principles are layer-by-layer deposition at the molecular scale, and the thickness of the prepared surface coating is limited. In addition, due to limitations such as process, equipment and site, the area of the prepared coating is usually small and cannot meet the harsh working conditions and large-scale service requirements of tracks. Summary of the Invention

[0010] The purpose of the present invention is to provide a modular metal matrix composite material and its manufacturing method. By designing the functional modules of the material and then combining the functional modules by certain means, a metal matrix composite material with special functions is formed to overcome the problem that a friction material in the prior art cannot simultaneously have multiple properties such as good high-temperature mechanics, anti-electroerosion, and wear resistance.

[0011] In order to achieve the above purpose, the present invention provides the following technical solutions:

[0012] A modular metal matrix composite material, wherein the modular metal matrix composite material is formed by explosive bonding of functional modules and a matrix material; the number of the functional modules is 3 to 10, and the composition of the functional modules changes in a gradient along the working direction of the modular metal matrix composite material.

[0013] The present invention also provides a manufacturing method of the above modular metal matrix composite material, and the preparation method includes the following steps:

[0014] (1) Prepare functional modules;

[0015] (2) Compound the functional module with the matrix material by explosive welding.

[0016] Advantages:

[0017] The present invention provides a modular metal matrix composite material and a manufacturing method thereof. By designing the functional modules of the material and combining the functional modules by certain means, a modular metal matrix composite material with special functions is formed. The modular metal matrix composite material prepared by the present invention can realize arbitrary design of different functional characteristics of the core and the surface layer, and meet different service conditions. Description of the Drawings

[0018] Figure 1 It is a top view of the modular metal matrix composite material;

[0019] Figure 2 It is a schematic diagram of module assembly;

[0020] Figure 3 It is a schematic diagram of a current-carrying friction and wear test;

[0021] Wherein: 1 - functional module; 2 - matrix material; 3 - counter material. Detailed Embodiment

[0022] The surface treatment technology in the prior art is to prepare a coating on the surface of the matrix material, and this coating plays a role in strengthening or special functions. Conventional surface treatment technologies include technologies such as cold / hot spraying, plasma spraying, vapor deposition, electroless plating, etc. Most of the principles are layer-by-layer deposition at the molecular scale, and the thickness of the prepared surface coating is limited. In addition, due to limitations such as process, equipment, and site, the prepared coating usually has a small area and cannot meet the harsh service conditions of tracks and other large-scale service requirements.

[0023] The solution proposed in the present invention adopts explosive forming, which uses the energy generated by explosive detonation or high-speed impact, acts on the workpiece in the form of shock waves, and compacts and sinters powders into a dense body under transient high temperature and high pressure. It has the advantages of short time, high pressure, and avoiding grain coarsening of materials caused by high-temperature heating. At the same time, since there is no equipment limitation, the sample size prepared by explosive forming can be infinitely large and the composition can be adjusted arbitrarily.

[0024] The core idea of the present invention is to design and prepare multiple functional modules 1 with special functions according to specific service performance requirements, and then compound one or more functional modules on the surface of the matrix material 2 by certain preparation means (typical means such as explosive welding), as Figure 1 shown.

[0025] As an embodiment of the present invention, the modular metal matrix composite is formed by explosive welding of functional modules and a matrix material; the number of functional modules is 3 to 10 (for example, it can be 3, 4, 5, 6, 7, 8, 9, 10), and the composition of the functional modules varies in a gradient along the working direction of the modular metal matrix composite. Preferably, the number of functional modules is 3 to 6.

[0026] As an embodiment of the present invention, the functional module is made of wear-resistant material. Preferably, the functional module is made of current-carrying friction material; more preferably, the current-carrying friction material is composed of heat-resistant material, wear-resistant and / or corrosion-resistant material. A certain proportion of mixed powder (one or more of Cu, W, Cr, ceramic particles, carbon fiber, carbon nanotube, graphene) is made into a functional module according to the service performance requirements, and then connected to the matrix material through an explosion welding process for compounding. In the present invention, there is no specific limitation on the particle size of the mixed powder, as long as it can be formed into a bulk material through powder metallurgy or other processes. For example, powder particle sizes of 10 nm to 500 μm commonly used in the metallurgical field can meet the requirements.

[0027] The main content of the preparation of the modular metal matrix composite of the present invention includes two major steps, namely modular design and module assembly. In the present invention, bulk modules are first made, and then explosive welding is carried out. The role of explosive welding is only to connect the modules to the substrate. The preparation of the modular metal matrix composite of the present invention is specifically as follows:

[0028] (I) Modular design:

[0029] Taking the current-carrying friction service environment as an example, an ideal current-carrying friction material has good electrical and thermal conductivity inside the material (a typical material is Cu-Cr alloy), while the surface significantly improves the anti-electroerosion and wear resistance on the basis of sacrificing a part of the conduction performance (a typical material is Cu-W alloy). Therefore, functional modules of a certain proportion of Cu-W alloy can be designed, and the ratio of Cu-W can be adjusted according to the service environment requirements. In the Cu-W alloy, as the proportion of W increases, the electrical conductivity gradually decreases, and the friction resistance and anti-electroerosion performance gradually increase. In the case of a lower current, the degree of electroerosion is lower, and 50Cu-50W (50 is the mass fraction, that is, 50 wt%, the same below) can be used. In the case of a higher current, the electroerosion intensifies, and a 20Cu-80W alloy with a higher W content is used to effectively resist damage. The Cu-W alloy functional module can be prepared by processes such as powder metallurgy or infiltration.

[0030] This module can be arbitrarily designed according to service requirements. For example, since carbon materials (carbon fiber, carbon nanotube, etc.) have good self-lubricating properties, carbon materials can also be added as a lubricating phase to this module to further improve the friction and wear performance. The following is a specific description of the gradient module.

[0031] The gradient in the present invention mainly refers to the gradient change of the composition of the composite material in the horizontal direction. Specifically, the horizontal gradient refers to the gradient change of the components of different modules on the material surface, that is, the change of the material composition in the direction parallel to the flat plate ( Figure 1 the composition of A - B - C changes gradually). A typical example is as follows: Suppose the friction starts from A and proceeds in the direction of C. A is in the initial stage of friction, belonging to the running - in stage, and the friction to be overcome is relatively large. Therefore, the composition of A is 30% carbon fiber and 70% copper powder. As the friction progresses, it gradually enters the stable stage, and the friction force gradually decreases. The compositions of B and C are 20% carbon fiber and 80% copper powder, 10% carbon fiber and 90% copper powder respectively.

[0032] The gradient change of the horizontal gradient is selected according to the actual service requirements of the material and combined with the difficulty of preparation, and is not limited to the form exemplified above. It can be understood that too large a difference in the component content between adjacent modules will affect the service performance of the material, and too small a difference in the component content between adjacent modules will increase the preparation difficulty of the material.

[0033] Similarly, a similar functionalized module can also be prepared on the surface of wear - resistant steel.

[0034] In the present invention, the components of the module can be arbitrarily designed according to the service requirements, that is, the module can be understood as a copper - based composite material with copper or copper alloy as the matrix and particles, fibers, etc. as the reinforcing phase. At present, the modules (copper - based composite materials) prepared by the present team include those with copper or Cu - Cr alloy as the matrix and one or several of ceramic particles (including but not limited to Al2O3, TiB2, MgO, SiC, etc.), carbon fibers, carbon nanotubes, silicon carbide whiskers, etc. as the reinforcing phase.

[0035] In a specific embodiment of the present invention, the functionalized module is prepared by powder metallurgy process. Specifically, it is obtained by compacting and sintering the mixed powder. The pressure for compaction is 100 - 500 MPa (such as 100 MPa, 150 MPa, 200 MPa, 250 MPa, 300 MPa, 350 MPa, 400 MPa, 450 MPa, 500 MPa), and the sintering temperature is 750 - 950 °C (such as 750 °C, 790 °C, 800 °C, 820 °C, 8400 °C, 850 °C, 870 °C, 900 °C, 930 °C, 950 °C).

[0036] It can be understood that the composite material prepared with copper or copper alloy as the matrix is mainly used as a conductive and heat - conductive material. And through the method provided by the present invention, composite materials with other functions can also be obtained, such as corrosion - resistant materials, wear - resistant materials, etc.

[0037] (II) Module Assembly

[0038] After the functional module is prepared by processes such as powder metallurgy and liquid phase infiltration, the module is compounded on the surface of the matrix material through an explosion cladding process to form a metal matrix composite material with a functional module on the surface layer, that is, a modular metal matrix composite material.

[0039] The matrix material is selected according to the actual use conditions: (1) In the case of electrical and thermal conductivity, the matrix material is pure copper or copper alloy (including but not limited to copper-chromium alloy, copper-nickel-silicon, copper-iron, copper-magnesium, copper-silver, etc.); (2) When used as a structural part or wear-resistant part, the matrix material can be steel (including but not limited to high manganese steel, medium and low alloy wear-resistant steel, chromium-molybdenum-silicon-manganese steel, etc.).

[0040] The modular concept proposed in the present invention is not limited to a specific occasion or a specific matrix, but rather this concept can be applied to a variety of materials. As for the thickness of the matrix material, it can also be adjusted arbitrarily according to the use conditions and does not require special limitation. However, considering the process requirements of explosion welding, if the matrix material is too thin, it may be unfavorable for explosion forming (as shown in the following literature), but it can be not regarded as the thickness limitation of the metal matrix.

[0041] In a specific embodiment of the present invention, the explosion welding is as follows: The functional modules are sequentially laid on the surface of the matrix material, a cover plate is covered above the functional modules and explosives are laid, and then the explosives are detonated; Preferably, the explosives are ammonium nitrate explosives, and the density of the explosives is 0.8 - 1.0 g / cm 3 (such as 0.8 g / cm 3 、0.82 g / cm 3 、0.84 g / cm 3 、0.86 g / cm 3 、0.86 g / cm 3 、0.9 g / cm 3 、0.92 g / cm 3 、0.94 g / cm 3 、0.96 g / cm 3 、0.98 g / cm 3 、1.0 g / cm 3 ). The detonation velocity of the explosion welding is 3.2 - 3.4×10 3 m / s (such as 3.2×10 3 m / s, 3.22×10 3 m / s, 3.25×10 3 m / s, 3.3×10 3 m / s, 3.32×10 3 m / s, 3.35×10 3 m / s, 3.38×10 3 m / s, 3.4×10 3m / s). The thickness of the explosive for explosion welding is 10 - 30 mm (for example, 10 mm, 15 mm, 20 mm, 25 mm, 30 mm).

[0042] Before compounding, the requirements for the matrix material are as follows: The surface is required to be flat as a whole. Any plane obtained by conventional machining means can be used, and there is no special roughness requirement, or rather, the requirement is relatively low. If there are impurities or oxide scales on the surface, they should be removed to avoid affecting the welding quality.

[0043] The following further elaborates on the modular metal matrix composite of the present invention in conjunction with specific embodiments.

[0044] Example 1

[0045] This example provides a horizontal gradient metal matrix composite based on carbon fiber / copper, and its preparation method is as follows:

[0046] 1) Prepare functional modules

[0047] Using copper powder (200 mesh) and carbon fiber (300 mesh) powder as raw materials, uniformly mix them to obtain a mixed powder. The volume ratios of the mixed powder are carbon fiber - copper powder 3:7, 2:8, and 1:9 respectively. They are denoted as mixed powder A1, mixed powder B1, and mixed powder C1 respectively.

[0048] Press each mixed powder into a blank by die pressing (the pressing pressure is 400 MPa), and then sinter it into a sintered blank (the sintering temperature is about 900 °C), finally obtaining functional modules A1, B1, and C1. That is, functional modules A1, B1, and C1 are carbon fiber-reinforced copper matrix composites with carbon fiber volume fractions of 30%, 20%, and 10% respectively.

[0049] 2) Module assembly and compounding

[0050] Lay three functional modules 1, specifically functional module A1, functional module B1, and functional module C1, in sequence on the surface of the matrix material 2 (Cu - Cr alloy plate), as Figure 2 shown.

[0051] After laying, cover a 5 - mm - thick copper plate on top of all functional modules as a cover plate for laying explosives, and remove the copper plate by machining after explosion. The explosive used is No. 2 rock ammonium nitrate, with an explosive density of 0.80 g / cm 3 , detonation velocity of 3.2×10 3m / s, with a drug thickness of 20 mm. Under the action of the explosion impact force, the cover plate further compacts and sinters the module and the substrate under high temperature and high pressure into a dense entity. Finally, the cover plate is removed by a gantry milling machine to expose the functionalized module. During the experiment, it was found that the thickness of the cover plate had little effect on the test, so generally there is no need to control the thickness of the cover plate.

[0052] The modular metal matrix composite material obtained above was tested by a current-carrying friction and wear test. The counter-material 3 was aluminum alloy, and the sliding friction was from the functionalized module A1 to the functionalized module C1 ( Figure 3 as shown, where the direction indicated by the arrow is the movement direction, that is, the working direction of the modular metal matrix composite material). The functionalized module A1 is in the initial stage of friction, belonging to the running-in stage, and the friction to be overcome is relatively large. Therefore, the carbon content in the functionalized module A1 is relatively high to provide a better lubrication effect. As the friction progresses, it gradually enters the stable stage, and the friction force gradually decreases. Therefore, the carbon content in the functionalized module B1 and the functionalized module C1 gradually decreases, and the copper content increases to increase the electrical conductivity. The specific process is as follows: A pin-on-disk rotational friction and wear experiment was carried out on the material using a self-made reciprocating friction and wear testing machine. The pin specimen was the research material with a size of φ6.3 mm × 15 mm. The friction pair material was aluminum alloy (i.e., the counter-material) with a size of φ50 mm × 8 mm. The linear velocity of the friction and wear experiment was 20 m / s, and the load was 30 N. Each sample was subjected to 3 parallel experiments, and the average value was taken. The test results show that for the metal matrix composite material prepared in this embodiment, under the current experimental conditions, the friction coefficient is about 0.20, and the wear rate is 1.48×10 -6 mg / m, and the current-carrying efficiency ≥ 80%.

[0053] Example 2

[0054] The modular metal matrix composite material of this embodiment is different from that of Example 1 in that: there are 4 functionalized modules, namely functionalized module A2, functionalized module B2, functionalized module C2, and functionalized module D2. The carbon fiber contents in the 4 functionalized modules are 3:7, 2:8, 1:9, and 0:10 respectively.

[0055] Using the explosion composite process in Example 1, the above 4 functional modules were combined with the matrix material Cu-Cr alloy plate to obtain a modular metal matrix composite material.

[0056] Using the method in Example 1 for testing, the results show that for the modular metal matrix composite material of this embodiment, under the current experimental conditions, the friction coefficient is about 0.21, and the wear rate is 1.52×10 -6 mg / m, and the current-carrying efficiency ≥ 78%.

[0057] Example 3

[0058] The modular metal matrix composite material of this embodiment is different from that of Embodiment 1 in that the parameters of the explosive welding process are different. Specifically, the explosive density is 0.90 g / cm 3 .

[0059] Using the method in Embodiment 1 for testing, the results show that the modular metal matrix composite material of this embodiment has a friction coefficient of about 0.20 and a wear rate of 1.49×10 -6 mg / m under the current experimental conditions, and the current-carrying efficiency is ≥80%.

[0060] Embodiment 4

[0061] The modular metal matrix composite material of this embodiment is different from that of Embodiment 1 in that the parameters of the explosive welding process are different. Specifically, the detonation velocity is 3.4×10 3 m / s.

[0062] Using the method in Embodiment 1 for testing, the results show that the modular metal matrix composite material of this embodiment has a friction coefficient of about 0.21 and a wear rate of 1.47×10 -6 mg / m under the current experimental conditions, and the current-carrying efficiency is ≥81%.

[0063] Embodiment 5

[0064] The modular metal matrix composite material of this embodiment is different from that of Embodiment 1 in that the parameters of the explosive welding process are different. Specifically, the explosive thickness is 25 mm.

[0065] Using the method in Embodiment 1 for testing, the results show that the modular metal matrix composite material of this embodiment has a friction coefficient of about 0.19 and a wear rate of 1.48×10 -6 mg / m under the current experimental conditions, and the current-carrying efficiency is ≥80%.

[0066] Control Example 1

[0067] As a control, a Cu-Cr alloy plate without explosive welding in Embodiment 1 was directly used for the current-carrying friction and wear test. Under the same experimental conditions as in Embodiment 1, the friction coefficient was about 0.41, the wear rate was 3.69×10 -6 mg / m, and the current-carrying efficiency was about 65%.

[0068] From the above embodiments and comparative examples, it can be seen that by modulating the surface of the Cu-Cr alloy plate through modular design, the current-carrying friction performance is significantly improved. Under the same experimental conditions, the friction coefficient is reduced by about 50%, the wear rate is reduced by about 60%, and the current-carrying efficiency is increased by about 15%.

Claims

1. A modular metal matrix composite material, characterized in that, The modular metal matrix composite is formed by explosive cladding of functionalized modules and a matrix material; the number of the functionalized modules is 3, and the composition of the functionalized modules varies in a gradient along the working direction of the modular metal matrix composite; The functionalized module is made of a current-carrying friction material; the current-carrying friction material is composed of a heat-resistant material and a wear-resistant and / or corrosion-resistant material; the functionalized module is prepared by powder metallurgy or infiltration process; The three functionalized modules are sequentially prepared from carbon fiber and copper powder with a volume ratio of 3:7, 2:8, and 1:9 as raw materials.

2. The manufacturing method of the modular metal matrix composite material according to claim 1, characterized in that, The preparation method includes the following steps: (1) Prepare the functionalized module; (2) Composite the functionalized module and the matrix material by explosion welding.

3. The manufacturing method of the modular metal matrix composite material according to claim 2, characterized in that, In step (1), the functionalized module is prepared by powder metallurgy process. Specifically, it is obtained by pressing and sintering a mixed powder. The pressure of pressing is 100 - 500 MPa, and the temperature of sintering is 750 - 950 °C.

4. The manufacturing method of the modular metal matrix composite material according to claim 2, characterized in that In step (2), the explosion welding is as follows: the functional modules are sequentially laid on the surface of the matrix material, a cover plate is covered above the functional modules and explosives are laid, and then the explosives are detonated; the explosives are ammonium nitrate explosives, and the density of the explosives is 0.8-1.0 g / cm 3 .

5. The manufacturing method of the modular metal matrix composite material according to claim 4, characterized in that The detonation velocity of the explosion welding is 3.2 - 3.4×10 3 m / s.

6. The manufacturing method of the modular metal matrix composite material according to claim 4, characterized in that, The thickness of the explosive welding charge is 10 - 30 mm.

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