Liquid infiltration forming method of light metal three-dimensional communication material with high strength, high plasticity and high elastic modulus

Abstract

The invention discloses a liquid infiltration forming method of a light metal three-dimensional communication material with high strength, high plasticity and high elastic modulus, and belongs to the field of material processing and mechanical manufacturing. The invention aims to solve the problems of non-uniform reinforced phase structure components and insufficient interfacial strength and mechanical properties in a three-dimensional connected material prepared by a polyurethane foam dipping-sintering and melt infiltration combined method. The method comprises the following steps: 1, preparing a reticular reinforced phase and carrying out surface treatment; 2, smelting of matrix metal; 3, preheating the mold; and fourthly, infiltration forming is conducted. The method is used for liquid infiltration forming of the light metal three-dimensional communication material with high strength, high plasticity and high elastic modulus.

Description

Technical Field

[0001] The invention belongs to the field of material processing and mechanical manufacturing. Background Art

[0002] With the development of science and technology, the fields of aerospace, automobile, new energy, equipment manufacturing, etc. have increasingly higher requirements for material performance, especially high-speed rail brake discs, high-temperature bearings, engine cylinders, fuel tanks, etc., which require materials to have lightweight, high strength and toughness, and resistance to thermal shock.

[0003] At present, commonly used light alloys include aluminum alloy, titanium alloy, magnesium alloy, etc. Taking aluminum alloy as an example, this alloy has a low density, which is about 30% of the density of steel, and has excellent low-temperature performance, no low-temperature brittleness, and both strength and ductility increase simultaneously with the decrease of temperature. It has good machinability, formability, and weldability, and is a good low-temperature structural material. However, the use of a single type of alloy can only meet some indicators of the performance requirements of new equipment, and cannot overcome the shortcomings of this material performance. Take aluminum alloy fuel tanks as an example: on the one hand, cast aluminum alloys with excellent toughness and welding performance cannot meet the requirements of its high-temperature use environment, and the fuel tank material must meet the strength and toughness requirements under high temperature conditions; on the other hand, heat-resistant aluminum alloys are difficult to meet the welding performance requirements of fuel tank parts. At present, aluminum alloy fuel tanks are mainly formed by integral casting or split welding, and internal cooling structure design or external insulation coating and other methods are used to solve the problem of use in high-temperature environments. However, these process methods are relatively cumbersome, costly, occupy product space, and increase weight. For example, the design of the cooling device requires an increase in the thickness of the part. In order to overcome the performance disadvantages of a single material, people began to use metal matrix composites (MMCs) to make up for these defects and meet higher performance requirements.

[0004] For metal matrix composites, the selection of reinforcing phase is crucial. Ceramic materials (such as SiC, TiC, Al2O3, etc.) have the characteristics of high hardness, high modulus, high strength, low density, etc., and are a kind of reinforcing phase that is widely used in metal matrix composites. However, ceramic materials themselves are brittle materials. Compared with metal materials, they have poor plasticity, toughness, machinability, and low reliability. When loaded at room temperature, the plastic deformation is small, but fatigue fracture damage occurs within the elastic deformation range. In addition, the wettability between metal and ceramic is poor, and the difference in thermal expansion coefficient is large, which easily leads to unstable interface bonding, resulting in cracking. The above performance characteristics of ceramic materials make their application have great limitations, limiting their further development. Compared with ceramic materials, metal materials have higher plasticity and strength, good welding performance, which makes up for the defect of poor toughness of ceramic materials. In terms of structure, metal materials are easier to form than ceramic materials, the shape and size of the structure are easy to control, and the problem of poor wettability is avoided, thereby reducing the difficulty of material processing.

[0005] According to the different forms of reinforcement phase, metal matrix composites can be divided into: continuous fiber reinforced composites, discontinuous phase reinforced composites, layered composites, etc. Among them, the continuous long fiber reinforcement has a significant reinforcement effect on the matrix metal, but due to the directional arrangement of the fibers, its performance has obvious anisotropy, so it is difficult to manufacture and has high costs; discontinuous particles, whiskers, short fibers, etc. can reduce the difficulty and cost of manufacturing composites, and avoid the anisotropy of long fiber reinforcement phase; the reinforcement strength of layered composites is slightly lower than that of long fiber reinforcement, but in all directions of the reinforcement plane, the thin sheet reinforcement has an enhancement effect on strength and modulus.

[0006] In recent years, three-dimensional interconnected materials (also called three-dimensional network composite materials) have attracted widespread attention. Some scholars at home and abroad have conducted research and exploration on them and have achieved some research results. This special three-dimensional network topological structure makes each phase of the composite material isotropic. When the high-strength reinforcement skeleton and the matrix metal are subjected to external loads, they interact, constrain and enhance each other. The two phases are well combined, and have better friction and wear properties and mechanical properties than particle, whisker, and fiber reinforced composite materials; the continuity of the metal phase in three-dimensional space improves the toughness, thermal conductivity and electrical conductivity of the composite material.

[0007] In addition, the reinforcement phase of this material can be either a three-dimensional network structure or a planar porous mesh structure. Its preparation methods include traditional polyurethane foam impregnation-sintering, adding foaming agents and other methods, as well as advanced manufacturing methods such as additive manufacturing and three-dimensional weaving technology. At present, this composite material is mostly prepared by liquid infiltration forming, that is, pouring liquid or semi-solid metal into the mesh reinforcement phase, and obtaining the desired material after solidification. The above scheme can be used to prepare three-dimensional mesh porous structure composite materials with different volume fractions and different properties, which provides another new idea for the development of new materials.

[0008] At present, the method of combining polyurethane foam impregnation-sintering with melt infiltration is a commonly used process for preparing three-dimensional interconnected composite materials. However, the polyurethane foam impregnation-sintering process still has some problems when preparing the reinforcing phase. First, during the impregnation process, the distribution of the reinforcing phase is uneven and difficult to control; secondly, the pore size of the reinforcing phase after sintering is uneven, and unfavorable elements may remain. These will lead to insufficient liquid-solid interface bonding strength during the impregnation of the molten matrix metal, thereby affecting the mechanical properties of this material. Summary of the invention

[0009] The present invention aims to solve the problems of uneven reinforcing phase structure composition, insufficient interface strength and mechanical properties in three-dimensional interconnected materials prepared by a combination of polyurethane foam impregnation-sintering and melt infiltration, and further provide a liquid infiltration forming method for lightweight metal three-dimensional interconnected materials with high strength, high plasticity and high elastic modulus.

[0010] A liquid infiltration forming method for a lightweight metal three-dimensional interconnected material with high strength, high plasticity and high elastic modulus is carried out in the following steps:

[0011] 1. Preparation and surface treatment of network reinforcement phase:

[0012] The mesh alloy reinforcement is prepared by using additive manufacturing technology or three-dimensional weaving technology, and then the mesh alloy reinforcement is surface treated to obtain a pre-treated reinforcement;

[0013] 2. Melting of base metal:

[0014] At the melting temperature T1, the base metal ingot is heated and melted, and then a slag remover is added to remove impurities to obtain a liquid base metal;

[0015] 3. Preheating of mold:

[0016] The pretreated reinforcement is placed in a casting mold, and then preheated to a temperature T2 to obtain a mold with a temperature of T2;

[0017] 4. Melt Infiltration Forming:

[0018] The liquid matrix metal is poured into a mold at a temperature of T2 and infiltrated under pressure. After naturally cooling and solidifying at room temperature, it is taken out, thereby completing the liquid infiltration forming method of a lightweight metal three-dimensional interconnected material with high strength, high plasticity and high elastic modulus.

[0019] The beneficial effects of the present invention are:

[0020] 1. The special topological structure of the three-dimensional network composite material makes each phase of the composite material isotropic, and can constrain and reinforce each other when subjected to load, thereby improving the mechanical properties of the matrix metal (such as strength, elastic modulus, plasticity, etc.).

[0021] 2. The reinforcement phase uses metal materials, which can not only improve the elastic modulus and strength of the material, but also ensure good plasticity; at the same time, metal materials have good machinability, so the metal skeleton can be easily processed according to the shape of the parts.

[0022] 3. The metal skeleton in the present invention is obtained by additive manufacturing or three-dimensional weaving technology. Compared with traditional methods such as polyurethane foam impregnation-sintering, this method can avoid the problems of difficult control of reinforcement phase components, uneven distribution of local components, and uneven pore size after sintering to a certain extent.

[0023] 4. Liquid infiltration forming technology can realize the integration of material preparation and precision forming, with high interface strength, reducing the amount of subsequent machining, simplifying the process steps, and appropriately reducing costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram of the liquid infiltration forming method of the lightweight metal three-dimensional interconnected material with high strength, high plasticity and high elastic modulus of the present invention. DETAILED DESCRIPTION

[0025] Specific implementation method 1, combined with Figure 1 Specific description: This embodiment is a liquid infiltration forming method of a lightweight metal three-dimensional interconnected material with high strength, high plasticity and high elastic modulus, which is carried out in the following steps:

[0026] 1. Preparation and surface treatment of network reinforcement phase:

[0027] The mesh alloy reinforcement is prepared by using additive manufacturing technology or three-dimensional weaving technology, and then the mesh alloy reinforcement is surface treated to obtain a pre-treated reinforcement;

[0028] 2. Melting of base metal:

[0029] At the melting temperature T1, the base metal ingot is heated and melted, and then a slag remover is added to remove impurities to obtain a liquid base metal;

[0030] 3. Preheating of mold:

[0031] The pretreated reinforcement is placed in a casting mold, and then preheated to a temperature T2 to obtain a mold with a temperature of T2;

[0032] 4. Melt Infiltration Forming:

[0033] The liquid matrix metal is poured into a mold at a temperature of T2 and infiltrated under pressure. After naturally cooling and solidifying at room temperature, it is taken out, thereby completing the liquid infiltration forming method of a lightweight metal three-dimensional interconnected material with high strength, high plasticity and high elastic modulus.

[0034] In the present embodiment, during the casting process, the temperature of the mold is always maintained at T2; and during the solidification of the base metal, the mold is naturally cooled at room temperature.

[0035] The beneficial effects of this embodiment are:

[0036] 1. The special topological structure of the three-dimensional network composite material makes each phase of the composite material isotropic, and can constrain and reinforce each other when subjected to load, thereby improving the mechanical properties of the matrix metal (such as strength, elastic modulus, plasticity, etc.).

[0037] 2. The reinforcement phase uses metal materials, which can not only improve the elastic modulus and strength of the material, but also ensure good plasticity; at the same time, metal materials have good machinability, so the metal skeleton can be easily processed according to the shape of the parts.

[0038] 3. The metal skeleton in this embodiment is obtained by additive manufacturing or three-dimensional weaving technology. Compared with traditional methods such as polyurethane foam impregnation-sintering, this method can avoid problems such as difficult control of reinforcement phase components, uneven distribution of local components, and uneven pore size after sintering to a certain extent.

[0039] 4. Liquid infiltration forming technology can realize the integration of material preparation and precision forming, with high interface strength, reducing the amount of subsequent machining, simplifying the process steps, and appropriately reducing costs.

[0040] Specific implementation method 2: This implementation method is different from specific implementation method 1 in that the material of the mesh alloy reinforcement body in step 1 is a high melting point metal; the high melting point metal is a titanium alloy or a copper alloy. The rest is the same as specific implementation method 1.

[0041] Specific implementation method 3: This implementation method is different from specific implementation method 1 or 2 in that the pores in the mesh alloy reinforcement described in step 1 have a diameter of 2 mm to 5 mm. Other aspects are the same as specific implementation method 1 or 2.

[0042] Specific embodiment 4: This embodiment is different from specific embodiments 1 to 3 in that the thickness of the mesh alloy reinforcement described in step 1 is 0.5 mm to 2 mm. The rest is the same as specific embodiments 1 to 3.

[0043] Specific implementation method five: This implementation method is different from specific implementation methods one to four in that: the surface treatment described in step one is specifically carried out according to the following steps: soak the mesh alloy reinforcement in anhydrous ethanol for 1min to 2min, then take it out and place it in a mixed solution of HF and HNO3 for pickling for 2min to 4min, take it out again and rinse it with alcohol and water, and finally dry it naturally; the mixed solution of HF and HNO3 is a mixture of HF solution, HNO3 solution and water, the volume ratio of the HF solution to the HNO3 solution is 1: (3 to 5), the volume ratio of the HF solution to the water is 1: (9 to 10), the concentration of the HF solution is 0.4mol / L to 1mol / L, and the concentration of the HNO3 solution is 1.2mol / L to 3mol / L. The rest is the same as specific implementation methods one to four.

[0044] Specific implementation example 6: This implementation example is different from specific implementation examples 1 to 5 in that the base metal ingot in step 2 is made of a light metal, which is an aluminum alloy or a magnesium alloy. The rest is the same as specific implementation examples 1 to 5.

[0045] Specific embodiment 7: This embodiment is different from Specific embodiments 1 to 6 in that the slag remover in step 2 is NaNO3 or KNO3. The rest is the same as Specific embodiments 1 to 6.

[0046] Specific implementation eight: This implementation differs from specific implementations one to seven in that: in step three, T2 = (0.5-0.6) T1. The rest is the same as specific implementations one to seven.

[0047] Specific embodiment 9: This embodiment is different from specific embodiments 1 to 8 in that: the pressure infiltration in step 4 is specifically carried out according to the following steps: using a press machine, pressurized infiltration under air atmosphere and pressure of 300kN to 500kN, and the starting position of the press punch is just above the feeding port, the press punch moves downward during pressurization, and the liquid matrix metal is pressed into the die cavity, and the pressurization is stopped when the liquid matrix metal completely fills the die cavity. The rest is the same as specific embodiments 1 to 8.

[0048] Specific embodiment 10: This embodiment differs from specific embodiments 1 to 9 in that the inner wall of the tool used in step 2 to step 4 is coated with a ZnO coating. The rest is the same as specific embodiments 1 to 9.

[0049] The following examples are used to verify the beneficial effects of the present invention:

[0050] Embodiment 1:

[0051] A liquid infiltration forming method for a lightweight metal three-dimensional interconnected material with high strength, high plasticity and high elastic modulus is carried out in the following steps:

[0052] 1. Preparation and surface treatment of network reinforcement phase:

[0053] The mesh alloy reinforcement is prepared by using additive manufacturing technology or three-dimensional weaving technology, and then the mesh alloy reinforcement is surface treated to obtain a pre-treated reinforcement;

[0054] The material of the mesh alloy reinforcement is TA15;

[0055] The pores in the mesh alloy reinforcement have a pore diameter of 5 mm;

[0056] The thickness of the mesh alloy reinforcement is 1 mm;

[0057] 2. Melting of base metal:

[0058] Under the condition of a melting temperature of 750°C, a base metal ingot is placed in a crucible for heating and melting, and then a slag remover is added to remove impurities to obtain a liquid base metal;

[0059] The material of the base metal ingot is 5A06 aluminum alloy;

[0060] The deslagging agent is NaNO3;

[0061] 3. Preheating of mold:

[0062] The pretreated reinforcement is placed in a casting mold, and then preheated to a temperature of 400° C. to obtain a mold with a temperature of 400° C.;

[0063] 4. Melt Infiltration Forming:

[0064] Using a press, in an air atmosphere and a pressure of 500kN, the liquid matrix metal is poured into a mold at a temperature of 400°C for pressure infiltration, and the starting position of the press punch is directly above the feeding port. When pressurized, the press punch moves downward to press the liquid matrix metal into the mold cavity. When the liquid matrix metal completely fills the mold cavity, the pressurization is stopped. Finally, it is taken out after natural cooling and solidification at room temperature, thereby completing the liquid infiltration forming method of a lightweight metal three-dimensional interconnected material with high strength, high plasticity and high elastic modulus.

[0065] The surface treatment described in step one is specifically carried out according to the following steps: soaking the mesh alloy reinforcement in anhydrous ethanol for 1 minute, then taking it out and placing it in a mixed solution of HF and HNO3 for pickling for 2 minutes, taking it out again and rinsing it with alcohol and water, and finally drying it naturally; the mixed solution of HF and HNO3 is a mixture of HF solution, HNO3 solution and water, the volume ratio of the HF solution to the HNO3 solution is 1:3, the volume ratio of the HF solution to water is 1:10, the concentration of the HF solution is 0.4 mol / L, and the concentration of the HNO3 solution is 1.2 mol / L.

[0066] The crucible, casting mold and inner wall of the casting tool used in the process from step 2 to step 4 are coated with ZnO coating to prevent the liquid matrix metal from reacting with the inner wall and also facilitate demoulding.

[0067] The reinforcement metal of this embodiment uses TA15 titanium alloy. Adding this alloy to the 5A06 aluminum alloy matrix can improve the strength and elastic modulus of the material while ensuring good plasticity of the material. The TA15 reinforcement is obtained by additive manufacturing or three-dimensional weaving technology, which can avoid problems such as difficult control of reinforcement phase components, uneven distribution of local components, and uneven pore size after sintering. This composite material is prepared by liquid infiltration forming technology, which can realize the integration of material preparation and precision forming, has high interface strength, reduces the amount of subsequent mechanical processing, simplifies the process steps, and appropriately reduces costs.

Claims

1. A liquid infiltration forming method for a lightweight metal three-dimensional interconnected material with high strength, high plasticity and high elastic modulus, characterized in that It is carried out in the following steps:

1. Preparation and surface treatment of network reinforcement phase: The mesh alloy reinforcement is prepared by using additive manufacturing technology or three-dimensional weaving technology, and then the mesh alloy reinforcement is surface treated to obtain a pre-treated reinforcement; 2. Melting of base metal: At the melting temperature T1, the base metal ingot is heated and melted, and then a slag remover is added to remove impurities to obtain a liquid base metal; 3. Preheating of mold: The pretreated reinforcement is placed in a casting mold, and then preheated to a temperature T2 to obtain a mold with a temperature of T2; 4. Melt Infiltration Forming: The liquid matrix metal is poured into a mold at a temperature of T2 and infiltrated under pressure. After naturally cooling and solidifying at room temperature, it is taken out, thereby completing the liquid infiltration forming method of a lightweight metal three-dimensional interconnected material with high strength, high plasticity and high elastic modulus.

2. The method for liquid infiltration forming of a lightweight metal three-dimensional interconnected material with high strength, high plasticity and high elastic modulus according to claim 1, characterized in that The material of the mesh alloy reinforcement described in step 1 is a high melting point metal; the high melting point metal is a titanium alloy or a copper alloy.

3. The method for liquid infiltration forming of a lightweight metal three-dimensional interconnected material with high strength, high plasticity and high elastic modulus according to claim 1, characterized in that The pores in the mesh alloy reinforcement described in step 1 have a pore size of 2 mm to 5 mm.

4. The method for liquid infiltration forming of a lightweight metal three-dimensional interconnected material with high strength, high plasticity and high elastic modulus according to claim 1, characterized in that The thickness of the mesh alloy reinforcement described in step 1 is 0.5 mm to 2 mm.

5. The method for liquid infiltration forming of a lightweight metal three-dimensional interconnected material with high strength, high plasticity and high elastic modulus according to claim 1, characterized in that The surface treatment described in step one is specifically carried out according to the following steps: soaking the mesh alloy reinforcement in anhydrous ethanol for 1min to 2min, then taking it out and placing it in a mixed solution of HF and HNO3 for pickling for 2min to 4min, taking it out again and rinsing it with alcohol and water, and finally drying it naturally; the mixed solution of HF and HNO3 is a mixture of HF solution, HNO3 solution and water, the volume ratio of the HF solution to the HNO3 solution is 1: (3 to 5), the volume ratio of the HF solution to water is 1: (9 to 10), the concentration of the HF solution is 0.4mol / L to 1mol / L, and the concentration of the HNO3 solution is 1.2mol / L to 3mol / L.

6. The method for liquid infiltration forming of a lightweight metal three-dimensional interconnected material with high strength, high plasticity and high elastic modulus according to claim 1, characterized in that The material of the base metal ingot described in step 2 is a light metal; the light metal is an aluminum alloy or a magnesium alloy.

7. The method for liquid infiltration forming of a lightweight metal three-dimensional interconnected material with high strength, high plasticity and high elastic modulus according to claim 1, characterized in that The slag remover described in step 2 is NaNO3 or KNO3.

8. The method for liquid infiltration forming of a lightweight metal three-dimensional interconnected material with high strength, high plasticity and high elastic modulus according to claim 1, characterized in that In step 3, T2 = (0.5-0.6) T1.

9. The method for liquid infiltration forming of a lightweight metal three-dimensional interconnected material with high strength, high plasticity and high elastic modulus according to claim 1, characterized in that The pressure infiltration in step 4 is specifically carried out according to the following steps: using a press machine, pressure infiltration is carried out under air atmosphere and a pressure of 300kN to 500kN, and the starting position of the press punch is directly above the feeding port. When pressurizing, the press punch moves downward to press the liquid matrix metal into the mold cavity. When the liquid matrix metal completely fills the mold cavity, the pressurization is stopped.

10. The method for liquid infiltration forming of a lightweight metal three-dimensional interconnected material with high strength, high plasticity and high elastic modulus according to claim 1, characterized in that The inner walls of the tools used in the process from step 2 to step 4 are coated with ZnO coating.

Images