A gradient composite material and preparation method thereof

Abstract

The present invention relates to a gradient composite material and a preparation method thereof. The preparation method comprises the following steps: S1, selecting a substrate and at least two printing powder feeding materials; S2, respectively loading the at least two printing powder feeding materials into at least two powder feeding barrels and / or mixing the powders and loading the mixed powders into at least two powder feeding barrels; S3, loading the substrate into a laser printing device and fixing it in a working area, and performing inert gas purge on the working box of the laser printing device; S4, using high-speed laser powder feeding technology to perform 3D printing based on a preset printing path, linking or separately controlling different powder feeding barrels, and adjusting the powder feeding speeds of the different powder feeding barrels to achieve composition changes in different regions of the gradient composite material, while simultaneously adjusting the laser scanning power and laser movement speed to obtain a printed sample; S5, sequentially performing heat treatment and surface treatment on the printed sample to obtain a gradient composite material. This preparation method can meet the requirements for different compositions of composite materials during printing in different regions.

Description

Technical Field

[0001] The present invention belongs to the technical field of additive manufacturing, and in particular relates to a gradient composite material and a preparation method thereof. Background Art

[0002] Vacuum switches are highly reliable, environmentally friendly, and clean circuit protection devices. Contact materials, as core components, play a crucial role in their operation. Currently, in the field of medium- and high-voltage vacuum switches, CuCr is widely used as a contact material due to its excellent breaking, voltage resistance, resistance to welding, and high electrical and thermal conductivity.

[0003] In vacuum switches, when the Cr content is high (40-60%), the contact material exhibits high hardness and compressive strength, but the electrical and thermal conductivity will decrease. When the Cr content is low (10-30%), the electrical conductivity, thermal conductivity, and breaking performance of the contact are excellent, but the pressure resistance and arc erosion resistance of the high Cr content contact are reduced. The gradient contact sheet structure with functional partitioning can combine the advantages of high Cr content and low Cr content to achieve a high-performance contact structure. For example, in a transverse magnetic field contact, the internal contact part uses a low Cr content to improve the electrical and thermal conductivity, and the external part uses a high Cr content to improve the contact's pressure resistance and erosion resistance.

[0004] However, in the current industrial production process, due to the limitations of the preparation process, only contact materials with a single component in the working area, or composite materials with different components in the upper and lower layers, can be prepared. This cannot meet the requirements of vacuum switches in the design process for different components in different lateral working areas. Summary of the Invention

[0005] In order to solve the above problems existing in the prior art, the present invention provides a gradient composite material and a preparation method thereof. The technical problem to be solved by the present invention is achieved by the following technical solutions:

[0006] An embodiment of the present invention provides a method for preparing a gradient composite material, comprising the steps of:

[0007] S1. Select a substrate and select at least two printing powder feeding materials according to the composition of the gradient composite material;

[0008] S2. According to the composition and specific gravity of the gradient composite material, the at least two printing powder feeding materials are respectively loaded into at least two powder feeding buckets and / or mixed and loaded into at least two powder feeding buckets;

[0009] S3, loading the substrate into a laser printing device and fixing it in a working area, and performing inert gas purge on a working box of the laser printing device;

[0010] S4. Using high-speed laser powder feeding technology, 3D printing is performed based on a preset printing path. Different powder feeding barrels are linked or separately controlled according to the component proportion of the gradient composite material. The powder feeding speeds of the different powder feeding barrels are adjusted according to the component proportion of the gradient composite material and the powder feeding flow rate of the printing powder feeding material to achieve composition changes in different regions of the gradient composite material. The laser scanning power and laser movement speed are adjusted according to the proportion of different melting point components of the gradient composite material to obtain a printed sample.

[0011] S5. Performing heat treatment and surface treatment on the printed sample in sequence to obtain a gradient composite material.

[0012] In one embodiment of the present invention, when the gradient composite material is a gradient composite contact material, the at least two printing powder feeding materials include a first element powder, a second element powder and a trace element powder, the first element powder includes Cu powder, the second element powder includes one or more of Cr powder and W powder, and the trace element powder includes one or more of Bi powder and Te powder.

[0013] In one embodiment of the present invention, when the first element powder, the second element powder and the trace element powder are mixed,

[0014] The content of the Cu powder is 40-100%;

[0015] The mass ratio of the Cu powder to the Cr powder is 1:1-60%, the mass ratio of the Cu powder to the W powder is 1:1-60%, the mass ratio of the Cu powder to the Bi powder is 1:0.1-3%, and the mass ratio of the Cu powder to the Te powder is 1:0.1-3%.

[0016] In one embodiment of the present invention, when the at least two printing powder feeding materials include Cu powder, heat absorbing material powder is added to the Cu powder.

[0017] In one embodiment of the present invention, the mass of the endothermic material powder is less than or equal to 0.3% of the mass of the Cu powder;

[0018] The endothermic material powder includes one or more of ZrC, LaB6, and CrC.

[0019] In one embodiment of the present invention, step S2 includes:

[0020] According to the composition and proportion of the gradient composite material, different printing powder feeding materials are respectively loaded into the corresponding powder feeding barrels; or,

[0021] According to the composition and proportion of the gradient composite material, the at least two printing powder feeding materials are mixed in different mass proportions to obtain mixed powders in different regions of the gradient composite material; and the mixed powders in different regions are loaded into different powder feeding barrels.

[0022] In one embodiment of the present invention, the powder feeding speed of the powder feeding barrel is negatively correlated with the component specific gravity of the gradient composite material and negatively correlated with the powder feeding flow rate of the printing powder feeding material;

[0023] The laser scanning power is positively correlated with the proportion of the high melting point component, and the laser moving speed is negatively correlated with the laser scanning power.

[0024] In one embodiment of the present invention, the powder feeding air flow rate of the printing powder feeding material is 5-15 L / min, the powder feeding flow rate of the printing powder feeding material is 15s / 50g-23s / 50g, and the powder feeding speed of the powder feeding barrel is 0.1-2rap / min;

[0025] The laser scanning power is 3-10 kW, and the laser moving speed is 5-1000 cm / min.

[0026] In one embodiment of the present invention, the heat treatment includes solution heat treatment and aging heat treatment;

[0027] The solution heat treatment temperature is 800-1100°C and the temperature is kept for 1-4 hours;

[0028] The aging temperature of the aging heat treatment is 430-450° C., and the holding time is 3-5 hours.

[0029] Another embodiment of the present invention provides a gradient composite material prepared by the preparation method described in the above embodiment, wherein the gradient composite material has several regions with different compositions.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] 1. The preparation method of the present invention selects different printing powder feeding materials according to the composition of the gradient composite material, and loads them into different powder feeding barrels for 3D printing. During the printing process, the different powder feeding barrels are linked or controlled separately, and the composition changes in different areas of the gradient composite material are achieved by adjusting the powder feeding speed of the powder feeding barrels. The quality of the printing process is guaranteed by controlling the laser scanning power and laser movement speed, thereby realizing the requirements of different compositions of the composite material during the printing process in different areas.

[0032] 2. In the preparation method of the present invention, when the printing powder feeding material includes Cu powder, endothermic material powder is added to the Cu powder. The endothermic material powder can effectively improve the heat absorption efficiency during the copper alloy printing process, reduce printing defects, and improve product quality.

[0033] 3. The preparation method of the present invention can realize the requirements of different components of contact materials during the printing process in different areas, and prepare high-performance contact materials to meet the requirements of vacuum switches for different properties such as high conductivity, thermal conductivity, compressive strength, resistance to welding, and resistance to ablation. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 A schematic flow chart of a method for preparing a gradient composite material provided by an embodiment of the present invention;

[0035] Figure 2 A schematic structural diagram of a gradient composite contact material provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0036] The present invention will be further described in detail below with reference to specific examples, but the embodiments of the present invention are not limited thereto.

[0037] Example 1

[0038] See Figure 1 , Figure 1 A schematic flow chart of a method for preparing a gradient composite material provided by an embodiment of the present invention. The method for preparing the gradient composite material includes several processes: raw material preparation, powder mixing, loading, pre-printing treatment, laser printing, heat treatment, and surface treatment. Specifically, the steps include:

[0039] S1. Select a substrate and select at least two printing powder feeding materials according to the composition of the gradient composite material.

[0040] Specifically, the gradient composite material includes but is not limited to gradient composite contact material, gradient stainless steel material, gradient high-temperature Ni alloy material, and gradient high-temperature Ti alloy material.

[0041] When the gradient composite material is a transverse gradient composite contact material, the at least two printing powder feeding materials include a first element powder, a second element powder and a trace element powder, the first element powder includes Cu powder, the second element powder includes but is not limited to one or more of Cr powder and W powder, and the trace element powder includes one or more of Bi powder and Te powder.

[0042] In this embodiment, the performance of the contact material can be improved by adding trace element powder.

[0043] Furthermore, when the at least two printing powder feed materials include Cu powder, endothermic material powder is added to the Cu powder. The mass of the endothermic material powder is less than or equal to 0.3% of the mass of the Cu powder; the endothermic material powder includes one or more of ZrC, LaB6, and CrC.

[0044] In this embodiment, adding a small amount of heat-absorbing material to the copper powder can effectively improve the heat absorption efficiency during the copper alloy printing process, reduce printing defects, and improve product quality. As for Ti and Fe powders, since they have good heat absorption properties, no material needs to be added.

[0045] When the gradient composite material is a gradient stainless steel material, the at least two printing powder feeding materials include a first element powder and a second element powder, the first element powder includes Fe powder, and the second element powder includes but is not limited to one or more of Cr powder, Ni powder, Mo powder, Ti powder, Cu powder, and Nb powder.

[0046] When the gradient composite material is a gradient high-temperature Ni alloy material, the at least two printing powder feeding materials include a first element powder and a second element powder, the first element powder includes Ni powder, and the second element powder includes but is not limited to one or more of Cr powder, Co powder, Fe powder, W powder, Mo powder, Ti powder, Cu powder, and Nb powder.

[0047] When the gradient composite material is a gradient high-temperature Ti alloy material, the at least two printing powder feeding materials include a first element powder and a second element powder, the first element powder includes Ti powder, and the second element powder includes but is not limited to one or more of Cr powder, Mn powder, Fe powder, W powder, Al powder, Cu powder, Zr powder, and Sn powder.

[0048] Gradient composite materials are materials with multiple regions of varying composition. These regions can achieve multi-dimensional gradients, not limited to stacking them one above the other or distributing them laterally along the surface of the material. Gradient composites can also be applied to any shape. For example, stacking multiple regions of varying composition one above the other can achieve a longitudinal gradient distribution; distributing multiple regions of varying composition sequentially from one side of the material surface to the other can achieve a transverse gradient distribution; distributing multiple regions of varying composition from the center of the material surface to the outside can achieve a transverse gradient distribution, and so on.

[0049] Taking contact materials as an example, ordinary materials are mainly composed of CuCr materials, and the content of CuCr materials along the surface of the material remains unchanged. However, for gradient composite contact materials, the materials in each area have different contents of Cu and Cr. Figure 2 As shown, Figure 2 A schematic structural diagram of a gradient composite contact material provided by an embodiment of the present invention is shown. Figure 2 In the embodiment, the gradient composite contact material is divided into two regions along its surface from the center to the outer edge, the outer edge region surrounds the middle region, the Cr content in the CuCr material in the middle region is 1-30%, and the Cr content in the CuCr material in the outer edge region is 30-60%.

[0050] Specifically, the particle diameter of the printing powder feeding material is 5-300 μm, and the requirements for the powder particle size are relatively low.

[0051] Specifically, the substrate can be selected according to the printing material, and the substrate can have different shapes such as sheet material, rod material, etc. The material of the substrate can be steel, Cu, etc. For example, pure Cu or Cu alloy is selected as the substrate for the gradient composite contact material, such as Figure 2 shown.

[0052] Furthermore, when a copper substrate is selected, a black layer with a thickness of 1-10 microns can be sprayed on the surface of the copper substrate to avoid reflection and heat dissipation caused by the high thermal conductivity of copper and thus prevent printing.

[0053] S2. According to the composition and specific gravity of the gradient composite material, the at least two printing powder feeding materials are respectively loaded into at least two powder feeding barrels and / or mixed and loaded into at least two powder feeding barrels.

[0054] Specifically, different printing powder materials are loaded into corresponding powder feeding buckets based on the composition and specific gravity of the gradient composite material. For example, when selecting Cu powder, Cr powder, and W powder for printing gradient composite contact materials, the Cu powder, Cr powder, and W powder are loaded into three separate powder feeding buckets. During printing, the powder flow rates of the three powder feeding buckets are simultaneously adjusted to achieve printing with different compositions.

[0055] Alternatively, the at least two printing powder feed materials are mixed at different mass ratios based on the composition and specific gravity of the gradient composite material to obtain mixed powders for different regions of the gradient composite material; and the mixed powders for different regions are placed into different powder feed buckets. For example, Cu powder and Cr powder are selected to print a CuCr material with a Gr content of 20% in the middle region and a CuCr material with a Gr content of 50% in the outer edge region. The Cu powder and Cr powder are then mixed at a mass ratio of 1:20% and 1:50, respectively, to obtain mixed powder materials for the two regions. The mixed powder materials for the two regions are then placed into two powder feed buckets. When printing the materials for the corresponding regions, the powder feed buckets corresponding to the mixed powder materials can be adjusted.

[0056] Furthermore, a combination of loading each printing powder material into a powder bucket separately and then mixing the powders into the bucket can be used. For example, to print a CuCr material with a Gr content of 30% using Cu powder and Cr powder, the Cu powder and Cr powder can be mixed in a 1:50 mass ratio and loaded into the powder bucket, while pure Cu powder can be loaded into the powder bucket separately. During printing, the powder feeding rates of the two powder buckets can be adjusted to achieve printing of the CuCr material with a Gr content of 30%. For another example, to print a composite contact material, bucket 1 can be filled with pure Cu powder, bucket 2 with CuCr powder or CuW powder, and bucket 3 with CuTe or CuBi powder.

[0057] Specifically, when the first element powder and the second element powder of the transverse gradient composite contact material are mixed, the content of the Cu powder is 40-100%; the mass ratio of the Cu powder to the Cr powder is 1:1-60%, the mass ratio of the Cu powder to the W powder is 1:1-60%, the mass ratio of the Cu powder to the Bi powder is 1:0.1-3%, and the mass ratio of the Cu powder to the Te powder is 1:0.1-3%.

[0058] Preferably, the at least two printing powder feeding materials are mixed and then loaded into a powder feeding barrel. After the mixing, the printing material has better uniformity, especially the addition of trace elements, and the distribution uniformity of the trace elements is better after the mixing.

[0059] It should be noted that at least two printing powder feeding materials can be loaded into the powder feeding bucket separately, or at least two printing powder feeding materials can be mixed in proportion and loaded into the powder feeding bucket, or several of the printing powder feeding materials can be mixed and loaded into the powder feeding bucket, and the remaining materials can be loaded into the powder feeding bucket separately, that is, the steps of loading the powder feeding bucket separately and mixing the powder can be used independently or simultaneously.

[0060] S3. The substrate is loaded into a laser printing device and fixed in a working area. The working box of the laser printing device is purged with an inert gas so that the oxygen content in the working box is less than 100 ppm. This prevents oxidation of the material during the laser printing process, which affects the performance of the printed material and also prevents cracking of the printed material.

[0061] S4. Use high-speed laser powder feeding technology to perform 3D printing based on a preset printing path. Different powder feeding barrels are linked or controlled separately according to the component proportion of the gradient composite material. The powder feeding speed of different powder feeding barrels is adjusted according to the component proportion of the gradient composite material and the powder feeding flow rate of the printing powder feeding material to achieve composition changes in different areas of the gradient composite material. The laser scanning power and laser movement speed are adjusted according to the proportion of different melting point components of the gradient composite material to obtain a printed sample.

[0062] Specifically, the preset printing path is input into the printing control system, and high-speed laser powder feeding technology is used for 3D printing production. During the printing process, by adjusting the different powder feeding flow rates of multiple powder feeding barrels, multiple powder feeding barrels can be linked or controlled separately to achieve the purpose of free control of the second element powder sent to the laser melting area, realize the adjustment and change of the composition of different areas, and thus achieve the effect of gradient compounding.

[0063] The powder feeding speed of the powder feeding bucket is negatively correlated with the specific gravity of the gradient composite material and the powder feeding flow rate of the printing powder feeding material. Specifically, the greater the specific gravity of a printing powder feeding material, the slower the powder feeding speed of the powder feeding bucket of that material, and the smaller the specific gravity, the faster the powder feeding speed of the powder feeding bucket of that material. The faster the powder feeding flow rate of a printing powder feeding material, the slower the powder feeding speed of the powder feeding bucket of that material, and the slower the powder feeding flow rate, the faster the powder feeding speed of the powder feeding bucket of that material.

[0064] It should be noted that the component density refers to the mass ratio of a specific component to all other components. The powder feeding speed refers to the movement speed of the powder feeding barrel. The powder feeding rate refers to the printing powder feeding material and is closely related to the fluidity of the printing powder feeding material itself.

[0065] Specifically, the powder feeding air flow rate of the printing powder feeding material is 5-15L / min, the powder feeding flow rate of all printing powder feeding materials is selected within 15s / 50g-23s / 50g, and the powder feeding speed of all powder feeding barrels is selected within 0.1-2rap / min.

[0066] Furthermore, during the printing process, due to changes in material composition, the printing process realizes the linked changes in laser scanning power and laser rate, effectively ensuring the quality of the printing process.

[0067] The laser scanning power is positively correlated with the proportion of the high-melting-point component, while the laser movement speed is negatively correlated with the laser scanning power. Specifically, the greater the content of the high-melting-point component, the greater the laser scanning power and the slower the laser movement speed; the smaller the content of the high-melting-point component, the lower the laser scanning power and the faster the laser movement speed. The high-melting-point component refers to the component with a relatively high melting point in the composite material. For example, Gr is a high-melting-point component in CuCr material.

[0068] Specifically, the laser scanning power is 3-10 kW, and the laser moving speed is 5-1000 cm / min.

[0069] S5. Performing heat treatment and surface treatment on the printed sample in sequence to obtain a gradient composite material.

[0070] First, the printed samples are heat treated. The heat treatment process is as follows: first, solution heat treatment is performed at a solution temperature of 800-1100°C and the temperature is kept at that temperature for 1-4 hours; then, aging heat treatment is performed at a temperature of 430-450°C and the temperature is kept at that temperature for 3-5 hours.

[0071] Then, the heat-treated sample is subjected to surface treatment. The surface treatment process is as follows: first, a shape correction treatment is performed, and then a surface processing treatment is performed according to the size of the finished part to obtain a gradient composite material.

[0072] The preparation method of this embodiment selects different printing powder materials according to the composition of the gradient composite material, and loads them into different powder feeding barrels for 3D printing. During the printing process, the different powder feeding barrels are linked or controlled separately, and the composition changes in different areas of the gradient composite material are achieved by adjusting the powder feeding speed of the powder feeding barrels. The quality of the printing process is guaranteed by controlling the laser scanning power and the laser movement speed, and the requirements of different compositions of the composite material during the printing process in different areas are realized.

[0073] The preparation method of this embodiment achieves gradient design and preparation of CuCr contact materials during the printing process by designing different powder compositions during the 3D printing process and optimizing the design of the 3D printing equipment structure and the printing process technology and parameters. This meets the requirements of different composition of the contact material during the printing process in different areas, and produces a high-performance gradient composite contact material. This meets the Cr content requirements of different parts of the vacuum switch contact, and further meets the requirements of medium and high voltage vacuum switches for different properties such as high electrical conductivity, thermal conductivity, compressive strength, and resistance to welding and ablation, thereby improving the performance of the vacuum switch.

[0074] Example 2

[0075] Based on the first embodiment, this embodiment provides a gradient composite material. The gradient composite material is prepared by the preparation method described in the first embodiment. The gradient composite material has several regions with different compositions.

[0076] Specifically, gradient composite materials include but are not limited to transverse gradient composite contact materials, gradient stainless steel materials, gradient high-temperature Ni alloy materials, and gradient high-temperature Ti alloy materials. The gradient composite of a gradient composite material means that the composite material has multiple regions with different compositions, and multiple regions can realize multi-dimensional gradient composites, which is not limited to multiple regions stacked up and down, nor is it limited to multiple regions being distributed laterally along the surface of the material; gradient composites can also be applied to any shape. For example, multiple regions with different compositions are stacked up and down to realize longitudinal gradient distribution; multiple regions with different compositions are distributed in sequence from one side to the other along the surface of the material to realize transverse gradient distribution; multiple regions with different compositions are divided and distributed from the center to the outside along the surface of the material to realize transverse gradient distribution, and so on.

[0077] Example 3

[0078] This embodiment further illustrates the preparation method of the gradient composite material through the following examples.

[0079] Example 1

[0080] Taking the CuCr30-CuCr50 / CrC gradient composite material as an example, the preparation method of the gradient composite material includes the following steps:

[0081] S1. Select copper substrate, pure copper powder, Cr powder, and ZrC powder;

[0082] S2. Mix 0.2% ZrC and pure copper powder evenly, put them into barrel No. 1, and put Cr powder into barrel No. 2.

[0083] S3. Place the copper substrate into the laser printing equipment and fix it in the working area. Purge the working box with inert gas to reduce the oxygen content to less than 100 ppm.

[0084] S4. Adjust the powder feeding speed of barrel 1 to 0.5rap / min, the powder feeding speed of barrel 2 to 0.6rap / min, the printing power to 4.4kW, and the laser moving speed to 600cm / min, so that CuCr30 containing 0.14% CrC can be printed; during the printing process, adjust the powder feeding speed of barrel 1 to 0.7rap / min, the powder feeding speed of barrel 2 to 0.33rap / min, the printing power to 4.8kW, and the laser moving speed to 570cm / min, so that CuCr50 containing 0.14% CrC can be printed in a gradient manner.

[0085] S5. The printed samples are subjected to solution heat treatment and aging temperature; then, the heat-treated samples are first subjected to shape correction treatment and surface processing according to the size of the finished parts to obtain a gradient composite material.

[0086] Example 2

[0087] Taking the TC4-TC6 gradient composite material as an example, the preparation method of the gradient composite material includes the following steps:

[0088] S1. Select copper substrate, TC4 titanium alloy powder, and TC46 titanium alloy powder;

[0089] S2. Put TC4 titanium alloy powder into barrel No. 1 and put TC46 titanium alloy powder into barrel No. 2;

[0090] S3. Place the copper substrate into the laser printing equipment and fix it in the working area. Purge the working box with inert gas to reduce the oxygen content to less than 100 ppm.

[0091] S4: Adjust the powder feeding speed of barrel 1 to 0.4 rap / min, the powder feeding speed of barrel 2 to 0 rap / min, the printing power to 2.8 kW, the laser moving speed to 430 cm / min, and work in the area where TC4 printing is required; if it is necessary to transition to TC6, gradually adjust the powder feeding speed of barrel 1 to 0, and the powder feeding speed of powder feeding barrel 2 to 0.4 rap / min, ensuring that the total powder feeding rate of the two barrels is maintained at 0.4 rap / min, and a gradient composite material with a steady transition can be obtained; and this step can be used alternately during the printing process;

[0092] S5. The printed samples are subjected to solution heat treatment and aging temperature; then, the heat-treated samples are first subjected to shape correction treatment and surface processing according to the size of the finished parts to obtain a gradient composite material.

[0093] Example 3

[0094] Taking the CuCrNb-316 stainless steel gradient composite material as an example, the preparation method of the gradient composite material includes the following steps:

[0095] S1. Select copper substrate, CuCrNb powder, and 316 stainless steel powder;

[0096] S2. Put CuCrNb powder into barrel No. 1 and put 316 stainless steel powder into barrel No. 2;

[0097] S3. Place the copper substrate into the laser printing equipment and fix it in the working area. Purge the working box with inert gas to reduce the oxygen content to less than 100 ppm.

[0098] S4. Adjust the powder feeding speed of barrel No. 1 to 0.65rap / min, the powder feeding speed of barrel No. 2 to 0rap / min, the printing power to 6.5kW, the laser moving speed to 320cm / min, and print CuCrNb high-temperature resistant alloy on the inner circle; when it is necessary to print the outer circle 316 stainless steel, adjust the powder feeding speed of barrel No. 1 step by step to 0.65rap / min, 0.4rap / min, 0.2rap / min, and 0rap / min, and adjust the powder feeding speed of barrel No. 2 step by step to 0.2rap / min, 0.4rap / min, 0.6rap / min, and 0.8rap / min to the maximum, and gradually reduce the printing power from 6.5kW to 5.5kW. The laser moving speed is gradually increased to 710cm / min, and a gradient composite structure material with CuCrNb inside and 316 stainless steel outside can be obtained.

[0099] The above is a further detailed description of the present invention in conjunction with specific preferred embodiments, and the specific implementation of the present invention should not be considered to be limited to these descriptions. For those skilled in the art of the present invention, without departing from the concept of the present invention, several simple deductions or substitutions can be made, which should be considered to fall within the scope of protection of the present invention.

Claims

1. A method for preparing a gradient composite material, characterized in that: The gradient composite material is a gradient composite contact material for a vacuum switch, and the preparation method comprises the steps of: S1. Select a substrate and select at least two printing powder feed materials based on the composition of the gradient composite contact material; the at least two printing powder feed materials include a first element powder, a second element powder, and a trace element powder, the first element powder includes Cu powder, and the Cu powder is added with an endothermic material powder, the second element powder includes Cr powder, and the trace element powder includes one or more of Bi powder and Te powder; the endothermic material powder includes one or more of ZrC, LaB6, and CrC; the mass of the endothermic material powder is less than or equal to 0.3% of the mass of the Cu powder; S2. According to the composition and specific gravity of the gradient composite material, the at least two printing powder feeding materials are respectively loaded into at least two powder feeding buckets and / or mixed and loaded into at least two powder feeding buckets; S3, loading the substrate into a laser printing device and fixing it in a working area, and performing inert gas purge on a working box of the laser printing device; S4. Using high-speed laser powder feeding technology, 3D printing is performed based on a preset printing path. Different powder feeding barrels are linked or separately controlled according to the component specific gravity of the gradient composite material. The powder feeding speeds of different powder feeding barrels are adjusted according to the component specific gravity of the gradient composite material and the powder feeding flow rate of the printing powder feeding material to achieve composition changes in different regions of the gradient composite material. In addition, as the material composition changes during the printing process, the laser scanning power and laser movement speed are adjusted according to the specific gravity of different melting point components of the gradient composite material to obtain a printed sample; wherein, the powder feeding air flow rate of the printing powder feeding material is 5-15L / min, the powder feeding flow rate of the printing powder feeding material is 15s / 50g-23s / 50g, and the powder feeding speed of the powder feeding barrel is 0.1-2rap / min; the laser scanning power is 3-10kW, and the laser movement speed is 5-1000cm / min; S5. Performing heat treatment and surface treatment on the printed sample in sequence to obtain a gradient composite contact material, wherein the gradient composite contact material has multiple regions distributed laterally along the surface of the material, and the material in each region has different contents of Cu and Cr.

2. The method for preparing a gradient composite material according to claim 1, wherein: When the first element powder, the second element powder and the trace element powder are mixed, The content of the Cu powder is 40-100%; The mass ratio of the Cu powder to the Cr powder is 1:1-60%; The mass ratio of the Cu powder to the Bi powder is 1:0.1-3%, and the mass ratio of the Cu powder to the Te powder is 1:0.1-3%.

3. The method for preparing a gradient composite material according to claim 1, wherein: Step S2 includes: According to the composition and proportion of the gradient composite material, different printing powder feeding materials are respectively loaded into the corresponding powder feeding barrels; or, According to the composition and proportion of the gradient composite material, the at least two printing powder feeding materials are mixed in different mass proportions to obtain mixed powders in different regions of the gradient composite material; and the mixed powders in different regions are loaded into different powder feeding barrels.

4. The method for preparing a gradient composite material according to claim 1, wherein: The powder feeding speed of the powder feeding barrel is negatively correlated with the component specific gravity of the gradient composite material and negatively correlated with the powder feeding flow rate of the printing powder feeding material; The laser scanning power is positively correlated with the proportion of the high melting point component, and the laser moving speed is negatively correlated with the laser scanning power.

5. The method for preparing a gradient composite material according to claim 1, wherein: The heat treatment includes solution heat treatment and aging heat treatment; The solution heat treatment temperature is 800-1100°C and the temperature is kept for 1-4 hours; The aging temperature of the aging heat treatment is 430-450° C., and the holding time is 3-5 hours.

6. A gradient composite material, characterized in that The gradient composite material is prepared by the preparation method according to any one of claims 1 to 5, and is a gradient composite contact material for a vacuum switch, having multiple regions distributed laterally along the surface of the material, and the material in each region has different contents of Cu and Cr.

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