Densely-arranged ceramic ball reinforced metal-based composite board and preparation method thereof

Abstract

The invention discloses a densely-arranged ceramic ball reinforced metal-based composite board which comprises an upper metal backboard, a lower metal backboard and ceramic balls and further comprises a honeycomb limiting frame arranged between the upper metal backboard and the lower metal backboard, the honeycomb limiting frame comprises a plurality of densely-arranged honeycomb structure units, and the honeycomb structure units are provided with hexagonal through holes extending vertically. The ceramic balls are arranged in the hexagonal through holes so that the ceramic balls can be restrained and limited by the hexagonal through holes in the direction parallel to the metal back plate, gaps between the ceramic balls and the hexagonal through holes are filled with hot-pressed and sintered metal powder, and the ceramic balls can be restrained and limited by the vertically-filled metal powder in the direction perpendicular to the metal back plate. The ceramic balls are restrained and limited by the hole walls of the hexagonal through holes in the direction parallel to the metal back plate; and in the direction perpendicular to the metal back plate, the upper parts of the ceramic balls are covered by the metal powder, the lower parts of the ceramic balls are supported by the metal powder, and the upper and lower filling metal powder can restrain and limit the ceramic balls, so that the positions of the ceramic balls can be effectively restrained, and the protection efficiency of the composite plate is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of the preparation of ceramic ball reinforced metal matrix composites, and particularly relates to a closely arranged ceramic ball reinforced metal matrix composite plate and a preparation method thereof. Background Art

[0002] With the continuous development of armor piercing and armor penetration technologies, the threats to armored vehicles are increasing continuously. Traditional homogeneous steel armor, homogeneous aluminum alloy armor, and homogeneous titanium alloy armor cannot meet the protection requirements, and metal-ceramic composite armor has emerged as the times require. In 1976, the British successfully developed the "Chobham armor". The "Chobham armor" is a layered metal-ceramic composite armor. It is reported that the "Chobham armor" is 3 times more effective against armor-piercing projectiles than rolled homogeneous steel armor and can resist the attack of 105mm armor-piercing fin-stabilized discarding sabot rounds. However, the "Chobham armor" has the following disadvantages: the ceramic plate is prone to overall fragmentation under the action of metal jets and high-speed stress waves of projectiles; it is easy to separate between layers under the action of transmitted stress waves and transverse stress waves, and the structural integrity is poor; the ceramic layer is mostly composed of rectangular and hexagonal ceramic plates spliced together, and there are protection blind spots at the joints.

[0003] Ceramic ball reinforced metal matrix composites are a kind of protective materials with excellent performance. Compared with the "Chobham armor", using ceramic balls as the reinforcement can avoid the overall fragmentation of the ceramic layer and improve the ability to resist multiple projectile strikes. Compared with the metal matrix, the ceramic balls have the characteristics of high hardness and high melting point, can grind projectiles or fragments, effectively reduce the kinetic energy, and thus protect the safety of personnel and equipment. In the composite material, the metal matrix restricts the ceramic balls, effectively preventing the composite material from fragmenting; the contact area between the ceramic and the metal is large, and the ceramic balls are embedded in the metal, and the structural integrity is relatively good. Therefore, using ceramic balls as ceramic reinforcements to prepare ceramic ball reinforced aluminum matrix composite plates is a potential protective material.

[0004] In ceramic sphere-reinforced aluminum matrix composites, the arrangement of ceramic spheres has an important influence on their protective performance. To make the arrangement of ceramic spheres controllable, researchers have invented various methods. Patent CN 113959264 A discloses a non-close-packed ceramic sphere-reinforced aluminum matrix composite armor and its preparation method. In this method, perforated metal plates are first used to fix ceramic spheres on the back plate, and then the aluminum matrix is poured in by high-pressure infiltration, finally forming a ceramic sphere-reinforced aluminum matrix composite armor. Although the composite material prepared by this method provides effective constraints on ceramic spheres and has good performance against multiple impacts, it has many holes in the metal plate, low efficiency, high cost, and a relatively low volume fraction of ceramics to ensure the fluidity of the metal. Patent CN113899249A discloses a metal-encapsulated ceramic sphere composite armor, preparation method, and lightweight target plate against multiple projectiles. This method first processes round holes and through holes on both sides of the titanium alloy plate material, then assembles and fixes the ceramic spheres and the titanium alloy plate in a steel shell to form an infiltration assembly, and finally pours 6061 aluminum liquid into the gaps of the infiltration assembly by reverse infiltration. However, this method requires processing round holes and through holes on the metal plate and has high requirements for processing accuracy.

[0005] In summary, in the preparation of ceramic sphere-reinforced metal matrix composite plates, the method of using perforated metal plates to fix ceramic spheres + casting is mostly adopted. In this method, corresponding hole positions need to be processed for each ceramic sphere, and the assembly workload of ceramic spheres is large, making it difficult for large-scale production. Therefore, it is necessary to optimize the design of the preparation process of ceramic sphere-reinforced metal matrix composite plates. Summary of the Invention

[0006] The first technical problem to be solved by the present invention is to propose a close-packed ceramic sphere-reinforced metal matrix composite plate with simpler fixation of ceramic spheres in view of the above technical status.

[0007] The second technical problem to be solved by the present invention is to propose a preparation method of a close-packed ceramic sphere-reinforced metal matrix composite plate that is conducive to mass production in view of the above technical status.

[0008] The technical solution adopted by the present invention to solve the first technical problem is as follows: A close-packed ceramic sphere-reinforced metal matrix composite plate includes upper and lower metal back plates and ceramic spheres. It is characterized in that it further includes a honeycomb limiting frame arranged between the upper and lower metal back plates. The honeycomb limiting frame includes a plurality of close-packed honeycomb structure units. The honeycomb structure units are provided with vertically extending hexagonal through holes. The ceramic spheres are arranged in the hexagonal through holes, so that the ceramic spheres are constrained and limited in the direction parallel to the metal back plate by the hexagonal through holes. The gaps between the ceramic spheres and the hexagonal through holes are filled with hot-pressed sintered metal powder, so that the ceramic spheres are constrained and limited in the direction perpendicular to the metal back plate by the metal powder filled above and below.

[0009] Preferably, 1 to 8 honeycomb limit frames are stacked, and one layer of the ceramic balls is closely arranged in each honeycomb limit frame. The ceramic ball layers are distributed with dislocation, and the ceramic balls in the upper layer are directly above the gaps between the ceramic balls in the lower layer, thereby filling the weak protection areas of the single-layer ceramic balls.

[0010] Specifically, the side length of the hexagonal through holes of the honeycomb limit frame is 0.58 to 0.75 times the radius of the ceramic balls, and the hole depth of the hexagonal through holes is 1.2 to 2 times the diameter of the ceramic balls.

[0011] Specifically, the metal powder has the same material as the honeycomb limit frame.

[0012] Preferably, the sintering temperature of the metal powder is 100 to 500 °C lower than the melting point of the metal powder, the sintering vacuum degree is 0.001 to 1 Pa, and the sintering pressure is 5 to 50 MPa.

[0013] Preferably, the thickness of the metal backboard is 1 to 8 mm, the thickness of the honeycomb limit frame is 4 to 12 mm, and the diameter of the ceramic balls is 2 to 20 mm.

[0014] Preferably, the gap between adjacent ceramic balls in each layer is the sum of the wall thickness of the honeycomb limit frame and the assembly gap, which is 0.1 to 2 mm, and the vertical interval between adjacent ceramic balls is 2 to 8 mm.

[0015] The technical solution adopted by the present invention to solve the second technical problem is: a preparation method of a closely arranged ceramic ball reinforced metal matrix composite plate, which is characterized in that it is used to prepare the closely arranged ceramic ball reinforced metal matrix composite plate according to any one of the above, including the steps:

[0016] Step 1, dimension design: According to the selected diameter of the ceramic balls, determine the side length and hole depth of the hexagonal through holes of the honeycomb limit frame in proportion, and determine the length and width of the honeycomb limit frame according to the size of the sample;

[0017] Step 2, surface pretreatment of ceramic balls: Remove impurities on the surface of the ceramic balls, coat a layer of copper, nickel or silver on the surface of the ceramic balls, and wash and dry the ceramic balls coated with metal;

[0018] Step 3, powder laying and ceramic ball assembly: Place a honeycomb limit frame on the metal backboard, lay a layer of metal powder in each hexagonal through hole, then fill the matching layer of ceramic balls into the hexagonal through holes, and then fill the metal powder to complete the construction of the first layer; If the number of layers of ceramic balls to be filled exceeds 1 layer, place another honeycomb limit frame on the first layer and repeat the steps of laying metal powder and filling ceramic balls similar to the first layer; After all the layers are constructed, cover the metal backboard above the last layer, restrain the four sides of the whole structure with steel plates, and fill the gap between the honeycomb limit frame and the restraining steel plates with metal powder;

[0019] Step 4. Hot pressing and sintering: The hot pressing and sintering method bonds the above structures together to form a ceramic ball reinforced metal matrix composite plate.

[0020] Preferably, when performing Step 2, the ceramic balls are placed in a solution containing 50 - 75% by volume of ethanol and ultrasonically treated for 15 - 40 min to remove surface impurities. By means of electroless plating, a layer of copper, nickel or silver is plated on the surface of the ceramic balls. The ceramic balls plated with metal are washed 2 - 4 times with deionized water or absolute ethanol, and then placed in an oven and dried at 105 - 120 °C for 30 - 120 min.

[0021] Preferably, when performing Step 4, a layer of graphite paper is padded on the upper, lower, left and right sides of the mold and the plate to be sintered. The assembled plate to be sintered is placed in the corresponding mold. When the vacuum degree reaches 0.001 - 1 Pa, heating and pressure sintering are started. The heating rate is 2 - 15 °C / min, and the sintering temperature is 100 - 500 °C below the melting point of the metal powder. When the sample temperature drops below 60 °C, the vacuum is broken, the furnace door is opened, and the sample is taken out of the mold, and the graphite paper on the surface of the sample is removed.

[0022] Compared with the prior art, the advantages of the present invention are as follows: The present invention adopts a honeycomb limiting frame, so there is no need to process corresponding hole positions for each ceramic ball, thus reducing the assembly workload. The ceramic balls are located inside the hexagonal through holes opened in the honeycomb limiting frame. In the direction parallel to the metal backplane, they will be restricted and positioned by the hole walls of the hexagonal through holes; while in the direction perpendicular to the metal backplane, the upper parts of the ceramic balls are covered by the metal powder, and the lower parts are supported by the metal powder. The metal powder filled in the upper and lower parts will restrict and position them, so that the position of the ceramic balls can be effectively restricted, and the protection efficiency of the composite plate can be improved. Description of the Drawings

[0023] Figure 1 is a schematic structural diagram of Embodiment 1 of the present invention (the metal powder is hidden);

[0024] Figure 2 is a schematic structural diagram of the honeycomb limiting frame and the ceramic balls of Embodiment 1 of the present invention;

[0025] Figure 3 is a schematic structural diagram of the honeycomb limiting frame of Embodiment 1 of the present invention;

[0026] Figure 4 is a cross-sectional view of the first layer of Embodiment 1 of the present invention;

[0027] Figure 5 is the sintering temperature curve of Embodiment 1 of the present invention;

[0028] Figure 6 is the pressure control curve of Embodiment 1 of the present invention;

[0029] Figure 7 Schematic diagram of Embodiment 3 of the present invention (the metal powder is hidden). Detailed implementation manners

[0030] The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments.

[0031] Embodiment 1

[0032] As Figures 1 to 3 shown, it is a preferred embodiment of a closely-packed ceramic ball-reinforced metal matrix composite plate and its preparation method according to the present invention. The closely-packed ceramic ball-reinforced metal matrix composite plate of this embodiment includes upper and lower metal backplates 1, a honeycomb limiting frame 2, and ceramic balls 3. The honeycomb limiting frame 2 is arranged between the upper and lower metal backplates 1 and includes a plurality of closely-packed honeycomb structure units. The honeycomb structure units are provided with vertically extending hexagonal through-holes 21. The ceramic balls 3 are arranged in each hexagonal through-hole 21, so that the ceramic balls 3 are constrained and limited in the direction parallel to the metal backplate 1 by the hexagonal through-holes 21. Metal powder 4 sintered by hot pressing is filled in the gap between the ceramic balls 3 and the hexagonal through-holes 21, so that the ceramic balls 3 are constrained and limited in the direction perpendicular to the metal backplate 1 by the metal powder 4 filled above and below. The metal powder 4 has the same material as the honeycomb limiting frame 2.

[0033] One to eight honeycomb limiting frames 2 can be stacked. In this embodiment, 5 honeycomb limiting frames 2 are stacked. Each honeycomb limiting frame 2 is closely packed with one layer of the ceramic balls 3. The ceramic balls 3 are distributed with a stagger between layers. The ceramic balls 3 in the upper layer are directly above the gaps between the ceramic balls 3 in the lower layer.

[0034] The preparation method includes the following steps:

[0035] Step 1. Dimension design:

[0036] According to the diameter of the selected ceramic balls 3, the side length and hole depth of the hexagonal through-holes 21 of the honeycomb limiting frame 2 are determined proportionally, and the length and width of the honeycomb limiting frame 2 are determined according to the size of the sample. In this embodiment, the metal backplate 1 is a 6061 aluminum alloy plate with a side length of 200 mm and a thickness of 2 mm. The ceramic balls 3 are Al 2 O 3 ceramic balls 3 with a diameter of 8 mm. The honeycomb limiting frame 2 is a honeycomb aluminum plate with a side length of 5 mm, a height of 12 mm, and a wall thickness of 1 mm for the hexagonal through-holes 21. The number of layers of the ceramic balls 3 is 5 layers, and the sizes of each layer of ceramic balls 3 and the honeycomb limiting frame 2 are the same. The metal powder 4 filled in the honeycomb structure is 6061 aluminum alloy powder.

[0037] Step 2. Surface pretreatment of the ceramic balls:

[0038] Remove the impurities on the surface of the ceramic balls 3, coat a layer of copper, nickel or silver on the surface of the ceramic balls 3, and wash and dry the ceramic balls 3 coated with metal. In this embodiment, 2600 g of 8-mm ceramic balls 3 are put into a 50% ethanol solution and ultrasonically treated for 30 min, and then put into an oven and dried at 65 °C for 60 min. After the ceramic balls 3 return to room temperature, they are put into a solution containing copper sulfate (CuSO 4 ·5H 2 O) and sodium citrate (C 6 H 5 Na 3 O 7 ·2H 2 O). Sodium hydroxide is added to adjust the pH value of the solution to 9-11, and nickel sulfate (NiSO 4 ·6H 2 O), boric acid (H 3 BO 3 ) as a stabilizer and sodium hypophosphite (NaH 2 PO 2 ·H 2 O) as a reducing agent are added. After reacting for 30 min, take it out, wash it 3 times with deionized water and then put it into a 50% ethanol solution and ultrasonically treat it for 30 min, and then put it into an oven and dry it at 120 °C for 60 min.

[0039] Step 3: Powder spreading and ceramic ball assembly:

[0040] Place a honeycomb limiting frame 2 on the metal backplane 1, spread a layer of metal powder 4 in each hexagonal through hole 21, then fill a layer of matching ceramic balls 3 into the hexagonal through holes 21, and then fill the metal powder 4 to complete the construction of the first layer, as Figure 4 shown; if the number of layers of ceramic balls 3 to be filled exceeds 1 layer, then place another honeycomb limiting frame 2 on the first layer and repeat the steps of spreading the metal powder 4 and filling the ceramic balls 3 similar to the first layer; until after all the layers are constructed, cover the metal backplane 1 above the last layer, restrain the four sides of the whole structure with a steel plate, and fill the gap between the honeycomb limiting frame 2 and the restraining steel plate with the metal powder 4. If the number of layers of ceramic balls 3 to be filled exceeds 1 layer, when constructing the upper layer, after the ceramic balls 3 are filled into the hexagonal through holes 21, do not fill the metal powder 4 completely, and wait until after placing a new honeycomb limiting frame 2, synchronize with the spreading of the metal powder 4 of the new layer. Therefore, this step can be specifically divided into the following steps according to the number of layers to be constructed:

[0041] The first layer: First, place the designed honeycomb limiting frame 2 on a 6061 aluminum alloy plate, and evenly spread a layer of 6061 aluminum alloy powder with a thickness of about 8 mm in the cavity of each honeycomb structure. Then, fill the ceramic balls 3 matching the honeycomb structure into the honeycomb structure cavity.

[0042] Second layer: Place the honeycomb spacer 2 on the first layer. Uniformly spread a layer of metal powder 4 in the chambers of each honeycomb structure, with a thickness of approximately 12 mm. Fill the cavities of the honeycomb structure with ceramic balls 3.

[0043] According to the structural design of Embodiment 1, repeat the operation steps of the second layer three times. Fill the chambers of the honeycomb structure above the last layer with metal powder 4, cover it with a 6061 aluminum alloy backplate, as Figures 1 to 4 shown, and then fix it.

[0044] Step 4: Vacuum hot pressing and sintering:

[0045] Bond the above structure together by hot pressing and sintering to form a ceramic ball 3 reinforced metal matrix composite plate. Specifically, place a layer of graphite paper on the top, bottom, left, and right of the mold and the plate to be sintered. Put the assembled plate to be sintered into the corresponding mold. When the vacuum degree reaches below 0.05 Pa, start heating and pressurizing for sintering. The sintering temperature curve is as Figure 5 shown. The sintering temperature is 500 °C, and the heating regime is: room temperature to 400 °C, heating rate is 10 °C / min; keep the temperature at 400 °C for 30 min; 400 to 500 °C, heating rate is 5 °C / min, and the holding time is 30 min; then stop holding, and cool with the furnace. The pressure control curve is as Figure 6 shown. After the sample is placed in the mold, apply a pre-tightening force of 400 kN (i.e., a pressure of 10 MPa). When the temperature rises to 400 °C, the pressure gradually rises to 600 kN (i.e., a pressure of 15 MPa), hold the pressure for 30 min. When the temperature rises to 500 °C, the pressure gradually decreases to 400 kN (i.e., a pressure of 10 MPa), and hold the pressure for 30 min.

[0046] When the sample temperature drops below 60 °C, break the vacuum, open the furnace door, take out the sample from the mold, and remove the graphite paper on the surface of the sample to obtain the ceramic ball 3 reinforced aluminum matrix composite plate.

[0047] Embodiment 2

[0048] This embodiment includes the following steps:

[0049] Step 1: Dimension design:

[0050] Select a 2205 stainless steel plate with a side length of 200 mm and a thickness of 1 mm as the metal backplate 1. Select Si 3 N 4 ceramic balls with a diameter of 8 mm as the ceramic balls 3. Select a honeycomb stainless steel plate with a side length of 5 mm, a height of 12 mm, and a wall thickness of 1 mm for the hexagonal through-holes 21 of the honeycomb spacer 2. The number of layers of the ceramic balls 3 is 3 layers, and the sizes of each layer of the ceramic balls 3 and the honeycomb stainless steel plate are the same. Fill the honeycomb structure with 2205 stainless steel powder.

[0051] Step 2. Surface pretreatment of ceramic balls:

[0052] Put 1300 g of 8-mm ceramic balls 3 into a 50% ethanol solution and ultrasonically treat for 30 min, then put them into an oven and dry at 65 °C for 60 min. After the ceramic balls 3 return to room temperature, first put them into the sensitizing solution, and after sensitization for 30 min, wash them 3 times with deionized water. Next, put them into the activation solution and take them out after 30 min. Finally, put them into the nickel plating solution, take them out after 40 min, wash them 3 times with deionized water, ultrasonically treat them in a 50% ethanol solution for 30 min, and put them into an oven and dry at 120 °C for 60 min.

[0053] The sensitizing solution consists of SnCl 2 ·2H 2 O and concentrated hydrochloric acid, with concentrations of 15 g / L and 50 mL / L respectively. The activator consists of PdCl 2 , H 3 BO 3 and concentrated hydrochloric acid, with concentrations of 0.25 g / L, 20 g / L, and 0.5 g / L respectively. The nickel plating solution consists of NiSO 4 ·7H 2 O, NaH 2 PO 2 ·H 2 O, C 3 H 6 O 3 (lactic acid), H 3 BO 3 , (NH 4 ) 2 MoO 4 , CH 3 COONa, NaF, with concentrations of 25 g / L, 30 g / L, 10 mL / L, 15 g / L, 10 mg / L, 25 g / L, and 1 g / L respectively.

[0054] Step 3. Powder spreading and ceramic ball assembly:

[0055] First layer: First, place the designed honeycomb limit frame 2 on the 2205 stainless steel plate, and evenly spread a layer of 2205 stainless steel powder with a thickness of about 8 mm in each chamber of the honeycomb structure. Then, fill the ceramic balls 3 matching the honeycomb structure into the cavities of the honeycomb structure.

[0056] Second layer: Place the honeycomb limit frame 2 on the first layer, evenly spread a layer of metal powder 4 with a thickness of about 12 mm in each chamber of the honeycomb structure, and fill the ceramic balls 3 into the cavities of the honeycomb structure.

[0057] According to the structural design of Embodiment 2, repeat the operation steps of the second layer three times. Spread the metal powder 4 in the chamber of the honeycomb structure above the last layer, cover it with a 2205 stainless steel back plate, and fix it.

[0058] Step 4: Vacuum hot pressing and sintering:

[0059] Lay a layer of graphite paper on the upper, lower, left, and right of the mold and the plate to be sintered. Place the assembled plate to be sintered into the corresponding mold. When the vacuum degree reaches below 0.05 Pa, start heating and pressure sintering. The sintering temperature is 1100 °C, and the heating system is as follows: room temperature to 900 °C, the heating rate is about 10 °C / min; keep warm at 900 °C for 30 min; 900 - 1100 °C, the heating rate is 5 °C / min, and the holding time is 30 min; then stop holding, and cool with the furnace. After the sample is placed in the mold, apply a pre-tightening force of 400 kN (i.e., the pressure is 10 MPa). When the temperature rises to 900 °C, the pressure gradually rises to 600 kN (i.e., the pressure is 15 MPa), and keep the pressure for 30 min. When the temperature rises to 1100 °C, the pressure gradually decreases to 400 kN (i.e., the pressure is 10 MPa), and keep the pressure for 30 min.

[0060] When the temperature of the sample drops below 60 °C, break the vacuum, open the furnace door, take out the sample from the mold, and remove the graphite paper on the surface of the sample to obtain the Si 3 N 4 ceramic ball reinforced 2205 stainless steel matrix composite plate.

[0061] Embodiment 3

[0062] This embodiment, as Figure 7 shown, has two different sizes of multi-layer honeycomb limit frames 2 and two different sizes of ceramic balls 3. The difference between these two honeycomb limit frames 2 lies in their different side lengths, and the sizes of the ceramic balls 3 placed in the hexagonal holes are also different. The side length of the hexagonal through hole 21 of the larger honeycomb limit frame 2 is 5 mm, the height is 12 mm, and the diameter of the filled ceramic ball 3 is 8 mm; the side length of the hexagonal through hole 21 of the smaller honeycomb limit frame 2 is 2.5 mm, the height is 6 mm, and the diameter of the filled ceramic ball 3 is 4 mm.

[0063] The preparation method includes the following steps:

[0064] Step 1: Size design:

[0065] Select a 6061 aluminum alloy plate with a side length of 200 mm and a thickness of 1 mm for the metal back plate 1, and select Si 3 N 4Ceramic balls, honeycomb aluminum plates with honeycomb structure unit side lengths of 5 mm and 2.5 mm, heights of 12 mm and 6 mm, and wall thicknesses of 1 mm are selected corresponding to the honeycomb limit frame 2. The number of layers of 8 mm ceramic balls 3 is 3 layers, and the number of layers of 4 mm ceramic balls 3 is 2 layers. 6061 aluminum alloy powder is filled in the honeycomb structure. Different diameters of Si 3 N 4 The structure of the ceramic ball reinforced aluminum matrix composite plate is as Figure 6 shown.

[0066] Step 2: Surface pretreatment of ceramic balls:

[0067] Put 1300 g of 8 mm Si 3 N 4 ceramic balls 3 and 360 g of 4 mm Si 3 N 4 ceramic balls 3 into 50% ethanol solution respectively and ultrasonically treat for 30 min, then put them into an oven and dry at 65 °C for 60 min. After the ceramic balls 3 return to room temperature, first put them into the sensitizing solution, after sensitizing for 30 min, wash them 3 times with deionized water. Next, put them into the activating solution and take them out after 30 min. Finally, put them into the nickel plating solution, take them out after 40 min, wash them 3 times with deionized water, ultrasonically treat them in 50% ethanol solution for 30 min, and put them into an oven and dry at 120 °C for 60 min.

[0068] The sensitizing solution consists of SnCl 2 ·2H 2 O and concentrated hydrochloric acid, and their concentrations are 15 g / L and 50 mL / L respectively. The activator consists of PdCl 2 , H 3 BO 3 and concentrated hydrochloric acid, and their concentrations are 0.25 g / L, 20 g / L, and 0.5 g / L respectively. The nickel plating solution consists of NiSO4·7H 2 O, NaH 2 PO 2 ·H 2 O, C 3 H 6 O 3 (lactic acid), H 3 BO 3 , (NH 4 ) 2 MoO 4 , CH 3 COONa, NaF, and their concentrations are 25 g / L, 30 g / L, 10 mL / L, 15 g / L, 10 mg / L, 25 g / L, and 1 g / L respectively.

[0069] Step 3: Powder spreading and ceramic ball assembly:

[0070] First layer: First, place the honeycomb limiting frame 2 with a side length of 5 mm of the hexagonal through-hole 21 on the 6061 aluminum alloy plate, and evenly lay a layer of 6061 aluminum alloy powder in each chamber of the honeycomb structure, with a thickness of about 8 mm. Then, fill the cavities of the honeycomb structure with 8 mm Si 3 N 4 ceramic balls 3.

[0071] Second layer: Place the honeycomb limiting frame 2 on the first layer, evenly lay a layer of metal powder 4 in each chamber of the honeycomb structure, with a thickness of about 12 mm, and fill the cavities of the honeycomb structure with ceramic balls 3.

[0072] Third layer: Repeat the operation steps of the second layer once to complete the assembly of the ceramic balls 3 in the third layer, and fill the chambers of the honeycomb structure in the third layer with metal powder 4.

[0073] Fourth layer: Next, place the honeycomb limiting frame 2 with a side length of 2.5 mm of the hexagon on the third layer, and evenly lay a layer of 6061 aluminum alloy powder in each chamber of the honeycomb structure, with a thickness of about 4 mm. Then, fill the cavities of the honeycomb structure with 4 mm Si 3 N 4 ceramic balls 3.

[0074] Fifth layer: Repeat the operation steps of the fourth layer once to complete the assembly of the ceramic balls 3 in the fifth layer.

[0075] Fill the chambers of the honeycomb structure above the last layer with metal powder 4, cover the 6061 aluminum alloy backboard, and fix it.

[0076] Step 4. Vacuum hot pressing and sintering:

[0077] Lay a layer of graphite paper on the top, bottom, left, and right of the mold and the plate to be sintered. Place the assembled plate to be sintered into the corresponding mold. When the vacuum degree reaches below 0.05 Pa, start heating and pressurizing for sintering. The sintering temperature is 520 °C, and the heating system is as follows: room temperature to 400 °C, with a heating rate of about 10 °C / min; keep the temperature at 400 °C for 30 min; 400 - 520 °C, with a heating rate of 5 °C / min and a holding time of 30 min; then stop holding and cool with the furnace. After the sample is placed in the mold, apply a pre-tightening force of 400 kN (i.e., a pressure of 10 MPa). When the temperature rises to 400 °C, the pressure gradually rises to 600 kN (i.e., a pressure of 15 MPa), and keep the pressure for 30 min. When the temperature rises to 520 °C, the pressure gradually decreases to 400 kN (i.e., a pressure of 10 MPa), and keep the pressure for 30 min.

[0078] When the temperature of the sample drops below 60 °C, break the vacuum, open the furnace door, take out the sample from the mold, and remove the graphite paper on the surface of the sample to obtain Si 3 N 4 ceramic ball reinforced aluminum matrix composite plates.

Claims

1. A densely packed ceramic ball reinforced metal matrix composite plate, comprising an upper and a lower metal back plate and ceramic balls, characterized in that: It also includes a honeycomb limiting frame arranged between the upper and lower metal back plates, the honeycomb limiting frame includes a plurality of closely packed honeycomb structural units, the honeycomb structural units are provided with vertically extending hexagonal through holes, ceramic balls are arranged in each hexagonal through hole, so that the ceramic balls are constrained and limited by the hexagonal through holes in a direction parallel to the metal back plate, and the gap between the ceramic balls and the hexagonal through holes is filled with hot-pressed sintered metal powder, so that the ceramic balls are constrained and limited by the metal powder filled up and down in a direction perpendicular to the metal back plate.

2. The densely packed ceramic ball reinforced metal matrix composite plate according to claim 1, characterized in that: The honeycomb limiting frames are stacked in 1 to 8 pieces, each of which has a layer of ceramic balls densely arranged in it. The ceramic balls are staggered between the layers, and the ceramic balls in the upper layer are located directly above the gaps between the ceramic balls in the lower layer.

3. The densely packed ceramic ball reinforced metal matrix composite plate according to claim 1, characterized in that: The side length of the hexagonal through hole of the honeycomb limiting frame is 0.58 to 0.75 times the radius of the ceramic ball, and the hole depth of the hexagonal through hole is 1.2 to 2 times the diameter of the ceramic ball.

4. The densely packed ceramic ball reinforced metal matrix composite plate according to claim 1, characterized in that: The metal powder is made of the same material as the honeycomb limiting frame.

5. The densely packed ceramic ball reinforced metal matrix composite plate according to claim 1, characterized in that: The sintering temperature of the metal powder is 100-500° C. lower than the melting point of the metal powder, the sintering vacuum degree is 0.001-1 Pa, and the sintering pressure is 5-50 MPa.

6. The densely packed ceramic ball reinforced metal matrix composite plate according to claim 1, characterized in that: The thickness of the metal back plate is 1-8 mm, the thickness of the honeycomb limiting frame is 4-12 mm, and the diameter of the ceramic ball is 2-20 mm.

7. The densely packed ceramic ball reinforced metal matrix composite plate material according to claim 1, characterized in that: The gap between the adjacent ceramic balls in each layer is the sum of the wall thickness of the honeycomb limit frame and the assembly gap, which is 0.1-2 mm. The intervals between adjacent ceramic balls in the vertical direction are 2-8 mm.

8. A method for preparing a densely packed ceramic ball reinforced metal matrix composite plate, characterized in that: The method for preparing the densely packed ceramic ball reinforced metal matrix composite plate according to any one of claims 1 to 7 comprises the following steps: Step 1: Dimension design: According to the selected ceramic ball diameter, determine the side length and hole depth of the hexagonal through hole of the honeycomb limit frame in proportion, and determine the length and width of the honeycomb limit frame according to the sample size; Step 2: Pretreatment of the ceramic ball surface: remove impurities on the ceramic ball surface, plate a layer of copper, nickel or silver on the ceramic ball surface, wash and dry the plated ceramic ball; Step 3, powder laying and ceramic ball assembly: place a honeycomb limit frame on the metal back plate, lay a layer of metal powder in each hexagonal through hole, then fill a matching layer of ceramic balls into the hexagonal through holes, and then fill the metal powder to complete the construction of the first layer; if more than one layer of ceramic balls needs to be filled, place another honeycomb limit frame on the first layer and repeat the steps of laying metal powder and filling ceramic balls similar to the first layer; after all the layers are built, cover the last layer with a metal back plate, constrain the surroundings of the entire structure with steel plates, and fill the gap between the honeycomb limit frame and the constraining steel plate with metal powder; Step 4: Hot pressing and sintering: The above structures are bonded together by hot pressing and sintering to form a ceramic ball reinforced metal matrix composite plate.

9. The method for preparing the densely packed ceramic ball reinforced metal matrix composite plate according to claim 8, characterized in that: When performing the step 2, the ceramic ball is placed in a solution containing 50 to 75% by volume of ethanol and subjected to ultrasonic treatment for 15 to 40 minutes to remove surface impurities, and a layer of copper, nickel or silver is plated on the surface of the ceramic ball by chemical plating. The metal-plated ceramic ball is placed in deionized water or anhydrous ethanol for washing 2 to 4 times, and placed in an oven for drying at 105 to 120° C. for 30 to 120 minutes.

10. The method for preparing the densely packed ceramic ball reinforced metal matrix composite plate according to claim 8, characterized in that: When performing the step four, a layer of graphite paper is placed above, below, and on the left and right sides of the mold and the plate to be sintered, and the assembled plate to be sintered is placed in the corresponding mold. When the vacuum degree reaches 0.001-1Pa, heating and pressure sintering are started, and the heating rate is 2-15°C / min. The sintering temperature is 100-500°C below the melting point of the metal powder. When the sample temperature drops below 60°C, the vacuum is broken, the furnace door is opened, the sample is taken out of the mold, and the graphite paper on the surface of the sample is removed.

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