Nitride composite ceramic material and near-net forming preparation method thereof

Abstract

The invention relates to a nitride composite ceramic material and a near-net forming preparation method thereof, the nitride composite ceramic material comprises a (AlN) b (BN) c (M), M is a sintering aid, a, b and c are mass fractions, 39 < = a < = 55, 44 < = b < = 60, 1 < = c < = 7, and a + b + c = 100.

Description

Technical Field

[0001] The present invention relates to the field of machinable composite ceramics for electronic components, and in particular to a nitride composite ceramic material and a near-net-shape preparation method thereof. Background Art

[0002] Radars have an urgent need for high power, low loss, and fast switching of receiver front-end protection switches. Ferrite switches are required to have the characteristics of high power, low power consumption, and fast switching. Some complete machines require ferrite switches to withstand peak power ≥1kW, average power ≥200W, and switching time ≤100μs.

[0003] The primary factor affecting switching time is eddy currents in the cavity. Traditional ferrite switch cavities are made of metal materials with good thermal and electrical conductivity. During magnetic field transitions, these metals generate induced eddy currents, which typically cause switching times to be in the millisecond range. Therefore, it is necessary to research low-eddy-current materials with high electrical resistance and good thermal conductivity to replace existing metal materials and suppress these eddy currents.

[0004] The ideal eddy current suppression cavity is made of high-resistance materials. Since the waveguide cavity has high requirements for dimensional accuracy and surface quality, the cavity manufacturing material is required to have good machinability, that is, the cavity material should have high toughness to meet the high dimensional precision machining requirements of the cavity. The material's precision machinability and eddy current suppression are difficult to reconcile. Selecting appropriate low-hardness, high-toughness machinable ceramics is a key technology that must be overcome in high-power fast-switching ferrite switches. The material properties must meet the following three points: Material resistivity ≥10 2 Ωm, material thermal conductivity ≥30W / mK, material hardness ≤10GPa.

[0005] Structural ceramic materials represented by alumina and aluminum nitride have high resistivity (>10 5 Ωm), the eddy currents generated during rapid switching are low, and the material has a certain thermal conductivity. However, due to the directional nature of covalent bonds, the difficulty of dislocation slip, the high hardness and low fracture toughness of ceramic materials, it is difficult to precisely machine cavities and threaded holes through machining methods such as turning and milling. Machinability, high thermal conductivity, and low eddy currents are difficult to achieve simultaneously in conventional structural ceramic materials.

[0006] In addition, conventional ceramic materials are generally sintered into regular blocks, and ceramic cavities need to be processed based on the blocks, which requires a large amount of processing. While developing ceramic materials that can be precisely processed, it is also urgent to develop methods for near-net-shape forming of ceramics that can directly sinter blank materials with complex cavities and screw hole shapes. Summary of the Invention

[0007] In order to solve one or more technical problems existing in the prior art, the present invention provides a nitride composite ceramic material and a near-net-shape preparation method thereof.

[0008] The technical solution of the present invention to solve the above technical problems is as follows: a nitride composite ceramic material, the components of the nitride composite ceramic material include a(AlN)b(BN)c(M), wherein M is a sintering aid, a, b, and c are mass fractions, 39≤a≤55, 44≤b≤60, 1≤c≤7, and a+b+c=100.

[0009] The beneficial effects of the present invention are as follows: the nitride composite ceramic material of the present invention is a composite of aluminum nitride and boron nitride. The aluminum nitride and boron nitride composite material forms a special layered structure during the sintering process, which effectively hinders the rapid expansion of cracks inside the ceramic and improves the toughness of the material; the softer layered boron nitride phase can reduce the hardness of the composite material; the increase in toughness and the decrease in hardness make it different from conventional hard and brittle ceramic materials, and have excellent machinability; the phonon transmission characteristics of aluminum nitride also ensure that the composite ceramic has a higher thermal conductivity.

[0010] On the basis of the above technical solution, the present invention can also be improved as follows.

[0011] Further, a=47.5, b=47.5, c=5; or a=49, b=49, c=2; or a=55, b=44, c=1; or a=39, b=60, c=1.

[0012] The beneficial effect of adopting the above further solution is that the composite material with this ratio can simultaneously have the characteristics of low hardness and high toughness, and has a relatively low sintering temperature.

[0013] Furthermore, the components of M include one or more of Y2O3, CaCO3 and MgO.

[0014] Furthermore, the components of M include x(Y2O3)y(CaCO3)z(MgO), where x, y, and z are mass fractions, wherein 50≤x≤100, 0≤y≤30, 0≤z≤50, and x+y+z=100.

[0015] Further, x=100, y=0, z=0; or, x=50, y=20, z=30.

[0016] The beneficial effects of adopting the above further solution are: the sintering temperature can be reduced to below 1900° C., and the density of the sintered material is not less than 97%.

[0017] A near-net-shape preparation method for a nitride composite ceramic material comprises the following steps:

[0018] S1, preparing a casting slurry, and casting the slurry into a green ceramic sheet;

[0019] S2, laser processing the green ceramic sheet, forming prefabricated screw holes and cavity patterns on the green ceramic sheet by laser cutting, and marking cutting lines on the top green ceramic sheet by laser;

[0020] S3, laminating green ceramic sheets with prefabricated screw holes and cavity patterns layer by layer, placing the inlay mold into the screw hole cavities and outer shape cavities formed by laminating the green ceramic sheets, sealing and isostatically laminating, to form a ferrite switch cavity green body;

[0021] S4, hot-cutting the laminated ferrite switch cavity green body according to the cutting line mark position to obtain a hot-cut green body;

[0022] S5, placing the hot-cut green body in a closed boron nitride sagger, and sintering it in a gas pressure sintering furnace to form a ferrite switch blank;

[0023] S6, performing subsequent processing on the ferrite switch blank to obtain a ferrite switch waveguide cavity.

[0024] The beneficial effect of the present invention is that the method of the present invention does not require large-scale complex mechanical processing with a high aspect ratio, and can meet the size requirements of the cavity through only a small amount of surface finishing, while further reducing the processing difficulty and improving the qualified rate of sample processing.

[0025] Further, in S1, preparing the tape casting slurry includes selecting ceramic powders with a raw material purity of not less than 99.9%, wherein the ceramic powders include AlN powder, BN powder, Y2O3 powder, CaCO3 powder, and MgO powder, and the average particle size D50 of each powder is between 0.8 μm and 3.0 μm;

[0026] A casting slurry was prepared according to the mass ratio of ceramic powder: ethyl acetate: butyl acetate: tributyl phosphate: polyvinyl butyral resin: dioctyl phthalate = 100:25:25:2:7.5:3.

[0027] The beneficial effects of adopting the above further scheme are: by optimizing the type and ratio of the dispersant, a lower viscosity can be achieved at a higher solid content, and by optimizing the content of the polyvinyl butyral resin and the ratio of the polyvinyl butyral resin to dioctyl phthalate, sufficient bonding strength between the layers of the green porcelain is ensured during lamination to form it into a whole.

[0028] Furthermore, in S1, the thickness of the green ceramic sheet is 505 μm±30 ​​μm.

[0029] Furthermore, in S2, the processing power of the laser processing is 4 to 6 W, the pulse frequency of the laser processing is 60 to 80 kHz, and the laser cutting speed is 800 mm / s.

[0030] Furthermore, in S3, the lamination temperature of the isostatic lamination is 55° C. to 75° C., the pressure is 500 to 1200 psi, and the holding time is 8 to 15 minutes;

[0031] In S4, the hot cutting temperature is 60°C to 70°C;

[0032] In S5, placing in a gas pressure sintering furnace for sintering includes placing in a gas pressure sintering furnace, sintering at 1800° C. to 1900° C. for 4 to 6 hours in a nitrogen atmosphere of 1 to 4 MPa to form a ferrite switch blank;

[0033] In S6, subsequent processing includes surface finishing such as surface grinding and milling, threaded hole processing, and surface metallization such as sputtering primer and electroplating gold.

[0034] The beneficial effect of adopting the above further scheme is: through the composition design of aluminum nitride boron nitride composite ceramics, the requirements of high power fast switching ferrite switch cavity material of high resistance, low eddy current, high thermal conductivity, low hardness, high toughness and machinability are met, and the material resistivity is ≥10 2 Ωm, material thermal conductivity ≥30W / mK, material hardness ≤10GPa, meeting the ferrite switch's requirements of withstanding peak power ≥1kW, withstanding average power ≥200W, and switching time ≤100μs. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 Schematic diagram of the top view of the ferrite switch waveguide cavity of the present invention;

[0036] Figure 2 Schematic diagram of the split structure of the inlay mold of the present invention, which cooperates with the screw hole cavity and the outer shape cavity Figure 1 ;

[0037] Figure 3 This is a schematic structural diagram of the top raw ceramic sheet of the present invention;

[0038] Figure 4 Schematic diagram of the split structure of the inlay mold of the present invention, which cooperates with the screw hole cavity and the outer shape cavity Figure 2 ;

[0039] Figure 5 This is a schematic diagram of the structure of placing the hot-cut green body in a closed boron nitride sagger according to the present invention.

[0040] In the accompanying drawings, the components represented by the reference numerals are as follows:

[0041] 1. Screw hole cavity; 11. Prefabricated screw hole; 2. First-level step cavity; 21. Cavity pattern; 3. Second-level step cavity; 4. Through cavity; 5. Inlay mold; 6. Top layer of raw porcelain tile; 61. Cutting line; 62. Second layer of raw porcelain tile; 63. Third layer of raw porcelain tile; 64. Fourth layer of raw porcelain tile; 65. Fifth layer of raw porcelain tile; 66. Sixth layer of raw porcelain tile; 67. Seventh layer of raw porcelain tile; 68. Eighth layer of raw porcelain tile; 69. Ninth layer of raw porcelain tile; 690. Tenth layer of raw porcelain tile; 7. Malan film; 8. Boron nitride sagger. DETAILED DESCRIPTION

[0042] The principles and features of the present invention are described below with reference to the accompanying drawings. The examples given are only used to explain the present invention and are not used to limit the scope of the present invention.

[0043] Example 1

[0044] The components of the nitride composite ceramic material described in this embodiment include a(AlN)b(BN)c(M), where a=47.5, b=47.5, c=5, and the composition of M is x(Y2O3)y(CaCO3)z(MgO), where x=100, y=0, and z=0.

[0045] The near-net-shape preparation method of the nitride composite ceramic material comprises the following steps:

[0046] Preparation of green porcelain slurry: Select AlN, BN, and Y2O3 powders with a raw material purity of not less than 99.9%, and the average particle size (D50) of each powder is between 0.8 and 3.0 μm (the powder particle size selected in the following examples is the same as that in Example 1).

[0047] A casting slurry was prepared according to the mass ratio of ceramic powder: ethyl acetate: butyl acetate: tributyl phosphate: polyvinyl butyral resin: dioctyl phthalate = 100:25:25:2:7.5:3.

[0048] Green porcelain casting: The slurry is cast into green porcelain sheets, the thickness of which is generally 505±30μm.

[0049] Processing size design: According to the cavity design size, convert the green porcelain sintering shrinkage rate, and reserve processing allowance to design the shape and size of each layer of green porcelain cavity processing.

[0050] Laser cavity punching: (the total number of raw porcelain layers required and the processing pattern of each layer of raw porcelain are based on the cavity design, which is only used as an example here) cavity patterns 21 are cut by laser on 1 to 10 layers of raw porcelain sheets, and cutting lines 61 are marked on the topmost layer of raw porcelain sheet 6 by laser, wherein prefabricated screw holes 11 and a first-step cavity 2 are processed on the topmost layer of raw porcelain sheet 6, and cutting lines 61 are marked, prefabricated screw holes 11 and a first-step cavity 2 are processed on the second layer of raw porcelain sheet 62 and the third layer of raw porcelain sheet 63, a first-step cavity 2 is processed on the fourth layer of raw porcelain sheet 64 and the fifth layer of raw porcelain sheet 65, a second-step cavity 3 is processed on the sixth layer of raw porcelain sheet 66, the seventh layer of raw porcelain sheet 67 and the eighth layer of raw porcelain sheet 68, and a through cavity 4 is processed on the ninth layer of raw porcelain sheet 69 and the tenth layer of raw porcelain sheet 690. The laser cutting and marking processing method is ultraviolet laser processing, the processing power is 5W, the laser processing pulse frequency is 70kHz, and the laser cutting speed is 800mm / s.

[0051] Inlay material molding: Use organic glass tooling to pour the film, and use two-component silicone to prepare the inlay mold for the outer cavity during the lamination process, which serves as the supporting material for the outer cavity during the lamination process.

[0052] Lamination: The green ceramic sheets are laminated layer by layer in the order of the 10th layer to the 1st layer. A plurality of prefabricated screw holes 11 are stacked to form a screw hole cavity 1. A plurality of first-level step cavities 2, a plurality of second-level step cavities 3 and a plurality of through cavities 4 are stacked to form a total cavity. Figure 2 As shown; on the topmost raw porcelain sheet 6, a Malan film 7 is placed after processing the cavity, the inlay mold 5 is placed, and then the whole is placed in a vacuum bag, and the vacuum bag is sealed using a vacuum sealing machine to obtain a sealed green body;

[0053] Lamination: The sealed blank is subjected to warm isostatic pressing with a lamination pressure of 500 psi and a lamination temperature of 70°C. The lamination is performed after preheating for 5 minutes and holding pressure for 10 minutes. After lamination, the inlay mold is removed to form a full-plate ferrite switch cavity green body.

[0054] Hot cutting: Place the laminated genuine blank on a 70℃ hot plate for 5 minutes, then use a hot cutting machine to cut the blank along the cutting line in the XY direction to form a hot-cut green blank, that is, a single ferrite switch cavity green blank.

[0055] Sintering: Place the hot-cut green body in a boron nitride sagger 8, cover the sagger cover, place it in a vertical sintering furnace, flush with high-pressure nitrogen (2MPa), and sinter at a peak temperature of 1850℃ for 5h to make a ferrite switch cavity blank with a shape close to the design. It only needs a small amount of surface processing (such as surface grinding and milling) and surface metallization (such as sputtering primer and electroplating gold) to become a ferrite switch waveguide cavity.

[0056] Material performance test: Test the performance of the calcined material. The thermal conductivity of the material is 47W / mK and the resistivity is 4.04*10 16 Ωm, and a hardness of 2.1GPa. The composition ratio of the calcined material is consistent with that of the ferrite switch waveguide cavity, but the cavity does not require laser processing. Instead, it only needs to be laminated and hot-cut to directly produce a green compact of a specific shape, which is then sintered simultaneously with the single ferrite switch cavity green compact.

[0057] Example 2

[0058] The components of the nitride composite ceramic material described in this embodiment include a(AlN)b(BN)c(M), where a=49, b=49, c=2, and the composition of M is x(Y2O3)y(CaCO3)z(MgO), where x=50, y=20, and z=30.

[0059] The near-net-shape preparation method of the nitride composite ceramic material comprises the following steps:

[0060] Preparation of green porcelain slurry: Select AlN, BN, Y2O3, CaCO3, and MgO powders with a purity of at least 99.9%, and an average particle size (D50) of 0.8 to 3.0 μm for each powder. Prepare a tape casting slurry using a mass ratio of ceramic powder: ethyl acetate: butyl acetate: tributyl phosphate: polyvinyl butyral resin: dioctyl phthalate (DOP) = 100:25:25:2:7.5:3.

[0061] Green porcelain casting: The slurry is cast into green porcelain sheets, the thickness of which is generally 505±30μm.

[0062] Processing size design: According to the cavity design size, convert the green porcelain sintering shrinkage rate, and reserve processing allowance to design the shape and size of each layer of green porcelain cavity processing.

[0063] Laser cavity punching: (the total number of raw porcelain layers required and the processing pattern of each layer of raw porcelain are based on the cavity design, and are only used as an example here) cavity patterns 21 are cut by laser on 1 to 10 layers of raw porcelain sheets, and cutting lines 61 are marked on the topmost layer of raw porcelain sheet 6 by laser, wherein prefabricated screw holes 11 and a first-step cavity 2 are processed on the topmost layer of raw porcelain sheet 6, and cutting lines 61 are marked, prefabricated screw holes 11 and a first-step cavity 2 are processed on the second layer of raw porcelain sheet 62 and the third layer of raw porcelain sheet 63, a first-step cavity 2 is processed on the fourth layer of raw porcelain sheet 64 and the fifth layer of raw porcelain sheet 65, a second-step cavity 3 is processed on the sixth layer of raw porcelain sheet 66, the seventh layer of raw porcelain sheet 67 and the eighth layer of raw porcelain sheet 68, and a through cavity 4 is processed on the ninth layer of raw porcelain sheet 69 and the tenth layer of raw porcelain sheet 690. The laser cutting and marking processing method is ultraviolet laser processing, the processing power is 6W, the laser processing pulse frequency is 60kHz, and the laser cutting speed is 800mm / s.

[0064] Inlay material molding: Use organic glass tooling to pour the mold, and use two-component silicone to prepare the inlay mold 5 for the outer cavity during the lamination process, which serves as the supporting material for the outer cavity during the lamination process.

[0065] Lamination: The green ceramic sheets are laminated layer by layer in the order of the 10th layer to the 1st layer. A plurality of prefabricated screw holes 11 are stacked to form a screw hole cavity 1. A plurality of first-level step cavities 2, a plurality of second-level step cavities 3 and a plurality of through cavities 4 are stacked to form a total cavity. Figure 2 As shown; on the topmost raw porcelain sheet 6, a Malan film 7 is placed after processing the cavity, the inlay mold 5 is placed, and then the whole is placed in a vacuum bag, and the vacuum bag is sealed using a vacuum sealing machine to obtain a sealed green body;

[0066] Lamination: The sealed blank is subjected to warm isostatic pressing with a lamination pressure of 500 psi and a lamination temperature of 70° C., preheated for 5 minutes, and maintained at pressure for 10 minutes. After lamination, the inlay mold 5 is removed to form a full-plate ferrite switch cavity green body.

[0067] Hot cutting: Place the laminated genuine blank on a 70℃ hot plate for 5 minutes, then use a hot cutting machine to cut the blank along the cutting line in the XY direction to form a hot-cut green blank, that is, a single ferrite switch cavity green blank.

[0068] Sintering: Place the hot-cut green body in a boron nitride sagger 8, cover the sagger cover, place it in a vertical sintering furnace, flush with high-pressure nitrogen (2MPa), and sinter at a peak temperature of 1850℃ for 5h to make a ferrite switch cavity blank with a shape close to the design. It only needs a small amount of surface processing (such as surface grinding and milling) and surface metallization (such as sputtering primer and electroplating gold) to become a ferrite switch waveguide cavity.

[0069] Material performance test: Test the performance of the calcined material. The thermal conductivity of the material is 45W / mK and the resistivity is 3.78*10 16 Ωm, and a hardness of 2.0GPa. The composition ratio of the calcined material is consistent with that of the ferrite switch waveguide cavity, but the cavity does not require laser processing. Instead, it only needs to be laminated and hot-cut to directly produce a green compact of a specific shape, which is then sintered simultaneously with the single ferrite switch cavity green compact.

[0070] Example 3

[0071] The components of the nitride composite ceramic material described in this embodiment include a(AlN)b(BN)c(M), where a=55, b=44, c=1, and the composition of M is x(Y2O3)y(CaCO3)z(MgO), where x=50, y=20, and z=30.

[0072] The near-net-shape preparation method of the nitride composite ceramic material comprises the following steps:

[0073] Preparation of green porcelain slurry: Select AlN, BN, Y2O3, CaCO3, and MgO powders with a purity of at least 99.9%, and an average particle size (D50) of 0.8 to 3.0 μm for each powder. Prepare a tape casting slurry using a mass ratio of ceramic powder: ethyl acetate: butyl acetate: tributyl phosphate: polyvinyl butyral resin: dioctyl phthalate (DOP) = 100:25:25:2:7.5:3.

[0074] Green porcelain casting: The slurry is cast into green porcelain sheets, the thickness of which is generally 505±30μm.

[0075] Processing size design: According to the cavity design size, convert the green porcelain sintering shrinkage rate, and reserve processing allowance to design the shape and size of each layer of green porcelain cavity processing.

[0076] Laser cavity punching: (the total number of raw porcelain layers required and the processing pattern of each layer of raw porcelain are based on the cavity design, and are only used as an example here) cavity patterns 21 are cut by laser on 1 to 10 layers of raw porcelain sheets, and cutting lines 61 are marked on the topmost layer of raw porcelain sheet 6 by laser, wherein prefabricated screw holes 11 and a first-step cavity 2 are processed on the topmost layer of raw porcelain sheet 6, and cutting lines 61 are marked, prefabricated screw holes 11 and a first-step cavity 2 are processed on the second layer of raw porcelain sheet 62 and the third layer of raw porcelain sheet 63, a first-step cavity 2 is processed on the fourth layer of raw porcelain sheet 64 and the fifth layer of raw porcelain sheet 65, a second-step cavity 3 is processed on the sixth layer of raw porcelain sheet 66, the seventh layer of raw porcelain sheet 67 and the eighth layer of raw porcelain sheet 68, and a through cavity 4 is processed on the ninth layer of raw porcelain sheet 69 and the tenth layer of raw porcelain sheet 690. The laser cutting and marking processing method is ultraviolet laser processing, the processing power is 4W, the pulse frequency of laser processing is 80kHz, and the laser cutting speed is 800mm / s.

[0077] Inlay material molding: Use organic glass tooling to pour the film, and use two-component silicone to prepare the inlay mold for the outer cavity during the lamination process, which serves as the supporting material for the outer cavity during the lamination process.

[0078] Lamination: The green ceramic sheets are laminated layer by layer in the order of the 10th layer to the 1st layer. A plurality of prefabricated screw holes 11 are stacked to form a screw hole cavity 1. A plurality of first-level step cavities 2, a plurality of second-level step cavities 3 and a plurality of through cavities 4 are stacked to form a total cavity. Figure 2 As shown; on the topmost raw porcelain sheet 6, a Malan film 7 is placed after processing the cavity, the inlay mold 5 is placed, and then the whole is placed in a vacuum bag, and the vacuum bag is sealed using a vacuum sealing machine to obtain a sealed green body;

[0079] Lamination: The sealed blank is subjected to warm isostatic pressing with a lamination pressure of 500 psi and a lamination temperature of 70°C. The lamination is performed after preheating for 5 minutes and holding pressure for 10 minutes. After lamination, the inlay mold is removed to form a full-plate ferrite switch cavity green body.

[0080] Hot cutting: Place the laminated genuine blank on a 70℃ hot plate for 5 minutes, then use a hot cutting machine to cut the blank along the cutting line in the XY direction to form a hot-cut green blank, that is, a single ferrite switch cavity green blank.

[0081] Sintering: Place the hot-cut green body in a boron nitride sagger 8, cover the sagger cover, place it in a vertical sintering furnace, flush with high-pressure nitrogen (2MPa), and sinter at a peak temperature of 1880℃ for 5h to make a ferrite switch cavity blank with a shape close to the design. It only needs a small amount of surface processing (such as surface grinding and milling) and surface metallization (such as sputtering primer and electroplating gold) to become a ferrite switch waveguide cavity.

[0082] Material performance test: Test the performance of the calcined material. The thermal conductivity of the material is 62W / mK and the resistivity is 5.94*10 16 Ωm, and a hardness of 3.1GPa. The composition ratio of the calcined material is consistent with that of the ferrite switch waveguide cavity, but the cavity does not require laser processing. Instead, it only needs to be laminated and hot-cut to directly produce a green compact of a specific shape, which is then sintered simultaneously with the single ferrite switch cavity green compact.

[0083] Example 4

[0084] The components of the nitride composite ceramic material described in this embodiment include a(AlN)b(BN)c(M), where a=39, b=60, c=1, and the composition of M is x(Y2O3)y(CaCO3)z(MgO), where x=50, y=20, and z=30.

[0085] The near-net-shape preparation method of the nitride composite ceramic material comprises the following steps:

[0086] Preparation of green porcelain slurry: Select AlN, BN, Y2O3, CaCO3, and MgO powders with a purity of at least 99.9%, and an average particle size (D50) of 0.8 to 3.0 μm for each powder. Prepare a tape casting slurry using a mass ratio of ceramic powder: ethyl acetate: butyl acetate: tributyl phosphate: polyvinyl butyral resin: dioctyl phthalate (DOP) = 100:25:25:2:7.5:3.

[0087] Green porcelain casting: The slurry is cast into green porcelain sheets, the thickness of which is generally 505±30μm.

[0088] Processing size design: According to the cavity design size, convert the green porcelain sintering shrinkage rate, and reserve processing allowance to design the shape and size of each layer of green porcelain cavity processing.

[0089] Laser cavity punching: (the total number of raw porcelain layers required and the processing pattern of each layer of raw porcelain are based on the cavity design, which is only used as an example here) cavity patterns 21 are cut by laser on 1 to 10 layers of raw porcelain sheets, and cutting lines 61 are marked on the topmost layer of raw porcelain sheet 6 by laser, wherein prefabricated screw holes 11 and a first-step cavity 2 are processed on the topmost layer of raw porcelain sheet 6, and cutting lines 61 are marked, prefabricated screw holes 11 and a first-step cavity 2 are processed on the second layer of raw porcelain sheet 62 and the third layer of raw porcelain sheet 63, a first-step cavity 2 is processed on the fourth layer of raw porcelain sheet 64 and the fifth layer of raw porcelain sheet 65, a second-step cavity 3 is processed on the sixth layer of raw porcelain sheet 66, the seventh layer of raw porcelain sheet 67 and the eighth layer of raw porcelain sheet 68, and a through cavity 4 is processed on the ninth layer of raw porcelain sheet 69 and the tenth layer of raw porcelain sheet 690. The laser cutting and marking processing method is ultraviolet laser processing, the processing power is 5W, the laser processing pulse frequency is 70kHz, and the laser cutting speed is 800mm / s.

[0090] Inlay material molding: Use organic glass tooling to pour the film, and use two-component silicone to prepare the inlay mold for the outer cavity during the lamination process, which serves as the supporting material for the outer cavity during the lamination process.

[0091] Lamination: The green ceramic sheets are laminated layer by layer in the order of the 10th layer to the 1st layer. A plurality of prefabricated screw holes 11 are stacked to form a screw hole cavity 1. A plurality of first-level step cavities 2, a plurality of second-level step cavities 3 and a plurality of through cavities 4 are stacked to form a total cavity. Figure 2 As shown; on the topmost raw porcelain sheet 6, a Malan film 7 is placed after processing the cavity, the inlay mold 5 is placed, and then the whole is placed in a vacuum bag, and the vacuum bag is sealed using a vacuum sealing machine to obtain a sealed green body;

[0092] Lamination: The sealed blank is subjected to warm isostatic pressing with a lamination pressure of 500 psi and a lamination temperature of 70°C. The lamination is performed after preheating for 5 minutes and holding pressure for 10 minutes. After lamination, the inlay mold is removed to form a full-plate ferrite switch cavity green body.

[0093] Hot cutting: Place the laminated genuine blank on a 70℃ hot plate for 5 minutes, then use a hot cutting machine to cut the blank along the cutting line in the XY direction to form a hot-cut green blank, that is, a single ferrite switch cavity green blank.

[0094] Sintering: Place the hot-cut green body in a boron nitride sagger 8, cover the sagger cover, place it in a vertical sintering furnace, flush with high-pressure nitrogen (2MPa), and sinter at a peak temperature of 1880℃ for 5h to make a ferrite switch cavity blank with a shape close to the design. It only needs a small amount of surface processing (such as surface grinding and milling) and surface metallization (such as sputtering primer and electroplating gold) to become a ferrite switch waveguide cavity.

[0095] Material performance test: Test the performance of the calcined material. The thermal conductivity of the material is 48W / mK and the resistivity is 5.73*10 16 Ωm, and a hardness of 1.5GPa. The composition ratio of the calcined material is consistent with that of the ferrite switch waveguide cavity, but the cavity does not require laser processing. Instead, it only needs to be laminated and hot-cut to directly produce a green compact of a specific shape, which is then sintered simultaneously with the single ferrite switch cavity green compact.

[0096] In the description of this specification, the reference terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and features of different embodiments or examples without contradiction.

[0097] Although the embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. A nitride composite ceramic material, characterized in that: The components of the nitride composite ceramic material include a(AlN)b(BN)c(M), wherein M is a sintering aid, a, b, and c are mass fractions, 39≤a≤55, 44≤b≤60, 1≤c≤7, and a+b+c=100.

2. The nitride composite ceramic material according to claim 1, characterized in that: a=47.5, b=47.5, c=5; or a=49, b=49, c=2; or a=55, b=44, c=1; or a=39, b=60, c=1.

3. The nitride composite ceramic material according to claim 1, characterized in that: The components of M include one or more of Y2O3, CaCO3 and MgO.

4. The nitride composite ceramic material according to claim 3, characterized in that: The components of M include x(Y2O3)y(CaCO3)z(MgO), where x, y, and z are mass fractions, wherein 50≤x≤100, 0≤y≤30, 0≤z≤50, and x+y+z=100.

5. The nitride composite ceramic material according to claim 4, characterized in that: x=100, y=0, z=0; or, x=50, y=20, z=30.

6. A near-net-shape preparation method of the nitride composite ceramic material according to any one of claims 1 to 5, characterized in that: The following steps are involved: S1, preparing a casting slurry, and casting the slurry into a green ceramic sheet; S2, laser processing the green ceramic sheet, forming prefabricated screw holes and cavity patterns on the green ceramic sheet by laser cutting, and marking cutting lines on the top green ceramic sheet by laser; S3, laminating green ceramic sheets with prefabricated screw holes and cavity patterns layer by layer, placing the inlay mold into the screw hole cavities and outer shape cavities formed by laminating the green ceramic sheets, sealing and isostatically laminating, to form a ferrite switch cavity green body; S4, hot-cutting the laminated ferrite switch cavity green body according to the cutting line mark position to obtain a hot-cut green body; S5, placing the hot-cut green body in a closed boron nitride sagger, and sintering it in a gas pressure sintering furnace to form a ferrite switch blank; S6, performing subsequent processing on the ferrite switch blank to obtain a ferrite switch waveguide cavity.

7. The near-net shape preparation method according to claim 6, characterized in that: In S1, preparing the tape casting slurry includes selecting ceramic powders with a raw material purity of not less than 99.9%, wherein the ceramic powders include AlN powder, BN powder, Y2O3 powder, CaCO3 powder, and MgO powder, and the average particle size D50 of each powder is between 0.8 μm and 3.0 μm; A casting slurry was prepared according to the mass ratio of ceramic powder: ethyl acetate: butyl acetate: tributyl phosphate: polyvinyl butyral resin: dioctyl phthalate = 100:25:25:2:7.5:

3.

8. The near-net shape preparation method according to claim 6, characterized in that: In S1, the thickness of the green ceramic sheet is 505 μm ± 30 μm.

9. The near-net shape preparation method according to claim 6, characterized in that: In S2, the processing power of the laser processing is 4 to 6 W, the pulse frequency of the laser processing is 60 to 80 kHz, and the laser cutting speed is 800 mm / s.

10. The near-net shape preparation method according to claim 6, characterized in that: In S3, the lamination temperature of the isostatic lamination is 55°C to 75°C, the pressure is 500 to 1200 psi, and the holding time is 8 to 15 minutes; In S4, the hot cutting temperature is 60°C to 70°C; In S5, placing in a gas pressure sintering furnace for sintering includes placing in a gas pressure sintering furnace, sintering at 1800° C. to 1900° C. for 4 to 6 hours in a nitrogen atmosphere of 1 to 4 MPa to form a ferrite switch blank; In S6, subsequent processing includes surface finishing, threaded hole processing and surface metallization.

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