Layered structure silicon nitride ceramic antenna housing and integrated forming method

Abstract

The invention discloses a silicon nitride ceramic antenna housing with a layered structure and an integrated forming method. The integrated forming method of the silicon nitride ceramic antenna housing with the layered structure comprises the following steps: crushing and screening silicon nitride mixed powder blocks to obtain silicon nitride mixed powder; the first molding particles comprise paraffin and first thermoplastic resin; the second molding particles comprise second thermoplastic resin; carrying out primary glue discharging treatment on the silicon nitride ceramic green body with the layered structure in a second solvent to obtain a secondary silicon nitride ceramic green body with a layered structure; heating the secondary silicon nitride ceramic green body with the layered structure and carrying out secondary glue discharging treatment to obtain a silicon nitride ceramic green body with the layered structure; and sintering the silicon nitride ceramic green body with the layered structure to obtain the silicon nitride ceramic antenna housing with the layered structure. The bandwidth of the wave-transparent frequency of the radome is improved, the wave-transparent rate of the radome is not affected, and meanwhile the radome is high in strength.

Description

Technical Field

[0001] The present invention relates to the field of silicon nitride ceramic radomes, and in particular to the field of a layered silicon nitride ceramic radome and an integrated molding method. Background Art

[0002] The wave transmission performance of the radome is extremely important in the aerospace field. With the development of technology, in addition to requiring the radome to have high wave transmittance, it is also necessary to increase the bandwidth of the radome's wave transmission frequency.

[0003] The wave transmission frequency of a traditional radome is mainly determined by the dielectric constant of the material itself. Therefore, improving the bandwidth of the wave transmission frequency of the radome without affecting the wave transmittance of the radome and at the same time ensuring the high strength of the radome has become a difficult problem that needs to be solved urgently in this field. Summary of the Invention

[0004] The purpose of the present invention is to provide a layered silicon nitride ceramic antenna cover and an integrated molding method to improve the bandwidth of the wave transmission frequency of the antenna cover without affecting the wave transmittance of the antenna cover, while the antenna cover has high strength.

[0005] One aspect of the present invention provides a method for integrally forming a layered silicon nitride ceramic radome, comprising the following steps:

[0006] preparing a mixed ceramic powder, wherein the mixed ceramic powder comprises silicon nitride powder;

[0007] Mixing and grinding the mixed ceramic powder and the first solvent to prepare silicon nitride slurry;

[0008] heating the silicon nitride slurry at a first temperature to obtain a silicon nitride mixed powder block;

[0009] Grinding and sieving the silicon nitride mixed powder block to obtain a silicon nitride mixed powder;

[0010] preparing first molded particles and second molded particles by using silicon nitride mixed powder;

[0011] The first molded particles include paraffin wax and a first thermoplastic resin; the second molded particles include a second thermoplastic resin;

[0012] Using the first molded particles and the second molded particles to prepare a layered silicon nitride ceramic primary body through an FDM printer;

[0013] subjecting the layered silicon nitride ceramic body to a debinding treatment in a second solvent to obtain a secondary layered silicon nitride ceramic body;

[0014] heating the secondary layered silicon nitride ceramic body to perform a secondary binder removal treatment to obtain a layered silicon nitride ceramic body;

[0015] Sintering the layered silicon nitride ceramic body to obtain the layered silicon nitride ceramic antenna cover;

[0016] Preferably, in the process of preparing the layered silicon nitride ceramic primary body by FDM printer, the slice layer thickness is 0.2mm-1.5mm, the printing temperature is 140℃-180℃, and the printing speed is 40mm / s-60mm / s; further preferably, the slice layer thickness is 0.8mm-1.5mm;

[0017] Preferably, the layered silicon nitride ceramic body is integrally formed;

[0018] Preferably, the debinding process of the layered silicon nitride ceramic body in the second solvent comprises: soaking the layered silicon nitride ceramic body in the second solution at 40° C.-60° C. for 46-50 hours; then taking it out and drying it at 75-85° C. for 11.5-12.5 hours;

[0019] The second solvent includes one or more of kerosene, gasoline, diesel, toluene or ethane.

[0020] Preferably, the secondary debinding process of heating the secondary layered silicon nitride ceramic body comprises: placing the secondary layered silicon nitride ceramic body into a debinding furnace and heating it to 90-110°C at a heating rate of 9-10°C; heating it from 90-110°C to 220-260°C at a heating rate of 5-6°C; heating it from 220-260°C to 580-620°C at a heating rate of 3-4°C;

[0021] Preferably, the sintering process of the layered silicon nitride ceramic body includes the following steps: heating to 1300-1600°C at a rate of 1-5°C / min under a flow rate and atmosphere of 30-60sccmN2 and a pressure of 5-10MPa, and keeping warm at 1300-1600°C for 2-4h to obtain the layered silicon nitride ceramic antenna cover; thereby realizing the α-β phase transformation of silicon nitride.

[0022] The beneficial effect of the present invention over the prior art is that, by heating the silicon nitride slurry at a first temperature to obtain a silicon nitride mixed powder block; crushing and screening the silicon nitride mixed powder block to obtain a silicon nitride mixed powder, the silicon nitride mixed powder can be used to prepare a layered silicon nitride ceramic primary body by an FDM printer, and the material width of the printer outlet is large, so that each printed layer of the body can be composed of multiple material strips, thereby achieving different porosities at different positions of each layer of material;

[0023] Because the first molded particles include paraffin wax and a first thermoplastic resin, and the first molded particles include a second thermoplastic resin, the first molded particles and the second molded particles can be used to prepare a layered silicon nitride ceramic primary body using an FDM printer, and the first molded particles and the second molded particles have different porosities. This allows each layer of material to have different porosities at different locations, and the specific porosity relationship between different locations is controllable.

[0024] The layered silicon nitride ceramic radome is ultimately realized to include several layers of silicon nitride ceramic, each layer of which is connected in sequence in a vertical direction; and each layer of silicon nitride ceramic includes several first ceramic strips and second ceramic strips of different porosities connected according to preset positions; ultimately, when electromagnetic waves pass through the several layers of silicon nitride ceramic in sequence, the electromagnetic waves are propagated in each layer of silicon nitride ceramic according to different propagation media, and the ratio of electromagnetic waves propagating in different media is controllable, and the propagation time of electromagnetic waves in the medium can be widely controlled; then, by superimposing several layers of silicon nitride ceramic, it is ultimately realized that the same electromagnetic wave has more propagation paths when passing through the layered silicon nitride ceramic radome, and the propagation time of the electromagnetic wave in each path is different, thereby improving the bandwidth of the wave transmission frequency of the radome;

[0025] By performing a debinding treatment in the second solvent, it is beneficial to slowly extract some substances in the layered silicon nitride ceramic body, thereby forming a number of pores in the layered silicon nitride ceramic body. The pores are through holes, which are beneficial to the subsequent volatilization of the first thermoplastic resin and the improvement of the strength of the layered silicon nitride ceramic antenna cover.

[0026] Furthermore, the preparation process of the mixed ceramic powder includes the following steps: mixing α silicon nitride powder and a sintering aid in a mass ratio of silicon nitride powder (88-92): (7-13) to obtain the mixed ceramic powder;

[0027] The sintering aid comprises one or more of aluminum oxide, yttrium oxide, and lanthanum oxide. Preferably, the sintering aid comprises aluminum oxide, yttrium oxide, and lanthanum oxide in a mass ratio of (4-6): (2-5): (1-2).

[0028] Furthermore, the specific process of preparing silicon nitride slurry includes the following steps:

[0029] The mixed ceramic powder and the first solvent are mixed and ball-milled in a mass ratio of (8-12): (18-22) for 70-74 hours to obtain a silicon nitride slurry;

[0030] The first solvent is ethanol or methanol.

[0031] Furthermore, in the process of preparing the silicon nitride mixed powder block, the first temperature is 60° C. to 80° C., and the heating time is 20-26 hours.

[0032] Furthermore, the silicon nitride mixed powder includes a first silicon nitride mixed powder and a second silicon nitride mixed powder;

[0033] The process of preparing the first shaped particles comprises the following steps:

[0034] The first silicon nitride mixed powder, paraffin wax, and the first thermoplastic resin are heated and kneaded at 150° C. to 200° C. in a mass ratio of (78-83): (9-13): (6-9) for 1-2 hours; and then extruded and granulated at 130° C. to 180° C. and an extrusion pressure of 20 MPa to 35 MPa to obtain first molded particles with a particle size of 2-2.2 mm. The process for preparing the second molded particles comprises the following steps:

[0035] The second silicon nitride mixed powder, paraffin wax, and the second thermoplastic resin are heated and kneaded at 150° C.-180° C. in a mass ratio of (85-92): (3-7): (5-8) for 1-2 hours; then, the mixture is extruded and granulated at 130° C.-160° C. and an extrusion pressure of 20 MPa-35 MPa to obtain second molded particles with a particle size of 1-1.6 mm.

[0036] The beneficial effect of adopting the previous step is that, since the first molded particles include the first silicon nitride mixed powder, paraffin wax, and the first thermoplastic resin, and the paraffin wax and the first thermoplastic resin have high contents, the first ceramic strip obtained by sintering the first material strip prepared by the first molded particles has high porosity and large pore size, and when the layered silicon nitride ceramic body is subjected to a first debinding treatment in the second solvent, the paraffin wax first enters the second solvent from the first material strip, forming a through hole in the first ceramic strip, which is conducive to the subsequent volatilization of the first thermoplastic resin on the basis of the through hole during the secondary debinding treatment, thereby avoiding the problem of cracking or damage during the secondary debinding treatment;

[0037] The second molded particles include a first silicon nitride mixed powder, paraffin wax, and a second thermoplastic resin, and the paraffin wax and second thermoplastic resin have high contents. The second ceramic strip obtained after sintering the second material strip prepared by the second molded particles has low porosity and small pore size. When the layered silicon nitride ceramic body undergoes a primary debinding treatment in the second solvent, the paraffin wax first enters the second solvent from the second material strip, forming through holes in the second ceramic strip. This is conducive to the subsequent volatilization of the second thermoplastic resin on the basis of the through holes during the secondary debinding treatment, thereby avoiding the problem of cracking or damage during the secondary debinding treatment.

[0038] This ultimately results in ceramic strips with different porosities at different locations on the same silicon nitride ceramic.

[0039] Furthermore, the particle size of the first silicon nitride mixed powder is 30-60 mesh; the particle size of the second silicon nitride mixed powder is 50-60 mesh;

[0040] and / or

[0041] The first thermoplastic resin includes thermoplastic resin A and thermoplastic resin B; the first thermoplastic resin includes thermoplastic resin A;

[0042] The volatilization temperature of the thermoplastic resin A is 200-300°C; the volatilization temperature of the thermoplastic resin B is 300-500°C;

[0043] The thermoplastic resin A includes one or more of organic glass, acrylonitrile-butadiene-styrene copolymer (ABS), and ethylene-vinyl acetate copolymer (EVA);

[0044] The thermoplastic resin B includes one or more of high-density polyethylene, polypropylene, and polystyrene.

[0045] The beneficial effect of the above step is that the particle size of the second silicon nitride mixed powder is 50-60 mesh, which is conducive to improving the density of the second ceramic strip;

[0046] The first thermoplastic resin includes thermoplastic resin A and thermoplastic resin B; the volatilization temperature of thermoplastic resin A is 200-300°C; and the volatilization temperature of thermoplastic resin B is 300-500°C. During the second heat treatment of the first material strip, the thermoplastic resin A volatilizes on the basis of the pores formed by paraffin extraction, thereby forming pores with larger pore diameters, which are further conducive to the volatilization of thermoplastic resin B. As a result, the second ceramic strip has a high porosity, a large pore diameter, and relatively high strength, and is free from problems such as cracking or damage.

[0047] Because the first thermoplastic resin includes the thermoplastic resin A, the second ceramic strip has a small porosity and a small pore size.

[0048] Furthermore, the process of preparing the layered silicon nitride ceramic primary body comprises the following steps:

[0049] The FDM printer includes a first material outlet and a second material outlet; the first molded particles are heated and flow out of the first material outlet, and the second molded particles are heated and flow out of the second material outlet;

[0050] Printing process: Multi-layer printing according to 1-n layers, each layer is set in the horizontal direction, and the 1-n layers are connected in sequence in the vertical direction;

[0051] Each layer includes a plurality of first material strips and a plurality of second material strips; the first material strips and the second material strips are arranged horizontally at intervals; the first material strips and the second material strips are arranged in parallel;

[0052] The first material strip is arranged at an angle to the horizontal direction;

[0053] The first material passes through the first material outlet and prints the first material strip from top to bottom. Then the second material passes through the second material outlet and prints the second material strip from top to bottom. This is one cycle. Then, this cycle is repeated to form the first layer.

[0054] Then, a second layer is printed on top of the first layer, and then layers 3-n are printed in sequence to obtain the layered silicon nitride ceramic primary body;

[0055] Preferably, the ends of the first material strips of two adjacent layers are in contact.

[0056] By adopting the beneficial effects of the previous step, a layered silicon nitride ceramic primary body is realized, which includes several ceramic body layers, and each ceramic body layer is separated by an indirect first material strip and a second material strip; by setting the first material strip at an angle to the horizontal direction, it is beneficial for the electromagnetic wave to propagate at different times in the material strip when passing through the first material strip. When the electromagnetic wave enters the layered silicon nitride ceramic antenna cover vertically, the greater the angle, the longer the propagation time.

[0057] Furthermore, the angle between the first material strip of the nth layer and the horizontal direction is αn; the angles αn of two adjacent layers are different.

[0058] Furthermore, when n is an even number, the angle αn of the nth layer is <90°;

[0059] When n is an odd number, the angle of αn of the nth layer is > 90°;

[0060] or

[0061] When n is an even number, the angle of αn of the nth layer is > 90°;

[0062] When n is an odd number, the angle αn of the nth layer is less than 90°.

[0063] The beneficial effect of adopting the previous step is that when the electromagnetic wave enters the next silicon nitride ceramic layer from one silicon nitride ceramic layer, the problem of low probability of electromagnetic wave refraction in the next silicon nitride ceramic layer is avoided, thereby further improving the propagation time of the electromagnetic wave in the layered silicon nitride ceramic antenna cover.

[0064] In another aspect of the present invention, a layered silicon nitride ceramic radome is prepared by an integrated molding method of a layered silicon nitride ceramic radome;

[0065] The layered silicon nitride ceramic radome comprises 1-n layers of silicon nitride ceramic; each layer of silicon nitride ceramic is arranged in a horizontal direction, and the 1-n layers of silicon nitride ceramic are sequentially connected in a vertical direction;

[0066] Each layer of silicon nitride ceramic includes a plurality of first ceramic strips and a plurality of second ceramic strips; the first ceramic strips and the second ceramic strips are arranged horizontally and spaced apart from each other; the first ceramic strips and the second ceramic strips are arranged in parallel;

[0067] The first material strip is arranged at an angle to the horizontal direction;

[0068] The porosity of the first ceramic strip is 80-90%, and the porosity of the second ceramic strip is 10-20%;

[0069] The wave transmission performance of the layered silicon nitride ceramic radome is ≥75%;

[0070] The dielectric constant of the layered silicon nitride ceramic antenna cover is in the range of 2-4.

[0071] The beneficial effect of the present invention over the prior art is that each layer of the green body can be composed of a plurality of first ceramic strips and a plurality of second ceramic strips, thereby achieving different porosities at different positions of each layer of silicon nitride ceramic;

[0072] The first ceramic strip and the second ceramic strip have different porosities; thereby achieving different porosities at different positions of each layer of silicon nitride ceramic and controlling the size relationship of the porosities at different positions;

[0073] Ultimately, when the electromagnetic wave passes through several layers of silicon nitride ceramics in sequence, the electromagnetic wave propagates in each layer of silicon nitride ceramics according to different propagation media, and the ratio of electromagnetic waves propagating in different media is controllable, and the propagation time of the electromagnetic wave in the medium can be macroscopically controlled; then, by superimposing several layers of silicon nitride ceramics, it is finally achieved that the same electromagnetic wave has more propagation paths when passing through the layered silicon nitride ceramic antenna cover, and the propagation time of the electromagnetic wave in each path is different, thereby increasing the bandwidth of the wave transmission frequency of the antenna cover; and the layered silicon nitride ceramic antenna cover has high strength. DETAILED DESCRIPTION

[0074] In order to better understand the technical solution of the present invention, the present invention is further described below in conjunction with specific embodiments.

[0075] Example 1:

[0076] One aspect of this embodiment provides a method for integrally forming a layered silicon nitride ceramic radome, comprising the following steps:

[0077] Preparing a mixed ceramic powder, the mixed ceramic powder comprising silicon nitride powder; mixing α-silicon nitride powder and a sintering aid in a mass ratio of 90:10 to silicon nitride powder to obtain the mixed ceramic powder;

[0078] The sintering aid includes aluminum oxide, yttrium oxide, and lanthanum oxide, and the mass ratio of the aluminum oxide, yttrium oxide, and lanthanum oxide is 5:3.5:1.5.

[0079] The mixed ceramic powder and the first solvent are mixed and ground to prepare silicon nitride slurry. The specific process of preparing the silicon nitride slurry includes the following steps:

[0080] The mixed ceramic powder and the first solvent were mixed in a mass ratio of 10:20 and ball-milled for 72 hours to obtain silicon nitride slurry; the first solvent was ethanol.

[0081] The silicon nitride slurry is heated at a first temperature to obtain a silicon nitride mixed powder block; during the preparation of the silicon nitride mixed powder block, the first temperature is 70° C. and the heating time is 23 hours.

[0082] Crushing and sieving the silicon nitride mixed powder block to obtain a silicon nitride mixed powder; the silicon nitride mixed powder includes a first silicon nitride mixed powder and a second silicon nitride mixed powder;

[0083] First molded particles and second molded particles are prepared by using silicon nitride mixed powder. The process of preparing the first molded particles includes the following steps:

[0084] The first silicon nitride mixed powder, paraffin wax, and the first thermoplastic resin are heated and kneaded at 180° C. in a mass ratio of 80:11:7 for 1.5 hours; then, the mixture is extruded and granulated at 155° C. and an extrusion pressure of 28 MPa to obtain first molded particles with a particle size of 2.1 mm. The process for preparing the second molded particles comprises the following steps:

[0085] The second silicon nitride mixed powder, paraffin wax and the second thermoplastic resin were heated and kneaded at a mass ratio of 88:5:6 at 160° C. for 1.5 hours; then extruded and granulated at 145° C. and an extrusion pressure of 28 MPa to obtain second molded particles with a particle size of 1.3 mm.

[0086] The first molded particles include paraffin wax and a first thermoplastic resin; the second molded particles include a second thermoplastic resin; the particle size of the first silicon nitride mixed powder is 45 mesh; the particle size of the second silicon nitride mixed powder is 55 mesh;

[0087] The first thermoplastic resin includes thermoplastic resin A and thermoplastic resin B; the first thermoplastic resin includes thermoplastic resin A;

[0088] The volatilization temperature of the thermoplastic resin A is 200-300°C; the volatilization temperature of the thermoplastic resin B is 300-500°C;

[0089] Thermoplastic resin A includes acrylonitrile-butadiene-styrene copolymer (ABS);

[0090] Thermoplastic resin B includes high-density polyethylene.

[0091] A layered silicon nitride ceramic primary body is prepared using first and second molded particles using an FDM printer; the FDM printer includes a first material outlet and a second material outlet; the first molded particles are heated and flow out of the first material outlet, and the second molded particles are heated and flow out of the second material outlet; during the preparation of the layered silicon nitride ceramic primary body using the FDM printer, the slice thickness is 0.8 mm, the printing temperature is 160° C., and the printing speed is 50 mm / s;

[0092] Printing process: Multi-layer printing according to 1-n layers, each layer is set in the horizontal direction, and the 1-n layers are connected in sequence in the vertical direction;

[0093] Each layer includes a plurality of first material strips and a plurality of second material strips; the first material strips and the second material strips are arranged horizontally at intervals; the first material strips and the second material strips are arranged in parallel;

[0094] The first material strip is arranged at an angle to the horizontal direction;

[0095] The first material passes through the first material outlet and prints the first material strip from top to bottom. Then the second material passes through the second material outlet and prints the second material strip from top to bottom. This is one cycle. Then, this cycle is repeated to form the first layer.

[0096] Then, a second layer is printed on top of the first layer, and then layers 3-n are printed in sequence to obtain the layered silicon nitride ceramic primary body;

[0097] The angle between the first material strip of the nth layer and the horizontal direction is αn; the αn ​​of two adjacent layers is different.

[0098] When n is an even number, the angle of αn of the nth layer is less than 90°; when n is an odd number, the angle of αn of the nth layer is greater than 90°;

[0099] The layered silicon nitride ceramic body is subjected to a debinding treatment in a second solvent to obtain a secondary layered silicon nitride ceramic body; the layered silicon nitride ceramic body is subjected to a debinding treatment in the second solvent, the process comprising soaking the layered silicon nitride ceramic body in the second solution at 50°C for 48 hours; then taking it out and drying it at 80°C for 12 hours; the second solvent comprises kerosene and ethane.

[0100] The secondary layered silicon nitride ceramic body is heated to perform a secondary debinding treatment to obtain a layered silicon nitride ceramic body; the secondary layered silicon nitride ceramic body is heated to perform a secondary debinding treatment, comprising: placing the secondary layered silicon nitride ceramic body in a debinding furnace and heating it to 100° C. at a heating rate of 9.5° C.; heating it from 100° C. to 240° C. at a heating rate of 5.5° C.; and heating it from 240° C. to 600° C. at a heating rate of 3.5° C.;

[0101] The layered silicon nitride ceramic body is sintered to obtain the layered silicon nitride ceramic antenna cover; the layered silicon nitride ceramic body is integrally formed; the sintering process of the layered silicon nitride ceramic body includes the following steps: heating to 1450°C at a rate of 3°C / min under an N2 flow rate and atmosphere of 45sccm and a pressure of 8MPa, and maintaining the temperature at 1450°C for 3h.

[0102] Another aspect of this embodiment provides a layered silicon nitride ceramic radome prepared by an integrated molding method for a layered silicon nitride ceramic radome;

[0103] The layered silicon nitride ceramic radome comprises 1-n layers of silicon nitride ceramic; each layer of silicon nitride ceramic is arranged in a horizontal direction, and the 1-n layers of silicon nitride ceramic are sequentially connected in a vertical direction;

[0104] Each layer of silicon nitride ceramic includes a plurality of first ceramic strips and a plurality of second ceramic strips; the first ceramic strips and the second ceramic strips are arranged horizontally and spaced apart from each other; the first ceramic strips and the second ceramic strips are arranged in parallel;

[0105] The first material strip is arranged at an angle to the horizontal direction;

[0106] The porosity of the first ceramic strip is 85%, and the porosity of the second ceramic strip is 15%;

[0107] The wave transmission performance of the layered silicon nitride ceramic radome is ≥75%;

[0108] The dielectric constant of the layered silicon nitride ceramic antenna cover is in the range of 2-4.

[0109] Example 2:

[0110] The same contents as those in Example 1 are not described in detail here. The differences between this embodiment and Example 1 are as follows:

[0111] One aspect of this embodiment provides a method for integrally forming a layered silicon nitride ceramic radome, comprising the following steps:

[0112] Mixing α-silicon nitride powder and a sintering aid in a mass ratio of 89:8 to obtain the mixed ceramic powder;

[0113] The sintering aids include aluminum oxide, yttrium oxide, and lanthanum oxide;

[0114] The sintering aid includes aluminum oxide, yttrium oxide and lanthanum oxide in a mass ratio of 4.5:2.5:1.2.

[0115] The mixed ceramic powder and the first solvent were mixed in a mass ratio of 9:19 and ball-milled for 71 hours to obtain silicon nitride slurry.

[0116] During the preparation of the silicon nitride mixed powder block, the first temperature is 605° C. and the heating time is 21 hours.

[0117] The first silicon nitride mixed powder, paraffin wax, and the first thermoplastic resin were heated and kneaded at 170° C. in a mass ratio of 79:9.5:6.5 for 1.2 hours; and then extruded and granulated at 140° C. and an extrusion pressure of 25 MPa to obtain first molded particles;

[0118] The process of preparing the second shaped particles comprises the following steps:

[0119] The second silicon nitride mixed powder, paraffin wax, and the second thermoplastic resin were heated and kneaded at a mass ratio of 86:4:6 at 165° C. for 1.2 hours; then, the mixture was extruded and granulated at 135° C. and an extrusion pressure of 25 MPa to obtain second molded particles with a particle size of 1.2 mm.

[0120] The first molded particles include paraffin wax and a first thermoplastic resin; the second molded particles include a second thermoplastic resin; the particle size of the first silicon nitride mixed powder is 50 mesh; the particle size of the second silicon nitride mixed powder is 53 mesh;

[0121] Thermoplastic resin A includes organic glass and acrylonitrile-butadiene-styrene copolymer (ABS);

[0122] Thermoplastic resin B includes polypropylene and polystyrene.

[0123] During the process of preparing a layered silicon nitride ceramic primary body using an FDM printer, the slice layer thickness was 1.1 mm, the printing temperature was 150° C., and the printing speed was 45 mm / s; the ends of the first material strips of two adjacent layers were in contact;

[0124] When n is an even number, the angle αn of the nth layer is greater than 90°;

[0125] When n is an odd number, the angle αn of the nth layer is less than 90°.

[0126] The layered silicon nitride ceramic body is immersed in a second solution at 45° C. for 49 hours, and then taken out and dried at 76° C. for 12.2 hours. The second solvent includes toluene or ethane.

[0127] The secondary layered silicon nitride ceramic body was placed in a binder removal furnace and heated to 95°C at a heating rate of 9.2°C; then heated from 95°C to 230°C at a heating rate of 5.2°C; and then heated from 230°C to 590°C at a heating rate of 3.2°C.

[0128] The sintering process of the layered silicon nitride ceramic body includes the following steps: heating to 1350° C. at a rate of 2° C. / min under a 35 sccm N2 flow rate and atmosphere and a pressure of 6 MPa, and maintaining the temperature at 1350° C. for 3.5 hours.

[0129] Another aspect of this embodiment provides a layered silicon nitride ceramic radome prepared by an integrated molding method for a layered silicon nitride ceramic radome;

[0130] The porosity of the first ceramic strip is 88%, and the porosity of the second ceramic strip is 17%.

[0131] Example 3:

[0132] The same contents as those in Example 1 are not described in detail here. The differences between this embodiment and Example 1 are as follows:

[0133] One aspect of this embodiment provides a method for integrally forming a layered silicon nitride ceramic radome, comprising the following steps:

[0134] Mixing α-silicon nitride powder and a sintering aid in a mass ratio of 91:12 to obtain the mixed ceramic powder;

[0135] The sintering aid includes alumina.

[0136] The mixed ceramic powder and the first solvent were mixed in a mass ratio of 11:21 and ball-milled for 73 hours to obtain a silicon nitride slurry; the first solvent was methanol.

[0137] During the preparation of the silicon nitride mixed powder block, the first temperature is 78° C. and the heating time is 22 hours.

[0138] The first silicon nitride mixed powder, paraffin wax, and the first thermoplastic resin were heated and kneaded at 190° C. in a mass ratio of 92:6:7 for 1.8 hours; and then extruded and granulated at 160° C. and an extrusion pressure of 33 MPa to obtain first molded particles.

[0139] The process of preparing the second shaped particles comprises the following steps:

[0140] The second silicon nitride mixed powder, paraffin wax, and the second thermoplastic resin were heated and kneaded at a mass ratio of 82:12:8 at 170° C. for 1.8 hours; then, the mixture was extruded and granulated at 150° C. and an extrusion pressure of 31 MPa to obtain second molded particles with a particle size of 1.5 mm.

[0141] The first molded particles include paraffin wax and a first thermoplastic resin; the second molded particles include a second thermoplastic resin; the particle size of the first silicon nitride mixed powder is 58 mesh; the particle size of the second silicon nitride mixed powder is 51 mesh;

[0142] Thermoplastic resin A includes ethylene-vinyl acetate copolymer; thermoplastic resin B includes polystyrene.

[0143] During the process of preparing a layered silicon nitride ceramic primary body using an FDM printer, the slice layer thickness was 1.3 mm, the printing temperature was 170° C., and the printing speed was 46 mm / s; the ends of the first material strips of two adjacent layers were in contact;

[0144] When n is an even number, the angle αn of the nth layer is greater than 90°;

[0145] When n is an odd number, the angle αn of the nth layer is less than 90°.

[0146] The layered silicon nitride ceramic body is immersed in a second solution at 58° C. for 47 hours, and then taken out and dried at 83° C. for 11.8 hours. The second solvent includes toluene.

[0147] The secondary layered silicon nitride ceramic body was placed in a binder removal furnace and heated to 109°C at a heating rate of 9.8°C; then heated from 109°C to 255°C at a heating rate of 5.8°C; and then heated from 255°C to 610°C at a heating rate of 3.8°C.

[0148] The sintering process of the layered silicon nitride ceramic body includes the following steps: heating to 1550° C. at a rate of 4.6° C. / min under a N2 flow rate of 55 sccm and an atmosphere at a pressure of 9 MPa, and maintaining the temperature at 1550° C. for 2.5 hours.

[0149] Another aspect of this embodiment provides a layered silicon nitride ceramic radome prepared by an integrated molding method for a layered silicon nitride ceramic radome;

[0150] The porosity of the first ceramic strip is 83%, and the porosity of the second ceramic strip is 12%.

[0151] The above description is merely a preferred embodiment of the present application and an illustration of the technical principles employed. Those skilled in the art should understand that the scope of the invention herein is not limited to the technical solutions formed by the specific combination of the above-mentioned technical features, but also encompasses other technical solutions formed by any combination of the above-mentioned technical features or their equivalents without departing from the inventive concept. For example, the above-mentioned features may have similar functions to (but not limited to) those disclosed in this application.

Claims

1. A method for integrally forming a layered silicon nitride ceramic radome, characterized in that: The following steps are involved: preparing a mixed ceramic powder, wherein the mixed ceramic powder comprises silicon nitride powder; Mixing and grinding the mixed ceramic powder and the first solvent to prepare silicon nitride slurry; heating the silicon nitride slurry at a first temperature to obtain a silicon nitride mixed powder block; crushing and sieving the silicon nitride mixed powder block to obtain a silicon nitride mixed powder; preparing first molded particles and second molded particles by using silicon nitride mixed powder; The first molded particles include paraffin wax and a first thermoplastic resin; the second molded particles include a second thermoplastic resin; Using the first molded particles and the second molded particles to prepare a layered silicon nitride ceramic primary body through an FDM printer; subjecting the layered silicon nitride ceramic body to a debinding treatment in a second solvent to obtain a secondary layered silicon nitride ceramic body; heating the secondary layered silicon nitride ceramic body to perform a secondary binder removal treatment to obtain a layered silicon nitride ceramic body; The layered silicon nitride ceramic body is sintered to obtain the layered silicon nitride ceramic antenna cover.

2. The method for integrally forming a layered silicon nitride ceramic radome according to claim 1, characterized in that: The preparation process of the mixed ceramic powder comprises the following steps: mixing α-silicon nitride powder and a sintering aid in a mass ratio of (88-92): (7-13) to obtain the mixed ceramic powder; The sintering aid comprises one or more of aluminum oxide, yttrium oxide, and lanthanum oxide. Preferably, the sintering aid comprises aluminum oxide, yttrium oxide, and lanthanum oxide in a mass ratio of (4-6): (2-5): (1-2).

3. The method for integrally forming a layered silicon nitride ceramic radome according to claim 1, wherein: The specific process of preparing silicon nitride slurry includes the following steps: The mixed ceramic powder and the first solvent are mixed and ball-milled in a mass ratio of (8-12): (18-22) for 70-74 hours to obtain a silicon nitride slurry; The first solvent is ethanol or methanol.

4. The method for integrally forming a layered silicon nitride ceramic radome according to claim 1, wherein: During the preparation of the silicon nitride mixed powder block, the first temperature is 60° C. to 80° C., and the heating time is 20-26 hours.

5. The method for integrally forming a layered silicon nitride ceramic radome according to claim 1, characterized in that: The silicon nitride mixed powder comprises a first silicon nitride mixed powder and a second silicon nitride mixed powder; The process of preparing the first shaped particles comprises the following steps: The first silicon nitride mixed powder, paraffin wax, and the first thermoplastic resin are heated and kneaded at 150° C. to 200° C. in a mass ratio of (78-83): (9-13): (6-9) for 1 to 2 hours; and then extruded and granulated at 130° C. to 180° C. and an extrusion pressure of 20 MPa to 35 MPa to obtain first molded particles with a particle size of 2 to 2.2 mm. The process of preparing the second shaped particles comprises the following steps: The second silicon nitride mixed powder, paraffin wax, and the second thermoplastic resin are heated and kneaded at 150° C.-180° C. in a mass ratio of (85-92): (3-7): (5-8) for 1-2 hours; then, they are extruded and granulated at 130° C.-160° C. and an extrusion pressure of 20 MPa-35 MPa to obtain second molded particles with a particle size of 1-1.6 mm.

6. The method for integrally forming a layered silicon nitride ceramic radome according to claim 5, characterized in that: The particle size of the first silicon nitride mixed powder is 30-60 mesh; the particle size of the second silicon nitride mixed powder is 50-60 mesh; and / or The first thermoplastic resin includes thermoplastic resin A and thermoplastic resin B; the first thermoplastic resin includes thermoplastic resin A; The volatilization temperature of the thermoplastic resin A is 200-300°C; the volatilization temperature of the thermoplastic resin B is 300-500°C; Thermoplastic resin A includes one or more of organic glass, acrylonitrile-butadiene-styrene copolymer, and ethylene-vinyl acetate copolymer; The thermoplastic resin B includes one or more of high-density polyethylene, polypropylene, and polystyrene.

7. The method for integrally forming a layered silicon nitride ceramic radome according to claim 1, characterized in that: The process of preparing a layered silicon nitride ceramic primary body comprises the following steps: The FDM printer includes a first material outlet and a second material outlet; the first molded particles are heated and flow out of the first material outlet, and the second molded particles are heated and flow out of the second material outlet; Printing process: Multi-layer printing according to 1-n layers, each layer is set in the horizontal direction, and the 1-n layers are connected in sequence in the vertical direction; Each layer includes a plurality of first material strips and a plurality of second material strips; the first material strips and the second material strips are arranged horizontally at intervals; the first material strips and the second material strips are arranged in parallel; The first material strip is arranged at an angle to the horizontal direction; The first material passes through the first material outlet and prints the first material strip from top to bottom. Then the second material passes through the second material outlet and prints the second material strip from top to bottom. This is one cycle. Then, this cycle is repeated to form the first layer. Then, the second layer is printed on top of the first layer, and then the 3-n layers are printed in sequence; thus, the layered silicon nitride ceramic primary body is obtained.

8. The method for integrally forming a layered silicon nitride ceramic radome according to claim 7, wherein: The angle between the first material strip of the nth layer and the horizontal direction is αn; the αn ​​of two adjacent layers is different.

9. The method for integrally forming a layered silicon nitride ceramic radome according to claim 8, characterized in that: When n is an even number, the angle of αn of the nth layer is <90°; When n is an odd number, the angle of αn of the nth layer is > 90°; or When n is an even number, the angle of αn of the nth layer is > 90°; When n is an odd number, the angle αn of the nth layer is less than 90°.

10. A layered silicon nitride ceramic radome, characterized in that: It is prepared by the integrated molding method of the layered silicon nitride ceramic antenna cover according to any one of claims 1 to 9; The layered silicon nitride ceramic radome comprises 1-n layers of silicon nitride ceramic; each layer of silicon nitride ceramic is arranged in a horizontal direction, and the 1-n layers of silicon nitride ceramic are sequentially connected in a vertical direction; Each layer of silicon nitride ceramic includes a plurality of first ceramic strips and a plurality of second ceramic strips; the first ceramic strips and the second ceramic strips are arranged horizontally and spaced apart from each other; the first ceramic strips and the second ceramic strips are arranged in parallel; The first material strip is arranged at an angle to the horizontal direction; The porosity of the first ceramic strip is 80-90%, and the porosity of the second ceramic strip is 10-20%; The wave transmission performance of the layered silicon nitride ceramic radome is ≥75%; The dielectric constant of the layered silicon nitride ceramic antenna cover is in the range of 2-4.