A method for preparing a laminated wide-band wave-transmitting silicon nitride ceramic antenna cover

Abstract

The present invention relates to a method for preparing a laminated structure broadband wave-transmitting silicon nitride ceramic radome, comprising the following steps: cutting the corresponding radome layer tape-cast blank strips according to n radome topological layer data models to obtain n radome layer blank sheets corresponding to the radome layer tape-cast blank strips; sequentially coating the n radome layer blank sheets on the surface of a radome film core, the n radome layer blank sheets form n radome blank layers, and n connected radome blank layers are obtained on the surface of the radome film core; sleeves the radome mold shell on the surface of the film core coating the n radome blank layers, and the n radome blank layers are located between the radome mold shell and the radome film core; performing a binder removal heat treatment on the laminated structure ceramic radome blank body, and sintering the laminated structure ceramic radome blank under a nitrogen atmosphere to obtain a laminated structure broadband wave-transmitting silicon nitride ceramic radome; and the ceramic radome having both high temperature resistance and broadband wave-transmitting performance is prepared, and the overall high temperature resistance performance is good.

Description

Technical Field

[0001] The present invention relates to the technical field of wave-transmitting silicon nitride ceramic radomes, and in particular to the technical field of a method for preparing a wide-band wave-transmitting silicon nitride ceramic radome with a laminated structure. Background Art

[0002] The radome is a key component of the radar guidance system. It protects the internal seeker from external high-speed flight aerodynamic thermal ablation and effectively transmits electromagnetic waves. It has the functions of heat protection, load bearing and wave transmission. With the continuous improvement of combat requirements such as equipment flight speed, precision guidance, attack and defense confrontation, the development of ceramic radomes with both high temperature resistance and broadband wave transmission performance has become one of the research hotspots at home and abroad.

[0003] The traditional method now is to bond high temperature resistant materials with different electromagnetic parameters together and then process them into a ceramic antenna cover with high temperature resistance and broadband wave transmission performance. However, the high temperature resistance of the joints of different layers of the ceramic antenna cover processed in this way is low, and the wave transmission performance of each part of the antenna cover body after the material is processed is uncontrollable;

[0004] Therefore, how to prepare a ceramic antenna cover that has both high temperature resistance and broadband wave transmission performance, with the antenna cover body sintered in one piece, good overall high temperature resistance, and relatively uniform wave transmission performance in each part, has become a difficult problem that needs to be urgently solved in this field. Summary of the invention

[0005] In order to solve the above technical problems, the purpose of the present invention is to provide a method for preparing a laminated structure broadband wave-transmitting silicon nitride ceramic antenna cover, so as to realize the preparation of a ceramic antenna cover with both high temperature resistance and broadband wave-transmitting performance, and the antenna cover body is sintered into an integral body, with good overall high temperature resistance and relatively uniform wave-transmitting performance in each part.

[0006] The present invention provides a method for preparing a laminated wide-band wave-transmitting silicon nitride ceramic radome, comprising the following steps:

[0007] The silicon nitride ceramic radome data model is input into the system, and the silicon nitride ceramic radome data model is decomposed into n radome layer data models along the radial direction by the system, where n≥3;

[0008] Decomposing n radome layer data models into n radome topology plane layer data models;

[0009] preparing n radome layer slurries corresponding to n radome topology plane layer data models;

[0010] n radome layer slurries are prepared into corresponding n radome layer tape casting strips;

[0011] According to the n radome topology layer data models, the corresponding radome layer tape-casting blank strips are cut to obtain n radome layer blank sheets corresponding to the radome layer tape-casting blank strips;

[0012] The n antenna cover layer blanks are sequentially coated on the surface of the antenna cover film core, and the n antenna cover layer blanks form n antenna cover blank layers, and n connected antenna cover blank layers are obtained on the surface of the antenna cover film core; the projections of the connection lines of any two antenna cover blank layers on the plane passing through the axis of the antenna cover mold core do not overlap;

[0013] The radome mold shell is placed on the surface of the film core covering the n radome blank layers, and the n radome blank layers are located between the radome mold shell and the radome film core;

[0014] The n antenna cover blank layers are pressed and consolidated at a temperature of 50°C to 70°C and a pressure of 2-200MPa, and after the pressure is released, a laminated structure ceramic antenna cover blank is obtained;

[0015] The laminated ceramic radome blank is subjected to a binder removal heat treatment to obtain a laminated ceramic radome blank;

[0016] The laminated structure ceramic radome blank is sintered in a nitrogen atmosphere to obtain a laminated structure broadband wave-transmitting silicon nitride ceramic radome; the laminated structure broadband wave-transmitting silicon nitride ceramic radome is composed of n radome ceramic layers connected together.

[0017] Compared with the prior art, the present invention has the following beneficial effects: by radially decomposing the silicon nitride ceramic radome data model into n radome layer data models, the laminated structure wide-band wave-transparent silicon nitride ceramic radome can be uniformly decomposed into n radome layer data models in the radial direction; then the n radome layer data models are decomposed into n radome topology plane layer data models, so that the radome layer data models can be flattened and unfolded to form a plane, so that the n radome layer blanks constituting the laminated structure ceramic radome blank can be processed separately;

[0018] By preparing n antenna cover layer tape casting green sheets, the corresponding antenna cover layer green sheets can be formed, and at the same time, the antenna cover layer green sheets are bonded together to obtain a laminated structure ceramic antenna cover green body;

[0019] By preparing n corresponding radome layer casting strips from n radome layer slurries, different compositions of the prepared radome layer green sheets can be achieved, thereby achieving different porosities and dielectric constants of the radome ceramic layers corresponding to the radome layer green sheets;

[0020] The n antenna cover blank layers are pressed and consolidated at a temperature of 50° C. to 70° C. and a pressure of 2-200 MPa, and then the pressure is released to obtain a laminated structure ceramic antenna cover blank; thereby, the laminated structure ceramic antenna cover blank is subjected to binder removal and sintering, thereby realizing an integrated sintering molding of the laminated structure ceramic antenna cover blank, thereby achieving good overall high temperature resistance and relatively uniform wave transmission performance of each part;

[0021] By making the projections of the connecting lines of any two antenna cover blank layers on the plane passing through the axis of the antenna cover mold core not overlap, it is possible to obtain a laminated ceramic antenna cover blank while avoiding the influence of the connecting seams of the antenna cover blank layers on the strength of the laminated wide-band transparent silicon nitride ceramic antenna cover.

[0022] Furthermore, decomposing the n radome layer data models into n radome topology plane layer data models includes the following steps:

[0023] Designing corresponding n cutting lines for n radome layer data models, splitting each radome layer data model along the corresponding cutting lines, and obtaining a planar radome topology plane layer data model;

[0024] The projections of any two cutting lines on the plane passing through the axis of the silicon nitride ceramic radome data model do not overlap.

[0025] The beneficial effect of adopting the previous step is that the projections of any two cutting lines on the plane passing through the axis of the silicon nitride ceramic antenna cover data model do not overlap, so that the projections of the connecting lines of any two antenna cover blank layers on the plane passing through the axis of the antenna cover mold core do not overlap, thereby achieving a laminated structure ceramic antenna cover blank body while avoiding the connection seams of the antenna cover blank layers from affecting the strength of the laminated structure broadband transparent silicon nitride ceramic antenna cover.

[0026] Furthermore, the cutting line is not a straight line, and preferably the cutting line is a zigzag fold line or the cutting line is composed of a plurality of adjacent inverted trapezoids lacking a lower base and a trapezoid lacking an upper base.

[0027] The beneficial effect of adopting the previous step is that the cutting line is not a straight line, which is conducive to achieving high strength of the connection seam between any two antenna cover blank layers; the cutting line is composed of a plurality of adjacent inverted trapezoids lacking a lower bottom edge and a trapezoid lacking an upper bottom edge, which is further conducive to achieving high strength of the connection seam between any two antenna cover blank layers.

[0028] Furthermore, the n antenna cover layer slurries all include silicon nitride powder, rare earth oxide sintering aid, organic additives, and organic solvents; the mass ratio of the silicon nitride powder to the rare earth oxide sintering aid is (90-97): (3-10);

[0029] At least one of the n radome layer slurries comprises silicon nitride powder and silicon powder.

[0030] The beneficial effect of adopting the previous step is that at least one of the n antenna cover layer slurries includes silicon nitride powder and silicon powder, so that the solid content of each antenna cover layer in the laminated ceramic antenna cover blank is not very high, which is conducive to smooth debinding of each antenna cover layer and no cracking; at the same time, the surface antenna cover layer slurry includes silicon powder, so that the strength of silicon nitride generated after the nitriding reaction of silicon powder during the sintering process is increased and the density of the surface antenna cover layer is increased. While improving the strength, the dielectric constant of the surface layer is further changed, which is conducive to achieving different dielectric constants between the surface antenna cover layer and the adjacent antenna cover layer.

[0031] Furthermore, at least one of the n radome slurries comprises silicon nitride powder, rare earth oxide sintering aid, silicon powder, organic additive, and organic solvent in a mass ratio of (90-97): (3-10): (10-30): (20-30): (50-75);

[0032] At least one of the n radome slurries comprises silicon nitride powder, rare earth oxide sintering aid, pore former powder, organic additive, and organic solvent in a mass ratio of (90-97): (3-10): (10-30): (20-30), (50-75);

[0033] Preferably, the radome blank layer prepared by the radome layer slurry containing silicon powder is located on the outer surface layer of the laminated structure ceramic radome blank body.

[0034] The beneficial effect of adopting the previous step is that at least one of the n antenna cover layer slurries includes silicon nitride powder, rare earth oxide sintering aid, silicon powder, organic additive, and organic solvent in a mass ratio of (90-97): (3-10): (10-30): (20-30): (50-75), so that at least one antenna cover layer slurry contains silicon powder and has a low solid content. The volatile matter of the antenna cover blank layer corresponding to the antenna cover layer slurry containing silicon powder is easy to volatilize during the debinding process, and will not cause problems such as fracture or damage of the laminated structure ceramic antenna cover blank. At the same time, the silicon powder of the antenna cover blank layer containing silicon powder undergoes a nitridation reaction during the sintering process after the debinding is completed, so that the porosity of the corresponding antenna cover ceramic layer is reduced, the strength is increased, the density is increased, and the dielectric constant is high.

[0035] At least one of the n radome layer slurries comprises silicon nitride powder, rare earth oxide sintering aid, pore former powder, organic additive, and organic solvent in a mass ratio of (90-97): (3-10): (10-30): (20-30), (50-75), so that at least one radome layer slurry has a high pore former content or a high solid content, thereby achieving high porosity and low dielectric constant of at least one radome ceramic layer after sintering;

[0036] Preferably, the antenna cover blank layer prepared by the antenna cover layer slurry containing silicon powder is located on the outer surface layer of the laminated structure ceramic antenna cover blank. The antenna cover blank layer prepared by the antenna cover layer slurry containing silicon powder can facilitate smooth debinding even with a low solid content, avoiding problems such as breakage or damage of the laminated structure ceramic antenna cover blank. At the same time, the silicon powder undergoes nitridation reaction during sintering after debinding, thereby reducing the porosity of the outer surface layer of the laminated structure ceramic antenna cover blank and increasing the density, thereby achieving a high degree of densification on the outer surface of the laminated structure wide-band transparent silicon nitride ceramic antenna cover, high thermal shock resistance, high strength, and high dielectric constant, while not affecting the debinding inside the laminated structure ceramic antenna cover blank, thereby improving the quality of the laminated structure wide-band transparent silicon nitride ceramic antenna cover.

[0037] Furthermore, the median particle size of the silicon nitride powder is 0.5 μm-2 μm, and the α-Si 3 N 4 The content is not less than 91%, and the total content of metal impurity elements is not higher than 0.15%;

[0038] The rare earth oxide sintering aid includes yttrium oxide and / or lanthanum oxide, and the median particle size is 0.2 μm-1.5 μm;

[0039] The pore-forming agent includes one of starch, polypropylene microspheres, and polymethyl methacrylate microspheres, and the median particle size of the pore-forming agent is 1 μm-5 μm;

[0040] The purity of the silicon powder is not less than 99%, and the median particle size is 0.5 μm-3 μm;

[0041] The organic additives include polyvinyl butyral and dibutyl phthalate;

[0042] The organic solvent is ethanol or methanol.

[0043] The beneficial effect of the above step is that the median particle size of the silicon nitride powder is 0.5 μm-2 μm, the median particle size of the rare earth oxide sintering aid is 0.2 μm-1.5 μm, the median particle size of the pore former is 1 μm-5 μm, and the median particle size of the silicon powder is 0.5 μm-3 μm, thereby avoiding the particle size of the raw material being too large, which is conducive to realizing the radome layer mud casting molding to obtain the radome layer casting blank strip; at the same time, avoiding the particle size of the raw material being too large, which is conducive to realizing the bonding between the radome layer blanks to obtain a laminated structure ceramic radome blank;

[0044] The organic additives including polyvinyl butyral and dibutyl phthalate are further conducive to the radome layer slurry tape casting to obtain the radome layer tape casting blank, and are conducive to improving the strength of the radome layer tape casting blank, thereby facilitating the cutting of the radome layer tape casting blank and facilitating the preparation of a laminated structure ceramic radome blank body by the radome blank layer.

[0045] Furthermore, the debinding heat treatment process of the laminated ceramic antenna cover blank is as follows: heating to 90-120°C at a heating rate of 9-10°C / min, heating from 90-120°C to 200-220°C at a heating rate of 4-5°C / min, heating from 200-220°C to 430-450°C at a heating rate ≤0.5°C / min; heating from 430-450°C to 550°C-650°C at a heating rate of 2-3°C / min; heating under negative pressure or circulating air / nitrogen atmosphere; preferably, heating under negative pressure, the negative pressure range is -0.096MP to -0.07MPa.

[0046] The beneficial effect of adopting the previous step is that by heating to 90-120°C at a heating rate of 9-10°C / min, it is conducive to the rapid volatilization of small molecular volatiles in the surface layer of the laminated structure ceramic antenna cover blank to form channels, and at the same time, a small amount of small molecular volatiles in the inner layer of the laminated structure ceramic antenna cover blank volatilizes, thereby avoiding the problems of cracking, deformation or blistering on the surface of the laminated structure ceramic antenna cover blank; by heating from 90-120°C to 200-220°C at a heating rate of 4-5°C / min, it is conducive to the slow volatilization of small molecular volatiles in the inner layer of the laminated structure ceramic antenna cover blank through the channels formed on the surface; by heating from 200-220°C to 430-450°C at a heating rate of ≤0.5°C / min, the slow decomposition of large molecular volatiles in the laminated structure ceramic antenna cover blank is achieved, and the slow volatilization is based on the formation of channels by small molecular volatilization;

[0047] By raising the temperature from 430-450℃ to 550℃-650℃ at a heating rate of 2-3℃ / min, since the large molecular volatiles in the surface layer of the laminated ceramic antenna cover blank are basically evaporated and the volatilization channels with larger apertures have been formed, the volatilization rate of the laminated ceramic antenna cover blank can be increased. Therefore, a slight increase in the heating rate will not affect the laminated ceramic antenna cover blank, and at the same time avoid the problem of high fluidity when some raw materials in the laminated ceramic antenna cover blank are softened.

[0048] Furthermore, the sintering process of the laminated structure ceramic antenna cover blank in a nitrogen atmosphere includes the following steps: heating from 1150-1200°C to 1380-1420°C at a heating rate of 0.5-1.5°C / min, and keeping at 1380-1420°C for 3-5h; heating from 1380-1420°C to 1600-1700°C at a heating rate of 0.75-1°C / min, and keeping at 1600-1700°C for 1-2h; sintering in a slightly positive pressure nitrogen atmosphere with a nitrogen flow rate of 200-2000ml / min; and a nitrogen pressure of 0.3-2.0MPa.

[0049] The beneficial effect of adopting the previous step is that while the laminated structure ceramic antenna cover blank is sintered to obtain the laminated structure wide-band transparent silicon nitride ceramic antenna cover, the silicon powder in the laminated structure ceramic antenna cover blank is nitrided to generate silicon nitride, thereby reducing the porosity of the antenna cover blank layer containing silicon powder, increasing the degree of densification, and increasing the dielectric constant.

[0050] Furthermore, at least two radome ceramic layers have different dielectric constants.

[0051] The beneficial effect of adopting the previous step is that the laminated structure broadband wave-transmitting silicon nitride ceramic antenna cover has both high temperature resistance and broadband wave-transmitting performance.

[0052] Further, when n=3, the three antenna cover layer data models are a first antenna cover layer data model, a second antenna cover layer data model, and a third antenna cover layer data model sequentially connected from the outer wall to the inner wall of the silicon nitride ceramic antenna cover data model;

[0053] The three radome topology plane layer data models are the first radome topology plane layer data model, the second radome topology plane layer data model, and the third radome topology plane layer data model respectively decomposed into the first radome topology plane layer data model, the second radome topology plane layer data model, and the third radome topology plane layer data model;

[0054] The three radome layer muds are the first radome layer mud, the second radome layer mud, and the third radome layer mud corresponding to the first radome topology plane layer data model, the second radome layer mud, and the third radome layer mud respectively;

[0055] The first antenna cover layer slurry comprises silicon nitride powder, rare earth oxide sintering aid, silicon powder, organic additives, and organic solvent in a mass ratio of (90-97): (3-10): (10-30): (20-30): (50-75);

[0056] The second antenna cover layer slurry comprises silicon nitride powder, rare earth oxide sintering aid, pore former powder, organic additive, and organic solvent in a mass ratio of (90-97): (3-10): (10-30): (20-30): (50-75);

[0057] The third radome layer slurry comprises silicon nitride powder, rare earth oxide sintering aid, silicon powder, organic additives, and organic solvent in a mass ratio of (90-97): (3-10): (0-30): (10-30): (40-75);

[0058] The laminated structure broadband wave-transmitting silicon nitride ceramic radome is composed of a first radome ceramic layer, a second radome ceramic layer, and a third radome ceramic layer connected in sequence from the outer wall to the inner wall;

[0059] The first radome ceramic layer is prepared by first radome layer slurry, the second radome ceramic layer is prepared by second radome layer slurry, and the third radome ceramic layer is prepared by third radome layer slurry;

[0060] The density of the first antenna cover ceramic layer and the third antenna cover ceramic layer is greater than that of the second antenna cover ceramic layer, and the porosity of the first antenna cover ceramic layer and the third antenna cover ceramic layer is less than that of the second antenna cover ceramic layer; the dielectric constant of the first antenna cover ceramic layer is greater than that of the second antenna cover ceramic layer;

[0061] Preferably, the third radome layer slurry comprises silicon nitride powder, rare earth oxide sintering aid, silicon powder, organic additives, and organic solvent in a mass ratio of (90-97): (5-15): (10-30): (40-50);

[0062] Preferably, the third antenna cover layer slurry comprises silicon nitride powder, rare earth oxide sintering aid, silicon powder, organic additives, and organic solvent in a mass ratio of (90-97): (3-10): (5-15): (10-30): (50-75).

[0063] The beneficial effect of adopting the previous step is that the prepared laminated structure broadband wave-transmitting silicon nitride ceramic radome includes a first radome ceramic layer, a second radome ceramic layer, and a third radome ceramic layer. The first radome ceramic layer as the outer surface layer of the laminated structure broadband wave-transmitting silicon nitride ceramic radome and the third radome ceramic layer as the inner surface layer of the laminated structure broadband wave-transmitting silicon nitride ceramic radome have a high degree of densification, which is conducive to achieving high strength and good heat shock resistance of the laminated structure broadband wave-transmitting silicon nitride ceramic radome, and achieving that the laminated structure broadband wave-transmitting silicon nitride ceramic radome has at least two layers with different dielectric properties, while avoiding the problem of moisture absorption caused by high porosity of the outer and inner surface layers of the broadband wave-transmitting silicon nitride ceramic radome, and each layer is evenly distributed, so that the laminated structure broadband wave-transmitting silicon nitride ceramic radome has both high temperature resistance and broadband wave-transmitting performance;

[0064] The solid content of the first antenna cover layer slurry and the third antenna cover layer slurry is not lower than or not significantly lower than that of the second antenna cover layer slurry, which is beneficial to the debinding of the second antenna cover layer located in the middle of the laminated structure ceramic antenna cover blank when the laminated structure ceramic antenna cover blank is debinded, and will not cause damage to the laminated structure ceramic antenna cover blank; at the same time, the first antenna cover layer slurry or the first antenna cover layer slurry and the third antenna cover layer slurry contain silicon powder, so that the porosity of the first antenna cover layer or the first antenna cover layer and the third antenna cover layer is reduced and densified during the sintering process;

[0065] By including a pore-forming agent in the second antenna cover layer slurry, the porosity of the second antenna cover blank layer can be improved, thereby achieving a different dielectric constant between the second antenna cover ceramic layer and the first antenna cover ceramic layer and the third antenna cover ceramic layer;

[0066] Thereby, the laminated structure broadband wave-transmitting silicon nitride ceramic antenna cover has both high temperature resistance and broadband wave-transmitting performance, and the antenna cover body is sintered in one piece, the overall high temperature resistance is good, and the wave-transmitting performance of each part is relatively uniform. DETAILED DESCRIPTION

[0067] In order to better understand the technical solution of the present invention, the present invention is further described below in conjunction with specific embodiments.

[0068] Embodiment 1

[0069] This embodiment provides a method for preparing a laminated wide-band wave-transmitting silicon nitride ceramic radome, comprising the following steps:

[0070] The silicon nitride ceramic radome data model is input into the system, and the silicon nitride ceramic radome data model is decomposed into three radome layer data models along the radial direction by the system;

[0071] Decompose the three radome layer data models into three radome topology plane layer data models;

[0072] Prepare three radome layer muds corresponding to three radome topology plane layer data models;

[0073] The three radome layer muds are the first radome layer mud, the second radome layer mud, and the third radome layer mud corresponding to the first radome topology plane layer data model, the second radome layer mud, and the third radome layer mud respectively;

[0074] The first radome layer slurry comprises silicon nitride powder, rare earth oxide sintering aid, silicon powder, organic additives, and organic solvent in a mass ratio of 93:6:20:25:62;

[0075] The second radome layer slurry comprises silicon nitride powder, rare earth oxide sintering aid, pore former powder, organic additive, and organic solvent in a mass ratio of 93:6:20:25:62;

[0076] The third radome layer slurry comprises silicon nitride powder, rare earth oxide sintering aid, silicon powder, organic additives, and organic solvent in a mass ratio of 93:6:20:25:62;

[0077] The median particle size of the silicon nitride powder is 1.5 μm. 3 N 4 The content is not less than 91%, and the total content of metal impurity elements is not higher than 0.15%;

[0078] The rare earth oxide sintering aid includes lanthanum oxide, and the median particle size is 1 μm;

[0079] The pore-forming agent includes polypropylene microspheres, and the median particle size of the pore-forming agent is 3.5 μm;

[0080] The purity of the silicon powder is not less than 99%, and the median particle size is 2 μm;

[0081] The organic additive includes dibutyl phthalate;

[0082] The organic solvent is ethanol.

[0083] The first antenna cover layer slurry, the second antenna cover layer slurry, and the third antenna cover layer slurry are respectively prepared into corresponding first antenna cover layer tape casting blank tape, second antenna cover layer tape casting blank tape, and third antenna cover layer tape casting blank tape;

[0084] According to the three radome topology layer data models, the corresponding radome layer tape-casting blank strips are cut to obtain three radome layer blank sheets corresponding to the radome layer tape-casting blank strips;

[0085] The first antenna cover layer tape-casting blank strip, the second antenna cover layer tape-casting blank strip, and the third antenna cover layer tape-casting blank strip are cut to obtain the first antenna cover layer blank sheet, the second antenna cover layer blank sheet, and the third antenna cover layer blank sheet;

[0086] Designing three corresponding cutting lines for the three radome layer data models, dividing each radome layer data model along the corresponding cutting lines, and obtaining a planar radome topology plane layer data model; the cutting lines are straight lines;

[0087] The projections of any two cutting lines on the plane passing through the axis of the silicon nitride ceramic radome data model do not overlap;

[0088] The third antenna cover layer blank sheet, the second antenna cover layer blank sheet, and the first antenna cover layer blank sheet are sequentially coated on the surface of the antenna cover film core, that is, the third antenna cover layer blank sheet is first coated on the surface of the antenna cover film core, and then the second antenna cover layer blank sheet is coated, and finally the first antenna cover layer blank sheet is coated, and the third antenna cover layer blank sheet, the second antenna cover layer blank sheet, and the first antenna cover layer blank sheet respectively form the third antenna cover layer, the second antenna cover layer, and the first antenna cover layer, and the third antenna cover layer, the second antenna cover layer, and the first antenna cover layer are sequentially formed on the surface of the antenna cover film core from near to far; the projections of the connecting lines of any two antenna cover layers on the plane passing through the axis of the antenna cover mold core do not overlap;

[0089] The radome mold shell is placed on the surface of the film core covering the three radome blank layers, and the three radome blank layers are located between the radome mold shell and the radome film core;

[0090] The three antenna cover blank layers are pressed and consolidated at a temperature of 60°C and a pressure of 100 MPa, and after the pressure is released, a laminated structure ceramic antenna cover blank is obtained;

[0091] The laminated ceramic antenna cover blank is subjected to a debinding heat treatment to obtain a laminated ceramic antenna cover blank; the debinding heat treatment process of the laminated ceramic antenna cover blank is as follows: heating to 105°C at a heating rate of 9.5°C / min, heating from 105°C to 210°C at a heating rate of 4.5°C / min, heating from 210°C to 440°C at a heating rate of 0.4°C / min; heating from 440°C to 600°C at a heating rate of 2.5°C / min; heating in a circulating air atmosphere.

[0092] Sintering the laminated structure ceramic radome blank in a nitrogen atmosphere to obtain a laminated structure broadband wave-transmitting silicon nitride ceramic radome;

[0093] The sintering process of the laminated structure ceramic antenna cover blank in a nitrogen atmosphere includes the following steps: heating from 1180°C to 1400°C, with a heating rate of 1°C / min, and keeping at 1400°C for 4 hours; heating from 1400°C to 1650°C, with a heating rate of 0.86°C / min, and keeping at 1650°C for 1.5 hours; sintering in a slightly positive pressure nitrogen atmosphere, with a nitrogen flow rate of 1100ml / min; and a nitrogen pressure of 1.2MPa;

[0094] The laminated structure broadband wave-transmitting silicon nitride ceramic radome is composed of three radome ceramic layers connected together; wherein the dielectric constants of the two radome ceramic layers are different;

[0095] The laminated structure broadband wave-transmitting silicon nitride ceramic radome is composed of a first radome ceramic layer, a second radome ceramic layer, and a third radome ceramic layer connected in sequence from the outer wall to the inner wall;

[0096] The first radome ceramic layer is prepared by first radome layer slurry, the second radome ceramic layer is prepared by second radome layer slurry; the third radome ceramic layer is prepared by third radome layer slurry;

[0097] The density of the first antenna cover ceramic layer and the third antenna cover ceramic layer is greater than that of the second antenna cover ceramic layer, and the porosity of the first antenna cover ceramic layer and the third antenna cover ceramic layer is less than that of the second antenna cover ceramic layer; the dielectric constant of the first antenna cover ceramic layer is greater than that of the second antenna cover ceramic layer.

[0098] Embodiment 2

[0099] The features of this embodiment that are the same as those of the first embodiment are not described in detail. The features of this embodiment that are different from those of the first embodiment are as follows: a method for preparing a laminated structure broadband wave-transmitting silicon nitride ceramic antenna cover provided in this embodiment comprises the following steps, wherein the cutting line is a sawtooth fold line;

[0100] The first radome layer slurry includes silicon nitride powder, rare earth oxide sintering aid, silicon powder, organic additives, and organic solvent in a mass ratio of 96:9:28:28:73;

[0101] The second radome slurry includes silicon nitride powder, rare earth oxide sintering aid, pore former powder, organic additive, and organic solvent in a mass ratio of 96:9:28:28:73;

[0102] The third radome layer slurry comprises silicon nitride powder, rare earth oxide sintering aid, silicon powder, organic additives, and organic solvent in a mass ratio of 96:9:14:28:73;

[0103] The median particle size of the silicon nitride powder is 1.8 μm;

[0104] The rare earth oxide sintering aid includes yttrium oxide, and the median particle size is 1.3 μm;

[0105] The pore-forming agent includes starch, and the median particle size of the pore-forming agent is 4.5 μm;

[0106] The purity of the silicon powder is not less than 99%, and the median particle size is 2.6 μm;

[0107] The organic additive includes polyvinyl butyral;

[0108] The organic solvent is methanol.

[0109] The three antenna cover blank layers are pressed and consolidated at a temperature of 65°C and a pressure of 180MPa, and after the pressure is released, a laminated structure ceramic antenna cover blank is obtained;

[0110] The debinding heat treatment process of the laminated structure ceramic antenna cover blank is as follows: heating to 118°C at a heating rate of 9.8°C / min, heating from 118°C to 218°C at a heating rate of 4.8°C / min, heating from 218°C to 445°C at a heating rate of 0.45°C / min; heating from 445°C to 630°C at a heating rate of 2.8°C / min; heating in a negative pressure atmosphere;

[0111] The sintering process of the laminated structure ceramic antenna cover blank in a nitrogen atmosphere includes the following steps: heating from 1180°C to 1410°C, with a heating rate of 1.3°C / min, and keeping at 1410°C for 4.8 hours; heating from 1410°C to 1680°C, with a heating rate of 0.9°C / min, and keeping at 1680°C for 1.8 hours; sintering in a slightly positive pressure nitrogen atmosphere, with a nitrogen flow rate of 1800ml / min; and a nitrogen pressure of 1.8Pa;

[0112] The laminated structure broadband wave-transmitting silicon nitride ceramic radome is composed of three radome ceramic layers connected together; the three radome ceramic layers have different dielectric constants;

[0113] The dielectric constant of the first radome ceramic layer is greater than the dielectric constant of the third radome ceramic layer, and the dielectric constant of the third radome ceramic layer is greater than the dielectric constant of the second radome ceramic layer.

[0114] Embodiment 3

[0115] The features of this embodiment that are the same as those of the first embodiment are not described in detail. The features of this embodiment that are different from those of the first embodiment are as follows: a method for preparing a wide-band wave-transmitting silicon nitride ceramic antenna cover with a laminated structure provided in this embodiment comprises the following steps, wherein the cutting line is composed of a plurality of adjacent inverted trapezoids lacking a lower bottom edge and a trapezoid lacking an upper bottom edge;

[0116] The first radome slurry includes silicon nitride powder, rare earth oxide sintering aid, silicon powder, organic additives, and organic solvent in a mass ratio of 91:4:22:22:53;

[0117] The second radome slurry includes silicon nitride powder, rare earth oxide sintering aid, pore former powder, organic additive, and organic solvent in a mass ratio of 91:4:15:22:53;

[0118] The third radome layer slurry comprises silicon nitride powder, rare earth oxide sintering aid, silicon powder, organic additives, and organic solvent in a mass ratio of 95:6:22:43;

[0119] The median particle size of the silicon nitride powder is 0.6 μm;

[0120] The rare earth oxide sintering aid includes lanthanum oxide, and the median particle size is 0.6 μm;

[0121] The pore-forming agent includes one of polymethyl methacrylate microspheres, and the median particle size of the pore-forming agent is 1.5 μm;

[0122] The median particle size of the silicon powder is 0.8 μm;

[0123] The organic additive includes polyvinyl butyral and dibutyl phthalate; the organic solvent is methanol;

[0124] The n antenna cover blank layers are pressed and consolidated at a temperature of 55° C. and a pressure of 50 MPa, and after the pressure is released, a laminated structure ceramic antenna cover blank is obtained;

[0125] The debinding heat treatment process of the laminated structure ceramic antenna cover blank is as follows: heating to 92°C at a heating rate of 9.2°C / min, heating from 92°C to 205°C at a heating rate of 4.1°C / min, heating from 205°C to 435°C at a heating rate of 0.48°C / min; heating from 435°C to 560°C at a heating rate of 2.2°C / min; heating in a nitrogen atmosphere;

[0126] The sintering process of the laminated structure ceramic antenna cover blank in a nitrogen atmosphere comprises the following steps: heating from 1160°C to 1390°C at a heating rate of 0.6°C / min and keeping at 1390°C for 4.8 hours; heating from 1390°C to 1620°C at a heating rate of 0.76°C / min and keeping at 1620°C for 1.8 hours; sintering in a slightly positive pressure nitrogen atmosphere with a nitrogen flow rate of 500ml / min and a nitrogen pressure of 0.5MPa;

[0127] The dielectric constant of the first radome ceramic layer is greater than the dielectric constant of the third radome ceramic layer, and the dielectric constant of the third radome ceramic layer is greater than the dielectric constant of the second radome ceramic layer.

[0128] Embodiment 4

[0129] The features of this embodiment that are the same as those of the first embodiment are not described in detail. The features of this embodiment that are different from those of the first embodiment are as follows: a method for preparing a laminated structure wide-band wave-transparent silicon nitride ceramic radome provided in this embodiment comprises the following steps: inputting the silicon nitride ceramic radome data model into a system, and decomposing the silicon nitride ceramic radome data model into five radome layer data models along the radial direction through the system, where n=5;

[0130] Decompose the five radome layer data models into five radome topology plane layer data models;

[0131] Prepare 5 radome layer muds corresponding to 5 radome topology plane layer data models;

[0132] The five radome layer muds are the first radome layer mud, the second radome layer mud, the third radome layer mud, the fourth radome layer mud, and the fifth radome layer mud corresponding to the first radome topology plane layer data model, the second radome layer mud, the third radome layer mud, the fourth radome layer mud, and the fifth radome layer mud respectively;

[0133] The first radome layer slurry includes silicon nitride powder, rare earth oxide sintering aid, silicon powder, organic additives, and organic solvent in a mass ratio of 96:9:28:28:73;

[0134] The second radome layer slurry comprises silicon nitride powder, rare earth oxide sintering aid, pore former powder, organic additive, and organic solvent in a mass ratio of 96:9:12:28:73;

[0135] The third radome layer slurry comprises silicon nitride powder, rare earth oxide sintering aid, pore former powder, organic additive, and organic solvent in a mass ratio of 96:9:20:28:73;

[0136] The fourth radome layer slurry comprises silicon nitride powder, rare earth oxide sintering aid, pore former powder, organic additive, and organic solvent in a mass ratio of 96:9:28:28:73;

[0137] The fifth radome layer slurry comprises silicon nitride powder, rare earth oxide sintering aid, silicon powder, organic additives, and organic solvent in a mass ratio of 96:9:14:28:73;

[0138] The first antenna cover layer slurry, the second antenna cover layer slurry, the third antenna cover layer slurry, the fourth antenna cover layer slurry, and the fifth antenna cover layer slurry are respectively prepared into the corresponding first antenna cover layer tape casting blank tape, the second antenna cover layer tape casting blank tape, the third antenna cover layer tape casting blank tape, the fourth antenna cover layer tape casting blank tape, and the fifth antenna cover layer tape casting blank tape;

[0139] According to the five radome topology layer data models, the corresponding radome layer tape-casting blank strips are cut to obtain five radome layer blank sheets corresponding to the radome layer tape-casting blank strips;

[0140] The first radome layer tape-casting blank tape, the second antenna cover layer tape-casting blank tape, the third radome layer tape-casting blank tape, the fourth radome layer tape-casting blank tape, and the fifth radome layer tape-casting blank tape are cut to obtain the first radome layer blank sheet, the second antenna cover layer blank sheet, the third radome layer blank sheet, the fourth radome layer blank sheet, and the fifth radome layer blank sheet;

[0141] Designing five corresponding cutting lines for the five radome layer data models, dividing each radome layer data model along the corresponding cutting lines, and obtaining a planar radome topology plane layer data model; the cutting lines are straight lines;

[0142] The projections of any two cutting lines on the plane passing through the axis of the silicon nitride ceramic radome data model do not overlap.

[0143] The fifth antenna cover layer blank sheet, the fourth antenna cover layer blank sheet, the third antenna cover layer blank sheet, the second antenna cover layer blank sheet, and the first antenna cover layer blank sheet are sequentially coated on the surface of the antenna cover film core, that is, the fifth antenna cover layer blank sheet is firstly coated on the surface of the antenna cover film core, and then the fourth antenna cover layer blank sheet, the third antenna cover layer blank sheet, the second antenna cover layer blank sheet, and the first antenna cover layer blank sheet are sequentially coated, and the fifth antenna cover layer blank sheet, the fourth antenna cover layer blank sheet, the third antenna cover layer blank sheet, the second antenna cover layer blank sheet, and the first antenna cover layer blank sheet are respectively formed into the fifth antenna cover layer, the fourth antenna cover layer, the third antenna cover layer, the second antenna cover layer, and the first antenna cover layer. The fifth antenna cover layer, the fourth antenna cover layer, the third antenna cover layer, the second antenna cover layer, and the first antenna cover layer are sequentially formed on the surface of the antenna cover film core from near to far; the projections of the connecting lines of any two antenna cover layers on the plane passing through the axis of the antenna cover mold core do not overlap;

[0144] The radome mold shell is placed on the surface of the film core covering the five radome blank layers, and the five radome blank layers are located between the radome mold shell and the radome film core;

[0145] The five antenna cover blank layers are pressed and consolidated at a temperature of 68°C and a pressure of 180MPa, and after the pressure is released, a laminated structure ceramic antenna cover blank is obtained;

[0146] The laminated ceramic antenna cover blank is subjected to a debinding heat treatment to obtain a laminated ceramic antenna cover blank; the debinding heat treatment process of the laminated ceramic antenna cover blank is as follows: heating to 118°C at a heating rate of 9.2°C / min, heating from 118°C to 218°C at a heating rate of 4.1°C / min, heating from 218°C to 448°C at a heating rate of 0.35°C / min; heating from 448°C to 640°C at a heating rate of 2.2°C / min; heating under a negative pressure atmosphere.

[0147] The sintering process of the laminated structure ceramic antenna cover blank in a nitrogen atmosphere comprises the following steps: heating from 1180°C to 1410°C at a heating rate of 0.8°C / min and keeping at 1410°C for 4.6 hours; heating from 1410°C to 1680°C at a heating rate of 0.8°C / min and keeping at 1680°C for 1.2 hours; sintering in a slightly positive pressure nitrogen atmosphere with a nitrogen flow rate of 1500ml / min and a nitrogen pressure of 1.6MPa;

[0148] The laminated structure broadband wave-transmitting silicon nitride ceramic radome is composed of five radome ceramic layers connected together; the five radome ceramic layers have different dielectric constants;

[0149] The laminated structure broadband wave-transmitting silicon nitride ceramic radome is composed of a first radome ceramic layer, a second radome ceramic layer, a third radome ceramic layer, a fourth radome ceramic layer, and a fifth radome ceramic layer connected in sequence from the outer wall to the inner wall;

[0150] The first radome ceramic layer is prepared by a first radome layer slurry, the second radome ceramic layer is prepared by a second radome layer slurry, the third radome ceramic layer is prepared by a third radome layer slurry, the fourth radome ceramic layer is prepared by a fourth radome layer slurry, and the fifth radome ceramic layer is prepared by a fifth radome layer slurry;

[0151] The density of the first antenna cover ceramic layer is greater than the density of the fifth antenna cover ceramic layer, the density of the fifth antenna cover ceramic layer is greater than the density of the second antenna cover ceramic layer, the density of the second antenna cover ceramic layer is greater than the density of the third antenna cover ceramic layer, and the density of the third antenna cover ceramic layer is greater than the density of the fourth antenna cover ceramic layer; the porosity of the first antenna cover ceramic layer is less than the porosity of the fifth antenna cover ceramic layer, the porosity of the fifth antenna cover ceramic layer is less than the porosity of the second antenna cover ceramic layer, the porosity of the second antenna cover ceramic layer is less than the porosity of the third antenna cover ceramic layer, and the porosity of the third antenna cover ceramic layer is less than the porosity of the fourth antenna cover ceramic layer; the dielectric constant of the first antenna cover ceramic layer is greater than the dielectric constant of the fifth antenna cover ceramic layer, the dielectric constant of the fifth antenna cover ceramic layer is greater than the dielectric constant of the second antenna cover ceramic layer, the dielectric constant of the second antenna cover ceramic layer is greater than the dielectric constant of the third antenna cover ceramic layer, and the dielectric constant of the third antenna cover ceramic layer is greater than the dielectric constant of the fourth antenna cover ceramic layer.

[0152] The above description is only a preferred embodiment of the present application and an explanation of the technical principles used. Those skilled in the art should understand that the scope of the invention involved in the present application is not limited to the technical solution formed by a specific combination of the above technical features, but should also cover other technical solutions formed by any combination of the above technical features or their equivalent features without departing from the inventive concept. For example, the above features are replaced with (but not limited to) technical features with similar functions disclosed in the present application.

Claims

1. A method for preparing a laminated wide-band wave-transmitting silicon nitride ceramic antenna cover, characterized in that: The following steps are involved: The silicon nitride ceramic radome data model is input into the system, and the silicon nitride ceramic radome data model is decomposed into n radome layer data models along the radial direction by the system, where n≥3; Decomposing n radome layer data models into n radome topology plane layer data models; decomposing n radome layer data models into n radome topology plane layer data models comprises the following steps: Designing corresponding n cutting lines for n radome layer data models, splitting each radome layer data model along the corresponding cutting lines, and obtaining a planar radome topology plane layer data model; The projections of any two cutting lines on the plane passing through the axis of the silicon nitride ceramic radome data model do not overlap; Prepare n radome layer slurries corresponding to n radome topology plane layer data models; the n radome layer slurries all include silicon nitride powder, rare earth oxide sintering aid, organic additive, and organic solvent; the mass ratio of the silicon nitride powder to the rare earth oxide sintering aid is (90-97): (3-10); At least one of the n radome layer slurries comprises silicon nitride powder and silicon powder; n radome layer slurries are prepared into corresponding n radome layer tape casting strips; According to the n radome topology layer data models, the corresponding radome layer tape-casting blank strips are cut to obtain n radome layer blank sheets corresponding to the radome layer tape-casting blank strips; The n antenna cover layer blanks are sequentially coated on the surface of the antenna cover film core, and the n antenna cover layer blanks form n antenna cover blank layers, and n connected antenna cover blank layers are obtained on the surface of the antenna cover film core; the projections of the connection lines of any two antenna cover blank layers on the plane passing through the axis of the antenna cover mold core do not overlap; The radome mold shell is placed on the surface of the film core covering the n radome blank layers, and the n radome blank layers are located between the radome mold shell and the radome film core; The n antenna cover blank layers are pressed and consolidated at a temperature of 50°C to 70°C and a pressure of 2-200MPa, and after the pressure is released, a laminated structure ceramic antenna cover blank is obtained; The laminated ceramic radome blank is subjected to a binder removal heat treatment to obtain a laminated ceramic radome blank; Sintering the laminated structure ceramic radome blank in a nitrogen atmosphere to obtain a laminated structure broadband wave-transmitting silicon nitride ceramic radome; the laminated structure broadband wave-transmitting silicon nitride ceramic radome is composed of n radome ceramic layers connected together; The cutting line is a sawtooth fold line or the cutting line is composed of a plurality of adjacent inverted trapezoids lacking a lower base and a trapezoid lacking an upper base.

2. The method for preparing a laminated wide-band wave-transmitting silicon nitride ceramic antenna cover according to claim 1, characterized in that: At least one of the n radome slurries comprises silicon nitride powder, rare earth oxide sintering aid, silicon powder, organic additives, and organic solvent in a mass ratio of (90-97): (3-10): (10-30): (20-30): (50-75); At least one of the n antenna cover layer slurries comprises silicon nitride powder, rare earth oxide sintering aid, pore former powder, organic additive, and organic solvent in a mass ratio of (90-97): (3-10): (10-30): (20-30), (50-75).

3. The method for preparing a laminated wide-band wave-transmitting silicon nitride ceramic radome according to claim 2, characterized in that: The median particle size of the silicon nitride powder is 0.5 μm-2 μm, the content of α-Si3N4 in the silicon nitride powder is not less than 91%, and the total content of metal impurity elements is not higher than 0.15%; The rare earth oxide sintering aid includes yttrium oxide and / or lanthanum oxide, and the median particle size is 0.2 μm-1.5 μm; The pore-forming agent includes one of starch, polypropylene microspheres, and polymethyl methacrylate microspheres, and the median particle size of the pore-forming agent is 1 μm-5 μm; The purity of the silicon powder is not less than 99%, and the median particle size is 0.5 μm-3 μm; The organic additive includes one or two of polyvinyl butyral and dibutyl phthalate; The organic solvent is ethanol or methanol.

4. The method for preparing a laminated wide-band wave-transmitting silicon nitride ceramic antenna cover according to claim 1, characterized in that: The debinding heat treatment process of the laminated structure ceramic antenna cover blank is as follows: heating to 90-120°C at a heating rate of 9-10°C / min, heating from 90-120°C to 200-220°C at a heating rate of 4-5°C / min, heating from 200-220°C to 430-450°C at a heating rate of ≤0.5°C / min; heating from 430-450°C to 550°C-650°C at a heating rate of 2-3°C / min; heating under negative pressure or circulating air / nitrogen atmosphere.

5. The method for preparing a laminated wide-band wave-transmitting silicon nitride ceramic radome according to claim 1, characterized in that: The sintering process of the laminated structure ceramic antenna cover blank in a nitrogen atmosphere comprises the following steps: heating from 1150-1200°C to 1380-1420°C at a heating rate of 0.5-1.5°C / min, and keeping at 1380-1420°C for 3-5h; heating from 1380-1420°C to 1600-1700°C at a heating rate of 0.75-1°C / min, and keeping at 1600-1700°C for 1-2h; sintering in a slightly positive pressure circulating nitrogen atmosphere, with a nitrogen flow rate of 200-2000mL / min; and a nitrogen pressure of 0.3-2.0MPa.

6. The method for preparing a laminated wide-band wave-transmitting silicon nitride ceramic radome according to claim 1, characterized in that: At least two of the radome ceramic layers have different dielectric constants.

7. The method for preparing a laminated wide-band wave-transmitting silicon nitride ceramic antenna cover according to claim 1, characterized in that: When n=3, The three antenna cover layer data models are a first antenna cover layer data model, a second antenna cover layer data model, and a third antenna cover layer data model which are sequentially connected from the outer wall to the inner wall of the silicon nitride ceramic antenna cover data model; The three radome topology plane layer data models are the first radome topology plane layer data model, the second radome topology plane layer data model, and the third radome topology plane layer data model respectively decomposed into the first radome topology plane layer data model, the second radome topology plane layer data model, and the third radome topology plane layer data model; The three radome layer muds are the first radome layer mud, the second radome layer mud, and the third radome layer mud corresponding to the first radome topology plane layer data model, the second radome layer mud, and the third radome layer mud respectively; The first antenna cover layer slurry comprises silicon nitride powder, rare earth oxide sintering aid, silicon powder, organic additives, and organic solvent in a mass ratio of (90-97): (3-10): (10-30): (20-30): (50-75); The second antenna cover layer slurry comprises silicon nitride powder, rare earth oxide sintering aid, pore former powder, organic additive, and organic solvent in a mass ratio of (90-97): (3-10): (10-30): (20-30): (50-75); The third radome layer slurry comprises silicon nitride powder, rare earth oxide sintering aid, silicon powder, organic additives, and organic solvent in a mass ratio of (90-97): (3-10): (0-30): (10-30): (40-75); The laminated structure broadband wave-transmitting silicon nitride ceramic radome is composed of a first radome ceramic layer, a second radome ceramic layer, and a third radome ceramic layer connected in sequence from the outer wall to the inner wall; The first radome ceramic layer is prepared by first radome layer slurry, the second radome ceramic layer is prepared by second radome layer slurry, and the third radome ceramic layer is prepared by third radome layer slurry; The density of the first antenna cover ceramic layer and the third antenna cover ceramic layer is greater than that of the second antenna cover ceramic layer, and the porosity of the first antenna cover ceramic layer and the third antenna cover ceramic layer is less than that of the second antenna cover ceramic layer; the dielectric constant of the first antenna cover ceramic layer is greater than that of the second antenna cover ceramic layer.