CN117820648A - SiBCN ceramic precursor and preparation method and application thereof - Google Patents
SiBCN ceramic precursor and preparation method and application thereof Download PDFInfo
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- 239000012700 ceramic precursor Substances 0.000 title claims abstract description 60
- 238000002360 preparation method Methods 0.000 title claims abstract description 18
- 239000000919 ceramic Substances 0.000 claims abstract description 78
- FFUAGWLWBBFQJT-UHFFFAOYSA-N hexamethyldisilazane Chemical compound C[Si](C)(C)N[Si](C)(C)C FFUAGWLWBBFQJT-UHFFFAOYSA-N 0.000 claims abstract description 52
- 239000002243 precursor Substances 0.000 claims abstract description 24
- ZDHXKXAHOVTTAH-UHFFFAOYSA-N trichlorosilane Chemical compound Cl[SiH](Cl)Cl ZDHXKXAHOVTTAH-UHFFFAOYSA-N 0.000 claims abstract description 24
- 239000005052 trichlorosilane Substances 0.000 claims abstract description 24
- 238000000034 method Methods 0.000 claims abstract description 19
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 claims abstract description 18
- 229910052796 boron Inorganic materials 0.000 claims abstract description 18
- 239000012298 atmosphere Substances 0.000 claims abstract description 12
- 239000012780 transparent material Substances 0.000 claims abstract description 9
- 238000006068 polycondensation reaction Methods 0.000 claims abstract description 8
- 239000011261 inert gas Substances 0.000 claims abstract description 7
- 239000002994 raw material Substances 0.000 claims abstract description 5
- 239000000463 material Substances 0.000 claims description 29
- 238000004132 cross linking Methods 0.000 claims description 24
- FAQYAMRNWDIXMY-UHFFFAOYSA-N trichloroborane Chemical group ClB(Cl)Cl FAQYAMRNWDIXMY-UHFFFAOYSA-N 0.000 claims description 18
- 238000000197 pyrolysis Methods 0.000 claims description 12
- 235000015895 biscuits Nutrition 0.000 claims description 7
- 238000003756 stirring Methods 0.000 claims description 5
- 238000010438 heat treatment Methods 0.000 claims description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 abstract description 15
- 229910052799 carbon Inorganic materials 0.000 abstract description 15
- 238000006243 chemical reaction Methods 0.000 description 64
- 239000000843 powder Substances 0.000 description 51
- 239000012300 argon atmosphere Substances 0.000 description 38
- 230000000052 comparative effect Effects 0.000 description 22
- 238000003825 pressing Methods 0.000 description 21
- 238000001816 cooling Methods 0.000 description 18
- 238000000227 grinding Methods 0.000 description 18
- 238000005245 sintering Methods 0.000 description 18
- 230000006835 compression Effects 0.000 description 17
- 238000007906 compression Methods 0.000 description 17
- 239000005457 ice water Substances 0.000 description 17
- 239000007788 liquid Substances 0.000 description 13
- 230000000630 rising effect Effects 0.000 description 10
- 230000008569 process Effects 0.000 description 8
- 238000002834 transmittance Methods 0.000 description 8
- 238000002425 crystallisation Methods 0.000 description 7
- 230000008025 crystallization Effects 0.000 description 7
- LIKFHECYJZWXFJ-UHFFFAOYSA-N dimethyldichlorosilane Chemical compound C[Si](C)(Cl)Cl LIKFHECYJZWXFJ-UHFFFAOYSA-N 0.000 description 6
- 238000007789 sealing Methods 0.000 description 5
- 239000005046 Chlorosilane Substances 0.000 description 4
- KOPOQZFJUQMUML-UHFFFAOYSA-N chlorosilane Chemical class Cl[SiH3] KOPOQZFJUQMUML-UHFFFAOYSA-N 0.000 description 4
- 238000010586 diagram Methods 0.000 description 4
- 239000000203 mixture Substances 0.000 description 4
- 238000012986 modification Methods 0.000 description 4
- 230000004048 modification Effects 0.000 description 4
- 230000003647 oxidation Effects 0.000 description 4
- 238000007254 oxidation reaction Methods 0.000 description 4
- 230000009286 beneficial effect Effects 0.000 description 3
- 230000008859 change Effects 0.000 description 3
- 230000007423 decrease Effects 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 239000007789 gas Substances 0.000 description 3
- 239000000376 reactant Substances 0.000 description 3
- 238000001237 Raman spectrum Methods 0.000 description 2
- 238000002441 X-ray diffraction Methods 0.000 description 2
- 230000004075 alteration Effects 0.000 description 2
- 230000005540 biological transmission Effects 0.000 description 2
- IJOOHPMOJXWVHK-UHFFFAOYSA-N chlorotrimethylsilane Chemical compound C[Si](C)(C)Cl IJOOHPMOJXWVHK-UHFFFAOYSA-N 0.000 description 2
- 238000011161 development Methods 0.000 description 2
- 229920000642 polymer Polymers 0.000 description 2
- 230000035484 reaction time Effects 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 description 1
- 235000015842 Hesperis Nutrition 0.000 description 1
- 235000012633 Iberis amara Nutrition 0.000 description 1
- 238000001069 Raman spectroscopy Methods 0.000 description 1
- BLRPTPMANUNPDV-UHFFFAOYSA-N Silane Chemical compound [SiH4] BLRPTPMANUNPDV-UHFFFAOYSA-N 0.000 description 1
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 1
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical group [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 238000009835 boiling Methods 0.000 description 1
- 238000004364 calculation method Methods 0.000 description 1
- 239000000460 chlorine Substances 0.000 description 1
- 229910052801 chlorine Inorganic materials 0.000 description 1
- 125000001309 chloro group Chemical group Cl* 0.000 description 1
- 238000004891 communication Methods 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- ZXSSXAUYKUTLBP-UHFFFAOYSA-N hexane;trichloroborane Chemical compound ClB(Cl)Cl.CCCCCC ZXSSXAUYKUTLBP-UHFFFAOYSA-N 0.000 description 1
- 239000008204 material by function Substances 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 125000002496 methyl group Chemical group [H]C([H])([H])* 0.000 description 1
- 239000002052 molecular layer Substances 0.000 description 1
- 238000005457 optimization Methods 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 230000010363 phase shift Effects 0.000 description 1
- 125000001997 phenyl group Chemical group [H]C1=C([H])C([H])=C(*)C([H])=C1[H] 0.000 description 1
- -1 polytetrafluoroethylene Polymers 0.000 description 1
- 229920001343 polytetrafluoroethylene Polymers 0.000 description 1
- 239000004810 polytetrafluoroethylene Substances 0.000 description 1
- 229910000077 silane Inorganic materials 0.000 description 1
- 229910052814 silicon oxide Inorganic materials 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000012546 transfer Methods 0.000 description 1
- 239000005051 trimethylchlorosilane Substances 0.000 description 1
- 125000000391 vinyl group Chemical group [H]C([*])=C([H])[H] 0.000 description 1
- 229920002554 vinyl polymer Polymers 0.000 description 1
Abstract
The invention discloses a SiBCN ceramic precursor, and a preparation method and application thereof, and belongs to the technical field of wave-transparent materials. The preparation method of the SiBCN ceramic precursor comprises the following steps: under the protection of inert gas atmosphere, trichlorosilane, boron source and hexamethyldisilazane are used as raw materials to carry out polycondensation reaction to prepare the SiBCN ceramic precursor. The SiBCN ceramic precursor prepared by the method has low carbon content, and the SiBCN ceramic prepared by the precursor has excellent wave-transmitting performance.
Description
Technical Field
The invention relates to the technical field of wave-transparent materials, in particular to a SiBCN ceramic precursor, a preparation method and application thereof.
Background
The wave-transmitting material is a multifunctional medium material for protecting the normal operation of the telemetry, guidance, communication and other systems of the aircraft in an extreme working environment. The method has wide application in the fields of carrier rockets, aerospace planes, return satellites, ground radars and the like. The antenna is mainly used in the form of an antenna window and an antenna housing, is used for protecting the radar to work normally in high-speed flight, and is an important channel for sending and receiving signals.
In modern high-tech warfare, missile warfare featuring precision guidance and remote striking profoundly affects the trend of the warfare. Currently, various advanced tactical missiles are faster than Mach four, and sixth generation aircraft are expected to travel at speeds exceeding Mach six. The faster the aircraft speed, the higher the demands on the components. The antenna window/radome is used as a key component in a guidance system, and faces extremely severe high-temperature working environment, and the development lag of the high-temperature-resistant wave-transparent material is one of the bottlenecks for restricting the development of missiles and aircrafts.
The ternary system Si-C-N has poor high temperature resistance, and the temperature for generating crystallization inside is low, so that the crystallization can improve the dielectric constant and dielectric loss of the material, thereby reducing the wave-transparent performance of the material. At present, aiming at Si-C-N or Si-B-C-N systems, chlorosilanes are various in selection, groups linked with silicon atoms in the chlorosilanes comprise a plurality of groups with higher carbon content such as vinyl, methyl, phenyl and the like besides chlorine, and the precursor prepared from the silane is high in carbon content, and electromagnetic wave reflection and loss are enhanced, so that the precursor is not suitable for being used as a wave-transparent material.
Disclosure of Invention
Aiming at the problems, the invention provides a SiBCN ceramic precursor, a preparation method and application thereof, and the prepared SiBCN ceramic precursor has low carbon content and excellent wave-transmitting performance after pyrolysis conversion.
The first object of the invention is to provide a preparation method of SiBCN ceramic precursor, which comprises the following steps:
under the protection of inert gas atmosphere, trichlorosilane, boron source and hexamethyldisilazane are used as raw materials to carry out polycondensation reaction to prepare the SiBCN ceramic precursor.
In one embodiment of the invention, the molar ratio of trichlorosilane, boron source, hexamethyldisilazane is 0.1:0.1:0.36-0.42.
In one embodiment of the invention, the boron source is boron trichloride.
In one embodiment of the invention, the polycondensation reaction is carried out by stirring at room temperature for 8-10 hours, heating to 230-250 ℃ and stirring for 2-2.5 hours.
The second purpose of the invention is to provide SiBCN ceramic prepared by the preparation method.
The third object of the invention is to provide an application of the SiBCN ceramic precursor in preparing SiBCN ceramic wave-transmitting materials.
In one embodiment of the invention, the preparation method of the SiBCN ceramic wave-transparent material comprises the following steps:
under the protection of inert gas atmosphere, the SiBCN precursor is thermally crosslinked at 380-400 ℃ and then pressed into ceramic biscuit, and the ceramic biscuit is pyrolyzed at 1000-1400 ℃ to obtain SiBCN ceramic.
In one embodiment of the invention, the thermal crosslinking time is 3 to 4 hours.
In one embodiment of the invention, the pyrolysis time is 3-4 hours.
The SiBCN ceramic prepared from the ceramic precursor has excellent wave-transmitting performance, and can be applied to the preparation of electromagnetic wave-transmitting materials.
Compared with the prior art, the invention has the following beneficial effects:
according to the invention, the SiBCN ceramic precursor is prepared by taking the trichlorosilane, the boron source and the hexamethyldisilazane as raw materials, and the prepared SiBCN ceramic is characterized in that the trichlorosilane is carbochlorsilane-free, so that the carbon content of the SiBCN ceramic precursor can be obviously reduced, and the SiBCN ceramic prepared by adopting the SiBCN ceramic precursor has good wave-transmitting performance. And boron is introduced into the boron source, and the boron can inhibit crystallization of the material, so that the wave-transmitting performance of SiBCN ceramic is further improved.
The stability and oxidation resistance of the material can be improved by introducing the B element into the Si-C-N ternary system, the material can obtain higher crystallization temperature and ceramic yield, the process of converting the polymer into the ceramic can design the structure of the polymer through a molecular layer, and more performance or a certain property of the ceramic can be endowed, so that the final performance optimization of the ceramic product is realized.
Drawings
FIG. 1 is a graph showing three-dimensional wave-transparent properties of SiBCN ceramic prepared in example 1 at normal temperature;
FIG. 2 is a two-dimensional projection graph of the transmittance of SiBCN ceramic prepared in example 1 at different temperatures, wherein graph a is 25 ℃, graph b is 100 ℃, graph c is 200 ℃, graph d is 300 ℃, graph e is 400 ℃, graph f is 500 ℃, graph g is 600 ℃, graph h is 700 ℃, and graph i is 800 ℃;
FIG. 3 is a graph showing the thermal stability of SiBCN ceramics prepared in example 1-example 5, wherein FIG. a is an argon atmosphere and FIG. b is an air atmosphere;
FIG. 4 is a graph showing the thermal stability of SiCN ceramic prepared in comparative example 6-comparative example 10, wherein FIG. a is an argon atmosphere and FIG. b is an air atmosphere;
FIG. 5 is an XRD pattern of SiCN ceramics prepared in comparative example 6-comparative example 10;
FIG. 6 shows XRD patterns (a) and Raman spectra (b) of SiBCN ceramics prepared in examples 1 to 5.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
The SiBCN ceramic prepared by precursor conversion has the advantages of adjustable dielectric property, simple preparation method and the like, is widely applied to electromagnetic functional materials, is widely researched on wave absorbing performance and electromagnetic shielding performance at present, can be adjusted and controlled according to carbon content and crystallization degree in the materials, and can effectively realize wave absorbing and electromagnetic shielding performance of the materials, but the SiBCN ceramic is rarely researched on wave transmitting performance, especially on high-temperature wave transmitting performance.
Because the carbon-free trichlorosilane is selected as a reactant of the ceramic precursor, the carbon content of the ceramic precursor prepared by the method is obviously reduced compared with that of ceramic precursors prepared by other carbon-containing chlorosilanes, and the SiBCN ceramic prepared by pyrolysis also has lower carbon content. Because the carbon element is a factor for improving the dielectric constant of the material and increasing the dielectric loss, the SiBCN ceramic prepared by the precursor has low carbon content relative to other ceramic precursors, and therefore has lower dielectric constant and dielectric loss, and the wave-transmitting performance is improved. In addition, the invention also introduces boron element to improve the crystallization temperature and inhibit the crystallization of the material, thereby improving the wave-transmitting performance.
The preparation method comprises the following steps of:
under the protection of inert gas atmosphere, performing polycondensation reaction by taking trichlorosilane, boron source and hexamethyldisilazane as raw materials to prepare SiBCN ceramic precursor;
by polycondensation, chlorine atoms in chlorosilanes and boron trichloride and-Si (CH) in hexamethyldisilazane 3 ) 3 The trimethyl chlorosilane with low boiling point is generated by combination, along with the gradual discharge of the product from the reaction system, the reaction is carried out in the positive direction, the molecular weight of the product is gradually increased, and the increase of the reaction temperature by prolonging the reaction time is beneficial to the increase of the molecular weight of the product. And cooling the reactant to room temperature to obtain the ceramic precursor.
In one embodiment of the invention, the molar ratio of trichlorosilane, boron source, hexamethyldisilazane is 0.1:0.1:0.36-0.42.
In one embodiment of the invention, the boron source is boron trichloride.
In one embodiment of the invention, the polycondensation reaction is carried out by stirring at room temperature for 8-10 hours and at a temperature of 230-250℃for 2-2.5 hours.
In the invention, too high temperature and too long reaction time can lead to the precursor to crosslink in advance, too low temperature or too short time can lead to the precursor polyborosilazane molecular weight to be too small, which is unfavorable for preparing the ceramic precursor, but the time extension can not compensate the influence caused by too low reaction temperature, and the reaction can not be further carried out in the forward direction at low temperature.
The SiBCN ceramic precursor prepared by the method can be used for preparing a wave-transmitting material.
The SiBCN ceramic wave-transmitting material is prepared according to the following steps:
under the protection of inert gas atmosphere, the SiBCN ceramic precursor is thermally crosslinked at 380-400 ℃ and then pressed into ceramic biscuit, and the ceramic biscuit is pyrolyzed at 1000-1400 ℃ to obtain the SiBCN ceramic wave-transmitting material.
The SiBCN ceramic precursor is subjected to thermal crosslinking at 380-400 ℃, namely a preliminary crosslinking process, and the aim of the step is to: a. the sensitive active groups are subjected to chemical reaction, the precursor is converted from a liquid state to a solid state, and the precursor is insensitive to air; b. the precursor can release gas in the pyrolysis process, and the process is favorable for reducing the release of the gas in the sintering process after pressing, so that the material is easier to form; c. is beneficial to improving the ceramic yield;
in the pressing process, the invention adopts the pressure of 10-13 tons, so long as the pressure can be used for pressing into blanks, the pressure change does not greatly influence the performance, the thickness of the material can influence the wave-transmitting performance of the material, the thickness of the ceramic biscuit is 1-10mm, and the thickness required to be pressed can be selected according to the wave-transmitting performance of SiBCN ceramics.
In the pyrolysis process, the precursor is converted from organic to inorganic with the increase of temperature, chemical bonds are broken and recombined, and in the process, the material can release gas and shrink to a certain extent, so that the inorganic SiBCN ceramic is finally generated.
In one embodiment of the invention, the thermal crosslinking time is 3 to 4 hours. Too low a temperature and too short a time result in incomplete thermal crosslinking, too high a temperature results in excessive crosslinking, and organic to inorganic conversion may occur, resulting in difficulty in pressing, typically for 3 to 4 hours.
In one embodiment of the invention, the pyrolysis time of 3-4 hours is an empirical value and has no definite effect on the time, but too short a material may not be completely converted, and longer times should have less effect on the material properties.
Further description is provided below in connection with specific embodiments.
In the following examples, all materials are commercially available unless otherwise specified. The boron trichloride solution used in the invention is purchased and obtained, and the boron trichloride solution is 1.0mol/L boron trichloride hexane solution.
Example 1
Step 1, the whole reaction process is carried out under the protection of argon atmosphere, and 100ml of 1.0mol/L boron trichloride solution and 13.545g of 0.1mol of trichlorosilane are added into a flask filled with a magneton. Then, the temperature is controlled to be about 0 ℃ under the condition of ice-water bath, 67.535g and 0.42mol of hexamethyldisilazane are slowly added by a syringe, stirred for 8 hours, and kept at the temperature rising rate of 50 ℃/h for 2 hours, and the white liquid SiBCN ceramic precursor is obtained after the reaction is completed.
And 2, rapidly transferring the SiBCN ceramic precursor into a tube furnace, raising the temperature to 400 ℃ at a speed of 2 ℃/min under argon atmosphere, preserving heat for 4 hours for primary crosslinking, cooling to room temperature, grinding the powder by a ball mill until the powder can pass through a 200-mesh screen, pressing the powder into a green body by a compression mold, and sintering the green body at 1000 ℃ for 4 hours to obtain SiBCN ceramic, which is recorded as SiBCN-1000 ℃.
Example 2
Step 1, the whole reaction process is carried out under the protection of argon atmosphere, and 100ml of 1.0mol/L boron trichloride solution and 13.545g of 0.1mol of trichlorosilane are added into a flask filled with a magneton. Then, the temperature is controlled to be about 0 ℃ under the condition of ice-water bath, 67.535g and 0.42mol of hexamethyldisilazane are slowly added by a syringe, stirred for 8 hours, and kept at the temperature rising rate of 50 ℃/h for 2 hours, and the white liquid SiBCN ceramic precursor is obtained after the reaction is completed.
And 2, rapidly transferring the SiBCN ceramic precursor into a tube furnace, raising the temperature to 400 ℃ at a speed of 2 ℃/min under argon atmosphere, preserving heat for 4 hours for primary crosslinking, cooling to room temperature, grinding the powder by a ball mill until the powder can pass through a 200-mesh screen, pressing the powder into a green body by a compression mold, and sintering the green body at 1100 ℃ for 4 hours to obtain SiBCN ceramic, which is marked as SiBCN-1100 ℃.
Example 3
Step 1, the whole reaction process is carried out under the protection of argon atmosphere, and 100ml of 1.0mol/L boron trichloride solution and 13.545g of 0.1mol of trichlorosilane are added into a flask filled with a magneton. Then, the temperature is controlled to be about 0 ℃ under the condition of ice-water bath, 67.535g and 0.42mol of hexamethyldisilazane are slowly added by a syringe, stirred for 8 hours, and kept at the temperature rising rate of 50 ℃/h for 2 hours, and the white liquid SiBCN ceramic precursor is obtained after the reaction is completed.
Step 2, rapidly transferring the SiBCN ceramic precursor into a tube furnace, raising the temperature to 400 ℃ at a speed of 2 ℃/min under argon atmosphere, preserving heat for 4 hours for primary crosslinking, cooling to room temperature, grinding the powder by a ball mill until the powder can pass through a 200-mesh screen, pressing the powder into a green body by a compression mold, and sintering the green body at 1200 ℃ for 4 hours to obtain SiBCN ceramic, which is recorded as SiBCN-1200 ℃.
Example 4
Step 1, the whole reaction process is carried out under the protection of argon atmosphere, and 100ml of 1.0mol/L boron trichloride solution and 13.545g of 0.1mol of trichlorosilane are added into a flask filled with a magneton. Then, the temperature is controlled to be about 0 ℃ under the condition of ice-water bath, 67.535g and 0.42mol of hexamethyldisilazane are slowly added by a syringe, stirred for 8 hours, and kept at the temperature rising rate of 50 ℃/h for 2 hours, and the white liquid SiBCN ceramic precursor is obtained after the reaction is completed.
And 2, rapidly transferring the SiBCN ceramic precursor into a tube furnace, raising the temperature to 400 ℃ at a speed of 2 ℃/min under argon atmosphere, preserving heat for 4 hours for primary crosslinking, cooling to room temperature, grinding the powder by a ball mill until the powder can pass through a 200-mesh screen, pressing the powder into a green body by a compression mold, and sintering the green body at 1300 ℃ for 4 hours to obtain SiBCN ceramic, which is recorded as SiBCN-1300 ℃.
Example 5
Step 1, the whole reaction process is carried out under the protection of argon atmosphere, and 100ml of 1.0mol/L boron trichloride solution and 13.545g of 0.1mol of trichlorosilane are added into a flask filled with a magneton. Then, the temperature is controlled to be about 0 ℃ under the condition of ice-water bath, 67.535g and 0.42mol of hexamethyldisilazane are slowly added by a syringe, stirred for 8 hours, and kept at the temperature rising rate of 50 ℃/h for 2 hours, and the white liquid SiBCN ceramic precursor is obtained after the reaction is completed.
Step 2, rapidly transferring the SiBCN ceramic precursor into a tube furnace, raising the temperature to 400 ℃ at a speed of 2 ℃/min under argon atmosphere, preserving heat for 4 hours for primary crosslinking, cooling to room temperature, grinding the powder by a ball mill until the powder can pass through a 200-mesh screen, pressing the powder into a green body by a compression mold, and sintering the green body at 1400 ℃ for 4 hours to obtain SiBCN ceramic, which is recorded as SiBCN-1400 ℃.
Example 6
Step 1, the whole reaction process is carried out under the protection of argon atmosphere, and 100ml of 1.0mol/L boron trichloride solution and 13.545g of 0.1mol of trichlorosilane are added into a flask filled with a magneton. Then, the temperature is controlled to be about 0 ℃ under the condition of ice-water bath, 58.1g and 0.36mol of hexamethyldisilazane are slowly added by a syringe, the mixture is stirred for 10 hours, the temperature is increased by 230 ℃ at the speed of 50 ℃/h, the mixture is kept for 2.5 hours, and the white liquid SiBCN ceramic precursor is obtained after the reaction is completed.
And 2, rapidly transferring the SiBCN ceramic precursor into a tube furnace, raising the temperature to 380 ℃ at a speed of 2 ℃/min under argon atmosphere, preserving heat for 3 hours for primary crosslinking, cooling to room temperature, grinding the powder by a ball mill until the powder can pass through a 200-mesh screen, pressing the powder into a blank by a compression mold, and sintering at 1000 ℃ for 3 hours to obtain the SiBCN ceramic.
Example 7
Step 1, the whole reaction process is carried out under the protection of argon atmosphere, and 100ml of 1.0mol/L boron trichloride solution and 13.545g of 0.1mol of trichlorosilane are added into a flask filled with a magneton. Then, the temperature is controlled to be about 0 ℃ under the condition of ice-water bath, 64.556g and 0.40mol of hexamethyldisilazane are slowly added by a syringe, the mixture is stirred for 9 hours, the temperature is increased by 240 ℃ at the speed of 50 ℃/h, the mixture is kept for 2.3 hours, and the white liquid SiBCN ceramic precursor is obtained after the reaction is completed.
And 2, rapidly transferring the SiBCN ceramic precursor into a tube furnace, raising the temperature to 390 ℃ at a speed of 2 ℃/min under argon atmosphere, preserving heat for 3.5 hours for primary crosslinking, cooling to room temperature, grinding the powder by a ball mill until the powder can pass through a 200-mesh screen, pressing the powder into a blank by a compression mold, and sintering at 1100 ℃ for 3.5 hours to obtain the SiBCN ceramic.
Comparative example 1
Step 1, the whole reaction process is carried out under the protection of argon atmosphere, 100mL of 1.0mol/L boron trichloride solution is firstly added under the ice water bath condition of 0 ℃, then 0.1mol of dimethyl dichlorosilane is added, and 57.74g of hexamethyldisilazane is added into a reaction bottle. And (3) sealing the reaction bottle, slowly increasing the reaction temperature after the reaction bottle is heated to room temperature, and keeping the reaction bottle at 250 ℃ for 2 hours to obtain the precursor.
And 2, rapidly transferring the precursor into a tube furnace, raising the temperature to 400 ℃ at a speed of 2 ℃/min under argon atmosphere, preserving heat for 4 hours for preliminary crosslinking, cooling to room temperature, grinding the powder by a ball mill until the powder can pass through a 200-mesh screen, pressing the powder into a blank by a compression mold, and sintering at 1000 ℃ for 4 hours to obtain SiBCN ceramic.
Comparative example 2
Step 1, the whole reaction process is carried out under the protection of argon atmosphere, 100mL of 1.0mol/L boron trichloride solution is firstly added under the ice water bath condition of 0 ℃, then 0.1mol of dimethyl dichlorosilane is added, and 57.74g of hexamethyldisilazane is added into a reaction bottle. And (3) sealing the reaction bottle, slowly increasing the reaction temperature after the reaction bottle is heated to room temperature, and keeping the reaction bottle at 250 ℃ for 2 hours to obtain the precursor.
And 2, rapidly transferring the precursor into a tube furnace, raising the temperature to 400 ℃ at a speed of 2 ℃/min under argon atmosphere, preserving heat for 4 hours for preliminary crosslinking, cooling to room temperature, grinding the powder by a ball mill until the powder can pass through a 200-mesh screen, pressing the powder into a blank by a compression mold, and sintering at 1100 ℃ for 4 hours to obtain SiBCN ceramic.
Comparative example 3
Step 1, the whole reaction process is carried out under the protection of argon atmosphere, 100mL of 1.0mol/L boron trichloride solution is firstly added under the ice water bath condition of 0 ℃, then 0.1mol of dimethyl dichlorosilane is added, and 57.74g of hexamethyldisilazane is added into a reaction bottle. And (3) sealing the reaction bottle, slowly increasing the reaction temperature after the reaction bottle is heated to room temperature, and keeping the reaction bottle at 250 ℃ for 2 hours to obtain the precursor.
And 2, rapidly transferring the precursor into a tube furnace, raising the temperature to 400 ℃ at a speed of 2 ℃/min under argon atmosphere, preserving heat for 4 hours for preliminary crosslinking, cooling to room temperature, grinding the powder by a ball mill until the powder can pass through a 200-mesh screen, pressing the powder into a blank by a compression mold, and sintering at 1200 ℃ for 4 hours to obtain SiBCN ceramic.
Comparative example 4
Step 1, the whole reaction process is carried out under the protection of argon atmosphere, 100mL of 1.0mol/L boron trichloride solution is firstly added under the ice water bath condition of 0 ℃, then 0.1mol of dimethyl dichlorosilane is added, and 57.74g of hexamethyldisilazane is added into a reaction bottle. And (3) sealing the reaction bottle, slowly increasing the reaction temperature after the reaction bottle is heated to room temperature, and keeping the reaction bottle at 250 ℃ for 2 hours to obtain the precursor.
And 2, rapidly transferring the precursor into a tube furnace, raising the temperature to 400 ℃ at a speed of 2 ℃/min under argon atmosphere, preserving heat for 4 hours for preliminary crosslinking, cooling to room temperature, grinding the powder by a ball mill until the powder can pass through a 200-mesh screen, pressing the powder into a blank by a compression mold, and sintering the blank at 1300 ℃ for 4 hours to obtain SiBCN ceramic.
Comparative example 5
Step 1, the whole reaction process is carried out under the protection of argon atmosphere, 100mL of 1.0mol/L boron trichloride solution is firstly added under the ice water bath condition of 0 ℃, then 0.1mol of dimethyl dichlorosilane is added, and 57.74g of hexamethyldisilazane is added into a reaction bottle. And (3) sealing the reaction bottle, slowly increasing the reaction temperature after the reaction bottle is heated to room temperature, and keeping the reaction bottle at 250 ℃ for 2 hours to obtain the precursor.
And 2, rapidly transferring the precursor into a tube furnace, raising the temperature to 400 ℃ at a speed of 2 ℃/min under argon atmosphere, preserving heat for 4 hours for preliminary crosslinking, cooling to room temperature, grinding the powder by a ball mill until the powder can pass through a 200-mesh screen, pressing the powder into a blank by a compression mold, and sintering at 1400 ℃ for 4 hours to obtain SiBCN ceramic.
Comparative example 6
The whole reaction was carried out under the protection of argon atmosphere, and 13.545g, 0.1mol of trichlorosilane was added to the flask containing the magneton. Then, the temperature is controlled to be about 0 ℃ under the condition of ice-water bath, 67.535g and 0.42mol of hexamethyldisilazane are slowly added by a syringe, stirred for 8 hours, and kept at the temperature rising rate of 50 ℃/h for 2 hours, and the white liquid SiCN ceramic precursor is obtained after the reaction is completed.
Rapidly transferring the SiCN ceramic precursor into a tube furnace, raising the temperature to 400 ℃ at a speed of 2 ℃/min under argon atmosphere, preserving the heat for 4 hours for preliminary crosslinking, cooling to room temperature, grinding the powder by a ball mill until the powder can pass through a 200-mesh screen, pressing the powder into a green body by a compression mold, and sintering the green body at 1000 ℃ for 4 hours to obtain SiCN ceramic, which is marked as SiCN-1000 ℃.
Comparative example 7
The whole reaction was carried out under the protection of argon atmosphere, and 13.545g, 0.1mol of trichlorosilane was added to the flask containing the magneton. Then, the temperature is controlled to be about 0 ℃ under the condition of ice-water bath, 67.535g and 0.42mol of hexamethyldisilazane are slowly added by a syringe, stirred for 8 hours, and kept at the temperature rising rate of 50 ℃/h for 2 hours, and the white liquid SiCN ceramic precursor is obtained after the reaction is completed.
Rapidly transferring the SiCN ceramic precursor into a tube furnace, raising the temperature to 400 ℃ at a speed of 2 ℃/min under argon atmosphere, preserving the heat for 4 hours for preliminary crosslinking, cooling to room temperature, grinding the powder by a ball mill until the powder can pass through a 200-mesh screen, pressing the powder into a green body by a compression mold, and sintering the green body at 1100 ℃ for 4 hours to obtain SiCN ceramic, which is marked as SiCN-1100 ℃.
Comparative example 8
The whole reaction was carried out under the protection of argon atmosphere, and 13.545g, 0.1mol of trichlorosilane was added to the flask containing the magneton. Then, the temperature is controlled to be about 0 ℃ under the condition of ice-water bath, 67.535g and 0.42mol of hexamethyldisilazane are slowly added by a syringe, stirred for 8 hours, and kept at the temperature rising rate of 50 ℃/h for 2 hours, and the white liquid SiCN ceramic precursor is obtained after the reaction is completed.
Rapidly transferring the SiCN ceramic precursor into a tube furnace, raising the temperature to 400 ℃ at a speed of 2 ℃/min under argon atmosphere, preserving the heat for 4 hours for preliminary crosslinking, cooling to room temperature, grinding the powder by a ball mill until the powder can pass through a 200-mesh screen, pressing the powder into a green body by a compression mold, and sintering the green body at 1200 ℃ for 4 hours to obtain SiCN ceramic, which is marked as SiCN-1200 ℃.
Comparative example 9
The whole reaction was carried out under the protection of argon atmosphere, and 13.545g, 0.1mol of trichlorosilane was added to the flask containing the magneton. Then, the temperature is controlled to be about 0 ℃ under the condition of ice-water bath, 67.535g and 0.42mol of hexamethyldisilazane are slowly added by a syringe, stirred for 8 hours, and kept at the temperature rising rate of 50 ℃/h for 2 hours, and the white liquid SiCN ceramic precursor is obtained after the reaction is completed.
Rapidly transferring the SiCN ceramic precursor into a tube furnace, raising the temperature to 400 ℃ at a speed of 2 ℃/min under argon atmosphere, preserving the heat for 4 hours for preliminary crosslinking, cooling to room temperature, grinding the powder by a ball mill until the powder can pass through a 200-mesh screen, pressing the powder into a green body by a compression mold, and sintering the green body at 1300 ℃ for 4 hours to obtain SiCN ceramic, which is marked as SiCN-1300 ℃.
Comparative example 10
The whole reaction was carried out under the protection of argon atmosphere, and 13.545g, 0.1mol of trichlorosilane was added to the flask containing the magneton. Then, the temperature is controlled to be about 0 ℃ under the condition of ice-water bath, 67.535g and 0.42mol of hexamethyldisilazane are slowly added by a syringe, stirred for 8 hours, and kept at the temperature rising rate of 50 ℃/h for 2 hours, and the white liquid SiCN ceramic precursor is obtained after the reaction is completed.
Rapidly transferring the SiCN ceramic precursor into a tube furnace, raising the temperature to 400 ℃ at a speed of 2 ℃/min under argon atmosphere, preserving the heat for 4 hours for preliminary crosslinking, cooling to room temperature, grinding the powder by a ball mill until the powder can pass through a 200-mesh screen, pressing the powder into a green body by a compression mold, and sintering the green body at 1400 ℃ for 4 hours to obtain SiCN ceramic, which is marked as SiCN-1400 ℃.
The detection method of the wave transmission performance comprises the following steps: the electromagnetic parameters of the ceramic sample are measured by adopting a vector network analyzer manufactured by Anristu corporation of Japan, the model is MS4644A, the method is a waveguide method, the frequency band is X-band (8.2-12.4 GHz), and the Ku-band (12.4-18 GHz). Grinding a sample to be measured into standard size of 22.86mm multiplied by 10.15mm, calibrating an instrument by using a polytetrafluoroethylene standard sample before measurement, and then measuring parameters such as a real part, an imaginary part and the like of a relative dielectric constant of a ceramic sample, wherein the wave transmission performance is calculated according to the dielectric constant, and the specific calculation method is as follows;
generally, for wave-transparent materials, the power transfer coefficient-T 2 And (i.e., wave transmissivity), power reflection coefficient-R 2 The relationship between-and the loss a of electromagnetic waves in the ceramic (mainly heat loss) is expressed as:
│T 2 │+│R 2 │+A＝1
assuming that the medium is a non-consumable medium, taking a horizontally polarized electromagnetic wave as an example, the electromagnetic wave energy loss A, the power reflection coefficient r and the wave transmittance I T I 2 Can be expressed as:
Aπ＝(2πd/λ)[(εtgδ)/(δ-sin 2 θ) 1/2 ] (3-1)
r＝(1-n ab )/(1+n ab ) (3-2)
wherein the refractive index n ab ＝εcosθ/(ε-sin 2 θ) 1/2
Phase shift is caused by the incident wave passing through the dielectric slab with the thickness d at one time.
Wherein: d- -plate thickness; lambda- -wavelength; θ—angle of incidence; epsilon-dielectric constant; tg delta-dielectric loss tangent;
fig. 1 is a three-dimensional wave-transmitting performance diagram of the SiBCN ceramic prepared in example 1 at normal temperature, and it can be seen from the diagram that the SiBCN ceramic can achieve a wave-transmitting rate of more than 90% below 2mm, and can achieve a wave-transmitting rate of more than 80%, a minimum wave-transmitting rate of 79.69% and an average wave-transmitting rate of 90.56% basically under the condition of a full-band 1-10mm thickness of an X-band (8.2-12.4 GHz).
TABLE 1 wave-transparent Properties of SiBCN ceramics prepared in example 1 at different temperatures
Fig. 2 is a two-dimensional projection diagram of the wave transmittance of the SiBCN ceramic prepared in example 1 at different temperatures, and it can be seen from table 1 and fig. 2 that, as the test temperature increases, the wave transmittance of the ceramic also gradually decreases, and in the two-dimensional diagram, the range of the wave transmittance greater than 90% gradually decreases, and the average wave transmittance also gradually decreases, but in all temperature ranges, the higher wave transmittance can be maintained.
TABLE 2 wave-transparent Properties of example 1-example 5 at different pyrolysis temperatures
Table 3 comparative examples 1-5 wave-transparent properties at different pyrolysis temperatures
| Comparative example 1 | Comparative example 2 | Comparative example 3 | Comparative example 4 | Comparative example 5 | |
| Minimum transmittance | 69.67％ | 69.20％ | 67.37％ | 61.82％ | 54.02 |
Tables 2 and 3 show the wave-transmitting properties of examples 1 to 5 and comparative examples 1 to 5, respectively, tested at 25 c, and it can be seen that the wave-transmitting rate of the SiBCN ceramics prepared with dimethyldichlorosilane of comparative examples 1 to 5 is significantly lower than that of the SiBCN ceramics prepared with trichlorosilane of examples 1 to 5. The carbon element is a factor for improving the dielectric constant and increasing the dielectric loss of the material, and is unfavorable for improving the wave-transmitting performance, so that the invention further shows that the carbon-free trichlorosilane is adopted as a precursor reactant to have low carbon content and lower dielectric constant and dielectric loss, thereby improving the wave-transmitting performance of SiBCN ceramic.
FIG. 3 is a graph showing the thermal stability of SiBCN ceramic prepared in example 1, and it can be seen from FIG. 3 that SiBCN ceramic is not decomposed at 1400 ℃ under argon atmosphere, oxidized at a temperature exceeding 1200 ℃ and gained by < 5% at 1400 ℃ under oxygen atmosphere.
FIG. 4 is a graph showing the thermal stability of SiCN ceramics prepared in comparative example 6-comparative example 10. As can be seen from fig. 4, the SiCN ceramic has a relatively large mass change in an argon atmosphere, and a mass loss of 3.2% -4.8% and a relatively large mass loss. From the graph (b), it can be seen that the mass increase of SiCN ceramic is also more remarkable in the air atmosphere, the mass increase is between 6.27% and 14.90%, but the mass change is not large before 1000 ℃ and is only between 0.2% and 1.6%, which indicates that SiCN ceramic has good high temperature stability before 1000 ℃, the high temperature oxidation resistance after 1000 ℃ is drastically reduced, and the mass increase after 1000 ℃ is derived from the oxidation of SiN phase to SiOx in the air atmosphere. The method proves that the B element is introduced into the prepared SiBCN ceramic prepared by the pyrolysis conversion of polyborosilazane, so that the defects of poor high temperature resistance and oxidation resistance of the SiCN ceramic are well overcome.
To further investigate the effect of boron addition on the wave-transmitting properties of SiBCN ceramics, XRD and raman tests were performed on the materials prepared in examples 1 to 5 and comparative examples 1 to 5, and as can be seen from fig. 5, siC crystals were already generated at a pyrolysis temperature of 1400 ℃ without boron addition during the preparation, so that the wave-transmitting properties were not favored.
The SiBCN ceramic is not crystallized at 1400 ℃ due to the addition of boron (a graph of FIG. 6), and I is seen from a Raman spectrum of a graph b of FIG. 6 with the increase of pyrolysis temperature D /I G The increase in sp2 carbon proves that sp2 carbon contributes to an increase in the dielectric constant of the material, thereby reducing the wave-transmitting rate of the material.
While preferred embodiments of the present invention have been described, additional variations and modifications in those embodiments may occur to those skilled in the art once they learn of the basic inventive concepts. It is therefore intended that the following claims be interpreted as including the preferred embodiments and all such alterations and modifications as fall within the scope of the invention.
It will be apparent to those skilled in the art that various modifications and variations can be made to the present invention without departing from the spirit or scope of the invention. Thus, it is intended that the present invention also include such modifications and alterations insofar as they come within the scope of the appended claims or the equivalents thereof.
Claims (9)
1. The preparation method of the SiBCN ceramic precursor is characterized by comprising the following steps of:
under the protection of inert gas atmosphere, trichlorosilane, boron source and hexamethyldisilazane are used as raw materials to carry out polycondensation reaction to prepare the SiBCN ceramic precursor.
2. The method for preparing the SiBCN ceramic precursor according to claim 1, wherein the molar ratio of trichlorosilane to boron source to hexamethyldisilazane is 0.1:0.1:0.36-0.42.
3. The method for preparing a SiBCN ceramic precursor according to claim 1, wherein the boron source is boron trichloride.
4. The method for preparing a SiBCN ceramic precursor according to claim 1, wherein the polycondensation is carried out by stirring at room temperature for 8-10h, heating to 230-250 ℃ and stirring for 2-2.5h.
5. A SiBCN ceramic precursor prepared by the method of any one of claims 1-4.
6. Use of the SiBCN ceramic precursor of claim 5 in the preparation of a wave-transparent material.
7. The application of the SiBCN ceramic precursor in preparing the SiBCN ceramic wave-transmitting material according to claim 6, wherein the preparation method of the SiBCN ceramic wave-transmitting material comprises the following steps:
under the protection of inert gas atmosphere, the SiBCN precursor of claim 5 is thermally crosslinked at 380-400 ℃ and then pressed into ceramic biscuit, and the ceramic biscuit is pyrolyzed at 1000-1400 ℃ to obtain SiBCN ceramic.
8. The use of a SiBCN ceramic precursor according to claim 7 for the preparation of SiBCN ceramic wave-transparent material, wherein the thermal cross-linking time is 3-4h.
9. The use of a SiBCN ceramic precursor according to claim 7 for the preparation of SiBCN ceramic wave-transparent material, characterized in that the pyrolysis time is 3-4h.
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