CN115573056A - Low-oxygen silicon carbide fiber and preparation method thereof - Google Patents
Low-oxygen silicon carbide fiber and preparation method thereof Download PDFInfo
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- CN115573056A CN115573056A CN202211181090.XA CN202211181090A CN115573056A CN 115573056 A CN115573056 A CN 115573056A CN 202211181090 A CN202211181090 A CN 202211181090A CN 115573056 A CN115573056 A CN 115573056A
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- 239000000835 fiber Substances 0.000 title claims abstract description 105
- HBMJWWWQQXIZIP-UHFFFAOYSA-N silicon carbide Chemical compound [Si+]#[C-] HBMJWWWQQXIZIP-UHFFFAOYSA-N 0.000 title claims abstract description 69
- 229910010271 silicon carbide Inorganic materials 0.000 title claims abstract description 69
- 239000001301 oxygen Substances 0.000 title claims abstract description 39
- 229910052760 oxygen Inorganic materials 0.000 title claims abstract description 39
- 238000002360 preparation method Methods 0.000 title claims abstract description 22
- 238000009987 spinning Methods 0.000 claims abstract description 51
- 229920003257 polycarbosilane Polymers 0.000 claims abstract description 45
- 238000000034 method Methods 0.000 claims abstract description 41
- 125000004093 cyano group Chemical group *C#N 0.000 claims abstract description 34
- 238000001035 drying Methods 0.000 claims abstract description 17
- 239000002994 raw material Substances 0.000 claims abstract description 10
- 238000005245 sintering Methods 0.000 claims abstract description 8
- 229920001187 thermosetting polymer Polymers 0.000 claims abstract description 8
- 150000001875 compounds Chemical class 0.000 claims abstract description 3
- 238000010438 heat treatment Methods 0.000 claims description 31
- WYURNTSHIVDZCO-UHFFFAOYSA-N Tetrahydrofuran Chemical compound C1CCOC1 WYURNTSHIVDZCO-UHFFFAOYSA-N 0.000 claims description 26
- 239000012298 atmosphere Substances 0.000 claims description 16
- CSCPPACGZOOCGX-UHFFFAOYSA-N Acetone Chemical compound CC(C)=O CSCPPACGZOOCGX-UHFFFAOYSA-N 0.000 claims description 15
- 239000002904 solvent Substances 0.000 claims description 14
- 238000000578 dry spinning Methods 0.000 claims description 13
- YLQBMQCUIZJEEH-UHFFFAOYSA-N tetrahydrofuran Natural products C=1C=COC=1 YLQBMQCUIZJEEH-UHFFFAOYSA-N 0.000 claims description 13
- ZMXDDKWLCZADIW-UHFFFAOYSA-N N,N-Dimethylformamide Chemical compound CN(C)C=O ZMXDDKWLCZADIW-UHFFFAOYSA-N 0.000 claims description 12
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 10
- 238000010041 electrostatic spinning Methods 0.000 claims description 10
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 9
- CTQNGGLPUBDAKN-UHFFFAOYSA-N O-Xylene Chemical compound CC1=CC=CC=C1C CTQNGGLPUBDAKN-UHFFFAOYSA-N 0.000 claims description 8
- VLKZOEOYAKHREP-UHFFFAOYSA-N n-Hexane Chemical compound CCCCCC VLKZOEOYAKHREP-UHFFFAOYSA-N 0.000 claims description 8
- 238000001723 curing Methods 0.000 claims description 7
- YXFVVABEGXRONW-UHFFFAOYSA-N Toluene Chemical compound CC1=CC=CC=C1 YXFVVABEGXRONW-UHFFFAOYSA-N 0.000 claims description 6
- BDERNNFJNOPAEC-UHFFFAOYSA-N propan-1-ol Chemical compound CCCO BDERNNFJNOPAEC-UHFFFAOYSA-N 0.000 claims description 6
- 229910052742 iron Inorganic materials 0.000 claims description 5
- 239000003960 organic solvent Substances 0.000 claims description 5
- HEDRZPFGACZZDS-UHFFFAOYSA-N Chloroform Chemical compound ClC(Cl)Cl HEDRZPFGACZZDS-UHFFFAOYSA-N 0.000 claims description 4
- KFZMGEQAYNKOFK-UHFFFAOYSA-N Isopropanol Chemical compound CC(C)O KFZMGEQAYNKOFK-UHFFFAOYSA-N 0.000 claims description 4
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 claims description 4
- 229910052782 aluminium Inorganic materials 0.000 claims description 4
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims description 4
- 238000010304 firing Methods 0.000 claims description 4
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 claims description 2
- XBDQKXXYIPTUBI-UHFFFAOYSA-M Propionate Chemical compound CCC([O-])=O XBDQKXXYIPTUBI-UHFFFAOYSA-M 0.000 claims description 2
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 claims description 2
- QCWXUUIWCKQGHC-UHFFFAOYSA-N Zirconium Chemical compound [Zr] QCWXUUIWCKQGHC-UHFFFAOYSA-N 0.000 claims description 2
- 229910052796 boron Inorganic materials 0.000 claims description 2
- 239000010941 cobalt Substances 0.000 claims description 2
- 229910017052 cobalt Inorganic materials 0.000 claims description 2
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 claims description 2
- WBJINCZRORDGAQ-UHFFFAOYSA-N formic acid ethyl ester Natural products CCOC=O WBJINCZRORDGAQ-UHFFFAOYSA-N 0.000 claims description 2
- 239000011261 inert gas Substances 0.000 claims description 2
- 229910052746 lanthanum Inorganic materials 0.000 claims description 2
- FZLIPJUXYLNCLC-UHFFFAOYSA-N lanthanum atom Chemical compound [La] FZLIPJUXYLNCLC-UHFFFAOYSA-N 0.000 claims description 2
- 238000004519 manufacturing process Methods 0.000 claims description 2
- 229910052759 nickel Inorganic materials 0.000 claims description 2
- 229910052758 niobium Inorganic materials 0.000 claims description 2
- 239000010955 niobium Substances 0.000 claims description 2
- GUCVJGMIXFAOAE-UHFFFAOYSA-N niobium atom Chemical compound [Nb] GUCVJGMIXFAOAE-UHFFFAOYSA-N 0.000 claims description 2
- 238000001029 thermal curing Methods 0.000 claims description 2
- 239000010936 titanium Substances 0.000 claims description 2
- 229910052719 titanium Inorganic materials 0.000 claims description 2
- 239000008096 xylene Substances 0.000 claims description 2
- 229910052727 yttrium Inorganic materials 0.000 claims description 2
- VWQVUPCCIRVNHF-UHFFFAOYSA-N yttrium atom Chemical compound [Y] VWQVUPCCIRVNHF-UHFFFAOYSA-N 0.000 claims description 2
- 229910052726 zirconium Inorganic materials 0.000 claims description 2
- OBNDGIHQAIXEAO-UHFFFAOYSA-N [O].[Si] Chemical compound [O].[Si] OBNDGIHQAIXEAO-UHFFFAOYSA-N 0.000 claims 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 19
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 16
- 239000012300 argon atmosphere Substances 0.000 description 16
- 239000002243 precursor Substances 0.000 description 9
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 8
- 229910052786 argon Inorganic materials 0.000 description 8
- 239000007789 gas Substances 0.000 description 8
- 238000006243 chemical reaction Methods 0.000 description 7
- 238000002844 melting Methods 0.000 description 5
- 230000008018 melting Effects 0.000 description 5
- 229910052757 nitrogen Inorganic materials 0.000 description 4
- OZAIFHULBGXAKX-UHFFFAOYSA-N 2-(2-cyanopropan-2-yldiazenyl)-2-methylpropanenitrile Chemical compound N#CC(C)(C)N=NC(C)(C)C#N OZAIFHULBGXAKX-UHFFFAOYSA-N 0.000 description 3
- NLHHRLWOUZZQLW-UHFFFAOYSA-N Acrylonitrile Chemical compound C=CC#N NLHHRLWOUZZQLW-UHFFFAOYSA-N 0.000 description 3
- 238000004821 distillation Methods 0.000 description 3
- 238000012986 modification Methods 0.000 description 3
- 230000004048 modification Effects 0.000 description 3
- 239000003054 catalyst Substances 0.000 description 2
- 230000000052 comparative effect Effects 0.000 description 2
- 238000005336 cracking Methods 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- BLRPTPMANUNPDV-UHFFFAOYSA-N Silane Chemical compound [SiH4] BLRPTPMANUNPDV-UHFFFAOYSA-N 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 238000004132 cross linking Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 238000010894 electron beam technology Methods 0.000 description 1
- 238000005194 fractionation Methods 0.000 description 1
- 230000005251 gamma ray Effects 0.000 description 1
- 238000013007 heat curing Methods 0.000 description 1
- 238000006459 hydrosilylation reaction Methods 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 229920000642 polymer Polymers 0.000 description 1
- 239000011148 porous material Substances 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- QBERHIJABFXGRZ-UHFFFAOYSA-M rhodium;triphenylphosphane;chloride Chemical compound [Cl-].[Rh].C1=CC=CC=C1P(C=1C=CC=CC=1)C1=CC=CC=C1.C1=CC=CC=C1P(C=1C=CC=CC=1)C1=CC=CC=C1.C1=CC=CC=C1P(C=1C=CC=CC=1)C1=CC=CC=C1 QBERHIJABFXGRZ-UHFFFAOYSA-M 0.000 description 1
- 229910000077 silane Inorganic materials 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 239000013589 supplement Substances 0.000 description 1
- 238000003786 synthesis reaction Methods 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
- 239000011995 wilkinson's catalyst Substances 0.000 description 1
Images
Classifications
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- D—TEXTILES; PAPER
- D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
- D01F—CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
- D01F9/00—Artificial filaments or the like of other substances; Manufacture thereof; Apparatus specially adapted for the manufacture of carbon filaments
- D01F9/08—Artificial filaments or the like of other substances; Manufacture thereof; Apparatus specially adapted for the manufacture of carbon filaments of inorganic material
- D01F9/10—Artificial filaments or the like of other substances; Manufacture thereof; Apparatus specially adapted for the manufacture of carbon filaments of inorganic material by decomposition of organic substances
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- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- General Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Textile Engineering (AREA)
- Inorganic Fibers (AREA)
Abstract
The invention belongs to the technical field of silicon carbide fiber preparation, and relates to a low-oxygen silicon carbide fiber and a preparation method thereof. The low-oxygen silicon carbide fiber is prepared by taking cyano polycarbosilane as a raw material through the working procedures of spinning, drying, thermosetting and high-temperature sintering, wherein the cyano polycarbosilane is a molecular main chain containing CH 3 SiHCH 2 A compound having a structural unit or a molecular branch containing-C.ident.N. The low-oxygen silicon carbide fiber can be prepared by taking the cyano polycarbosilane as a raw material through the working procedures of spinning, drying, thermosetting and high-temperature sintering, and has the advantages of simple and convenient process, lower cost and the like.
Description
Technical Field
The invention belongs to the technical field of silicon carbide fiber preparation, and relates to a low-oxygen silicon carbide fiber and a preparation method thereof.
Background
Silicon carbide (SiC) fibers are widely applied to the high-technology fields of aerospace, nuclear energy and the like due to excellent high-temperature resistance, oxidation resistance, corrosion resistance and mechanical properties. The precursor conversion method is a main method for preparing SiC fibers at present, and the basic process of the method is mainly divided into the following four steps: synthesis of precursor, spinning, no melting, high temperature sintering and sintering. Air does not melt is a common non-melting method. During this process, a large amount of oxygen is introduced into the fiber (typically above 10%) to form the SiOxCy phase. At the temperature of over 1200 ℃, the SiOxCy phase is heated and decomposed to release CO and SiO gas, which causes damage to the fiber structure and rapid reduction of mechanical properties.
To reduce the oxygen content in SiC fibers, no-melt treatment of Polycarbosilane (PCS) fibrils by electron beam irradiation in an inert atmosphere by Okamura et al (j.am. Center.soc., 1995, 78. The fiber can still maintain the tensile strength of 2.0GPa after being treated in argon gas at 1500 ℃ for 1 h. The technology was developed industrially by carbon corporation of Japan, and in 1995, a novel low oxygen content SiC fiber was produced under the name Hi-Nicalon. However, this method greatly increases the production cost of SiC fibers. The dry spinning method is a method in which a high molecular weight fraction obtained by PCS fractionation is dissolved in an appropriate solvent, and a spinning aid is added to dry-spin the solution into a fiber, and the fiber is directly heat-treated at high temperature without being melt-processed, whereby a SiC fiber having an oxygen content of about 2% can be obtained (composite, sci, technol.,1994, 51-159. However, the fractional precipitation method involved in this technique is complicated and not easily scalable. In addition, methods for reducing the oxygen content of the SiC fibers also comprise a gamma ray irradiation method, a chemical vapor crosslinking method and the like, and the cost is increased undoubtedly. The Chinese patent with the application number of CN201711193380.5 discloses a submicron/nanometer oxygen-free silicon carbide fibrofelt and a preparation method thereof: removing micromolecules from polycarbosilane with the weight average molecular weight of more than 4000 by using a poor solvent to obtain high molecular weight polycarbosilane with the weight average molecular weight of more than 8000, then carrying out electrostatic spinning on spinning solution of the high molecular weight polycarbosilane, a spinning-assistant polymer and an organic solvent, and obtaining the submicron/nanometer silicon carbide fiber felt after heating treatment and high-temperature cracking. The invention patent of China with the application number of CN201810035177.3 synthesizes polycarbosilane with thermal curing property and vinyl-containing silane through hydrosilylation, then obtains polycarbosilane fiber through dry spinning, and obtains low-oxygen content silicon carbide fiber after heat treatment and high-temperature cracking. The processes for preparing the precursors used in these techniques are relatively complex.
Disclosure of Invention
The invention aims to provide a low-oxygen silicon carbide fiber and a preparation method thereof aiming at the defects of the prior art.
The aforementioned object of the present invention is achieved by the following technical solutions:
the low-oxygen silicon carbide fiber is prepared by taking cyano polycarbosilane as a raw material through the processes of spinning, drying, thermosetting and high-temperature sintering.
Preferably, the cyano-containing polycarbosilane contains CH in the molecular main chain 3 SiHCH 2 A compound having a structural unit or a molecular branch containing-C.ident.N.
Preferably, the cyano-containing polycarbosilane has a softening point of greater than 250 ℃ and a weight average molecular weight of greater than 4000g/mol.
Preferably, the cyano-containing polycarbosilane contains heterogeneous elements, and the heterogeneous elements comprise one or more of aluminum, iron, titanium, zirconium, cobalt, nickel, boron, lanthanum, yttrium and niobium. When the cyano group-containing polycarbosilane contains heterogeneous elements, the oxygen content in the silicon carbide fiber can be more effectively reduced by using the cyano group-containing polycarbosilane as a raw material to prepare the silicon carbide fiber. The content of the heterogeneous element in the cyano group-containing polycarbosilane is not limited, and any content of the heterogeneous element is within the protection scope of the present application.
The raw material of the cyano polycarbosilane used in the invention can be prepared by referring to the method of patent CN 109354691.
Preferably, the low-oxygen silicon carbide fiber is not subjected to an air infusibility treatment process.
The air is not melted, namely, the heating treatment is carried out in the air atmosphere, and the air is not melted in the preparation process of the silicon carbide fiber, which is a common procedure. However, a large amount of oxygen is introduced during the air infusible process, resulting in a drastic drop in the performance of the silicon carbide fiber at high temperatures. The method takes the polycarbosilane containing the cyano groups as the raw material, does not need to pass through the air non-melting treatment process, and can prepare the silicon carbide fiber by directly passing through the spinning, drying, thermosetting and high-temperature sintering processes, and the prepared silicon carbide fiber has low oxygen content which is less than 3 percent.
The other purpose of the invention is realized by the following technical scheme:
a preparation method of low-oxygen silicon carbide fiber comprises the following steps: dissolving cyano polycarbosilane in an organic solvent to prepare a spinning solution; spinning the spinning solution to obtain polycarbosilane fiber containing cyano; heating the cyano polycarbosilane fiber in an inert atmosphere, and drying and thermally curing; and (3) carrying out high-temperature firing on the dried and thermally cured fiber in an inert atmosphere to obtain the low-oxygen silicon carbide fiber.
Preferably, the organic solvent is composed of a good solvent and a poor solvent.
Preferably, the good solvent is one or more of toluene, xylene, tetrahydrofuran, n-hexane and chloroform, and the poor solvent is one or more of ethanol, n-propanol, isopropanol, acetone, dimethylformamide and ethyl formate.
Preferably, the mass ratio of the cyano-containing polycarbosilane to the good solvent to the poor solvent is 40-65:30-55:5-25.
Preferably, the spinning is electrostatic spinning or dry spinning.
Preferably, when the spinning is electrostatic spinning, the process conditions of the electrostatic spinning include: the inner diameter of a spinneret orifice is 0.3-2mm, the spinning voltage is 10-25kV, the distance between the spinneret and a filament collector is 10-25cm, and the feeding speed is 10-35 mu L/min.
Preferably, when the spinning is dry spinning, the process conditions of the dry spinning comprise: under the protection of inert atmosphere, the spinning solution is heated to 50-150 ℃ in a spinning device, the temperature is kept for 0.5-5h, and inert gas or a metering pump is used for ejecting the spinning solution through a spinneret orifice to form the cyano-containing polycarbosilane fiber.
Preferably, the dry heat curing conditions include: heating to 250-280 deg.c at 0.5-2 deg.c/min in inert atmosphere, heating to 280-350 deg.c at 0.2-1.0 deg.c/min and maintaining at this temperature for 0.5-2 hr. The invention does not adopt the air not to melt the treatment process, but heats under the inert atmosphere to dry and solidify.
Preferably, the high-temperature firing conditions include: heating to 1000-1800 ℃ at 2-10 ℃/min under inert atmosphere, and preserving heat for 0.5-2h at the temperature.
Inert atmospheres herein include, but are not limited to, argon atmospheres, nitrogen atmospheres.
Compared with the prior art, the invention has the following beneficial effects:
(1) The low-oxygen silicon carbide fiber is prepared by taking cyano polycarbosilane as a raw material through the working procedures of spinning, drying, thermosetting and high-temperature sintering, wherein the oxygen content is less than 3%;
(2) The silicon carbide fiber is dried and thermally cured in inert atmosphere without adopting the air non-melting treatment process, wherein the drying and thermally curing conditions are that the temperature is increased to 250-280 ℃ at the speed of 0.5-2 ℃/min in the inert atmosphere, then the temperature is increased to 280-350 ℃ at the speed of 0.2-1.0 ℃/min, and the temperature is kept for 0.5-2h at the temperature, so that the introduction of a large amount of oxygen is avoided;
(3) When the cyano polycarbosilane contains heterogeneous elements, the cyano polycarbosilane is used as a raw material to prepare the silicon carbide fiber, so that the oxygen content in the silicon carbide fiber can be effectively reduced, and certain functional properties such as wave absorption, electromagnetic shielding and the like are endowed to the silicon carbide fiber;
(4) Compared with the prior art, the preparation method of the low-oxygen silicon carbide fiber has simpler process and lower cost.
Drawings
Fig. 1 (a) and 1 (b) are SEM photographs of the SiC fiber 1 in example 1 of the present invention, fig. 1 (c) is an SEM photograph of the SiC fiber 1 in example 1 of the present invention after being thermostated at 1400 ℃ for 1 hour, and fig. 1 (d) is an SEM photograph of the SiC fiber 1 in example 1 of the present invention after being thermostated at 1600 ℃ for 1 hour.
Detailed Description
The technical solutions of the present invention are further described and illustrated in the following specific embodiments and the accompanying drawings, it should be understood that the specific embodiments described herein are only for the purpose of facilitating understanding of the present invention, and are not intended to limit the present invention specifically. And the drawings used herein are for the purpose of illustrating the disclosure better and are not intended to limit the scope of the invention. The raw materials used in the examples of the present invention are those commonly used in the art, and the methods used in the examples are those conventional in the art, unless otherwise specified.
1. Preparation of cyano-containing polycarbosilane PCS-CN01
50g of Polycarbosilane (PCS) (the softening point is 250 ℃, the weight average molecular weight is 3820 g/mol) is dissolved in 60g of Tetrahydrofuran (THF), the solution is added into a 250ml flask after being completely dissolved, 10g of acrylonitrile is added, 0.003g of Wilkinson catalyst is added under the protection of nitrogen, and then the reaction system is heated to 60 ℃ for reaction for 8h. Finally, THF is removed by distillation under reduced pressure to obtain cyano-containing polycarbosilane PCS-CN01.
The softening point of PCS-CN01 is 255 ℃ and the weight-average molecular weight is 4120g/mol.
Example 1
The preparation method of the silicon carbide fiber of the embodiment is as follows:
taking 5.5g of PCS-CN01 precursor, and respectively adding 3.6g of dimethylbenzene and 0.9g of acetone to prepare spinning solution;
then carrying out electrostatic spinning to obtain PCS-CN01 fiber, wherein the spinning conditions are as follows: the inner diameter of a spinneret orifice is 0.8mm, the spinning voltage is 16kV, the distance between a spinneret and a filament receiver is 15cm, and the feeding speed is 30 mu L/min;
putting the PCS-CN01 fiber into a tube furnace, heating to 250 ℃ at a speed of 2 ℃/min under the protection of argon atmosphere, then heating to 300 ℃ at a speed of 0.5 ℃/min, preserving heat for 1h, and drying and thermally curing;
and (3) putting the dried and thermally cured fiber into a high-temperature furnace, heating to 1200 ℃ at a speed of 2 ℃/min under the protection of argon atmosphere, and preserving heat for 2h at the temperature to obtain the SiC fiber 1.
The SiC fiber 1 was tested to have an oxygen content of 2.2%.
FIGS. 1 (a), (b) are SEM photographs of an SiC fiber 1 in example 1 of the present invention; FIG. 1 (c) is an SEM photograph of the SiC fiber 1 at 1400 ℃ for 1 hour; FIG. 1 (d) is an SEM photograph of the SiC fiber 1 at 1600 ℃ for 1 hour. As can be seen, the SiC fiber 1 has low oxygen content, so that the fiber structure can still be kept complete at the constant temperature of 1600 ℃ for 1h without generating pores.
Example 2
The preparation method of the silicon carbide fiber of the embodiment is as follows:
taking 20g of PCS-CN01 precursor, and adding 10g of dimethylbenzene and 3g of acetone respectively to prepare spinning solution;
then carrying out dry spinning to obtain PCS-CN02 fiber, wherein the dry spinning conditions are as follows: under the protection of argon atmosphere, raising the temperature of the spinning solution in a spinning device to 80 ℃, preserving the temperature for 0.5h, and ejecting the spinning solution through an argon gas through a spinneret orifice, wherein the pressure of the argon gas is 0.3MPa;
putting the PCS-CN02 fiber into a tube furnace, heating to 250 ℃ at a speed of 2 ℃/min under the protection of argon atmosphere, then heating to 300 ℃ at a speed of 0.5 ℃/min, preserving heat for 1h, and drying and thermally curing;
and (3) putting the dried and thermally cured fiber into a high-temperature furnace, heating to 1200 ℃ at a speed of 2 ℃/min under the protection of argon atmosphere, and preserving heat for 2h at the temperature to obtain the SiC fiber 2.
The SiC fiber 2 was tested to have an oxygen content of 2.3%.
2. Preparation of cyano-containing polyaluminum carbosilane PACS-CN01
50g of aluminum-containing Polycarbosilane (PACS) (the softening point is 260 ℃, the weight-average molecular weight is 4130g/mol, the aluminum content is 1 wt%) is dissolved in 60g of Tetrahydrofuran (THF), the solution is added into a 250ml flask after being completely dissolved, 10g of acrylonitrile is added, 0.5g of azodiisobutyronitrile catalyst is added under the protection of nitrogen, and then the reaction system is heated to 60 ℃ for reaction for 15 hours. Finally, THF is removed in a reduced pressure distillation mode to obtain the cyano-containing polyaluminocarbosilane PACS-CN01.
The softening point of PACS-CN01 is 267 ℃ and the weight-average molecular weight is 4250g/mol.
Example 3:
the preparation method of the silicon carbide fiber of the embodiment is as follows:
taking 5.5g of PACS-CN01 precursor, and adding 4g of tetrahydrofuran and 1g of n-propanol respectively to prepare a spinning solution;
then carrying out electrostatic spinning to obtain the PACS-CN01 fiber, wherein the spinning conditions are as follows: the inner diameter of a spinneret orifice is 0.8mm, the spinning voltage is 18kV, the distance between a spinneret and a filament receiver is 15cm, and the feeding speed is 25 mu L/min;
putting the PACS-CN01 fiber into a tube furnace, heating to 260 ℃ at a speed of 2 ℃/min under the protection of argon atmosphere, then heating to 290 ℃ at a speed of 0.5 ℃/min, preserving heat for 1h, and drying and thermally curing;
and (3) putting the dried and thermally cured fiber into a high-temperature furnace, heating to 1800 ℃ at a speed of 2 ℃/min under the protection of argon atmosphere, and preserving heat at the temperature for 1h to obtain the SiC fiber 3.
The SiC fiber 3 was tested to have an oxygen content of 0.5%.
Example 4
The preparation method of the silicon carbide fiber of the embodiment is as follows:
taking 20g of PACS-CN01 precursor, and adding 12g of tetrahydrofuran and 3g of ethanol respectively to prepare a spinning solution;
then, dry spinning is carried out to obtain the PACS-CN02 fiber, and the dry spinning conditions are as follows: under the protection of argon atmosphere, raising the temperature of the spinning solution in a spinning device to 75 ℃, preserving the temperature for 0.5h, and ejecting the spinning solution through an argon gas through a spinneret orifice, wherein the pressure of the argon gas is 0.2MPa;
putting the PACS-CN02 fiber into a tube furnace, heating to 262 ℃ at a speed of 2 ℃/min under the protection of argon atmosphere, then heating to 290 ℃ at a speed of 0.5 ℃/min, preserving heat for 1h, and drying and thermally curing;
and (3) putting the dried and thermally cured fiber into a high-temperature furnace, heating to 1800 ℃ at a speed of 2 ℃/min under the protection of argon atmosphere, and preserving heat at the temperature for 1h to obtain the SiC fiber 4.
The SiC fiber 4 was tested to have an oxygen content of 0.4%.
3. Preparation of poly-iron carbosilane PFCS-CN01 containing cyan
50g of iron-containing Polycarbosilane (PFCS) (softening point 265 ℃, weight average molecular weight 4190g/mol, iron content 0.5 wt%) is dissolved in 60g of Tetrahydrofuran (THF), after complete dissolution, the solution is added into a 250ml flask, 10g of acrylonitrile is added, 0.5g of azobisisobutyronitrile catalyst is added under the protection of nitrogen, and then the reaction system is heated to 60 ℃ for reaction for 20 hours. Finally, THF was removed by distillation under reduced pressure to give a cyano-containing polyferric carbosilane PFCS-CN01.
PFCS-CN01 was tested to have a softening point of 272 ℃ and a weight average molecular weight of 4330g/mol.
Example 5
The preparation method of the silicon carbide fiber of the embodiment is as follows:
taking 5.5g of a PFCS-CN01 precursor, and adding 4.5g of n-hexane and 1.5g of dimethylformamide respectively to prepare a spinning solution;
then carrying out electrostatic spinning to obtain PFCS-CN01 fiber, wherein the spinning conditions are as follows: the inner diameter of a spinneret orifice is 0.8mm, the spinning voltage is 20kV, the distance between a spinneret and a filament receiver is 15cm, and the feeding speed is 20 mu L/min;
putting the PFCS-CN01 fiber into a tube furnace, heating to 265 ℃ at a speed of 2 ℃/min under the protection of argon atmosphere, then heating to 295 ℃ at a speed of 0.5 ℃/min, preserving heat for 1h, and drying and thermosetting;
and (3) putting the dried and thermally cured fiber into a high-temperature furnace, heating to 1600 ℃ at a speed of 2 ℃/min under the protection of argon atmosphere, and preserving heat for 1.5h at the temperature to obtain the SiC fiber 5.
The SiC fiber 5 was tested to have an oxygen content of 1.8%.
Example 6
The preparation method of the silicon carbide fiber of the embodiment is as follows:
taking 20g of a PFCS-CN01 precursor, and adding 14g of n-hexane and 4g of dimethylformamide respectively to prepare a spinning solution;
then carrying out dry spinning to obtain PFCS-CN02 fiber, wherein the dry spinning conditions are as follows: under the protection of argon atmosphere, the spinning solution is heated to 70 ℃ in a spinning device, the temperature is kept for 0.5h, argon gas is sprayed out through a spinneret orifice, and the pressure of the argon gas is 0.3MPa;
putting the PFCS-CN02 fiber into a tube furnace, heating to 265 ℃ at a speed of 2 ℃/min under the protection of argon atmosphere, then heating to 295 ℃ at a speed of 0.5 ℃/min, preserving heat for 1h, and drying and thermosetting;
and (3) putting the dried and thermocured fiber into a high-temperature furnace, heating to 1700 ℃ at the speed of 2 ℃/min under the protection of argon atmosphere, and preserving heat for 1.5 hours at the temperature to obtain the SiC fiber 6.
The SiC fiber 6 was tested to have an oxygen content of 1.1%.
Comparative example 1
The silicon carbide fiber of comparative example 1 was prepared as follows:
5.5g of Polycarbosilane (PCS) (the softening point is 250 ℃, and the weight average molecular weight is 3820 g/mol) is taken, 3.6g of dimethylbenzene and 0.9g of acetone are respectively added to prepare a spinning solution;
then carrying out electrostatic spinning to obtain PCS01 fiber, wherein the spinning conditions are as follows: the inner diameter of a spinneret orifice is 0.8mm, the spinning voltage is 16kV, the distance between a spinneret and a filament receiver is 15cm, and the feeding speed is 30 mu L/min;
putting the PCS01 fiber into a tube furnace, heating to 210 ℃ at the speed of 0.5 ℃/min under the protection of air atmosphere, preserving heat for 8h, drying and not melting with air;
and (3) putting the fiber which is not melted by the air into a high-temperature furnace, heating to 1200 ℃ at a speed of 2 ℃/min under the protection of argon atmosphere, and preserving the heat for 2h at the temperature to obtain the SiC fiber 7.
The SiC fiber 7 was tested to have an oxygen content of 12.5%.
The aspects, embodiments, features of the present invention should be considered in all respects as illustrative and not restrictive, the scope of the invention being defined solely by the claims. Other embodiments, modifications, and uses will be apparent to those skilled in the art without departing from the spirit and scope of the claimed invention.
The use of headings and chapters in this disclosure is not meant to limit the disclosure; each section can apply to any aspect, embodiment, and feature of the disclosure.
Finally, it should be noted that the specific examples described herein are merely illustrative of the invention and do not limit the embodiments of the invention. Those skilled in the art may now make numerous modifications of, supplement, or substitute for the specific embodiments described, all of which are not necessary or desirable to describe herein. While the invention has been described with respect to specific embodiments, it will be appreciated that various changes and modifications may be made without departing from the spirit and scope of the invention, as defined by the appended claims.
Claims (10)
1. The low-oxygen silicon carbide fiber is characterized in that the low-oxygen silicon carbide fiber is prepared by taking polycarbosilane containing cyano groups as a raw material through the working procedures of spinning, drying, thermosetting and high-temperature sintering.
2. The low-oxygen silicon carbide fiber according to claim 1, wherein the cyano group-containing polycarbosilane contains CH in the molecular main chain 3 SiHCH 2 A compound having a structural unit or a molecular branch containing-C.ident.N.
3. The low-oxygen silicon carbide fiber according to claim 1 or 2, wherein the cyano group-containing polycarbosilane has a softening point of more than 250 ℃ and a weight average molecular weight of more than 4000g/mol.
4. The low oxygen silicon carbide fiber of claim 1 wherein the cyano-containing polycarbosilane comprises a foreign element including one or more of aluminum, iron, titanium, zirconium, cobalt, nickel, boron, lanthanum, yttrium, niobium.
5. A method for preparing a low-oxygen silicon carbide fiber according to claim 1, wherein the method comprises the steps of: dissolving cyano polycarbosilane in an organic solvent to prepare a spinning solution; spinning the spinning solution to obtain polycarbosilane fiber containing cyano; heating the cyano polycarbosilane fiber in an inert atmosphere, and drying and thermally curing; and (3) carrying out high-temperature firing on the dried and thermally cured fiber in an inert atmosphere to obtain the low-oxygen silicon carbide fiber.
6. The production method according to claim 5, wherein the organic solvent is composed of a good solvent and a poor solvent; the good solvent is one or more of toluene, xylene, tetrahydrofuran, n-hexane and chloroform, and the poor solvent is one or more of ethanol, n-propanol, isopropanol, acetone, dimethylformamide and ethyl formate.
7. The preparation method according to claim 6, wherein the mass ratio of the cyano-containing polycarbosilane to the good solvent to the poor solvent is 40-65:30-55:5-25.
8. The preparation method according to claim 5, wherein the spinning is electrostatic spinning, and the process conditions of the electrostatic spinning comprise: the inner diameter of a spinneret orifice is 0.3-2mm, the spinning voltage is 10-25kV, the distance between the spinneret and a filament collector is 10-25cm, and the feeding speed is 10-35 mu L/min;
or the spinning is dry spinning, and the process conditions of the dry spinning comprise: under the protection of inert atmosphere, the spinning solution is heated to 50-150 ℃ in a spinning device, the temperature is kept for 0.5-5h, and inert gas or a metering pump is used for ejecting the spinning solution through a spinneret orifice to form the cyano-containing polycarbosilane fiber.
9. The method of claim 5, wherein drying the thermal curing conditions comprises: heating to 250-280 deg.c at 0.5-2 deg.c/min in inert atmosphere, heating to 280-350 deg.c at 0.2-1.0 deg.c/min, and maintaining at this temperature for 0.5-2 hr.
10. The method of claim 5, wherein the high-temperature firing conditions include: heating to 1000-1800 ℃ at 2-10 ℃/min under inert atmosphere, and preserving heat for 0.5-2h at the temperature.
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| US5171722A (en) * | 1991-10-09 | 1992-12-15 | University Of Florida | SiC fibers having low oxygen content and methods of preparation |
| CN108277555A (en) * | 2018-01-15 | 2018-07-13 | 中国科学院宁波材料技术与工程研究所 | Can be thermally cured the preparation method that Polycarbosilane prepares low oxygen content silicon carbide fibre |
| CN109354691A (en) * | 2018-11-14 | 2019-02-19 | 中国科学院宁波材料技术与工程研究所 | A kind of preparation method of high ceramic yield Polycarbosilane |
| CN111364125A (en) * | 2020-03-11 | 2020-07-03 | 中国科学院宁波材料技术与工程研究所 | Preparation method of silicon carbide ceramic fiber |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5171722A (en) * | 1991-10-09 | 1992-12-15 | University Of Florida | SiC fibers having low oxygen content and methods of preparation |
| CN108277555A (en) * | 2018-01-15 | 2018-07-13 | 中国科学院宁波材料技术与工程研究所 | Can be thermally cured the preparation method that Polycarbosilane prepares low oxygen content silicon carbide fibre |
| CN109354691A (en) * | 2018-11-14 | 2019-02-19 | 中国科学院宁波材料技术与工程研究所 | A kind of preparation method of high ceramic yield Polycarbosilane |
| CN111364125A (en) * | 2020-03-11 | 2020-07-03 | 中国科学院宁波材料技术与工程研究所 | Preparation method of silicon carbide ceramic fiber |
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