CN108752038A - It is a kind of with can be thermally cured Polycarbosilane preparation foam silicon carbide ceramics - Google Patents
It is a kind of with can be thermally cured Polycarbosilane preparation foam silicon carbide ceramics Download PDFInfo
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- C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
- C04B35/515—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on non-oxide ceramics
- C04B35/56—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on non-oxide ceramics based on carbides or oxycarbides
- C04B35/565—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on non-oxide ceramics based on carbides or oxycarbides based on silicon carbide
- C04B35/571—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on non-oxide ceramics based on carbides or oxycarbides based on silicon carbide obtained from Si-containing polymer precursors or organosilicon monomers
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- C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
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Abstract
The invention discloses a kind of can be thermally cured the foam silicon carbide ceramics of Polycarbosilane preparation, this method is by Polycarbosilane and containing the silane of vinyl, pass through hydrosilylation, the Polycarbosilane with heat curable properties is synthesized, then using organic foam as template, dipping obtains the organic foam precast body containing heat cure property Polycarbosilane, the foam preform is heat-treated again, the crosslinking curing for realizing the removing and Polycarbosilane of solvent, finally carries out high temperature pyrolysis, obtains foam silicon carbide ceramics.The preparation, method is simple, and cost is relatively low, and the SiC foam ceramics linear shrinkage ratio prepared is less than 3%, the small 0.6g/cm of bulk density3, between 75%~91%, flexural strength can use open pore rate up to 2.0~2.5MPa in 1100 DEG C of long-times.
Description
Technical field
The invention belongs to ceramic foam technical fields, and in particular to a kind of can be thermally cured the silicon carbide of Polycarbosilane preparation
Foamed ceramics.
Background technology
Foam silicon carbide ceramics have good characteristic：Adaptability is good, anti-oxidant, corrosion-resistant, coefficient of thermal expansion is low, thermostabilization
Property is good, pyroconductivity is low, permeability is high, fluid absorption is good, selective penetrated property is high, energy absorption or damping are good, Yi Jiying
The small equal excellent properties of power load deformation.It is widely used in the necks such as filtering, bioceramic, sound-absorbing, catalyst carrier and chemical filler
Domain.In recent years, the demand with people to foamed ceramics was growing, and preparing high-performance foam ceramics also becomes the task of top priority.
Since SiC is a kind of strong covalent bond compound, self-diffusion coefficient is very small, and direct sintering temperature connects 2000 DEG C, leads to
All be addition sintering aid in the case of often reduce its sintering temperature (She Jihong, the development of the bright silicon carbide ceramics in the east of a river with answer
With ceramic engineerings, 1998,32 (3)：3-11).
In numerous preparation methods, Foam dipping method has a clear superiority：It is fine by organic foam unique three
The slurry prepared is uniformly coated in organic foam mesh skeleton structure and forms foam preform by open mesh skeleton,
Drying process keeps the slurry on foam framework muscle more secured, then burns up Organic Foam Material without pressure, and it is similar to obtain a kind of structure
The foamed ceramics of foaming structure.The technological operation is simple, is readily produced, and the ceramics that stomata connectivity is good and porosity is high can be made
Product.
(Yao Xiumin, Huang Zhengren, Tan Shou flood Polycarbosilane low-temperature sintering silicon carbide nets in traditional Foam dipping method
Development [J] Journal of Inorganic Materials of eye porous ceramics, 2010,25 (02)：168-172.；Liu Wei, Liyang, Chen Lu Polycarbosilanes
Low temperature preparation foam silicon carbide ceramics [J] silicate journals, 2011,39 (11)：1763-1767.；Chen Lu, Liyang, Liu Wei are poly-
Preparation [J] modern mechanicals of carbon silane low-temperature sintering foam silicon carbide ceramics, 2011 (06)：60-61+87.；Sun Wen flies low temperature
Prepare foam silicon carbide ceramics and its performance study [D] Guizhou University, 2017.), mostly use based on Silicon Carbide Powder
Ingredient and binder and solvent is wanted to prepare slurry, using organic foam as template, dipping obtains precast body, is finally sintered precast body and obtains
To foam silicon carbide ceramics.After the addition of sintering aid, sintering prepares SiC foam ceramics temperature mostly at 1400 DEG C or more.Beam
(Liang Hanqin, Yao Xiumin, Huang Zhengren, Liu Xue build liquid phase generating process [J] mechanic when silicon carbide ceramics liquid-phase sinterings to Chinese qin
Journey material, 2015,39 (02)：34-37.) SiC foam ceramic sintering temperature and sintering mechanism are studied, SiC foam
Ceramics are mainly that glass is generated with respect to the cladding of SiC particulate, connection function and cenotype mullite.Liu Wei (Liu Wei, Liyang, Chen Lu
Ceramic [J] the silicate journals of Polycarbosilane low temperature preparation foam silicon carbide ceramics, 2011,39 (11)：1763-1767.) use
Organic formwork infusion process cracks bonding SiC micro mists with Polycarbosilane in 1000 DEG C and is prepared for SiC foams pottery in an inert atmosphere
Porcelain, foamed ceramics linear shrinkage ratio is larger, and flexural strength is increased with the increase of solid concentration, with the increasing of the content of Polycarbosilane
Add first to increase reduces again：Solid concentration is 69.6%, and when Polycarbosilane content is 10%, bending strength is up to 3.9MPa.Liu Jian
(Liu Jian, Xu Yunshu, Xiong Liangping, Xu Guangliang the low pressure molding of SiC powder containing presoma low-temperature sintering SiC porous ceramics [J] China
Powder technology, 2009,15 (03)：Polycarbosilane and SiC powder 28-30.) is used to be prepared for raw material low pressure molding low-temperature sintering
SiC porous ceramics has studied influence of the Polycarbosilane content to SiC porous ceramics performances.Sem analysis shows that Polycarbosilane is split
It solves product to bond by SiC particulate, porous ceramics has interconnected open-celled structure.
In conclusion in traditional Foam dipping method, slurry mainly with Silicon Carbide Powder particle be mainly at
Point, in sintering process, binder forms connection between Silicon Carbide Powder particle, has certain mechanical property to be formed
The ceramic foam of energy.Binder can be divided into：Electrodeless metal oxide and organic compound Polycarbosilane, the former is to foamed ceramics
Element composition has larger impact, and sintering preparation temperature is high, at 1300 DEG C or more；The latter can foam in sintering process, and content is low
When, bond effect unobvious, when content is high, the holding of intensity and hole to foam adversely affects, and foamed ceramics line is received
Shrinkage is larger.In preparing slurry process, no matter the dispersion between that binder and silicon carbide powder is problem, cannot be very
The slurry of stable homogeneous is formed well, this has detrimental effect to the performance of final foamed ceramics.
Therefore, in 105272266 A of patent CN, Li Siwei only uses Polycarbosilane as the precursor of foamed ceramics, with
Solvent xylene prepares slurry, using processed polyurethane foam as template, hanging product is made, first passes through in convection oven
Reason, then foam silicon carbide ceramics are sintered to obtain in high temperature furnace.But in the processing procedure in convection oven, especially for big
Size, when the larger hanging product of volume is handled, oxidation homogeneity is similarly difficult to ensure：It will appear local too high oxygen level；Very
Polycarbosilane to internal layer is not fully developed crosslinking curing, in sintering process, can cause the change of foam caved in hole
Shape.The key point that limitation polymer-derived method prepares foam silicon carbide ceramics is the crosslinking curing process of Polycarbosilane.
Invention content
Present situation in view of the above technology, the present invention is directed to a kind of foam silicon carbide ceramics that prepare of low-cost high-efficiency, exploitations
Going out itself has the Polycarbosilane of heat cure property, no longer needs to carry out during precursor method prepares foam silicon carbide ceramics
Cure treatment.With the precursor that the Polycarbosilane with heat curable properties is unique foam silicon carbide ceramics, it is with dimethylbenzene
Solvent prepares dipping solution, using organic foam as template, prepares the foam preform containing heat curable properties Polycarbosilane, passes through
Further high-temperature process, complete solvent removing and Polycarbosilane it is self-curing, it is no longer necessary to air does not melt technique, simultaneously
Ensure do not occur phenomena such as ceramics itself foam, flow, caving in into silicon carbide ceramics transition process in Polycarbosilane, ensure that
The hole and structural property of foam silicon carbide ceramics, this technique preparation flow is simple, sufficient raw, has prodigious reality
Application value.
In order to achieve the above technical purposes, as shown in Figure 1, the present invention is with Polycarbosilane (PCS) and containing the silane of vinyl
Reaction, makes vinyl group be introduced into PCS structures, obtains the novel Polycarbosilane (PVCS) containing vinyl.Due to the PVCS
Structure in contain two kinds of active groups of-C=C- and Si-H, to assign its own thermally cross-linkable characteristic.That is, the PVCS has
There is heat cure property.Then, dipping solution is prepared, is impregnated by template of organic foam.Then, dipping is obtained organic
Foam preform is heat-treated, and the removing of the self-crosslinking solidification and solvent of Polycarbosilane is completed.Finally to the bubble after solidification
Foam precast body is sintered, and silicon foams decompose completely in the process, noresidue, and the Polycarbosilane after solidification will not occur
Foaming and serious volume contraction obtain the SiC foam ceramics of function admirable to control the pore structure and intensity of foam.
That is, the technical scheme is that：One kind preparing foam silicon carbide ceramics can be thermally cured Polycarbosilane, the carbonization
Preparing for silicon foam ceramics is as follows：
(1) it is made in structure comprising-C=C- and Si-H with containing the silane reaction of vinyl with Polycarbosilane (PCS)
Active group, and it is dissolvable in water the Polycarbosilane (PVCS) of organic solvent；
(2) PVCS is dissolved to obtain dipping solution, completes to impregnate using organic foam as template；
(3) foam preform is heat-treated in an inert atmosphere, realizes removing and the heat cure Polycarbosilane of solvent
Self-crosslinking solidification；
(4) foam preform of crosslinking curing obtains SiC foam ceramics through high temperature pyrolysis.
The PCS is to reset the Polycarbosilane synthesized by polydimethylsiloxane cracking, and softening point is 200~240
DEG C, number-average molecular weight is 1600~1950.
Preferably, being free of Cl elements in the silane containing vinyl.
Preferably, containing multiple vinyl in the silane containing vinyl, such as contain 4-C=C- bases
Group.
Preferably, in the silane containing vinyl, on silicon atom other than connecting vinyl group, it is also connected with it
The saturated alkanes such as his organic group, such as connection methyl, ethyl or propyl.
The silane containing vinyl is unlimited, including tetravinyl cyclotetrasiloxane, three (isoolefine propoxyl group) ethylene
Base silane.
In the step (1), as a kind of realization method, detailed process is as follows：
The Polycarbosilane that mass ratio is 1: 0.1~1 is placed in the silane containing vinyl in reaction vessel, is added first
Organic solvent is uniformly miscible, adds Si-H addition reaction catalysts, after vacuumizing displacement high-purity argon gas, is protected in high-purity argon gas
Under, heating in atmospheric conditions carries out Si-H addition reactions, and the first organic solvent and unreacted silicon are removed after being cooled to room temperature
Hydride compounds obtain product PVCS.
First organic solvent is unlimited, and first organic solvent includes one kind in dimethylbenzene, toluene, acetone
Or it is a variety of.Preferably, the volume mass ratio of first organic solvent and presoma is 5ml/g~50ml/g；
Preferably, the mass ratio of the Polycarbosilane and the silane containing vinyl is 1: (0.1~0.9)；
The Si-H addition reaction catalysts include chloroplatinic acid；
Preferably, the volume mass ratio of the Si-H addition reaction catalysts and presoma is 10ppm~400ppm；
Preferably, react under normal pressure, it is heated to 90~150 DEG C under high-purity argon gas protection, and insulation reaction 6h~
Stop reaction after 30h, reaction mixture is placed in rotary evaporator, 60~100 DEG C are evaporated under reduced pressure out solvent and unreacted silane
Compound obtains PVCS.
In the step (1), the computational methods of Si-H addition reaction degree are：Measure before reaction with react after mixture
Infrared spectrum finds out 2100cm on each comfortable infrared spectrum respectively-1(Si-H) and 1250cm-1(Si-CH3) at characteristic absorption peak
The ratio between absorbance ISiH/ISiH4, that is, (I before reactingSiH/ISiH4) with react after (ISiH/ISiH4), Si-H reaction intervals are found out as the following formula
Degree, PSiH：
In the step (2), as a kind of realization method, detailed process is as follows：It is mixed with PVCS and the second organic solvent
It is made into slurry, using organic foam as template, dipping arrives organic foam precast body
Preferably, the solution concentration is 30~80%wt；
Preferably, the vacuum degree is 0.1Pa~1Pa；
Preferably, the organic foam is unlimited, including polyurethane foam, polystyrene foam etc.；
Second organic solvent is one or more in tetrahydrofuran, acetone, n-hexane, toluene and dimethylbenzene.
In the step (3), as a kind of realization method, detailed process is as follows：In an inert atmosphere by organic foam, with
The heating rate of 1 DEG C/min~15 DEG C/min is warming up to 200 DEG C~400 DEG C, keeps the temperature 1h~8h.
In the step (4), as a kind of realization method, detailed process is as follows：By step (3), treated, and precast body exists
Under inert atmosphere, with the heating rate of 5 DEG C/min~50 DEG C/min, 1000 DEG C~1200 DEG C are heated to, heat preservation 0.5h~3h is small
When, it then cools to room temperature.Obtain foam silicon carbide ceramics.
Preferably, the bulk density 0.5g/cm of the SiC foam ceramics3, open pore rate between 80%~91% it
Between, flexural strength reaches 2.3MPa.
One kind preparing foam silicon carbide ceramics can be thermally cured Polycarbosilane, is made using the above method.
(1) present invention makes vinyl group be introduced into PCS structures with Polycarbosilane (PCS) with containing the silane reaction of vinyl
In, obtain the novel Polycarbosilane with heat cure property.Then, dipping solution is prepared, is soaked by template of organic foam
Stain.Then, the organic foam precast body obtained to dipping is heat-treated, and completes the removing of solvent and itself handing over for Polycarbosilane
Connection solidification.Finally the foam preform after solidification is pyrolyzed, silicon foams decompose completely in the process, noresidue,
Foaming will not occur for the Polycarbosilane after solidification and serious volume contraction obtains to control the pore structure and intensity of foam
To the SiC foam ceramics of function admirable.Bulk density < 06g/cm3, open pore rate is between 80%~91%, flexural strength
Up to 2.0MPa or more.
(2) present invention improves polymer-derived method and prepares foam silicon carbide ceramics, and the sic foam homogeneity of preparation is stablized, no
Air not melting process is needed, valuable scheme is provided to prepare large scale foamed ceramics for polymer-derived method.
(3) present invention is impregnated using solution, and in the foam preform of preparation, Polycarbosilane is uniform, dipping effect higher.
Description of the drawings
Fig. 1 is the preparation flow schematic diagram of foam silicon carbide ceramics of the present invention.
Specific implementation mode
With reference to embodiment, present invention is further described in detail, it should be pointed out that embodiment described below purport
Convenient for the understanding of the present invention, and any restriction effect is not played to it.
Embodiment 1：
With can be thermally cured Polycarbosilane prepare foam silicon carbide ceramics preparation process it is as follows：
(1) preparation of PVCS
The Polycarbosilane synthesized is reset by polydimethylsiloxane cracking, softening point is 230 DEG C, and number-average molecular weight is
1750。
The PCS and tetravinyl cyclotetrasiloxane are added by 1: 0.3 mass ratio in reaction kettle, by dimethylbenzene/PCS
It is added that dimethylbenzene is uniformly miscible for the ratio of 10ml/g, then chloroplatinic acid is added as urging using the ratio that chloroplatinic acid/PCS is 100ppm
Agent after vacuumizing displacement high-purity argon gas, is then heated to 120 DEG C, stops reaction after insulation reaction 20h, incited somebody to action after being cooled to room temperature
Reaction mixture is placed in distilling apparatus, under high-purity argon gas protection, is warming up to 80 DEG C, is evaporated under reduced pressure out solvent and unreacted silane
Compound obtains product PVCS.
The silicon hydrogen extent of reaction that PCS is obtained using the computational methods of the Si-H addition reaction degree is 18%.Product
PVCS both contains vinyl, also contains Si-H, and dissolubility is excellent.
(2) dipping obtains organic foam precast body
With PVCS obtained above and dimethylbenzene mixing wiring solution-forming, viscosity 20Pas；Using organic foam as template,
Pressure is 0.5Pa, is impregnated, and after dipping, squeezes out redundant solution and obtains organic foam precast body.
(3) it is heat-treated organic foam precast body
Organic foam precast body is put into stove, after vacuumizing displacement high-purity argon gas three times, by organic foam in high-purity argon
In gas, 220 DEG C are warming up to the heating rate of 10 DEG C/min, keeps the temperature 1h.
(4) pyrolysis prepares foam silicon carbide ceramics
In argon gas atmosphere, by step (3) treated precast body with the heating rate of 5 DEG C/min, it is heated to 1100
DEG C, 1h hours are kept the temperature, then cools to room temperature, obtains black bright foam silicon carbide ceramics.Bulk density 0.5g/cm3, open gas
Between porosity 83%, flexural strength reaches 2.3MPa.
Using EMGA-620W model oxygen-nitrogen analyzers, the oxygen content for measuring foam silicon carbide ceramics obtained above is
8.6wt%.
Embodiment 2：
With can be thermally cured Polycarbosilane prepare foam silicon carbide ceramics preparation process it is as follows：
The Polycarbosilane synthesized is reset by polydimethylsiloxane cracking, softening point is 220 DEG C, and number-average molecular weight is
1700。
The PCS and three (isoolefine propoxyl group) vinyl silanes are added by 1: 0.5 mass ratio in reaction kettle, by diformazan
The ratio addition dimethylbenzene that benzene/PCS is 15ml/g is uniformly miscible, then chlorine platinum is added with the ratio that chloroplatinic acid/PCS is 100ppm
Acid is used as catalyst, vacuumizes, and after replacing high-purity argon gas three times, is then heated to 120 DEG C, stops reaction after insulation reaction 20h,
Reaction mixture is placed in distilling apparatus after being cooled to room temperature, under high-purity argon gas protection, 80 DEG C is warming up to, is evaporated under reduced pressure out solvent
And unreacted silicon hydride compounds, obtain product PVCS.
The silicon hydrogen extent of reaction that PCS is obtained using the computational methods of the Si-H addition reaction degree is 15%, product
PVCS both contains vinyl, also contains Si-H, and dissolubility is excellent.
(2) dipping obtains organic foam precast body
With PVCS obtained above and dimethylbenzene mixing wiring solution-forming, viscosity 30Pas；Using organic foam as template,
It completes to impregnate under 0.1Pa pressure, after dipping, squeezes out redundant solution and obtain organic foam precast body.
(3) it is heat-treated organic foam precast body
Organic foam precast body is put into stove, is vacuumized, after replacing high-purity argon gas three times three times, by organic foam in height
In pure argon atmosphere, 200 DEG C are warming up to the heating rate of 10 DEG C/min, keeps the temperature 3h.
(4) pyrolysis prepares foam silicon carbide ceramics
In high-purity argon gas atmosphere, by step (3), treated that organic foam precast body is warming up to 1000 with 10 DEG C/min
DEG C, 5h is kept the temperature, then cools to room temperature, obtains black bright foam silicon carbide ceramics.Bulk density 0.4g/cm3, open pore
Between rate 84%, flexural strength reaches 2.1MPa.
Using EMGA-620W model oxygen-nitrogen analyzers, the oxygen content for measuring foam silicon carbide ceramics obtained above is
6.1wt%.
Embodiment 3：
With can be thermally cured Polycarbosilane prepare foam silicon carbide ceramics preparation process it is as follows：
The preparation of step (1) PVCS is the same as embodiment 1
(2) dipping obtains organic foam precast body
With PVCS obtained above and dimethylbenzene mixing wiring solution-forming, viscosity 40Pas；Using organic foam as template,
Organic foam precast body is obtained after dipping.
Step (3) and (four) are the same as embodiment 2
Obtain black bright foam silicon carbide ceramics.Bulk density 0.5g/cm3, between open pore rate 84%, flexural strength
Up to 2.3MPa.
Using EMGA-620W model oxygen-nitrogen analyzers, the oxygen content for measuring foam silicon carbide ceramics obtained above is
7.5wt%.
Technical scheme of the present invention is described in detail in embodiment described above, it should be understood that the above is only
For specific embodiments of the present invention, it is not intended to restrict the invention, all any modifications made in the spirit of the present invention,
Supplement or similar fashion replacement etc., should all be included in the protection scope of the present invention.
Claims (10)
1. a kind of can be thermally cured the foam silicon carbide ceramics of Polycarbosilane preparation, the foam silicon carbide ceramics pass through following step
Suddenly it is prepared：
(1) it is made comprising-C=C- and Si-H active groups in structure with containing the silane reaction of vinyl with Polycarbosilane, and
And be dissolvable in water organic solvent can be thermally cured Polycarbosilane, can be thermally cured Polycarbosilane as presoma；
(2) Polycarbosilane dissolving will be can be thermally cured and prepares dipping solution, and using organic foam as template, completed the dipping of foam, obtain
To the organic foam precast body containing dipping solution；
(3) organic foam precast body is heat-treated in an inert atmosphere, realizes the friendship of solvent removal and Polycarbosilane itself
Connection solidification；
(4) high temperature pyrolysis is carried out to the organic foam after crosslinking curing, obtains foam silicon carbide ceramics.
2. as described in claim 1 can be thermally cured the foam silicon carbide ceramics of Polycarbosilane preparation, it is characterized in that：Described
Polycarbosilane is to be reset synthesize by polydimethylsiloxane cracking, and softening point is 200~240 DEG C, number-average molecular weight for 1600~
1950。
3. as claimed in claim 1 or 2 can be thermally cured the foam silicon carbide ceramics of Polycarbosilane preparation, it is characterized in that：Institute
The silane containing vinyl stated includes in both tetravinyl cyclotetrasiloxane and three (isoolefine propoxyl group) vinyl silanes
It is at least one.
4. as claimed in claim 1,2 or 3 prepare foam silicon carbide ceramics can be thermally cured Polycarbosilane, it is characterized in that：Institute
It states in step (1), detailed process is as follows：
The Polycarbosilane that mass ratio is 1: 0.1~1 is placed in the silane containing vinyl in reaction vessel, it is organic to be added first
Solvent is uniformly miscible, adds Si-H addition reaction catalysts, after vacuumizing displacement high-purity argon gas, under high-purity argon gas protection,
In atmospheric conditions, heating carries out Si-H addition reactions, and the first organic solvent and unreacted silane are removed after being cooled to room temperature
Compound is contained the Polycarbosilane of-C=C- and Si-H active groups.
5. as described in any one of claim 1-4 with can be thermally cured Polycarbosilane preparation foam silicon carbide ceramics,
It is characterized in：First organic solvent includes one or more in dimethylbenzene, toluene, acetone；
Preferably, the volume mass ratio of first organic solvent and presoma is 5ml/g~50ml/g；
Preferably, the mass ratio of the presoma and the silane containing vinyl is 1: (0.1~0.9)；
The Si-H addition reaction catalysts include chloroplatinic acid；
Preferably, the volume mass ratio of the Si-H addition reaction catalysts and presoma is 10ppm~400ppm；
Preferably, reacting under normal pressure, 90~150 DEG C are heated under high-purity argon gas protection, and after insulation reaction 6h~30h
Stop reaction, reaction mixture is placed in rotary evaporator, 60~100 DEG C are evaporated under reduced pressure out solvent and the conjunction of unreacted silicon alkanisation
Object is contained the Polycarbosilane of-C=C- and Si-H active groups.
6. as described in any one of claim 1-5 with can be thermally cured Polycarbosilane preparation foam silicon carbide ceramics,
It is characterized in：In the step (2), detailed process is as follows：
With containing vinyl Polycarbosilane and the second organic solvent mixing be made into dipping solution, complete organic bubble under vacuum
The dipping of foam obtains the organic foam precast body containing solution.
7. as described in any one of claim 1-6 with can be thermally cured Polycarbosilane preparation foam silicon carbide ceramics,
It is characterized in：A concentration of 30~80%wt of the dipping solution；
Preferably, the vacuum degree is 0.1Pa~1Pa；
Preferably, the organic foam is polyurethane foam；
Second organic solvent is one or more in tetrahydrofuran, acetone, n-hexane, toluene and dimethylbenzene.
8. as described in any one of claim 1-7 with can be thermally cured Polycarbosilane preparation foam silicon carbide ceramics,
It is characterized in：In the step (3), detailed process is as follows：
In an inert atmosphere by organic foam, 200 DEG C~400 DEG C are warming up to the heating rate of 1 DEG C/min~15 DEG C/min, protected
Warm 1h~8h；Si―H addition reaction occurs for two kinds of active groups of-C=C- and Si-H in heat cure Polycarbosilane, completes intermolecular
There is " crosslinking curing of Polycarbosilane itself " that is, in step 3 in crosslinking.
9. as described in any one of claim 1-8 with can be thermally cured Polycarbosilane preparation foam silicon carbide ceramics,
It is characterized in：In the step (4), detailed process is as follows：
Under an inert atmosphere by step (3) treated foam preform, with the heating rate of 5 DEG C/min~50 DEG C/min, add
Heat keeps the temperature 0.5h~3h hours, then cools to room temperature to 1000 DEG C~1200 DEG C；Polycarbosilane after crosslinking curing occurs to divide
Solution deviates from organic molecule, obtains silicon carbide ceramics.
10. as described in any one of claim 1-9 with can be thermally cured Polycarbosilane preparation foam silicon carbide ceramics,
It is characterized in：The oxygen content of foam silicon carbide ceramics obtained is in 5~10wt%；
Preferably, the bulk density 0.5g/cm of foam silicon carbide ceramics obtained3, open pore rate between 80%~91% it
Between, flexural strength reaches 2.3MPa.
Preferably, in an inert atmosphere, 1100 DEG C, after 100h, flexural strength retention rate is 90% or more.
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| CN111925386A (en) * | 2020-09-24 | 2020-11-13 | 长沙科航特种织造有限公司 | Preparation method of novel silicon carbide ceramic precursor |
| CN112126065A (en) * | 2020-09-24 | 2020-12-25 | 长沙科航特种织造有限公司 | Preparation method of solid silicon carbide ceramic precursor |
| CN113896539A (en) * | 2021-11-02 | 2022-01-07 | 航天材料及工艺研究所 | High-temperature-resistant oxidation-resistant light heat-insulating foam material and preparation method thereof |
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| CN113896539A (en) * | 2021-11-02 | 2022-01-07 | 航天材料及工艺研究所 | High-temperature-resistant oxidation-resistant light heat-insulating foam material and preparation method thereof |
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Application publication date: 20181106 |