CN101215184A - Method for preparing foam silicon nitride ceramics - Google Patents
Method for preparing foam silicon nitride ceramics Download PDFInfo
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- CN101215184A CN101215184A CNA200710144954XA CN200710144954A CN101215184A CN 101215184 A CN101215184 A CN 101215184A CN A200710144954X A CNA200710144954X A CN A200710144954XA CN 200710144954 A CN200710144954 A CN 200710144954A CN 101215184 A CN101215184 A CN 101215184A
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Abstract
A process for preparing foaming silicon nitride ceramics relates to a process for preparing silicon nitride ceramics, which resolves the problems in the prior art that the process for preparing foaming silicon nitride ceramics is complex, the cost is high, the material compression intensity is low, heat conductivity is high and large-scale controlling porosity is difficult. The preparing method is that mixing silicon nitride suspending liquid and gelling agent, still mixing the mixture and coal ash hollow micro-beads. Injection molding the obtained suspending binding liquid, sintering the billet which is frozen, demolded and dried with room temperature under protective atmosphere to obtain foaming silicon nitride ceramics. The invention uses coal ash hollow micro-beads as raw materials of pore-forming agent and combustion improver, thereby the cost is low, the process is simple, the coal ash hollow micro-beads can reduce the heat conductivity of the material, the heat resistance is good, the material compression intensity is strengthened and the large-scale controlling porosity is capable.
Description
Technical field
The present invention relates to a kind of preparation method of silicon nitride ceramics.
Background technology
Foamed ceramics has high surface-area, high impregnability, low density, low thermal capacitance, low thermal conduction and excellent high-temperature behavior.Compare with organic foam material, ceramic foam material has high intensity, high hardness, high-temperature capability, high anti-environmental corrosion ability; Compare with metal foaming material, ceramic foam material has low density, high oxidation-resistance, low thermal conduction, low thermal expansivity and high-temperature capability.
Foamed ceramics is widely used because special geometric construction and performance, as is used for the strainer, support of the catalyst, biomaterial, gas burner of lagging material, molten metal and the hot gas of body of heater and aviation or as light material.
Foamed ceramics can adopt foaming method to make, but it is bigger to be only applicable to prepare pore, the foamed ceramics that void content is high, and its void content scope is narrower generally 85～90%, and the material compressive strength is 8～15MPa.Also can be by adopting sponge or other polymer materials as template, prepare by clone method, but also to be warmed up to 300～800 ℃ of slow cracking after the moulding with the speed of 0.5～1 ℃/min and come the burn off template, complex process, cost height, cause the material structure defective easily, and the material compressive strength is low, only is 5～8MPa.
Summary of the invention
The present invention seeks to for solve foam silicon nitride ceramics complicated process of preparation in the prior art, cost height, the material compressive strength is low, thermal conductivity is high, and is difficult to control the problem of void content on a large scale, and provides a kind of preparation method of foam silicon nitride ceramics.
Preparing a kind of foam silicon nitride ceramics realizes according to the following steps: one, by volume per-cent mixes 5～8h with the water for ball milling of 30%～42% silicon nitride and 58%～70%, silicon nitride suspending liquid; Two, by volume per-cent mixes the gelifying agent of 85%～90% silicon nitride suspending liquid and 10%～15% down at 55～60 ℃ and stirs, mixed solution; Three, by volume per-cent mixes the coal fly ash hollow micro bead of 35%～65% mixed solution and 35%～65%, stirs 20～30min, viscosity be the suspension mucus of 0.5～1Pas; Four, suspension mucus is injected mould, at room temperature solidifies the demoulding behind dry 1～2h, then at room temperature ventilation drying 24～36h, dry back base substrate; Five, base substrate after the drying is put into atmosphere sintering furnace, fill shielding gas, under 0.1～0.3MPa pressure, be warmed up to 1500～1700 ℃ with 10～20 ℃ speed, sintering 1～2h promptly gets foam silicon nitride ceramics.
It is that pore-forming material and sintering agent prepare foam silicon nitride ceramics that the present invention adopts coal fly ash hollow micro bead, and raw materials cost is cheap, and technology is simple; Coal fly ash hollow micro bead can also impel the decline of material thermal conductivity, and resistance toheat is good; By the adding of coal fly ash hollow micro bead, can obtain the foam silicon nitride ceramics that compressive strength is 77.2MPa; The adding of coal fly ash hollow micro bead can be controlled void content on a large scale, and void content is 50～75%.
Embodiment
Embodiment one: present embodiment prepares a kind of foam silicon nitride ceramics and realizes according to the following steps:
One, by volume per-cent mixes 5～8h with the water for ball milling of 30%～42% silicon nitride and 58%～70%, silicon nitride suspending liquid; Two, by volume per-cent mixes the gelifying agent of 85%～90% silicon nitride suspending liquid and 10%～15% down at 55～60 ℃ and stirs, mixed solution; Three, by volume per-cent mixes the coal fly ash hollow micro bead of 35%～65% mixed solution and 35%～65%, stirs 20～30min, viscosity be the suspension mucus of 0.5～1Pas; Four, suspension mucus is injected mould, at room temperature solidifies the demoulding behind dry 1～2h, then at room temperature ventilation drying 24～36h, dry back base substrate; Five, base substrate after the drying is put into atmosphere sintering furnace, fill shielding gas, under 0.1～0.3MPa pressure, be warmed up to 1500～1700 ℃ with 10～20 ℃ speed, sintering 1～2h promptly gets foam silicon nitride ceramics.
Embodiment two: present embodiment and embodiment one are different is that the purity of used silicon nitride raw material in the step 1 is 95～99%.Other step and parameter are identical with embodiment one.
Embodiment three: present embodiment and embodiment one are different be in the step 1 by volume per-cent 40% silicon nitride and 60% water for ball milling are mixed 6h.Other step and parameter are identical with embodiment one.
Embodiment four: present embodiment and embodiment one are different be in the step 2 by volume hundred parts of ratios the gelifying agent of 87% silicon nitride suspending liquid and 13% mixed down at 58 ℃ stir.Other step and parameter are identical with embodiment one.
Embodiment five: present embodiment and embodiment one are different is that gelifying agent in the step 2 is the agarose solution of mass concentration 2～3% or the aqueous agar solution of mass concentration 2～5%.Other step and parameter are identical with embodiment one.
Embodiment six: present embodiment and embodiment one are different be in the step 3 by volume per-cent 50% mixed solution and 50% coal fly ash hollow micro bead are mixed, stir 25min, viscosity be the suspension mucus of 0.8Pas.Other step and parameter are identical with embodiment one.
Embodiment seven: present embodiment and embodiment one are different is that the particle diameter of used coal fly ash hollow micro bead ball in the step 3 is 40～200 μ m.Other step and parameter are identical with embodiment one.
Embodiment eight: present embodiment and embodiment one are different is that the particle diameter of used coal fly ash hollow micro bead ball in the step 3 is 100 μ m.Other step and parameter are identical with embodiment one.
Embodiment nine: present embodiment and embodiment one are different is to solidify the demoulding, the dry 25h in the room temperature ventilation then behind the dry 1.5h in the step 4.Other step and parameter are identical with embodiment one.
Embodiment ten: what present embodiment and embodiment one were different is that shielding gas is argon gas or nitrogen in the step 5.Other step and parameter are identical with embodiment one.
Embodiment 11: present embodiment and embodiment one are different be in the step 5 under 0.2MPa pressure, be warmed up to 1600 ℃ with 15 ℃ speed, sintering 1.5h.Other step and parameter are identical with embodiment one.
Embodiment 12: present embodiment prepares a kind of foam silicon nitride ceramics and realizes according to the following steps: one, by volume per-cent mixes 6h with the water for ball milling of 42% silicon nitride and 58%, silicon nitride suspending liquid; Two, by volume per-cent mixes the gelifying agent of 87% silicon nitride suspending liquid and 13% down at 58 ℃ and stirs, mixed solution; Three, by volume per-cent mixes the coal fly ash hollow micro bead of 50% mixed solution and 50%, stirs 25min, viscosity be the suspension mucus of 0.8Pas; Four, suspension mucus is injected mould, at room temperature solidifies the demoulding behind the dry 1.5h, the dry 24h in the room temperature ventilation then, dry back base substrate; Five, base substrate after the drying is put into atmosphere sintering furnace, fill shielding gas, under 0.2MPa pressure, be warmed up to 1500 ℃ with 15 ℃ speed, sintering 1h promptly gets foam silicon nitride ceramics a, and the foam silicon nitride ceramics b of a and prior art for preparing is done the thermal conductivity contrast; The result is as shown in table 1, adopts coal fly ash hollow micro bead to do the foam silicon nitride ceramics of pore-forming material and sintering agent preparation among the present invention, and thermal conductivity is low, and resistance toheat is good.
Table 1
| Temperature ℃ | A thermal conductivity W/mk | B thermal conductivity W/mk |
| 100 | 0.72 | 4.93 |
| 200 | 0.69 | 4.54 |
| 400 | 0.68 | 3.89 |
| 600 | 0.63 | 3.53 |
| 800 | 0.62 | 3.06 |
Claims (10)
1. the preparation method of a foam silicon nitride ceramics, it is characterized in that preparing a kind of foam silicon nitride ceramics realizes according to the following steps: one, by volume per-cent mixes 5～8h with the water for ball milling of 30%～42% silicon nitride and 58%～70%, silicon nitride suspending liquid; Two, by volume per-cent mixes the gelifying agent of 85%～90% silicon nitride suspending liquid and 10%～15% down at 55～60 ℃ and stirs, mixed solution; Three, by volume per-cent mixes the coal fly ash hollow micro bead of 35%～65% mixed solution and 35%～65%, stirs 20～30min, viscosity be the suspension mucus of 0.5～1Pas; Four, suspension mucus is injected mould, at room temperature solidifies the demoulding behind dry 1～2h, then at room temperature ventilation drying 24～36h, dry back base substrate; Five, base substrate after the drying is put into atmosphere sintering furnace, fill shielding gas, under 0.1～0.3MPa pressure, be warmed up to 1500～1700 ℃ with 10～20 ℃ speed, sintering 1～2h promptly gets foam silicon nitride ceramics.
2. the preparation method of a kind of foam silicon nitride ceramics according to claim 1, the purity that it is characterized in that used silicon nitride raw material in the step 1 is 95～99%.
3. the preparation method of a kind of foam silicon nitride ceramics according to claim 2 is characterized in that in the step 1 that per-cent by volume mixes 6h with 40% silicon nitride and 60% water for ball milling.
4. the preparation method of a kind of foam silicon nitride ceramics according to claim 2 is characterized in that in the step 2 that per-cent by volume mixes the gelifying agent of 87% silicon nitride suspending liquid and 13% down at 58 ℃ to stir.
5. the preparation method of a kind of foam silicon nitride ceramics according to claim 2 is characterized in that the gelifying agent in the step 2 is the agarose solution of mass concentration 2～3% or the aqueous agar solution of mass concentration 2～5%.
6. the preparation method of a kind of foam silicon nitride ceramics according to claim 2 is characterized in that in the step 3 that per-cent by volume mixes 50% mixed solution and 50% coal fly ash hollow micro bead, stirs 25min, viscosity be the suspension mucus of 0.8Pas.
7. the preparation method of a kind of foam silicon nitride ceramics according to claim 2, the particle diameter that it is characterized in that used coal fly ash hollow micro bead ball in the step 3 is 40～200 μ m.
8. the preparation method of a kind of foam silicon nitride ceramics according to claim 2 is characterized in that solidifying in the step 4 demoulding, the dry 25h in the room temperature ventilation then behind the dry 1.5h.
9. the preparation method of a kind of foam silicon nitride ceramics according to claim 2 is characterized in that shielding gas is argon gas or nitrogen in the step 5.
10. the preparation method of a kind of foam silicon nitride ceramics according to claim 2 is characterized in that in the step 5 being warmed up to 1600 ℃ with 15 ℃ speed, sintering 1.5h under 0.2MPa pressure.
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| CN200710144954A CN100582059C (en) | 2007-12-28 | 2007-12-28 | Method for preparing foam silicon nitride ceramics |
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| CN200710144954A CN100582059C (en) | 2007-12-28 | 2007-12-28 | Method for preparing foam silicon nitride ceramics |
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| CN101215184A true CN101215184A (en) | 2008-07-09 |
| CN100582059C CN100582059C (en) | 2010-01-20 |
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Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101531538B (en) * | 2009-04-02 | 2011-12-28 | 哈尔滨工业大学 | Preparation method of near net-shape of porous silicon nitride/silicon oxynitride ceramic composite material |
| CN105835209A (en) * | 2016-04-01 | 2016-08-10 | 武汉工程大学 | Ceramic gel injection molding method based on agarose |
| CN106478113A (en) * | 2016-09-14 | 2017-03-08 | 郑州峰泰纳米材料有限公司 | Silicon nitride foamed ceramic and preparation method thereof |
| CN106631104A (en) * | 2016-09-14 | 2017-05-10 | 郑州峰泰纳米材料有限公司 | Foamed ceramic material and preparation method thereof |
| CN108298992A (en) * | 2018-03-06 | 2018-07-20 | 济南大学 | A kind of method that environment-friendly type gel casting forming prepares silicon nitride ceramics biscuit |
| CN114057509A (en) * | 2021-10-22 | 2022-02-18 | 中建六局(天津)绿色建筑科技有限公司 | Foamed ceramic with polished brick mud as main raw material and preparation method thereof |
-
2007
- 2007-12-28 CN CN200710144954A patent/CN100582059C/en not_active Expired - Fee Related
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101531538B (en) * | 2009-04-02 | 2011-12-28 | 哈尔滨工业大学 | Preparation method of near net-shape of porous silicon nitride/silicon oxynitride ceramic composite material |
| CN105835209A (en) * | 2016-04-01 | 2016-08-10 | 武汉工程大学 | Ceramic gel injection molding method based on agarose |
| CN105835209B (en) * | 2016-04-01 | 2018-05-01 | 武汉工程大学 | A kind of Ceramic gel injection moulding forming method based on agarose |
| CN106478113A (en) * | 2016-09-14 | 2017-03-08 | 郑州峰泰纳米材料有限公司 | Silicon nitride foamed ceramic and preparation method thereof |
| CN106631104A (en) * | 2016-09-14 | 2017-05-10 | 郑州峰泰纳米材料有限公司 | Foamed ceramic material and preparation method thereof |
| CN108298992A (en) * | 2018-03-06 | 2018-07-20 | 济南大学 | A kind of method that environment-friendly type gel casting forming prepares silicon nitride ceramics biscuit |
| CN114057509A (en) * | 2021-10-22 | 2022-02-18 | 中建六局(天津)绿色建筑科技有限公司 | Foamed ceramic with polished brick mud as main raw material and preparation method thereof |
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| Publication number | Publication date |
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| CN100582059C (en) | 2010-01-20 |
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