In-situ synthesized silicon nitride/zirconium boride composite ceramic and preparation method and application thereof
阅读说明：本技术 一种原位合成氮化硅/硼化锆复相陶瓷及其制备方法和应用 (In-situ synthesized silicon nitride/zirconium boride composite ceramic and preparation method and application thereof ) 是由 詹创添 吴利翔 牛文彬 朱林林 郭伟明 林华泰 于 2019-08-21 设计创作，主要内容包括：本发明属于于陶瓷材料技术领域,公开了一种原位合成氮化硅/硼化锆复相陶瓷及其制备方法和应用,所述氮化硅/硼化锆复相陶瓷是将预氧化的ZrB<Sub>2</Sub>、Si粉和烧结助剂MgO-Y<Sub>2</Sub>O<Sub>3</Sub>经混料,干燥后得到Si-ZrB<Sub>2</Sub>-MgO-Y<Sub>2</Sub>O<Sub>3</Sub>混合粉体；将混合粉体进行造粒和成型,再采用冷等静压制得Si-ZrB<Sub>2</Sub>-MgO-Y<Sub>2</Sub>O<Sub>3</Sub>坯体；将坯体在氮气气氛下,升温至1300～1450℃烧结,然后升温至1500～1600℃烧结并保温制得。本发明方法所制备的Si<Sub>3</Sub>N<Sub>4</Sub>-ZrB<Sub>2</Sub>复相陶瓷的相对密度为95～99％,硬度为18～25GPa,断裂韧性为10～15MPa·m<Sup>1/2</Sup>,抗弯强度为800～1200MPa。(the invention belongs to the technical field of ceramic materials, and discloses silicon nitride/zirconium boride complex phase ceramic synthesized in situ and a preparation method and application thereof, wherein the silicon nitride/zirconium boride complex phase ceramic is prepared by mixing pre-oxidized ZrB 2 , Si powder and a sintering aid MgO-Y 2 O 3 , drying to obtain Si-ZrB 2 -MgO-Y 2 O 3 mixed powder, granulating and molding the mixed powder, preparing a Si-ZrB 2 -MgO-Y 2 O 3 blank by adopting isostatic cool pressing, heating the blank to 1300-1450 ℃ in a nitrogen atmosphere for sintering, heating to 1500-1600 ℃ for sintering, and preserving heat.)
1. the in-situ synthesized silicon nitride/zirconium boride complex phase ceramic is characterized by being prepared by ball-milling and mixing pre-oxidized ZrB 2, Si powder and a sintering aid MgO-Y 2 O 3, drying to obtain Si-ZrB 2 -MgO-Y 2 O 3 mixed powder, granulating and molding the mixed powder, preparing a Si-ZrB 2 -MgO-Y 2 O 3 blank under the cold isostatic pressure of 100-300 MPa, heating the blank to 1300-1450 ℃ in the nitrogen atmosphere, and then heating to 1500-1600 ℃ for sintering.
2. The in-situ synthesized silicon nitride/zirconium boride composite ceramic as claimed in claim 1, wherein the relative density of the silicon nitride/zirconium boride composite ceramic is 95-99%, the hardness is 18-25 GPa, the fracture toughness is 10-15 MPa-m 1/2, and the bending strength is 800-1200 MPa.
3. The in-situ synthesized silicon nitride/zirconium boride composite ceramic as claimed in claim 1, wherein the mass ratio of the Si, the pre-oxidized ZrB 2 and the MgO-Y 2 O 3 is (50-98): (1-40): 1-10).
4. the in-situ synthesized silicon nitride/zirconium boride composite ceramic as claimed in claim 1, wherein the purity of the Si powder is 95-99%, the grain size of the Si powder is 0.1-10 μm, the purity of the ZrB 2 is 95-99%, the grain size of the ZrB 2 is 0.1-10 μm, the purity of the MgO powder is 98-100%, and the purity of the Y 2 O 3 is 98-00%.
5. The in-situ synthesized silicon nitride/zirconium boride composite ceramic as claimed in claim 1, wherein the pre-oxidized ZrB 2 is prepared by heat-insulating ZrB 2 at 500-1000 ℃ for 1-10 h.
6. The in-situ synthesized silicon nitride/zirconium boride composite ceramic as claimed in claim 1, wherein the mass ratio of MgO to Y 2 O 3 in MgO-Y 2 O 3 is (3-5) to (5-7).
7. The in-situ synthesized silicon nitride/zirconium boride composite ceramic as claimed in claim 1, wherein the sintering time after the temperature is raised to 1300-1450 ℃ is 0.5-4 h; the temperature is raised to 1500-1600 ℃ and the sintering time is 0.5-2 h.
8. The in-situ synthesized silicon nitride/zirconium boride composite ceramic as claimed in claim 1, wherein the rate of the temperature rise to 1300-1450 ℃ is 10-20 ℃/min; the rate of heating to 1500-1600 ℃ is 5-10 ℃/min.
9. The preparation method of the in-situ synthesized silicon nitride/zirconium boride composite ceramic according to any one of claims 1 to 8, characterized by comprising the following specific steps:
S1, performing ball milling and mixing on pre-oxidized ZrB 2, Si powder and a MgO-Y 2 O 3 sintering aid, and drying to obtain Si-ZrB 2 -MgO-Y 2 O 3 mixed powder;
S2, granulating the Si-ZrB 2 -MgO-Y 2 O 3 mixed powder, then forming the granulated powder, and maintaining the pressure at 100-300 MPa for 1-10 min through cold isostatic pressing to obtain a Si-ZrB 2 -MgO-Y 2 O 3 green body;
S3, heating the Si-ZrB 2 -MgO-Y 2 O 3 blank to 1300-1450 ℃ in a nitrogen atmosphere of 1-20 atm, sintering, and heating to 1500-1600 ℃ for sintering to obtain the silicon nitride/zirconium boride complex phase ceramic.
10. The application of the in-situ synthesized silicon nitride/zirconium boride complex-phase ceramic as claimed in any one of claims 1 to 8 in the fields of ceramic bearing balls, ceramic cutters or conductive ceramics.
Technical Field
The invention belongs to the technical field of ceramic materials, and particularly relates to silicon nitride/zirconium boride (Si 3 N 4 -ZrB 2) complex phase ceramic synthesized in situ, and a preparation method and application thereof.
Background
The Si 3 N 4 ceramic as a structural ceramic has excellent performances of high strength, high hardness, high toughness, wear resistance, high temperature resistance, high heat conductivity and the like, and is widely applied in the industry, generally, the Si 3 N 4 ceramic takes high-purity Si 3 N 4 powder as a raw material, and sintering aids are added to promote densification, but the preparation cost of the method is high.
In recent years, Si 3 N 4 ceramic is prepared by using Si powder as a raw material and sintering under reaction pressure, so that the cost is reduced, but the speed of nitriding the Si powder is relatively slow, and the densification of Si 3 N 4 formed after nitriding is difficult, so that high-density and high-performance Si 3 N 4 ceramic is difficult to obtain.
Disclosure of Invention
in order to overcome the disadvantages and shortcomings of the prior art, the present invention provides a silicon nitride/zirconium boride ceramic.
The invention also aims to provide a preparation method of the silicon nitride/zirconium boride ceramic.
The invention also aims to provide application of the silicon nitride/zirconium boride ceramic.
The purpose of the invention is realized by the following technical scheme:
a silicon nitride/zirconium boride complex phase ceramic is synthesized in situ, and is prepared by performing ball milling, mixing and drying on pre-oxidized ZrB 2, Si powder and a sintering aid MgO-Y 2 O 3 to obtain Si-ZrB 2 -MgO-Y 2 O 3 mixed powder, granulating and molding the mixed powder, maintaining the pressure at 100-300 MPa by adopting cold isostatic pressing to obtain a Si-ZrB 2 -MgO-Y 2 O 3 green body, heating the green body to 1300-1450 ℃ in a nitrogen atmosphere, sintering, and heating to 1500-1600 ℃ for sintering.
Preferably, the relative density of the silicon nitride/zirconium boride complex-phase ceramic is 95-99%, the hardness is 18-25 GPa, the fracture toughness is 10-15 MPa.m 1/2, and the bending strength is 800-1200 MPa.
Preferably, the mass ratio of the Si, the pre-oxidized ZrB 2 and the MgO-Y 2 O 3 is (50-98): (1-40): 1-10).
Preferably, the purity of the Si powder is 95-99%, the grain size of the Si powder is 0.1-10 μm, the purity of the ZrB 2 is 95-99%, the grain size of the ZrB 2 is 0.1-10 μm, the purity of the MgO powder is 98-100%, and the purity of the Y 2 O 3 is 98-00%.
Preferably, the pre-oxidized ZrB 2 is prepared by performing heat preservation on ZrB 2 at 500-1000 ℃ for 1-10 h.
Preferably, the mass ratio of MgO to Y 2 O 3 in the MgO-Y 2 O 3 is (3-5): 5-7).
Preferably, the time for sintering when the temperature is raised to 1300-1450 ℃ is 0.5-4 h; the temperature is raised to 1500-1600 ℃ and the sintering time is 0.5-2 h.
Preferably, the rate of heating to 1300-1450 ℃ is 10-20 ℃/min; the rate of heating to 1500-1600 ℃ is 5-10 ℃/min.
The preparation method of the in-situ synthesized silicon nitride/zirconium boride complex phase ceramic comprises the following specific steps:
S1, performing ball milling and mixing on pre-oxidized ZrB 2, Si powder and a MgO-Y 2 O 3 sintering aid, and drying to obtain Si-ZrB 2 -MgO-Y 2 O 3 mixed powder;
S2, granulating the Si-ZrB 2 -MgO-Y 2 O 3 mixed powder, then forming the granulated powder, and maintaining the pressure at 100-300 MPa for 1-10 min through cold isostatic pressing to obtain a Si-ZrB 2 -MgO-Y 2 O 3 green body;
S3, heating the Si-ZrB 2 -MgO-Y 2 O 3 blank to 1300-1450 ℃ in a nitrogen atmosphere of 1-20 atm, sintering, and heating to 1500-1600 ℃ for sintering to obtain the silicon nitride/zirconium boride complex phase ceramic.
The in-situ synthesized silicon nitride/zirconium boride complex phase ceramic is applied to the fields of ceramic bearing balls, ceramic cutters or conductive ceramics.
Compared with the prior art, the invention has the following beneficial effects:
1. The pre-oxidized ZrO 2 of the invention promotes the nitridation of Si powder and simultaneously introduces a ZrB 2 hard phase, the hardness of the silicon powder can be obviously improved by adding the hard phase ZrB 2 into Si 3 N 4, the ZrO 2 on the surface of ZrB 2 can be used as a nitridation auxiliary agent by pre-oxidizing ZrB 2, and the ZrB 2 hard phase is introduced while promoting the nitridation of Si powder.
2. According to the invention, the ZrB 2 hard conductive phase is introduced while the Si powder is nitrided, so that the mechanical property of the Si 3 N 4 ceramic is improved, the conductivity of the ceramic can be adjusted along with the addition of ZrB 2, the ZrB 2 is used as conductive ceramic, the Si 3 N 4 is used as insulating ceramic, and the conductivity is enhanced along with the increase of the content of ZrB 2.
Detailed Description
The following examples are presented to further illustrate the present invention and should not be construed as limiting the invention. Unless otherwise specified, the technical means used in the examples are conventional means well known to those skilled in the art. Reagents, methods and apparatus used in the present invention are conventional in the art unless otherwise indicated.
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