High-toughness silicon nitride ceramic and preparation method thereof
阅读说明：本技术 一种高韧性氮化硅陶瓷及其制备方法 (High-toughness silicon nitride ceramic and preparation method thereof ) 是由 曾宇平 梁汉琴 魏悦 左开慧 夏咏锋 姚冬旭 尹金伟 于 2020-04-26 设计创作，主要内容包括：本发明涉及一种高韧性氮化硅陶瓷及其制备方法,所述高韧性氮化硅陶瓷是以Si<Sub>3</Sub>N<Sub>4</Sub>作为主相,以SiC纤维、碳纤维、石墨烯、碳纳米管和YB<Sub>2</Sub>C<Sub>2</Sub>中的至少一种作为第二相,以及金属氧化物和稀土氧化物作为烧结助剂,经过烧结后得到。(The invention relates to a high-toughness silicon nitride ceramic and a preparation method thereof, wherein the high-toughness silicon nitride ceramic is prepared from Si 3 N 4 As a main phase, SiC fibers, carbon fibers, graphene, carbon nanotubes and YB are used 2 C 2 At least one of the metal oxide and the rare earth oxide is used as a second phase, and the metal oxide and the rare earth oxide are used as sintering aids, and the alloy is obtained after sintering.)
1. A high-toughness silicon nitride ceramic, wherein the high-toughness silicon nitride ceramic is Si3N4As a main phase, SiC fibers, carbon fibers, graphene, carbon nanotubes and YB are used2C2At least one of the metal oxide and the rare earth oxide is used as a second phase, and the metal oxide and the rare earth oxide are used as sintering aids, and the alloy is obtained after sintering.
2. The high toughness silicon nitride ceramic of claim 1 wherein said metal oxide is selected from the group consisting of Al2O3At least one of CaO and MgO; the rare earth oxide is RE2O3Preferably selected from Lu2O3、Yb2O3、Tm2O3And Er2O3At least one of (1).
3. The high-toughness silicon nitride ceramic according to claim 1 or 2, wherein the content of the sintering aid is 5 to 8wt% based on 100% by mass of the total of the main phase, the second phase and the sintering aid; preferably, the molar ratio of the metal oxide to the rare earth oxide is (3-1: 1), and more preferably 5: 3.
4. The high-toughness silicon nitride ceramic according to any one of claims 1 to 3, wherein the content of the second phase is 3 to 7wt% based on 100% by mass of the total of the main phase, the second phase and the sintering aid.
5. The high toughness silicon nitride ceramic of any of claims 1 through 4, wherein said second phase comprises at least one of SiC fibers, carbon nanotubes as one-dimensional reinforcing phase, and graphene and YB2C2As a two-dimensional reinforcing phase; preferably, the mass ratio of the one-dimensional reinforcing phase to the two-dimensional reinforcing phase is (1/6-6): 1.
6. the high-toughness silicon nitride ceramic according to any one of claims 1 to 5, wherein the SiC fibers have a diameter of 5 to 10 μm and a length of 25 to 50 μm, and preferably the aspect ratio of the SiC fibers is 5 to 10;
the diameter of the carbon fiber is 5-10 mu m, the length of the carbon fiber is 25-50 mu m, and the length-diameter ratio of the carbon fiber is preferably 5-10;
the inner diameter of the carbon nano tube is 1-5 nm, the length of the carbon nano tube is 0.1-0.5 mu m, and the length-diameter ratio of the carbon nano tube is preferably 20-100;
the size of the graphene is 300 nm-5 mu m;
the YB2C2The size of (A) is 300 nm-5 μm.
7. A method for producing a high toughness silicon nitride ceramic according to any one of claims 1 to 6, comprising:
(1) α -Si3N4Weighing and mixing the powder, the sintering aid and the second phase according to the mass ratio of (85-92) to (5-8) to (3-7), and then performing compression molding to obtain a biscuit;
(2) and putting the obtained biscuit into a graphite hot-pressing die, and putting the biscuit into a carbon tube furnace for sintering to obtain the high-toughness silicon nitride ceramic.
8. The method according to claim 7, wherein the reaction is carried out in the presence of a catalystCharacterized by being formed by α -Si3N4The particle size of the powder is 0.2-0.6 mu m; the particle size of the metal oxide is 0.2-0.5 mu m; the particle size of the rare earth oxide is 0.4-1.5 mu m.
9. The production method according to claim 7 or 8, wherein the sintering is performed by hot press sintering; the hot-pressing sintering temperature is 1700-1800 ℃, the heat preservation time is 1-3 hours, and the sintering pressure is 40-60 MPa; preferably, the heating rate of the hot-pressing sintering is 5-10 ℃/min.
10. An orthopedic implant material prepared from the high toughness silicon nitride ceramic of any of claims 1-6.
Technical Field
The invention relates to a high-toughness silicon nitride ceramic and a preparation method thereof, in particular to a silicon nitride ceramic prepared from Si3N4Is a main phase, Al2O3And RE2O3(RE2O3Is Lu2O3、Yb2O3、Tm2O3And Er2O3One or more of) and the like as sintering aids, at least one of SiC fibers, carbon fibers and carbon nanotubes as a one-dimensional reinforcing phase, and graphene and YB2C2As a two-dimensional reinforcing phase to prepare high-toughness Si3N4Method of ceramic of Si3N4The field of ceramic preparation.
Background
Silicon nitride ceramics are known to have the advantages of high strength, high toughness, high hardness, corrosion resistance, wear resistance and the like, and are widely applied to various industrial departments. Researches show that the silicon nitride ceramics also have excellent biological safety, so the silicon nitride ceramics are gradually paid attention to the medical appliance industry and are expected to be used as orthopedic implants such as hip joint bulbs and the like. For example, a patent (chinese publication No. CN103435356A) discloses a method for preparing a silicon nitride artificial ceramic joint by gelcasting and pressureless sintering. This patent only examines the forming process, components and the like of the silicon nitride ceramics, but does not specifically examine the properties of the silicon nitride ceramics, such as fracture toughness and the like, which is disadvantageous in giving full cognizance to the service performance of the silicon nitride ceramics. A patent (chinese publication No. CN 108585880a) discloses a method for preparing a silicon nitride ceramic hip joint ball, which has made some studies on molding and sintering conditions, but also fails to examine fracture toughness of silicon nitride ceramic, which is not favorable for establishing the relationship among components, preparation methods and properties of silicon nitride ceramic.
Silicon nitride ceramics, as a long-life orthopedic implant, need to have excellent fracture toughness to ensure that they do not crack or fail during routine use, avoiding secondary damage that could cause re-implantation or repair.A silicon nitride ceramic has two common crystal structures, α and β. α -Si during sintering3N4Will dissolve in the liquid phase formed by the sintering aid and then separate out β -Si from the liquid phase3N4，β-Si3N4Therefore, in order to improve the fracture toughness of the silicon nitride ceramic, the prior art generally selects the silicon nitride ceramic capable of effectively promoting α - β Si3N4The phase transformation sintering aid enables the phase transformation to be more sufficient.
Disclosure of Invention
Therefore, the invention provides a high-toughness silicon nitride ceramic and a preparation method thereof, and particularly a second phase capable of exciting more toughening mechanisms is doped into a silicon nitride ceramic matrix so as to effectively improve the fracture toughness of the silicon nitride ceramic.
In one aspect, the present invention provides a high toughness silicon nitride ceramic that is formed from Si3N4As a main phase, SiC fibers, carbon fibers, graphene, carbon nanotubes and YB are used2C2At least one of the metal oxide and the rare earth oxide is used as a second phase, and the metal oxide and the rare earth oxide are used as sintering aids, and the alloy is obtained after sintering.
In the present disclosure, Si is effectively promoted by selection3N4The sintering aid for crystal transformation promotes α -Si in the sintering process3N4To β -Si3N4So that the phase of the ceramic is changedLarge amount of β -Si in the form of long column3N4The crystal grains are mutually staggered to form a space network structure, thereby achieving the purpose of self-toughening. Meanwhile, a second phase capable of exciting more toughening mechanisms is doped to synergistically improve the fracture toughness of the silicon nitride ceramic. Specifically, metal oxides and rare earth oxides are used as sintering aids to promote densification and phase transformation; simultaneously, SiC fibers, carbon fibers, graphene, carbon nanotubes or YB are doped2C2To improve the fracture toughness of the silicon nitride ceramic.
Preferably, the metal oxide is selected from Al2O3At least one of CaO and MgO; the rare earth oxide is RE2O3Preferably selected from Lu2O3、Yb2O3、Tm2O3And Er2O3At least one of (1).
Preferably, the total mass of the main phase, the second phase and the sintering aid is 100%, and the content of the sintering aid is 5-8 wt%; preferably, the molar ratio of the metal oxide to the rare earth oxide is (3-1: 1), and more preferably 5: 3.
Preferably, the total mass of the main phase, the second phase and the sintering aid is 100%, and the content of the second phase is 3-7 wt%.
Preferably, the second phase comprises at least one of SiC fiber, carbon fiber and carbon nanotube as a one-dimensional reinforcing phase, and graphene and YB2C2As a two-dimensional reinforcing phase; preferably, the mass ratio of the one-dimensional reinforcing phase to the two-dimensional reinforcing phase is (1/6-6): 1.
preferably, the diameter of the SiC fiber is 5-10 μm, the length of the SiC fiber is 25-50 μm, and the length-diameter ratio of the SiC fiber is preferably 5-10;
the diameter of the carbon fiber is 5-10 mu m, the length of the carbon fiber is 25-50 mu m, and the length-diameter ratio of the carbon fiber is preferably 5-10;
the inner diameter of the carbon nano tube is 1-5 nm, the length of the carbon nano tube is 0.1-0.5 mu m, and the length-diameter ratio of the carbon nano tube is preferably 20-100;
the size of the graphene is 300 nm-5 mu m;
the YB2C2The size of (A) is 300 nm-5 μm.
In another aspect, the present invention provides a method for preparing the high-toughness silicon nitride ceramic, including:
(1) α -Si3N4Weighing and mixing the powder, the sintering aid and the second phase according to the mass ratio of (85-92) to (5-8) to (3-7), and then performing compression molding to obtain a biscuit;
(2) and putting the obtained biscuit into a graphite hot-pressing die, and putting the biscuit into a carbon tube furnace for sintering to obtain the high-toughness silicon nitride ceramic.
Preferably, the α -Si is3N4The particle size of the powder is 0.2-0.6 mu m; the particle size of the metal oxide is 0.2-0.5 mu m; the particle size of the rare earth oxide is 0.4-1.5 mu m.
Preferably, the sintering mode is hot-pressing sintering; the hot-pressing sintering temperature is 1700-1800 ℃, the heat preservation time is 1-3 hours, and the sintering pressure is 40-60 MPa; preferably, the heating rate of the hot-pressing sintering is 5-10 ℃/min.
In another aspect, the invention also provides an orthopedic implant material prepared from the high-toughness silicon nitride ceramic.
Has the advantages that:
the invention is achieved by using metal oxides (e.g., Al)2O3) And RE2O3(RE2O3Is Lu2O3、Yb2O3、Tm2O3And Er2O3One or more of) as a sintering aid, can effectively promote α - β Si while realizing densification of silicon nitride ceramics3N4So that β -Si with long columnar structure is completely formed in the matrix3N4(ii) a In addition, by adding SiC fibers, carbon fibers, graphene, carbon nanotubes or YB2C2One or more of which is a second phase that enhances toughness, more toughening mechanisms are activated in the silicon nitride ceramic, such as crack deflection, crack branching, and whisker pulling, to achieve high toughnessSexual Si3N4A ceramic.
Drawings
FIG. 1 shows Si obtained in example 13N4Phase analysis of ceramics;
FIG. 2 shows YB in example 22C2The topography of (1).
Detailed Description
The present invention is further illustrated by the following examples, which are to be understood as merely illustrative and not restrictive.
In the present disclosure, the high toughness silicon nitride ceramic comprises Si3N4The main phase, the metal oxide and the rare earth oxide are used as sintering aids, and the second phase for improving the toughness is prepared by sintering.
In alternative embodiments, the metal oxide may be CaO, MgO, Al2O3And the like. The rare earth oxide can be Lu2O3、Yb2O3、Tm2O3And Er2O3Sintering of silicon nitride ceramic and α -Si3N4To β -Si3N4The smaller the radius of the rare earth cation, the larger the cation field strength, and thus the higher the viscosity of the formed liquid phase, and the longer the mass transfer time in the liquid phase, β -Si3N4The crystal grains have more sufficient time to grow into the crystal grains with high aspect ratio, and the space network structure formed by the staggered crystal grains is firmer.
In an alternative embodiment, the second phases may be classified by dimension into one-dimensional enhancement phases and two-dimensional enhancement phases. Wherein, the length-diameter ratio of the one-dimensional reinforcing phase can be 5-10, such as carbon fiber, carbon nano tube, SiC fiber and the like. The two-dimensional reinforcing phase may have a particle size distribution of 300nm to 5 μm, e.g. graphene, YB2C2And the like. The toughness-enhancing second phase content may be 3 to 7 wt.%. If the addition amount is too large, the densification of the silicon nitride ceramic is obviously influenced. If the addition amount is small, the toughness is not obviously improved.
The following is an exemplary description of the preparation of high toughness silicon nitride ceramics.
α -Si3N4Powder and sintering aid (Al)2O3Powder and RE2O3Powder) and the second phase to obtain raw material powder. Preferably Al2O3And RE2O3Is fixed at a molar ratio of 5:3, as an example, according to α -Si3N4Powder: sintering aid: weighing the second phase (85-92) to (5-8) to (3-7) in mass ratio, adding alcohol to prepare slurry with certain solid content, and performing ball milling treatment. And finally, drying and sieving the slurry obtained after ball milling treatment to obtain raw material powder. Wherein the solid content of the slurry can be 45-55 wt%. The rotation number of the ball milling treatment can be 250-350rpm, and the ball milling time can be 3-5 hours. The drying temperature can be 110-130 ℃, and the drying time can be 2-6 hours. Wherein, the sieving can be a sieve with 100 meshes to 400 meshes.
In an alternative embodiment, α -Si3N4The particle size of the powder can be 0.2-0.6 μm. Al (Al)2O3The particle size of the powder can be 0.2-0.5 μm. RE2O3The particle size of the powder can be 0.4-1.5 μm. It should be noted that the particle size of the other metal oxides may be 0.2 to 0.5 μm.
And pressing and molding the raw material powder to obtain a biscuit. The pressure of the dry pressing preforming can be 10-30 MPa.
And putting the biscuit into a graphite hot-pressing mold, and putting the biscuit into a carbon tube furnace to be sintered in a nitrogen atmosphere to obtain the high-toughness silicon nitride ceramic. The sintering mode can be hot-pressing sintering and the like. As an example, the hot-pressing sintering temperature is 1700-1800 ℃, the heating rate is 5-10 ℃/min, the heat preservation time is 1-3 h, and the sintering pressure is 40-60 MPa.
In the invention, Si is obtained by adopting an Archimedes drainage method for testing3N4The density of the ceramic is 97.5 to 99.6g/cm3。
In the invention, Si is obtained by adopting a single-side open beam method for testing3N4The ceramic has a fracture toughness of 7.9 to 13.6MPa m1/2。
In the present invention, Si prepared by the above-mentioned preparation method is used3N4The ceramic has the advantages of high toughness and the like, can be used for manufacturing hip joint ball heads, and has longer service life.
The present invention will be described in detail by way of examples. It is also to be understood that the following examples are illustrative of the present invention and are not to be construed as limiting the scope of the invention, and that certain insubstantial modifications and adaptations of the invention by those skilled in the art may be made in light of the above teachings. The specific process parameters and the like of the following examples are also only one example of suitable ranges, i.e., those skilled in the art can select the appropriate ranges through the description herein, and are not limited to the specific values exemplified below. Si used in the following examples and comparative examples unless otherwise specified3N4The powder is α -Si3N4And (3) powder.
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