WO2024059987A1 - 一种可变形氮化硅陶瓷的制备方法 - Google Patents

一种可变形氮化硅陶瓷的制备方法 Download PDF

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WO2024059987A1
WO2024059987A1 PCT/CN2022/119738 CN2022119738W WO2024059987A1 WO 2024059987 A1 WO2024059987 A1 WO 2024059987A1 CN 2022119738 W CN2022119738 W CN 2022119738W WO 2024059987 A1 WO2024059987 A1 WO 2024059987A1
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sintering
silicon nitride
preparation
ceramic
phase
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French (fr)
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刘光华
张�杰
杜松墨
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清华大学
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    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • 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
    • C04B35/58—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 borides, nitrides, i.e. nitrides, oxynitrides, carbonitrides or oxycarbonitrides or silicides
    • C04B35/584—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 borides, nitrides, i.e. nitrides, oxynitrides, carbonitrides or oxycarbonitrides or silicides based on silicon nitride
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
    • C04B35/622—Forming processes; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
    • C04B35/64—Burning or sintering processes

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  • the invention belongs to the technical field of ceramic preparation, and relates to a method for preparing variable silicon nitride ceramics, and in particular to a method for preparing silicon nitride ceramics with alpha/beta coherent structure.
  • Silicon nitride ceramics have many excellent properties such as low density, high thermal conductivity, high hardness, good thermal stability and chemical stability. It is a material with the best comprehensive performance in the structural ceramic family and is widely used in ceramic engines, Cutting tools, thermal conductive substrates and other fields. However, the inherent brittleness of ceramic materials limits the further application and promotion of silicon nitride. Therefore, it is of great significance to develop ceramic materials with high fracture toughness.
  • the object of the present invention is to provide a method for preparing deformable silicon nitride ceramics.
  • the deformable silicon nitride ceramic obtained by this method has a relative density of >99%, a fracture toughness of >8MPa ⁇ m 1/2 , a Vickers hardness of >18Gpa, and a flexural strength of >600MPa.
  • the ceramic can withstand a maximum of 32% The strain does not cause damage.
  • the preparation method of deformable silicon nitride ceramics provided by the invention includes the following steps:
  • step 2) Sinter the mixture obtained in step 1) to obtain a deformable silicon nitride ceramic with an ⁇ / ⁇ coherent structure.
  • the purity of the ⁇ -phase silicon nitride powder is >99wt%; the purity mentioned here refers to the content of other impurities (O, Fe, Al, Ca, Mg, etc.) ⁇ 1wt%, and the remaining 99%
  • the above are all silicon nitride (Si 3 N 4 ).
  • the average particle size of the ⁇ -phase silicon nitride powder is 0.2-10 ⁇ m, and the ⁇ -phase content in the silicon nitride powder is >90wt%.
  • the sintering aid is selected from one or more of Al 2 O 3 , MgO, SiO 2 , Y 2 O 3 , ZrO 2 , RE 2 O 3 (rare earth oxide), MgSiN 2, wherein RE represents a rare earth element; specifically, the sintering aid may be composed of Al 2 O 3 and Y 2 O 3 , and the mass ratio of the two may be 60%:40%; or, the sintering aid may also be composed of La 2 O 3 and MgO, and the mass ratio of the two may be 80%:20%.
  • the purity of the sintering aid is >99wt%, and the average particle size of the sintering aid is 300-500nm.
  • the mass percentage of ⁇ -phase silicon nitride powder in the mixture may be 70 wt%, 80 wt% or 95 wt%;
  • the mass percentage of the sintering aid in the mixture may be 30wt%, 20wt% or 5wt%.
  • the component may also include a phase change inhibitor.
  • the phase change inhibitor is selected from one or more of CaO and RE 2 O 3 , where RE represents a rare earth element.
  • the mass percentage of the phase change inhibitor is 0-10wt%; according to an embodiment of the present invention, the mass percentage of the phase change inhibitor in the mixture can be 2w%, 5w% or 10w%.
  • the mixing includes sand milling, ball milling or stirring mill; the medium used is selected from any one of water, methanol and ethanol; the grinding ball for sanding is selected from silicon nitride grinding ball , one of zirconia grinding balls and agate grinding balls, wherein the grinding ball size is ⁇ 1mm; the grinding balls of the ball mill are silicon nitride grinding balls, and the grinding ball size is 3-10mm; the grinding balls of the stirring mill are Silicon nitride grinding balls, grinding ball size is 3-10mm.
  • step 1) of the above method the mixing speed is 300-3000r/min, and the mixing time is 2-24h.
  • the sintering method is selected from one or more of the following sintering methods: rapid hot press sintering, discharge plasma sintering, hot press sintering, hot isostatic pressing sintering, air pressure sintering or oscillating pressure sintering. .
  • the sintering method is a rapid hot pressing sintering method.
  • the specific preparation method is: first dry the mixture obtained in step (1), pass it through a 60-200 mesh sieve, load it into a sintering mold, and then place the mold in a rapid hot-pressing sintering device. After vacuuming, add the raw materials. Press and energize at the same time for sintering.
  • the sintering can be carried out in a vacuum, nitrogen or argon atmosphere.
  • the temperature rise rate of rapid hot pressing sintering is 1000-5000°C/min (specifically, 3000°C/min); after the reaction sintering is completed, the sample It is cooled with the furnace, and a sintered product is obtained after cooling; the sintering pressure range is 10-100MPa (specifically such as 30MPa), the sintering temperature is 1500-1800°C (specifically such as 1550°C), and the holding time is 1-5min (specifically such as 5min).
  • the sintering method is a discharge plasma sintering method.
  • the specific preparation method is: first dry the mixture obtained in step (1), pass it through a 60-200 mesh sieve, load it into a sintering mold, and then put the mold into a discharge plasma sintering device. After vacuuming, add the raw materials. Pressure, while electrical heating is performed for sintering.
  • the sintering can be performed in a vacuum, nitrogen or argon atmosphere.
  • the temperature rise rate of discharge plasma sintering is 150-200°C/min (specifically, 150°C); after the reaction sintering is completed, the sample is processed with the furnace.
  • the sintering pressure range is 10-100MPa (specifically, such as 30MPa)
  • the sintering temperature is 1500-1800°C (specifically, such as 1500°C)
  • the holding time is 1-5min (specifically, such as 5min).
  • the sintering method is a hot isostatic pressing sintering method.
  • the specific preparation method is: first dry the mixture obtained in step (1), pass it through a 60-200 mesh sieve, and then dry-press the mixed powder into shape at a pressure of 1-50 MPa and maintain the pressure for 1-5 minutes, and then dry-press the molded powder.
  • the billet is cold isostatically pressed at a pressure of 200-800MPa, and the pressure is maintained for 1-5mim.
  • the resultant is then placed in a boron nitride crucible and put together into a hot isostatic pressing sintering furnace. In the sintering furnace, the temperature is 5-20°C.
  • the temperature is raised to 1500-1800°C (specifically such as 1600°C) at a speed of /min (specifically such as 10°C/min), and the temperature is maintained for 0.5-8h (specifically such as 4h).
  • the sintering is carried out in a nitrogen or argon atmosphere.
  • the heat is isostatic
  • the pressure of pressure sintering is 0-500MPa.
  • the sintering method is a hot press sintering method and an oscillating pressure sintering method.
  • the specific preparation method is: first dry the mixture obtained in step (1), pass it through a 60-200 mesh sieve, load it into a sintering mold, then place the reaction mold in a sintering device, and after vacuuming, pressurize the raw materials. At the same time, the heating element is electrically heated for sintering.
  • an oscillating pressure is applied to the sample based on the original pressure.
  • the pressure oscillation amplitude is 1-50MPa.
  • the sintering can be carried out in a vacuum, nitrogen or argon atmosphere; after the reaction is completed, the sample is placed in the furnace. Cooling is carried out; after cooling, a sintering product is obtained; the sintering pressure range is 10-200MPa, the temperature is raised to 1500-1800°C at a speed of 5-20°C/min, and the holding time is 0.5-8h.
  • the deformable silicon nitride ceramics prepared by the above method all belong to the protection method of the present invention.
  • the relative density of the deformable silicon nitride ceramic is >99%, the fracture toughness is >8MPa ⁇ m 1/2 , the Vickers hardness is >17Gpa, and the flexural strength is >600MPa.
  • the deformable silicon nitride ceramic prepared by the method of the present invention contains an ⁇ / ⁇ coherent structure, and the content of the ⁇ / ⁇ coherent structure can be 10-70%, and further can be 20-30%.
  • the spatial orientation of ⁇ grains and ⁇ grains in the ⁇ / ⁇ coherent structure of the present invention is consistent, and the ⁇ and ⁇ grains are bonded by covalent bonds rather than by glass phase adhesion. Therefore, there is no glass phase between the grains of the ⁇ / ⁇ coherent structure.
  • the silicon nitride ceramic prepared in the present invention can withstand macroscopic 1-3% strain without fracture; when the size of silicon nitride is ⁇ 1 ⁇ m, it can withstand 10-40% strain without fracture. .
  • the silicon nitride ceramic prepared by the present invention has an ⁇ / ⁇ coherent structure, and its outstanding advantages are:
  • the silicon nitride ceramic with ⁇ / ⁇ coherent structure prepared by the method of the present invention can transform from ⁇ phase to ⁇ phase under load conditions, and the ⁇ grain size continuously decreases during the phase transformation process. Small, so that the grain size of silicon nitride ceramics continues to decrease, which plays the role of fine grain strengthening;
  • the silicon nitride ceramic with ⁇ / ⁇ coherent structure prepared by the method of the present invention under the condition of bearing load, the interior of the silicon nitride undergoes the disconnection, reorganization and conversion of covalent bonds, and atomic vibration. , rotation and other processes realize the phase transition from ⁇ phase to ⁇ phase. This process is accompanied by shear between atomic layers, thus providing a basis for ceramic deformation;
  • the silicon nitride preparation method of the present invention has a simple and efficient preparation process. Compared with the traditional process for preparing silicon nitride, the sintering temperature of the present invention is reduced by 100-200°C and the time is shortened by 5-10 hours.
  • Figure 1 is the XRD analysis pattern of the silicon nitride powder raw material used in Examples 1-3;
  • Figure 2 is the XRD analysis pattern of silicon nitride ceramics in Example 1;
  • Figure 3 is a coherent structure distribution diagram of the silicon nitride ceramic in Example 1;
  • Figure 4 is a SEM analysis pattern of the silicon nitride ceramic product in Example 1;
  • Figure 5 is the stress strain curve of the silicon nitride ceramic product in Example 1;
  • Figure 6 is the XRD analysis pattern of the silicon nitride ceramic product in Example 2.
  • FIG7 is a SEM analysis spectrum of the silicon nitride ceramic product in Example 2.
  • Figure 8 is the XRD analysis pattern of the silicon nitride ceramic product in Example 3.
  • Figure 9 is the XRD analysis pattern of the silicon nitride ceramic product in Comparative Example 1;
  • Figure 10 is a compression comparison chart of the products of Example 1 and Comparative Example 1.
  • the flexural strength test of the silicon nitride ceramic is tested according to the standard GB/T 6569-2006, the hardness test is tested according to the standard GB/T 16534-2009, and the fracture toughness test is tested according to the standard GB/T 23806-2009.
  • the ⁇ phase content is measured by X-ray diffraction (XRD); the ⁇ / ⁇ coherent structure content is measured by precession electron diffraction (PED) or transmission Kikuchi diffraction (TKD).
  • the purity of the ⁇ -phase silicon nitride powder is >99wt%; the average particle size of the ⁇ -phase silicon nitride powder is 0.2-10 ⁇ m; and the purity of the ⁇ -phase in the ⁇ -phase silicon nitride powder is >90wt%.
  • the purity of the sintering aids used is >99wt%, and the average particle size of each sintering aid is 300-500nm.
  • the ceramic raw material is composed of the following components in mass percentage:
  • ⁇ -phase silicon nitride powder 95%
  • the sintering aid is composed of the following components in percentage by mass:
  • Figures 2-4 are characterization diagrams of silicon nitride ceramics prepared in Example 1. As shown in Figure 2, the ⁇ phase content is 49%, as shown in Figure 3, the ⁇ / ⁇ coherent structure content is 30%, and as shown in Figure 4, the grain size after sintering is about 200-500nm, which is consistent with Figure 3.
  • Figure 5 is the stress strain curve of the silicon nitride ceramic prepared in Example 1. It can be seen from the figure that the test sample reaches a maximum strain of 32%, and the stress it bears at this time can reach 10GPa.
  • the ceramic raw material is composed of the following components in mass percentage:
  • ⁇ -phase silicon nitride powder 80%;
  • the sintering aid is composed of the following components in mass percentage:
  • the ceramic raw material is composed of the following components in mass percentage:
  • ⁇ -phase silicon nitride powder 70%
  • Phase change inhibitor 10%
  • the phase change inhibitor is composed of the following mass percentage components: 5% CaO+5% Lu 2 O 3 ;
  • the sintering aid is composed of the following components in mass percentage:
  • the ceramic raw material is composed of the following components in mass percentage:
  • Beta phase silicon nitride powder 95%
  • the sintering aid is composed of the following components in mass percentage:
  • Silicon nitride powder 80%;
  • Phase change inhibitor 5%
  • the sintering aid consists of the following components: MgO: 40%; Y 2 O 3 : 40%; SiO 2 : 20%;
  • the ⁇ phase content of the obtained ceramic is 50%, the relative density is 99.4%, the fracture toughness is 10.5MPa ⁇ m 1/2 , the Vickers hardness is 19.3Gpa, and the flexural strength is 745MPa. For samples with a size ⁇ 1 ⁇ m, it can withstand a maximum strain of 8% without causing damage.
  • Example 1 uses ⁇ -phase silicon nitride powder as the raw material to obtain ⁇ / ⁇ co-existence.
  • the silicon nitride ceramic has a lattice structure content of 30%, while Comparative Example 1 does not have an ⁇ / ⁇ coherent structure.
  • the fracture toughness of the final sintered product increased from 5MPa ⁇ m 1/2 in Comparative Example 1 to 10MPa ⁇ m 1/2 in Example 1, and the Vickers hardness increased from 16.3Gpa in Comparative Example 1 to that in Example 1. 1 of 23.1Gpa.
  • Comparative Example 1 does not have the ability to withstand strain, while Example 1 can withstand a maximum strain of 32% without causing fracture.
  • the compression comparison chart of the products of Example 1 and Comparative Example 1 is shown in Figure 10. It can be seen from the figure that the sample with ⁇ / ⁇ coherent structure undergoes obvious plastic deformation and does not fail at 20% strain. The sample without ⁇ / ⁇ coherent structure does not undergo plastic deformation or undergoes brittle fracture. It can be seen that the silicon nitride ceramic with ⁇ / ⁇ coherent structure prepared using the preparation process of the present invention can greatly improve the mechanical properties of the silicon nitride ceramic. Based on this preparation method, a silicon nitride ceramic with excellent performance can be obtained .
  • the silicon nitride ceramic with an ⁇ / ⁇ coherent structure prepared by the present invention under the condition of bearing a load, realizes the process of disconnection, reorganization and conversion of covalent bonds inside the silicon nitride, as well as atomic vibration, rotation and other processes.
  • the phase transformation from ⁇ phase to ⁇ phase is accompanied by shear between atomic layers, thus providing the basis for ceramic deformation.

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Abstract

本发明公开了一种可变形氮化硅陶瓷的制备方法。该方法包括以下步骤：1)将氮化硅原料及烧结助剂等按照比例混合，混合均匀后的粉末通过快速烧结，将氮化硅烧结过程中的相变组织保留下来，获得相对密度>99％的烧结体，从而生成α/β共格组织。本发明方法使氮化硅材料中形成α和β相的共格组织，α与β的空间取向一致，α与β晶粒之间通过共价键结合，而非通过玻璃相粘连，从而获得一种可变形氮化硅陶瓷。该陶瓷的相对密度>99％，断裂韧性>8MPa·m 1/2，维氏硬度>18Gpa，抗弯强度>600MPa，特别地，该陶瓷能够最大承受32％的应变不发生破坏。本发明制备的氮化硅陶瓷除具备传统氮化硅陶瓷(强度高、致密性好、耐高温、耐磨)的特点外，断裂韧性及塑性得到明显提高，可广泛应用于特种材料领域。

Description

一种可变形氮化硅陶瓷的制备方法 技术领域
本发明属于陶瓷制备技术领域，涉及一种可变性氮化硅陶瓷的制备方法，特别涉及一种制备具有α/β共格组织的氮化硅陶瓷的方法。
背景技术
氮化硅陶瓷具有低密度、高导热系数、高硬度、良好的热稳定性和化学稳定性等多种优异性能，是结构陶瓷家族中综合性能最为优良的一类材料，广泛应用于陶瓷发动机、切削刀具、导热基板等领域。然而，陶瓷材料固有的脆性却限制了氮化硅的进一步应用与推广。因此，开发具有高断裂韧性的陶瓷材料具有重要的意义。
发明公开
本发明的目的是提供一种可变形氮化硅陶瓷的制备方法。该方法得到的可变形氮化硅陶瓷，其相对密度>99％，断裂韧性>8MPa·m 1/2，维氏硬度>18Gpa，抗弯强度>600MPa，特别地，该陶瓷能够最大承受32％的应变不发生破坏。
本发明所提供的可变形氮化硅陶瓷的制备方法，包括下述步骤：
1)准备原料：
将下述质量百分含量的组分混合均匀，得到混合物；
α相氮化硅粉70-98wt％，
烧结助剂2-30wt％，
2)将步骤1)所得混合物进行烧结，得到具有α/β共格组织的可变形氮化硅陶瓷。
上述方法步骤1)中，所述α相氮化硅粉的纯度>99wt％；此处所述纯度是指其他杂质(O，Fe，Al，Ca，Mg等)含量<1wt％，其余99％以上均为氮化硅(Si 3N 4)。所述α相氮化硅粉的平均粒径0.2-10μm，氮化硅粉中α相含量>90wt％。
上述方法步骤1)中，所述烧结助剂选自Al 2O 3、MgO、SiO 2、Y 2O 3、ZrO 2、RE 2O 3(稀土氧化物)、MgSiN 2中的一种或多种，其中RE代表稀土元素；具体的，所述烧结助剂可由Al 2O 3和Y 2O 3组成，两者的质量比可为60％：40％；或者，所述烧结助剂也可由La 2O 3和MgO组成，两者的质量比可为80％：20％。
所述烧结助剂的纯度>99wt％，所述烧结助剂平均粒度为300-500nm。
根据本发明的一种实施方式，所述混合物中α相氮化硅粉的质量百分含量可为70 wt％、80wt％或95wt％；
根据本发明的一种实施方式，所述混合物中烧结助剂的质量百分含量可为30wt％、20wt％或5wt％。
进一步的，所述组分还可包括相变抑制剂。所述相变抑制剂选用CaO、RE 2O 3中的一种或多种，其中RE代表稀土元素。
所述相变抑制剂的质量百分含量为0-10wt％；根据本发明的一种实施方式，所述混合物中相变抑制剂的质量百分含量可为2w％、5w％或10w％。
上述方法步骤1)中，所述的混合包括砂磨、球磨或搅拌磨；使用的介质选自水、甲醇、乙醇中的任一种；所述砂磨的磨球选自氮化硅磨球、氧化锆磨球、玛瑙磨球中的一种，其中磨球尺寸<1mm；所述球磨的磨球为氮化硅磨球，磨球尺寸为3-10mm；所述搅拌磨的磨球为氮化硅磨球，磨球尺寸为3-10mm。
上述方法步骤1)中，所述的混合，其转速为300-3000r/min，混料时间为2-24h。
上述方法步骤2)中，所述的烧结方法选自下述一种或多种烧结方法：快速热压烧结、放电等离子体烧结、热压烧结、热等静压烧结、气压烧结或震荡压力烧结。
根据本发明的一种实施方式，所述的烧结方法为快速热压烧结法。具体制备方法为：先将步骤(1)所得混合物干燥，过60-200目筛，装料于烧结模具内，再将所述模具放置在快速热压烧结装置内，抽真空后，对原料加压，同时通电加热进行烧结，烧结可以在真空、氮气或氩气气氛下进行，快速热压烧结的升温速率为1000-5000℃/min(具体如3000℃/min)；反应烧结结束后，样品随炉进行冷却，冷却后得到烧结产物；所述烧结的压力范围为10-100MPa(具体如30MPa)，烧结温度为1500-1800℃(具体如1550℃)，保温时间为1-5min(具体如5min)。
根据本发明的一种实施方式，所述的烧结方法为放电等离子体烧结法。具体制备方法为：先将步骤(1)所得混合物干燥，过60-200目筛，装料于烧结模具内，再将所述模具装入放电等离子体烧结装置内，抽真空后，对原料加压，同时通电加热进行烧结，烧结可以在真空、氮气或氩气气氛下进行，放电等离子体烧结升温速率为150-200℃/min(具体如150℃)；反应烧结结束后，样品随炉进行冷却，冷却后得到烧结产物；所述烧结的压力范围为10-100MPa(具体如30MPa)，烧结温度为1500-1800℃(具体如1500℃)，保温时间为1-5min(具体如5min)。
根据本发明的一种实施方式，所述的烧结方法为热等静压烧结法。具体制备方法为：先将步骤(1)所得混合物干燥，过60-200目筛，然后将混合粉末进行干压成型，压力为1-50MPa，保压1-5min，再将干压成型的素坯进行冷等静压，压力为200-800MPa， 保压1-5mim，然后将所得物置于氮化硼坩埚内，一起放入热等静压烧结炉中，在烧结炉中以5-20℃/min(具体如10℃/min)的速度升温至1500-1800℃(具体如1600℃)，保温0.5-8h(具体如4h)，烧结在氮气，氩气气氛下进行，所述热等静压烧结的压力为0-500MPa。
根据本发明的一种实施方式，所述的烧结方法为热压烧结法与震荡压力烧结法。具体制备方法为：先将步骤(1)所得混合物干燥，过60-200目筛，装料于烧结模具内，然后将所述反应模具放置在烧结装置内，抽真空后，对原料加压，同时发热体通电加热进行烧结，在烧结过程中在原有压力基础上对样品施加震荡压力，压力震荡幅度1-50MPa，烧结可以在真空、氮气或氩气气氛下进行；反应结束后，样品随炉进行冷却；冷却后得到烧结产物；所述烧结压力范围为10-200MPa，以5-20℃/min的速度升温至1500-1800℃，保温时间为0.5-8h。
上述方法制备得到的可变形氮化硅陶瓷均属于本发明的保护方法。
所述可变形氮化硅陶瓷的相对密度>99％，断裂韧性>8MPa·m 1/2，维氏硬度>17Gpa，抗弯强度>600MPa。
本发明方法制备得到的可变形氮化硅陶瓷，其含有α/β共格组织，所述α/β共格组织的含量可为10-70％，进一步可为20-30％。
本发明所述的α/β共格组织中α晶粒与β晶粒的空间取向一致，α与β晶粒之间通过共价键结合，而非通过玻璃相粘连，因此，α/β共格组织的晶粒间不存在玻璃相。
由于存在α/β共格组织，使得本发明制备的氮化硅陶瓷能够承受宏观1-3％应变不产生断裂；当氮化硅的尺寸<1μm时，能够承受10-40％应变不产生断裂。
与现有技术相比，本发明制备的氮化硅陶瓷具有α/β共格组织，其突出优点为：
1.通过本发明所述方法制备得到的具有α/β共格组织的氮化硅陶瓷，第一性原理计算表明，相变过程需跨越3.57eV的能垒，表明在承受载荷的条件下，可以通过β相向α相的相变吸收能量，同时，由于α和β相间晶体结构的差异导致β相向α相转变后会产生体积变化，因此通过相变可以缓解在陶瓷内部的应力集中，使氮化硅陶瓷的性能得到提高；
2.通过本发明所述方法制备得到的具有α/β共格组织的氮化硅陶瓷，在承受载荷的条件下，可以通过β相向α相相变，相变过程中β晶粒尺寸不断减小，从而使得氮化硅陶瓷的晶粒尺寸不断减小，起到细晶强化的作用；
3.通过本发明所述方法制备得到的具有α/β共格组织的氮化硅陶瓷，在承受载荷的条件下，氮化硅内部通过共价键的断开、重组及转换，和原子振动、旋转等过程 实现了β相向α相的相变，该过程伴随着原子层间的切变，从而为陶瓷变形提供基础；
4.简单高效。本发明所述的氮化硅制备方法，制备过程简单高效。相比于传统制备氮化硅的工艺，本发明所述的烧结温度降低100-200℃，时间缩短5-10h。
5.低碳、生产效率高，适宜于大批量生产。
附图说明
图1是实施例1-3中所用氮化硅粉末原料的XRD分析图谱；
图2是实施例1中氮化硅陶瓷的XRD分析图谱；
图3是实施例1中氮化硅陶瓷的共格组织分布图；
图4是实施例1中氮化硅陶瓷产物的SEM分析图谱；
图5是实施例1中氮化硅陶瓷产物的应力应变曲线；
图6是实施例2中氮化硅陶瓷产物的XRD分析图谱；
图7是实施例2中氮化硅陶瓷产物的SEM分析图谱；
图8是实施例3中氮化硅陶瓷产物的XRD分析图谱；
图9是对比例1中氮化硅陶瓷产物的XRD分析图谱；
图10是实施例1和对比例1产物压缩对比图。
实施发明的最佳方式
以下将结合附图和实施例对本发明进一步说明。应当理解，下面实施例仅为示例性地说明和解释本发明，而不应被解释为对本发明保护范围的限制。凡基于本发明上述内容所实现的技术均涵盖在本发明旨在保护的范围内。
在本文中，所述氮化硅陶瓷的抗弯强度测试根据标准GB/T 6569-2006测试，硬度测试根据标准GB/T 16534-2009测试，断裂韧性测试根据标准GB/T 23806-2009测试。所述氮化硅陶瓷中，α相含量通过X射线衍射(XRD)测得；α/β共格组织含量通过旋进电子衍射(PED)或透射菊池衍射(TKD)测量得到。
下述实施例中，α相氮化硅粉的纯度>99wt％；所述α相氮化硅粉的平均粒径0.2-10μm；α相氮化硅粉中α相的纯度>90wt％。所使用的烧结助剂的纯度>99wt％，各烧结助剂的平均粒度为300-500nm。
实施例1、可变形氮化硅陶瓷的制备
(1)混料：将干燥后的陶瓷原料按比例混合均匀，过60目筛；
所述陶瓷原料，由下述质量百分含量的组分组成：
α相氮化硅粉：95％；
烧结助剂：5％；
所述烧结助剂，由下述质量百分含量的组分组成：
Al 2O 3：60％；
Y 2O 3：40％；
(2)研磨：将需混料的粉料置于砂磨机中，按粉料：乙醇＝1：2(w/w)加入粉料和乙醇，砂磨转速设置为3000r/min，砂磨2h。
(3)烧结：将砂磨所得粉料装入烧结模具后，再将模具装入快速热压烧结装置内，抽真空后，以3000℃/min的速度升温至1550℃，在30MPa压力下保温5min，停止加热后随炉冷却至室温。取出样品，所得氮化硅陶瓷的相对密度＝99.2％，α相含量＝49％，α/β共格组织含量为30％，断裂韧性＝10MPa·m 1/2，维氏硬度＝23.1Gpa，抗弯强度＝650MPa，对于尺寸<1μm的样品，最大可承受32％的应变不产生破坏。
图2-4为实施例1制备的氮化硅陶瓷的表征图。由图2可知，α相含量＝49％，由图3可知，α/β共格组织含量为30％，由图4可知，烧结后晶粒尺寸为200-500nm左右，与图3一致。
图5为实施例1制备的氮化硅陶瓷的应力应变曲线。由图可知，测试样品达到32％的最大应变，此时承受的应力可达10GPa。
实施例2、可变形氮化硅陶瓷的制备
(1)混料：将干燥后的陶瓷原料按比例混合均匀，过60目筛；
所述陶瓷原料，由下述质量百分含量的组分组成：
α相氮化硅粉：80％；
烧结助剂：20％；
所述烧结助剂，由下述质量百分含量的组分组成：
La 2O 3：80％；
MgO：20％；
(2)研磨：将需混料的粉料置于球磨机中，按粉料：乙醇＝1：2(w/w)加入粉料和乙醇，球磨转速设置为300r/min，研磨24h。
(3)烧结：将粉料装入烧结模具后，再将模具装入放电等离子体烧结装置内，抽真空后，以150℃/min的速度升温至1500℃，在30MPa压力下保温5min，停止加热后 随炉冷却至室温。取出样品，所得氮化硅陶瓷的相对密度＝99.1％，α相含量＝72％，α/β共格组织含量为25％，断裂韧性＝8MPa·m 1/2，维氏硬度＝19.2Gpa，抗弯强度＝687MPa，对于尺寸<1μm的样品，最大可承受25％的应变不产生破坏。
图6-7为实施例2制备的氮化硅陶瓷的表征图。α相含量＝72％，烧结后晶粒尺寸200-500nm左右。
实施例3、可变形氮化硅陶瓷的制备
(1)混料：将干燥后的陶瓷原料按比例混合均匀，过60目筛；
所述陶瓷原料，由下述质量百分含量的组分组成：
α相氮化硅粉：70％；
烧结助剂：20％；
相变抑制剂：10％；
所述相变抑制剂，由下述质量百分含量的组分组成：5％CaO+5％Lu 2O 3；
所述烧结助剂，由下述质量百分含量的组分组成：
Y 2O 3：50％；
SiO 2：50％；
(2)研磨：将需混料的粉料置于搅拌磨中，按粉料：乙醇＝1：2(w/w)加入粉料和乙醇，砂磨转速设置为500r/min，研磨12h。
(3)烧结：将粉料在20MPa压力下干压成型，然后200MPa冷等静压保压5min，将压型后的素坯置于氮化硼坩埚内，一起放入热等静压烧结炉中，在烧结炉中以10℃/min的速度升温至1600℃，保温4h，烧结在5MPa氮气气氛下进行，停止加热后随炉冷却至室温。取出样品，所得氮化硅陶瓷的相对密度＝99.3％，α相含量＝29％，α/β共格组织含量为20％，断裂韧性＝9MPa·m 1/2，维氏硬度＝18.7Gpa，抗弯强度＝860MPa，对于尺寸<1μm的样品，最大可承受17％的应变不产生破坏。
对比例1
(1)混料：将干燥后的陶瓷原料按比例混合均匀，过60目筛；
所述陶瓷原料，由下述质量百分含量的组分组成：
β相氮化硅粉：95％；
烧结助剂：5％；
所述烧结助剂，由下述质量百分含量的组分组成：
Al 2O 3：60％；
Y 2O 3：40％；
(2)研磨：将需混料的粉料置于砂磨机中，按粉料：乙醇＝1：2加入粉料和乙醇，砂磨转速设置为3000r/min，砂磨2h。
(3)烧结：将粉料装入烧结模具后，再将模具装入快速热压烧结装置内，抽真空后，以3000℃/min的速度升温至1700℃，在30MPa压力下保温5min，停止加热后随炉冷却至室温。取出样品，所得氮化硅陶瓷的相对密度＝99.2％，α相含量＝0％，α/β共格组织含量为0％，断裂韧性＝5MPa·m 1/2，维氏硬度＝16.3Gpa，抗弯强度＝650MPa，对于尺寸<1μm的样品，无法发生塑性应变，仅在弹性变形阶段就发生脆性断裂。
对比例2
(1)混料：将经过干燥后的陶瓷原料按比例混合均匀，过100目筛，所述陶瓷原料，由下述组分组成：
氮化硅粉：80％；
烧结助剂：15％；
相变抑制剂：5％；
所述烧结助剂，由下述组分组成：MgO：40％；Y 2O 3：40％；SiO 2：20％；
(2)研磨：将需混料的粉料置于球磨机中，按粉料：乙醇＝1：2加入粉料和乙醇，砂磨转速设置为300r/min，球磨10h。
(3)烧结：将粉料装入SPS模具中后将模具装入SPS装置内，抽真空后，以150℃/min的速度升温至1500℃，在50MPa压力下保温5min，停止加热后随炉冷却至室温。取出样品后，获得一次烧结体，所得一次烧结体的相对密度＝99.3％，α相含量＝90％。将其置于氮化硼坩埚后装入气压烧结炉中，以5℃/min的速度升温至1600℃，在6MPa的氮气压力下保温1h，随后迅速降温至900℃，与此同时，压力降至1MPa，然后以20℃/min的速度升温至1600℃，然后停止加热，随炉冷却至室温。
所得陶瓷的α相含量＝50％，相对密度＝99.4％，断裂韧性＝10.5MPa·m 1/2，维氏硬度＝19.3Gpa，抗弯强度＝745MPa。对于尺寸<1μm的样品，最大可承受8％的应变不产生破坏。
将实施例1的结果与对比例1的结果进行对比，实施例1与对比例1的试验条件基本相同，区别在于实施例1通过使用α相氮化硅粉作为原料，获得了α/β共格组织 含量为30％的氮化硅陶瓷，而对比例1中不具有α/β共格组织。从试验结果来看，最终烧结产品的断裂韧性由对比例1的5MPa·m 1/2提高到实施例1的10MPa·m 1/2，维氏硬度由对比例1的16.3Gpa提高到实施例1的23.1Gpa，特别的，对比例1并不具备承受应变能力，实施例1最大可以承受32％的应变不产生断裂。实施例1和对比例1产物压缩对比图如图10所示。由图可知，具备α/β共格组织的样品发生了明显的塑性变形，且在20％应变时仍然不破坏，不具备α/β共格组织的样品未发生塑性变形即发生了脆性断裂。可见，使用本发明所述制备工艺所制备的具有α/β共格组织的氮化硅陶瓷，能够大幅度提高氮化硅陶瓷的力学性能，基于该制备方法能够获得性能优异的氮化硅陶瓷。
工业应用
本发明制备得到的具有α/β共格组织的氮化硅陶瓷，在承受载荷的条件下，氮化硅内部通过共价键的断开、重组及转换，和原子振动、旋转等过程实现了β相向α相的相变，该过程伴随着原子层间的切变，从而为陶瓷变形提供基础。

Claims (15)

  1. 一种可变形氮化硅陶瓷的制备方法，包括下述步骤：
    1)将下述质量百分含量的组分混合均匀，得到混合物；
    α相氮化硅粉   70-98wt％，
    烧结助剂        2-30wt％，
    2)将步骤1)所得混合物进行烧结，得到具有α/β共格组织的可变形氮化硅陶瓷。
  2. 根据权利要求1所述的制备方法，其特征在于：所述步骤1)中，所述α相氮化硅粉的纯度>99wt％；所述α相氮化硅粉的平均粒径0.2-10μm，氮化硅粉中α相含量>90wt％。
  3. 根据权利要求1或2所述的制备方法，其特征在于：所述步骤1)中，所述烧结助剂选自Al 2O 3、MgO、SiO 2、Y 2O 3、ZrO 2、RE 2O 3、MgSiN 2中的一种或多种，其中RE代表稀土元素。
  4. 根据权利要求1-3中任一项所述的制备方法，其特征在于：所述烧结助剂的纯度>99wt％，所述烧结助剂的平均粒度为300-500nm。
  5. 根据权利要求1-4中任一项所述的制备方法，其特征在于：所述组分还包括相变抑制剂；所述相变抑制剂选用CaO、RE 2O 3中的一种或多种，其中RE代表稀土元素。
  6. 根据权利要求1-5中任一项所述的制备方法，其特征在于：所述混合物包括下述质量百分含量的组分：
    α相氮化硅粉   70-98wt％
    烧结助剂        2-30wt％
    相变抑制剂      0-10wt％。
  7. 根据权利要求1-6中任一项所述的制备方法，其特征在于：所述步骤1)中，所述的混合包括砂磨、球磨或搅拌磨；使用的介质选自水、甲醇、乙醇中的任一种；所述砂磨的磨球选自氮化硅磨球、氧化锆磨球、玛瑙磨球中的一种，其中磨球尺寸<1mm；所述球磨的磨球为氮化硅磨球，磨球尺寸为3-10mm；所述搅拌磨的磨球为氮化硅磨球，磨球尺寸为3-10mm。
  8. 根据权利要求1-7中任一项所述的制备方法，其特征在于：所述步骤1)中，所述的混合，其转速为300-3000r/min，混料时间为2-24h。
  9. 根据权利要求1-8中任一项所述的制备方法，其特征在于：所述步骤2)中，所述的烧结方法选自下述一种或多种烧结方法：快速热压烧结、放电等离子体烧结、热压烧结、热等静压烧结、气压烧结或震荡压力烧结。
  10. 根据权利要求9所述的制备方法，其特征在于：所述的烧结方法为快速热压烧结法，具体制备方法为：先将步骤(1)所得混合物干燥，过60-200目筛，装料于烧结模具内，再将所述模具放置在快速热压烧结装置内，抽真空后，对原料加压，同时通电加热进行烧结，快速热压烧结的升温速率为1000-5000℃/min；反应烧结结束后，样品随炉进行冷却，冷却后得到烧结产物；所述烧结的压力范围为10-100MPa，烧结温度为1500-1800℃，保温时间为1-5min。
  11. 根据权利要求9所述的制备方法，其特征在于：所述的烧结方法为放电等离子体烧结法，具体制备方法为：先将步骤(1)所得混合物干燥，过60-200目筛，装料于烧结模具内，再将所述模具装入放电等离子体烧结装置内，抽真空后，对原料加压，同时通电加热进行烧结，放电等离子体烧结升温速率为150-200℃/min；反应烧结结束后，样品随炉进行冷却，冷却后得到烧结产物；所述烧结的压力范围为10-100MPa，烧结温度为1500-1800℃，保温时间为1-5min。
  12. 根据权利要求9所述的制备方法，其特征在于：所述的烧结方法为热等静压烧结法，具体制备方法为：先将步骤(1)所得混合物干燥，过60-200目筛，然后将混合粉末进行干压成型，压力为1-50MPa，保压1-5min，再将干压成型的素坯进行冷等静压，压力为200-800MPa，保压1-5mim，然后将所得物置于氮化硼坩埚内，一起放入热等静压烧结炉中，在烧结炉中以5-20℃/min的速度升温至1500-1800℃，保温0.5-8h；所述热等静压烧结的压力为0-500MPa。
  13. 权利要求1-12中任一项所述方法制备得到的可变形氮化硅陶瓷。
  14. 根据权利要求13所述的可变形氮化硅陶瓷，其特征在于：所述可变形氮化硅陶瓷的相对密度>99％，断裂韧性>8MPa·m 1/2，维氏硬度>17Gpa，抗弯强度>600MPa。
  15. 根据权利要求13或14所述的可变形氮化硅陶瓷，其特征在于：所述可变形氮化硅陶瓷含有α/β共格组织，所述α/β共格组织的含量为10-70％。
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Publication number Priority date Publication date Assignee Title
WO2011102298A1 (ja) * 2010-02-16 2011-08-25 株式会社東芝 耐摩耗性部材およびその製造方法
CN103011872A (zh) * 2012-11-28 2013-04-03 大连大友高技术陶瓷有限公司 一种氮化硅增韧陶瓷的制备方法
CN103848639A (zh) * 2012-11-28 2014-06-11 大连大友高技术陶瓷有限公司 一种氮化硅增韧陶瓷
CN110818428A (zh) * 2019-12-03 2020-02-21 清华大学 一种共晶增强增韧氮化硅陶瓷的制备方法

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2011102298A1 (ja) * 2010-02-16 2011-08-25 株式会社東芝 耐摩耗性部材およびその製造方法
CN103011872A (zh) * 2012-11-28 2013-04-03 大连大友高技术陶瓷有限公司 一种氮化硅增韧陶瓷的制备方法
CN103848639A (zh) * 2012-11-28 2014-06-11 大连大友高技术陶瓷有限公司 一种氮化硅增韧陶瓷
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