阅读说明：本技术 一种多晶B4C—SiC双层复合材料及其制备方法 (Polycrystal B4C-SiC double-layer composite material and preparation method thereof ) 是由 欧阳晓平 王海阔 欧阳潇 谈仲军 于 2020-06-09 设计创作，主要内容包括：本发明涉及一种多晶B<Sub>4</Sub>C—SiC双层复合材料及其制备方法,属于无机非金属材料领域,该方法以B<Sub>4</Sub>C多晶块体或粉末、SiC多晶块体或粉末为原料,通过对原料进行净化处理,预压成型,预压成型的原料用金属包裹体包裹,装配高压组装单元,放置于超高压设备中,在600-2300℃,1-25 GPa高温高压条件下烧结,制得多晶B<Sub>4</Sub>C—SiC双层复合材料；利用本发明制备的多晶B<Sub>4</Sub>C—SiC双层复合材料具有多晶SiC与多晶B<Sub>4</Sub>C双层结构,SiC层与B<Sub>4</Sub>C层经高温高压烧结在一起,两层多晶体结合紧密,晶粒大小分布均匀,致密度高；该多晶B<Sub>4</Sub>C—SiC双层复合材料既具备B<Sub>4</Sub>C较高硬度、较高断裂韧性、密度小的特点,又结合了SiC成本低、易烧结的优点。(The invention relates to a polycrystal B 4 A C-SiC double-layer composite material and a preparation method thereof belong to the field of inorganic nonmetallic materials, and the method uses B 4 The polycrystalline B is prepared by using polycrystalline C blocks or powder and polycrystalline SiC blocks or powder as raw materials, purifying the raw materials, performing pre-pressing molding, wrapping the pre-pressed raw materials with a metal wrapping body, assembling a high-pressure assembly unit, placing the assembly unit in ultrahigh-pressure equipment, and sintering at 600 plus 2300 ℃ under the high-temperature and high-pressure conditions of 1-25GPa 4 C-SiC double layer composites; polycrystal B produced by the present invention 4 The C-SiC double-layer composite material has polycrystalline SiC and polycrystalline B 4 C double layer structure, SiC layer and B 4 High temperature of C layerThe two layers of polycrystal are tightly combined, the grain size distribution is uniform, and the density is high; the polycrystal B 4 The C-SiC double-layer composite material not only has B 4 C has the characteristics of higher hardness, higher fracture toughness and small density, and combines the advantages of low cost and easy sintering of SiC.)

1. Polycrystal B₄The preparation method of the C-SiC double-layer composite material is characterized by comprising the following steps: with B₄C polycrystal block or powder and SiC polycrystal block or powder are used as raw materials and sintered under the conditions of high temperature and high pressure, and the method specifically comprises the following steps:

a. raw material treatment: respectively treating SiC polycrystal block or powder with grain size of 3 nm-500 μm and B with grain size of 3 nm-500 μm with anhydrous ethanol₄C, polycrystalline blocks or powder, and drying the waste liquid at the temperature of 100-120 ℃ after pouring out the waste liquid; dried SiC polycrystalline block or powder, B₄C, respectively adding a proper amount of deionized water into the polycrystalline blocks or powder, respectively performing pre-pressing forming, and putting formed samples into a vacuum drying oven for vacuum drying;

b. assembling a sintering unit: wrapping the pre-pressed raw materials by using a metal wrapping body to avoid the pollution of a sample at high temperature and high pressure; loading the raw material with the metal inclusion into a high-pressure sintering unit, and placing the assembled high-pressure sintering unit into a drying box for constant-temperature drying for later use;

c. high-temperature high-pressure sintering: high-temperature and high-pressure sintering is carried out by utilizing high-pressure equipment, after the set pressure is reached, the temperature is raised and heated, the temperature is preserved for a period of time, after the temperature is preserved, the heating is stopped, and after the pressure is preserved for a period of time, the pressure is slowly reduced;

d. sample treatment: taking out the sample in the synthesis cavity, removing the metal inclusion wrapped outside the sample, and grinding, polishing and pickling the internal sample to obtain the polycrystal B₄C-SiC double-layer composite material.

2. The method of claim 1, wherein: the SiC polycrystal block or powder raw material with the grain size of 3 nm-500 mu m is added with a sintering aid A, and the SiC polycrystal block or powder raw material with the grain size of 3 nm-500 mu m is added with a sintering aid B₄And C, adding a sintering aid B into the polycrystalline block or powder raw material.

3. The method of claim 2, wherein: the sintering aid A is one or a mixture of Fe and Si, and the sintering aid B is one or more of B, Si and graphite.

4. The method of claim 1, wherein: the conditions of high-temperature and high-pressure sintering are that the sintering pressure is 1-25GPa, the sintering temperature is 600-2300 ℃, and the heat preservation time is 20 seconds-5 hours.

5. The method of claim 4, wherein: the conditions of high-temperature and high-pressure sintering are that the sintering pressure is 1-4GPa, the sintering temperature is 600-1300 ℃, and the heat preservation time is 20 seconds-15 minutes.

6. The method of claim 1, wherein: preparation of the resulting polycrystal B₄The thickness of the C-SiC double-layer composite material is 2-200 mm, wherein the polycrystal B₄The thickness of the C layer is 1-199mm, and the thickness of the polycrystalline SiC layer is 1-199 mm.

7. The method of claim 1, wherein: the high-pressure equipment is a domestic cubic press.

8. Polycrystal B₄A C-SiC bilayer composite material produced by the production method according to any one of claims 1 to 7.

Technical Field

The invention relates to a polycrystal B₄C-SiC double-layer composite material and preparation thereofThe preparation method belongs to the field of inorganic nonmetallic materials.

Technical Field

Boron carbide has the molecular formula of B₄C, a grey-black micropowder, is one of the three most known materials (the other two are diamond and cubic boron nitride), and B₄C has the characteristics of high hardness, high fracture toughness, low density and good chemical stability, and is used in the aspects of wear-resistant materials, ceramic reinforced phases, particularly light armors, reactor neutron absorbers and the like; in addition, compared with diamond and cubic boron nitride, the boron carbide is easy to manufacture and relatively low in cost, so that the boron carbide is widely used, and can replace expensive diamond in grinding, drilling and other aspects in some places; however, B₄The C block material as a structural material has poor high-temperature stability (basically stable at the temperature below 800 ℃ in the air environment, and can be oxidized at higher temperature to form boron oxide which flows off in a gas phase to cause instability), and limits the B block material to a certain extent₄And C, large-scale application.

The silicon carbide (alpha-SiC) ceramic has good chemical corrosion resistance, good wear resistance, small friction coefficient and high temperature resistance, and is an important ceramic material; silicon carbide has four major application areas: 1. abrasive and cutting tool: silicon carbide is used as a common abrasive in modern industrial processes due to its durability and low cost; 2. structural material: silicon carbide has the potential to be used as a structural material to replace nickel high-temperature alloy to manufacture turbine blades or nozzle blades; 3. astronomy, the silicon carbide can be used as a mirror material of an astronomical telescope; 4. the catalyst carrier is the carrier of the heterogeneous catalyst, which can be used by the silicon carbide due to the oxidation resistance; the silicon carbide has high yield, easy sintering and low production cost, but the polycrystalline silicon carbide block material has low fracture toughness when being used as a structural material, thereby limiting the application of the silicon carbide as the structural material to a certain extent.

The composite material is a new material formed by optimally combining material components with different properties by using an advanced material preparation technology, and has two or more material components with different chemical and physical properties, and obvious interfaces exist among the components; composite material toolThe structure is designable, and a composite structure can be designed; the composite material not only keeps the advantages of the properties of the materials of all the components, but also can obtain the comprehensive properties which cannot be achieved by a single composition material through the complementation and the correlation of the properties of all the components; if the polycrystal B is to be₄Compounding C and polycrystalline SiC to obtain polycrystalline B₄The C-SiC double-layer composite material not only can be provided with B₄C has the characteristics of high hardness, high fracture toughness and small density, and has the advantages of low cost and easy sintering of SiC, but the preparation of polycrystalline B does not appear at present₄C-SiC bilayer composite materials are reported.

Disclosure of Invention

The invention aims to overcome the defects in the prior art and provides a novel utilization B₄Preparing polycrystal B from polycrystal block or powder of C and polycrystal block or powder of SiC as raw materials under high-temperature and high-pressure conditions₄A method for preparing C-SiC double-layer composite material.

In order to achieve the purpose, the invention adopts the technical scheme that the polycrystal B₄The preparation method of the C-SiC double-layer composite material specifically comprises the following steps:

a. raw material treatment: respectively treating SiC polycrystal block or powder with grain size of 3 nm-500 μm and B with grain size of 3 nm-500 μm with anhydrous ethanol₄C, polycrystalline blocks or powder, and drying the waste liquid at the temperature of 100-120 ℃ after pouring out the waste liquid; dried SiC polycrystalline block or powder, B₄C, respectively adding a proper amount of deionized water into the polycrystalline blocks or powder, respectively performing pre-pressing forming, and putting formed samples into a vacuum drying oven for vacuum drying;

b. assembling a sintering unit: wrapping the pre-pressed raw materials by using a metal wrapping body to avoid the pollution of a sample at high temperature and high pressure; loading the raw material with the metal inclusion into a high-pressure sintering unit, and placing the assembled high-pressure sintering unit into a drying box for constant-temperature drying for later use;

c. high-temperature high-pressure sintering: high-temperature and high-pressure sintering is carried out by utilizing high-pressure equipment, after the set pressure is reached, the temperature is raised and heated, the temperature is preserved for a period of time, after the temperature is preserved, the heating is stopped, and after the pressure is preserved for a period of time, the pressure is slowly reduced;

d. sample treatment: taking out the sample in the synthesis cavity, removing the metal inclusion wrapped outside the sample, and grinding, polishing and pickling the internal sample to obtain the polycrystal B₄C-SiC double-layer composite material.

Preferably, the SiC polycrystalline block or powder raw material with the grain size of 3 nm-500 mu m is added with a sintering aid A and B with the grain size of 3 nm-500 mu m₄And C, adding a sintering aid B into the polycrystalline block or powder raw material.

Preferably, the sintering aid A is one or a mixture of Fe and Si, and the sintering aid B is one or more of B, Si and graphite.

Preferably, the conditions of the high-temperature and high-pressure sintering are that the sintering pressure is 1-25GPa, the sintering temperature is 600-2300 ℃, and the heat preservation time is 20 seconds-5 hours.

Preferably, the conditions of the high-temperature high-pressure sintering are that the sintering pressure is 1-4GPa, the sintering temperature is 600-1300 ℃, and the heat preservation time is 20 seconds-15 minutes.

Preferably, the resulting polycrystal B is prepared₄The thickness of the C-SiC double-layer composite material is 2-200 mm, wherein the polycrystal B₄The thickness of the C layer is 1-199mm, and the thickness of the polycrystalline SiC layer is 1-199 mm.

Preferably, the high-pressure equipment is a domestic cubic press.

The invention has the following beneficial effects:

1. polycrystal B produced by the present invention₄C-diamond double-layer composite material having polycrystalline diamond and polycrystalline B₄C double layer structure, polycrystal B₄The main phase of C is B₄C, the main phase of the polycrystalline SiC layer is α -SiC, the two layers of polycrystalline materials are tightly combined, the relative density is high, the porosity is low, the grain size is uniformly distributed, and the polycrystalline SiC layer has high-temperature stability and good mechanical properties, such as the polycrystalline B₄The high temperature stability of the C layer is 840-950 ℃, and the hardness is high (polycrystal B)₄The Vickers hardness of the C layer is 25-37 GPa, the hardness of the polycrystalline SiC layer is 18-28 GPa), and high toughness (the fracture toughness of the polycrystalline SiC layer is 2-4 MPa.m)^1/2Of the polycrystal B₄The fracture toughness of the C layer is 3-6 MPa.m^1/2) And the like,not only has B₄C has the characteristics of high hardness and high fracture toughness, combines the advantages of low cost and easy sintering of SiC, and has wide application prospect;

2. the invention utilizes the conditions of high temperature and high pressure to prepare the polycrystal B₄The C-SiC double-layer composite material can inhibit abnormal growth of crystal grains under high temperature condition under high pressure, and successfully solves the problem of B₄C. The abnormal growth of crystal grains of SiC in the high-temperature normal-pressure sintering process;

3. the invention can utilize a domestic cubic press to prepare the polycrystal B₄The C-SiC double-layer composite material can realize large-scale industrial production and reduce the production cost.

Drawings

FIG. 1 is a process flow diagram of the present invention;

FIG. 2 shows example 1 polycrystal B₄A scanning electron microscope analysis chart of the C-SiC double-layer composite material;

FIG. 3 shows example 1 polycrystal B₄A scanning electron microscope analysis chart of the polycrystalline SiC layer of the C-SiC double-layer composite material;

FIG. 4 shows example 1 polycrystal B₄Polycrystal B of C-SiC double-layer composite material₄C layer scanning electron microscope analysis chart;

FIG. 5 example 2 polycrystal B₄A scanning electron microscope analysis chart of the C-SiC double-layer composite material;

FIG. 6 example 2 polycrystal B₄A scanning electron microscope analysis chart of the polycrystalline SiC layer of the C-SiC double-layer composite material;

FIG. 7 example 2 polycrystal B₄Polycrystal B of C-SiC double-layer composite material₄C layer scanning electron microscope analysis chart;

FIG. 8 example 3 polycrystal B₄A scanning electron microscope analysis chart of the C-SiC double-layer composite material;

FIG. 9 example 3 polycrystal B₄A scanning electron microscope analysis chart of the polycrystalline SiC layer of the C-SiC double-layer composite material;

FIG. 10 shows example 3 polycrystal B₄Polycrystal B of C-SiC double-layer composite material₄C layer scanning electron microscope analysis chart.

Detailed Description

The present invention is further illustrated by the accompanying drawings and detailed description of embodiments thereof, it is to be noted that the present embodiments are further illustrative of the present invention and are not to be construed as limiting the scope of the invention, which is defined by the appended claims, and that insubstantial modifications and variations thereof can be made by those skilled in the art in light of the above teachings.