CN111592360A

CN111592360A - Polycrystal B4C-diamond double-layer composite material and preparation method thereof

Info

Publication number: CN111592360A
Application number: CN202010516995.2A
Authority: CN
Inventors: 欧阳晓平; 王海阔; 欧阳潇; 谈仲军
Original assignee: Individual
Current assignee: Individual
Priority date: 2020-06-09
Filing date: 2020-06-09
Publication date: 2020-08-28

Abstract

The invention discloses a polycrystal B₄A C-diamond double-layer composite material and a preparation method thereof belong to the field of inorganic nonmetallic materials, and the method uses B₄Purifying the raw materials, pre-pressing to form, wrapping the pre-pressed raw materials with metal wrap, assembling high-pressure assembly unit, placing in high-pressure equipment, sintering at high temperature and high pressure to obtain polycrystal B₄C-diamond double layer composite; the polycrystal B₄The C-diamond double-layer composite material has polycrystalDiamond and polycrystal B₄C double layer structure, diamond layer and B₄The C layer is sintered and compounded together at high temperature and high pressure, the two layers of polycrystalline materials are tightly combined, the grain size distribution is uniform, the density is high, the characteristics of high hardness and high fracture toughness of diamond are achieved, and the B layer is combined₄Easy sintering of C and low density.

Description

Polycrystal B4C-diamond double-layer composite material and preparation method thereof

Technical Field

The invention relates to a polycrystal B₄A C-diamond double-layer composite material and a preparation method thereof belong to the field of inorganic non-metallic 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 B₄The C has the characteristics of low density, high strength and good chemical stability, and is used in wear-resistant materials and 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 low fracture toughness and poor high-temperature stability (basically stable at the temperature of below 800 ℃ in an air environment, and can be oxidized at a 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.

Diamond is the hardest known substance in nature, has extremely high wear resistance, compressive strength and heat dissipation rate, and is a super-hard material widely applied in the industry at present; the diamond single crystal is expensive and has a dissociation surface, and polycrystalline diamond materials with higher use price ratio are used for replacing the diamond single crystal in many fields in the industry; the traditional polycrystalline sintered body of the artificial diamond is a composite polycrystalline superhard material which is formed by uniformly mixing artificial diamond powder with metal powder such as Co, Ni and the like and then sintering the mixture at high pressure and high temperature, shows isotropy and higher hardness and toughness macroscopically, has better application performance in certain aspects than single crystals, is widely applied to the cutting processing of nonferrous metals, non-ferrous alloys and ceramic materials, the fields of petroleum, natural gas and mining industry exploration, wood floor processing and the like, but the diamond powder for preparing the polycrystalline diamond is expensive, and limits the large-scale application of the polycrystalline diamond to a certain extent.

The composite material is prepared by optimally combining material components with different properties by using an advanced material preparation technologyThe composite material has two or more material components with different chemical and physical properties, and obvious interfaces exist among the components; the composite material has structural designability and can be used for designing a composite structure; 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 with polycrystalline diamond to obtain polycrystalline B₄The C-diamond double-layer composite material not only has the characteristics of high hardness and high fracture toughness of diamond, but also has the characteristic of B₄C has the advantages of low cost, low density and easy sintering, but the preparation of polycrystal B does not appear at present₄C-report of diamond bilayer composite.

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 and diamond powder at high temperature and high pressure₄C-method of diamond 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-diamond double-layer composite material comprises the following steps:

a. raw material treatment: respectively treating diamond 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 diamond powder and 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: putting the high-pressure sintering unit into a synthesis cavity of high-pressure equipment, starting boosting, raising the temperature and heating after the set pressure is reached, and keeping the temperature for a period of time; after the heat preservation is finished, stopping heating, maintaining the pressure for a period of time, and then slowly reducing the pressure;

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-diamond double-layer composite material.

Preferably, the diamond powder raw material with the grain size of 3 nm-500 mu m is added with a sintering aid A, and the B4C polycrystalline block with the grain size of 3 nm-500 mu m or the powder raw material is added with a sintering aid B.

Preferably, the sintering aid A is one or more of Co, Ni, Si and Fe, and the sintering aid B is one or more of Si, B 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 and high-pressure sintering are that the sintering pressure is 1-5GPa, the sintering temperature is 600-1250 ℃, and the heat preservation time is 20 seconds-5 minutes.

Preferably, the resulting polycrystal B is prepared₄The thickness of the C-diamond 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 diamond 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, the main phase of polycrystalline diamond layer is diamond, and polycrystalline B₄The main phase of the C layer is B₄And C, the two layers of polycrystalline materials are tightly combined, the relative density is high, the porosity is low, the crystal grain size is uniformly distributed, and the high-temperature stability and the good mechanical property are realized. Such as poly-crystal B₄The high temperature stability of the C layer is 810-Vickers hardness of 60-90 GPa, and polycrystal B₄Hardness of the C layer is 30-40 GPa), and high toughness (fracture toughness of the polycrystalline diamond layer is 7.5-13 MPa.m)^1/2Of the polycrystal B₄The fracture toughness of the C layer is 3.5-6.5 MPa.m^1/2) And the like, not only has the characteristics of high hardness and high fracture toughness of diamond, but also combines B₄C has the advantages of low cost, low density and easy sintering, and has wide application prospect;

2. the invention utilizes the conditions of high temperature and high pressure to prepare the polycrystal B₄The C-diamond double-layer composite material can inhibit the abnormal growth of crystal grains under the high-temperature condition under the high pressure, and successfully solves the problem that B is abnormal₄C, abnormal growth of crystal grains in the high-temperature normal-pressure sintering process;

3. the invention can utilize a domestic cubic press to prepare the polycrystal B₄The C-diamond 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 B₄C-scanning electron microscope analysis chart of the diamond double-layer composite material;

FIG. 3 shows example 1 polycrystal B₄Polycrystal B of C-diamond double-layer composite material₄C layer scanning electron microscope analysis chart;

FIG. 4 shows example 1 polycrystal B₄C, scanning electron microscope analysis chart of the polycrystalline diamond layer of the diamond double-layer composite material;

FIG. 5 example 2 polycrystal B₄C-scanning electron microscope analysis chart of the diamond double-layer composite material;

FIG. 6 example 2 polycrystal B₄Polycrystal B of C-diamond double-layer composite material₄C layer scanning electron microscope analysis chart;

FIG. 7 example 2 polycrystal B₄C, scanning electron microscope analysis chart of the polycrystalline diamond layer of the diamond double-layer composite material;

FIG. 8 example 3 polycrystal B₄C-scanning electron microscope analysis chart of the diamond double-layer composite material;

FIG. 9 example 3 polycrystal B₄C-diamond double-layer compositePoly crystal B of material₄C layer scanning electron microscope analysis chart;

FIG. 10 shows example 3 polycrystal B₄And C, scanning electron microscope analysis chart of the polycrystalline diamond layer of the diamond double-layer composite material.

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.

Example 1:

a. raw material treatment and detection: taking polycrystal B with purity of 98% and average grain size of 10 μm₄30 g of C block material; taking 27 g of diamond powder with the purity of 98 percent and the average grain size of 8 mu m, adding 6 percent of Si powder in volume fraction into the diamond powder as a sintering aid, treating the diamond powder by using 50 ml of absolute ethyl alcohol, pouring out waste liquid, and drying the diamond powder in an oven at 120 ℃; polycrystal B₄Adding Si with the volume fraction of 2% into the C block as a sintering aid, treating with 60 ml of absolute ethyl alcohol, pouring out waste liquid, drying in an oven at 120 ℃, and obtaining the dried polycrystal B₄Respectively adding 50 ml of deionized water into the C block and the diamond powder, respectively prepressing and forming, and drying a formed sample in a vacuum drying oven;

b. assembling a sintering unit: processing the metal inclusion for wrapping the raw material, grinding and polishing, then removing oil, ultrasonic cleaning, vacuum drying, and mixing the diamond powder layer formed by pre-pressing with the diamond powder layer B₄C, sticking the block material layers together and wrapping the block material layers by using a metal wrapping body to prevent the sample from being polluted in a high-temperature and high-pressure environment; loading the wrapped sample into a high-pressure assembly sintering unit, and drying the assembled sintering unit in a drying oven at a constant temperature of 120 ℃ for later use;

c. high-temperature high-pressure sintering: sintering at high temperature and high pressure by using a cubic press, heating after reaching the set pressure of 5GPa, preserving the heat at 1450 ℃ for 10 minutes, stopping heating after finishing preserving the heat, maintaining the pressure for 2 minutes, and then slowly reducing the pressure;

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

And (3) detecting the performance of the sample: preparation of the resulting polycrystal B₄The thickness of the C-diamond double-layer composite material is 6mm, wherein the polycrystal B₄The thickness of the C layer is 3 mm, the thickness of the polycrystalline diamond is 3 mm, the sample phase composition is detected by XRD, the main phase of the polycrystalline diamond layer is diamond, and the polycrystalline B layer is₄The main phase of the C layer is B₄C; the microscopic morphology of the sample is detected by SEM, the sample has high density and low porosity; the Vickers hardness test shows that the Vickers hardness of the polycrystalline diamond layer is 70 GPa, and the polycrystal B₄The hardness of the C layer was 35 GPa, and the fracture toughness of the polycrystalline diamond layer was 9.5 MPa m^1/2Of the polycrystal B₄The fracture toughness of the C layer is 4.5 MPa-m^1/2Detecting B by differential thermal analysis₄The high temperature stability of layer C was 840 ℃.

Example 2:

a. raw material treatment and detection: taking polycrystal B with purity of 99% and average grain size of 2 μm₄55g of C block, namely 56 g of diamond powder with the purity of 99% and the average grain size of 25 mu m, adding 2% by volume of Co powder into the diamond powder as a sintering aid, treating the mixture by using 100 ml of absolute ethyl alcohol, pouring out waste liquid, and drying the waste liquid in an oven at 120 ℃; polycrystal B₄Treating the C blocks with 90 ml of absolute ethyl alcohol, pouring out waste liquid, drying at 120 ℃ in an oven, and drying to obtain the polycrystal B₄Respectively adding 95 ml of deionized water into the C block and the diamond powder, respectively prepressing and forming, and drying a formed sample in a vacuum drying oven;

b. this step is the same as step b in example 1;

c. high-temperature high-pressure sintering: sintering at high temperature and high pressure by using a cubic press, heating after the set pressure is 7 GPa, preserving the heat for 15 minutes at 1250 ℃, stopping heating after the heat preservation is finished, maintaining the pressure for 2 minutes, and then slowly reducing the pressure;

d. this step is the same as step d in example 1.

And (3) detecting the performance of the sample: preparation of the resulting polycrystal B₄The thickness of the C-diamond double-layer composite material is 10 mm, wherein the polycrystal B₄The thickness of the C layer is 5 mm, the thickness of the polycrystalline diamond is 5 mm, the XRD is utilized to detect the composition of the sample phase, the main phase of the polycrystalline diamond layer is diamond, and the polycrystalline B layer is₄The main phase of the C layer is B₄C; the microscopic morphology of the sample is detected by SEM, the sample has high density and low porosity; the Vickers hardness test shows that the Vickers hardness of the polycrystalline diamond layer is 65 GPa, and the polycrystal B₄The hardness of the C layer is 37 GPa, and the fracture toughness of the polycrystalline diamond layer is 10 MPa-m^1/2Of the polycrystal B₄The fracture toughness of the C layer is 4.4 MPa.m^1/2Detecting B by differential thermal analysis₄The high temperature stability of the C layer was 880 DEG C

Example 3:

a. raw material treatment and detection: taking polycrystal B with the purity of 98% and the average grain size of 500 nm₄85 g of block C, taking 66 g of diamond powder with the purity of 99% and the average grain size of 15 mu m, treating the diamond powder with 120 ml of absolute ethyl alcohol, pouring out waste liquid, drying at 120 ℃ in an oven, and obtaining polycrystal B₄Treating the C blocks with 140 ml of absolute ethyl alcohol, pouring out waste liquid, drying at 120 ℃ in an oven, and drying to obtain the polycrystal B₄Respectively adding 70 ml of deionized water into the C block and the diamond powder, respectively prepressing and forming, and drying a formed sample in a vacuum drying oven;

b. this step is the same as step b in example 1;

c. high-temperature high-pressure sintering: sintering at high temperature and high pressure by using a cubic press, heating after the set pressure reaches 10 GPa, preserving the heat for 5 minutes at 1500 ℃, stopping heating after the heat preservation is finished, maintaining the pressure for 2 minutes, and then slowly reducing the pressure;

d. this step is the same as step d in example 1.

And (3) detecting the performance of the sample: preparation of the resulting polycrystal B₄The thickness of the C-diamond double-layer composite material is 14 mm, wherein the polycrystal B₄The thickness of the C layer is 8 mm, the thickness of the polycrystalline diamond is 6mm, and the sample is detected by XRDThe main phase of the polycrystalline diamond layer is diamond and the polycrystal B₄The main phase of the C layer is B₄C; the SEM detects the microscopic morphology of the sample, the combination is tight, the sample density is high, and the porosity is low; the Vickers hardness test shows that the Vickers hardness of the polycrystalline diamond layer is 74 GPa, and the polycrystalline B₄The hardness of the C layer was 40GPa, and the fracture toughness of the polycrystalline diamond layer was 11.4 MPa-m^1/2Of the polycrystal B₄The fracture toughness of the C layer is 6 MPa m^1/2Detecting B by differential thermal analysis₄The high temperature stability of layer C was 910 ℃.

Claims

1. Polycrystal B₄The preparation method of the C-diamond double-layer composite material is characterized in that B is used₄C, sintering the polycrystalline block or powder and the diamond powder serving as raw materials under the conditions of high temperature and high pressure, and specifically comprising the following steps:

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-diamondA stone double-layer composite material.

2. The method of claim 1, wherein: the diamond powder raw material with the grain size of 3 nm-500 mu m is added with a sintering aid A and a sintering aid 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.

3. The method of claim 2, wherein: the sintering aid A is one or more of Co, Ni, Si and Fe, 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 1-5GPa, the sintering temperature is 600-1250 ℃, and the heat preservation time is 20 seconds-5 minutes.

6. The method of claim 1, wherein: preparation of the resulting polycrystal B₄The thickness of the C-diamond 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 diamond is 1-199 mm.

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

8. Polycrystal B₄A C-diamond two-layer composite material characterized by being produced by the production method according to any one of claims 1 to 7.