CN114573351B

CN114573351B - Boron carbide-based composite material and preparation method thereof

Info

Publication number: CN114573351B
Application number: CN202011390268.2A
Authority: CN
Inventors: 黄毅华; 刘营营; 黄政仁; 马宁宁; 葛盛
Original assignee: Shanghai Institute of Ceramics of CAS
Current assignee: Shanghai Institute of Ceramics of CAS
Priority date: 2020-12-02
Filing date: 2020-12-02
Publication date: 2023-05-09
Anticipated expiration: 2040-12-02
Also published as: CN114573351A

Abstract

The invention relates to a boron carbide-based composite material and a preparation method thereof, wherein the boron carbide-based composite material is obtained by taking at least one of molybdenum and tungsten as a toughening phase and boron carbide, titanium boride and silicon carbide as raw materials and performing hot press sintering or spark plasma sintering; the total volume content of the boron carbide, the titanium boride and the silicon carbide is 100vol%, the volume content of the boron carbide is 50-80 vol%, the volume content of the titanium boride is 10-25 vol%, and the volume content of the silicon carbide is 10-25 vol%; the volume content of the toughening phase is 1-20% of the total volume of boron carbide, titanium boride and silicon carbide.

Description

Boron carbide-based composite material and preparation method thereof

Technical Field

The invention relates to a boron carbide-based composite material and a preparation method thereof, in particular to a boron carbide-titanium boride-silicon carbide composite material containing a metal toughening phase and a preparation method thereof, belonging to the technical field of ceramic-based composite materials.

Background

Boron carbide ceramics have a range of excellent properties such as low density (2.52 g/cm ³ 1/3 of steel) and high hardness (inferior to diamond and cubic boron nitride), and at the same time, its elastic modulus is high, about 450GPa, melting point is up to 2450 deg.C, chemical stability is good, acid and alkali corrosion resistance is good, and at the same time, it also has good neutron absorption capability, which other ceramic materials do not possess. Due to the excellent properties, the boron carbide ceramic can be applied to the field of wear resistance, such as grinding tools and knivesA tool; ballistic armor fields, such as fuselage ballistic protection and body protection; neutron absorption fields, such as nuclear reactor shielding materials; other fields, such as flow transmitters, gas bearing materials, thermocouples, etc. that can be used in rocket liquid engines. However, the existence of strong covalent bonds between B and C and surface oxides leads to high densification temperature of the boron carbide ceramic, further leading to growth of crystal grains and deterioration of mechanical properties, and low fracture toughness value of the boron carbide, which is only 2-3 MPa.m ^1/2 Greatly limiting the wide application of boron carbide ceramics.

Ballistic armor materials offer penetration resistance, impact resistance, and collapse resistance to their ballistic performance, which in turn puts forward requirements on high hardness and modulus of elasticity, toughness, and strength. The boron carbide ceramic becomes a very promising bulletproof armor material with extremely low density and extremely high hardness, so the boron carbide ceramic has great significance for toughening the boron carbide ceramic. At present, the research on boron carbide ceramics is mainly focused on preparing compact boron carbide ceramics at low temperature and realizing toughening. At present, the toughening of the ceramic material mainly comprises the composite toughening of ceramic and metal, the phase change toughening, the micro-crack toughening, the surface toughening, the toughening by adding reinforcing fibers or whiskers and the toughening by controlling the organization forming process of the ceramic.

The titanium boride material has high hardness and lower density, and the thermal expansion coefficient is not matched with that of boron carbide, so that residual thermal stress can be generated, the grain boundary of the titanium boride material and the boron carbide is weakened, crack deflection or bridging is further realized, and the effect of toughening the boron carbide is finally achieved. Chinese patent No. 1 (publication No. CN108484171 a) prepared a boron carbide-titanium boride composite ceramic by pressureless sintering, and improved the fracture toughness of boron carbide. Chinese patent 2 (publication No. CN111116202 a) prepared boron carbide-titanium boride composite ceramic by spark plasma reaction sintering of amorphous boron powder, titanium powder, and graphite powder.

Silicon carbide is used as a structural ceramic material, and has the advantages of high hardness, low density, high melting point, good chemical stability and capability of improving the fracture toughness of boron carbide ceramic by introducing the silicon carbide. Chinese patent 3 (publication No. CN108640687 a) prepares a boron carbide-silicon carbide composite ceramic with excellent performance by pressureless sintering. However, the toughness improvement of the boron carbide based composite material in the above patent is limited.

Disclosure of Invention

The invention provides a boron carbide-based composite material with high toughness and a preparation method thereof, which are based on low fracture toughness value of boron carbide ceramics and greatly limit the wide application of the boron carbide-based composite material. According to the method, hot-press sintering or spark plasma sintering is adopted, and the purpose of toughening the boron carbide ceramic is achieved through the addition of titanium boride, silicon carbide and metallic molybdenum, so that the requirements of bulletproof armor application are met.

In one aspect, the invention provides a boron carbide-based composite material, which is obtained by taking at least one of molybdenum and tungsten as a toughening phase and boron carbide, titanium boride and silicon carbide as raw materials and performing hot press sintering or spark plasma sintering; the total volume content of the boron carbide, the titanium boride and the silicon carbide is 100vol%, the volume content of the boron carbide is 50-80 vol%, the volume content of the titanium boride is 10-25 vol%, and the volume content of the silicon carbide is 10-25 vol%; the volume content of the toughening phase is 1-20% of the total volume of boron carbide, titanium boride and silicon carbide.

In the invention, the addition of the metal molybdenum or/and tungsten can fully relax the highly concentrated stress at the crack tip region through the plastic deformation of the metal molybdenum or/and tungsten, and absorb energy, thereby improving the crack propagation resistance of the boron carbide-based composite material and further improving the fracture toughness of the boron carbide-based composite material.

Preferably, the volume content of the toughening phase is 2.5-10% of the total volume of the boron carbide, the titanium boride and the silicon carbide. Preferably, the compactness of the boron carbide-based composite material is more than 95%, the Vickers hardness is more than 20GPa, and the fracture toughness is more than or equal to 4.43MPa m ^1/2 。

In another aspect, the present invention also provides a method for preparing a boron carbide-based composite material, comprising:

(1) At least one of tungsten powder and molybdenum powder is taken as raw materials, boron carbide powder, titanium boride powder and silicon carbide powder are mixed, and mixed powder is obtained;

(3) And carrying out hot press sintering or spark plasma sintering on the obtained mixed powder to obtain the boron carbide-based composite material.

In the present disclosure, since molybdenum and tungsten are rare metals, the melting point is high, the strength is high, and the corrosion resistance is good. Mixing boron carbide powder, titanium boride powder, silicon carbide powder and molybdenum powder or tungsten powder to obtain mixed powder, and further hot-pressing sintering or spark plasma sintering to obtain the final composite material. The mechanism of action is mainly crack deflection caused by mismatch of thermal expansion coefficients between titanium boride and boron carbide, and the introduction of silicon carbide, molybdenum or/and tungsten forms a core-shell structure in the material, and the unique structure is beneficial to crack deflection, so that the performance of the material is optimized. Specifically, a part of Mo or/and W enters a solid solution formed by the titanium boride crystal lattice, and further forms a core-shell structure (the core is titanium boride). And the other part of Mo or/and W reacts with boron carbide to generate molybdenum boride or/and tungsten boride, so that the hardness change of the boron carbide-based composite material is kept insignificant. Wherein, the composite material obtained by doping Mo is called molybdenum-containing toughened boron carbide-based composite material. The composite material obtained by doping W can be called as a tungsten-containing toughened boron carbide-based composite material.

Preferably, the particle size of the raw material is 0.1 to 100. Mu.m.

Preferably, the purity of the raw material is 95-99.9%.

Preferably, the parameters of the hot press sintering include: vacuum atmosphere or inert atmosphere, sintering pressure of 30-70 MPa, sintering temperature of 1500-2400 ℃ and heat preservation time of 5-60 minutes.

Preferably, the heating rate of the hot-pressed sintering is 5-20 ℃/min; and after the hot pressed sintering is finished, cooling to room temperature at a cooling rate of 5-100 ℃/min.

Preferably, the parameters of the spark plasma sintering include: vacuum atmosphere or inert atmosphere, sintering pressure of 30-70 MPa, sintering temperature of 1300-2000 ℃ and heat preservation time of 1-20 minutes.

Preferably, the heating rate of the spark plasma sintering is 25-250 ℃/min; after sintering, cooling to 1500-1000 ℃ at a cooling rate of 50-150 ℃/min, and cooling to room temperature along with a furnace.

The beneficial effects are that:

the invention is characterized in that: and adding molybdenum into the boron carbide-based mixed powder to obtain the molybdenum-containing toughened boron carbide-based composite material. The preparation process is simple, and the obtained composite material has excellent performance, wherein the density is more than 98%, the Vickers hardness is more than 20GPa, and the fracture toughness can reach 5.7 MPa.m ^1/2 . Tungsten is added into the boron carbide-based mixed powder to obtain the tungsten-containing toughened boron carbide-based composite material. The obtained composite material has excellent performance, wherein the density is more than 98 percent, the Vickers hardness is more than 25GPa, and the fracture toughness can reach 5.2 MPa.m ^1/2 。

Drawings

FIG. 1 is an SEM image of the polished surface of a molybdenum-containing toughened boron carbide-based composite prepared in example 1, from which it can be seen that the black continuous phase is B ₄ C matrix, bright gray area TiB ₂ Phases, each phase being uniformly dispersed in B ₄ In matrix C and part of TiB ₂ A core-shell structure appears around;

FIG. 2 is a graph of hardness indentation for the molybdenum-containing toughened boron carbide-based composite material prepared in example 1, from which hardness indentation and crack propagation can be seen;

FIG. 3 is an SEM image of the polished surface of a molybdenum-containing toughened boron carbide-based composite prepared in example 2, from which it can be seen that the black continuous phase is B ₄ C matrix, bright gray area TiB ₂ The phases are distributed uniformly, and most of TiB ₂ A core-shell structure appears around;

FIG. 4 is a graph of hardness indentation for the molybdenum-containing toughened boron carbide-based composite material prepared in example 2, from which hardness indentation and crack propagation can be seen;

FIG. 5 is an SEM image of the polished surface of a molybdenum-containing toughened boron carbide-based composite prepared in example 3, from which it can be seen that the black continuous phase is B ₄ C matrix, bright gray area TiB ₂ The phases are distributed uniformly, and most of TiB ₂ A core-shell structure appears around;

FIG. 6 is a graph of hardness indentation for the molybdenum-containing toughened boron carbide-based composite material prepared in example 3, from which hardness indentation and crack growth can be seen;

FIG. 7 is an SEM image of the polished surface of a molybdenum-containing toughened boron carbide-based composite prepared in example 4, from which it can be seen that the black continuous phase is B ₄ C matrix, bright gray area TiB ₂ Phases, each phase is distributed uniformly, and almost all TiB ₂ Core-shell structures appear around the core-shell structures;

FIG. 8 is a graph of hardness indentation for the molybdenum-containing toughened boron carbide-based composite material prepared in example 4, from which hardness indentation and crack growth can be seen;

FIG. 9 is an SEM image of the polished surface of a tungsten-containing toughened boron carbide-based composite prepared according to example 5, from which it can be seen that the black continuous phase is B ₄ C matrix, bright gray area TiB ₂ Phases, each phase being uniformly dispersed in B ₄ In matrix C and part of TiB ₂ Core-shell structures appear around the core-shell structures;

FIG. 10 is a graph of hardness indentation for the tungsten-containing toughened boron carbide-based composite material prepared in example 5, from which hardness indentation and crack growth can be seen;

FIG. 11 is an SEM image of the polished surface of a tungsten-containing toughened boron carbide-based composite prepared according to example 6, from which it can be seen that the black continuous phase is B ₄ C matrix, bright gray area TiB ₂ Phases, each phase being uniformly dispersed in B ₄ C matrix, and most of TiB ₂ A core-shell structure appears around;

FIG. 12 is a graph of hardness indentation for the tungsten-containing toughened boron carbide-based composite material prepared in example 6, from which hardness indentation and crack growth can be seen;

FIG. 13 is an SEM image of the polished surface of a tungsten-containing toughened boron carbide-based composite prepared according to example 7, from which it can be seen that the black continuous phase is B ₄ C matrix, bright gray area TiB ₂ Phases, each phase being uniformly dispersed in B ₄ C matrix, and most of TiB ₂ A core-shell structure appears around;

FIG. 14 is a graph of hardness indentation for the tungsten-containing toughened boron carbide-based composite material prepared in example 7, from which hardness indentation and crack growth can be seen;

FIG. 15 is a tungsten-containing toughened boron carbide prepared in example 8SEM images of the polished surface of the base composite, from which it can be seen that the black continuous phase is B ₄ C matrix, bright gray area TiB ₂ Phases, each phase being uniformly dispersed in B ₄ In matrix C, and almost all TiB ₂ Core-shell structures appear around the core-shell structures;

FIG. 16 is a graph of hardness indentation for the tungsten-containing toughened boron carbide-based composite material prepared in example 8, from which hardness indentation and crack growth can be seen;

FIG. 17 is an SEM image of the polished surface of a boron carbide-based composite prepared according to comparative example 1, from which it can be seen that the black continuous phase is B ₄ C matrix, gray area is SiC phase, white area is TiB ₂ Phases, each of which is uniformly dispersed in B ₄ C, in the matrix;

FIG. 18 is a graph of hardness indentation for the toughened boron carbide based composite material prepared in comparative example 1, from which hardness indentation and crack growth are visible;

FIG. 19 is an SEM image of the core-shell structure of a molybdenum-containing toughened boron carbide-based composite prepared in example 4, as seen in TiB ₂ Forming a core-shell structure near the particles;

FIG. 20 is an SEM image of the core-shell structure of a tungsten-containing toughened boron carbide-based composite prepared in example 5, as seen in TiB ₂ Forming a core-shell structure near the particles;

FIG. 21 is an SEM image of crack propagation of the tungsten-containing toughened boron carbide-based composite prepared in example 5, from which it can be seen that deflection of the core-shell structure occurs during crack propagation.

Detailed Description

The invention is further illustrated by the following embodiments, which are to be understood as merely illustrative of the invention and not limiting thereof.

In the present disclosure, boron carbide powder, titanium boride powder, silicon carbide powder and molybdenum powder (or/and tungsten powder) are used as matrix materials, and mixed to obtain mixed powder. And then carrying out hot pressing or spark plasma sintering treatment at 1200-2400 ℃ in vacuum or inert atmosphere to obtain the boron carbide-based composite material. Wherein the addition of the metallic molybdenum can refine grains and crackThe expansion deflects to play a role in toughening, and specific mechanisms include: the introduction of Mo and/or W can be wrapped in TiB ₂ The surface of the particles forms a core-shell structure (wherein the shell is a solid solution formed by molybdenum or/and tungsten entering titanium boride crystal lattice), grains are refined, cracks are deflected to grow, and the toughening effect is further achieved; the introduction of Mo and W facilitates the transition of the composite from the through-grain fracture to the deflection along the grain fracture and crack propagation path.

In an alternative embodiment, the raw materials (matrix raw material+toughening phase raw material) are ball-milled in an ethanol solvent to obtain mixed slurry, and then dried and sieved to obtain mixed powder. In the ball milling process, the ball milling media (milling balls) are silicon carbide balls. Raw material powder in the ball milling process: grinding ball: the ethanol solvent may be 1:2:1. the rotating speed of the ball milling process is not more than 300r/min. The ball milling process is not more than 24 hours. Wherein the drying temperature can be 40-70 ℃ and the drying time can be 6-24 hours. The sieving can be through a 80-200 mesh sieve. Although titanium boride and silicon carbide also play a role in toughening during sintering of titanium boride, the titanium boride and silicon carbide are classified into matrix materials in the invention, and the toughening phase only refers to at least one of molybdenum and tungsten unless otherwise specified.

In an alternative embodiment, the mixed powder may comprise the following components in volume ratio: the volume content of the boron carbide may be 50 to 80vol%, the volume content of the titanium boride may be 10 to 25vol%, and the volume content of the silicon carbide may be 10 to 25vol%, based on 100vol% of the total volume content of the boron carbide, the titanium boride and the silicon carbide. Wherein the volume content of the toughening phase can be 1-20% of the total volume of boron carbide, titanium boride and silicon carbide, and is preferably 2.5-10%. Preferably, the volume content of the boron carbide may be 60 to 80vol%, the volume content of the titanium boride may be 10 to 20vol%, and the volume content of the silicon carbide may be 10 to 20vol%, based on 100vol% of the total volume content of the boron carbide, the titanium boride, and the silicon carbide. More preferably, the volume content of the boron carbide may be 70 to 80vol%, the volume content of the titanium boride may be 10 to 15vol%, and the volume content of the silicon carbide may be 10 to 15vol%, based on 100vol% of the total volume content of the boron carbide, the titanium boride, and the silicon carbide.

In alternative embodiments, the particle size of the boron carbide, titanium boride, silicon carbide and molybdenum powder (or/and tungsten powder) may be in the range of 0.1 to 100 μm; the purity of boron carbide, titanium boride, silicon carbide and molybdenum powder (or/and tungsten powder) can be 95-99.9%.

Wherein, hot press sintering includes: under the protection of vacuum or inert atmosphere, the temperature rising rate is 5-20 ℃/min, the sintering pressure is 30-70 MPa, the sintering temperature is 1500-2400 ℃, the heat preservation time is 5-60 minutes, the temperature is reduced to room temperature at the rate of 5-100 ℃/min, and the furnace is opened and the mold is released.

Wherein the spark plasma sintering comprises: in vacuum or inert atmosphere, the temperature rising rate is 25-250 ℃/min, the sintering pressure is 30-70 MPa, the sintering temperature is 1300-2000 ℃, and the heat preservation time is 1-20 minutes. After the heat preservation is finished, cooling to 1500-1000 ℃ at a speed of 50-150 ℃/min, cooling to room temperature along with a furnace, and demoulding to obtain a sintered sample.

The resulting boron carbide-based composite is simply roughed, for example, by grinding with a surface grinder. And then polishing to obtain the smooth and compact boron carbide-based composite material. The polishing solution used was a diamond suspension. Polishing with the polishing liquid may be performed in order of 20 μm, 10 μm, 9 μm, 5 μm, 3 μm, 1 μm, 0.5 μm. After polishing, the polishing surface roughness of the boron carbide-based composite material is 0.5 mu m.

The density of the molybdenum-containing toughened boron carbide-based composite material obtained by adopting an Archimedes principle test in the invention is more than 98%. The Vickers hardness of the molybdenum-containing toughened boron carbide-based composite material is more than 20GPa. The fracture toughness of the molybdenum-containing toughened boron carbide-based composite material calculated by adopting a hardness indentation method is 4.33-5.73 MPa m ^1/2 . The density of the molybdenum-containing toughened boron carbide-based composite material obtained by adopting the Archimedes principle test is 2.9753-3.5206 g/cm ³ The method comprises the steps of carrying out a first treatment on the surface of the The apparent porosity of the molybdenum-containing toughened boron carbide-based composite material obtained by adopting Archimedes principle calculation is 1.88-0.43%;

in the present invention, archimedes' original is adoptedThe compactness of the tungsten-containing toughened boron carbide-based composite material obtained by the physical test is more than 98%. The Vickers hardness of the tungsten-containing toughened boron carbide-based composite material is more than 20GPa. The fracture toughness of the tungsten-containing toughened boron carbide-based composite material calculated by adopting a hardness indentation method is 4.8-5.2 MPa.m ^1/2 . The density of the tungsten-containing toughened boron carbide-based composite material obtained by adopting the Archimedes principle test is 3.1979-4.3063 g/cm ³ The method comprises the steps of carrying out a first treatment on the surface of the The apparent porosity of the tungsten-containing toughened boron carbide-based composite material obtained by adopting Archimedes principle calculation is 1.46-0.68%.

The present invention will be further illustrated by the following examples. It is also to be understood that the following examples are given solely for the purpose of illustration and are not to be construed as limitations upon the scope of the invention, since numerous insubstantial modifications and variations will now occur to those skilled in the art in light of the foregoing disclosure. The specific process parameters and the like described below are also merely examples of suitable ranges, i.e., one skilled in the art can make a suitable selection from the description herein and are not intended to be limited to the specific values described below.

Example 1

(1) Preparation of the slurry

18.90g of boron carbide, 5.88g of titanium boride, 3.85g of silicon carbide, 2.55g of metallic molybdenum powder, 31.18g of absolute ethyl alcohol and 62.36g of silicon carbide balls are weighed into a ball milling tank. And placing the ball milling tank in a planetary ball mill for ball milling. In an alternative embodiment, the average particle size of the boron carbide is 0.5 μm, the purity is 99%, the average particle size of the titanium boride is 1.5 μm, the purity is 98%, the average particle size of the silicon carbide is 0.6 μm, the purity is 98%, the diameter of the silicon carbide balls is 5mm, the rotational speed of the ball mill is 300r/min, and the ball milling time is 24 hours.

(2) Preparation of raw powder

And (3) placing the mixed slurry obtained after ball milling in a blast drying oven for drying, and grinding and sieving to obtain mixed raw material powder. In an alternative embodiment, the oven temperature is 60 ℃ and the drying time is 12 hours, and the screen used for the screening is a 100 mesh screen.

(3) Preparation of composite materials

And 5g of the mixed raw material powder is taken to be filled in a graphite mould and then is placed in a discharge plasma sintering furnace for sintering, so that the compact boron carbide-based composite material is obtained. In an alternative embodiment, the graphite mold has an inner diameter of 20mm, a sintering temperature of 1850 ℃, a soak time of 10 minutes, and the sintering atmosphere is vacuum.

(4) Sample processing

And (3) performing preliminary rough machining on the boron carbide-based composite material obtained by sintering on a plane grinding machine, polishing the diamond polishing solution, performing ultrasonic cleaning on the polished diamond polishing solution for 1 hour by using alcohol, and finally performing characterization test on the sample.

The boron carbide-based composite material prepared in this example 1 had a density of 97.81%, a Vickers hardness of 23.8GPa and a fracture toughness of 4.43 MPa.m ^1/2 . Fig. 1 is an SEM image of the boron carbide-based composite of example 1, showing that the pores in the sample are less, the density of the sample is higher, and the additive phase is uniformly dispersed in the matrix phase. FIG. 2 is a graph of mechanical test indentations of the boron carbide-based composite material prepared in example 1, the average value of six large indentations being calculated to give a Vickers hardness of 23.8GPa and a fracture toughness of 4.43MPa m ^1/2 。

Example 2

(1) Preparation of the slurry

18.90g of boron carbide, 5.88g of titanium boride, 3.85g of silicon carbide, 5.10g of metallic molybdenum powder, 33.73g of absolute ethyl alcohol and 67.46g of silicon carbide balls are weighed into a ball milling tank. The ball milling pot is placed in a planetary ball mill for ball milling. In an alternative embodiment, the average particle size of the boron carbide is 0.5 μm, the purity is 99%, the average particle size of the titanium boride is 1.5 μm, the purity is 98%, the average particle size of the silicon carbide is 0.6 μm, the purity is 98%, the diameter of the silicon carbide balls is 5mm, the rotational speed of the ball mill is 300r/min, and the ball milling time is 24 hours.

(2) Preparation of raw powder

(3) Preparation of composite materials

And 5g of the mixed raw material powder is taken and filled in a graphite mold and then sintered in a discharge plasma sintering furnace, so as to obtain the compact boron carbide-based composite material. In a further alternative embodiment, the graphite mold has an inner diameter of 20mm, a sintering temperature of 1850 ℃, a holding time of 10 minutes, and a sintering atmosphere of vacuum.

(4) Sample processing

The boron carbide-based composite material prepared in this example 2 had a density of 97.75%, a Vickers hardness of 22.8GPa and a fracture toughness of 5.28 MPa.m ^1/2 . Fig. 3 is an SEM image of the boron carbide based composite of example 2, showing that the pores in the sample are less, the density of the sample is higher, and the additive phase is uniformly dispersed in the matrix phase. FIG. 4 is a graph of mechanical test indentations of the boron carbide-based composite of example 2, calculated from the average of six large indentations, to give a Vickers hardness of 22.8GPa and a fracture toughness of 5.28MPa m ^1/2 。

Example 3

(1) Preparation of the slurry

18.90g of boron carbide, 5.88g of titanium boride, 3.85g of silicon carbide, 7.65g of metallic molybdenum powder, 36.28g of absolute ethyl alcohol and 72.56g of silicon carbide balls are weighed and placed in a ball milling tank. The ball milling pot is placed in a planetary ball mill for ball milling. In an alternative embodiment, the average particle size of the boron carbide is 0.5 μm, the purity is 99%, the average particle size of the titanium boride is 1.5 μm, the purity is 98%, the average particle size of the silicon carbide is 0.6 μm, the purity is 98%, the diameter of the silicon carbide balls is 5mm, the rotational speed of the ball mill is 300r/min, and the ball milling time is 24 hours.

(2) Preparation of raw powder

(3) Preparation of composite materials

(4) Sample processing

The boron carbide-based composite material prepared in this example 3 had a density of 98.58%, a Vickers hardness of 20.8GPa and a fracture toughness of 5.32MPa m ^1/2 . Fig. 5 is an SEM image of the boron carbide-based composite of example 3, showing that there are few macroscopic pores in the sample, the density of the sample is higher, and the additive phase is uniformly dispersed in the matrix phase. FIG. 6 is a graph of mechanical test indentations of the boron carbide-based composite of example 3, showing that the Vickers hardness is 20.8GPa and the fracture toughness is 5.32MPa m calculated from the average of six large indentations ^1/2 。

Example 4

(1) Preparation of the slurry

18.90g of boron carbide, 5.88g of titanium boride, 3.85g of silicon carbide, 10.2g of metallic molybdenum powder, 38.83g of absolute ethyl alcohol and 77.66g of silicon carbide balls are weighed and placed in a ball milling tank. The ball milling pot is placed in a planetary ball mill for ball milling. In an alternative embodiment, the average particle size of the boron carbide is 0.5 μm, the purity is 99%, the average particle size of the titanium boride is 1.5 μm, the purity is 98%, the average particle size of the silicon carbide is 0.6 μm, the purity is 98%, the diameter of the silicon carbide balls is 5mm, the rotational speed of the ball mill is 300r/min, and the ball milling time is 24 hours.

(2) Preparation of raw powder

(3) Preparation of composite materials

(4) Sample processing

The boron carbide-based composite material prepared in example 4 had a density of 99.7%, a Vickers hardness of 19.9GPa and a fracture toughness of 5.73MPa m ^1/2 . Fig. 7 is an SEM image of the boron carbide based composite of example 4, showing that there are few macroscopic pores in the sample, the sample is fully dense, and the additive phase is uniformly dispersed in the matrix phase. FIG. 8 is a graph of mechanical test indentations of the boron carbide-based composite of example 4, calculated from the average of six large indentations, to give a Vickers hardness of 19.9GPa and a fracture toughness of 5.73MPa m ^1/2 。

Example 5

The preparation process of the boron carbide-based composite material in this example 5 is described with reference to example 1, except that: 18.90g of boron carbide, 5.88g of titanium boride, 3.85g of silicon carbide and 4.84g of tungsten metal powder are weighed.

Example 6

The preparation process of the boron carbide-based composite material in this example 5 is described with reference to example 5, except that: the other components in the raw material composition are unchanged, and the metal tungsten powder is 9.68g.

Example 7

The preparation process of the boron carbide-based composite material in this example 5 is described with reference to example 5, except that: the other components in the raw material composition are unchanged, and the metal tungsten powder is 14.51g.

Example 8

The preparation process of the boron carbide-based composite material in this example 5 is described with reference to example 5, except that: the other components in the raw material composition are unchanged, and the metal tungsten powder is 19.35g.

Comparative example 1

The preparation process of the boron carbide-based composite material in this comparative example 1 is described with reference to example 1, except that: no toughening phase is added.

Table 1 shows the compositions of the boron carbide-based composite materials prepared by the invention and the performance parameters thereof:

the foregoing description of the preferred embodiments of the invention is not intended to limit the invention to the precise form disclosed, and any such modifications, equivalents, and alternatives falling within the spirit and scope of the invention are intended to be included within the scope of the invention.

Claims

1. The boron carbide-based composite material is characterized in that at least one of molybdenum and tungsten is used as a toughening phase, boron carbide, titanium boride and silicon carbide are used as raw materials, the toughening phase and the raw materials are put into an ethanol solvent, siC is ball-milled to obtain mixed slurry, and then the mixed slurry is dried and sieved to obtain mixed powder; finally, carrying out hot press sintering or spark plasma sintering on the mixed powder to obtain the powder; the grain diameter of the raw materials is 0.1-100 mu m;

the total volume content of the boron carbide, the titanium boride and the silicon carbide is calculated as 100%, the volume content of the boron carbide is 50-80%, the volume content of the titanium boride is 10-25%, and the volume content of the silicon carbide is 10-25%;

the volume content of the toughening phase is 2.5-10% of the total volume of boron carbide, titanium boride and silicon carbide;

the parameters of the hot press sintering include: vacuum atmosphere or inert atmosphere, sintering pressure of 30-70 MPa, sintering temperature of 1500-2400 ℃ and heat preservation time of 5-60 minutes; the heating rate of the hot-pressed sintering is 5-20 ℃/min; after the hot pressed sintering is completed, cooling to room temperature at a cooling rate of 5-100 ℃/min;

the parameters of the spark plasma sintering include: vacuum atmosphere or inert atmosphere, sintering pressure of 30-70 MPa, sintering temperature of 1300-2000 ℃ and heat preservation time of 1-20 minutes; the heating rate of the spark plasma sintering is 25-250 ℃/min; after sintering, cooling to 1500-1000 ℃ at a cooling rate of 50-150 ℃/min, and cooling to room temperature along with a furnace.

2. The boron carbide-based composite material of claim 1, wherein the boron carbide-based composite material has a density of > 95%, a vickers hardness of > 20GPa, and a fracture toughness of > 4.43mpa m ^1/2 。

3. The boron carbide based composite material of claim 1, wherein the feedstock has a purity of 95 to 99.9%.