阅读说明：本技术 一种高熵硼化物基陶瓷及其制备方法和应用 (High-entropy boride-based ceramic and preparation method and application thereof ) 是由 郭伟明 许亮 谭大旺 林华泰 于 2019-08-28 设计创作，主要内容包括：本发明属于陶瓷切削刀具领域,公开了一种高熵硼化物基陶瓷及其制备方法和应用。所述高熵硼化物基陶瓷是将高熵硼化物陶瓷粉(A<Sub>0.2</Sub>B<Sub>0.2</Sub>C<Sub>0.2</Sub>D<Sub>0.2</Sub>E<Sub>0.2</Sub>)B<Sub>2</Sub>、添加剂B<Sub>4</Sub>C和SiC进行球磨混合,干燥后得到混合粉体,所述A、B、C、D和E分别为Ti、Zr、Hf、V、Nb、Ta、C、Mo或W中互异的元素,再将混合粉体经放电等离子法在真空中升温至1000～1500℃,再在氩气气氛下,轴向加压为25～50MPa,升温至1800～2000℃烧结制得。本发明的高熵硼化物基陶瓷的硬度高,化学稳定性好,具有较好的耐磨性和切削性能,可应用于难加工材料的切削刀具领域中。(The invention belongs to the field of ceramic cutting tools, and discloses high-entropy boride-based ceramic and a preparation method and application thereof. The high-entropy boride-based ceramic is prepared by mixing high-entropy boride ceramic powder (A) 0.2 B 0.2 C 0.2 D 0.2 E 0.2 )B 2 Additive B 4 And C and SiC are subjected to ball milling and mixing, drying is carried out, mixed powder is obtained, wherein A, B, C, D and E are respectively elements different from each other in Ti, Zr, Hf, V, Nb, Ta, C, Mo or W, the mixed powder is heated to 1000-1500 ℃ in vacuum through a discharge plasma method, axial pressurization is carried out to 25-50 MPa in argon atmosphere, and the temperature is raised to 1800-2000 ℃ for sintering, so that the high-performance silicon carbide ceramic is obtained. The high-entropy boride-based ceramic disclosed by the invention is high in hardness, good in chemical stability, better in wear resistance and cutting performance, and capable of being applied to cutting of difficult-to-process materialsThe field of cutting tools.)

1. A high-entropy boride-based ceramic characterized in that the high-entropy boride-based ceramic is prepared by mixing (A) a high-entropy boride ceramic powder_0.2B_0.2C_0.2D_0.2E_0.2)B₂Additive B₄And C and SiC are subjected to ball milling and mixing, drying is carried out, mixed powder is obtained, wherein A, B, C, D and E are respectively elements different from each other in Ti, Zr, Hf, V, Nb, Ta, C, Mo or W, the mixed powder is heated to 1000-1500 ℃ in vacuum through a discharge plasma method, axial pressurization is carried out to 25-50 MPa in argon atmosphere, and the temperature is raised to 1800-2000 ℃ for sintering, so that the high-performance silicon carbide ceramic is obtained.

2. The high-entropy boride-based ceramic according to claim 1, wherein the high-entropy boride-based ceramic has a relative density of 98 to 100%, the high-entropy boride-based ceramic has a hardness of 22 to 28GPa, and the high-entropy boride-based ceramic has a fracture toughness of 4 to 7 MPa-m^1/2(ii) a The bending strength of the high-entropy boride-based ceramic is 600-900 MPa.

3. A high entropy boride-based ceramic according to claim 1, wherein (A) is_0.2B_0.2C_0.2D_0.2E_0.2)B₂：B₄C: the volume ratio of SiC is (10-18): (1-5): (1-5).

4. The high-entropy boride-based ceramic of claim 1, wherein the cemented carbide balls used in the ball milling mixing are YG6 balls, the rotation speed of the ball milling is 150-300 r/min, and the time of the ball milling mixing is 6-24 h.

5. A high entropy boride-based ceramic according to claim 1, wherein (A) is_0.2B_0.2C_0.2D_0.2E_0.2)B₂The purity of the powder is 98-99.99 wt.%, and the particle size is 0.5-3 μm; b is₄The purity of the C powder is 97-99.99 wt.%, the particle size is 0.5-1.5 μm, the purity of the SiC powder is 98-99.99 wt.%, and the particle size is 200-500 nm.

6. The high-entropy boride-based ceramic according to claim 1, wherein the temperature increase rate of the temperature increase to 1000 to 1500 ℃ is 150 to 300 ℃/min, and the temperature increase rate of the temperature increase to 1800 to 2000 ℃ is 50 to 100 ℃/min.

7. The high-entropy boride-based ceramic of claim 1, wherein the sintering time at a temperature of 1800 to 2000 ℃ is 5 to 20 min.

8. A preparation method of a high-entropy boride-based ceramic according to any one of claims 1 to 7, characterized by comprising the following specific steps:

s1, mixing (A)_0.2B_0.2C_0.2D_0.2E_0.2)B₂Powder and additive B₄Mixing C-SiC, drying to obtain (A)_0.2B_0.2C_0.2D_0.2E_0.2)B₂-B₄C-SiC mixed powder;

s2, mixing (A)_0.2B_0.2C_0.2D_0.2E_0.2)B₂-B₄Placing the C-SiC mixed powder into a graphite die of a discharge plasma sintering furnace, heating to 1000-1500 ℃ at 150-300 ℃/min under the condition of a vacuum degree of less than 1mbar, then filling 1atm of argon, axially pressurizing to 30-50 MPa after filling, heating to 1800-2000 ℃ at 50-100 ℃/min at the same time of beginning filling, calcining for 5-20 min, cooling to 700-900 ℃ at 50-150 ℃/min, axially releasing pressure, and cooling along with the furnace to obtain the high-entropy boride-based ceramic.

9. Use of the high entropy boride-based ceramic according to any one of claims 1 to 7 in the field of cutting tools.

10. The application of the high-entropy boride-based ceramic in the field of cutting tools as claimed in claim 9, wherein the relative density of the high-entropy boride-based ceramic cutting tool is 98-100%, the hardness of the boride-based ceramic cutting tool is 22-28 GPa, and the fracture toughness of the boride-based ceramic cutting tool is 4-7 MPa-m^1/2(ii) a The bending strength of the boride-based ceramic cutter is 600-900 MPa.

Technical Field

The invention belongs to the technical field of ceramic cutting tools, and particularly relates to high-entropy boride-based ceramic and a preparation method and application thereof.

Background

The high-entropy ceramic is a high-entropy solid solution of an inorganic non-metallic material, and is a single-phase ceramic material formed by combining more than 4 equal-proportion metal elements and a plurality of non-metallic elements. The boride ceramic is a ceramic material with high melting point and high hardness, and has excellent high-temperature resistance and wear resistance. The high-entropy boride is a high-entropy solid solution formed by combining multiple transition group metal elements with equal atomic ratio and B atoms, and is a single-phase multi-boride crystal. Wherein the chemical formula of the 5-element high-entropy boride is (A)_0.2B_0.2C_0.2D_0.2E_0.2)B₂ABCDE is metal elements of IVB, VB and VIB groups, the content of various metal elements in the crystal is equal, and the crystal structure is a close-packed hexagonal structure. The high-entropy boride has high melting point (more than 3000 ℃), excellent high-temperature strength and good high-temperature creep resistance, and can be used in the field of high-temperature structural materials. Meanwhile, compared with the monobasic boride, the high-entropy boride has higher hardness and better stability, but has poorer toughness, so the application of the pure high-entropy boride ceramic is limited.

At present, boride-based ceramic cutting tools are mainly made of TiB₂Mainly, is suitable for high-speed cutting hardening stainless steel, hardening titanium alloy and other difficult-to-process materials. The research of the high-entropy boride ceramic mainly focuses on the synthesis of ceramic powder and the sintering preparation of the pure high-entropy boride ceramic. At present, the hardness of the pure high-entropy boride ceramic is about 20 percent higher than that of a monobasic boride, the toughness of the pure high-entropy boride ceramic is lower than that of the monobasic boride ceramic, the high hardness of the high-entropy boride ceramic can be reserved by adding an additive and a second phase and controlling a sintering process, and meanwhile, the toughness is greatly improved, so that the high-entropy boride-based ceramic cutter material with high hardness, high toughness and high temperature resistance is obtained. Due to the excellent mechanical property, the cutting tool used for high-speed machining can obtain better machining performance than a monobasic boride tool. At present, the boride-based ceramic material prepared by the technology and the application thereof in the field of cutters are not reported.

Disclosure of Invention

In order to solve the above-mentioned drawbacks and disadvantages of the prior art, the present invention aims to provide a high entropy boride-based ceramic.

The invention also aims to provide a preparation method of the high-entropy boride-based ceramic. The method comprises the steps of preparing high-entropy boride ceramic powder and an additive B₄C and SiC are used as raw materials, and the preparation of the high-entropy boride-based ceramic is realized through Spark Plasma Sintering (SPS).

The invention also aims to provide application of the high-entropy boride-based ceramic.

The purpose of the invention is realized by the following technical scheme:

a high-entropy boride-based ceramic which is prepared by mixing high-entropy boride ceramic powder (A)_0.2B_0.2C_0.2D_0.2E_0.2)B₂Additive B₄And C and SiC are subjected to ball milling and mixing, drying is carried out, mixed powder is obtained, wherein A, B, C, D and E are respectively elements different from each other in Ti, Zr, Hf, V, Nb, Ta, C, Mo or W, the mixed powder is heated to 1000-1500 ℃ in vacuum through a discharge plasma method, axial pressurization is carried out to 25-50 MPa in argon atmosphere, and the temperature is raised to 1800-2000 ℃ for sintering, so that the high-performance silicon carbide ceramic is obtained.

Preferably, the relative density of the high-entropy boride-based ceramic is 98-100%, the hardness of the high-entropy boride-based ceramic is 22-28 GPa, and the fracture toughness of the high-entropy boride-based ceramic is 4-7 MPa-m^1/2(ii) a The bending strength of the high-entropy boride-based ceramic is 600-900 MPa.

Preferably, the (A) is_0.2B_0.2C_0.2D_0.2E_0.2)B₂：B₄C: the volume ratio of SiC is (10-18): (1-5): (1-5).

Preferably, the hard alloy balls used in the ball milling mixing are YG6 balls, the rotation speed of the ball milling is 150-300 r/min, and the time of the ball milling mixing is 6-24 h.

Preferably, the (A) is_0.2B_0.2C_0.2D_0.2E_0.2)B₂The purity of the powder is 98-99.99 wt.%, and the particle size is 0.5-3 μm; b is₄The purity of the C powder is 97-99.99 wt.%, the particle size is 0.5-1.5 mu m, and the purity of the SiC powder is 98-9999 wt.% and a particle size of 200-500 nm.

Preferably, the heating rate of heating to 1000-1500 ℃ is 150-300 ℃/min, and the heating rate of heating to 1800-2000 ℃ is 50-100 ℃/min.

Preferably, the sintering time for raising the temperature to 1800-2000 ℃ is 5-20 min.

The preparation method of the high-entropy boride-based ceramic comprises the following specific steps:

s1, mixing (A)_0.2B_0.2C_0.2D_0.2E_0.2)B₂Powder and additive B₄Mixing C-SiC, drying to obtain (A)_0.2B_0.2C_0.2D_0.2E_0.2)B₂-B₄C-SiC mixed powder;

s2, mixing (A)_0.2B_0.2C_0.2D_0.2E_0.2)B₂-B₄Placing the C-SiC mixed powder into a graphite die of a discharge plasma sintering furnace, heating to 1000-1500 ℃ at 150-300 ℃/min under the condition of a vacuum degree of less than 1mbar, then filling 1atm of argon, axially pressurizing to 30-50 MPa after filling, heating to 1800-2000 ℃ at 50-100 ℃/min at the same time of beginning filling, calcining for 5-20 min, cooling to 700-900 ℃ at 50-150 ℃/min, axially releasing pressure, and cooling along with the furnace to obtain the high-entropy boride-based ceramic.

The high-entropy boride-based ceramic is applied to the field of cutting tools.

Preferably, the relative density of the high-entropy boride-based ceramic cutter is 98-100%, the hardness of the boride-based ceramic cutter is 22-28 GPa, and the fracture toughness of the boride-based ceramic cutter is 4-7 MPa-m^1/2(ii) a The bending strength of the boride-based ceramic cutter is 600-900 MPa

Compared with the prior art, the invention has the following beneficial effects:

1. the high-entropy boride-based ceramic has high hardness and high wear resistance, and the high-entropy boride has excellent hardness, inhibits the growth of crystal grains in a sintering process through a reinforcing phase, shortens the time of crystal grain growth through a rapid discharge plasma sintering mode on the premise of ensuring the compactness, and realizes the preparation of the high-entropy boride-based ceramic with fine grains, high hardness, high strength and high toughness.

2. The high-entropy boride-based ceramic has higher hardness than that of a monobasic boride, and the boride has better high-temperature strength and hardness than that of traditional ceramics such as alumina and silicon nitride, so that the hardness can be further improved by inhibiting the growth of crystal grains, and the strength can be further improved by a reinforcing phase, therefore, the high-entropy boride-based ceramic has good wear resistance and cutting performance, can be applied to high-speed processing of materials difficult to process, and has processing performance obviously superior to that of the monobasic boride ceramic and the traditional ceramics such as alumina and silicon nitride.

Drawings

FIG. 1 is a micrograph of a high entropy boride based ceramic body prepared in example 1.

FIG. 2 is a micrograph of a titanium boride-based ceramic body prepared in comparative example 1.

Detailed Description

The following examples are presented to further illustrate the present invention and should not be construed as limiting the invention.

(A) used in the practice of the invention_0.2B_0.2C_0.2D_0.2E_0.2)B₂The purity of the powder is 98-99.99 wt.%, and the particle size is 0.5-3 μm; b is₄The purity of the C powder is 97-99.99 wt.%, the particle size is 0.5-1.5 μm, the purity of the SiC powder is 98-99.99 wt.%, and the particle size is 200-500 nm.