High-entropy carbide composite ceramic as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of high-entropy ceramics, and discloses a high-entropy carbide composite ceramic as well as a preparation method and application thereof. The molecular formula of the ceramic is (TixHfyVzTamWn) C-Co, x + y + z + m + n is equal to 1, x is equal to 0.175-0.25, y is equal to 0.175-0.25, z is equal to 0.175-0.25, m is equal to 0.175-0.25, and n is equal to 0.1-0.3, and the preparation method comprises the following steps: adding mixed powder of TiO2 powder, HfO2 powder, V2O5 powder, Ta2O5 powder, WO3 powder and graphite powder into absolute ethyl alcohol to prepare slurry, carrying out ball milling, carrying out dry pressing to obtain a biscuit, carrying out pressureless sintering under vacuum, mixing the obtained high-entropy powder with Co powder, carrying out ball milling, carrying out dry pressing to obtain a green body, and carrying out SPS sintering under 25-30 MPa and 1600-1700 DEG C. The method can be applied to the field of cutting tool preparation.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of high-entropy ceramics, and more particularly relates to a high-entropy carbide composite ceramic ( (Ti, Hf, V, Ta, W) C-Co) and a preparation method and application thereof. BACKGROUND

[0002] High-entropy carbide ceramics have advantages of high hardness, high wear resistance, high chemical stability and excellent high-temperature mechanical properties, and are expected to be applied to the field of cutting tools. However, two problems have always plagued the development of high-entropy carbide ceramic tools, that is, a too high sintering temperature and poor fracture toughness.

[0003] Transition metal carbides have been widely used in the field of cutting tools. For example, WC has become one of the most important materials for manufacturing most of the forming and cutting tools due to its excellent mechanical properties, such as high strength, high hardness and high wear resistance. However, due to the low fracture toughness, the service life of the cutting tools is generally low. With the deepening of research, it is found that the cutting performance of a binary transition metal carbide ceramic such as TiC-Cr3C2 ceramic is better than that of a ceramic tool and a Ti (C, N) -based metal ceramic tool in an Al2O3 ceramic steel continuous cutting test enhanced by WC. As a multi-component single carbide material, high-entropy carbide ceramics have high mechanical properties and excellent wear resistance, and are potential cutting tool materials. However, due to the delayed diffusion effect of different transition metal elements during sintering, the solid solution of high-entropy carbide is not complete, thereby affecting the mechanical properties. Therefore, it is urgent to solve the problem of how to maintain the single-phase solid solution while achieving high hardness and high toughness. SUMMARY

[0004] In order to solve the above-mentioned problems existing in the prior art and shortcomings, the primary purpose of the present application is to provide a high-entropy carbide composite ceramic. The high-entropy carbide composite ceramic is (Ti, Hf, V, Ta, W) C-Co, which has high hardness and high toughness, and the cutting performance is obviously improved.

[0005] Another purpose of the present application is to provide a preparation method of the high-entropy carbide composite ceramic. The method significantly improves the solid solution effect of (Ti, Hf, V, Ta, Ta) C high-entropy ceramic by changing the content of W under the premise of realizing ceramic densification and maintaining the mechanical properties of high-entropy carbide ceramic.

[0006] Still another purpose of the present application is to provide the application of the high-entropy carbide composite ceramic.

[0007] The purposes of the present application are achieved by the following technical solutions: A high-entropy carbide composite ceramic has a molecular formula of (Ti xHf y V z Ta m W n C-Co, wherein x+y+z+m+n=1, x=0.175~0.25, y=0.175~0.25, z=0.175~0.25, m=0.175~0.25, n=0.1~0.3, TiO2 powder, HfO2 powder, V2O5 powder, Ta2O5 powder, WO3 powder and graphite powder are mixed to obtain a mixed powder, the mixed powder is added into anhydrous ethanol and stirred to obtain a slurry, the slurry is ball milled, dried, sieved and then dry-pressed into a green body, the green body is sintered at 1500~1600℃ under vacuum without pressure to obtain a high-entropy powder; the high-entropy powder and Co powder are mixed, added into anhydrous ethanol and ultrasonically stirred to obtain a slurry, the slurry is ball milled, dried, sieved and then dry-pressed into a green body; the green body is sintered by SPS at 1600~1700℃ under a uniaxial pressure of 25~30 MPa to obtain the high-entropy carbide composite ceramic.

[0008] Preferably, the high-entropy carbide composite ceramic has a Vickers hardness of 25~26.5 GPa and a fracture toughness of 4~5.7 MPa·m 1 / 2 , and a service life of 1673~16170 m for cutting cast iron.

[0009] Preferably, the TiO2 powder, HfO2 powder, V2O5 powder, Ta2O5 powder and WO3 powder each has a particle size of 1~2 μm; the graphite powder has a particle size of 100 nm~1 μm; and the Co powder has a particle size of 0.4~0.5 μm.

[0010] Preferably, the volume ratio of the high-entropy powder to the Co powder is (47~48):(2~3).

[0011] Preferably, the TiO2 powder, HfO2 powder, V2O5 powder, Ta2O5 powder, WO3 powder and graphite powder have a molar ratio of (0.175~1):(0.175~1):(0.0875~0.5):(0.0875~0.5):(0.1~0.3):(2~4).

[0012] The preparation method of the high-entropy carbide composite ceramic comprises the following steps: S1. mixing TiO2 powder, HfO2 powder, V2O5 powder, Ta2O5 powder, WO3 powder and graphite powder to obtain a mixed powder; S2. adding the mixed powder into anhydrous ethanol and ultrasonically stirring to obtain a slurry, then ball milling, drying, sieving and dry-pressing into a green body, and sintering the green body at 1500~1600℃ under vacuum without pressure to obtain a C high-entropy powder; S3. The high-entropy powder and Co powder are mixed and added into anhydrous ethanol for ultrasonic stirring to obtain a slurry, and then the slurry is ball milled, dried, sieved, and dry-pressed into a green body; S4. The green body is sintered by SPS at a uniaxial pressure of 25-30 MPa and a temperature of 1600-1700 DEG C and is kept for heat preservation to obtain a high-entropy carbide composite ceramic with a molecular formula of (Ti x Hf y V z Ta m W n )C-Co.

[0013] Preferably, the rotating speed of the ball milling in step S2 is 100-300 r / min, the ball milling time is 18-36 h, the drying temperature is 60-80 DEG C, and the drying time is 12-24 h.

[0014] Preferably, the vacuum degree of the vacuum in step S2 is less than or equal to 10 Pa, the temperature rising program is first rising at a rate of 15-20 DEG C / min to 50-1000 DEG C, and then rising at a rate of 8-10 DEG C / min to 1500-1600 DEG C, and the sintering time is 1.5-2.5 h.

[0015] Preferably, the rotating speed of the ball milling in step S3 is 100-200 r / min, the ball milling time is 18-36 h, the drying temperature is 60-80 DEG C, and the drying time is 16-24 h, the temperature rising rate in step S4 is 80-100 DEG C / min, and the heat preservation time is 10-15 min.

[0016] The high-entropy carbide composite ceramic is applied to the preparation of a cutting tool.

[0017] Compared with the prior art, the present application has the following beneficial effects: 1. The high-entropy carbide composite ceramic (Ti, Hf, V, Ta, W)C-Co prepared in the present application has high hardness and high toughness, and the cutting performance is obviously improved by adjusting the content of W during sintering, and W promotes the solid solution process. 1 / 2, and the service life of cutting ductile cast iron is 8163 m. The HEC-W(1-3)-Co high-entropy composite ceramics all show good solid solution effect, in which the solid solution effect and mechanical properties of HEC-W3-Co are the best, the Vickers hardness is 25.7-26.2 GPa, and the fracture toughness is 4-5.7 MPa·m 1 / 2 , and the service life of cutting ductile cast iron is 16170 m.

[0018] 2. The application adopts Co alloy as the adhesive, and forms a low-melting-point liquid phase in the sintering process, which can promote the low-temperature densification process, has fast sintering speed, reduces the sintering temperature, and is energy-saving and environment-friendly. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 XRD patterns of high-entropy carbide powders with different W contents prepared in Examples 1-3 and carbide powders of Comparative Example 1. DETAILED DESCRIPTION

[0020] The application will be further described in combination with specific examples, but should not be understood as a limitation to the application. If not specifically indicated, the technical means used in the examples are conventional means familiar to those skilled in the art. Unless specifically indicated, the reagents, methods and equipment used in the application are conventional reagents, methods and equipment in the technical field.

[0021] The particle sizes of TiO2 powder, HfO2 powder, V2O5 powder, Ta2O5 powder and WO3 powder used in the examples of the application are all 1-2 μm; the particle size of graphite powder is 100 nm-1 μm, and the particle size of Co powder is 0.4-0.5 μm. Example 1

[0022] 1. TiO2 powder, HfO2 powder, V2O5 powder, Ta2O5 powder, WO3 powder and graphite powder with a molar ratio of 0.225:0.225:0.1125:0.1125:0.1:2 are mixed to prepare a mixed powder; 2. The mixed powder is added into anhydrous ethanol to prepare a slurry by ultrasonic stirring, then silicon nitride (Si3N4) medium balls are added to perform ball milling through a roller ball mill, and the slurry is dried, sieved, and then loaded into an iron mold for dry pressing to prepare a green body; 3. The green body is first vacuumized to a vacuum degree of ≤10 Pa, then heated to 1000 ℃ at a rate of 20 ℃ / min, and then heated to 1600 ℃ at a rate of 10 ℃ / min for 2 h; then cooled to 800 ℃ at a rate of 10 ℃ / min, and then cooled with the furnace, crushed by a high-speed crusher, and sieved through a 100-mesh sieve to obtain (Ti 0.225 Hf 0.225 V 0.225 Ta 0.225 W0.1 High-entropy powder, abbreviated as HEC-W1; 4. The volume ratio of (Ti) is 19:1. 0.225 Hf 0.225 V 0.225 Ta 0.225 W 0.1 High-entropy C powder and Co powder are mixed, anhydrous ethanol is added and ultrasonically stirred to obtain a slurry, which is then ball-milled, dried and sieved by a roller ball mill and then dry-pressed into an iron mold to make a green body. 5. The billet was sintered under uniaxial pressure of 30 MPa at a rate of 100℃ / min to 1650℃ using SPS sintering and held for 10 min. Then, it was symmetrically cooled below 800℃ in the furnace to obtain (Ti) 0.225 Hf 0.225 V 0.225 Ta 0.225 W 0.1 C-Co high-entropy carbide multiphase ceramics. Example 2

[0023] 1. A mixed powder is prepared by mixing TiO2 powder, HfO2 powder, V2O5 powder, Ta2O5 powder, WO3 powder and graphite powder in a molar ratio of 0.2:0.2:0.1:0.1:0.2:3.4; 2. The mixed powder is added to anhydrous ethanol and ultrasonically stirred to obtain a slurry. Then, silicon nitride media balls are added and the mixture is ball-milled, dried, sieved, and then placed into an iron mold for dry pressing to obtain a green blank. 3. First, evacuate the furnace to a vacuum degree ≤10Pa. Heat the green billet to 1000℃ at 20℃ / min, then continue heating at 10℃ / min to 1600℃ and hold for 2 hours. Then, cool it to 800℃ at 10℃ / min and continue cooling in the furnace. After pulverizing with a high-speed pulverizer and passing through a 100-mesh sieve, (Ti) is obtained. 0.2 Hf 0.2 V 0.2 Ta 0.2 W 0.2 High-entropy powder, abbreviated as HEC-W2; 4. Mix (Ti) in a volume ratio of 19:1 0.2 Hf 0.2 V 0.2 Ta 0.2 W 0.2 High-entropy C powder and Co powder are mixed and ultrasonically stirred with anhydrous ethanol to prepare a slurry. Then, silicon nitride media balls are added, and the mixture is ball-milled, dried, sieved, and then loaded into an iron mold and dry-pressed into a blank. 5. The green body is subjected to SPS sintering at 30 MPa uniaxial pressure, with temperature rising to 1650 ℃ at 100 ℃ / min and holding for 10 min, and then symmetrical temperature reduction below 800 ℃ with furnace cooling, to obtain (Ti 0.2 Hf 0.2 V 0.2 Ta 0.2 W 0.2 )C-Co high-entropy carbide composite ceramic. Example 3

[0024] 1. TiO2 powder, HfO2 powder, V2O5 powder, Ta2O5 powder, WO3 powder and graphite powder in a molar ratio of 0.175:0.175:0.0875:0.0875:0.3:3.475 are mixed to obtain mixed powder; 2. The mixed powder is added into anhydrous ethanol for ultrasonic stirring to obtain slurry, and then silicon nitride medium balls are added for ball milling by a roller ball mill, and the slurry is dried, sieved and then loaded into an iron mold for dry pressing into a green body; 3. The green body is first vacuumized to a vacuum degree of ≤10 Pa, and then heated to 1000 ℃ at 20 ℃ / min, and then heated to 1600 ℃ at 10 ℃ / min and held for 2 h, and then cooled to 800 ℃ at 10 ℃ / min and then cooled with the furnace, and then crushed by a high-speed crusher and sieved through a 100-mesh sieve, to obtain (Ti 0.175 Hf 0.175 V 0.175 Ta 0.175 W 0.3 )C high-entropy powder, abbreviated as HEC-W3; 4. The (Ti 0.175 Hf 0.175 V 0.175 Ta 0.175 W 0.3 )C high-entropy powder and Co powder in a volume ratio of 19:1 are mixed, added into anhydrous ethanol for ultrasonic stirring to obtain slurry, and then silicon nitride medium balls are added for ball milling by a roller ball mill, and the slurry is dried, sieved and then loaded into an iron mold for dry pressing into a green body; 5. The green body is subjected to SPS sintering at 10 MPa uniaxial pressure, with temperature rising to 1600 ℃ at 100 ℃ / min and holding for 10 min, and then symmetrical temperature reduction below 800 ℃ with furnace cooling, to obtain (Ti 0.175 Hf 0.175 V 0.175 Ta 0.175 W 0.3 )C-Co high-entropy carbide composite ceramic.

[0025] Comparative Example 1 1. TiO2 powder, HfO2 powder, V2O5 powder, Ta2O5 powder and graphite powder with a molar ratio of 0.25:0.25:0.125:0.125:3.25 are mixed to obtain a mixed powder; 2. The mixed powder is added into anhydrous ethanol to obtain a slurry by ultrasonic stirring, and then silicon nitride medium balls are added to be ball milled by a roller ball mill, dried, sieved, and then loaded into an iron mold to be dry-pressed into a green body; 3. The green body is first vacuumized to a vacuum degree of ≤10 Pa, and then heated to 1000℃ at a rate of 20℃ / min, and then heated to 1600℃ at a rate of 10℃ / min and kept for 2 h, and then cooled to 800℃ at a rate of 10℃ / min, and then cooled with the furnace, and then crushed by a high-speed crusher and sieved through a 100-mesh sieve to obtain (Ti 0.25 Hf 0.25 V 0.25 Ta 0.25 )C carbide powder, which is abbreviated as HEC-W0; 4. The (Ti 0.25 Hf 0.25 V 0.25 Ta 0.25 )C carbide powder and Co powder with a volume ratio of 19:1 are mixed, and then anhydrous ethanol is added to obtain a slurry by ultrasonic stirring, and then silicon nitride medium balls are added to be ball milled by a roller ball mill, dried, sieved, and then loaded into an iron mold to be dry-pressed into a green body; 5. The green body is sintered by SPS at a uniaxial pressure of 30 MPa and a heating rate of 100℃ / min to 1650℃ and kept for 10 min, and then cooled symmetrically below 800℃ with the furnace to obtain (Ti 0.25 Hf 0.25 V 0.25 Ta 0.25 )C-Co carbide composite ceramic.

[0026] Figure 1 XRD patterns of the (Ti, Hf, V, Ta, W)C high-entropy carbide powders with different W contents prepared in Examples 1-3 and the carbide powder of Comparative Example 1. Among them, HEC-W0 is the quaternary carbide powder without W element of Comparative Example 1, HEC-W1 is the high-entropy carbide powder (Ti 0.225 Hf 0.225 V 0.225 Ta 0.225 W 0.1 )C of Example 1, HEC-W2 is the high-entropy carbide powder (Ti 0.2 Hf 0.2 V 0.2 Ta 0.2 W 0.2 )C of Example 2, and HEC-W3 is the high-entropy carbide powder (Ti0.175 Hf 0.175 V 0.175 Ta 0.175 W 0.3 C. From Figure 1 As can be seen, the XRD pattern of the quaternary carbide powder in Comparative Example 1 shows a bimodal structure, indicating that it did not form a high-entropy phase, but existed in the form of quaternary carbides. Further addition of Co followed by SPS sintering prepared a high-entropy carbide multiphase ceramic with a hardness of 23.9 ± 0.17 GPa and a fracture toughness of 3.57 ± 0.07 MPa·m. 1 / 2 When machining ductile iron, the cutting length was 8163 m. Example 1: High-entropy carbide powder (Ti 0.225 Hf 0.225 V 0.225 Ta 0.225 W 0.1 The XRD pattern of C showed that it formed a single solid solution high-entropy phase. The C peak was due to the formation of carbon vacancies during the powder synthesis process, resulting in excess C. Further addition of Co followed by SPS sintering produced a high-entropy carbide multiphase ceramic with a hardness of 24.5 ± 0.17 GPa and a fracture toughness of 4.17 MPa·m. 1 / 2 When machining ductile iron, the cutting length was 10740 m. Examples 2 and 3 also formed a single solid solution high-entropy phase. The hardness of the high-entropy carbide multiphase ceramics prepared from these examples were 25.8 ± 0.22 GPa and 26.2 ± 0.31 GPa, respectively, and the fracture toughness was 4.7 ± 0.10 MPa·m, respectively. 1 / 2 and 5.7±0.04MPa·m 1 / 2 The cutting lengths for cutting ductile iron were 14372 m and 16170 m, respectively. From a mechanical and cutting performance perspective, the high-entropy carbide multiphase ceramics with different W contents in Examples 1-3 were superior to those in Comparative Example 1 (Ti). 0.25 Hf 0.25 V 0.25 Ta 0.25 C-Co quaternary carbide multiphase ceramics are produced by the addition of W, which promotes the transformation from quaternary carbides to high-entropy carbides, specifically in solid solution strengthening.

[0027] The high-entropy carbide multiphase ceramic (Ti, Hf, V, Ta, W)C-Co prepared by this invention, by adjusting the W content during sintering, promotes the solid solution process, resulting in high hardness and high toughness of the high-entropy carbide multiphase ceramic, while significantly improving its machinability. The Vickers hardness of this high-entropy carbide multiphase ceramic is 25~26.5 GPa, and its fracture toughness is 4~5.7 MPa·m. 1 / 2The service life of the cutting nodular cast iron is 1673-16170 m, and the cutting tool can be applied to the field of preparing cutting tools.

[0028] The above examples are the preferred embodiments of the present application, but the embodiments of the present application are not limited to the above examples, and any changes, modifications, substitutions, combinations and simplifications made without departing from the spirit and principles of the present application should be equivalent replacement methods, and are included in the protection scope of the present application.

Claims

1. A high-entropy carbide multiphasic ceramic, characterized in that, The high-entropy carbide composite ceramic has a molecular formula of (Ti x Hf y V z Ta m W n )C-Co, wherein x+y+z+m+n=1, x=0.175~0.25, y=0.175~0.25, z=0.175~0.25, m=0.175~0.25, n=0.1~0.3, TiO2 powder, HfO2 powder, V2O5 powder, Ta2O5 powder, WO3 powder and graphite powder are mixed to obtain a mixed powder, the mixed powder is added into anhydrous ethanol for stirring to obtain a slurry, the slurry is subjected to ball milling, drying and sieving, and then dry-pressed into a green body, the green body is sintered at 1500~1600℃ under vacuum without pressure to obtain a high-entropy powder; the high-entropy powder and Co powder are mixed, and anhydrous ethanol is added for ultrasonic stirring to obtain a slurry, the slurry is subjected to ball milling, drying and sieving, and then dry-pressed into a compact body; and the compact body is sintered by SPS at 1600~1700℃ under a uniaxial pressure of 25~30 MPa.

2. The high-entropy carbide multiphasic ceramic of claim 1, wherein, The high-entropy carbide composite ceramic has a Vickers hardness of 25-26.5 GPa and a fracture toughness of 4-5.7 MPa·m 1 / 2 The service life for cutting cast iron is 1673-16170 m.

3. The high-entropy carbide multiphasic ceramic of claim 1, wherein, The particle size of the TiO2 powder, HfO2 powder, V2O5 powder, Ta2O5 powder and WO3 powder is 1-2 μm; the particle size of the graphite powder is 100 nm-1 μm, and the particle size of the Co powder is 0.4-0.5 μm.

4. The high-entropy carbide composite ceramic of claim 1, wherein, The volume ratio of the high-entropy powder to the Co powder is (47-48):(2-3).

5. The high entropy carbide composite ceramic of claim 1, wherein, The molar ratio of the TiO2 powder, HfO2 powder, V2O5 powder, Ta2O5 powder, WO3 powder and graphite powder is (0.175-1):(0.175-1):(0.0875-0.5):(0.0875-0.5):(0.1-0.3):(2-4).

6. The method of claim 1-5, wherein the high-entropy carbide composite ceramic is prepared by the steps of: The method comprises the following steps: S1. mixing the TiO2 powder, HfO2 powder, V2O5 powder, Ta2O5 powder, WO3 powder and graphite powder to obtain a mixed powder; S2. adding the mixed powder into anhydrous ethanol to obtain a slurry by ultrasonic stirring, then performing ball milling, drying, sieving and dry pressing to obtain a green body, and then performing pressureless sintering on the green body under vacuum at a temperature of 1500-1600℃ to obtain a high-entropy powder; S3. mixing the high-entropy powder and Co powder into anhydrous ethanol to obtain a slurry by ultrasonic stirring, then performing ball milling, drying, sieving and dry pressing to obtain a green body; S4. The blank is sintered by SPS at uniaxial pressure of 25-30 MPa and temperature of 1600-1700 ℃, and high-entropy carbide composite ceramics with molecular formula (Ti x Hf y V z Ta m W n )C-Co are prepared.

7. The method of claim 6, wherein the high-entropy carbide multiphasic ceramic is prepared by the steps of: mixing the carbide-forming elements in a powder form to form a mixture; and sintering the mixture to form the high-entropy carbide multiphasic ceramic. In step S2, the rotating speed of the ball milling is 100-300 r / min, the ball milling time is 18-36 h, the drying temperature is 60-80℃, and the drying time is 12-24 h.

8. The method of claim 6, wherein the high-entropy carbide multiphasic ceramic is prepared by the steps of: mixing the carbide-forming elements in a powder form to form a mixture; and sintering the mixture to form the high-entropy carbide multiphasic ceramic. In step S2, the vacuum degree of the vacuum is ≤10 Pa, the temperature rising program is first rising at a rate of 15-20℃ / min to 50-1000℃, and then rising at a rate of 8-10℃ / min to 1500-1600℃, and the sintering time is 1.5-2.5 h.

9. The method of claim 6, wherein the high-entropy carbide multiphasic ceramic is prepared by the steps of: mixing the carbide-forming elements in a powder form to form a mixture; and sintering the mixture to form the high-entropy carbide multiphasic ceramic. In step S3, the rotating speed of the ball milling is 100-200 r / min, the ball milling time is 18-36 h, the drying temperature is 60-80℃, and the drying time is 16-24 h; in step S4, the temperature rising rate is 80-100℃ / min, and the holding time is 10-15 min.

10. Use of the high-entropy carbide composite ceramic according to any one of claims 1-5 in the preparation of a cutting tool.

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