High-toughness ZrN-SiAlON composite ceramic as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of high-performance structural ceramics, and discloses a high-toughness ZrN-SiAlON composite ceramic as well as a preparation method and application thereof. The method comprises the following steps: performing ball milling on Si3N4, AlN, Al2O3, Yb2O3 and ZrN powder to obtain slurry, drying the slurry, and sieving the slurry to obtain composite powder; and carrying out spark plasma sintering at the temperature of between 1,800 and 1,850 DEG C and the axial pressure of between 27 and 33 MPa in a nitrogen atmosphere, so as to obtain the ZrN-SiAlON composite ceramic. The composite ceramic is composed of alpha-SiAlON, beta-SiAlON and ZrN, the fracture toughness of the composite ceramic is 6.2-6.6 MPa.m < 1 / 2 >, the hardness of the composite ceramic is 19-20 GPa, and the fracture toughness of the composite ceramic is nearly doubled while the hardness of the composite ceramic is not remarkably reduced compared with that of SiAlON ceramic. The composite ceramic disclosed by the invention has high toughness and excellent comprehensive performance, and is suitable for the fields of aerospace, armor protection, cutting tools and the like.

Description

Technical Field

[0001] This invention belongs to the field of high-performance structural ceramic materials technology, specifically relating to a ZrN-SiAlON multiphase ceramic with high fracture toughness, its preparation method, and its application. Background Technology

[0002] SiAlON ceramics are solid solution materials based on Si3N4. Depending on their crystal structure and the form of elemental solid solution, they are mainly divided into α-SiAlON and β-SiAlON phases. These materials inherit the excellent high-temperature strength, good oxidation resistance, and wear resistance of Si3N4 ceramics. Furthermore, the solid solution of elements such as Al and O improves their sintering performance, showing broad application prospects in high-temperature structural components and cutting tools. However, SiAlON ceramics are essentially still brittle materials, with generally low fracture toughness, typically only 3–4 MPa·m. 1 / 2 This severely limits its reliability in harsh environments such as mechanical shock or thermal shock loads. To improve its toughness, researchers have attempted to introduce second-phase particles, such as SiC, TiC, and TiN, to construct multiphase ceramic systems. Through toughening mechanisms such as crack deflection, crack bridging, and particle pull-out, the fracture toughness of the material can be improved to some extent.

[0003] Among numerous candidate second phases, zirconium nitride (ZrN), as a metal nitride with a face-centered cubic crystal structure, not only possesses a high melting point (approximately 2980℃) and high hardness (approximately 15 GPa), but also exhibits unique metal-covalent mixed bonding characteristics, giving it superior toughness compared to most ceramics. Furthermore, ZrN exhibits good chemical stability and corrosion resistance at high temperatures. These properties theoretically make it very suitable as a toughening phase for SiAlON ceramics. However, ZrN-SiAlON multiphase ceramics encounter the following problems during SPS sintering: under normal pressure or without special protection, ZrN is prone to oxidation and thermal decomposition at high temperatures (especially >1500℃), leading to uncontrolled phase composition and deterioration of material properties; obtaining high-density SiAlON ceramics requires holding at higher sintering temperatures for longer periods, which exacerbates the decomposition of ZrN at high temperatures. However, lowering the SPS sintering temperature or shortening the holding time to protect ZrN can affect the transformation from α to β-SiAlON phases, preventing the formation of a stable microstructure. The introduction of the second phase often sacrifices one property while improving another. Therefore, the key to achieving its engineering applications lies in how to significantly improve toughness while maintaining high hardness through ZrN introduction. Preliminary studies indicate that direct ZrN addition, if the sintering process is improper, may improve toughness but drastically reduce hardness, making it difficult to meet the comprehensive performance requirements of practical applications. Therefore, developing a stable method for preparing ZrN-SiAlON multiphase ceramics is crucial for their practical application. Summary of the Invention

[0004] To address the challenge of achieving both high hardness and high toughness in Si3N4 ceramics under SPS sintering conditions, this invention provides a method for preparing high-toughness ZrN-SiAlON multiphase ceramics. This method prepares stable ZrN-SiAlON multiphase ceramics with high fracture toughness by controlling the SPS sintering parameters.

[0005] Another objective of this invention is to prepare high-toughness ZrN-SiAlON multiphase ceramics using the above method.

[0006] Another object of the present invention is to utilize the above-mentioned high-toughness ZrN-SiAlON multiphase ceramic.

[0007] The technical solution adopted by this invention to solve its technical problem is: A method for preparing a high-toughness ZrN-SiAlON multiphase ceramic includes the following steps: S1. The mixture of Si3N4 powder, AlN powder, Al2O3 powder, Yb2O3 powder and ZrN powder is mixed with anhydrous ethanol and then ball-milled to obtain a uniform slurry. S2. After drying the slurry at 60~80℃, sieve it to obtain composite powder; S3. Under a nitrogen atmosphere, the composite powder is subjected to an axial pressure of 27~33MPa and heated to 1800~1850℃ for discharge plasma sintering to obtain high-toughness ZrN-SiAlON composite ceramic.

[0008] Preferably, the purity of Si3N4 powder, AlN powder, Al2O3 powder, Yb2O3 powder and ZrN powder in step S1 is all above 99%, the ball milling medium is Si3N4 balls, the mass ratio of balls to material is (4~5):1, the ball milling speed is 180~200 rpm, and the ball milling time is 18~24h.

[0009] Preferably, in step S1, the mass ratio of Si3N4 powder, AlN powder, Al2O3 powder, Yb2O3 powder and ZrN powder is 22.792:3.815:0.205:3.189:(3.24~20.5), the amount of ZrN powder is 20~25 vol% of the composite ceramic powder, and the mass ratio of the mixed powder and anhydrous ethanol is 1:(2~3).

[0010] Preferably, the drying time in step S2 is 18-24 hours, and the particle size of the sieve is 80-100 mesh.

[0011] Preferably, the procedure for spark plasma sintering in step S3 is as follows: first, the temperature is increased to 300°C at a rate of 25-30°C / min and held for 1-2 minutes; then, the temperature is increased to 800°C at a rate of 80-100°C / min and held for 1-2 minutes; then, the temperature is increased to 1200°C at a rate of 80-100°C / min and held for 1-2 minutes; then, the temperature is increased to 1800-1850°C at a rate of 80-100°C / min and held for 10 minutes; then, the temperature is decreased to 1200°C at a rate of 80-100°C / min; then, the temperature is decreased to 800°C at a rate of 80-100°C / min; and finally, the temperature is cooled with the furnace.

[0012] A high-toughness ZrN-SiAlON multiphase ceramic was prepared by the method described above.

[0013] Preferably, the multiphase ceramic is composed of α-SiAlON, β-SiAlON and ZrN, wherein the molecular formula of α-SiAlON is Yb. 0.33 Si 10 Al 12 O1N 15 The molecular formula of β-SiAlON is Si5.5 Al 0.5 O 0.5 N 7.5 .

[0014] Preferably, the volume ratio of α-SiAlON, β-SiAlON and ZrN is (9~11):(4~5):(5~6).

[0015] Preferably, the fracture toughness of the multiphase ceramic is 6.2~6.6 MPa·m. 1 / 2 Its hardness is 19.3~20 GPa.

[0016] The high-toughness ZrN-SiAlON multiphase ceramics described herein are used in high-temperature aerospace components, cutting tools, protective armor, or high-temperature structural parts.

[0017] Compared with the prior art, the present invention has the following beneficial effects: 1. The ZrN-SiAlON multiphase ceramic of this invention, by introducing 25~30 vol% ZrN as a second phase, effectively hinders crack propagation and significantly improves the fracture toughness of SiAlON ceramic, from 3.11 MPa·m. 1 / 2 Increased to 6.2~6.6 MPa·m 1 / 2 The increase was over 99%; the hardness of ZrN-SiAlON multiphase ceramics was 19.3~20 GPa, which was not significantly reduced compared to the hardness of SiAlON ceramics without ZrN (21.62±0.57 GPa), maintaining good comprehensive mechanical properties.

[0018] 2. The multiphase ceramic prepared by this invention possesses high toughness and excellent comprehensive properties, with a fracture toughness reaching 6.19 ± 0.29 MPa·m. 1 / 2 Compared to the fracture toughness of SiAlON ceramics (3.11±0.12MPa·m), 1 / 2 The hardness is nearly doubled; compared with the hardness without ZrN (21.62±0.57GPa), the hardness (19.30±0.35GPa) is not significantly reduced, making it suitable for high-end fields such as aerospace, armor protection, and cutting tools.

[0019] 3. This invention utilizes SPS rapid sintering to suppress excessive grain growth, ensuring uniform distribution of the ZrN phase and interfacial bonding strength, forming a synergistic reinforcement structure of α-SiAlON, β-SiAlON and ZrN phases; 4. The ZrN-SiAlON multiphase ceramic of the present invention also possesses high toughness (6.2~6.6 MPa·m). 1 / 2 It is suitable for manufacturing high-temperature components, cutting tools, protective armor, or high-temperature structural parts for aerospace applications. Attached Figure Description

[0020] Figure 1 The discharge plasma sintering temperature gradient diagram of the ZrN-SiAlON multiphase ceramic prepared in Example 1; Figure 2 SEM image of the ZrN-SiAlON composite ceramic of Example 1; Figure 3 Crack extension diagram of ZrN-SiAlON multiphase ceramic in Example 1; Figure 4 The image shows a SEM image of the ZrN-SiAlON composite ceramic from Example 2. Detailed Implementation

[0021] The present invention will be further described below with reference to specific embodiments, but these should not be construed as limiting the invention. Unless otherwise specified, the technical means used in the embodiments are conventional means well known to those skilled in the art. Unless otherwise specified, the reagents, methods, and equipment used in the present invention are conventional reagents, methods, and equipment in this technical field.

[0022] The purity of the Si3N4 powder, AlN powder, Al2O3 powder, and Yb2O3 powder used in the embodiments of the present invention is all above 99%.

[0023] Example 1 1. Si3N4 powder, AlN powder, Al2O3 powder, and Yb2O3 powder were mixed in a mass ratio of 76:12.7:0.68:10.62, and then 20 vol% of ZrN powder was added to the above mixed powder. Anhydrous ethanol was used as the solvent, and Si3N4 balls were used as the ball milling medium. The mass ratio of ball to powder was 4:1. The mixture was ball milled in a roller ball mill at 200 rpm for 24 h to obtain a slurry. 2. The slurry is evaporated in a rotary evaporator to remove anhydrous ethanol, then placed in an oven and dried at 80°C for 2 hours. The slurry is then sieved through a 100-mesh sieve to obtain a uniform powder with a particle size of 0.5~1μm. 3. The powder is loaded into a graphite mold and placed in an SPS furnace. Under a nitrogen atmosphere, an axial pressure of 30 MPa is applied, and the temperature is increased to 300°C at a rate of 25-30°C / min, held for 1-2 min, then increased to 800°C at 100°C / min, held for 1-2 min, then increased to 1200°C at 100°C / min, held for 1-2 min, then increased to 1800°C at 100°C / min, held for 10 min, then decreased to 1200°C at 100°C / min, then decreased to 800°C at 100°C / min, and finally cooled in the furnace to obtain ZrN-SiAlON multiphase ceramic. This multiphase ceramic is composed of α-SiAlON (Yb) in a volume ratio of 55:20:25. 0.33 Si 10 Al 12O1N 15 ), β-SiAlON (Si 5.5 Al 0.5 O 0.5 N 7.5 The ZrN-SiAlON multiphase ceramic obtained in this embodiment is composed of ZrN and ZrN. The fracture toughness of the ZrN-SiAlON multiphase ceramic is 6.3 MPa·m. 1 / 2 Its hardness is 19.30 GPa.

[0024] Figure 1 The image shows the plasma discharge temperature gradient of the ZrN-SiAlON multiphase ceramic prepared in Example 1; from... Figure 1 It can be seen that the density of high-toughness ZrN-SiAlON multiphase ceramics prepared in the sintering range of 1800~1850℃ is above 99.7%. Figure 2 This is a SEM image of the ZrN-SiAlON multiphase ceramic from Example 1. The gray equiaxed structures represent α-SiAlON, and the black rod-shaped structures represent β-SiAlON. From... Figure 2 It can be seen that ZrN-SiAlON multiphase ceramics not only contain α-SiAlON phase but also β-SiAlON phase, indicating that the addition of 20 vol% ZrN will produce β-SiAlON phase. Figure 3 This is a crack propagation diagram of the ZrN-SiAlON multiphase ceramic of Example 1. From... Figure 3 It is known that the formation of the β-SiAlON phase will hinder the crack propagation of ZrN-SiAlON composite ceramics.

[0025] Example 2 1. Si3N4 powder, AlN powder, Al2O3 powder, and Yb2O3 powder were mixed in a mass ratio of 76:12.7:0.68:10.62, and then 25 vol% of ZrN powder was added to the above mixed powder. Anhydrous ethanol was used as the solvent, and Si3N4 balls were used as the ball milling medium. The mass ratio of ball to powder was 4:1. The mixture was ball milled in a roller ball mill at 200 rpm for 24 h to obtain a slurry. 2. The slurry was evaporated in a rotary evaporator to remove anhydrous ethanol, and then dried in an oven at 80°C for 2 hours. The slurry was then sieved through a 100-mesh sieve to obtain a uniform powder with a particle size of 0.5~1μm. 3. The powder is loaded into a graphite mold and placed in an SPS furnace. Under a nitrogen atmosphere, an axial pressure of 30 MPa is applied, and the temperature is increased to 300°C at a rate of 25-30°C / min, held for 1-2 min, then increased to 800°C at a rate of 80-100°C / min, held for 1-2 min, then increased to 1200°C at a rate of 80-100°C / min, held for 1-2 min, then increased to 1800°C at a rate of 80-100°C / min, held for 10 min, then decreased to 1200°C at a rate of 80-100°C / min, then decreased to 800°C at a rate of 80-100°C / min, and finally cooled in the furnace to obtain ZrN-SiAlON multiphase ceramic. This multiphase ceramic is composed of α-SiAlON, β-SiAlON and ZrN in a volume ratio of 45:25:30. The fracture toughness of the ZrN-SiAlON composite ceramic obtained in this embodiment is 6 MPa·m. 1 / 2 Its hardness is 18.45 GPa.

[0026] Comparative Example 1 1. Si3N4 powder, AlN powder, Al2O3 powder, and Yb2O3 powder in a mass ratio of 76:12.70:0.68:10.62 were ball-milled in a roller ball mill at 200 rpm for 24 h with anhydrous ethanol as the solvent and Si3N4 balls as the ball-to-material media, with a ball-to-material mass ratio of 4:1, to obtain a slurry. 2. The slurry is evaporated in a rotary evaporator to remove anhydrous ethanol, then placed in an oven and dried at 80°C for 2 hours. The slurry is then sieved through a 100-mesh sieve to obtain a uniform powder with a particle size of 0.5~1μm. 3. The powder is loaded into a graphite mold and placed in an SPS furnace. Under a nitrogen atmosphere, an axial pressure of 30 MPa is applied, and the temperature is increased to 300°C at a rate of 25-30°C / min, held for 1-2 minutes, then increased to 800°C at 100°C / min, held for 1-2 minutes, then increased to 1200°C at 100°C / min, held for 1-2 minutes, then increased to 1800°C at 100°C / min, held for 10 minutes, then decreased to 1200°C at 100°C / min, then decreased to 800°C at 100°C / min, and finally cooled in the furnace to obtain α-SiAlON phase ceramic with the molecular formula Yb. 0.33 Si 10 Al 12 O1N 15 .

[0027] Figure 4 SEM images of α-SiAlON phase ceramics from Comparative Example 1; from Figure 4It can be seen that the α-SiAlON phase ceramic only contains α-SiAlON, indicating that without the addition of ZrN, only the α-SiAlON phase is produced. Its hardness is 21.62±0.57 GPa, and its fracture toughness is only 3.11 MPa·m. 1 / 2 .

[0028] The ZrN-SiAlON multiphase ceramic of the present invention effectively inhibits crack propagation and significantly improves the fracture toughness of SiAlON ceramic by introducing 25~30 vol% ZrN as a second phase. The fracture toughness of the multiphase ceramic is 6.2~6.6 MPa·m. 1 / 2 With a hardness of 19.3~20GPa, it can be used in the manufacture of high-temperature aerospace components, cutting tools, protective armor, or high-temperature structural parts.

[0029] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A method for preparing a high toughness ZrN-SiAlON composite ceramic, characterized in that, The method comprises the following steps: S1. adding mixed powders of Si3N4 powder, AlN powder, Al2O3 powder, Yb2O3 powder and ZrN powder into anhydrous ethanol, and performing roller ball milling to obtain a uniform slurry; S2. drying the slurry at 60-80℃ and then sieving to obtain a composite powder; S3. under a nitrogen atmosphere, applying an axial pressure of 27-33 MPa to the composite powder, and heating to 1800-1850℃ to perform discharge plasma sintering to obtain a high-toughness ZrN-SiAlON composite ceramic.

2. The method of claim 1, wherein the high toughness ZrN-SiAlON composite ceramic is prepared by the steps of: mixing a ZrN powder and a SiAlON powder to form a mixture; and sintering the mixture at a temperature of 1600°C to 1800°C for 1 to 5 hours in a nitrogen atmosphere. The purity of the Si3N4 powder, AlN powder, Al2O3 powder, Yb2O3 powder and ZrN powder in step S1 is all above 99%, the medium for the ball milling is Si3N4 balls, the mass ratio of the balls to the material is (4-5):1, the speed of the ball milling is 180-200 rpm, and the time of the ball milling is 18-24 h.

3. The method of claim 1, wherein the high toughness ZrN-SiAlON composite ceramic is prepared by the steps of: preparing a mixture of ZrN and SiAlON powders; and sintering the mixture at a temperature of 1600-1800°C in a nitrogen atmosphere. The mass ratio of the Si3N4 powder, AlN powder, Al2O3 powder, Yb2O3 powder and ZrN powder in step S1 is 22.792:3.815:0.205:3.189:(3.24-20.5), the amount of the ZrN powder is 20-25 vol% of the composite ceramic powder, and the mass ratio of the mixed powder to anhydrous ethanol is 1:(2-3).

4. The method for preparing high-toughness ZrN-SiAlON multiphase ceramics according to claim 1, characterized in that, The time of the drying in step S2 is 18-24 h, and the particle size of the sieve is 80-100 mesh.

5. The method for preparing high-toughness ZrN-SiAlON multiphase ceramics according to claim 1, characterized in that, The procedure of the discharge plasma sintering in step S3 is as follows: first, heating at a rate of 25-30℃ / min to 300℃, maintaining for 1-2 min, then heating at a rate of 80-100℃ / min to 800℃, maintaining for 1-2 min, then heating at a rate of 80-100℃ / min to 1200℃, maintaining for 1-2 min, then heating at a rate of 80-100℃ / min to 1800-1850℃, maintaining for 10 min, then cooling at a rate of 80-100℃ / min to 1200℃, then cooling at a rate of 80-100℃ / min to 800℃, and finally cooling with the furnace.

6. A high toughness ZrN-SiAlON composite ceramic, characterized in that, The ZrN-SiAlON composite ceramic is prepared by the method of any one of claims 1-5.

7. The ZrN-SiAlON composite ceramic according to claim 6, characterized in that The composite ceramic consists of α-SiAlON, β-SiAlON and ZrN, the α-SiAlON has a molecular formula of Yb 0.33 Si 10 Al 12 O1N 15 , the β-SiAlON has a molecular formula of Si 5.5 Al 0.5 O 0.5 N 7.5 .

8. The ZrN-SiAlON composite ceramic according to claim 7, characterized in that The volume ratio of the α-SiAlON, β-SiAlON and ZrN is (9-11):(4-5):(5-6).

9. The ZrN-SiAlON composite ceramic of claim 6, wherein, The fracture toughness of the composite ceramic is 6.2-6.6 MPa·m 1 / 2 , and the hardness is 19.3-20 GPa.

10. Use of the high-toughness ZrN-SiAlON composite ceramic of any one of claims 6-9 in preparing aerospace high-temperature components, cutting tools, protective armor or high-temperature structural parts.

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