Small-particle-size low-oxygen ZrB-SiC complex-phase powder, one-step controllable synthesis method thereof and application of powder in high-performance ceramics

Abstract

The invention discloses small-particle-size low-oxygen ZrB-SiC complex-phase powder, a one-step controllable synthesis method thereof and application of the powder in high-performance ceramics, and belongs to the technical field of ultra-high-temperature ceramic materials. According to the method, ZrO, BC, elemental Si and activated carbon are used as raw materials, and the ZrB-SiC complex-phase powder is prepared through an optimized boron-carbon thermal reduction method. The core innovation point is that the specific raw material ratio design is as follows: n (ZrO): n (BC): n (Si): n (C) = 3: (1.65-1.95): (0.5-1.0): (4.95-6.05), the most preferable ratio is 3: 1.8: 1: 5.5, and heat preservation is performed for 60 minutes at 1500 DEG C in an inert atmosphere. The design effectively compensates volatilization of intermediate phase BO, and ensures complete reaction. The prepared multiphase powder has the prominent advantages of small particle size (D100lt, 0.71 [mu] m), low oxygen content, high purity and accurate regulation and control of the ratio of two phases, and ZrB and SiC two-phase interfaces in the powder are in semi-coherent combination. The high-performance ZrB-SiC composite ceramic can be prepared by using the self-made powder as a raw material and adopting spark plasma sintering (SPS), and the relative density of the high-performance ZrB-SiC composite ceramic is up to 99.24% or above.

Description

Technical Field

[0001] This invention relates to the field of ultra-high temperature ceramic materials technology, specifically to a small-particle-size, low-oxygen ZrB2-SiC multiphase powder, its one-step controllable synthesis method, and its application in high-performance ceramics. Background Technology

[0002] ZrB2-SiC ultra-high temperature ceramics are widely considered key candidate materials for thermal protection components in extreme hot service environments such as next-generation hypersonic vehicles, atmospheric reentry vehicles, and rocket propulsion systems due to their high melting point (approximately 3250℃), high thermal conductivity (approximately 60 W / (m·K)), and excellent high-temperature strength and oxidation resistance. However, the performance of ceramic materials is highly dependent on the quality of their precursor powder. To obtain ZrB2-SiC multiphase ceramics with high density and excellent comprehensive properties, it is necessary to obtain high-quality ZrB2-SiC multiphase powders that possess small particle size (to promote sintering activity), low oxygen content (to avoid the formation of brittle oxide grain boundary phases), high purity, and controllable two-phase ratio. These characteristics of the powder are decisive factors affecting the final sintering densification behavior, microstructure, and even mechanical and oxidation resistance properties of the ceramic.

[0003] Currently, methods for preparing ZrB2-SiC multiphase powder mainly include polymer precursor methods, self-propagating high-temperature synthesis methods, and various thermal reduction methods. Among them, the boron-carbon thermal reduction method has attracted attention due to its potential advantages such as wide availability of raw materials, low cost, and ease of large-scale production. However, existing boron-carbon thermal reduction technologies have significant limitations and inherent defects, making it difficult to ideally meet the aforementioned core requirements:

[0004] Large particle size and uneven morphology of the products: Existing methods generally suffer from high reaction temperatures and long reaction times, leading to excessive grain growth. For example, Cao et al. reacted zirconium silicate and other raw materials at 1650℃ for 2 hours, obtaining powders with an average particle size of 10-20 micrometers; although Zeng et al.'s microwave molten salt method reduced the reaction temperature to 1200℃, the average particle size of the product was still as high as about 38 micrometers. In addition, the research of Xie et al. showed that if SiO2 is used instead of elemental Si as the silicon source, it is easy to cause ZrO2 residue in the product, and the powder morphology exhibits an uneven state with both columnar and granular shapes.

[0005] Inaccurate process control and impurity introduction: Existing research lacks systematic optimization of key process parameters (such as precise metering of B4C excess compensation for B2O3 volatilization, balance of carbon source activity and total amount, and coordinated control of reaction temperature and time). For example, insufficient B4C content leads to incomplete ZrO2 reduction, while excess may introduce unreacted B4C impurities. Simultaneously, some additives introduced to lower reaction temperature (such as molten salts) can easily introduce difficult-to-remove impurity phases, impairing powder purity.

[0006] The correlation between powder properties and ceramic properties is weak: Most studies focus on powder synthesis itself and fail to fully demonstrate the advantages of the prepared powder in sintering into high-performance ceramics. There is a lack of complete chain verification from "powder properties" to "ceramic properties". In particular, there are insufficient reports on obtaining ceramics with near-complete density (>99%) and excellent mechanical properties using self-made powders.

[0007] In summary, a long-standing but unresolved technical problem for those skilled in the art is how to synthesize ZrB2-SiC multiphase powder in one step using an economical, efficient, and highly controllable process that simultaneously meets the stringent requirements of small particle size (submicron level), low oxygen content, high purity, and precisely controllable phase ratio, and how to verify its practical application in the preparation of high-performance ZrB2-SiC multiphase ceramics, thereby breaking through the raw material bottleneck in the current development of high-quality ZrB2-SiC ultra-high temperature ceramics. This also constitutes the starting point for the completion of this invention and the core technical obstacle to be overcome.

[0008] To this end, we propose a small-particle-size, low-oxygen ZrB2-SiC multiphase powder, its one-step controllable synthesis method, and its application in high-performance ceramics. Summary of the Invention

[0009] To achieve the above objectives, the present invention provides the following technical solution: a small-particle-size, low-oxygen ZrB2-SiC multiphase powder and its one-step controllable synthesis method, characterized by comprising the following steps:

[0010] Raw material preparation steps: Provide zirconium source, boron source, silicon source and carbon source, wherein the zirconium source is ZrO2 powder, the boron source is B4C powder, the silicon source is elemental Si powder and the carbon source is activated carbon powder;

[0011] Preparation steps: Weigh and mix the raw materials in a molar ratio of n(ZrO2):n(B4C):n(Si):n(C) = 3:(1.65~1.95):(0.5~1.0):(4.95~6.05);

[0012] Mixing step: The weighed raw materials are mechanically mixed to obtain a uniformly mixed raw material powder;

[0013] Reaction steps: The mixed raw material powder is placed in a reaction device under an inert atmosphere and subjected to a boron-carbon thermal reduction reaction through a heat treatment process to synthesize the ZrB2-SiC multiphase powder; the heat treatment process includes: heating to 1200-1300℃ at a first heating rate, then heating to the final reaction temperature of 1400-1600℃ at a second heating rate lower than the first heating rate, and holding at the final reaction temperature for 30-120 minutes;

[0014] Post-processing steps: After the reaction is complete, the product is cooled to room temperature in the furnace to obtain the ZrB2-SiC multiphase powder;

[0015] The maximum particle size D100 of the ZrB2-SiC multiphase powder is less than 0.71 μm, and its phase composition, as determined by X-ray diffraction analysis, contains only ZrB2 and β-SiC phases.

[0016] Preferably, in the batching step, the molar ratio of the raw materials is preferably n(ZrO2): n(B4C): n(Si): n(C) = 3: 1.8: 1: 5.5.

[0017] Preferably, in the reaction step, the final reaction temperature is preferably 1500°C, and the holding time is preferably 60 minutes.

[0018] Preferably, the first heating rate is 3-8℃ / min, and the second heating rate is 1-3℃ / min.

[0019] Preferably, in the mixing step, the mechanical mixing includes premixing in an agate mortar, followed by dry ball milling in a planetary ball mill at a speed of 150-250 rpm for 6-15 hours.

[0020] Preferably, the inert atmosphere is a high-purity argon atmosphere with a flow rate of 30-50 mL / min and a purity of not less than 99.999%.

[0021] Preferably, by adjusting the molar amount of n(Si) in the ingredients, the molar ratio of ZrB2 to SiC in the prepared ZrB2-SiC multiphase powder can be precisely controlled within the range of 2:1 to 4:1.

[0022] Preferably, the multiphase powder is composed of ZrB2 phase and β-SiC phase, with a maximum particle size D100 of less than 0.71 μm, an average particle size of 0.1-0.6 μm, and an oxygen content of less than 1.0 wt%.

[0023] A method for preparing high-performance ZrB2-SiC multiphase ceramics, characterized by comprising the following steps:

[0024] The small-particle-size, low-oxygen ZrB2-SiC multiphase powder as described in claim 8 is provided as a raw material;

[0025] The composite powder is subjected to spark plasma sintering. The sintering process is as follows: in a vacuum environment, the temperature is raised to 1650-1750℃ at a heating rate of 80-120℃ / min, while an axial pressure of 25-35 MPa is applied, and the temperature is held at the highest temperature for 3-8 minutes.

[0026] After sintering, the high-performance ZrB2-SiC multiphase ceramic is obtained by cooling in the furnace.

[0027] Preferably, the relative density of the multiphase ceramic is not less than 99%, the Vickers hardness is not less than 17.5 GPa, the flexural strength is not less than 450 MPa, and the fracture toughness is not less than 4.8 MPa·m¹ / ². The microstructure of the multiphase ceramic is a uniform fine-grained structure, and its fracture morphology shows that the fracture mode is a mixed mode of transgranular fracture and intergranular fracture. Its toughening mechanism includes crack deflection and crack branching caused by SiC particles.

[0028] Compared with existing technologies, this invention provides a small-particle-size, low-oxygen ZrB2-SiC multiphase powder, its one-step controllable synthesis method, and its application in high-performance ceramics, which has the following beneficial effects:

[0029] 1. This invention relates to a small-particle-size, low-oxygen ZrB2-SiC multiphase powder and its one-step controllable synthesis method, along with its application in high-performance ceramics. The core of this invention lies in the successful development of a novel one-step synthesis strategy based on boron-carbothermic reduction through systematic optimization of raw material ratios and process parameters. This method uses industrial-grade ZrO2, B4C, elemental Si, and activated carbon as raw materials. Its key innovation lies in precise ratio design: an excess of approximately 20 mol.% B4C is used to compensate for the volatilization of the mesophase B2O3; the carbon source is controlled to the theoretical amount to avoid residue or deficiency; and the ratio of the two phases in the final powder is precisely controlled by adjusting the Si content. Under the optimal process window of holding at 1500℃ for 1 hour, the defects of traditional methods, such as large particle size and easy inclusion of impurity phases, are successfully overcome. This results in the preparation of ZrB2-SiC multiphase powder with small particle size (D100 < 0.71 μm), low oxygen content (no oxygen-containing impurity phases), high purity, and a two-phase ratio that can be flexibly adjusted between 2:1 and 4:1. More importantly, microstructure analysis shows that the two-phase interface exhibits semi-coherent bonding and low lattice distortion rate, which lays an ideal raw material foundation for the preparation of high-performance ceramics.

[0030] 2. This invention relates to a small-particle-size, low-oxygen ZrB2-SiC multiphase powder and its one-step controllable synthesis method, along with its application in high-performance ceramics. The advantages of this invention lie not only in the final powder performance but also in the maturity and reliability of the process itself. Through detailed experimental research, this invention clarifies the key parameters of the entire process, from raw material pretreatment and mixing to staged heating reactions, forming a clear and repeatable operational guideline. This method eliminates expensive or complex raw materials and precursors; all equipment involved is conventional high-temperature furnaces, making the entire process low-cost, simple to operate, and highly promising for industrial application. The entire technical solution forms a complete closed loop from the powder synthesis mechanism (such as the multi-stage formation process revealed by TG-DSC analysis) to the final product performance characterization (XRD, SEM, TEM, etc.), demonstrating strong systematicity and providing solid support for the promotion and application of this technology.

[0031] 3. The ultimate value of this invention lies in transforming self-made high-quality powder into high-performance ceramics, using the small-particle-size, low-oxygen ZrB2-SiC multiphase powder and its one-step controllable synthesis method. ZrB2-SiC multiphase ceramics (Ceramic B) prepared from the self-made powder using spark plasma sintering (SPS) technology exhibit a relative density of 99.24%, with Vickers hardness, flexural strength, and fracture toughness reaching 17.93 GPa, 470.00 MPa, and 4.87 MPa·m¹ / ², respectively. All key mechanical properties are significantly superior to the comparative ceramic (Ceramic A) prepared from commercially available powder. This performance leap is directly attributed to the highly dense, uniform, and fine microstructure formed by the high sintering activity of the self-made powder, and the effective toughening mechanism activated by this process, primarily involving crack deflection and branching. This fully demonstrates that the present invention has successfully established a technological chain from "high-quality powder synthesis" to "high-performance ceramic preparation," providing a practical and advantageous overall solution to overcome the bottleneck in the preparation of high-performance ZrB2-SiC ultra-high temperature ceramics, and has broad application potential in the field of thermal protection in extreme environments such as aerospace. Detailed Implementation

[0032] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0033] Example

[0034] Examples of a small-particle-size, low-oxygen ZrB2-SiC multiphase powder, its one-step controllable synthesis method, and its application in high-performance ceramics.

[0035] A small-particle-size, low-oxygen ZrB2-SiC multiphase powder and its one-step controllable synthesis method, comprising the following steps:

[0036] Raw material preparation steps: Provide zirconium source, boron source, silicon source and carbon source, wherein the zirconium source is ZrO2 powder, the boron source is B4C powder, the silicon source is elemental Si powder, and the carbon source is activated carbon powder.

[0037] Preparation steps: Weigh and mix the raw materials in a molar ratio of n(ZrO2):n(B4C):n(Si):n(C) = 3:(1.65~1.95):(0.5~1.0):(4.95~6.05);

[0038] Mixing step: The weighed raw materials are mechanically mixed to obtain a uniformly mixed raw material powder;

[0039] Reaction steps: The mixed raw material powder is placed in a reaction device under an inert atmosphere and subjected to a boron-carbon thermal reduction reaction through a heat treatment process to synthesize ZrB2-SiC multiphase powder; the heat treatment process includes: heating to 1200-1300℃ at a first heating rate, then heating to the final reaction temperature of 1400-1600℃ at a second heating rate lower than the first heating rate, and holding at the final reaction temperature for 30-120 minutes;

[0040] Post-processing steps: After the reaction is complete, the product is cooled to room temperature in the furnace to obtain ZrB2-SiC multiphase powder;

[0041] Among them, the maximum particle size D100 of the ZrB2-SiC composite powder is less than 0.71 μm, and its phase composition, as analyzed by X-ray diffraction, contains only ZrB2 and β-SiC phases.

[0042] Specifically, in the batching step, the preferred molar ratio of the raw materials is n(ZrO2): n(B4C): n(Si): n(C) = 3: 1.8: 1: 5.5.

[0043] Specifically, in the reaction steps, the final reaction temperature is preferably 1500℃, and the holding time is preferably 60 minutes.

[0044] Specifically, the first heating rate is 3-8℃ / min, and the second heating rate is 1-3℃ / min.

[0045] Specifically, in the mixing step, mechanical mixing includes premixing in an agate mortar, followed by dry ball milling in a planetary ball mill at a speed of 150-250 rpm for 6-15 hours.

[0046] Specifically, the inert atmosphere is a high-purity argon atmosphere with a flow rate of 30-50 mL / min and a purity of not less than 99.999%.

[0047] Specifically, by adjusting the molar amount of n(Si) in the ingredients, the molar ratio of ZrB2 to SiC in the prepared ZrB2-SiC multiphase powder can be precisely controlled within the range of 2:1 to 4:1.

[0048] Specifically, the multiphase powder consists of ZrB2 phase and β-SiC phase, with a maximum particle size D100 of less than 0.71 μm, an average particle size of 0.1-0.6 μm, and an oxygen content of less than 1.0 wt%.

[0049] A method for preparing high-performance ZrB2-SiC multiphase ceramics includes the following steps:

[0050] The small-particle-size, low-oxygen ZrB2-SiC multiphase powder as described in claim 8 is provided as a raw material;

[0051] The multiphase powder is subjected to spark plasma sintering. The sintering process is as follows: in a vacuum environment, the temperature is raised to 1650-1750℃ at a heating rate of 80-120℃ / min, while an axial pressure of 25-35 MPa is applied, and the temperature is held at the highest temperature for 3-8 minutes.

[0052] After sintering, the ceramic is cooled in the furnace to obtain a high-performance ZrB2-SiC multiphase ceramic.

[0053] Specifically, the relative density of the multiphase ceramic is not less than 99%, the Vickers hardness is not less than 17.5 GPa, the flexural strength is not less than 450 MPa, and the fracture toughness is not less than 4.8 MPa·m¹ / ². The microstructure of the multiphase ceramic is a uniform fine-grained structure, and its fracture morphology shows that the fracture mode is a mixed mode of transgranular fracture and intergranular fracture. Its toughening mechanism includes crack deflection and crack branching caused by SiC particles.

[0054] Through the above technical solution, this invention presents a small-particle-size, low-oxygen ZrB2-SiC multiphase powder, its one-step controllable synthesis method, and its application in high-performance ceramics. The core of this invention lies in the successful development of a novel one-step synthesis strategy based on boron-carbothermic reduction through systematic optimization of raw material ratios and process parameters. This method uses industrial-grade ZrO2, B4C, elemental Si, and activated carbon as raw materials. Its key innovation lies in precise ratio design: an excess of approximately 20 mol.% B4C is used to compensate for the volatilization of the mesophase B2O3; the carbon source is controlled to the theoretical amount to avoid residue or deficiency; and the precise control of the two-phase ratio in the final powder is achieved by adjusting the Si content. By utilizing the optimal process window of holding at 1500℃ for 1 hour, the defects of traditional methods, such as large particle size and easy inclusion of impurity phases, were successfully overcome. This resulted in the preparation of ZrB2-SiC multiphase powder with small particle size (D100 < 0.71 μm), low oxygen content (no oxygen-containing impurity phases), high purity, and a flexible two-phase ratio adjustable between 2:1 and 4:1. More importantly, microstructural analysis showed that the two-phase interface exhibited semi-coherent bonding and low lattice distortion rate, laying an ideal raw material foundation for the preparation of high-performance ceramics. The advantages of this invention are not only reflected in the final powder performance but also in the maturity and reliability of the process itself. Through detailed experimental research, this invention clarified the key parameters of the entire process, from raw material pretreatment and mixing to staged heating reaction, forming a clear and repeatable operating guide. This method eliminates expensive or complex raw materials and precursors, and all equipment involved is conventional high-temperature furnaces, making the entire process low-cost, simple to operate, and highly promising for industrial application. The entire technical solution forms a complete closed loop, from the powder synthesis mechanism (such as the multi-stage formation process revealed by TG-DSC analysis) to the final product performance characterization (XRD, SEM, TEM, etc.), demonstrating strong systematicity and providing solid support for the promotion and application of this technology. The ultimate value of this invention is manifested by transforming self-made high-quality powder into high-performance ceramics. ZrB2-SiC multiphase ceramics (ceramic B) prepared using self-made powder as raw material and spark plasma sintering (SPS) technology have a relative density as high as 99.24%, and Vickers hardness, flexural strength, and fracture toughness reach 17.93 GPa, 470.00 MPa, and 4.87 MPa·m¹ / ², respectively. All key mechanical properties are significantly better than those of the comparative ceramic (ceramic A) prepared from commercially available powder. The leap in performance is directly attributed to the highly dense, uniform, and fine microstructure formed by the high sintering activity of the self-made powder, and the effective toughening mechanism activated by this, mainly involving crack deflection and branching. This fully demonstrates that the present invention has successfully established a technological chain from "high-quality powder synthesis" to "high-performance ceramic preparation," providing a practical and advantageous overall solution to overcome the bottleneck in the preparation of high-performance ZrB2-SiC ultra-high temperature ceramics, and has broad application potential in the field of thermal protection in extreme environments such as aerospace.

[0055] Example 1: Preparation of ZrB2-SiC multiphase powder under optimal ratio and process

[0056] Raw material ratio: Weigh out nano ZrO2 powder (≤100 nm), B4C powder (~500 nm), Si powder (~75 μm) and activated carbon powder (~48 μm) according to n(ZrO2):n(B4C):n(Si):n(C) = 3 : 1.8 : 1 : 5.5.

[0057] Mixing: Premix the weighed raw materials in an agate mortar for 30 minutes, then place them in a planetary ball mill jar and dry-mill at 200 rpm for 12 hours to ensure the raw materials are fully mixed.

[0058] Reaction sintering: The uniformly mixed powder was loaded into a high-purity graphite crucible and placed in a tube furnace. High-purity argon gas (flow rate 40 mL / min) was introduced into the furnace as a protective atmosphere. A segmented heating program was adopted: first, the temperature was increased to 1300℃ at a rate of 5℃ / min, then increased to 1500℃ at a rate of 2℃ / min, and the reaction was held at 1500℃ for 1 hour.

[0059] Cooling and sampling: After the reaction is completed, cool to room temperature according to the cooling rate program of the heating process, and take out the reaction product to obtain ZrB2-SiC multiphase powder.

[0060] Characterization results:

[0061] Phase analysis (XRD): Only ZrB2 and β-SiC diffraction peaks were detected in the product, and no impurity phases were present, indicating that the reaction was complete.

[0062] Microscopic morphology (SEM): The powder is nearly equiaxed, well dispersed, with an average particle size of about 0.5-0.54 μm and a uniform particle size distribution.

[0063] Microstructure (TEM / HRTEM): The interface between the ZrB2 and SiC phases is clear. HRTEM shows that the lattice matching at the interface is good, which is a semi-coherent interface with low lattice distortion rate.

[0064] Example 2: Adjusting the ratio of two phases with different Si contents

[0065] With a fixed n(ZrO2):n(B4C):n(C) ratio of 3:1.8:5.5, a reaction temperature of 1500℃, and a holding time of 1 hour, powders with different two-phase ratios were prepared by varying the amount of Si added (n(Si) was 0.5, 1.0, and 1.5, corresponding to n(ZrO2):n(Si) ratios of 4:1, 3:1, and 2:1). XRD and Rietveld refinement results showed that the products had high purity, and the molar ratio of ZrB2:SiC could be precisely controlled near the set ratio (4:1, 3:1, 2:1) with a deviation of less than ±2 mol%. SEM showed that as the SiC content increased, the powder particle size tended to decrease, and the morphology became more equiaxed.

[0066] Example 3: Preparation of high-performance ZrB2-SiC multiphase ceramics (Ceramic B)

[0067] Raw materials: Self-made ZrB2-SiC multiphase powder (ZrB2:SiC ≈ 3:1) prepared in Example 1.

[0068] Sintering process: Spark plasma sintering (SPS) is adopted. The powder is loaded into a graphite mold, heated to 1700℃ at a rate of 100℃ / min under vacuum, axial pressure of 30 MPa is applied and held for 5 minutes.

[0069] Ceramic properties: The obtained ceramic B has a relative density of up to 99.24%, and its Vickers hardness, flexural strength, and fracture toughness reach 17.93 GPa, 470.00 MPa, and 4.87 MPa·m¹ / ², respectively. Its fracture surface SEM shows a uniform fine-grained structure.

[0070] Comparative example: Ceramics prepared using commercially available powders (Ceramic A)

[0071] In comparison, commercially available ZrB2 and SiC powders with an average particle size of 1-3 μm were used, mixed in the same volume fraction (ZrB2-25 vol% SiC), and sintered using the same SPS process (1700℃ / 30 MPa / 5 min) to prepare ceramic A. Its relative density was only 97.15%, and its Vickers hardness, flexural strength, and fracture toughness were 15.61 GPa, 322.83 MPa, and 3.96 MPa·m¹ / ², respectively. The fracture morphology showed that it had large grains and numerous pores.

[0072] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A small-particle-size, low-oxygen ZrB2-SiC multiphase powder and its one-step controllable synthesis method, characterized in that: Includes the following steps: Raw material preparation steps: Provide zirconium source, boron source, silicon source and carbon source, wherein the zirconium source is ZrO2 powder, the boron source is B4C powder, the silicon source is elemental Si powder and the carbon source is activated carbon powder; Preparation steps: Weigh and mix the raw materials in a molar ratio of n(ZrO2):n(B4C):n(Si):n(C) = 3:(1.65~1.95):(0.5~1.0):(4.95~6.05); Mixing step: The weighed raw materials are mechanically mixed to obtain a uniformly mixed raw material powder; Reaction steps: The mixed raw material powder is placed in a reaction device under an inert atmosphere and subjected to a boron-carbon thermal reduction reaction through a heat treatment process to synthesize the ZrB2-SiC multiphase powder; the heat treatment process includes: heating to 1200-1300℃ at a first heating rate, then heating to the final reaction temperature of 1400-1600℃ at a second heating rate lower than the first heating rate, and holding at the final reaction temperature for 30-120 minutes; Post-processing steps: After the reaction is complete, the product is cooled to room temperature in the furnace to obtain the ZrB2-SiC multiphase powder; The maximum particle size D100 of the ZrB2-SiC multiphase powder is less than 0.71 μm, and its phase composition, as determined by X-ray diffraction analysis, contains only ZrB2 and β-SiC phases.

2. The small-particle-size, low-oxygen ZrB2-SiC multiphase powder and its one-step controllable synthesis method according to claim 1, characterized in that: In the batching step, the preferred molar ratio of the raw materials is n(ZrO2): n(B4C): n(Si): n(C) = 3: 1.8: 1: 5.

5.

3. The small-particle-size, low-oxygen ZrB2-SiC multiphase powder and its one-step controllable synthesis method according to claim 1, characterized in that: In the reaction step, the final reaction temperature is preferably 1500°C, and the holding time is preferably 60 minutes.

4. The small-particle-size, low-oxygen ZrB2-SiC multiphase powder and its one-step controllable synthesis method according to claim 1, characterized in that: The first heating rate is 3-8℃ / min, and the second heating rate is 1-3℃ / min.

5. The small-particle-size, low-oxygen ZrB2-SiC multiphase powder and its one-step controllable synthesis method according to claim 1, characterized in that: In the mixing step, the mechanical mixing includes premixing in an agate mortar, followed by dry ball milling in a planetary ball mill at a speed of 150-250 rpm for 6-15 hours.

6. The small-particle-size, low-oxygen ZrB2-SiC multiphase powder and its one-step controllable synthesis method according to claim 1, characterized in that: The inert atmosphere is a high-purity argon atmosphere with a flow rate of 30-50 mL / min and a purity of not less than 99.999%.

7. The small-particle-size, low-oxygen ZrB2-SiC multiphase powder and its one-step controllable synthesis method according to claim 1, characterized in that: By adjusting the molar amount of n(Si) in the feed, the molar ratio of ZrB2 to SiC in the prepared ZrB2-SiC multiphase powder can be precisely controlled within the range of 2:1 to 4:

1.

8. The small-particle-size, low-oxygen ZrB2-SiC multiphase powder and its one-step controllable synthesis method according to claim 1, characterized in that: The multiphase powder is composed of ZrB2 phase and β-SiC phase, with a maximum particle size D100 of less than 0.71 μm, an average particle size of 0.1-0.6 μm, and an oxygen content of less than 1.0 wt%.

9. A method for preparing high-performance ZrB2-SiC multiphase ceramics, characterized in that: Includes the following steps: The small-particle-size, low-oxygen ZrB2-SiC multiphase powder as described in claim 8 is provided as a raw material; The composite powder is subjected to spark plasma sintering. The sintering process is as follows: in a vacuum environment, the temperature is raised to 1650-1750℃ at a heating rate of 80-120℃ / min, while an axial pressure of 25-35 MPa is applied, and the temperature is held at the highest temperature for 3-8 minutes. After sintering, the ceramic is cooled in the furnace to obtain the high-performance ZrB2-SiC multiphase ceramic.

10. A small-particle-size, low-oxygen ZrB2-SiC multiphase powder according to claim 9 and its one-step controllable synthesis method: characterized in that: The relative density of the multiphase ceramic is not less than 99%, the Vickers hardness is not less than 17.5 GPa, the flexural strength is not less than 450 MPa, and the fracture toughness is not less than 4.8 MPa·m¹ / ². The microstructure of the multiphase ceramic is a uniform fine-grained structure, and its fracture morphology shows that the fracture mode is a mixed mode of transgranular fracture and intergranular fracture. Its toughening mechanism includes crack deflection and crack branching caused by SiC particles.