SiC-TiB2-TiC composite ceramic as well as preparation method and application thereof

Abstract

The invention relates to the technical field of ceramic materials, in particular to SiC-TiB2-TiC composite ceramic, a preparation method and application thereof, and the preparation method comprises the following steps: respectively weighing raw material powder according to a component design ratio; uniformly mixing and fully drying; and sintering in a vacuum atmosphere by using a discharge plasma sintering furnace at the sintering temperature of 1900-2000 DEG C under the pressure of 40-60 MPa for 10-15 minutes to finally obtain the compact SiC-TiB2-TiC composite ceramic. In order to solve the problem that commercial TiB2 powder is large in particle size and is directly introduced to cause insufficient electrical properties and electrical discharge machining properties of the SiC-TiB2 composite ceramic, TiC is introduced into a SiC-TiB2 system, and in-situ formation and grain pinning effects in a reaction sintering process are utilized, so that a microstructure is refined, and the connectivity of a conductive network is enhanced. Compared with the composite ceramic without TiC, the material prepared by the invention has more excellent conductivity and electrical discharge machining performance, the preparation process is simple, and complicated subsequent treatment is not needed.

Description

Technical Field

[0001] This invention relates to the field of ceramic materials technology, specifically to a SiC-TiB2-TiC multiphase ceramic, its preparation method, and its application. Background Technology

[0002] SiC ceramics possess excellent properties such as high temperature resistance, corrosion resistance, wear resistance, neutron radiation resistance, and oxidation resistance, while also exhibiting high thermal conductivity and a low coefficient of thermal expansion, making them widely used in petrochemical, machinery manufacturing, and aerospace industries. However, SiC ceramics have relatively poor mechanical properties and are difficult to machine quickly and precisely using conventional machining methods, limiting their further applications. TiB2, on the other hand, has a high melting point, high strength, high hardness, and low density, and its coefficient of thermal expansion differs significantly from that of SiC. Adding TiB2 to a SiC matrix can not only maintain the low density and high hardness characteristics of SiC ceramics but also improve their mechanical properties. Furthermore, TiB2 has good electrical conductivity and can be used to prepare multiphase conductive ceramics, thereby supporting electrical discharge machining (EDM), improving processing efficiency, and reducing costs. However, commercial TiB2 powder typically has a large particle size, and its direct introduction into the SiC matrix results in a rough microstructure, limited performance improvement, and unsatisfactory EDM efficiency and surface quality. Compared to TiB2, TiC has lower thermal conductivity and similar electrical conductivity, which is beneficial for the stability and efficiency of the electrical discharge machining process. Furthermore, the difference in thermal expansion coefficients between TiC and SiC can induce toughening mechanisms such as crack deflection, bridging, and branching, further improving the fracture toughness of the material.

[0003] In view of the above-mentioned defects, the inventors of this invention have finally obtained this invention after a long period of research and practice. Summary of the Invention

[0004] The purpose of this invention is to solve the problem that commercial TiB2 powder usually has a large particle size, which leads to a rough microstructure and limited performance improvement when directly introduced into the SiC matrix, and the electrical discharge machining efficiency and surface quality are still not ideal. The invention provides a SiC-TiB2-TiC multiphase ceramic, its preparation method and its application.

[0005] To achieve the above objectives, this invention discloses a method for preparing SiC-TiB2-TiC multiphase ceramics, comprising the following steps:

[0006] S1, mix SiC, B4C, TiC and Si powders evenly and dry them;

[0007] S2, the dried mixed powder from step S1 is loaded into a graphite mold and placed in a discharge plasma sintering furnace for sintering in a vacuum atmosphere.

[0008] In step S1, the mass percentages of SiC, B4C, TiC, and Si powder are as follows: 0.15-0.25 wt% SiC, 0.13-0.15 wt% B4C, 0.38-0.49 wt% TiC, and 0.21-0.23 wt% Si powder.

[0009] In step S1, the particle size of SiC powder is 0.1-5 µm, the particle size of B4C powder is 0.1-5 µm, the particle size of TiC powder is 0.1-3 µm, and the particle size of Si powder is 0.1-1 µm.

[0010] In step S1, the powder mixing method is horizontal ball milling, the ball milling medium is anhydrous ethanol, the grinding ball material is ZrO2, the ball mill speed is 60~100 rpm, and the mixing time is 24~36 hours.

[0011] The grinding balls are divided into three different diameters: large, medium, and small. The mass ratio of the three different diameter grinding balls is 1:(2-2.5):(4-4.5).

[0012] The mass ratio of the grinding ball to the mixed powder is (6-7):1, and the mass ratio of anhydrous ethanol to the mixed powder is (1.2-1.4):1.

[0013] In step S2, sintering is performed using vacuum sintering or sintering in an inert atmosphere.

[0014] In step S2, the sintering temperature is 1900~2000 ℃, the pressure is 40~60 MPa, and the holding time is 10~15 min.

[0015] This invention also discloses the SiC-TiB2-TiC multiphase ceramic prepared by the above preparation method and its application in the fields of petrochemicals, machinery manufacturing, and aerospace.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: By optimizing the specific raw material formulation and raw material particle size, the present invention introduces TiB2 and TiC into the SiC matrix, and utilizes the in-situ reaction and phase composition control during the sintering process to achieve synergistic optimization of microstructure refinement, mechanical properties enhancement and electrical discharge machining performance. Its mechanism of action is as follows: First, an in-situ reaction occurs during sintering to generate fine and uniformly distributed TiB2 grains. This process effectively pins grain boundaries and inhibits abnormal grain growth, significantly improving the hardness and strength of the material through grain refinement. Second, by controlling the TiC content through the raw material ratio, TiC maintains the high electrical conductivity of the multiphase ceramic while significantly reducing the overall thermal conductivity of the material. This synergistic optimization of thermoelectric properties makes the discharge energy more concentrated during EDM, thereby greatly improving the etching efficiency and the surface quality of the processed material. Third, by utilizing the difference in thermal expansion coefficients among SiC, TiB2, and TiC, a beneficial residual stress field is formed after sintering and cooling, which can induce multiple toughening mechanisms such as crack deflection, branching, and bridging of TiC particles, significantly improving the fracture toughness of the material. In addition, the conductive network formed by TiB2 and TiC ensures the stability and efficiency of the discharge process. Attached Figure Description

[0017] Figure 1 The electrical discharge machining surface morphology of the SiC-TiB2-TiC multiphase ceramic in Example 1 of this invention;

[0018] Figure 2 The electrical discharge machining surface morphology of the SiC-TiB2-TiC multiphase ceramic in Example 2 of this invention;

[0019] Figure 3 The electrical discharge machining surface morphology of the SiC-TiB2-TiC multiphase ceramic in Example 3 of this invention;

[0020] Figure 4 The electrical discharge machining surface morphology of the SiC-TiB2-TiC multiphase ceramic in Example 4 of this invention;

[0021] Figure 5 The electrical discharge machining surface morphology of the SiC-TiB2-TiC multiphase ceramic in Example 5 of this invention;

[0022] Figure 6 The electrical discharge machining (EDM) surface morphology of the SiC-TiB2-TiC multiphase ceramic in Example 6 of this invention is shown. Detailed Implementation

[0023] The above-mentioned and other technical features and advantages of the present invention will be described in more detail below with reference to the accompanying drawings.

[0024] Example 1

[0025] 2.66 g of SiC powder with a particle size of 1 µm, 1.56 g of B4C powder with a particle size of 3.12 µm, 4.79 g of TiC powder with a particle size of 0.8 µm, and 2.38 g of Si powder with a particle size of 0.5 µm were weighed separately. The weighed powders were mixed evenly and thoroughly dried. The dried powder was placed into a graphite mold and sintered in a vacuum atmosphere in a discharge plasma sintering furnace at a temperature of 1950 ℃, a pressure of 50 MPa, and a holding time of 12 min. After natural cooling, a SiC-30 vol% TiB2-5 vol% TiC conductive multiphase ceramic was obtained. The prepared SiC-TiB2-TiC multiphase ceramic was tested to have a Vickers hardness of 26.84 GPa, a flexural strength of 542 MPa, and a fracture toughness of 4.64 MPa·m. 1 / 2 The conductivity is 4.81 × 10⁻⁶. 4 S / m, thermal conductivity 53.19 W / (m·K), material removal rate 6.84 mm 3 / min, with a roughness of 3.84 μm. For example... Figure 1 As shown, after wire cutting, the surface height of the multiphase ceramic material ranges from -19.859 μm to 19.228 μm within a scanning area of ​​approximately 530 μm × 707 μm, with a total peak-to-valley difference of approximately 39.09 μm. The material surface exhibits an overall irregular and dense texture, with obvious protrusions and depressions visible in some areas, reflecting the high surface roughness of the processed material.

[0026] In comparison, SiC-30 vol%TiB2 multiphase ceramics were prepared using 1 µm SiC powder, 3.12 µm B4C powder, 0.8 µm TiC powder, and 0.5 µm Si powder as raw materials, and employing the same mixing and sintering methods. These ceramics exhibited a Vickers hardness of 25.51 GPa, a flexural strength of 489 MPa, and a fracture toughness of 4.13 MPa·m. 1 / 2 The conductivity is 2.21 × 10⁻⁶. 4 S / m, thermal conductivity 57.45 W / (m·K), material removal rate 5.62 mm 3 The surface roughness is 4.51 μm. This demonstrates that, using the same raw material powder, adjusting the TiC content can improve the mechanical and processing properties of multiphase ceramics.

[0027] Example 2

[0028] 2.19 g of SiC powder with a particle size of 1 µm, 1.56 g of B4C powder with a particle size of 3.12 µm, 4.09 g of TiC powder with a particle size of 0.8 µm, and 2.38 g of Si powder with a particle size of 0.5 µm were weighed out. The weighed powders were mixed evenly and thoroughly dried. The dried powder was placed into a graphite mold and sintered in a vacuum atmosphere in a discharge plasma sintering furnace at 1950 ℃, 50 MPa, and a holding time of 12 min. After natural cooling, a SiC-30 vol% TiB2-10 vol% TiC conductive multiphase ceramic was obtained. The prepared SiC-TiB2-TiC multiphase ceramic was tested and found to have a Vickers hardness of 28.55 GPa, a flexural strength of 613 MPa, and a fracture toughness of 5.47 MPa·m. 1 / 2 The conductivity is 7.56 × 10⁻⁶. 4 S / m, thermal conductivity 50.66 W / (m·K), material removal rate 7.85 mm 3 / min, with a roughness of 3.12 μm. For example... Figure 2 As shown, after wire cutting, the surface height of the multiphase ceramic material ranges from -15.093 μm to 16.761 μm within a scanning area of ​​approximately 530 μm × 707 μm, with a total peak-to-valley difference of approximately 31.85 μm. Obvious protrusions and depressions are visible on the material surface, consistent with... Figure 1 In comparison, the peak-valley height difference has decreased slightly, but the surface morphology is still relatively rough.

[0029] In comparison, SiC-30 vol%TiB2 multiphase ceramics were prepared using 1 µm SiC powder, 3.12 µm B4C powder, 0.8 µm TiC powder, and 0.5 µm Si powder as raw materials, and employing the same mixing and sintering methods. These ceramics exhibited a Vickers hardness of 25.51 GPa, a flexural strength of 489 MPa, and a fracture toughness of 4.13 MPa·m. 1 / 2 The conductivity is 2.21 × 10⁻⁶. 4 S / m, thermal conductivity 57.45 W / (m·K), material removal rate 5.62 mm 3 The surface roughness is 4.51 μm. This demonstrates that, using the same raw material powder, adjusting the TiC content can improve the mechanical and processing properties of multiphase ceramics.

[0030] Example 3

[0031] 1.72 g of SiC powder with a particle size of 1 µm, 1.56 g of B4C powder with a particle size of 3.12 µm, 5.51 g of TiC powder with a particle size of 0.8 µm, and 2.38 g of Si powder with a particle size of 0.5 µm were weighed separately. The weighed powders were mixed evenly and thoroughly dried. The dried powder was placed into a graphite mold and sintered in a vacuum atmosphere in a discharge plasma sintering furnace at a temperature of 1950 ℃, a pressure of 50 MPa, and a holding time of 12 min. After natural cooling, a SiC-30 vol% TiB2-15 vol% TiC conductive multiphase ceramic was obtained. The prepared SiC-TiB2-TiC multiphase ceramic was tested to have a Vickers hardness of 29.13 GPa, a flexural strength of 657 MPa, and a fracture toughness of 6.23 MPa·m. 1 / 2 The conductivity is 12.48 × 10⁻⁶. 4 S / m, thermal conductivity 47.81 W / (m·K), material removal rate 8.37 mm 3 / min, with a roughness of 2.56 μm. For example... Figure 3 As shown, after wire cutting, the surface height of the multiphase ceramic material ranges from -10.203 μm to 14.006 μm within a scanning area of ​​approximately 530 μm × 707 μm, with a total peak-to-valley difference of approximately 24.21 μm. Obvious protrusions and depressions are also visible on the material surface, but... Figure 2 In comparison, the peak-valley height difference is further reduced, and the surface roughness is significantly reduced.

[0032] In comparison, SiC-30 vol%TiB2 multiphase ceramics were prepared using 1 µm SiC powder, 3.12 µm B4C powder, 0.8 µm TiC powder, and 0.5 µm Si powder as raw materials, and employing the same mixing and sintering methods. These ceramics exhibited a Vickers hardness of 25.51 GPa, a flexural strength of 489 MPa, and a fracture toughness of 4.13 MPa·m. 1 / 2 The conductivity is 2.21 × 10⁻⁶. 4 S / m, thermal conductivity 57.45 W / (m·K), material removal rate 5.62 mm 3 The surface roughness is 4.51 μm. This demonstrates that, using the same raw material powder, adjusting the TiC content can improve the mechanical and processing properties of multiphase ceramics.

[0033] Example 4

[0034] 1.72 g of SiC powder with a particle size of 0.5 µm, 1.56 g of B4C powder with a particle size of 0.5 µm, 5.51 g of TiC powder with a particle size of 0.8 µm, and 2.38 g of Si powder with a particle size of 1 µm were weighed separately. The weighed powders were mixed evenly and thoroughly dried. The dried powder was placed into a graphite mold and sintered in a vacuum atmosphere in a discharge plasma sintering furnace at a temperature of 1950 ℃, a pressure of 50 MPa, and a holding time of 12 min. After natural cooling, a SiC-30 vol% TiB2-15 vol% TiC conductive multiphase ceramic was obtained. The prepared SiC-TiB2-TiC multiphase ceramic was tested and found to have a Vickers hardness of 28.43 GPa, a flexural strength of 572 MPa, and a fracture toughness of 5.44 MPa·m. 1 / 2 The conductivity is 8.61 × 10⁻⁶. 4 S / m, thermal conductivity 50.34 W / (m·K), material removal rate 7.82 mm 3 / min, with a roughness of 3.15 μm. For example... Figure 4 As shown, after wire cutting, the surface height of the multiphase ceramic material ranges from -17.134 μm to 22.537 μm within a scanning area of ​​approximately 530 μm × 707 μm, with a total peak-to-valley difference of approximately 39.67 μm. The material surface exhibits more pronounced peak-to-valley undulations and localized large protrusions, further enhancing the surface roughness. This reflects a more intense etching process under these processing conditions, resulting in a more irregular microstructure.

[0035] In comparison, SiC-30 vol%TiB2 multiphase ceramics were prepared using 1 µm SiC powder, 3.12 µm B4C powder, 0.8 µm TiC powder, and 0.5 µm Si powder as raw materials, and employing the same mixing and sintering methods. These ceramics exhibited a Vickers hardness of 25.51 GPa, a flexural strength of 489 MPa, and a fracture toughness of 4.13 MPa·m. 1 / 2 The conductivity is 2.21 × 10⁻⁶. 4 S / m, thermal conductivity 57.45 W / (m·K), material removal rate 5.62 mm 3 The surface roughness is 4.51 μm. This demonstrates that, using the same raw material powder, adjusting the TiC content and particle size can improve the mechanical and processing properties of multiphase ceramics.

[0036] Example 5

[0037] 1.72 g of SiC powder with a particle size of 3 µm, 1.56 g of B4C powder with a particle size of 5.0 µm, 5.51 g of TiC powder with a particle size of 3.0 µm, and 2.38 g of Si powder with a particle size of 1 µm were weighed separately. The weighed powders were mixed evenly and thoroughly dried. The dried powder was placed into a graphite mold and sintered in a vacuum atmosphere in a discharge plasma sintering furnace at a temperature of 1950 ℃, a pressure of 50 MPa, and a holding time of 12 min. After natural cooling, SiC-30 vol% TiB2-15 vol% TiC conductive multiphase ceramic was obtained. The prepared SiC-TiB2-TiC multiphase ceramic was tested to have a Vickers hardness of 28.84 GPa, a flexural strength of 561 MPa, and a fracture toughness of 5.73 MPa·m. 1 / 2 The conductivity is 7.49 × 10⁻⁶. 4 S / m, thermal conductivity 49.22 W / (m·K), material removal rate 7.73 mm 3 / min, with a roughness of 3.46 μm. For example... Figure 5 As shown, after wire cutting, the surface height of the multiphase ceramic material ranged from -17.449 μm to 43.704 μm within a scanning area of ​​approximately 530 μm × 707 μm, with a total peak-to-valley difference of approximately 61.15 μm. This relatively large value is due to some protrusions. Multiple isolated high protrusions and deep valleys appeared on the material surface, with particularly significant abrupt changes in height in local areas. The surface roughness and irregularity were significantly increased, reflecting a more severe local erosion phenomenon under these processing conditions, resulting in a highly non-uniform microstructure.

[0038] In comparison, SiC-30 vol%TiB2 multiphase ceramics were prepared using 1 µm SiC powder, 3.12 µm B4C powder, 0.8 µm TiC powder, and 0.5 µm Si powder as raw materials, and employing the same mixing and sintering methods. These ceramics exhibited a Vickers hardness of 25.51 GPa, a flexural strength of 489 MPa, and a fracture toughness of 4.13 MPa·m. 1 / 2 The conductivity is 2.21 × 10⁻⁶. 4 S / m, thermal conductivity 57.45 W / (m·K), material removal rate 5.62 mm 3 The surface roughness is 4.51 μm. This demonstrates that, using the same raw material powder, adjusting the TiC content and particle size can improve the mechanical and processing properties of multiphase ceramics.

[0039] Example 6

[0040] 1.72 g of SiC powder with a particle size of 3 µm, 1.56 g of B4C powder with a particle size of 5.0 µm, 5.51 g of TiC powder with a particle size of 0.5 µm, and 2.38 g of Si powder with a particle size of 0.5 µm were weighed separately. The weighed powders were mixed evenly and thoroughly dried. The dried powder was placed into a graphite mold and sintered in a vacuum atmosphere in a discharge plasma sintering furnace at 1950 ℃, 50 MPa, and a holding time of 12 min. After natural cooling, a SiC-30 vol% TiB2-15 vol% TiC conductive multiphase ceramic was obtained. The prepared SiC-TiB2-TiC multiphase ceramic was tested and found to have a Vickers hardness of 27.69 GPa, a flexural strength of 554 MPa, and a fracture toughness of 5.61 MPa·m. 1 / 2 The conductivity is 9.81 × 10⁻⁶. 4 S / m, thermal conductivity 49.62 W / (m·K), material removal rate 8.07 mm 3 The surface roughness was 2.95 μm. After wire cutting, the surface height of the multiphase ceramic material ranged from -12.171 μm to 15.921 μm within a scanning area of ​​approximately 530 μm × 707 μm, with a total peak-to-valley difference of approximately 28.09 μm. The surface texture exhibited a finer, more uniform distribution of bumps and depressions, with a few isolated micro-protrusions and shallow pits visible in some areas. This indicates that the etching process was more uniform under these processing conditions, resulting in improved surface morphology uniformity.

[0041] In comparison, SiC-30 vol%TiB2 multiphase ceramics were prepared using 1 µm SiC powder, 3.12 µm B4C powder, 0.8 µm TiC powder, and 0.5 µm Si powder as raw materials, and employing the same mixing and sintering methods. These ceramics exhibited a Vickers hardness of 25.51 GPa, a flexural strength of 489 MPa, and a fracture toughness of 4.13 MPa·m. 1 / 2 The conductivity is 2.21 × 10⁻⁶. 4 S / m, thermal conductivity 57.45 W / (m·K), material removal rate 5.62 mm 3 The surface roughness is 4.51 μm. This demonstrates that, using the same raw material powder, adjusting the TiC content and particle size can improve the mechanical and processing properties of multiphase ceramics.

[0042] The above description is merely a preferred embodiment of the present invention and is illustrative rather than restrictive. Those skilled in the art will understand that many changes, modifications, and even equivalents can be made within the spirit and scope defined by the claims of the present invention, all of which will fall within the protection scope of the present invention.

Claims

1. A method for preparing SiC-TiB2-TiC multiphase ceramics, characterized in that, Includes the following steps: S1, mix SiC, B4C, TiC and Si powders evenly and dry them; S2, the dried mixed powder from step S1 is loaded into a graphite mold and placed in a discharge plasma sintering furnace for sintering in a vacuum atmosphere.

2. The method for preparing SiC-TiB2-TiC multiphase ceramics as described in claim 1, characterized in that, In step S1, the mass percentages of SiC, B4C, TiC, and Si powder are as follows: 0.15-0.25 wt% SiC, 0.13-0.15 wt% B4C, 0.38-0.49 wt% TiC, and 0.21-0.23 wt% Si powder.

3. The method for preparing SiC-TiB2-TiC multiphase ceramics as described in claim 1, characterized in that, In step S1, the particle size of SiC powder is 0.1-5 µm, the particle size of B4C powder is 0.1-5 µm, the particle size of TiC powder is 0.1-3 µm, and the particle size of Si powder is 0.1-1 µm.

4. The method for preparing SiC-TiB2-TiC multiphase ceramics as described in claim 1, characterized in that, In step S1, the powder mixing method is horizontal ball milling, the ball milling medium is anhydrous ethanol, the grinding ball material is ZrO2, the ball mill speed is 60~100 rpm, and the mixing time is 24~36 hours.

5. The method for preparing SiC-TiB2-TiC multiphase ceramics as described in claim 3, characterized in that, The grinding balls are divided into three different diameters: large, medium, and small. The mass ratio of the three different diameter grinding balls is 1:(2-2.5):(4-4.5).

6. The method for preparing SiC-TiB2-TiC multiphase ceramics as described in claim 3, characterized in that, The mass ratio of the grinding ball to the mixed powder is (6-7):1, and the mass ratio of anhydrous ethanol to the mixed powder is (1.2-1.4):

1.

7. The method for preparing SiC-TiB2-TiC multiphase ceramics as described in claim 1, characterized in that, In step S2, sintering is performed using vacuum sintering or sintering in an inert atmosphere.

8. The method for preparing SiC-TiB2-TiC multiphase ceramics as described in claim 1, characterized in that, In step S2, the sintering temperature is 1900~2000 ℃, the pressure is 40~60 MPa, and the holding time is 10~15 min.

9. A SiC-TiB2-TiC multiphase ceramic prepared by the preparation method according to any one of claims 1 to 8.

10. The application of the SiC-TiB2-TiC multiphase ceramic as described in claim 9 in the fields of petrochemicals, machinery manufacturing, and aerospace.

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