A honeycomb ceramic and method of making the same

Abstract

The application discloses honeycomb ceramic and a preparation method thereof. A composite additive is added into mixed ceramic raw materials, and the weight ratio of the mixed ceramic raw materials to the composite additive is (30-50):(50-70). The composite additive comprises 30-54 parts of flaky alumina, 2-10 parts of nano-zinc oxide and 1-5 parts of metal molybdenum particles. The honeycomb ceramic is prepared through ball milling, kneading, refining, extrusion forming, drying and sintering. The application replaces bauxite with flaky alumina, adds beneficial additives, i.e. nano-zinc oxide and metal molybdenum particles, and uses the original extrusion forming equipment to realize the layered structure of the flaky alumina, thereby building a shell-like pearl layer structure with the layered alumina as a "brick", the metal molybdenum particles as "mud" and the zinc-aluminum spinel particles as "protrusions".

Description

TECHNICAL FIELD

[0001] The present application relates to the field of ceramics, in particular to a honeycomb ceramic and a preparation method thereof. BACKGROUND

[0002] With the development of industrial technology, the demand for high-performance materials in the fields of aerospace, electronics, national defense, etc. is increasing. Ceramic materials, due to their excellent high-temperature resistance, corrosion resistance and mechanical properties, have become one of the key functional materials. However, traditional ceramic materials are usually limited in their wide application in structural materials due to their high brittleness. Therefore, how to improve the toughness of ceramic materials has become an important research direction in the field of materials science.

[0003] Biological materials in nature, such as the nacreous layer structure of shells, are known for their high toughness and high strength. This nacreous layer is composed of inorganic minerals and organic matter arranged in a nanoscale and microscale order, forming a "brick-mud" structure. This biomimetic structure significantly improves the crack resistance and toughness of the material by embedding rigid particles in a tough matrix and achieving gradient design at the microscale, while retaining excellent strength characteristics.

[0004] Currently, the main methods for preparing ceramics with a nacreous layer structure include freeze casting, gel casting, laminated sintering, 3D printing technology, magnetic or electric field induction, biomimetic template method, and self-assembly method. Different methods have different principles, but all aim to achieve a layered structure of ceramics to approach the nacreous layer structure of shells. Chinese Patent No. CN113004050B discloses a double-toughened composite ceramic material with a shell-like structure and a preparation method thereof. After freezing, hot-pressing sintering of flaky alumina, nano-alumina particles and nano-zirconia particles, the ceramic material is obtained. The principle of freeze casting is to control the directional growth of ice crystals to repel ceramic particles to the channels between the ice crystals. When the channels are narrow enough, the flaky alumina will be oriented in the gaps, and subsequent sublimation of the ice crystals will leave a layered ceramic framework with directional pores. The directional growth of ice crystals is mainly controlled by temperature, and the growth direction of ice crystals is always along the heat flow direction. A large temperature difference is conducive to the directional growth of ice crystals. Therefore, freeze-drying method often uses liquid nitrogen as the freezing material, and in order to obtain dense ceramics, hot-pressing sintering is also needed to remove the pores left after sublimation of ice crystals, resulting in extremely high production cost and making it impossible to be applied on a large scale.

[0005] Patent application DE2450071A1 provides a crystal orientation technology of cordierite honeycomb ceramics, using raw materials with specified structure such as flaky kaolin, layered talc or nano-alumina combined with honeycomb ceramic extrusion molding technology, through the shearing force between ceramic particles in the extrusion process, the flaky kaolin or layered talc is oriented in the plane parallel to the mold wall surface, and the cordierite generated by reaction after sintering is the oriented structure with the c-axis parallel to the axial direction of the honeycomb ceramic, and the c-axis direction of the cordierite crystal has a negative thermal expansion coefficient, so that the axial thermal expansion coefficient of the prepared honeycomb ceramic is extremely low. SUMMARY

[0006] The present application aims to provide a kind of honeycomb ceramics with high compressive strength and high fracture toughness, and a preparation method thereof.

[0007] In order to achieve the above-mentioned purpose, the technical scheme adopted by the present application is as follows:

[0008] A preparation method of honeycomb ceramics, a composite additive is added to the mixed ceramic raw material, the weight ratio of the mixed ceramic raw material and the composite additive is (30-50) :(50-70), the composite additive includes 30-54 parts of flaky alumina, 2-10 parts of nano-zinc oxide and 1-5 parts of metal molybdenum particles, and is prepared by ball milling, kneading, refining, extrusion molding, drying and sintering; preferably, the composite additive includes 45-54 parts of flaky alumina, 4-10 parts of nano-zinc oxide and 1-5 parts of metal molybdenum particles; further preferably, the composite additive includes 48-54 parts of flaky alumina, 4-8 parts of nano-zinc oxide and 2-4 parts of metal molybdenum particles.

[0009] A "brick mud" structure imitating nacreous layer, flaky alumina as brick and metal molybdenum particles as mud;

[0010] A convex structure imitating nacreous layer, nano-zinc oxide as additive, reacting with alumina to form zinc aluminate spinel to form convex structure on flaky alumina;

[0011] A layered structure imitating nacreous layer, flaky alumina in the ceramic is parallel to the extrusion direction through the shearing force of the raw material in the extrusion molding.

[0012] The present application makes the flaky alumina form a layered structure parallel to the extrusion direction by extrusion molding, and the added nano zinc oxide can react with the alumina to generate zinc aluminate spinel microparticles on the flaky alumina, so as to realize the convex structure of the imitation nacre layer. The flaky alumina with the parallel orientation and the surface carrying the zinc aluminate spinel microparticles serves as the brick, and the trace of metal molybdenum particles serves as the mud, so as to realize the "brick-mud" structure of the imitation nacre layer. The honeycomb ceramic prepared by the above method has the characteristics of high compressive strength and high toughness. The increase of the compressive strength is because the alumina layered structure parallel to the extrusion direction can evenly bear the external force. At the same time, the rigid flaky alumina is combined with a small amount of metal molybdenum particles with certain plasticity, and when the crack expands, the pull-out mechanism of the flaky alumina and the plastic deformation of the metal particles effectively consume the energy, and the zinc aluminate spinel convex structure on the flaky alumina can play an interlocking role, so as to avoid excessive slip of the flaky alumina, thereby ensuring the high strength of the ceramic while realizing the high toughness.

[0013] The flaky alumina is the key to high strength and high toughness. The metal molybdenum particles have certain high-temperature oxidation resistance, so the metal molybdenum particles are the optimal choice as the "mud" structure.

[0014] The "brick-mud-interlayer convex" structure of the flaky alumina + nano zinc oxide + metal particles in the above range of the present application effectively improves the strength and toughness of the ceramic. Too much nano zinc oxide will lead to an increase in the number of crystal boundaries existing in the ceramic, a decrease in the binding force between the crystals, and a possible destruction of the flaky structure of the alumina, resulting in a decrease in the mechanical properties. With the increase of the metal molybdenum particles, the interlayer phase of the ceramic increases, which can provide a certain "plastic deformation" space for the ceramic, but generally the toughness and the strength are contradictory, and too much metal particles will reduce the compressive strength of the ceramic.

[0015] In one preferred embodiment, the thickness of the flaky alumina is 0.2-0.4 μm, the equivalent diameter is 3-5 μm, the particle size of the nano zinc oxide is 20-40 nm, and the particle size of the metal molybdenum particles is 5-10 μm.

[0016] The flaky alumina serves as the "brick" structure of the imitation nacre layer, the zinc aluminate spinel microparticles generated by the reaction of the nano zinc oxide serve as the convex structure, and the metal molybdenum particles serve as the "mud" structure of the imitation nacre layer.

[0017] According to the embodiments of the present application, the present application can be further optimized, and the following is the technical scheme formed after optimization:

[0018] The mixed ceramic raw material is a cordierite-mullite composite honeycomb ceramic raw material; preferably, the mixed ceramic raw material comprises the following raw materials in parts by weight: cordierite 2-7 parts, kaolin 1-4 parts, flint clay 0.5-1.5 parts, mullite 20-35 parts, potassium feldspar 2-5 parts, raw talc 3-9 parts, dispersant 0.2-0.5 parts, grinding aid 0.2-0.5 parts.

[0019] Because the flaky alumina is easy to agglomerate, the unevenly dispersed flaky alumina can cause uneven distribution of the extrusion mud, different stress in the mold, and thus difficulty in extrusion, and the addition of the dispersant can ensure the same stress in the mold and realize normal extrusion.

[0020] The kaolin is preferably Suzhou kaolin.

[0021] In one preferred embodiment, the dispersant is sodium dodecyl sulfate.

[0022] In one preferred embodiment, the grinding aid is glycerol.

[0023] In one preferred embodiment, the method for preparing the high-density low-expansion composite honeycomb ceramic comprises the following specific steps

[0024] S1. The raw materials are weighed in parts by weight and ball milled to obtain a mixed material;

[0025] S2. Cellulose, lubricant, plasticizer and water are added to the mixed material, and kneading is performed to obtain a kneaded mud section;

[0026] S3. The kneaded mud section is refined to obtain a refined mud section;

[0027] S4. The refined mud section is placed into a mold for extrusion to obtain a wet green body;

[0028] S5. The wet green body is dried to obtain a dry green body;

[0029] S6. The dry green body is cut at both ends to obtain a cut dry green body;

[0030] S7. The cut dry green body is fired to obtain a ceramic finished product.

[0031] In one preferred embodiment, the length of the mold in S4 is 16-40 mm, preferably 22-26 mm.

[0032] The length of the mold has a certain influence on the orientation of the flaky alumina. If the mold is too long, the forming pressure will be too large, and if the mold is too short, the flaky alumina will be subjected to shear force for a short time, and the orientation effect will not be significant.

[0033] In one preferred embodiment, in S1, the raw materials other than the flake alumina are ball-milled for 2 to 4 hours, and then the flake alumina is added and ball-milled for another 2 to 4 hours at a speed of 200 to 400 revolutions per minute, and a mixture is obtained after ball milling.

[0034] If the ball milling time for flake alumina is too short, the mixing will be insufficient; if the time is too long, the flake structure will be destroyed.

[0035] In one preferred embodiment, the sintering process is as follows: under a nitrogen atmosphere, the temperature is raised to 850-950°C at a rate of 5-10°C / min, then raised to 1200-1300°C at a rate of 2-4°C / min, and held for 2-3 hours; then the temperature is lowered to 800°C and the nitrogen supply is stopped, and the temperature is cooled to room temperature.

[0036] In one preferred embodiment, the kneading agent comprises 1 to 4 parts cellulose, 1 to 3 parts lubricant, and 0.3 to 1 part plasticizer; the lubricant is preferably palm oil, and the plasticizer is preferably polyethylene oxide.

[0037] In one preferred embodiment, the viscosity of the cellulose is 80,000 to 120,000; the melting point of the palm oil is 24 to 28°; and the molecular weight of the polyethylene oxide is 1,000,000 to 8,000,000.

[0038] In S2, the kneading speed is set to 10-50 revolutions per minute, and the kneading time is 10-30 minutes.

[0039] The vacuum degree of refining in S3 is 0.05 to 0.09.

[0040] The present invention also discloses a honeycomb ceramic prepared according to the preparation method described above.

[0041] The present invention also discloses a honeycomb ceramic, wherein the compressive strength of the honeycomb ceramic is 130–195 MPa and the fracture toughness is 6–9 MPa·m. 1 / 2 Preferably, the compressive strength of the honeycomb ceramic is 160–195 MPa, and the fracture toughness is 8–9 MPa·m. 1 / 2 .

[0042] Kneading, refining, molding, and drying are all common steps and methods for preparing honeycomb ceramic heat storage bodies.

[0043] The beneficial effects of this invention are as follows:

[0044] The application develops a high-strength and high-toughness honeycomb ceramic regenerator, without changing the process flow of the honeycomb ceramic, the application replaces bauxite with flaky alumina by optimizing the raw material formula, adds beneficial additives, namely, nano-zinc oxide and metal molybdenum particles, and realizes the layered structure of the flaky alumina by using the original extrusion molding equipment, so as to build a shell-like nacreous layer structure taking the layered alumina as a "brick", the metal molybdenum particles as "mud" and the zinc aluminate particles as "protrusions". Compared with the preparation method of the conventional nacreous layer material, the process flow of the application is simple and does not need to purchase new equipment, so that the production cost is greatly reduced. BRIEF DESCRIPTION OF DRAWINGS

[0045] Figure 1 The standard PDF card of the ceramic phase composition of 10% nano-zinc oxide and zinc aluminate.

[0046] Figure 2 The schematic diagram of the molding mold, wherein figure a is the front view of the mold, figure b is the left view of the mold, figure c is the sectional view of the mold, and 1 is the prism area of the mold. DETAILED DESCRIPTION

[0047] The application is not limited to the following specific embodiments, and the person skilled in the art can implement the application by using other various specific embodiments according to the disclosed content of the application, or any simple change or modification of the design structure and ideas of the application also falls within the protection scope of the application. It should be noted that the embodiments in the application and the features in the embodiments can be combined with each other without conflict. If not specifically stated, the relevant percentages refer to the mass percentages.

[0048] Embodiment 1

[0049] A high-strength and high-toughness shell-like nacreous honeycomb ceramic regenerator.

[0050] The high-strength and high-toughness honeycomb ceramic regenerator comprises basic raw material powder and other components, and the basic raw material powder is composed of the following basic raw materials in parts by weight (kg): 60 parts of flaky alumina + nano-zinc oxide + metal molybdenum particles, 5 parts of cordierite powder, 2 parts of Suzhou kaolin, 0.5 parts of calcined bauxite powder, 25 parts of mullite powder, 3.5 parts of potassium feldspar and 4 parts of raw talc. Then, 5 ‰ of a dispersing agent (sodium dodecyl sulfate) of the total mass of the basic raw material powder and 2 ‰ of a grinding aid (glycerol) of the total mass of the basic raw material powder are added, the ratio of the flaky alumina, the nano-zinc oxide and the metal molybdenum particles is changed, and the performance of the sample is detected.

[0051] The flaky alumina has a thickness of 0.3 μm and an equivalent diameter of 3-5 μm, and serves as a "brick" structure of the shell-like nacreous layer;

[0052] The nano zinc oxide particle size is 30±10nm, and the zinc aluminum spinel particles generated in the reaction serve as "protruding" structures;

[0053] The metal molybdenum particle size is 5-10μm, serving as a "mud" structure of the imitation nacreous pearl layer;

[0054] The preparation method of the honeycomb ceramic heat accumulator is as follows:

[0055] The raw materials except the flaky alumina are put into a ball mill, and ball-milled at a speed of 30 revolutions per minute for 3 hours, and then the flaky alumina is added and ball-milled for 3 hours to obtain a mixture; the mixture is added into a kneader, 10 million viscosity cellulose of 2‰ of the mass of the mixture, 28-degree palm oil of 2‰, 8‰ of 500 million molecular weight polyethylene oxide, and 13% of deionized water are added, the speed of the kneader is set to 30 revolutions per minute, and the kneader is kneaded for 20 minutes to obtain a kneaded mud section; the kneaded mud section is put into a vacuum mud refining machine, and refined at a vacuum degree of 0.07 to obtain a refined mud section; the refined mud section is put into a mold for extrusion molding to obtain a wet blank, and the length of the prismatic area of the mold is 24mm; the wet blank is dried to obtain a dry blank; the dry blank is cut at both ends, and the cutting size is 1.20 times the length of the finished product, to obtain a cut dry blank; the cut dry blank is put into a kiln, and heated to 900℃ at a speed of 5℃ / min under the protection of nitrogen, and then heated to 1250℃ at a speed of 3℃ / min, and kept for two hours; then, the temperature is lowered, the nitrogen is stopped when the temperature is lowered to 800℃, and the temperature is cooled to room temperature.

[0056] The room temperature compressive strength and fracture toughness of the sample are measured, and the specific test method is as follows:

[0057] The compressive strength calculation method is as follows:

[0058] Wherein, σ is the compressive strength (unit: Pa, commonly used MPa); F is the maximum compression force borne by the sample (unit: N); A is the compression area of the sample (unit: m 2 ).

[0059] The ceramic fracture toughness (K IC ) is tested by SENB test, and the calculation formula is as follows: Wherein, F MAX is the maximum load when the sample is broken (unit: N); B is the thickness of the sample (unit: m); W is the width of the sample (unit: m); a is the crack length (unit: m); is a geometric correction factor, which is related to the geometric shape and crack ratio of the sample.

[0060] The test results are shown in Table 1.

[0061] Table 1 Influence of different proportions of flaky alumina, nano zinc oxide and metal molybdenum particles on ceramic performance in Example 1

[0062]

[0063] As shown in the table, in sample 4, when the flaky alumina is 51 parts, the nano zinc oxide is 6 parts, and the metal molybdenum particles are 3 parts, the compressive strength and fracture toughness of the ceramic are the highest, reaching 192.579 MPa and 8.7 MPa·m 1 / 2 , respectively. The "brick" structure of the layered alumina can consume crack propagation energy when encountering cracks, and the zinc aluminate spinel particles generated by the reaction of nano zinc oxide and flaky alumina are embedded on the flaky alumina to form a "protruding" structure, which can limit the excessive slip of flaky alumina and play an interlocking role, ensuring the strength of the imitation shell pearl layer structure. At the same time, the generated zinc aluminate spinel particles can refine the ceramic grains to some extent, which is one of the reasons for the improvement of the strength of the ceramic. However, too much nano zinc oxide will increase the number of crystal boundaries in the ceramic, weaken the bonding force between the crystals, and may also damage the flaky structure of alumina, leading to a decrease in mechanical properties. With the increase of metal molybdenum particles, the interlayer phase of the ceramic increases, which can provide a certain "plastic deformation" space for the ceramic, but in general, toughness and strength are mutually contradictory, and too many metal particles will reduce the compressive strength of the ceramic. Through the above research, the "brick-mud-interlayer protrusion" structure composed of flaky alumina + nano zinc oxide + metal particles effectively improves the strength and toughness of the ceramic.

[0064] Example 2

[0065] Influence of mold length on ceramic performance.

[0066] The difference between this case and Example 1 is that the flaky alumina is fixed at 51 parts, the nano zinc oxide is 6 parts, and the metal molybdenum particles are 3 parts, and the length of the prismatic area of the forming mold is changed. The performance of the ceramic is detected, and the detection results are shown in Table 2:

[0067] Table 2 Influence of different mold lengths on ceramic performance

[0068]

[0069] According to the requirements of the oriented layered alumina structure by extrusion molding, the length of the prism region of the mold needs to meet certain conditions. If the prism region is too short, the alumina sheet structure is not enough time under the action of shear force, leading to incomplete layered orientation, thereby affecting the performance of the final structure. However, the length of the prism region is closely related to the extrusion pressure, and too long mold may lead to the need for higher forming pressure, which may have a series of negative effects, including increased equipment load and rising energy consumption. Therefore, when designing the mold, the length of the mold and the forming pressure must be balanced to ensure the integrity of the layered orientation of the alumina and the production efficiency. As can be seen from the data in the table, the mold with a prism region length of 24 mm is the best choice, at which the honeycomb ceramic prepared has higher compressive strength and fracture toughness and relatively low extrusion pressure.

[0070] Comparative Example 1

[0071] The difference between Comparative Example 1 and Example 1 is that the alumina used in Comparative Example 1 is irregularly shaped.

[0072] Table 3 Effect of different proportions of alumina, nano-zinc oxide and metal molybdenum particles on the performance of ceramics in Comparative Example 1

[0073]

[0074] The flaky alumina is the key to high strength and high toughness. When irregularly shaped alumina raw materials are used, the compressive strength of the ceramic is far inferior to that in Example 1, and the toughness of the ceramic is only derived from the particle toughening of zinc aluminate spinel and the plastic toughening of metal molybdenum particles, which has little toughening effect.

[0075] Comparative Example 2

[0076] The difference between Comparative Example 2 and Example 1 is that the metal particles used in Comparative Example 2 are copper powder.

[0077] Table 4 Effect of different proportions of flaky alumina, nano-zinc oxide and metal copper particles on the performance of ceramics in Comparative Example 2

[0078]

[0079] The volume of the sample after sintering with the addition of metal copper particles expands to a certain extent, and the compressive strength and fracture toughness of sample 24 decrease compared with sample 17. This is because the metal copper particles will be oxidized to form copper oxide during the sintering process, which causes volume expansion, and the interlayer plastic metal phase cannot play the role of "mud" structure, so the compressive strength and fracture toughness of the ceramic sample decrease to a certain extent. Metal molybdenum particles have certain high-temperature oxidation resistance, so metal molybdenum particles are the best choice as "mud" structure.

[0080] Comparative Example 3

[0081] Comparative Example 3 differs from Example 1 in that no dispersant is added.

[0082] The honeycomb ceramic sample without dispersant incorporation fails to be extruded, showing discontinuous wall surface and large difference in extrusion speed in different areas. This is because the flaky alumina is easy to agglomerate, and the unevenly dispersed flaky alumina leads to uneven distribution of the extruded mud, and the extrusion is difficult due to different stress in the mold.

[0083] It should be noted that the above examples are merely examples for clearly illustrating the present application, and are not intended to limit the embodiments of the present application. Based on the above description, other different forms of changes or variations can be made by those of ordinary skill in the art. Here, it is impossible to exhaust all the embodiments. Any obvious changes or variations derived from the technical solutions of the present application are still within the scope of protection of the present application.

Claims

1. A method for preparing honeycomb ceramics, characterized in that, A composite additive is added to the mixed ceramic raw material, wherein the weight ratio of the mixed ceramic raw material to the composite additive is (30-50):(50-70). The composite additive includes 30-54 parts of flake alumina, 2-10 parts of nano zinc oxide and 1-5 parts of metallic molybdenum particles. The mixture is obtained by ball milling, kneading, refining, extrusion molding, drying and sintering.

2. The method for preparing honeycomb ceramics according to claim 1, characterized in that, The composite additive comprises 45-54 parts of flake alumina, 4-10 parts of nano zinc oxide, and 1-5 parts of metallic molybdenum particles.

3. The method for preparing honeycomb ceramics according to claim 1, characterized in that, The composite additive comprises 48-54 parts of flake alumina, 4-8 parts of nano zinc oxide, and 2-4 parts of metallic molybdenum particles.

4. The method for preparing honeycomb ceramics according to claim 1, characterized in that, The thickness of the sheet-like alumina is 0.2–0.4 mm, the equivalent diameter is 3–5 mm, the particle size of the nano-zinc oxide is 20–40 mm, and the particle size of the metallic molybdenum particles is 5–10 mm.

5. The method for preparing honeycomb ceramics according to any one of claims 1 to 4, characterized in that, The mixed ceramic raw material is a cordierite-mullite multiphase honeycomb ceramic raw material.

6. The method for preparing honeycomb ceramics according to claim 5, characterized in that, The mixed ceramic raw materials include the following raw materials in parts by weight: 2-7 parts cordierite, 1-4 parts kaolinite, 0.5-1.5 parts calcined alumina, 20-35 parts mullite, 2-5 parts potassium feldspar, 3-9 parts raw talc, 0.2-0.5 parts dispersant, and 0.2-0.5 parts grinding aid.

7. The method for preparing honeycomb ceramics according to claim 6, characterized in that, The dispersant is sodium dodecyl sulfate.

8. The method for preparing honeycomb ceramics according to claim 6, characterized in that, The grinding aid is glycerin.

9. The method for preparing honeycomb ceramics according to claim 6, characterized in that, The specific steps are as follows: S1. Weigh each raw material according to the weight parts and ball mill to obtain a mixture; S2. Add cellulose, lubricant, plasticizer and water to the mixture, and knead to obtain kneaded mud segments; S3. Refine the kneaded clay segments to obtain refined clay segments; S4. Place the refined clay segments into a mold and extrude them to obtain a wet blank; S5. Dry the wet blank to obtain a dry blank; S6. Cut both ends of the dry blank to obtain the cut dry blank; S7. The cut dry blanks are fired to obtain the finished ceramic product.

10. The method for preparing honeycomb ceramics according to claim 9, characterized in that, The length of the mold described in S4 is 16–40 mm.

11. The method for preparing honeycomb ceramics according to claim 10, characterized in that, The length of the mold described in S4 is 22-26 mm.

12. The method for preparing honeycomb ceramics according to claim 9, characterized in that, In S1, the raw materials other than the flaky alumina are ball-milled for 2-4 hours, and then the flaky alumina is added and ball-milled for another 2-4 hours at a speed of 200-400 revolutions per minute. After ball milling, a mixture is obtained.

13. A honeycomb ceramic prepared by the preparation method according to any one of claims 1 to 12.

14. The honeycomb ceramic according to claim 13, characterized in that, The compressive strength of the honeycomb ceramic is 130~195MPa, and the fracture toughness is 6~9MPa•m. 1 / 2 .

15. The honeycomb ceramic according to claim 13, characterized in that, The compressive strength of the honeycomb ceramic is 160~195MPa, and the fracture toughness is 8~9MPa•m. 1 / 2 .

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