Silicon carbide ceramic product and preparation process thereof

Abstract

The invention relates to the field of ceramics, in particular to a silicon carbide ceramic product and a preparation technology thereof.The silicon carbide ceramic product is prepared from modified silicon carbide, erbium oxide and betaine; the prepared silicon carbide ceramic has high bending strength and high toughness, the conditions of edge breakage, fragmentation and the like are not prone to occurring in the preparation process, and the product is stable in effect and low in defective rate.

Description

Technical Field

[0001] The present invention relates to the field of ceramics, and particularly to a silicon carbide ceramic product and a preparation process thereof. Background Art

[0002] As a high-performance material, silicon carbide ceramic products have many advantages. First, they have excellent high-temperature performance. The melting point of silicon carbide ceramics is as high as 2700 °C, and they can maintain their structural stability and strength in extremely high-temperature environments. Therefore, they are widely used in high-temperature molten metals, high-temperature heating furnaces, high-temperature petrochemical industries, etc. Their high-temperature strength can be maintained up to 1600 °C, and they have a small high-temperature creep, showing excellent high-temperature creep resistance. Second, they have strong corrosion resistance. Silicon carbide ceramics have excellent corrosion resistance and can work stably in acidic, alkaline, and oxidizing environments for a long time, showing high chemical stability. Third, they have high hardness and high strength. The hardness and strength of silicon carbide ceramics are higher than those of traditional ceramic materials, so they have good wear resistance and impact resistance. Their hardness is second only to diamond and boron carbide, making them ideal materials for manufacturing highly wear-resistant components. Fourth, they have excellent thermal conductivity and electrical conductivity. Silicon carbide ceramics have high thermal conductivity, which is conducive to the rapid transfer and dissipation of heat. In addition, the incorporation of a small amount of impurities shows good electrical conductivity, enabling silicon carbide ceramics to also have wide applications in the field of electronic components. They have a low coefficient of thermal expansion and excellent thermal shock resistance. Their low density and high elastic modulus give silicon carbide ceramics certain advantages in lightweight design. Their resistivity characteristics can be tailored and can be used as semiconductor materials. Because of the above advantages, silicon carbide ceramics are used as high-temperature kiln furniture materials in industries such as high-grade daily-use ceramics, sanitary ceramics, high-voltage electrical ceramics, and glass; they are used as the main materials for heat engine components in rockets, airplanes, automotive engines, and gas turbines; and they are considered to be one of the most promising high-performance bulletproof armor materials and are increasingly widely used in the field of armor protection.

[0003] Although silicon carbide ceramic products have various advantages, they also have obvious defects. For example, the fracture toughness of silicon carbide ceramic products is relatively low, that is, they are relatively brittle. This limits their applications in some precision mechanical components, aerospace fields, automotive industries, and applications in the electronic and electrical fields that are sensitive to impact and vibration. Moreover, the high hardness and brittleness of silicon carbide ceramics make their processing difficult, and situations such as chipping and cracking are likely to occur. Therefore, it is relatively difficult to manufacture silicon carbide ceramic products with relatively complex shapes. Summary of the Invention

[0004] To solve the deficiencies of the prior art, the present invention provides a silicon carbide ceramic product and a preparation process thereof.

[0005] A silicon carbide ceramic product, characterized in that the raw materials of the silicon carbide ceramic product include modified silicon carbide, erbium oxide, and betaine, and the raw materials for preparing the modified silicon carbide include carbon fiber, concentrated acid, benzoic acid, benzotrichloride, alkali solution, catalyst, ethanol, and fuming sulfuric acid.

[0006] Preferably, the mass ratio of modified silicon carbide, erbium oxide, and betaine is (20 - 30):(1 - 3):(0.5 - 1).

[0007] Preferably, the preparation steps of the modified silicon carbide include:

[0008] S1: Place silicon carbide in a closed container and soak it in concentrated sulfuric acid solution. Under process condition 1, filter it to obtain intermediate 1;

[0009] S2: Place carbon fiber in a closed container and soak it in sodium hydroxide solution. Under process condition 2, filter it to obtain intermediate 2;

[0010] S3: Put benzoic acid, benzotrichloride, and catalyst 1 into a reaction kettle. Under process condition 3, after the reaction, then put benzene and catalyst 2 into the reaction kettle. Under process condition 4, after purification, obtain intermediate 3;

[0011] S4: Put intermediate 3 into a container, add 7 - 10% fuming sulfuric acid, set process condition 5. After the reaction is completed, add sodium hydroxide solution, set process condition 6, and after the reaction, purify to obtain intermediate 4;

[0012] S5: Put intermediate 1, intermediate 2, intermediate 4, and ethanol into a reaction kettle, set process condition 7, and after purification, obtain intermediate 5;

[0013] S6: Put concentrated nitric acid into a container. After the mixed acid is cooled, add intermediate 5 to generate modified silicon carbide.

[0014] Preferably, process condition 1 is that the soaking time is 1 - 3 h and the soaking temperature is 90 - 110 °C; process condition 2 is that the soaking time is 1.5 - 4 h and the soaking temperature is 100 - 120 °C; process condition 3 is that the temperature is 80 - 130 °C and the time is 0.5 - 2 h, process condition 4 is that the temperature is 60 °C - 80 °C and the time is 0.5 - 2 h; process condition 5 is that the treatment temperature is between 60 - 75 °C and the reaction is 0.5 h - 2 h; process condition 6 is that the temperature is 200 - 240 °C and the time is 0.5 - 2 h, process condition 7 is 50 - 80 °C, 0.2 - 2 h; the cooling temperature in step S6 is below 60 °C.

[0015] Preferably, in step S5, the weight ratio of intermediate 1, intermediate 2, intermediate 4, and ethanol is (7 - 10):(1 - 2):(9 - 12):(20 - 30).

[0016] Preferably, the weight ratio of benzoic acid, benzotrichloride, and catalyst 1 in step S3 is (5-8):(5-12):(8-12).

[0017] Preferably, catalyst 1 is one or more of zinc chloride, aluminum trichloride, or ferric trichloride; catalyst 2 is one or more of aluminum chloride, ferric chloride, or azobisisobutyronitrile.

[0018] Preferably, the steps of the preparation process include:

[0019] T1: Place silicon carbide in a sealed container, soak it in concentrated sulfuric acid solution, and filter under process condition 1 to obtain intermediate 1;

[0020] T2: Place carbon fiber in a sealed container, soak it in sodium hydroxide solution, and filter under process condition 2 to obtain intermediate 2;

[0021] T3: Put benzoic acid, benzotrichloride, and catalyst 1 into a reaction kettle, react under process condition 3, and then put benzene and catalyst 2 into the reaction kettle. Under process condition 4, after purification, intermediate 3 is obtained;

[0022] T4: Put intermediate 3 into a container, add 7-10% fuming sulfuric acid, set process condition 5, and after the reaction is completed, add sodium hydroxide solution, set process condition 6, and after the reaction, purify to obtain intermediate 4;

[0023] T5: Put intermediate 1, intermediate 2, intermediate 4, and ethanol into a reaction kettle, set process condition 7, and after purification, intermediate 5 is obtained;

[0024] T6: Pour concentrated nitric acid into a container. After the mixed acid is cooled, add intermediate 5 to generate modified silicon carbide;

[0025] T7: Put the modified silicon carbide, erbium oxide, and betaine into a cast steel mold, and under process condition 7, press the powder into a green body;

[0026] T8: Put the pressed green body into a sintering furnace for sintering, evacuate and fill with argon, and under process condition 8, obtain silicon carbide ceramic products.

[0027] Preferably, Process Condition 1 is that the soaking time is 1 - 3 h and the soaking temperature is 90 - 110 °C; Process Condition 2 is that the soaking time is 1.5 - 4 h and the soaking temperature is 100 - 120 °C; Process Condition 3 is that the temperature is 80 - 130 °C and the time is 0.5 - 2 h; Process Condition 4 is that the temperature is 60 °C - 80 °C and the time is 0.5 - 2 h; Process Condition 5 is that the treatment temperature is between 60 - 75 °C and the reaction is for 0.5 h - 2 h; Process Condition 6 is 50 - 80 °C and 0.2 - 2 h; the cooling temperature in Step S6 is below 60 °C; Process Condition 7 is that the temperature is 200 - 240 °C and the time is 0.5 - 2; Process Condition 8 is 150 - 170 MPa and the pressure holding time is 10 s - 60 s; Process Condition 9 is that the sintering furnace is a non - pressure sintering furnace, its heating rate is 10 - 30 °C / min, the sintering temperature is controlled at 2000 - 2200 °C, and the heat preservation time is 30 - 40 min.

[0028] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0029] The silicon carbide ceramic prepared by the present invention not only has high flexural strength but also high toughness. During the preparation process, it is not easy to have situations such as chipping and cracking, and the effect of the product is stable with a low defective product rate. Specific Embodiments

[0030] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0031] Example 1:

[0032] T1: Place silicon carbide in a closed container and soak it in a concentrated nitric acid solution for 1 h at a soaking temperature of 90 °C, and obtain Intermediate 1 by suction filtration;

[0033] T2: Place 600 - mesh carbon fiber in a closed container and soak it in a sodium hydroxide solution for 1.5 h at a soaking temperature of 100 °C, and obtain Intermediate 2 by suction filtration;

[0034] T3: Put 5 parts of benzoic acid, 5 parts of benzotrichloride and 0.2 part of zinc chloride into a reaction kettle, react at a temperature of 80 °C for 0.5 h, and then put 9 parts of benzene and 0.2 part of aluminum chloride into the reaction kettle at a temperature of 60 °C for 0.5 h. After purification, Intermediate 3 is obtained;

[0035] T4: Add the intermediate 3 into a container, and then add 7% fuming sulfuric acid. React at 60 °C for 0.5 h. After the reaction is completed, add a sodium hydroxide solution with a mass fraction of 20%, and react at 50 °C for 0.5 h. After the reaction, purify to obtain intermediate 4;

[0036] T5: Add 7 parts of intermediate 1, 1 part of intermediate 2, 9 parts of intermediate 4, and 20 parts of ethanol into a reaction kettle. React at 50 °C for 0.2 h. After purification, obtain intermediate 5;

[0037] T6: Pour concentrated nitric acid into a container. After the mixed acid is cooled below 60 °C, add intermediate 5 to generate modified silicon carbide;

[0038] T7: Add 20 parts of modified silicon carbide, 1 part of erbium oxide, and 0.5 part of betaine into a steel mold for hub bearings, and apply 150 MPa. Keep the pressure for 10 s, and form the powder into a green body;

[0039] T8: Put the formed green body into a non-pressure sintering furnace for sintering. Evacuate and fill with argon. The heating rate is 10 °C / min, the sintering temperature is controlled at 2000 °C, and the heat preservation time is 30 min to obtain silicon carbide ceramic products.

[0040] Example 2:

[0041] T1: Place silicon carbide in a sealed container and soak it in a concentrated sulfuric acid solution for 3 h at a soaking temperature of 110 °C. Filter by suction to obtain intermediate 1;

[0042] T2: Place 800-mesh carbon fiber in a sealed container and soak it in a sodium hydroxide solution for 4 h at a soaking temperature of 120 °C. Filter by suction to obtain intermediate 2;

[0043] T3: Add 8 parts of benzoic acid, 12 parts of benzotrichloride, and 0.5 part of aluminum trichloride into a reaction kettle. React at 130 °C for 2 h. After the reaction, add 12 parts of benzene and 0.5 part of azobisisobutyronitrile into the reaction kettle. React at 80 °C for 2 h. After purification, obtain intermediate 3;

[0044] T4: Add the intermediate 3 into a container, and then add 10% fuming sulfuric acid. React at 75 °C for 2 h. After the reaction is completed, add a sodium hydroxide solution with a mass fraction of 30% and react at 80 °C for 2 h. After the reaction, purify to obtain intermediate 4;

[0045] T5: Add 10 parts of intermediate 1, 2 parts of intermediate 2, 12 parts of intermediate 4, and 30 parts of ethanol into a reaction kettle. React at 80 °C for 2 h. After purification, obtain intermediate 6;

[0046] T6: Concentrated nitric acid is put into a container. After the mixed acid is cooled below 60°C, intermediate 6 is added to produce modified silicon carbide;

[0047] T7: 30 parts of modified silicon carbide, 3 parts of erbium oxide, and 1 part of betaine are put into a steel mold for hub bearings, and 170 MPa is applied. The powder is formed into a green body under a holding pressure time of 60 s;

[0048] T8: The green body formed by pressing is put into a pressureless sintering furnace for sintering. Vacuum is pumped and argon is filled. The heating rate is 30°C / min, the sintering temperature is controlled at 2200°C, and the holding time is 40 min to obtain silicon carbide ceramic products.

[0049] Example 3:

[0050] T1: Silicon carbide is placed in a closed container and soaked in concentrated sulfuric acid solution for 2 h at an immersion temperature of 100°C. After suction filtration, intermediate 1 is obtained;

[0051] T2: 700-mesh carbon fiber is placed in a closed container and soaked in sodium hydroxide solution for 3 h at an immersion temperature of 110°C. After suction filtration, intermediate 2 is obtained;

[0052] T3: 7 parts of benzoic acid, 10 parts of benzotrichloride, 0.2 part of zinc chloride, and 0.2 part of ferric chloride are put into a reaction kettle. The reaction is carried out at a temperature of 120°C for 1 h. After the reaction, 10 parts of benzene, 0.2 part of ferric chloride, and 0.1 part of azobisisobutyronitrile are put into the reaction kettle. The reaction is carried out at a temperature of 70°C for 1 h. After purification, intermediate 3 is obtained;

[0053] T4: Intermediate 3 is put into a container, and 9% oleum is added. The reaction is carried out at a temperature of 70°C for 0.9 h. After the reaction is completed, a sodium hydroxide solution with a mass fraction of 25% is added. Under the conditions of 70°C and 1 h, after the reaction, purification is carried out to obtain intermediate 4;

[0054] T5: 8 parts of intermediate 1, 1.3 parts of intermediate 2, 11 parts of intermediate 4, and 23 parts of ethanol are put into a reaction kettle. The reaction is carried out at a temperature of 60°C for 0.9 h. After purification, intermediate 5 is obtained;

[0055] T6: Concentrated nitric acid is put into a container. After the mixed acid is cooled below 60°C, intermediate 5 is added to produce modified silicon carbide;

[0056] T7: 25 parts of modified silicon carbide, 2 parts of erbium oxide, and 0.7 part of betaine are put into a steel mold for hub bearings, and 150 MPa is applied. The powder is formed into a green body under a holding pressure time of 50 s;

[0057] T8: Place the pressed green body into a pressureless sintering furnace for sintering. Evacuate and fill with argon. The heating rate is 20 °C / min, the sintering temperature is controlled at 2100 °C, and the holding time is 35 min to obtain a silicon carbide ceramic product.

[0058] Comparative Example 1:

[0059] T1: Place 700-mesh carbon fiber in a sealed container and soak it in sodium hydroxide solution for 3 h at a soaking temperature of 110 °C. Filter by suction to obtain Intermediate 1;

[0060] T2: Put 7 parts of benzoic acid, 10 parts of benzotrichloride, 0.2 part of zinc chloride, and 0.2 part of ferric chloride into a reaction kettle. React at a temperature of 120 °C for 1 h. After the reaction, put 10 parts of benzene, 0.2 part of ferric chloride, and 0.1 part of azobisisobutyronitrile into the reaction kettle. React at a temperature of 70 °C for 1 h and obtain Intermediate 2 after purification;

[0061] T3: Put Intermediate 2 into a container, add 9% fuming sulfuric acid, react at 70 °C for 0.9 h. After the reaction is completed, add 25% sodium hydroxide solution by mass. React at 70 °C for 1 h and obtain Intermediate 3 after purification;

[0062] T4: Put 8 parts of silicon carbide, 1.3 parts of Intermediate 1, 11 parts of Intermediate 3, and 23 parts of ethanol into a reaction kettle. React at a temperature of 60 °C for 0.9 h and obtain Intermediate 4 after purification;

[0063] T5: Pour concentrated nitric acid into a container. After the mixed acid is cooled below 60 °C, add Intermediate 4 to produce modified silicon carbide;

[0064] T6: Put 25 parts of modified silicon carbide, 2 parts of erbium oxide, and 0.7 part of betaine into a hub bearing cast steel mold, apply 150 MPa, and press the powder into a green body under a holding time of 50 s;

[0065] T7: Place the pressed green body into a pressureless sintering furnace for sintering. Evacuate and fill with argon. The heating rate is 20 °C / min, the sintering temperature is controlled at 2100 °C, and the holding time is 35 min to obtain a silicon carbide ceramic product.

[0066] Comparative Example 2:

[0067] T1: Place silicon carbide in a sealed container and soak it in concentrated sulfuric acid solution for 2 h at a soaking temperature of 100 °C. Filter by suction to obtain Intermediate 1;

[0068] T2: Put 7 parts of benzoic acid, 10 parts of benzotrichloride, 0.2 part of zinc chloride, and 0.2 part of ferric chloride into a reaction kettle. React at a temperature of 120 °C for 1 h. After the reaction, put 10 parts of benzene, 0.2 part of ferric chloride, and 0.1 part of azodiisobutyronitrile into the reaction kettle. React at a temperature of 70 °C for 1 h. After purification, intermediate 2 is obtained;

[0069] T3: Put intermediate 2 into a container, and add 9% oleum. React at a temperature of 70 °C for 0.9 h. After the reaction is completed, add a 25% sodium hydroxide solution. React at 70 °C for 1 h. After the reaction, intermediate 3 is obtained through purification;

[0070] T4: Put 8 parts of intermediate 1, 11 parts of intermediate 3, and 23 parts of ethanol into a reaction kettle. React at a temperature of 60 °C for 0.9 h. After purification, intermediate 4 is obtained;

[0071] T5: Put concentrated nitric acid into a container. After the mixed acid is cooled below 60 °C, add intermediate 4 to generate modified silicon carbide;

[0072] T6: Put 25 parts of modified silicon carbide, 2 parts of erbium oxide, and 0.7 part of betaine into a steel mold for hub bearings, and apply 150 MPa. Keep the pressure for 50 s to form and press the powder into a green body;

[0073] T7: Put the formed green body into a non-pressure sintering furnace for sintering. Evacuate and fill with argon. The heating rate is 20 °C / min. The sintering temperature is controlled at 2100 °C, and the holding time is 35 min to obtain silicon carbide ceramic products.

[0074] Comparative Example 3:

[0075] T1: Put silicon carbide into a sealed container and soak it in concentrated sulfuric acid solution for 2 h at a soaking temperature of 100 °C. Filter with suction to obtain intermediate 1;

[0076] T2: Put 700-mesh carbon fiber into a sealed container and soak it in sodium hydroxide solution for 3 h at a soaking temperature of 110 °C. Filter with suction to obtain intermediate 2;

[0077] T3: Put 7 parts of benzoic acid, 10 parts of benzotrichloride, 0.2 part of zinc chloride, and 0.2 part of ferric chloride into a reaction kettle. React at a temperature of 120 °C for 1 h. After the reaction, put 10 parts of benzene, 0.2 part of ferric chloride, and 0.1 part of azodiisobutyronitrile into the reaction kettle. React at a temperature of 70 °C for 1 h. After purification, intermediate 3 is obtained;

[0078] T4: Put the intermediate 3 into a container, add 9% fuming sulfuric acid, react at 70 °C for 0.9 h. After the reaction is completed, add a 25% sodium hydroxide solution by mass, and react at 70 °C for 1 h. After the reaction, purify to obtain intermediate 4;

[0079] T5: Put 8 parts of intermediate 1, 1.3 parts of intermediate 2, 11 parts of intermediate 4, and 23 parts of ethanol into a reaction kettle, react at 60 °C for 0.9 h, and obtain modified silicon nitride after purification;

[0080] T6: Put 25 parts of modified silicon carbide, 2 parts of erbium oxide, and 0.7 part of betaine into a steel mold for hub bearings, apply 150 MPa, and compact the powder into a green body under a holding pressure time of 50 s;

[0081] T8: Put the green body formed by pressing into a pressureless sintering furnace for sintering, evacuate and fill with argon, the heating rate is 20 °C / min, the sintering temperature is controlled at 2100 °C, and the holding time is 35 min to obtain silicon carbide ceramic products.

[0082] Comparative Example 4:

[0083] T1: Put silicon carbide into a closed container, soak it in concentrated sulfuric acid solution for 2 h at an immersion temperature of 100 °C, and obtain intermediate 1 by suction filtration;

[0084] T2: Put 700-mesh carbon fiber into a closed container, soak it in sodium hydroxide solution for 3 h at an immersion temperature of 110 °C, and obtain intermediate 2 by suction filtration;

[0085] T3: Put 7 parts of benzoic acid, 10 parts of benzotrichloride, 0.2 part of zinc chloride, and 0.2 part of ferric chloride into a reaction kettle, react at 120 °C for 1 h. After the reaction, put 10 parts of benzene, 0.2 part of ferric chloride, and 0.1 part of azobisisobutyronitrile into the reaction kettle, react at 70 °C for 1 h, and obtain intermediate 3 after purification;

[0086] T4: Put the intermediate 3 into a container, add 9% fuming sulfuric acid, react at 70 °C for 0.9 h. After the reaction is completed, add a 25% sodium hydroxide solution by mass, and react at 70 °C for 1 h. After the reaction, purify to obtain intermediate 4;

[0087] T5: Put 12 parts of intermediate 1, 1 part of intermediate 2, 11 parts of intermediate 4, and 23 parts of ethanol into a reaction kettle, react at 60 °C for 0.9 h, and obtain intermediate 5 after purification;

[0088] T6: Pour concentrated nitric acid into a container. After cooling the mixed acid below 60 °C, add intermediate 5 to produce modified silicon carbide;

[0089] T7: Put 25 parts of modified silicon carbide, 2 parts of erbium oxide, and 0.7 part of betaine into a steel casting mold for hub bearings, apply 150 MPa, and compact the powder into a green body under a holding pressure time of 50 s;

[0090] T8: Put the compacted green body into a pressureless sintering furnace for sintering, evacuate and fill with argon, with a heating rate of 20 °C / min, control the sintering temperature at 2100 °C, and hold for 35 min to obtain silicon carbide ceramic products.

[0091] Comparative Example 5:

[0092] T1: Place silicon carbide in a closed container, soak it in concentrated sulfuric acid solution for 2 h at a soaking temperature of 100 °C, and filter to obtain Intermediate 1;

[0093] T2: Place 700-mesh carbon fiber in a closed container, soak it in sodium hydroxide solution for 3 h at a soaking temperature of 110 °C, and filter to obtain Intermediate 2;

[0094] T3: Put 7 parts of benzoic acid, 10 parts of benzotrichloride, 0.2 part of zinc chloride, and 0.2 part of ferric chloride into a reaction kettle, react at a temperature of 120 °C for 1 h. After the reaction, put 10 parts of benzene, 0.2 part of ferric chloride, and 0.1 part of azobisisobutyronitrile into the reaction kettle, react at a temperature of 70 °C for 1 h, and obtain Intermediate 3 after purification;

[0095] T4: Put Intermediate 3 into a container, add 9% fuming sulfuric acid, react at 70 °C for 0.9 h. After the reaction is completed, add 25% sodium hydroxide solution by mass, react at 70 °C for 1 h, and obtain Intermediate 4 after purification;

[0096] T5: Put 8 parts of Intermediate 1, 1.3 parts of Intermediate 2, 11 parts of Intermediate 4, and 23 parts of ethanol into a reaction kettle, react at a temperature of 60 °C for 0.9 h, and obtain Intermediate 5 after purification;

[0097] T6: Pour concentrated nitric acid into a container. After cooling the mixed acid below 60 °C, add Intermediate 5 to generate modified silicon carbide;

[0098] T7: Put 25 parts of modified silicon carbide and 2 parts of erbium oxide into a steel casting mold for hub bearings, apply 150 MPa, and compact the powder into a green body under a holding pressure time of 50 s;

[0099] T8: Place the compacted green body into a pressureless sintering furnace for sintering. Evacuate and fill with argon. The heating rate is 20 °C / min, the sintering temperature is controlled at 2100 °C, and the holding time is 35 min to obtain silicon carbide ceramic products.

[0100] Comparative Example 6: Place the untreated silicon carbide wheel hub bearing steel mold, apply 150 MPa, and compact the powder into a green body under a holding pressure time of 50 s.

[0101] T8: Place the compacted green body into a pressureless sintering furnace for sintering. Evacuate and fill with argon. The heating rate is 20 °C / min, the sintering temperature is controlled at 2100 °C, and the holding time is 35 min to obtain silicon carbide ceramic products.

[0102] Prepare 10 pieces for each of Examples 1-3 and Comparative Examples 1-6. Install the ceramic products prepared in Examples 1-3 and Comparative Examples 1-5 at the rim bearing position and run for 48 h at a rotational speed of 500 - 1000 r / min. After the operation, observe the appearance and qualification rate of the products.

[0103] Test the hardness, flexural strength, and fracture toughness of the silicon carbide prepared in Examples 1-3 and Comparative Examples 1-6.

[0104] Table 1 Test Results

[0105]

[0106] It can be seen from the test results that

[0107] Compared with Comparative Example 6, the flexural strength of Examples 1-3 is increased by about 25%, the fracture toughness is about 2 times higher, and 90 - 100% of the products are qualified, showing a very large improvement in the product qualification rate.

[0108] Compared with Comparative Example 1, the flexural strength of Examples 1-3 is increased by about 33%, the fracture toughness is about 1 time higher, and the product qualification rate has been greatly improved.

[0109] Compared with Comparative Example 2, the flexural strength of Examples 1-3 is increased by about 10%, the fracture toughness is about 30% higher, and the product qualification rate has been greatly improved.

[0110] Compared with Comparative Example 3, the flexural strength of Examples 1-3 is increased by about 5%, the fracture toughness is about 10% higher, and the product qualification rate has been greatly improved.

[0111] Compared with Comparative Example 4, the flexural strength of Examples 1-3 is increased by about 10%, the fracture toughness is about 20% higher, and the product qualification rate has been greatly improved.

[0112] Compared with Comparative Example 5, the flexural strength in Examples 1-3 is increased by about 5%, the fracture toughness is about 30% higher, and the qualified rate of products has been greatly improved.

[0113] Although the embodiments of the present invention have been shown and described (see the above detailed description), for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A silicon carbide ceramic product, characterized in that: The raw materials of the silicon carbide ceramic product include modified silicon carbide, erbium oxide and betaine, and the raw materials for preparing the modified silicon carbide include carbon fiber, concentrated acid, benzoic acid, trichlorotoluene, alkaline solution, catalyst, ethanol and fuming sulfuric acid.

2. A silicon carbide ceramic product according to claim 1, characterized in that: The preparation steps of the modified silicon carbide include: S1: Place silicon carbide in a sealed container and soak it in concentrated sulfuric acid solution, and filter and obtain intermediate 1 under process condition 1; S2: placing the carbon fiber in a sealed container and soaking it in a sodium hydroxide solution, and filtering it under process condition 2 to obtain intermediate 2; S3: adding benzoic acid, trichlorotoluene and catalyst 1 into a reactor, reacting under process condition 3, and then adding benzene and catalyst 2 into the reactor after the reaction, and obtaining intermediate 3 after purification under process condition 4; S4: putting the intermediate 3 into a container, adding 7-10% fuming sulfuric acid, setting process condition 5, adding sodium hydroxide solution after the reaction is completed, setting process condition 6, and purifying after the reaction to obtain the intermediate 4; S5: putting intermediate 1, intermediate 2, intermediate 4 and ethanol into a reactor, setting process condition 7, and obtaining intermediate 5 after purification; S6: Concentrated nitric acid is added into the container, and after the mixed acid is cooled, the intermediate 5 is added to generate modified silicon carbide.

3. A silicon carbide ceramic product according to claim 2, characterized in that: The process condition 1 is that the soaking time is 1-3h and the soaking temperature is 90-110℃; the process condition 2 is that the soaking time is 1.5-4h and the soaking temperature is 100-120℃; the process condition 3 is that the temperature is 80-130℃ and the time is 0.5-2h, and the process condition 4 is that the temperature is 60℃-80℃ and the time is 0.5-2h; the process condition 5 is that the treatment temperature is between 60-75℃ and the reaction time is 0.5h-2h; the process condition 6 is that the temperature is 200-240℃ and the time is 0.5-2h, and the process condition 7 is 50-80℃, 0.2-2h; the cooling temperature of the mixed acid cooling in step S6 is below 60℃.

4. A silicon carbide ceramic product according to claim 2, characterized in that: In the step S5, the weight ratio of intermediate 1, intermediate 2, intermediate 4 and ethanol is (7-10): (1-2): (9-12): (20-30).

5. The silicon carbide ceramic product according to claim 2, characterized in that: In the step S3, the weight ratio of benzoic acid, trichlorotoluene and catalyst 1 is (5-8): (5-12): (8-12).

6. The silicon carbide ceramic product according to claim 2, characterized in that: The catalyst 1 is one or more of zinc chloride, aluminum chloride or ferric chloride; the catalyst 2 is one or more of aluminum chloride, ferric chloride or azobisisobutyronitrile.

7. A process for preparing a silicon carbide ceramic product as claimed in any one of claims 1 to 6, characterized in that: The steps of the preparation process include: T1: Place silicon carbide in a sealed container and soak it in concentrated sulfuric acid solution. Under process condition 1, filter and obtain intermediate 1; T2: placing the carbon fiber in a sealed container and soaking it in a sodium hydroxide solution, and filtering it under process condition 2 to obtain intermediate 2; T3: Add benzoic acid, trichlorotoluene and catalyst 1 into a reactor and react under process condition 3. After the reaction, add benzene and catalyst 2 into the reactor and purify under process condition 4 to obtain intermediate 3. T4: put the intermediate 3 into a container, add 7-10% fuming sulfuric acid, set process condition 5, add sodium hydroxide solution after the reaction is completed, set process condition 6, and purify after the reaction to obtain the intermediate 4; T5: intermediate 1, intermediate 2, intermediate 4 and ethanol are added to a reactor, process condition 7 is set, and intermediate 5 is obtained after purification; T6: concentrated nitric acid is added into the container, and after the mixed acid is cooled, intermediate 5 is added to generate modified silicon carbide; T7: Put modified silicon carbide, erbium oxide and betaine into a cast steel mold, and press the powder into a green billet under process condition 8; T8: The pressed green blank is placed in a sintering furnace for sintering, vacuumed and filled with argon, and a silicon carbide product is obtained under process condition 9.

8. The preparation process according to claim 7, characterized in that: The process condition 1 is that the soaking time is 1-3h and the soaking temperature is 90-110℃; the process condition 2 is that the soaking time is 1.5-4h and the soaking temperature is 100-120℃; the process condition 3 is that the temperature is 80-130℃ and the time is 0.5-2h; the process condition 4 is that the temperature is 60℃-80℃ and the time is 0.5-2h; the process condition 5 is that the treatment temperature is between 60-75℃ and the reaction time is 0.5h-2h; the process condition 6 is that the temperature is The process condition 9 is that the sintering furnace is a pressureless sintering furnace, the heating rate is 10-30°C / min, the sintering temperature is controlled at 2000-2200°C, and the holding time is 30-40min.

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