High-performance ceramic cutter head and forming method thereof

Abstract

The application provides a high-performance ceramic cutter head and a forming method thereof, and relates to the technical field of cutter heads.The ceramic cutter head comprises, by weight, 5-7 parts of a nano-composite powder, 3-6 parts of silicon carbide whiskers, 25-35 parts of titanium boride, 65-75 parts of aluminum oxide and 1-2 parts of a sintering aid;the matrix of the nano-composite powder is a carbon nanotube, and the surface of the carbon nanotube matrix is sequentially modified with a first coating layer and a second coating layer;the first coating layer is a carbon-nitrogen coating layer, and the second coating layer is an in-situ grown silicon carbide layer.The method is simple to operate, and the ceramic cutter prepared by optimizing the preparation process conditions has high hardness and excellent mechanical properties.

Description

Technical Field

[0001] This invention relates to the field of cutting tool manufacturing technology, specifically to a high-performance ceramic cutter disc and its forming method. Background Technology

[0002] The ceramic burr is one of the core components of a coffee grinder, primarily used to grind coffee beans into uniform particles. A ceramic burr typically consists of two circular grinding discs: a stationary disc mounted at the bottom of the grinder, and a rotating disc connected to a motor or manual spindle that rotates at high speed to cut the coffee beans.

[0003] Currently, most ceramic cutter heads are made of zirconia ceramic, which has the following advantages: 1. High hardness and good wear resistance; 2. Low thermal conductivity, which effectively reduces heat accumulation during grinding, thus protecting coffee flavor; 3. Resistance to acid and alkali corrosion, not easy to rust, and does not absorb coffee oils, avoiding odor residue. However, zirconia ceramic cutter heads also have many disadvantages, such as: high brittleness, easily broken by external impact, and difficulty in meeting the high-speed processing requirements of difficult-to-machine materials. Therefore, providing new ceramic cutter head materials is of great significance. Summary of the Invention

[0004] One of the technical problems to be solved by the present invention is to provide a high-performance ceramic cutter disc, which not only has high hardness but also excellent mechanical properties.

[0005] The second technical problem to be solved by the present invention is to provide a method for forming a high-performance ceramic cutter head. This method is simple to operate and, by optimizing the preparation process conditions, produces ceramic cutters with excellent comprehensive performance.

[0006] To solve the first technical problem mentioned above, the technical solution of the present invention is:

[0007] A high-performance ceramic cutter disc, by weight, comprises 5-7 parts of nanocomposite powder, 3-6 parts of silicon carbide whiskers, 25-35 parts of titanium boride, 65-75 parts of alumina, and 1-2 parts of sintering aid.

[0008] The matrix of the nanocomposite powder is carbon nanotubes, and the surface of the carbon nanotube matrix is ​​sequentially modified with a first coating and a second coating. The first coating is a carbon nitride coating, and the second coating is an in-situ grown silicon carbide layer.

[0009] Preferably, the sintering aid is a mixture of magnesium oxide and yttrium oxide, wherein the mass ratio of magnesium oxide to yttrium oxide is 1:(2-3).

[0010] Preferably, the silicon carbide whiskers are β-SiC whiskers with a diameter of 0.1-0.2 μm and a length of 10-20 μm, the titanium boride has an average particle size of 1-2 μm, the alumina has an average particle size of 1-2 μm, the magnesium oxide has a particle size of 1.5-2.5 μm, and the yttrium oxide has a particle size of 1.5-2.5 μm.

[0011] To solve the second technical problem mentioned above, the present invention provides the following technical solution:

[0012] A method for forming a high-performance ceramic cutter head includes the following steps:

[0013] (1) Carbon nanotubes are acidified to obtain acidified carbon nanotubes. Then, the acidified carbon nanotubes are added to a mixed solution of glucose and urea and ultrasonically treated. The resulting reaction solution is placed in a reaction vessel for hydrothermal reaction. After the reaction is completed, the hydrothermal reaction solution is centrifuged, the centrifuged precipitate is washed and dried to obtain pre-coated carbon nanotube material.

[0014] (2) The pre-coated carbon nanotube material is placed in a tube furnace and subjected to pyrolysis reaction to obtain the carbon nanotube material coated with the first coating.

[0015] (3) The carbon nanotube material coated with the first coating above is mixed with polycarbosilane solution, ultrasonically treated, then cured, crushed and sieved, and then placed in a tube furnace for heat treatment to obtain nanocomposite powder.

[0016] (4) According to the stoichiometric ratio, nanocomposite powder, silicon carbide whiskers, titanium boride, alumina, sintering aid and anhydrous ethanol are placed in a ball mill jar, and zirconium oxide is used as the ball milling medium for ball milling. The slurry obtained by ball milling is dried and sieved. The obtained powder is placed in a mold for pre-pressing treatment. Finally, the pre-pressed blank is hot-pressed and sintered to obtain ceramic knives.

[0017] Preferably, in step (1), the acid solution for acidification is a mixture of concentrated sulfuric acid and concentrated nitric acid, with a volume ratio of 3:1; the acidification conditions are reflux at 80°C for 3-6 hours. Preferably, in step (1), the concentration of glucose in the mixed solution is 1-20 wt%, and the mass ratio of acidified carbon nanotubes, glucose, and urea is 1:(4-5):1; the hydrothermal reaction temperature is 180-200°C, and the time is 5-6 hours.

[0018] Preferably, in steps (1) and (3), the power of ultrasonic treatment is 200-300W and the time is 20-30min;

[0019] Preferably, in step (2), the atmosphere of the pyrolysis reaction is an inert gas, the heating rate is 2-3℃ / min, the temperature is 800-900℃, and the time is 1-2h.

[0020] Preferably, in step (3), the concentration of the polycarbosilane solution is 45-50 wt%, the mass ratio of the carbon nanotube material coated by the first coating to the polycarbosilane solution is 1:1; the curing temperature is 200℃ and the time is 1-2 h; the heat treatment temperature is 1200℃, the heating rate is 4-5℃ / min, and the time is 1-2 h.

[0021] Preferably, in step (4), the ball-to-material ratio during ball milling is (10-20):1; the rotation speed of the ball mill during ball milling is 100-200 r / min; and the ball milling time is 20-30 h.

[0022] Preferably, in step (4), the pre-pressing treatment is carried out at room temperature, at a pressure of 35-40 MPa, and for a pressing time of 15-20 min.

[0023] Preferably, in step (4), the hot pressing sintering conditions are as follows: first, the temperature is raised to 700-800℃ at a rate of 90-95℃ / min, then raised to 1000-1050℃ / min at a rate of 85-88℃ / min, then raised to 1150-1200℃ / min at a rate of 65-70℃ / min, and finally raised to 1550-1580℃ at a rate of 40-43℃ / min, and held for 5-10 minutes. The pressure for hot pressing sintering is 30-40MPa.

[0024] By adopting the above technical solution, the present invention has at least the following beneficial effects:

[0025] 1. This invention modifies a ceramic matrix by incorporating nanocomposite powder. The nanocomposite powder uses carbon nanotubes as the matrix. First, a carbon-nitrogen coating is formed on the surface of the carbon nanotubes through hydrothermal treatment and pyrolysis as the first coating, which improves the chemical stability and interfacial bonding of the carbon nanotubes. Moreover, the high-temperature stability of the coating reduces the structural degradation of the carbon nanotubes during subsequent sintering. Second, this invention also uses polycarbosilane as a raw material to generate a SiC coating in situ on the surface of the first coating as the second coating, which further improves the interfacial bonding between the nanocomposite powder and the ceramic matrix, reduces interfacial stress, and improves the load transfer efficiency between the nanocomposite powder and the matrix, thereby improving the strength and toughness of the ceramic cutting tool.

[0026] 2. In this invention, silicon carbide whiskers and nanocomposite powder are added to the ceramic matrix to synergistically modify the ceramic matrix. The silicon carbide whiskers with high aspect ratio can effectively hinder crack propagation through crack deflection and bridging mechanisms, significantly improving the fracture toughness of the ceramic cutting tool. They form a three-dimensional network with the nanocomposite powder to jointly bear external stress, reduce local stress concentration in the matrix, and improve the performance of the ceramic cutting tool.

[0027] 3. In the hot-pressing sintering process for preparing ceramic cutting tools, this invention employs a staged heating method. First, the temperature is rapidly increased to a certain level. This high temperature quickly evaporates residual solvents and decomposes low-melting-point organic matter, preventing the formation of pores due to carbonization of organic matter in the subsequent high-temperature stage. Furthermore, during this rapid heating process, initial diffusion occurs on the surface of alumina and titanium boride particles, forming localized neck connections that provide skeletal support for subsequent densification. Second, during a medium-speed heating process, the sintering aids magnesium oxide and yttrium oxide form a eutectic liquid phase, wetting the particle surface, reducing interfacial energy, and promoting particle sliding and rearrangement. The reduced heating rate during this process alleviates localized thermal stress caused by rapid heating, preventing microcrack formation. Simultaneously, the liquid phase fills the pores, improving the material's density. Density; then, the heating rate is further reduced to prolong the liquid phase existence time, and the magnesium oxide-yttrium oxide-alumina system forms a continuous liquid phase network. Through the dissolution-precipitation mechanism, grain boundary migration is accelerated, closed pores are eliminated, and silicon carbide whiskers and nanocomposite powders are directionally distributed in the liquid phase, forming a strong interfacial bond with the ceramic matrix and inhibiting abnormal grain growth; finally, the heating rate is further reduced to raise the hot pressing sintering temperature to a certain temperature, and residual pores are completely eliminated through plastic flow and creep mechanisms, improving the density of the material. Moreover, the holding time is effectively optimized, limiting the grain growth time, avoiding excessive coarsening of alumina and titanium boride grains, maintaining the dispersion strengthening effect of nanocomposite powders, and retaining the toughening effect of silicon carbide whiskers. Detailed Implementation

[0028] To better understand the above-mentioned objectives, features, and advantages of the present invention, the solutions of the present invention will be further described below. It should be noted that, unless otherwise specified, the embodiments of the present invention and the features thereof can be combined with each other.

[0029] Many specific details are set forth in the following description in order to provide a full understanding of the invention, but the invention may also be practiced in other ways different from those described herein; obviously, the embodiments in the specification are only some embodiments of the invention, and not all embodiments.

[0030] To further understand the present invention, preferred embodiments of the present invention are described below in conjunction with examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, and not for limiting the scope of the claims of the present invention.

[0031] In the following examples and comparative examples, the performance parameters of each raw material are as follows:

[0032] The silicon carbide whiskers are β-SiC whiskers with a diameter of 0.1 μm and a length of 10 μm;

[0033] The average particle size of titanium boride is 1 μm;

[0034] The average particle size of alumina is 1 μm;

[0035] The particle size of magnesium oxide is 1.5 μm;

[0036] Yttrium oxide has a particle size of 1.5 μm.

[0037] The carbon nanotubes have a diameter of 20 nm, a length of 5 μm, and a purity of 95%.

[0038] Unless otherwise specified, the other raw materials and conditions used in the following examples and comparative examples are all commercially available products and conventional conditions in the field.

[0039] Example 1

[0040] A method for forming a high-performance ceramic cutter head includes the following steps:

[0041] (1) Place 1g of single-walled carbon nanotubes in a mixture of 60ml of concentrated sulfuric acid and concentrated nitric acid (the volume ratio of concentrated sulfuric acid to concentrated nitric acid is 3:1), reflux at 80℃ for 4h in the dark to obtain acidified carbon nanotubes.

[0042] (2) Add acidified carbon nanotubes to a mixed solution of glucose and urea (the concentration of glucose in the mixed solution is 15wt%), control the mass ratio of acidified carbon nanotubes, glucose and urea to be 1:4:1, sonicate at 200W for 20min, place the resulting reaction solution in a reaction vessel, and react at 200℃ for 5h. After the reaction is completed, centrifuge the hydrothermal reaction solution at 5000rpm for 30min, and wash the centrifuged precipitate with anhydrous ethanol and deionized water in sequence and then dry to obtain the pre-coated carbon nanotube material.

[0043] (3) The above pre-coated carbon nanotube material is placed in a tube furnace and heated to 850°C for 1 hour under an argon atmosphere at a rate of 2°C / min to obtain the carbon nanotube material coated with the first coating.

[0044] (4) Mix 1g of the carbon nanotube material coated with the first coating with a 45wt% polycarbosilane solution at a mass ratio of 1:1, sonicate at 200W for 20min, then place in an oven and cure at 200℃ for 1h. After crushing and sieving, place in a tube furnace and heat to 1200℃ at a heating rate of 4℃ / min for 1h under an argon atmosphere to obtain nanocomposite powder.

[0045] (5) According to the stoichiometric ratio, 5g of nanocomposite powder, 3g of silicon carbide whiskers, 25g of titanium boride, 65g of alumina, 1g of sintering aid (magnesium oxide and yttrium oxide mixed in a mass ratio of 1:2) and anhydrous ethanol are placed in a ball mill jar with a solid-liquid ratio of 1:1. Zirconia is used as the ball milling medium, and the ball-to-material ratio is 10:1. The mixture is placed on a ball mill and ball milled at a speed of 100r / min for 24h. The slurry obtained from ball milling is dried at 60℃ and then passed through a 200-mesh sieve. The resulting powder is placed in a mold and heated at room temperature. The pre-pressed material was subjected to a pressure of 35 MPa for 15 min. The pre-pressed material was then placed in a hot-press sintering furnace under an argon atmosphere. The temperature was first increased to 7000℃ at a rate of 90℃ / min, then increased to 1000℃ / min at a rate of 85℃ / min, then increased to 1150℃ / min at a rate of 65℃ / min, and finally increased to 1575℃ at a rate of 40℃ / min. The temperature was held for 8 min. The pressure during the sintering process was 30 MPa, resulting in ceramic cutting tools.

[0046] Example 2

[0047] A method for forming a high-performance ceramic cutter head includes the following steps:

[0048] (1) Place 1.5g of single-walled carbon nanotubes in a mixture of 70ml of concentrated sulfuric acid and concentrated nitric acid (the volume ratio of concentrated sulfuric acid to concentrated nitric acid is 3:1), reflux at 80℃ for 5h in the dark to obtain acidified carbon nanotubes.

[0049] (2) Add acidified carbon nanotubes to a mixed solution of glucose and urea (the concentration of glucose in the mixed solution is 15wt%), control the mass ratio of acidified carbon nanotubes, glucose and urea to be 1:4.5:1, sonicate at 300W for 20min, place the resulting reaction solution in a reaction vessel, and react at 200℃ for 5.5h. After the reaction is completed, centrifuge the hydrothermal reaction solution at 6000rpm for 30min, and wash the centrifuged precipitate with anhydrous ethanol and deionized water in sequence and then dry to obtain the pre-coated carbon nanotube material.

[0050] (3) The above pre-coated carbon nanotube material is placed in a tube furnace and pyrolyzed at 850°C for 1 hour at a rate of 2.5°C / min under an argon atmosphere to obtain the carbon nanotube material coated with the first coating.

[0051] (4) Mix 1.5g of the carbon nanotube material coated with the first coating with a 50wt% polycarbosilane solution at a mass ratio of 1:1, sonicate at 300W for 20min, then place in an oven and cure at 200℃ for 1h, pulverize and sieve, then place in a tube furnace and heat to 1200℃ for 1h at a heating rate of 4.5℃ / min under an argon atmosphere to obtain nanocomposite powder;

[0052] (5) According to the stoichiometric ratio, 5.5g of nanocomposite powder, 4g of silicon carbide whiskers, 30g of titanium boride, 68g of alumina, 1.5g of sintering aid (magnesium oxide and yttrium oxide mixed in a mass ratio of 1:3) and anhydrous ethanol were placed in a ball mill jar with a solid-liquid ratio of 1:1. Zirconia was used as the ball milling medium with a ball-to-material ratio of 10:1. The mixture was placed on a ball mill and ball milled at a speed of 200 r / min for 24 h. The slurry obtained from the ball milling was dried at 70°C and then passed through a 200-mesh sieve. The resulting powder was placed in a mold and dried at room temperature. The pre-pressed material was subjected to a pressure of 38 MPa for 20 minutes. The pre-pressed material was then placed in a hot pressing sintering furnace under an argon atmosphere. The temperature was first increased to 700°C at a rate of 92°C / min, then increased to 1000°C / min at a rate of 86°C / min, then increased to 1150°C / min at a rate of 67°C / min, and finally increased to 1575°C at a rate of 41°C / min. The temperature was held for 7 minutes. The pressure during the hot pressing sintering process was 35 MPa, resulting in ceramic cutting tools.

[0053] Example 3

[0054] A method for forming a high-performance ceramic cutter head includes the following steps:

[0055] (1) Place 1g of single-walled carbon nanotubes in a mixture of 60ml of concentrated sulfuric acid and concentrated nitric acid (the volume ratio of concentrated sulfuric acid to concentrated nitric acid is 3:1), reflux at 80℃ for 4h in the dark to obtain acidified carbon nanotubes.

[0056] (2) Add acidified carbon nanotubes to a mixed solution of glucose and urea (the concentration of glucose in the mixed solution is 10wt%), control the mass ratio of acidified carbon nanotubes, glucose and urea to be 1:5:1, sonicate at 300W for 30min, place the resulting reaction solution in a reaction vessel, and react at 200℃ for 5.5h. After the reaction is completed, centrifuge the hydrothermal reaction solution at 6000rpm for 30min, and wash the centrifuged precipitate with anhydrous ethanol and deionized water in sequence and then dry to obtain the pre-coated carbon nanotube material.

[0057] (3) The above pre-coated carbon nanotube material is placed in a tube furnace and heated to 850°C for 1.5 h under an argon atmosphere to obtain the carbon nanotube material coated with the first coating.

[0058] (4) Mix 2g of the carbon nanotube material coated with the first coating with a 50wt% polycarbosilane solution at a mass ratio of 1:1, sonicate at 300W for 30min, then place in an oven and cure at 200℃ for 2h. After crushing and sieving, place in a tube furnace and heat to 1200℃ for 1h at a heating rate of 5℃ / min under an argon atmosphere to obtain nanocomposite powder.

[0059] (5) According to the stoichiometric ratio, 6g of nanocomposite powder, 3g of silicon carbide whiskers, 30g of titanium boride, 71g of alumina, 1.5g of sintering aid (magnesium oxide and yttrium oxide mixed in a mass ratio of 1:2) and anhydrous ethanol were placed in a ball mill jar with a solid-liquid ratio of 1:1. Zirconia was used as the ball milling medium with a ball-to-material ratio of 10:1. The mixture was placed on a ball mill and ball milled at a speed of 200 r / min for 24 h. The slurry obtained from the ball milling was dried at 80°C and then passed through a 200-mesh sieve. The resulting powder was placed in a mold and stored at room temperature. The pre-pressed material was subjected to a pressure of 35 MPa for 20 min. Finally, the pre-pressed material was placed in a hot pressing sintering furnace under an argon atmosphere. The temperature was first increased to 700℃ at a rate of 91℃ / min, then increased to 1000℃ / min at a rate of 87℃ / min, then increased to 1150℃ / min at a rate of 67℃ / min, and finally increased to 1575℃ at a rate of 42℃ / min. The temperature was held for 8 min. The pressure during the hot pressing sintering process was 32 MPa, resulting in ceramic cutting tools.

[0060] Example 4

[0061] A method for forming a high-performance ceramic cutter head includes the following steps:

[0062] (1) Place 2g of single-walled carbon nanotubes in a mixture of 80ml of concentrated sulfuric acid and concentrated nitric acid (the volume ratio of concentrated sulfuric acid to concentrated nitric acid is 3:1), reflux at 80℃ for 4h in the dark to obtain acidified carbon nanotubes.

[0063] (2) Add acidified carbon nanotubes to a mixed solution of glucose and urea (the concentration of glucose in the mixed solution is 15wt%), control the mass ratio of acidified carbon nanotubes, glucose and urea to be 1:4:1, sonicate at 300W for 20min, place the resulting reaction solution in a reaction vessel, and react at 200℃ for 5h. After the reaction is completed, centrifuge the hydrothermal reaction solution at 7000rpm for 30min, and wash the centrifuged precipitate with anhydrous ethanol and deionized water in sequence and then dry to obtain pre-coated carbon nanotube material.

[0064] (3) The above pre-coated carbon nanotube material is placed in a tube furnace and pyrolyzed at 850°C for 1 hour at a rate of 3°C / min under an argon atmosphere to obtain the carbon nanotube material coated with the first coating.

[0065] (4) Mix 1.6g of the carbon nanotube material coated with the first coating with a 50wt% polycarbosilane solution at a mass ratio of 1:1, sonicate at 300W for 30min, then place in an oven and cure at 200℃ for 1h, pulverize and sieve, then place in a tube furnace and heat to 1200℃ at a heating rate of 4℃ / min for 2h under an argon atmosphere to obtain nanocomposite powder;

[0066] (5) According to the stoichiometric ratio, 6g of nanocomposite powder, 4g of silicon carbide whiskers, 28g of titanium boride, 71g of alumina, 1.5g of sintering aid (magnesium oxide and yttrium oxide mixed in a mass ratio of 1:2) and anhydrous ethanol were placed in a ball mill jar with a solid-liquid ratio of 1:1. Zirconia was used as the ball milling medium with a ball-to-material ratio of 10:1. The mixture was placed on a ball mill and ball milled at a speed of 150r / min for 30h. The slurry obtained from the ball milling was dried at 75℃ and then passed through a 200-mesh sieve. The resulting powder was placed in a mold and heated at room temperature. The pre-pressed material was subjected to a pressure of 35 MPa for 20 min. Finally, the pre-pressed material was placed in a hot pressing sintering furnace under an argon atmosphere. The temperature was first increased to 700℃ at a rate of 95℃ / min, then increased to 1000℃ / min at a rate of 85℃ / min, then increased to 1150℃ / min at a rate of 65℃ / min, and finally increased to 1575℃ at a rate of 43℃ / min. The temperature was held for 7 min. The pressure during the hot pressing sintering process was 36 MPa, resulting in ceramic cutting tools.

[0067] Example 5

[0068] A method for forming a high-performance ceramic cutter head includes the following steps:

[0069] (1) Place 1.5g of single-walled carbon nanotubes in a mixture of 60ml of concentrated sulfuric acid and concentrated nitric acid (volume ratio of concentrated sulfuric acid to concentrated nitric acid is 3:1), reflux at 80℃ for 4h in the dark to obtain acidified carbon nanotubes.

[0070] (2) Add acidified carbon nanotubes to a mixed solution of glucose and urea (the concentration of glucose in the mixed solution is 15wt%), control the mass ratio of acidified carbon nanotubes, glucose and urea to be 1:5:1, sonicate at 300W for 30min, place the resulting reaction solution in a reaction vessel, and react at 200℃ for 6h. After the reaction is completed, centrifuge the hydrothermal reaction solution at 7000rpm for 30min, and wash the centrifuged precipitate with anhydrous ethanol and deionized water in sequence and then dry to obtain the pre-coated carbon nanotube material.

[0071] (3) The above pre-coated carbon nanotube material is placed in a tube furnace and heated to 850°C for 1 hour under an argon atmosphere at a rate of 2°C / min to obtain the carbon nanotube material coated with the first coating.

[0072] (4) Mix 1.5g of the carbon nanotube material coated with the first coating with a 50wt% polycarbosilane solution at a mass ratio of 1:1, sonicate at 250W for 30min, then place in an oven and cure at 200℃ for 1h, pulverize and sieve, then place in a tube furnace and heat to 1200℃ at a heating rate of 4℃ / min for 1h under an argon atmosphere to obtain nanocomposite powder;

[0073] (5) According to the stoichiometric ratio, 5.5g of nanocomposite powder, 4g of silicon carbide whiskers, 27g of titanium boride, 68g of alumina, 1.6g of sintering aid (magnesium oxide and yttrium oxide mixed in a mass ratio of 1:2) and anhydrous ethanol were placed in a ball mill jar with a solid-liquid ratio of 1:1. Zirconia was used as the ball milling medium with a ball-to-material ratio of 10:1. The mixture was placed on a ball mill and ball milled at a speed of 200r / min for 30h. The slurry obtained from the ball milling was dried at 80℃ and then passed through a 200-mesh sieve. The resulting powder was placed in a mold and dried at room temperature. The pre-pressed material was subjected to a pressure of 40 MPa for 15 minutes. The pre-pressed material was then placed in a hot pressing sintering furnace under an argon atmosphere. The temperature was first increased to 700℃ at a rate of 90℃ / min, then increased to 1000℃ / min at a rate of 86℃ / min, then increased to 1150℃ / min at a rate of 67℃ / min, and finally increased to 1575℃ at a rate of 42℃ / min. The temperature was held for 8 minutes. The pressure during the hot pressing sintering process was 35 MPa, resulting in ceramic cutting tools.

[0074] Comparative Example 1

[0075] The difference between this comparative example and Example 5 is that no nanocomposite powder is added, but the other operations are the same as in Example 5.

[0076] Comparative Example 2

[0077] The difference between this comparative example and Example 5 is that no silicon carbide whiskers are added; all other operations are the same as in Example 5.

[0078] Comparative Example 3

[0079] The difference between this comparative example and Example 5 is that an equal amount of single-walled carbon nanotubes are used to replace the nanocomposite powder in Example 5, while other operations are the same as in Example 5.

[0080] Comparative Example 4

[0081] The difference between this comparative example and Example 5 is that in step (2), an equal amount of glucose is used to replace urea, while the other operations are the same as in Example 5.

[0082] Comparative Example 5

[0083] The difference between this comparative example and Example 5 is that in step (2), an equal amount of urea is used to replace glucose, while the other operations are the same as in Example 5.

[0084] Comparative Example 6

[0085] The difference between this comparative example and Example 5 is that step (3) is not included, while the other operations are the same as in Example 5.

[0086] Comparative Example 7

[0087] The difference between this comparative example and Example 5 is that steps (2) and (3) are not included, while other operations are the same as in Example 5.

[0088] Comparative Example 8

[0089] The difference between this comparative example and Example 5 is that step (4) is not included; the other operations are the same as in Example 5.

[0090] Comparative Example 9

[0091] The difference between this comparative example and Example 5 is that in step (3), the heating rate is 5℃ / min, and the other operations are the same as in Example 5.

[0092] Comparative Example 10

[0093] The difference between this comparative example and Example 5 is that in step (4), the mass ratio of the carbon nanotube material coated by the first coating to the polycarbosilane solution with a concentration of 45-50wt% is 1:2, and the other operations are the same as in Example 5.

[0094] Comparative Example 11

[0095] The difference between this comparative example and Example 5 is that in step (4), the heating rate is 8°C / min, and the other operations are the same as in Example 5.

[0096] Comparative Example 12

[0097] The difference between this comparative example and Example 5 is that in step (4), the amount of nanocomposite powder added is 9g, and the other operations are the same as in Example 5.

[0098] Comparative Example 13

[0099] The difference between this comparative example and Example 5 is that in step (4), the amount of silicon carbide whiskers added is 8g, and the other operations are the same as in Example 5.

[0100] Comparative Example 14

[0101] The difference between this comparative example and Example 5 is that in step (5), the temperature is directly increased to 1575°C at a rate of 90°C / min during hot pressing and sintering, while the other operations are the same as in Example 5.

[0102] The performance of the ceramic cutting tools prepared in the above embodiments and comparative examples was tested below. The test methods and results are as follows:

[0103] The ceramic cutting tool samples in the above embodiments and comparative examples were cut into strips of 3.5mm × 4.2mm × 30mm using a CNC wire EDM machine. The sample strips were then rough-ground and fine-ground using a universal tool grinder. The finely ground sample strips were then ground with W5 grit diamond polishing paste and finally polished with diamond spray polishing agent (W2.5 grit) on a polishing machine to obtain ceramic sample strips (3mm × 4mm × 30mm). The sample strips were then chamfered to eliminate experimental errors caused by stress concentration.

[0104] Mechanical property testing:

[0105] 1. Bending strength

[0106] A ceramic specimen with standard dimensions of 3mm × 4mm × 30mm was subjected to a three-point bending fracture test using an electronic universal testing machine (AGS-X5KN, Japan) at a crosshead speed of 0.5mm / min. The critical load P at which the ceramic specimen fractured was determined. The formula for calculating the bending strength of the ceramic specimen is shown below:

[0107] Bending strength = 3PL / 2bh 2 ;

[0108] Where P is the critical load (N) at which the ceramic specimen breaks, b and h are the width and height (mm) of the ceramic specimen, respectively, and the fixed span L = 20mm.

[0109] 2. Vickers hardness and fracture toughness

[0110] A Vickers indentation was pre-formed on the polished surface of a ceramic specimen using a Vickers hardness tester (HV-120, China). The diagonal length 2a (mm) of the Vickers indentation and the indentation crack length c (mm) were measured. The test load was 196 N, and the holding time was 15 s. The Vickers hardness Hv (GPa) and fracture toughness K were measured. IC (MPa·m 1 / 2 The calculation formula for ) is as follows:

[0111] Hv=1.8544P / (2a) 2 ;K IC =0.203Hva 1 / 2 (c / a) 3 / 2 ;

[0112] The test results are shown in Table 1.

[0113] Table 1

[0114]

[0115]

[0116] As can be seen from the test results in Table 1, compared with the comparative example, the present invention incorporates silicon carbide whiskers and nanocomposite powders into the ceramic matrix for synergistic modification, which effectively improves the performance of ceramic cutting tools.

[0117] The nanocomposite powder of the present invention uses single-walled carbon nanotubes as a matrix. First, a carbon-nitrogen coating layer is constructed on its surface. Then, under certain conditions, the pre-coating layer is transformed into a high-temperature resistant hard coating. Finally, polycarbosilane is used as a raw material, which is pyrolyzed under certain conditions to form a continuous silicon carbide layer. The resulting nanocomposite powder has good compatibility with silicon carbide whiskers and ceramic matrix, thus improving the performance of the material.

[0118] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of these embodiments are merely to aid in understanding the method and core ideas of the present invention, including the best mode, and to enable any person skilled in the art to practice the present invention, including manufacturing and using any device or system, and implementing any combined method. It should be noted that those skilled in the art can make various improvements and modifications to the present invention without departing from its principles, and these improvements and modifications also fall within the scope of protection of the claims. The scope of protection of this patent is defined by the claims and may include other embodiments that can be conceived by those skilled in the art. If these other embodiments have structural elements similar to those expressed in the claims, or if they include equivalent structural elements that are not substantially different from those expressed in the claims, then these other embodiments should also be included within the scope of the claims.

Claims

1. A high-performance ceramic cutter disc, characterized in that, By weight, it includes 5-7 parts of nanocomposite powder, 3-6 parts of silicon carbide whiskers, 25-35 parts of titanium boride, 65-75 parts of alumina, and 1-2 parts of sintering aid. The matrix of the nanocomposite powder is carbon nanotubes, and the surface of the carbon nanotube matrix is ​​sequentially modified with a first coating and a second coating. The first coating is a carbon nitride coating, and the second coating is an in-situ grown silicon carbide layer. Its preparation method includes the following steps: (1) Carbon nanotubes are acidified to obtain acidified carbon nanotubes. Then, the acidified carbon nanotubes are added to a mixed solution of glucose and urea and ultrasonically treated at 200-300W for 20-30 minutes. The resulting reaction solution is placed in a reaction vessel for hydrothermal reaction. After the reaction is completed, the hydrothermal reaction solution is centrifuged, the centrifuged precipitate is washed and dried to obtain pre-coated carbon nanotube material. (2) The pre-coated carbon nanotube material is placed in a tube furnace and subjected to pyrolysis reaction to obtain carbon nanotube material coated with the first coating; the atmosphere of the pyrolysis reaction is an inert gas, the heating rate is 2-3℃ / min, the temperature is 800-900℃, and the time is 1-2h. (3) The carbon nanotube material coated with the first coating above is mixed with polycarbosilane solution, ultrasonically treated at 200-300W for 20-30 minutes, then cured, crushed and sieved and placed in a tube furnace for heat treatment to obtain nanocomposite powder. (4) According to the stoichiometric ratio, nanocomposite powder, silicon carbide whiskers, titanium boride, alumina, sintering aid and anhydrous ethanol are placed in a ball mill jar, and zirconium oxide is used as the ball milling medium for ball milling. The slurry obtained by ball milling is dried and sieved. The powder obtained is placed in a mold for pre-pressing treatment. Finally, the pre-pressed blank is hot-pressed and sintered to obtain a ceramic cutter disc.

2. The high-performance ceramic cutter head according to claim 1, characterized in that, The sintering aid is a mixture of magnesium oxide and yttrium oxide, wherein the mass ratio of magnesium oxide to yttrium oxide is 1:(2-3).

3. The high-performance ceramic cutter head according to claim 2, characterized in that, The silicon carbide whiskers are β-SiC whiskers with a diameter of 0.1-0.2 μm and a length of 10-20 μm. The titanium boride has an average particle size of 1-2 μm, the aluminum oxide has an average particle size of 1-2 μm, the magnesium oxide has a particle size of 1.5-2.5 μm, and the yttrium oxide has a particle size of 1.5-2.5 μm.

4. The high-performance ceramic cutter head according to claim 1, characterized in that, In step (1), the acid solution for acidification is a mixture of concentrated sulfuric acid and concentrated nitric acid, with a volume ratio of 3:

1. The acidification conditions are reflux at 80°C for 3-6 hours.

5. A high-performance ceramic cutter head according to claim 1, characterized in that, In step (1), the concentration of glucose in the mixed solution is 1-20wt%, and the mass ratio of acidified carbon nanotubes, glucose and urea is 1:(4-5):1; the hydrothermal reaction temperature is 180-200℃ and the time is 5-6h.

6. A high-performance ceramic cutter head according to claim 1, characterized in that, In step (3), the concentration of the polycarbosilane solution is 45-50 wt%, and the mass ratio of the carbon nanotube material coated by the first coating to the polycarbosilane solution is 1:1; the curing temperature is 200℃ and the time is 1-2 h; the heat treatment temperature is 1200℃, the heating rate is 4-5℃ / min, and the time is 1-2 h.

7. A high-performance ceramic cutter head according to claim 1, characterized in that, In step (4), the ball-to-material ratio during ball milling is (10-20):1, the rotation speed of the ball mill during ball milling is 100-200 r / min, and the ball milling time is 20-30 h; the temperature of the pre-pressing treatment is room temperature, the pressure is 35-40 MPa, and the pressing time is 15-20 min.

8. A high-performance ceramic cutter head according to claim 1, characterized in that, In step (4), the hot pressing sintering conditions are as follows: first, the temperature is raised to 700-800℃ at a rate of 90-95℃ / min, then raised to 1000-1050℃ at a rate of 85-88℃ / min, then raised to 1150-1200℃ at a rate of 65-70℃ / min, and finally raised to 1550-1580℃ at a rate of 40-43℃ / min, and held for 5-10 min; the pressure for hot pressing sintering is 30-40 MPa.

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