High-performance ceramic cutter head and forming method thereof

Abstract

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

Description

Technical Field

[0001] The present invention relates to the technical field of tool preparation, and particularly relates to a high-performance ceramic cutter head and a forming method thereof. Background Art

[0002] The ceramic cutter head is one of the core components of a coffee grinder, mainly used for grinding coffee beans into uniform particles. The ceramic cutter head usually consists of two circular grinding discs: the fixed disc is installed at the bottom of the coffee grinder and remains stationary; the rotating disc is connected to the motor or manual axis and rotates at a high speed to cut the coffee beans.

[0003] Currently, most ceramic cutter heads use zirconia ceramics, which have the following advantages: 1. High hardness and good wear resistance; 2. Low thermal conductivity, which can effectively reduce the heat accumulation during grinding, thereby protecting the coffee flavor; 3. Resistant to acid and alkali corrosion, not easy to rust, and does not adsorb coffee oil, avoiding odor residue. However, zirconia ceramic cutter heads also have many disadvantages, such as: high brittleness, easy to break under external force impact, and difficult to meet the high-speed processing of difficult-to-machine materials. Therefore, it is of great significance to provide a new ceramic cutter head material. 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 head, which not only has high hardness but also excellent mechanical properties.

[0005] Another technical problem to be solved by the present invention is to provide a forming method of a high-performance ceramic cutter head, which is simple to operate, and the ceramic cutter obtained by optimizing the preparation process conditions has excellent comprehensive performance.

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

[0007] A high-performance ceramic cutter head, in parts by weight, comprises 5-7 parts of nano-composite 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 nano-composite powder is carbon nanotubes, and the surface of the carbon nanotube matrix is successively modified with a first coating and a second coating. The first coating is a carbonitride 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, and 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 average particle size of titanium boride is 1-2 μm, the average particle size of alumina is 1-2 μm, the particle size of magnesium oxide is 1.5-2.5 μm, and the particle size of yttrium oxide is 1.5-2.5 μm.

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

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

[0013] (1) Acidify carbon nanotubes to obtain acidified carbon nanotubes, then add the acidified carbon nanotubes to a mixed solution of glucose and urea, perform ultrasonic treatment, place the obtained reaction solution in a reaction kettle for hydrothermal reaction, after the reaction ends, centrifuge the hydrothermal reaction solution, wash the centrifuged precipitate and dry it to obtain a pre-coated carbon nanotube material;

[0014] (2) Place the pre-coated carbon nanotube material in a tubular furnace for pyrolysis reaction to obtain a carbon nanotube material coated with a first coating;

[0015] (3) Mix the above carbon nanotube material coated with a first coating with a polycarbosilane solution, perform ultrasonic treatment, then perform curing treatment, crush and screen it, and place it in a tubular furnace for heat treatment to obtain a nano-composite powder;

[0016] (4) According to the metering ratio, place the nano-composite powder, silicon carbide whiskers, titanium boride, alumina, sintering aid, and absolute ethanol in a ball mill tank, use zirconia as the ball milling medium for ball milling treatment, dry the ball-milled slurry and pass it through a sieve, place the obtained powder in a mold for pre-pressing treatment, and finally perform hot-pressing sintering on the green body obtained by the pre-pressing treatment to obtain a ceramic tool.

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

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

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

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

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

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

[0023] Preferably, in step (4), the conditions for hot press sintering are as follows: first, heat up to 700-800 °C at a rate of 90-95 °C / min, then heat up to 1000-1050 °C / min at a rate of 85-88 °C / min, then heat up to 1150-1200 °C / min at a rate of 65-70 °C / min, and finally heat up to 1550-1580 °C at a rate of 40-43 °C / min, keep warm for 5-10 min, and the pressure for hot press sintering and forming is 30-40 MPa.

[0024] Due to the adoption of the above technical solutions, the present invention has at least the following beneficial effects:

[0025] 1. The present invention adds nano-composite powder to modify the ceramic matrix. The nano-composite powder takes carbon nanotubes as the matrix. First, through hydrothermal and pyrolysis, a carbonitride coating is formed on the surface of the carbon nanotubes as the first coating, which improves the chemical stability and interfacial bonding force of the carbon nanotubes. Moreover, the high-temperature stability of the above coating reduces the structural degradation of the carbon nanotubes during the subsequent sintering process. Secondly, the present invention also uses polycarbosilane as the raw material to in-situ crack and generate a SiC coating on the surface of the first coating as the second coating, further improving the interfacial bonding property between the nano-composite powder and the ceramic matrix, reducing the interfacial stress, and at the same time improving the load transfer efficiency between the nano-composite powder and the matrix, and improving the strength and toughness of the ceramic tool.

[0026] 2. The present invention adds a certain amount of silicon carbide whiskers to the ceramic matrix to synergistically modify the ceramic matrix with the nano-composite powder. The silicon carbide whiskers with a high aspect ratio can effectively hinder the crack propagation through the crack deflection and bridging mechanisms, significantly improving the fracture toughness of the ceramic tool. It forms a three-dimensional network with the nano-composite powder to jointly bear the external stress, reducing the local stress concentration in the matrix and improving the performance of the ceramic tool.

[0027] 3. When preparing ceramic cutting tools by hot pressing sintering in the present invention, a staged heating method is adopted. First, the temperature is rapidly increased to a certain temperature, and the residual solvent is rapidly evaporated at high temperature and the low-melting-point organic matter is decomposed, so as to avoid the formation of pores due to the carbonization of organic matter in the subsequent high-temperature stage. Moreover, during the rapid heating process, preliminary diffusion begins to occur on the surfaces of alumina and titanium boride particles, forming local neck connections, providing a framework support for subsequent densification; Secondly, during the medium-speed heating process, the sintering aids magnesium oxide and yttrium oxide form a eutectic liquid phase, wetting the particle surfaces, reducing the interfacial energy, and promoting particle sliding and rearrangement. The reduction in the heating rate during this process alleviates the local thermal stress caused by rapid heating, prevents the generation of microcracks, and at the same time the liquid phase fills the pores, improving the density of the material; Then, the heating rate continues to decrease, thereby prolonging the existence time of the liquid phase. A continuous liquid-phase network is formed in the magnesium oxide-yttrium oxide-aluminum oxide system, and the grain boundary migration is accelerated through the dissolution-precipitation mechanism, eliminating closed pores. The silicon carbide whiskers and the nano-composite powder are directionally distributed in the above-mentioned liquid phase, forming a strong interfacial bond with the ceramic matrix and inhibiting abnormal grain growth; Finally, the heating rate is continuously decreased to raise the temperature of hot pressing sintering to a certain temperature, and the residual pores are completely eliminated through the plastic flow and creep mechanisms, improving the density of the material. Moreover, the holding time is effectively optimized, restricting the grain growth time, avoiding excessive coarsening of alumina and titanium boride grains, maintaining the dispersion strengthening effect of the nano-composite powder, and at the same time retaining the toughening effect of the silicon carbide whiskers. Specific embodiments

[0028] In order to more clearly understand the above-mentioned objects, features and advantages of the present invention, the solutions of the present invention will be further described below. It should be noted that, without conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other.

[0029] Many specific details are set forth in the following description in order to fully understand the present invention, but the present invention can also be implemented in other ways different from those described herein; Obviously, the embodiments in the specification are only a part of the embodiments of the present invention, rather than all the embodiments.

[0030] In order to further understand the present invention, the preferred embodiments of the present invention will be described below in conjunction with embodiments, but it should be understood that these descriptions are only for further explaining the features and advantages of the present invention, rather than limiting 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 magnesia is 1.5 μm;

[0036] The particle size of yttrium oxide is 1.5 μm

[0037] The diameter of the carbon nanotubes is 20 nm; the length is 5 μm; the purity is 95%.

[0038] In the following examples and comparative examples, other raw materials and the conditions are commercially available products and conventional conditions in the art unless otherwise specified.

[0039] Example 1

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

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

[0042] (2) Add the acidified carbon nanotubes to a mixed solution of 50 ml of glucose and urea (the concentration of glucose in the mixed solution is 15 wt%), control the mass ratio of acidified carbon nanotubes, glucose, and urea to be 1:4:1, ultrasonically treat at 200 W for 20 min, place the obtained reaction solution in a reaction kettle, react at 200 °C for 5 h, after the reaction is completed, centrifuge the hydrothermal reaction solution at a centrifugal speed of 5000 rpm for 30 min, wash the centrifugal precipitate successively with absolute ethanol and deionized water and then dry to obtain a pre-coated carbon nanotube material;

[0043] (3) Place the above pre-coated carbon nanotube material in a tubular furnace, under an argon atmosphere, heat it to 850 °C at a rate of 2 °C / min for pyrolysis treatment for 1 h to obtain a carbon nanotube material coated with a first coating;

[0044] (4) Mix 1 g of the above carbon nanotube material coated with a first coating with a 45 wt% polycarbosilane solution at a mass ratio of 1:1, ultrasonically treat at 200 W for 20 min, then place it in an oven, cure it at 200 °C for 1 h, crush and screen it, then place it in a tubular furnace, under an argon atmosphere, heat it to 1200 °C at a heating rate of 4 °C / min for treatment for 1 h to obtain a nano-composite powder;

[0045] (5) According to the metering ratio, 5 g of nano-composite powder, 3 g of silicon carbide whiskers, 25 g of titanium boride, 65 g of alumina, 1 g of sintering aid (magnesium oxide and yttrium oxide are mixed in a mass ratio of 1:2), and anhydrous ethanol are placed in a ball milling tank. The solid-liquid ratio is 1:1. Using zirconia as the ball milling medium and the ball-to-material ratio is 10:1, it is placed on a ball mill and ball milled for 24 h at a ball milling speed of 100 r / min. The slurry obtained by ball milling is dried at 60 °C and then sieved through a 200-mesh sieve. The obtained powder is placed in a mold and pre-pressed for 15 min at room temperature and a pressure of 35 MPa. Finally, the green body obtained by pre-pressing is placed in a hot press sintering furnace. Under an argon atmosphere, it is first heated to 700 °C at a rate of 90 °C / min, then heated to 1000 °C / min at a rate of 85 °C / min, then heated to 1150 °C / min at a rate of 65 °C / min, and finally heated to 1575 °C at a rate of 40 °C / min and held for 8 min. The pressure during the sintering process is 30 MPa to obtain a ceramic tool.

[0046] Example 2

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

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

[0049] (2) Add the acidified carbon nanotubes to a mixed solution of 50 ml of glucose and urea (the concentration of glucose in the mixed solution is 15 wt%). Control the mass ratio of acidified carbon nanotubes, glucose, and urea to be 1:4.5:1, and ultrasonically treat for 20 min at 300 W. The obtained reaction solution is placed in a reaction kettle and reacted at 200 °C for 5.5 h. After the reaction, the hydrothermal reaction solution is centrifuged at a centrifugal speed of 6000 rpm for 30 min. The centrifugal precipitate is washed successively with anhydrous ethanol and deionized water and then dried to obtain a pre-coated carbon nanotube material;

[0050] (3) Place the above pre-coated carbon nanotube material in a tubular furnace. Under an argon atmosphere, heat it to 850 °C at a rate of 2.5 °C / min for pyrolysis treatment for 1 h to obtain a carbon nanotube material coated with a first coating;

[0051] (4) Mix 1.5 g of the above carbon nanotube material coated with the first coating with a 50 wt% polycarbosilane solution in a mass ratio of 1:1, ultrasonically treat for 20 min at 300 W, then place it in an oven and cure it at 200 °C for 1 h. After crushing and screening, place it in a tubular furnace. Under an argon atmosphere, heat it to 1200 °C at a heating rate of 4.5 °C / min and treat for 1 h to obtain a nano-composite powder;

[0052] (5) According to the metering ratio, 5.5 g of nano-composite powder, 4 g of silicon carbide whiskers, 30 g of titanium boride, 68 g of alumina, 1.5 g of sintering aids (magnesium oxide and yttrium oxide are mixed in a mass ratio of 1:3) and absolute ethanol are placed in a ball milling tank. The solid-liquid ratio is 1:1. Using zirconia as the ball milling medium and the ball-to-material ratio is 10:1. It is placed on a ball mill and ball milled for 24 h at a ball milling speed of 200 r / min. The slurry obtained by ball milling is dried at 70 °C and then passed through a 200-mesh sieve. The obtained powder is placed in a mold and pre-pressed for 20 min at room temperature and a pressure of 38 MPa. Finally, the green body obtained by pre-pressing is placed in a hot press sintering furnace. Under an argon atmosphere, first heat it to 700 °C at a rate of 92 °C / min, then heat it to 1000 °C / min at a rate of 86 °C / min, and then heat it to 1150 °C / min at a rate of 67 °C / min. Finally, heat it to 1575 °C at a rate of 41 °C / min and hold for 7 min. The pressure during the hot press sintering process is 35 MPa to obtain a ceramic tool.

[0053] Example 3

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

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

[0056] (2) Add the acidified carbon nanotubes to a mixed solution of 50 ml of glucose and urea (the concentration of glucose in the mixed solution is 10 wt%). Control the mass ratio of acidified carbon nanotubes, glucose, and urea to be 1:5:1. Ultrasonically treat it at 300 W for 30 min. The obtained reaction solution is placed in a reaction kettle and reacted at 200 °C for 5.5 h. After the reaction, the hydrothermal reaction solution is centrifuged at a centrifugal speed of 6000 rpm for 30 min. The centrifugal precipitate is washed successively with absolute ethanol and deionized water and then dried to obtain a pre-coated carbon nanotube material;

[0057] (3) Place the above pre-coated carbon nanotube material in a tube furnace. Under an argon atmosphere, heat it to 850 °C at a rate of 3 °C / min for pyrolysis treatment for 1.5 h to obtain a carbon nanotube material coated with a first coating;

[0058] (4) Mix 2 g of the above carbon nanotube material coated with the first coating with a 50 wt% polycarbosilane solution at a mass ratio of 1:1, ultrasonically treat it at 300 W for 30 min, then place it in an oven, cure it at 200 °C for 2 h, crush and screen it, and then place it in a tubular furnace. Under an argon atmosphere, heat it to 1200 °C at a heating rate of 5 °C / min and treat it for 1 h to obtain a nano-composite powder;

[0059] (5) According to the metering ratio, put 6 g of nano-composite powder, 3 g of silicon carbide whiskers, 30 g of titanium boride, 71 g of alumina, 1.5 g of sintering aids (magnesium oxide and yttrium oxide are mixed in a mass ratio of 1:2), and anhydrous ethanol into a ball milling tank. The solid-liquid ratio is 1:1. Using zirconia as the ball milling medium and the ball-to-material ratio is 10:1. Place it on a ball mill and ball mill it at a ball milling speed of 200 r / min for 24 h. The slurry obtained by ball milling is dried at 80 °C and then screened through a 200-mesh sieve. The obtained powder is placed in a mold and pre-pressed at room temperature and a pressure of 35 MPa for 20 min. Finally, the green body obtained by pre-pressing is placed in a hot press sintering furnace. Under an argon atmosphere, first heat it to 700 °C at a rate of 91 °C / min, then heat it to 1000 °C / min at a rate of 87 °C / min, and then heat it to 1150 °C / min at a rate of 67 °C / min. Finally, heat it to 1575 °C at a rate of 42 °C / min, hold it for 8 min, and the pressure during the hot press sintering process is 32 MPa to obtain a ceramic cutting tool.

[0060] Example 4

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

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

[0063] (2) Add the acidified carbon nanotubes to a mixed solution of 50 ml of glucose and urea (the concentration of glucose in the mixed solution is 15 wt%). Control the mass ratio of acidified carbon nanotubes, glucose, and urea to be 1:4:1. Ultrasonically treat it at 300 W for 20 min. Place the obtained reaction solution in a reaction kettle and react at 200 °C for 5 h. After the reaction, centrifuge the hydrothermal reaction solution at a centrifugal speed of 7000 rpm for 30 min. Wash the centrifugal precipitate with anhydrous ethanol and deionized water in turn and then dry it to obtain a pre-coated carbon nanotube material;

[0064] (3) Place the above pre-coated carbon nanotube material in a tubular furnace. Under an argon atmosphere, heat it to 850 °C at a rate of 3 °C / min and pyrolyze it for 1 h to obtain a carbon nanotube material coated with the first coating;

[0065] (4) Mix 1.6 g of the above-mentioned carbon nanotube material coated with the first coating with a 50 wt% polycarbosilane solution at a mass ratio of 1:1, ultrasonically treat it for 30 min at 300 W, then place it in an oven, cure it at 200 °C for 1 h, crush and screen it, and then place it in a tube furnace. Under an argon atmosphere, heat it to 1200 °C at a heating rate of 4 °C / min and treat it for 2 h to obtain a nano-composite powder;

[0066] (5) According to the metering ratio, put 6 g of nano-composite powder, 4 g of silicon carbide whiskers, 28 g of titanium boride, 71 g of alumina, 1.5 g of sintering aids (magnesium oxide and yttrium oxide are mixed in a mass ratio of 1:2) and anhydrous ethanol into a ball milling tank, with a solid-liquid ratio of 1:1. Using zirconia as the ball milling medium and a ball-to-material ratio of 10:1, place it on a ball mill and ball mill it for 30 h at a ball milling speed of 150 r / min. The slurry obtained by ball milling is dried at 75 °C and then sieved through a 200-mesh sieve. The obtained powder is placed in a mold and pre-pressed at room temperature and a pressure of 35 MPa for 20 min. Finally, the green body obtained by pre-pressing is placed in a hot press sintering furnace. Under an argon atmosphere, first heat it to 700 °C at a rate of 95 °C / min, then heat it to 1000 °C / min at a rate of 85 °C / min, then heat it to 1150 °C / min at a rate of 65 °C / min, and finally heat it to 1575 °C at a rate of 43 °C / min, hold for 7 min, and the pressure during the hot press sintering process is 36 MPa to obtain a ceramic cutting tool.

[0067] Example 5

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

[0069] (1) Place 1.5 g of single-walled carbon nanotubes in a mixture of 60 ml 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 °C in the dark for 4 h to obtain acidified carbon nanotubes;

[0070] (2) Add the acidified carbon nanotubes to a mixed solution of 50 ml of glucose and urea (the concentration of glucose in the mixed solution is 15 wt%), control the mass ratio of acidified carbon nanotubes, glucose, and urea to be 1:5:1, ultrasonically treat it for 30 min at 300 W, place the obtained reaction solution in a reaction kettle, react at 200 °C for 6 h, after the reaction, centrifuge the hydrothermal reaction solution at a centrifugal speed of 7000 rpm for 30 min, wash the centrifugal precipitate with anhydrous ethanol and deionized water in sequence and then dry it to obtain a pre-coated carbon nanotube material;

[0071] (3) Place the above-mentioned pre-coated carbon nanotube material in a tube furnace, under an argon atmosphere, heat it to 850 °C at a rate of 2 °C / min for pyrolysis treatment for 1 h to obtain a carbon nanotube material coated with the first coating;

[0072] (4) Mix 1.5 g of the above-mentioned carbon nanotube material coated with the first coating with a 50 wt% polycarbosilane solution at a mass ratio of 1:1, ultrasonically treat it for 30 min at 250 W, then place it in an oven, cure it at 200 °C for 1 h, crush and screen it, and then place it in a tube furnace. Under an argon atmosphere, heat it to 1200 °C at a heating rate of 4 °C / min and treat it for 1 h to obtain a nano-composite powder;

[0073] (5) According to the metering ratio, put 5.5 g of nano-composite powder, 4 g of silicon carbide whiskers, 27 g of titanium boride, 68 g of alumina, 1.6 g of sintering aids (magnesium oxide and yttrium oxide are mixed in a mass ratio of 1:2) and anhydrous ethanol into a ball milling tank. The solid-liquid ratio is 1:1. Using zirconia as the ball milling medium and the ball-to-material ratio is 10:1. Place it on a ball mill and ball mill it for 30 h at a ball milling speed of 200 r / min. The slurry obtained by ball milling is dried at 80 °C and then screened through a 200-mesh sieve. The obtained powder is placed in a mold and pre-pressed at room temperature and a pressure of 40 MPa for 15 min. Finally, the green body obtained by pre-pressing is placed in a hot press sintering furnace. Under an argon atmosphere, first heat it to 700 °C at a rate of 90 °C / min, then heat it to 1000 °C / min at a rate of 86 °C / min, then heat it to 1150 °C / min at a rate of 67 °C / min, and finally heat it to 1575 °C at a rate of 42 °C / min and hold it for 8 min. The pressure during the hot press sintering process is 35 MPa to obtain a ceramic cutting tool.

[0074] Comparative Example 1

[0075] The difference between this comparative example and Example 5 is that no nano-composite powder is added, and other operations are the same as those 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, and other operations are the same as those 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 is used to replace the nano-composite powder in Example 5, and other operations are the same as those 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, and other operations are the same as those 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, and 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 it does not include step (3), and 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 it does not include steps (2) and (3), and 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 it does not include step (4), and 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°C / min, and 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 with the first coating to the polycarbosilane solution with a concentration of 45 - 50 wt% is 1:2, and 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 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 addition amount of the nano - composite powder is 9 g, and 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 addition amount of silicon carbide whiskers is 8 g, and 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), during hot - press sintering, the temperature is directly raised to 1575°C at a rate of 90°C / min, and other operations are the same as in Example 5.

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

[0103] The ceramic cutting tool samples in the above-mentioned examples and comparative examples were cut into strip samples of 3.5 mm × 4.2 mm × 30 mm using a CNC wire electrical discharge machining machine. The sample strips were rough-ground and finish-ground using a universal tool grinder. The polished sample strips were ground using diamond grinding paste with a particle size of W5, and finally polished using a diamond spray polishing agent (W2.5 particle size) on a polishing machine to obtain ceramic sample strips (3 mm × 4 mm × 30 mm), and chamfered to eliminate experimental errors caused by stress concentration.

[0104] Mechanical property test:

[0105] 1. Flexural strength

[0106] Using an electronic universal testing machine (AGS-X5KN, Japan), a fracture test was carried out on a ceramic sample strip with standard dimensions of 3 mm × 4 mm × 30 mm based on the three-point bending method at a crosshead speed of 0.5 mm / min displacement rate to measure the critical load P when the ceramic sample strip fractured. The calculation formula for the flexural strength of the ceramic sample strip is as follows:

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

[0108] where P is the critical load (N) when the ceramic sample strip fractures, b and h are the width and height (mm) of the ceramic sample strip respectively, and the fixed span L = 20 mm.

[0109] 2. Vickers hardness and fracture toughness

[0110] Using a Vickers hardness tester (HV-120 type, China), Vickers indentations were prefabricated on the polished surface of the ceramic sample strip, and the diagonal length 2a (mm) and indentation crack length c (mm) of the Vickers indentation were measured. The test load was 196 N, and the holding time was 15 s. The calculation formulas for Vickers hardness Hv (GPa) and fracture toughness K IC (MPa·m 1 / 2 ) are 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 tests in Table 1, compared with the comparative example, silicon carbide whiskers and nano-composite powder are added to the ceramic matrix in the present invention for synergistic modification, effectively improving the performance of the ceramic tool.

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

[0118] Specific examples are used in this article to elaborate on the principle and implementation mode of the present invention. The description of the above embodiments is only used to help understand the method and its core idea of the present invention, including the best mode, and also enables 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 for those of ordinary skill in the art in the technical field, without departing from the principle of the present invention, several improvements and modifications can be made to the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention. The protection scope of the present invention 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 approximately the same as the literal description of the claims, or if they include equivalent structural elements that have no substantial difference from the literal description of the claims, then these other embodiments should also be included within the scope of the claims.

Claims

1. A high-performance ceramic cutter head, characterized in that, By weight, it includes 5 - 7 parts of nano - composite 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 nano - composite powder is carbon nanotubes. The surface of the carbon nanotube matrix is successively modified with a first coating and a second coating. The first coating is a carbon - nitrogen coating, and the second coating is an in - situ grown silicon carbide layer.

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

3. A high-performance ceramic cutter head according to claim 1, wherein, 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 average particle size of the titanium boride is 1 - 2 μm, the average particle size of the alumina is 1 - 2 μm, the particle size of the magnesium oxide is 1.5 - 2.5 μm, and the particle size of the yttrium oxide is 1.5 - 2.5 μm.

4. A forming method of a high-performance ceramic cutter head according to any one of claims 1 to 3, characterized in that, It includes the following steps: (1) Acidify the carbon nanotubes to obtain acidified carbon nanotubes, then add the acidified carbon nanotubes to a mixed solution of glucose and urea, perform ultrasonic treatment, place the obtained reaction solution in a reaction kettle for hydrothermal reaction. After the reaction ends, centrifuge the hydrothermal reaction solution, wash the centrifugal precipitate and dry it to obtain a pre - coated carbon nanotube material; (2) Place the pre - coated carbon nanotube material in a tubular furnace for pyrolysis reaction to obtain a carbon nanotube material coated with the first coating; (3) Mix the above carbon nanotube material coated with the first coating with a polycarbosilane solution, perform ultrasonic treatment, then carry out curing treatment, crush and screen it, and place it in a tubular furnace for heat treatment to obtain a nano - composite powder; (4) According to the metering ratio, place the nano - composite powder, silicon carbide whiskers, titanium boride, alumina, sintering aid, and absolute ethanol in a ball - milling tank, use zirconia as the ball - milling medium for ball - milling treatment. Dry the slurry obtained by ball - milling, sieve it, place the obtained powder in a mold for pre - pressing treatment, and finally perform hot - press sintering on the green body obtained by pre - pressing treatment to obtain a ceramic tool.

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

1. The conditions for acidification treatment are refluxing at 80 °C for 3 - 6 h.

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

7. A forming method of a high-performance ceramic cutter head according to claim 4, characterized in that, In steps (1) and (3), the power of ultrasonic treatment is 200 - 300 W, and the time is 20 - 30 min; In step (2), the atmosphere of the pyrolysis reaction is an inert gas, the heating rate is 2 - 3 °C / min, the temperature is 800 - 900 °C, and the time is 1 - 2 h.

8. A method for forming a high-performance ceramic cutter head according to claim 4, 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 with the first coating to the polycarbosilane solution is 1:1; the temperature of the curing treatment is 200 °C, and the time is 1 - 2 h; the temperature of the heat treatment is 1200 °C, the heating rate is 4 - 5 °C / min, and the time is 1 - 2 h.

9. The forming method of a high-performance ceramic cutter head according to claim 4, 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 for pre-pressing treatment is room temperature, the pressure is 35 - 40 MPa, and the pressing time is 15 - 20 min.

10. The forming method of a high-performance ceramic cutter head according to claim 4, characterized in that, In step (4), the conditions for hot press sintering are as follows: First, heat up to 700 - 800 °C at a rate of 90 - 95 °C / min, then heat up to 1000 - 1050 °C / min at a rate of 85 - 88 °C / min, then heat up to 1150 - 1200 °C / min at a rate of 65 - 70 °C / min, and finally heat up to 1550 - 1580 °C at a rate of 40 - 43 °C / min, and keep the temperature for 5 - 10 min; the pressure for hot press sintering and forming is 30 - 40 MPa.

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