Reinforced wear-resistant Si3N4-BN-based composite ceramic cutting tool and preparation method thereof

Abstract

The application discloses a reinforced wear-resistant Si3N4-BN-based composite ceramic cutter and a preparation method thereof, and the raw material composition according to the weight percentage is as follows: 20-22wt% of alpha-Si3N4, 11-13wt% of gamma-Si3N4, 16-17wt% of r-BN, 13-15wt% of c-BN, 10-12wt% of Ti(C,N), 8-10wt% of TiC, 2.0-2.5wt% of Co, 3.0-3.5wt% of Ti, 2.0-2.5wt% of Mo, 1.5-2.0wt% of a sintering agent, 3.0-4.0wt% of a dispersing agent, 0.8-1.0wt% of a lubricant, 0.5-1.5wt% of a reinforcing agent, 1.3-2.5wt% of a coating material and 2.0-2.5wt% of a negative ion powder. The application takes Si3N4 and BN as the main base materials of the ceramic cutter, optimizes the formula design and the preparation process, improves the compactness and sintering property of the cutter, significantly improves the quality and performance of the composite ceramic cutter, and can well meet the high-precision turning machining requirement.

Description

Technical Field

[0001] This invention relates to the field of ceramic cutting tool technology, and in particular to a reinforced and wear-resistant Si3N4-BN-based composite ceramic cutting tool and its preparation method. Background Technology

[0002] With the rapid development and increasing demand in the automotive, aerospace, electronics, and energy sectors, the global turning market is continuously expanding. Furthermore, along with technological advancements, turning operations place increasingly higher demands on the quality of cutting tools, particularly in terms of high hardness, high toughness, and low wear. Cermet tools possess superior physical and chemical properties, making them more suitable for high-speed cutting and precision machining compared to traditional ceramic tools. However, current cermet tools still face many challenges in terms of materials and technology, such as uneven sintering, insufficient toughness, inadequate hardness, and high wear rates, making it difficult to meet the demands of high-precision turning operations.

[0003] Summary of the invention:

[0004] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a reinforced and wear-resistant Si3N4-BN-based composite ceramic cutting tool. Using Si3N4 and BN as the main matrix materials, and through optimized formulation design, the density and sintering properties of the tool are improved, thereby significantly enhancing the quality and performance of the composite ceramic cutting tool to meet the demands of high-precision turning. Another objective of this invention is to provide a method for preparing the aforementioned reinforced and wear-resistant Si3N4-BN-based composite ceramic cutting tool.

[0005] The objective of this invention is achieved through the following technical solution:

[0006] This invention provides a reinforced and wear-resistant Si3N4-BN-based composite ceramic cutting tool, whose raw material composition by weight percentage is: α-Si3N4 20-22wt%, γ-Si3N4 11-13wt%, γ-BN 16-17wt%, c-BN 13-15wt%, Ti(C,N) 10-12wt%, TiC 8-10wt%, Co 2.0-2.5wt%, Ti 3.0-3.5wt%, Mo 2.0-2.5wt%, sintering agent 1.5-2.0wt%, dispersant 3.0-4.0wt%, lubricant 0.8-1.0wt%, reinforcing agent 0.5-1.5wt%, coating material 1.3-2.5wt%, and negative ion powder 2.0-2.5wt%.

[0007] The sintering agent is a mixed powder with a mass ratio of titanium dioxide to zirconium oxide of 7–9:1; the dispersant is a mixed solution with a concentration of 0.5–2 wt% obtained by adding an ethanol medium to a mixed solution with a volume ratio of polyvinylpyrrolidone (PVP) to ethylene glycol of 4–6:1 and then subjecting it to ultrasonic vibration and mechanical stirring; the lubricant is silicon nitride; the reinforcing agent is a mixed powder with a mass ratio of alumina to yttrium oxide of 2–4:1–3; the coating material is tungsten carbide (WC); and the negative ion powder is tourmaline powder.

[0008] Furthermore, the particle sizes of the raw materials described in this invention are as follows: α-Si3N4 0.40–0.46 μm, γ-Si3N4 0.42–0.47 μm, r-BN 6–12 μm, c-BN 5–10 μm, Ti(C,N) 0.5–0.6 μm, TiC 1–5 μm, Co 2–3 μm, Ti 2–3 μm, Mo 2–3 μm, sintering agent 0.4–0.6 μm, lubricant 0.8–1.0 μm, reinforcing agent 0.4–0.8 μm, coating material 0.14–0.20 μm, and negative ion powder 0.6–1.2 μm.

[0009] Another objective of this invention is achieved through the following technical solution:

[0010] The preparation method of the above-mentioned reinforced wear-resistant Si3N4-BN-based composite ceramic cutting tool provided by the present invention includes the following steps:

[0011] (1) Preparation of mixed powder

[0012] According to the raw material composition, Ti(C,N) and TiC powders are mixed with a dispersant, and then α-Si3N4, γ-Si3N4, r-BN, c-BN, Co, Ti, Mo, sintering agent, lubricant, reinforcing agent, and negative ion powder are added and ball-milled for 48-72 hours. The resulting uniform slurry is dried at 100-120°C for 8-10 hours and then sieved to obtain a mixed powder.

[0013] (2) Cold isostatic pressing and low-temperature pre-sintering

[0014] The mixed powder is subjected to cold isostatic pressing technology, and the pressure is held at 150-200 MPa for 15-25 min. Then, the resulting green body is subjected to low-temperature pre-sintering, that is, the temperature is raised to 150-200℃ at a rate of 25℃ / min and held for 3-7 min, and then raised to 200-300℃ at a rate of 30℃ / min and held for 20-40 min to obtain a pre-sintered tool blank.

[0015] (3) Add coating and vacuum hot pressing sintering

[0016] The tool blank is cleaned to remove surface grease, and then placed in a vacuum chamber with the pressure controlled at 10. -3 ~10 -5 The coating material, i.e., solid WC powder, is heated to 3000-3500℃ by an electron gun to obtain tungsten carbide (WC) vapor atoms. After deposition for 1.5-2 hours, a coating is formed on the surface of the tool blank. The coated tool blank is then placed in a vacuum hot press and sintered under vacuum at a pressure of 150-200 MPa and a temperature of 1400-1600℃ for 1-1.5 hours to obtain a semi-finished tool.

[0017] (4) Finished product completed

[0018] The above-mentioned semi-finished cutting tools are laser-engraved, and the surface is rough-ground, fine-ground, polished, and sharpened to obtain the finished reinforced and wear-resistant Si3N4-BN-based composite ceramic cutting tool.

[0019] The present invention has the following beneficial effects:

[0020] (1) Si3N4 and BN materials themselves have excellent properties such as high hardness, strong bending resistance, and high wear resistance. Compared with traditional ceramic materials, Si3N4 and BN materials perform better under harsh conditions such as high temperature, high pressure, and high load. This invention optimizes the formula design, that is, using Si3N4 and BN as the matrix phase, and Ti(C,N) and TiC as the reinforcing phase; micron-sized TiC is mainly distributed inside the grains, serving as a nucleating agent for the matrix phases Si3N4 and BN; micron-sized Ti(C,N) is mainly distributed at the grain boundaries, preventing the migration of the matrix phase and improving the grain boundary density; Co, Ti, and Mo are used as binder phases, further improving the crystal density. The resulting Si3N4-BN-based composite ceramic cutting tool has significantly improved quality and performance.

[0021] (2) This invention uses Si3N4 and BN as the main matrix materials for ceramic cutting tools. First, a step-by-step heating process is performed for pre-sintering, which prevents grain growth and results in high hardness and toughness of the tool. Then, vacuum hot-pressing sintering is used to improve the phase purity of the material and enhance sintering uniformity, making the tool less prone to wear. The resulting Si3N4-BN-based composite cermet cutting tool exhibits high hardness, high toughness, and low wear (fracture toughness > 45 MPa·m). 1 / 2 With a hardness > 55HRC and wear rate < 6g, it not only improves the tool's service life but also well meets the requirements of high-precision turning tools. Attached Figure Description

[0022] The present invention will now be described in further detail with reference to the embodiments and accompanying drawings:

[0023] Figure 1This is a process flow diagram of the preparation process of the wear-resistant Si3N4-BN-based composite ceramic cutting tool according to an embodiment of the present invention. Detailed Implementation

[0024] This invention relates to a reinforced and wear-resistant Si3N4-BN-based composite ceramic cutting tool, the raw materials of which are ceramic materials, metal powder, additives, and other additives.

[0025] Among them, the ceramic materials contain α-Si3N4, γ-Si3N4, r-BN, c-BN, Ti(C,N), and TiC; the metal powders contain Co, Ti, and Mo; the additives contain sintering agents, dispersants, lubricants, and reinforcing agents; and other additives contain coating materials and negative ion powder.

[0026] The raw materials and their amounts used in the embodiments of the present invention are shown in Table 1; the raw material composition ratios of each embodiment are shown in Table 2.

[0027] Table 1. Raw materials used in the reinforced and wear-resistant Si3N4-BN-based composite ceramic cutting tools of the present invention.

[0028]

[0029]

[0030] The sintering agent is a mixed powder of titanium dioxide and zirconium oxide in a mass ratio of 8:1; the dispersant is a mixed solution of polyvinylpyrrolidone (PVP) and ethylene glycol in a volume ratio of 5:1, which is added to an ethanol medium and then mixed with ultrasonic vibration and mechanical stirring to obtain a 1wt% concentration; the lubricant is silicon nitride; the reinforcing agent is a mixed powder of alumina and yttrium oxide in a mass ratio of 3:2; the coating material is tungsten carbide (WC); and the negative ion powder is tourmaline powder.

[0031] Table 2. Raw material composition ratio of basalt fiber ceramic cutting tools in various embodiments of the present invention.

[0032]

[0033] This invention discloses a method for preparing a reinforced and wear-resistant Si3N4-BN-based composite ceramic cutting tool, as shown in the embodiment of the invention. Figure 1 As shown, the steps are as follows:

[0034] (1) Preparation of mixed powder

[0035] According to the raw material composition in Table 2, Ti(C,N) and TiC powders were mixed with a dispersant, and then α-Si3N4, γ-Si3N4, r-BN, c-BN, Co, Ti, Mo, sintering agent, lubricant, reinforcing agent, and negative ion powder were added. The mixture was ball-milled at a ratio of ball to material of 10:1 for 48–72 hours. The resulting uniform slurry was then fed into a microwave drying oven with an emission frequency of 2.7 GHz and an emission wavelength of 12.24 cm and dried at 100–120 °C for 8–10 hours. The slurry was then sieved through a 120-mesh sieve to obtain the mixed powder.

[0036] (2) Cold isostatic pressing and low-temperature pre-sintering

[0037] The above-mentioned mixed powder is poured into a prepared graphite mold, and cold isostatic pressing is used. Nitrogen is selected as the pressure medium. After the gas passes through the gas inlet, a spiral lifting mechanism is used to pressurize the medium. After pressurizing to 150-200 MPa, the pressure is held for 15-25 minutes to compact the powder and demold it. The demolded green blank is placed in a high-temperature furnace for low-temperature pre-sintering, that is, the temperature is raised to 150-200℃ at a rate of 25℃ / min and held for 3-7 minutes, and then raised to 200-300℃ at a rate of 30℃ / min and held for 20-40 minutes to obtain the pre-sintered tool blank.

[0038] (3) Add coating and vacuum hot pressing sintering

[0039] The tool blank was cleaned with MgCl solution to remove surface grease, and then placed in a vacuum chamber with the pressure controlled at 10. -3 ~10 -5 The coating material, solid tungsten carbide (WC) powder, is heated to 3000–3500°C using an electron gun to obtain tungsten carbide (WC) vapor atoms. After deposition for 1.5–2 hours, a tool blank with a coating is obtained. The coated tool blank is then placed in a vacuum hot press and sintered under vacuum at a pressure of 150–200 MPa and a temperature of 1400–1600°C for 1–1.5 hours to obtain a semi-finished tool.

[0040] (4) Finished product completed

[0041] The above-mentioned semi-finished cutting tools are laser-engraved, and the surface is rough-ground and fine-ground. The surface of the ground cutting tools is polished with diamond and sharpened to obtain the finished reinforced and wear-resistant Si3N4-BN-based composite ceramic cutting tool.

[0042] The preparation process parameters for each embodiment are shown in Table 3.

[0043] Table 3. Preparation process parameters of ceramic cutting tools in various embodiments of the present invention

[0044]

[0045] Performance testing:

[0046] Torque testing was performed using a torque sensor to detect the fracture toughness of the cutting tool; hardness testing was conducted using a Rockwell hardness tester; and cutting tests were performed to examine the tool wear. The performance indicators of the ceramic cutting tool in this embodiment are shown in Table 4.

[0047] Table 4 Performance indicators of ceramic cutting tools in various embodiments of the present invention

[0048]

Claims

1. A reinforced and wear-resistant Si3N4-BN-based composite ceramic cutting tool, characterized in that... The raw material composition by weight percentage is as follows: α-Si3N4 20-22wt%, γ-Si3N4 11-13wt%, r-BN 16-17wt%, c-BN 13-15wt%, Ti(C,N) 10-12wt%, TiC 8-10wt%, Co 2.0-2.5wt%, Ti 3.0-3.5wt%, Mo 2.0-2.5wt%, sintering agent 1.5-2.0wt%, dispersant 3.0-4.0wt%, lubricant 0.8-1.0wt%, reinforcing agent 0.5-1.5wt%, coating material 1.3-2.5wt%, and negative ion powder 2.0-2.5wt%. The sintering agent is a mixed powder of titanium dioxide and zirconium oxide in a mass ratio of 7–9:1; the dispersant is a mixed solution of polyvinylpyrrolidone and ethylene glycol in a volume ratio of 4–6:1, with a concentration of 0.5–2 wt%, obtained by ultrasonic vibration and mechanical stirring; the lubricant is silicon nitride; the reinforcing agent is a mixed powder of alumina and yttrium oxide in a mass ratio of 2–4:1–3; the coating material is tungsten carbide; and the negative ion powder is tourmaline powder.

2. The reinforced wear-resistant Si3N4-BN-based composite ceramic cutting tool according to claim 1, characterized in that: The raw materials consist of the following particle sizes: α-Si3N4 0.40–0.46 μm, γ-Si3N4 0.42–0.47 μm, r-BN 6–12 μm, c-BN 5–10 μm, Ti(C,N) 0.5–0.6 μm, TiC 1–5 μm, Co 2–3 μm, Ti 2–3 μm, Mo 2–3 μm, sintering agent 0.4–0.6 μm, lubricant 0.8–1.0 μm, reinforcing agent 0.4–0.8 μm, coating material 0.14–0.20 μm, and negative ion powder 0.6–1.2 μm.

3. The preparation method of the reinforced wear-resistant Si3N4-BN-based composite ceramic cutting tool according to claim 1 or 2, characterized in that... Includes the following steps: (1) Preparation of mixed powder According to the raw material composition, Ti(C,N) and TiC powders are mixed with a dispersant, and then α-Si3N4, γ-Si3N4, r-BN, c-BN, Co, Ti, Mo, sintering agent, lubricant, reinforcing agent, and negative ion powder are added and ball-milled for 48-72 hours. The resulting uniform slurry is dried at 100-120°C for 8-10 hours and then sieved to obtain a mixed powder. (2) Cold isostatic pressing and low-temperature pre-sintering The mixed powder is subjected to cold isostatic pressing technology, and the pressure is held at 150-200 MPa for 15-25 min. Then, the resulting green body is subjected to low-temperature pre-sintering, that is, the temperature is raised to 150-200℃ at a rate of 25℃ / min and held for 3-7 min, and then raised to 200-300℃ at a rate of 30℃ / min and held for 20-40 min to obtain a pre-sintered tool blank. (3) Add coating and vacuum hot pressing sintering The tool blank is cleaned to remove surface grease, and then placed in a vacuum chamber with the pressure controlled at 10. -3 ~10 - 5 Pa, the coating material, i.e., solid WC powder, is heated to 3000-3500℃ by an electron gun to obtain tungsten carbide (WC) vapor atoms, which are deposited for 1.5-2 hours, thereby forming a coating on the surface of the tool blank; then the coated tool blank is placed in a vacuum hot press and sintered under vacuum at a pressure of 150-200 MPa and a temperature of 1400-1600℃ for 1-1.5 hours to obtain a semi-finished tool; (4) Finished product completed The above-mentioned semi-finished cutting tools are laser-engraved, and the surface is rough-ground, fine-ground, polished, and sharpened to obtain the finished reinforced and wear-resistant Si3N4-BN-based composite ceramic cutting tool.

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