Low-metal-pollution cutter for rubber mixing process

Abstract

The invention relates to a low-metal-pollution cutter for a rubber mixing process, and belongs to the technical field of ceramic cutters. According to the low-metal-pollution cutter, silicon nitride serves as a main component, a multi-layer structure and the network-shaped outer wrapping layer are designed, the network-shaped outer wrapping layer takes composite fibers as a frame, a Si-Al-O-N liquid phase is formed by adding a composite sintering aid, densified sintering is achieved, meanwhile, the sintering temperature is reduced, energy consumption is reduced, and the low-metal-pollution cutter has the advantages of being high in yield and good in performance. In addition, the network arrangement structure of the fibers not only improves the toughness, but also does not have pores. Therefore, when the prepared low-metal-pollution cutter is stressed, the low-metal-pollution cutter is diffused from the transverse direction and the longitudinal direction, the longitudinal force is dissipated from the outer layer to the inner layer through multiple layers of silicon nitride under mechanical deformation, the transverse force is eliminated by reducing stress concentration, crack deflection and fiber fracture, and then the toughness, the abrasion resistance and the compactness of the material are improved from multiple dimensions.

Description

Technical Field

[0001] This invention belongs to the field of ceramic cutting tool technology and relates to a low-metal-pollution cutting tool for use in the rubber compounding process. Background Technology

[0002] Most industrial mixing blades are made of metal. Although high-speed steel blades possess high mechanical strength, friction during rubber mixing can cause metal to leach into the rubber, leading to excessive metal content. To address this, using ceramic blades with high hardness, high wear resistance, and no metal contamination fundamentally avoids the introduction of iron, manganese, and other metallic impurities due to blade wear when cutting or mixing rubber products. This effectively reduces the metal content of rubber products, improving product quality and consistency, and is particularly suitable for the production of specialty rubbers with strict requirements on metal content.

[0003] Ceramics are materials with excellent properties such as high strength, high hardness, high temperature resistance, wear resistance, corrosion resistance, and electrical insulation, making them ideal for extreme environments. Si3N4 ceramics are one of the important structural ceramic materials. Although they have excellent properties, their brittleness and tendency to fracture are significant drawbacks. Therefore, many existing technologies utilize microstructure design, fiber reinforcement, and element doping to improve the fracture toughness of silicon nitride ceramics. Summary of the Invention

[0004] This invention relates to a low-metal-contamination cutting tool for use in rubber compounding processes, belonging to the field of ceramic cutting tool technology. The low-metal-contamination cutting tool disclosed in this invention uses silicon nitride as the main component, designed with a multi-layer structure and a network-like outer coating. The network-like outer coating uses composite fibers as a framework, and by adding composite sintering aids, a Si-Al-ON liquid phase is formed, achieving densification sintering while reducing sintering temperature and energy consumption. Furthermore, the network arrangement of the fibers not only improves its toughness but also eliminates porosity. Therefore, the low-metal-contamination cutting tool prepared by this invention, when subjected to force, disperses both laterally and longitudinally. The longitudinal force is dissipated through multiple layers of silicon nitride from the outside to the inside under mechanical deformation, while the lateral force is eliminated by reducing stress concentration, crack deflection, and fiber breakage, thereby improving the material's toughness, wear resistance, and density from multiple dimensions.

[0005] The objective of this invention can be achieved through the following technical solutions: A low-metal-contamination cutting tool for use in the rubber compounding process, the low-metal-contamination cutting tool is composed of a multi-layer internal structure and a network-like outer coating structure, wherein the multi-layer internal structure is layered silicon nitride, and the network-like outer coating is a composite fiber framework and a silicon carbide-based composite material filling layer.

[0006] Furthermore, the method for preparing the low-metal-contamination cutting tool includes the following steps: (1) Silicon nitride, aluminum oxide, yttrium oxide, binder, toughening agent and silicon carbide are mixed and ball-milled to obtain casting slurry, which is then cast into a casting sheet by a casting machine; (2) The cast film is neatly arranged and placed into the mold. Then, the organic matter is removed by heating and nitrogen is introduced. After hot pressing and sintering, multilayer silicon nitride is obtained. (3) After sandblasting, multilayer silicon nitride is pretreated and placed back into the mold. Slurry is added for filling, followed by hot pressing and sintering. After heat preservation, it is cooled to room temperature and removed from the mold to become a low-metal contamination tool.

[0007] Further, in step (1), the mass ratio of silicon nitride, aluminum oxide, yttrium oxide, binder, toughening agent and silicon carbide is 90-100:3-5:6:3-8:10:20, the ball milling time is 10-12h, the fineness of the cast slurry is 2-4μm, and the casting speed of the casting machine is 0.2-0.25m / min.

[0008] Further, the thickness of the cast sheet in step (2) is 200-400μm, the temperature and time of the heating are 500-600℃ and 30-40min respectively, and the temperature, pressure and time of the hot pressing sintering are 1750-1850℃, 20-25MPa and 60-90min respectively.

[0009] Further, in step (3), the surface roughness of the pretreated multilayer silicon nitride is 20-50 μm, the mass ratio of the pretreated multilayer silicon nitride to the slurry is 25-30:2-5, the temperature, pressure and time of the hot pressing sintering treatment are 1400-1450℃, 20-25MPa and 60-90min respectively, and the temperature and time of the heat preservation are 1400℃ and 1-2h respectively.

[0010] Further, the preparation method of the slurry in step (3) is as follows: PCS, composite sintering aid, composite fiber and silicon carbide are mixed and ball-milled, and ultrasonically treated to obtain the slurry.

[0011] Furthermore, the mass ratio of the PCS, composite sintering aid, composite fiber and silicon carbide is 3-5:0.5:0.8:1-2, wherein the composite sintering aid is composed of aluminum nitride and ytterbium oxide in a mass ratio of 1:1-2, and the composite fiber is composed of basalt fiber and carbon fiber in a mass ratio of 1:1.

[0012] Furthermore, the ball milling time and fineness are 10-12h and 1-3μm, respectively, and the ultrasonic treatment time is 15-20min.

[0013] The beneficial effects of this invention are: 1. The low-metal-contamination cutting tool disclosed in this invention uses silicon nitride as the main component, designed with a multi-layer structure and a network-like outer cladding. The network-like outer cladding uses composite fibers as a framework, and by adding composite sintering aids, a Si-Al-ON liquid phase is formed, achieving densification sintering while reducing sintering temperature and energy consumption. Furthermore, the network arrangement of the fibers not only improves its toughness but also eliminates porosity. The composite fibers enhance toughness through both crystalline and amorphous phases. Therefore, the low-metal-contamination cutting tool prepared by this invention, when subjected to force, disperses both laterally and longitudinally. The longitudinal force is dissipated through multiple layers of silicon nitride from the outside to the inside under mechanical deformation, while the lateral force is eliminated by reducing stress concentration, crack deflection, and fiber breakage. This, in turn, improves the material's toughness, wear resistance, and density from multiple dimensions. Detailed Implementation

[0014] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features and effects of the present invention, in conjunction with embodiments, is provided below.

[0015] The binder involved in this invention is PVB, purchased from Wuhan Lanabai Pharmaceutical Chemical Co., Ltd., CAS No. 63148-65-2; the toughening agent is dioctyl phthalate; the basalt fiber is purchased from Eryu (Shijiazhuang) New Material Technology Co., Ltd., model STER-07; the carbon fiber is purchased from Shanghai Lishuo Composite Materials Technology Co., Ltd., with a length of 1mm; the traditional high-speed steel cutting tool is purchased from Suzhou Zongque New Material Technology Co., Ltd., item number W56-66-36.

[0016] Example 1 A low-metal-contamination cutting tool for use in the rubber compounding process, the low-metal-contamination cutting tool is composed of a multi-layer internal structure and a network-like outer coating structure, wherein the multi-layer internal structure is layered silicon nitride, and the network-like outer coating is a composite fiber framework and a silicon carbide-based composite material filling layer.

[0017] The method for preparing the low-metal-contamination cutting tool includes the following steps: (1) Silicon nitride, aluminum oxide, yttrium oxide, binder, toughening agent and silicon carbide are mixed and ball-milled to obtain casting slurry, which is then cast into a casting sheet by a casting machine; (2) The cast film is neatly arranged and placed into the mold. Then, the organic matter is removed by heating and nitrogen is introduced. After hot pressing and sintering, multilayer silicon nitride is obtained. (3) After sandblasting, multilayer silicon nitride is pretreated and placed back into the mold. Slurry is added for filling, followed by hot pressing and sintering. After heat preservation, it is cooled to room temperature and removed from the mold to become a low-metal contamination tool.

[0018] In step (1), the mass ratio of silicon nitride, aluminum oxide, yttrium oxide, binder, toughening agent and silicon carbide is 90:3:6:3:10:20, the ball milling time is 10h, the fineness of the cast slurry is 2μm, and the casting speed of the casting machine is 0.2m / min.

[0019] The thickness of the cast sheet in step (2) is 200 μm, the temperature and time of the heating are 500℃ and 30 min respectively, and the temperature, pressure and time of the hot pressing sintering are 1750℃, 20 MPa and 60 min respectively.

[0020] In step (3), the surface roughness of the pretreated multilayer silicon nitride is 20 μm, the mass ratio of the pretreated multilayer silicon nitride to the slurry is 25:2, the temperature, pressure and time of the hot pressing sintering treatment are 1400℃, 20MPa and 60min respectively, and the temperature and time of the heat preservation are 1400℃ and 1h respectively.

[0021] The preparation method of the slurry in step (3) is as follows: PCS, composite sintering aid, composite fiber and silicon carbide are mixed and ball-milled, and ultrasonically treated to obtain the slurry.

[0022] The mass ratio of PCS, composite sintering aid, composite fiber and silicon carbide is 3:0.5:0.8:1, wherein the composite sintering aid is composed of aluminum nitride and ytterbium oxide in a mass ratio of 1:1, and the composite fiber is composed of basalt fiber and carbon fiber in a mass ratio of 1:1.

[0023] The ball milling time and fineness are 10h and 1μm, respectively, and the ultrasonic treatment time is 15min.

[0024] Example 2 A low-metal-contamination cutting tool for use in the rubber compounding process, the low-metal-contamination cutting tool is composed of a multi-layer internal structure and a network-like outer coating structure, wherein the multi-layer internal structure is layered silicon nitride, and the network-like outer coating is a composite fiber framework and a silicon carbide-based composite material filling layer.

[0025] The method for preparing the low-metal-contamination cutting tool includes the following steps: (1) Silicon nitride, aluminum oxide, yttrium oxide, binder, toughening agent and silicon carbide are mixed and ball-milled to obtain casting slurry, which is then cast into a casting sheet by a casting machine; (2) The cast film is neatly arranged and placed into the mold. Then, the organic matter is removed by heating and nitrogen is introduced. After hot pressing and sintering, multilayer silicon nitride is obtained. (3) After sandblasting, multilayer silicon nitride is pretreated and placed back into the mold. Slurry is added for filling, followed by hot pressing and sintering. After heat preservation, it is cooled to room temperature and removed from the mold to become a low-metal contamination tool.

[0026] In step (1), the mass ratio of silicon nitride, aluminum oxide, yttrium oxide, binder, toughening agent and silicon carbide is 95:4:6:5.5:10:20, the ball milling time is 11h, the fineness of the cast slurry is 3μm, and the casting speed of the casting machine is 0.23m / min.

[0027] The thickness of the cast sheet in step (2) is 300 μm, the temperature and time of the heating are 550 °C and 35 min respectively, and the temperature, pressure and time of the hot pressing sintering are 1800 °C, 23 MPa and 75 min respectively.

[0028] In step (3), the surface roughness of the pretreated multilayer silicon nitride is 35 μm, the mass ratio of the pretreated multilayer silicon nitride to the slurry is 28:3.5, the temperature, pressure and time of the hot pressing sintering treatment are 1425℃, 23MPa and 75min respectively, and the temperature and time of the heat preservation are 1400℃ and 1.5h respectively.

[0029] The preparation method of the slurry in step (3) is as follows: PCS, composite sintering aid, composite fiber and silicon carbide are mixed and ball-milled, and ultrasonically treated to obtain the slurry.

[0030] The mass ratio of PCS, composite sintering aid, composite fiber and silicon carbide is 4:0.5:0.8:1.5, wherein the composite sintering aid is composed of aluminum nitride and ytterbium oxide in a mass ratio of 1:1.5, and the composite fiber is composed of basalt fiber and carbon fiber in a mass ratio of 1:1.

[0031] The ball milling time and fineness were 11 hours and 2 μm, respectively, and the ultrasonic treatment time was 18 minutes.

[0032] Example 3 A low-metal-contamination cutting tool for use in the rubber compounding process, the low-metal-contamination cutting tool is composed of a multi-layer internal structure and a network-like outer coating structure, wherein the multi-layer internal structure is layered silicon nitride, and the network-like outer coating is a composite fiber framework and a silicon carbide-based composite material filling layer.

[0033] The method for preparing the low-metal-contamination cutting tool includes the following steps: (1) Silicon nitride, aluminum oxide, yttrium oxide, binder, toughening agent and silicon carbide are mixed and ball-milled to obtain casting slurry, which is then cast into a casting sheet by a casting machine; (2) The cast film is neatly arranged and placed into the mold. Then, the organic matter is removed by heating and nitrogen is introduced. After hot pressing and sintering, multilayer silicon nitride is obtained. (3) After sandblasting, multilayer silicon nitride is pretreated and placed back into the mold. Slurry is added for filling, followed by hot pressing and sintering. After heat preservation, it is cooled to room temperature and removed from the mold to become a low-metal contamination tool.

[0034] In step (1), the mass ratio of silicon nitride, aluminum oxide, yttrium oxide, binder, toughening agent and silicon carbide is 100:5:6:8:10:20, the ball milling time is 12h, the fineness of the cast slurry is 4μm, and the casting speed of the casting machine is 0.25m / min.

[0035] The thickness of the cast sheet in step (2) is 400 μm, the temperature and time of the heating are 600 °C and 40 min respectively, and the temperature, pressure and time of the hot pressing sintering are 1850 °C, 25 MPa and 90 min respectively.

[0036] In step (3), the surface roughness of the pretreated multilayer silicon nitride is 50 μm, the mass ratio of the pretreated multilayer silicon nitride to the slurry is 30:5, the temperature, pressure and time of the hot pressing sintering treatment are 1450℃, 25MPa and 90min respectively, and the temperature and time of the heat preservation are 1400℃ and 2h respectively.

[0037] The preparation method of the slurry in step (3) is as follows: PCS, composite sintering aid, composite fiber and silicon carbide are mixed and ball-milled, and ultrasonically treated to obtain the slurry.

[0038] The mass ratio of PCS, composite sintering aid, composite fiber and silicon carbide is 5:0.5:0.8:2, wherein the composite sintering aid is composed of aluminum nitride and ytterbium oxide in a mass ratio of 1:2, and the composite fiber is composed of basalt fiber and carbon fiber in a mass ratio of 1:1.

[0039] The ball milling time and fineness were 12 hours and 3 μm, respectively, and the ultrasonic treatment time was 20 minutes.

[0040] Comparative Example 1 Based on Example 2, a low-metal-pollution cutting tool for the rubber mixing process is provided. The low-metal-pollution cutting tool consists of a multi-layer internal structure and a network-like outer coating structure. The multi-layer internal structure is layered silicon nitride, and the network-like outer coating is a composite fiber frame and a silicon carbide-based composite material filler layer.

[0041] The method for preparing the low-metal-contamination cutting tool includes the following steps: (1) Silicon nitride, aluminum oxide, yttrium oxide, binder, toughening agent and silicon carbide are mixed and ball-milled to obtain casting slurry, which is then cast into a casting sheet by a casting machine; (2) The cast film is neatly arranged and placed into the mold. Then, the organic matter is removed by heating and nitrogen is introduced. After hot pressing and sintering, a low-metal contamination tool is obtained.

[0042] In step (1), the mass ratio of silicon nitride, aluminum oxide, yttrium oxide, binder, toughening agent and silicon carbide is 95:4:6:5.5:10:20, the ball milling time is 11h, the fineness of the cast slurry is 3μm, and the casting speed of the casting machine is 0.23m / min.

[0043] The thickness of the cast sheet in step (2) is 300 μm, the temperature and time of the heating are 550 °C and 35 min respectively, and the temperature, pressure and time of the hot pressing sintering are 1800 °C, 23 MPa and 75 min respectively.

[0044] Comparative Example 2 Based on Example 2, the basalt fiber in the composite fiber used in the slurry preparation process was removed and replaced with an equal mass of carbon fiber, while other conditions remained the same as in Example 2.

[0045] Comparative Example 3 Based on Example 2, the carbon fibers in the composite fibers used in the slurry preparation process were removed and replaced with basalt fibers of equal mass, while other conditions remained the same as in Example 2.

[0046] Comparative Example 4 Based on Example 2, aluminum nitride in the composite sintering aid used in the slurry preparation process was removed and replaced with an equal mass of ytterbium oxide, while other conditions remained the same as in Example 2.

[0047] Comparative Example 5 Based on Example 2, ytterbium oxide in the composite sintering aid used in the slurry preparation process was removed and replaced with an equal mass of aluminum nitride, while other conditions remained the same as in Example 2.

[0048] Comparative Example 6 Based on Example 2, a low-metal-pollution cutting tool for the rubber mixing process is provided. The low-metal-pollution cutting tool consists of a multi-layer internal structure and a network-like outer coating structure. The multi-layer internal structure is layered silicon nitride, and the network-like outer coating is a composite fiber frame and a silicon carbide-based composite material filler layer.

[0049] The method for preparing the low-metal-contamination cutting tool includes the following steps: (1) Silicon nitride, aluminum oxide, yttrium oxide, binder, toughening agent and silicon carbide are mixed and ball-milled to obtain casting slurry, which is then cast into a casting sheet by a casting machine; (2) The cast film is neatly arranged and placed into the mold. Then, the organic matter is removed by heating and nitrogen is introduced. After hot pressing and sintering, multilayer silicon nitride is obtained. (3) Multilayer silicon nitride is added to the slurry for filling, followed by hot pressing and sintering. After heat preservation, it is cooled to room temperature and removed from the mold to become a low-metal contamination tool.

[0050] In step (1), the mass ratio of silicon nitride, aluminum oxide, yttrium oxide, binder, toughening agent and silicon carbide is 95:4:6:5.5:10:20, the ball milling time is 11h, the fineness of the cast slurry is 3μm, and the casting speed of the casting machine is 0.23m / min.

[0051] The thickness of the cast sheet in step (2) is 300 μm, the temperature and time of the heating are 550 °C and 35 min respectively, and the temperature, pressure and time of the hot pressing sintering are 1800 °C, 23 MPa and 75 min respectively.

[0052] In step (3), the mass ratio of multilayer silicon nitride to slurry is 28:3.5. The temperature, pressure and time of the hot pressing sintering treatment are 1425℃, 23MPa and 75min respectively. The temperature and time of the heat preservation are 1400℃ and 1.5h respectively.

[0053] The preparation method of the slurry in step (3) is as follows: PCS, composite sintering aid, composite fiber and silicon carbide are mixed and ball-milled, and ultrasonically treated to obtain the slurry.

[0054] The mass ratio of PCS, composite sintering aid, composite fiber and silicon carbide is 4:0.5:0.8:1.5, wherein the composite sintering aid is composed of aluminum nitride and ytterbium oxide in a mass ratio of 1:1.5, and the composite fiber is composed of basalt fiber and carbon fiber in a mass ratio of 1:1.

[0055] The ball milling time and fineness were 11 hours and 2 μm, respectively, and the ultrasonic treatment time was 18 minutes.

[0056] Comparative Example 7 Based on Example 2, the mass ratio of pretreated multilayer silicon nitride to slurry was adjusted to 28:7, while other conditions remained the same as in Example 2.

[0057] Comparative Example 8 Based on Example 2, the mass ratio of pretreated multilayer silicon nitride to slurry was adjusted to 28:1.5, while other conditions remained the same as in Example 2.

[0058] Performance testing The low-metal contamination cutting tools prepared in Examples 1-3 and Comparative Examples 1-8 were used as samples. The microstructure of the sample surface was characterized using an S-3400N scanning electron microscope to observe whether there were pores. Mechanical testing: The Vickers hardness and fracture toughness of the samples were determined by indentation testing using an automatic Vickers hardness tester, with a load of 1 kgf and a holding time of 10 s. The wear resistance of the samples was tested using a multi-functional friction and wear testing machine, with a load of 110 N, a sliding speed of 60 mm / s, a friction stroke of 2-3 mm, a friction frequency of 10 Hz, and a test time of 30 min. After the experiment, the samples were removed, and the mass difference before and after wear was measured using a precision electronic balance (accuracy 0.1 mg) to calculate the wear rate. The calculation formula is: W = (m2 - m1) / (FL), where W is the wear rate (mg / N·m), F is the load (N), L is the total sliding distance, m2 is the mass before wear, and m1 is the mass after wear. The test results are shown in Table 1. Metal content test: Rubber was mixed using a conventional high-speed steel knife and a low-metal contamination knife prepared in Example 2 of this invention, and samples of the same batch of styrene-butadiene rubber were taken to test the metal content; the test results are shown in Table 2.

[0059] Table 1 Test Results Analysis of the results in Table 1 shows that no pores were observed on the surfaces of Examples 1-3 and Comparative Examples 1-8. The low-metal contamination cutting tool made in Comparative Example 1 was a multilayer silicon nitride without a network-like outer cladding, resulting in a significant decrease in hardness, fracture toughness, and wear rate. Comparative Examples 2-3 used a single sintering aid, which increased the temperature requirement and prevented the formation of a Si-Al-ON liquid phase under the original temperature and composition, thus reducing hardness, fracture toughness, and wear rate. Comparative Examples 4-5 added a single fiber, reducing the toughening pathway and significantly weakening fracture toughness. The reduced toughness compromised the protective performance of the outer layer, leading to decreased wear resistance. Comparative Example 6 removed the sandblasting step of the multilayer silicon nitride, resulting in a smooth surface that hindered slurry adhesion, leading to poor fracture toughness and wear resistance. Comparative Examples 7-8 adjusted the mass ratio of the multilayer internal structure to the network-like outer cladding structure. When the proportion of the outer structure was too high, the hardness decreased significantly because the outer structure was based on a fiber framework. When the proportion of the outer structure was too low, the outer layer was too thin, reducing its protective effect and lowering fracture toughness and wear rate.

[0060] Table 2 Results of Metal Content Test As can be seen from Table 2, the metal content of the low-metal contamination cutting tool prepared in Example 2 of the present invention is much lower than that of traditional high-speed steel cutting tools. The low-metal contamination cutting tool prepared by the present invention effectively reduces the metal content of rubber products and improves the quality and consistency of the products.

[0061] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A low-metal-contamination cutting tool for use in the rubber compounding process, characterized in that, The low-metal contamination cutting tool consists of a multi-layer internal structure and a network-like outer cladding structure. The multi-layer internal structure is layered silicon nitride, and the network-like outer cladding is a composite fiber framework with a silicon carbide-based composite material filling layer.

2. The low-metal-contamination cutting tool for rubber compounding process according to claim 1, characterized in that, The method for preparing the low-metal-contamination cutting tool includes the following steps: (1) Silicon nitride, aluminum oxide, yttrium oxide, binder, toughening agent and silicon carbide are mixed and ball-milled to obtain casting slurry, which is then cast into a casting sheet by a casting machine; (2) The cast film is neatly arranged and placed into the mold. Then, the organic matter is removed by heating and nitrogen is introduced. After hot pressing and sintering, multilayer silicon nitride is obtained. (3) After sandblasting, multilayer silicon nitride is pretreated and placed back into the mold. Slurry is added for filling, followed by hot pressing and sintering. After heat preservation, it is cooled to room temperature and removed from the mold to become a low-metal contamination tool.

3. A low-metal-contamination cutting tool for rubber compounding process according to claim 2, characterized in that, In step (1), the mass ratio of silicon nitride, aluminum oxide, yttrium oxide, binder, toughening agent and silicon carbide is 90-100:3-5:6:3-8:10:20, the ball milling time is 10-12h, the fineness of the cast slurry is 2-4μm, and the casting speed of the casting machine is 0.2-0.25m / min.

4. A low-metal-contamination cutting tool for rubber mixing process according to claim 2, characterized in that, The thickness of the cast sheet in step (2) is 200-400μm, the temperature and time of the heating are 500-600℃ and 30-40min respectively, and the temperature, pressure and time of the hot pressing sintering are 1750-1850℃, 20-25MPa and 60-90min respectively.

5. A low-metal-contamination cutting tool for rubber compounding process according to claim 2, characterized in that, In step (3), the surface roughness of the pretreated multilayer silicon nitride is 20-50 μm, the mass ratio of the pretreated multilayer silicon nitride to the slurry is 25-30:2-5, the temperature, pressure and time of the hot pressing sintering treatment are 1400-1450℃, 20-25MPa and 60-90min respectively, and the temperature and time of the heat preservation are 1400℃ and 1-2h respectively.

6. A low-metal-contamination cutting tool for rubber mixing process according to claim 2, characterized in that, The preparation method of the slurry in step (3) is as follows: PCS, composite sintering aid, composite fiber and silicon carbide are mixed and ball-milled, and ultrasonically treated to obtain the slurry.

7. A low-metal-contamination cutting tool for rubber mixing process according to claim 6, characterized in that, The mass ratio of PCS, composite sintering aid, composite fiber and silicon carbide is 3-5:0.5:0.8:1-2, wherein the composite sintering aid is composed of aluminum nitride and ytterbium oxide in a mass ratio of 1:1-2, and the composite fiber is composed of basalt fiber and carbon fiber in a mass ratio of 1:

1.

8. A low-metal-contamination cutting tool for rubber mixing process according to claim 6, characterized in that, The ball milling time and fineness are 10-12h and 1-3μm, respectively, and the ultrasonic treatment time is 15-20min.

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