A layer-network structure TiCN / W18Cr4V high-speed steel composite material and its preparation method

Abstract

The present invention discloses a TiCN / W18Cr4V high-speed steel composite material and a preparation method thereof. The preparation method of the composite material comprises the following steps: preparing a three-dimensionally ordered TiCN layered porous ceramic skeleton by using a bidirectional freezing mold, and completely immersing W18Cr4V high-speed steel into the TiCN layered porous ceramic skeleton by means of gas pressure infiltration to obtain a layer-network structure TiCN / W18Cr4V high-speed steel cutting tool composite material. Due to various toughening mechanisms caused by the layer-network structure, such as ceramic / metal layer synergistic plastic deformation, ligament bridging, crack blunting and multi-crack propagation, the composite material proposed by the present invention has good fracture toughness, and also exhibits high hardness and excellent wear resistance, and is an ideal material for making high-strength and tough cutting tools.

Description

Technical field:

[0001] The present invention relates to the technical field of high-speed steel composite materials, and in particular to a layer-net structure TiCN / W18Cr4V high-speed steel composite material and a preparation method thereof. Background technology:

[0002] With the rapid development of advanced manufacturing industries such as aerospace, automotive, and 5G electronic communications, materials are evolving toward lightweight, corrosion-resistant, high-strength, and fatigue-resistant materials. Machining is also evolving toward high precision, high cutting speeds, and high productivity, placing increasing demands on cutting tools for accuracy, lifespan, and environmental friendliness. Traditional tool materials, such as high-speed steel, offer excellent toughness but struggle to withstand extended service at high temperatures. Ceramic tools offer excellent hardness, wear resistance, and red hardness, but are susceptible to tool failure under large temperature swings or high impact loads. Coated tools offer both toughness and wear resistance, but the coatings are susceptible to delamination or peeling when working with hard materials or at excessively high temperatures. Consequently, cutting tools are required to maintain excellent toughness while improving their hardness, wear resistance, impact resistance, and lifespan to meet the demands of efficient and high-precision cutting. Summary of the invention:

[0003] The present invention solves the problems existing in the prior art and provides a layer-network structure TiCN / W18Cr4V high-speed steel composite material and a preparation method thereof. Thanks to the multiple toughening mechanisms caused by the layer-network structure, the composite material has good fracture toughness, high hardness, excellent wear resistance and impact resistance by regulating the ceramic content. The composite material can be applied in the field of cutting tools to meet the needs of efficient cutting and high-precision cutting.

[0004] The purpose of the present invention is to provide a two-way freezing mold, comprising a polytetrafluoroethylene tank for placing slurry, a metal tank connected to the top of the polytetrafluoroethylene tank, and an insulation plate arranged between the polytetrafluoroethylene tank and the metal tank, a metal plate is provided at the bottom of the metal tank, the metal plate passes through the insulation plate and enters the polytetrafluoroethylene tank, and a heat-conducting liquid tank is provided at the top of the metal tank to conduct heat out of the polytetrafluoroethylene tank.

[0005] Preferably, the heat insulation plate is a polytetrafluoroethylene plate, and a sealing plate is provided between the heat insulation plate and the polytetrafluoroethylene groove to seal the polytetrafluoroethylene groove and the metal groove.

[0006] The heat-conducting liquid tank is provided with a liquid that performs heat conduction. In the present invention, alcohol is preferably provided in the heat-conducting liquid tank. The metal in the metal tank and the metal plate is a heat-conducting metal. In the present invention, the metal tank is preferably a copper tank and the metal plate is a copper plate.

[0007] The present invention also protects a method for preparing a layer-network structured TiCN / W18Cr4V high-speed steel composite material, which includes the following steps: using the bidirectional freezing mold to prepare a three-dimensionally ordered TiCN layered porous ceramic framework, and adopting gas pressure infiltration to completely immerse W18Cr4V high-speed steel into the TiCN layered porous ceramic framework to obtain a layer-network structured TiCN / W18Cr4V high-speed steel cutting tool composite material.

[0008] During the infiltration process, the ceramic lamellae of the TiCN layered porous ceramic framework basically remain intact, while the interlayer pores and the intra-layer pores are completely filled with the molten W18Cr4V high-speed steel, respectively forming a primary layered structure and a secondary network structure. This composite material can be given high hardness and excellent wear resistance by adjusting the volume fraction of the ceramic powder, and is an ideal material for making high-strength and tough cutting tools.

[0009] Preferably, the preparation method specifically includes the following steps:

[0010] (1) Powder mixing: Pour TiCN powder and TiH2 powder into a container, then add water, ammonium polyacrylate, and neutral silica sol, and stir evenly under vacuum to obtain a slurry with uniformly dispersed ceramic particles;

[0011] (2) Freezing: Place the bidirectional freezing mold in a freezing container at -30°C - (-35°C), then pour the slurry obtained in step (1) and freeze for 1.0 - 1.5 hours. After demolding, a green body with alternating ceramic layers and ice layers is obtained;

[0012] (3) Low-temperature drying: Dry the green body at low temperature for 24 - 48 hours;

[0013] (4) Sintering: Sinter the low-temperature dried green body under the protection of an inert gas to obtain a TiCN layered porous ceramic framework;

[0014] (5) Infiltration: Place the TiCN layered porous ceramic framework and the W18Cr4V high-speed steel block into a graphite mold in sequence, then place the mold into a vacuum reaction container. First, evacuate to below 10 Pa at room temperature, heat up to 1550°C and hold the temperature, then introduce high-purity argon into the vacuum furnace to allow the metal liquid to infiltrate into the ceramic framework to obtain a layer-network structured TiCN / W18Cr4V high-speed steel composite material.

[0015] Preferably, in step (1), TiCN accounts for 20% - 30% of the total volume of the slurry, TiH2 accounts for 1% - 1.5% of the total volume of the slurry, ammonium polyacrylate accounts for 1% - 1.5% of the total volume of the slurry, and neutral silica sol accounts for 0.8% - 1% of the total volume of the slurry.

[0016] The conditions of the low-temperature drying described in step (3) are low temperature (i.e., temperature < -60°C) and low pressure (i.e., pressure < 10 Pa).

[0017] Preferably, the mass ratio of the TiCN layered porous ceramic skeleton to the W18Cr4V high-speed steel block described in step (5) is 1:4 - 7.

[0018] Preferably, the specific steps of step (4) are as follows: First, put the green body after low-temperature drying into a vacuum sintering furnace, then pump out the air in the sintering furnace. When the vacuum gauge value reaches below -0.1 MPa, continuously introduce inert gas with a purity of 99.9% into the vacuum furnace, keep the air pressure at 0 MPa, conduct atmospheric pressure sintering, heat up at a rate of 8 - 12°C / min, keep the temperature at 500°C for 25 - 35 minutes, at 1000°C for 0.8 - 1.2 hours, and at 1500°C for 1.8 - 2.2 hours. Finally, cool the temperature to 300°C at a cooling rate of 8 - 12°C / min and then cool with the furnace to obtain the TiCN layered porous ceramic skeleton.

[0019] Preferably, the freezing container in step (2) is a refrigerator, and the inert gas in step (4) is argon.

[0020] The present invention also protects the TiCN / W18Cr4V high-speed steel composite material with a layer-network structure obtained by the above preparation method.

[0021] The present invention also protects the application of the above layer-network structure TiCN / W18Cr4V high-speed steel composite material in tools.

[0022] The present invention also protects a layer-network structure TiCN / W18Cr4V high-speed steel tool composite material. Cut the TiCN / W18Cr4V high-speed steel composite material into tool heads and perform grinding and polishing to obtain the layer-network structure TiCN / W18Cr4V high-speed steel tool composite material.

[0023] Compared with the prior art, the present invention has the following advantages:

[0024] (1) Compared with the existing composite tool materials, the present invention uses an environmentally friendly two-way freeze-casting method to construct the TiCN ceramic skeleton, and can control the lamellar morphology of the ceramic skeleton by adjusting factors such as freezing temperature, additives, ceramic content, powder particle size, and sintering temperature, so as to regulate the comprehensive performance of the composite material to meet the tool material selection under various working conditions.

[0025] (2) Benefiting from various toughening mechanisms such as ceramic / metal layer synergistic plastic deformation, ligament bridging, crack blunting, and multi-crack propagation caused by the layer-network structure, the composite material has good fracture toughness, high hardness, excellent wear resistance, and impact resistance.

[0026] (3) After the tool manufactured by the present invention is worn, it only needs to use a grinding wheel to grind off the metal layer before continuing to process parts, which greatly improves the life of the tool and processing efficiency. Description of the drawings:

[0027] Figure 1 It is a structural schematic diagram of the bidirectional freezing mold proposed by the present invention.

[0028] Figure 2 This is the macroscopic morphology of the fracture of the ceramic skeleton after sintering in Example 1.

[0029] Figure 3 The microscopic morphology of the fracture of the preform after sintering, where (a) is the transverse fracture, (b) is the longitudinal fracture, and (c) and (d) are local enlarged views.

[0030] Figure 4 This is a metallographic diagram of the tool head.

[0031] Figure 5 This is a model of a tool made of a layer-net structure TiCN / W18Cr4V composite material.

[0032] Figure 6 3 is a comparison chart of the wear performance of the layer-network structure TiCN / W18Cr4V composite material obtained in Examples 1-3 and W18Cr4V high-speed steel.

[0033] Explanation of the accompanying reference numerals: 1. Polytetrafluoroethylene tank; 2. Sealing plate; 3. Heat insulation plate; 4. Metal plate; 5. Metal tank; 6. Alcohol; 7. Heat-conducting liquid tank; 8. Tool handle; 9. Tool head; 10. Ceramic layer; 11. Metal layer. Specific implementation method:

[0034] The following examples are provided to further illustrate the present invention, but are not intended to limit the present invention.

[0035] Unless otherwise defined, all technical terms used hereinafter have the same meanings as those generally understood by those skilled in the art. The technical terms used herein are for the purpose of describing specific embodiments only and are not intended to limit the scope of protection of the present invention. Unless otherwise specified, the experimental materials and reagents herein are conventional commercial products in the art.

[0036] The bidirectional freezing mold used in the following embodiments includes a polytetrafluoroethylene tank 1 for placing the slurry, a metal tank 5 connected to the top of the polytetrafluoroethylene tank, and an insulation plate 3 arranged between the polytetrafluoroethylene tank 1 and the metal tank 5. A metal plate 4 is provided at the bottom of the metal tank 5, and the metal plate 4 passes through the insulation plate 3 and enters the polytetrafluoroethylene tank 1. A heat-conducting liquid tank 7 is provided on the top of the metal tank 5 to conduct heat out of the polytetrafluoroethylene tank 1.

[0037] In essence, the heat insulation board proposed by the present invention can be any board that can achieve the heat insulation effect. In the following embodiments, it is preferred that the heat insulation board 3 is a polytetrafluoroethylene board. A sealing plate 2 for sealingly connecting the polytetrafluoroethylene groove and the metal groove is provided between the heat insulation board and the polytetrafluoroethylene groove.

[0038] A liquid for heat conduction is provided in the heat conduction liquid groove 7. In the present invention, it is preferred that alcohol 6 is provided in the heat conduction liquid groove 7. The metals in the metal groove 5 and the metal plate 4 are heat-conducting metals. In the present invention, it is preferred that the metal groove 5 is a copper groove and the metal plate 4 is a copper plate.

[0039] In the two-way freezing mold proposed by the present invention, the heat in the slurry is conducted to the copper groove through the copper plate, and the alcohol accelerates the heat export. The temperature difference between the upper and lower parts of the copper plate forms a vertical temperature gradient, and the temperature difference between the slurry in the polytetrafluoroethylene groove and the slurry near the copper plate forms a horizontal temperature gradient, thereby forming a two-way temperature gradient. When in use, the two-way freezing mold is placed in a refrigerator at -35°C, in which the copper groove and the copper plate are connected and together with the alcohol form a heat conduction module to form a two-way temperature gradient. The polytetrafluoroethylene plate and the sealing plate are used to isolate cold air, and the slurry is placed in the polytetrafluoroethylene groove.

[0040] The materials used in the following embodiments include TiCN powder, TiH2 powder, ammonium polyacrylate, silica sol, deionized water and W18Cr4V high-speed steel, and the specific information is shown in Table 1.

[0041] Table 1 Specific information of the materials used

[0042]

[0043] Example 1

[0044] A preparation method of a layer-network structure TiCN / W18Cr4V high-speed steel tool composite material includes the following steps:

[0045] (1) Powder mixing: Weigh 52.63 g of TiCN and 2.03 g of TiH2 powder and pour them into a beaker, then add 40 mL of deionized water, 0.55 g of ammonium polyacrylate and 0.49 g of neutral silica sol, and then place the beaker on a magnetic stirrer and stir evenly under vacuum to obtain a slurry with a certain viscosity and evenly dispersed ceramic particles.

[0046] (2) Freezing: First, place the two-way freezing mold ( Figure 1 ) in a refrigerator at -35°C for 30 minutes, and then pour in the stirred slurry and freeze for 1 hour. After demolding, a green body with alternating ceramic layers and ice layers is obtained.

[0047] (3) Low-temperature drying: Place the green body in a freeze-drying device and perform freeze-drying in an environment of low temperature and low pressure (< -60°C, < 10 Pa), and the drying time is 48 h.

[0048] (4) Sintering: First, place the green body into a vacuum sintering furnace, then evacuate the air in the sintering furnace. When the value on the vacuum gauge reaches below -0.1 MPa, continuously introduce argon with a purity of 99.9% into the vacuum furnace, keep the air pressure at 0 MPa, and conduct atmospheric pressure sintering. The sintering curve is as follows: heat up at a rate of 10 °C / min, hold for 30 minutes at 500 °C, 1 hour at 1000 °C, and 2 hours at 1500 °C. Finally, cool the temperature to 300 °C at a cooling rate of 10 °C / min and then cool with the furnace to finally obtain a TiCN porous ceramic skeleton with a certain strength( Figure 2 ), and it can be seen from Figure 2 that the lamellar arrangement of the ceramic skeleton is long-range ordered.

[0049] (5) Infiltration: Place the TiCN porous ceramic skeleton and the W18Cr4V high-speed steel block with a mass ratio of 1:7 into a graphite mold in sequence, and then place the mold into a vacuum furnace. First, evacuate to below 10 Pa at room temperature, heat to 1550 °C at a rate of 5 °C / min, and hold for 15 min. Then introduce high-purity argon into the vacuum furnace to form a high pressure above the molten metal liquid, while the internal pores of the ceramic skeleton below are still in a vacuum state. Utilize the internal and external pressure difference to make the metal liquid infiltrate into the ceramic skeleton, hold the pressure for 5 min, and then cool to room temperature at a rate of 10 °C / min.

[0050] (6) Cutting: Use a wire electrical discharge machine to cut the infiltrated TiCN / W18Cr4V high-speed steel composite material into tool heads( Figure 5 ), and then carry out grinding and polishing. It can be seen from Figure 5 that the tool includes a tool handle 8 and a tool head 9. The tool head 9 adopts a splicing design, in which the black ceramic layer 10 and the white metal layer 11 are alternately and orderly arranged. When machining a part, use the ceramic layer 10 as the main cutting edge. When the ceramic layer 10 is worn, the metal layer 11 can be ground off with a grinding wheel and then the part can be machined continuously.

[0051] Morphology characterization: The theoretical ceramic content of this embodiment is 20 vol.%, but the porous ceramic usually undergoes a certain volume shrinkage during the sintering process, resulting in its porosity being unable to be estimated based on the initial ceramic solid content. Therefore, the Archimedes drainage method is used to measure that the actual porosity of the ceramic skeleton is 76 vol.%( Figure 2 ); Use a scanning electron microscope of model SUPRA55 produced by ZEISS Company in Germany to observe the micro morphology of the porous ceramic skeleton( Figure 3 ); Microstructure: Use a metallographic optical microscope of XD30M series produced by Ningbo Shunyu Instrument Co., Ltd. to observe the metallography of the specimen( Figure 4 ), and it can be seen from Figure 4It can be seen that the black ceramic layer and the white metal layer are arranged alternately, and the metal also fills the fine pores in the ceramic sheet layer to form a primary layered and secondary network structure.

[0052] Performance test: The hardness of the specimen was measured using a Rockwell hardness tester. First, the tested surface of the specimen was polished with 1000-mesh sandpaper. The average value of multiple-point tests was taken as the final hardness value, and the tested surface was parallel to the bottom surface to avoid large fluctuations in hardness readings, thereby affecting the experimental accuracy. The flexural strength of the specimen was determined using an INSTRON 3369 electronic universal material testing machine. The specimen size was 5 mm × 5 mm × 25 mm. The impact toughness of the specimen was tested using a pendulum impact toughness testing machine. The specimen size for impact toughness testing was a non-notch long strip specimen of 5 × 5 × 50 mm, prepared by wire electrical discharge machining. The four tested surfaces of the specimen were polished with 1000-mesh sandpaper. The wear resistance of high-speed steel and the composite material was tested using an HT-1000 friction and wear testing machine respectively. The test parameters were as follows: rotational speed was 800 r / min, load was 6 N, time was 300 min, friction radius was 10 mm, and a Si3N4 ball with a diameter of 4 mm was selected as the friction pair. After the friction test, the volume wear amount of the specimen was measured using a wear scar instrument, and the wear amounts of the composite materials with different ceramic contents were compared to compare the changes in friction performance. The test results of the ceramic content, fracture strength, impact toughness, and hardness of this composite material are shown in Table 2, and the friction and wear performance is shown in Figure 6 .

[0053] Example 2

[0054] A preparation method of a layer-network structure TiCN / W18Cr4V high-speed steel composite material, comprising the following steps:

[0055] (1) Powder mixing: Weigh 71.04 g of TiCN and 2.84 g of TiH2 powders and pour them into a beaker. Then add 40 mL of deionized water, 0.77 g of ammonium polyacrylate, and 0.60 g of neutral silica sol. Then place the beaker on a magnetic stirrer and stir evenly under vacuum to obtain a slurry with a certain viscosity and evenly dispersed ceramic particles.

[0056] (2) Freezing: First, place the self-made two-way freezing mold in a refrigerator at -35 °C for 30 minutes, then pour in the stirred slurry and freeze for 1 hour. After demolding, a green body with alternating ceramic layers and ice layers is obtained.

[0057] (3) Low-temperature drying: Place the green body in a freeze-drying device and conduct freeze-drying in a low-temperature and low-pressure (< -60 °C, < 10 Pa) environment. The drying time is 48 h.

[0058] (4) Sintering: First, place the green body into a vacuum sintering furnace, then evacuate the air in the sintering furnace. When the value on the vacuum gauge reaches below -0.1 MPa, continuously introduce argon with a purity of 99.9% into the vacuum furnace, keep the air pressure at 0 MPa, and conduct atmospheric pressure sintering. The sintering curve is as follows: heat up at a rate of 10 °C / min, hold for 30 minutes at 500 °C, 1 hour at 1000 °C, and 2 hours at 1500 °C. Finally, cool the temperature to 300 °C at a cooling rate of 10 °C / min and then cool with the furnace to finally obtain a TiCN porous ceramic skeleton with a certain strength.

[0059] (5) Infiltration: Place the TiCN ceramic skeleton and the W18Cr4V high-speed steel block with a mass ratio of 1:5 into a self-made graphite mold in sequence, and then place the mold into a vacuum furnace. First, evacuate to below 10 Pa at room temperature, heat to 1550 °C at a rate of 5 °C / min, and hold for 15 min. Then introduce high-purity argon into the vacuum furnace to form a high pressure above the molten metal liquid, while the pores inside the ceramic skeleton below are still in a vacuum state. Utilize the internal and external pressure difference to make the metal liquid infiltrate into the ceramic skeleton, hold the pressure for 5 min, and then cool to room temperature at a rate of 10 °C / min.

[0060] (6) Cutting: Use a wire electrical discharge machining cutter to cut the infiltrated TiCN / W18Cr4V high-speed steel composite material into tool heads, and then perform grinding and polishing.

[0061] Microstructure and property testing: The theoretical ceramic content of this example is 25 vol.%, and the actual porosity of the TiCN ceramic skeleton is measured to be 71 vol.% by the Archimedes drainage method; the methods for testing its microstructure and properties are the same as those in Example 1. The test results of the ceramic content, fracture strength, impact toughness, and hardness properties are shown in Table 2, and the friction and wear properties are shown in Figure 6 .

[0062] Example 3

[0063] A preparation method of a layer-network structure TiCN / W18Cr4V high-speed steel tool composite material, comprising the following steps:

[0064] (1) Powder mixing: Weigh 92.04 g of TiCN and 3.55 g of TiH2 powders and pour them into a beaker. Then add 40 mL of deionized water, 0.97 g of ammonium polyacrylate, and 0.72 g of neutral silica sol. Then place the beaker on a magnetic stirrer and stir evenly under vacuum to obtain a slurry with a certain viscosity and evenly dispersed ceramic particles.

[0065] (2) Freezing: First, place the self-made two-way freezing mold in a refrigerator at -35 °C for 30 minutes, then pour in the stirred slurry and freeze for 1 hour. After demolding, obtain a green body with alternating ceramic layers and ice layers.

[0066] (3) Low-temperature drying: Put the green body into a freeze-drying device and conduct freeze-drying in an environment of low temperature and low pressure (< -60 °C, < 10 Pa). The drying time is 48 h.

[0067] (4) Sintering: First, put the green body into a vacuum sintering furnace, then pump out the air in the sintering furnace. When the vacuum gauge value reaches below -0.1 MPa, continuously introduce argon with a purity of 99.9% into the vacuum furnace, keep the air pressure at 0 MPa, and conduct atmospheric pressure sintering. The sintering curve is as follows: Heat up at a rate of 10 °C / min, keep warm at 500 °C for 30 minutes, 1000 °C for 1 hour, and 1500 °C for 2 hours. Finally, cool the temperature to 300 °C at a cooling rate of 10 °C / min and then cool with the furnace to finally obtain a TiCN porous ceramic skeleton with a certain strength.

[0068] (5) Infiltration: Put the TiCN ceramic skeleton and W18Cr4V high-speed steel block with a mass ratio of 1:4 into a self-made graphite mold in sequence, and put the mold into a vacuum furnace. First, evacuate to below 10 Pa at room temperature, heat to 1550 °C at a rate of 5 °C / min, and keep warm for 15 min. Then introduce high-purity argon into the vacuum furnace to form a high pressure above the molten metal liquid, while the internal pores of the ceramic skeleton below are still in a vacuum state. Use the internal and external pressure difference to make the metal liquid infiltrate into the ceramic skeleton, keep warm and pressurize for 5 min, and then cool to room temperature at a rate of 10 °C / min.

[0069] (6) Cutting: Use a wire electrical discharge machine to cut the infiltrated TiCN / W18Cr4V high-speed steel composite material into tool heads, and conduct grinding and polishing.

[0070] Microstructure and property testing: The ceramic content of this example is 30 vol.%. The actual porosity of the TiCN ceramic skeleton is measured to be 66 vol.% by the Archimedes drainage method. The methods for testing its microstructure and properties are the same as those in Example 1. The test results of the ceramic content, fracture strength, impact toughness, and hardness properties are shown in Table 2, and the friction and wear properties are shown in Figure 6 .

[0071] Comparative Example 1

[0072] Cut the W18Cr4V high-speed steel as follows and conduct tests:

[0073] The hardness of the specimens was measured using a Rockwell hardness tester. First, the tested surface of the specimen to be tested was polished with 1000-mesh sandpaper. The average value of multiple-point tests was taken as the final hardness value, and the tested surface was parallel to the bottom surface to avoid large fluctuations in hardness readings, thereby affecting the experimental accuracy. The flexural strength of the specimens was determined using an INSTRON 3369 electronic universal material testing machine. The specimen size was 5 mm × 5 mm × 25 mm. The impact toughness of the specimens was tested using a pendulum impact toughness testing machine. The specimen size for impact toughness testing was a non-notch long strip specimen of 5 × 5 × 50 mm, prepared by wire electrical discharge machining. The four tested surfaces of the specimens were polished with 1000-mesh sandpaper. The wear resistance of high-speed steel and composites was tested using an HT-1000 friction and wear testing machine. The test parameters were as follows: rotational speed was 800 r / min, load was 6 N, time was 300 min, friction radius was 10 mm, and a Si3N4 ball with a diameter of 4 mm was selected as the friction pair. After the friction test, the volume wear amount of the specimens was measured using a wear scar instrument. The test results of the fracture strength, impact toughness, and hardness properties are shown in Table 2, and the friction and wear properties are shown in Figure 6 .

[0074] Comparative Example 2

[0075] The method for fabricating TiCN (42 vol.%)-based ceramic tool materials by vacuum hot pressing is as follows:

[0076] WC cemented carbide balls were placed in a ball-to-powder mass ratio of 8:1, and then an appropriate amount of absolute ethanol was added and the ball mill jar was sealed. The composite powder (mass percentage: TiCN - 30%, Co - 17.5%, Mo - 10.5%, Fe - 42%) was dried in a vacuum drying oven at 100 °C. After drying, the composite powder was passed through a 200-mesh stainless steel sieve and then pressed into a graphite mold with a diameter of 60 mm. The graphite mold containing the composite powder was placed in a ZT-40-20 type vacuum hot pressing sintering furnace for sintering. The heating process for vacuum hot pressing the tool material was as follows: It was heated from room temperature to the set sintering temperature of 1400 °C at a heating rate of 10 °C / min and then held for 3 h. After that, heating was stopped and it was cooled with the furnace to obtain the TiCN-based ceramic tool material. The pressurization process was as follows: The powder was pre-pressed and pressure was maintained before sintering, and the pre-pressing pressure was 10 MPa. When sintering for a certain duration (120 min), since the sintering temperature increased and the composite powder began to soften, slow pressurization started at this time. When the holding temperature was reached, the sintering pressure was increased to 30 MPa and pressure was maintained. When the holding time ended, the pressure was removed, that is, the external pressure was 0 at this time. During the entire sintering process, the material to be sintered was in a vacuum environment, and the vacuum degree was between (1.2 - 2.4) × 10 -3 Pa.

[0077] Comparative Example 3

[0078] The method for fabricating TiCN (90 vol.%) - based ceramic cutting tool materials by vacuum hot pressing is as follows:

[0079] WC cemented carbide balls are placed in a ball - to - material mass ratio of 8:1, and then an appropriate amount of absolute ethanol is added. After sealing the ball - milling tank, continuous ball - milling is carried out on a ball mill for 72 h. Then, the composite powder (mass percentages: TiCN - 82%, HfC - 10%, Co - 4%, Ni - 4%) is dried in a vacuum drying oven at 100 °C. After the dried composite powder passes through a 200 - mesh stainless - steel wire sieve, it is pressed into a graphite mold with a diameter of 60 mm. The graphite mold containing the composite powder is placed in a ZT - 40 - 20 type vacuum hot - pressing sintering furnace for sintering. The heating process of the vacuum hot - pressed sintered cutting tool material is as follows: It is heated from room temperature to the set sintering temperature of 1400 °C at a heating rate of 10 °C / min and then starts to hold the temperature. After holding the temperature for 3 h, heating is stopped and it is cooled with the furnace to obtain the TiCN - based ceramic cutting tool material. The pressurization process is as follows: The powder is pre - pressed and the pressure is maintained before sintering, and the pre - pressing pressure is 10 MPa. When sintering for a certain duration (120 min), due to the increase in sintering temperature, the composite powder begins to soften. At this time, slow pressurization starts. When the holding temperature is reached, the sintering pressure is increased to 30 MPa and the pressure is maintained. When the holding time ends, the pressure is removed, that is, the external pressure is 0 at this time. During the whole sintering process, the material to be sintered is in a vacuum environment, and the vacuum degree is between (1.2 - 2.4)×10 -3 Pa. The mechanical properties of the composite materials obtained in Examples 1 - 3 and Comparative Examples 1 - 3 are tested, and the test results are shown in Table 2 and Figure 6 as follows.

[0080] Table 2 Test results of the performance of the composite materials

[0081]

[0082] With the increase in the ceramic content, the hardness increases, but the flexural strength decreases significantly, which is inevitable. Benefiting from various toughening mechanisms caused by the layer - network structure, such as ceramic / metal layer synergistic plastic deformation, ligament bridging, crack blunting, and multi - crack propagation, the hardness and wear resistance of this composite material are significantly improved with the increase in ceramic content, and it can also maintain good flexural strength.

[0083] Compared with the performance of traditional high - speed steel, the hardness and wear resistance of the high - speed steel proposed in this invention are significantly improved, and the wear resistance is 2.5 times higher than that of W18Cr4V high - speed steel (the wear resistance is shown in Figure 6 ). Compared with TiCN - based ceramic cutting tools made by powder metallurgy, this invention greatly improves its flexural strength on the basis of ensuring high hardness and good wear resistance to meet the requirements of high - efficiency cutting and high - precision cutting.

[0084] The description of the above embodiments is only used to help understand the technical solution and its core idea of the present invention. It should be noted that for those skilled in the art of this technology, without departing from the principle of the present invention, several improvements and modifications can still be made to the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims

1. A preparation method of a layer-network structure TiCN / W18Cr4V high-speed steel composite material, characterized in that The specific steps include: (1) Powder mixing: Pour TiCN powder and TiH2 powder into a container, then add water, ammonium polyacrylate and neutral silica sol, and stir evenly under vacuum to obtain a slurry in which ceramic particles are evenly dispersed. The TiCN accounts for 20%-30% of the total volume of the slurry, the TiH2 accounts for 1%-1.5% of the total volume of the slurry, the ammonium polyacrylate accounts for 1%-1.5% of the total volume of the slurry, and the neutral silica sol accounts for 0.8%-1% of the total volume of the slurry; (2) Freezing: Place the bidirectional freezing mold in a freezing container at -30°C to (-35°C), then pour the slurry obtained in step (1) into it and freeze for 1.0-1.5 hours. After demolding, a green body with alternating ceramic layers and ice layers is obtained; (3) Low temperature drying: Dry the green body at low temperature for 24-48 hours; (4) Sintering: The green body after low-temperature drying is sintered under inert gas protection to obtain a TiCN layered porous ceramic skeleton; (5) Impregnation: The TiCN layered porous ceramic skeleton and the W18Cr4V high-speed steel block are placed in the mold in sequence, and then the mold is placed in a vacuum reaction vessel. The vacuum is first evacuated to below 10 Pa at room temperature, and the temperature is raised to 1500℃-1600℃ and kept warm. Then, high-purity argon gas is introduced into the vacuum furnace to allow the metal liquid to penetrate into the ceramic skeleton to obtain a layer-net structure TiCN / W18Cr4V high-speed steel composite material; the bidirectional freezing mold includes a polytetrafluoroethylene tank for placing the slurry, a metal tank connected to the top of the polytetrafluoroethylene tank, and an insulation plate arranged between the polytetrafluoroethylene tank and the metal tank. A metal plate is arranged at the bottom of the metal tank, and the metal plate passes through the insulation plate and enters the polytetrafluoroethylene tank. A heat-conducting liquid tank is arranged at the top of the metal tank to conduct heat out of the polytetrafluoroethylene tank.

2. The preparation method according to claim 1, characterized in that, The heat insulation plate is a polytetrafluoroethylene plate, and a sealing plate is provided between the heat insulation plate and the polytetrafluoroethylene groove to seal the polytetrafluoroethylene groove and the metal groove.

3. The preparation method according to claim 1, wherein The mass ratio of the TiCN layered porous ceramic skeleton and the W18Cr4V high-speed steel block in step (5) is 1:4-7.

4. The preparation method according to claim 1, characterized in that, The specific steps of step (4) are as follows: first, the green body after low-temperature drying is placed in a vacuum sintering furnace, and then the air in the sintering furnace is extracted. When the vacuum gauge value reaches below -0.1 MPa, an inert gas with a purity of 99.9% is continuously introduced into the vacuum furnace, and the gas pressure is maintained at 0 MPa. Normal pressure sintering is performed, and the temperature is increased at a rate of 8-12 ° C / min, and the temperature is kept at 500 ° C for 25-35 minutes, 1000 ° C for 0.8-1.2 hours, and 1500 ° C for 1.8-2.2 hours. Finally, the temperature is reduced to 300 ° C at a cooling rate of 8-12 ° C / min and then cooled in the furnace to obtain a TiCN layered porous ceramic skeleton.

5. The preparation method according to claim 1 obtains a layer-network structure TiCN / W18Cr4V high-speed steel composite material.

6. Use of the layer-network structure TiCN / W18Cr4V high-speed steel composite material according to claim 5 in cutting tools.

7. A layer-network structure TiCN / W18Cr4V high-speed steel tool composite material, characterized in that, Cut the TiCN / W18Cr4V high-speed steel composite material described in claim 5 into tool heads, and perform grinding and polishing to obtain the layer-network structure TiCN / W18Cr4V high-speed steel tool composite material.

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