WO2020186752A1 - Method for preparing superfine grain wc-co hard alloy by means of plasma ball milling - Google Patents

Method for preparing superfine grain wc-co hard alloy by means of plasma ball milling Download PDF

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WO2020186752A1
WO2020186752A1 PCT/CN2019/112876 CN2019112876W WO2020186752A1 WO 2020186752 A1 WO2020186752 A1 WO 2020186752A1 CN 2019112876 W CN2019112876 W CN 2019112876W WO 2020186752 A1 WO2020186752 A1 WO 2020186752A1
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ball milling
cemented carbide
plasma
powder
plasma ball
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PCT/CN2019/112876
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French (fr)
Chinese (zh)
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曾美琴
涂佳亮
鲁忠臣
胡仁宗
朱敏
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华南理工大学
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C1/00—Making non-ferrous alloys
    • C22C1/04—Making non-ferrous alloys by powder metallurgy
    • C22C1/05—Mixtures of metal powder with non-metallic powder
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C29/00—Alloys based on carbides, oxides, nitrides, borides, or silicides, e.g. cermets, or other metal compounds, e.g. oxynitrides, sulfides
    • C22C29/02—Alloys based on carbides, oxides, nitrides, borides, or silicides, e.g. cermets, or other metal compounds, e.g. oxynitrides, sulfides based on carbides or carbonitrides
    • C22C29/06—Alloys based on carbides, oxides, nitrides, borides, or silicides, e.g. cermets, or other metal compounds, e.g. oxynitrides, sulfides based on carbides or carbonitrides based on carbides, but not containing other metal compounds
    • C22C29/08—Alloys based on carbides, oxides, nitrides, borides, or silicides, e.g. cermets, or other metal compounds, e.g. oxynitrides, sulfides based on carbides or carbonitrides based on carbides, but not containing other metal compounds based on tungsten carbide

Definitions

  • the invention belongs to the technical field of cemented carbide and powder metallurgy, and in particular relates to a method for preparing ultrafine-crystalline WC-Co cemented carbide by plasma ball milling.
  • WC-Co cemented carbide is the earliest and most mature cemented carbide. Because of its high hardness, wear resistance and transverse fracture strength, it is widely used in cutting, molds, wear-resistant parts and mining tools. And other fields. In industry, W and C are often used as raw materials. First, WC is synthesized through high temperature carbonization at 1400°C, and then mixed with Co for long-term ball milling to prepare WC-Co composite powder, then granulation, pressing, dewaxing, and finally high temperature sintering. After two high-temperature treatments, WC has grown severely and it is difficult to prepare ultra-fine-grained cemented carbide.
  • Tungsten-cobalt oxide and carbon black are used as raw materials, and the cemented carbide is prepared by in-situ synthesis, pressing and sintering after ordinary ball milling. .
  • This method uses ordinary ball milling with low efficiency, low activity of the powder after ball milling, and high in-situ synthesis temperature required.
  • the particle size of the synthesized WC powder is coarse. Only on the basis of adding a grain growth inhibitor, the average particle size is Only reached 210nm.
  • new sintering technologies such as microwave sintering and plasma sintering can produce ultra-fine WC cemented carbide at a lower sintering temperature even with ordinary ball milling pretreatment, these new sintering equipment is more expensive than current production equipment.
  • a method for preparing ultrafine WC-Co cemented carbide by plasma ball milling is provided, which solves the technical problems of high temperature for in-situ synthesis of nano-WC powder and high subsequent sintering temperature.
  • the main purpose of the present invention is to provide a method for preparing ultrafine WC-Co cemented carbide by plasma ball milling.
  • the invention prepares highly active WO 3 -C composite powder in a very short ball milling time, can significantly reduce the temperature of in-situ synthesis of nano WC powder and the subsequent sintering temperature, and prepare ultrafine WC-Co hard with fine grains alloy.
  • the technical scheme of the present invention is: using WO 3 and graphite as raw materials, pretreatment by plasma discharge ball milling, and then putting it into a vacuum sintering furnace to synthesize high purity nano WC powder in situ, and finally mixing with Co, ball milling, pressing, and sintering to prepare super Fine-grained WC-Co cemented carbide.
  • the method has short ball milling time and low in-situ synthesis temperature, can realize rapid in-situ preparation of ultra-fine grained WC-Co cemented carbide, and has outstanding industrial application value.
  • a method for preparing ultrafine WC-Co cemented carbide by plasma ball milling includes the following steps:
  • step (3) The nano-WC-Co composite powder obtained in step (2) is pressed and sintered to obtain the ultra-fine grained WC-Co cemented carbide.
  • the weight ratio of WO 3 and graphite in step (1) is 80-85:15-20.
  • the amount of the absolute ethanol added in step (1) is 1 to 3 wt% of the total mass of WO 3 and graphite.
  • the parameters of the plasma ball mill in step (1) are: the ball-to-material ratio is 15:1-50:1, the ball milling time is 3h-10h, the speed of the ball mill is 960-1400rpm, and the plasma discharge atmosphere is 5. ⁇ 10 3 ⁇ 1 ⁇ 10 5 Pa, the dielectric constant of the dielectric barrier is 2 ⁇ 10, and the thickness of the dielectric barrier is 3 ⁇ 5mm.
  • the heating temperature in step (1) is 950 to 1150° C.
  • the heating time is 1-2 h
  • the heating pressure is 1 ⁇ 10 -3 to 1 ⁇ 10 -4 Pa.
  • the particle size of WO 3 in step (1) is 5-10 ⁇ m.
  • the amount of carbon supplement in step (2) is 0.2-0.3 wt% of the total mass of nano-WC powder and Co.
  • the particle size of Co in step (2) is 30-50 ⁇ m.
  • the time for performing plasma ball milling again in step (2) is 1 to 3 hours.
  • the pressing pressure in step (3) is 100-150 MPa.
  • the sintering temperature in step (3) is 1350 to 1410° C., and the sintering time is 1 to 2 hours.
  • the step (3) vacuum sintering or sintering the low pressure sintering, and more preferably, the low pressure sintering is 4 ⁇ 5Mpa, the pressure of the vacuum sintering 1 ⁇ 10 -3 ⁇ 5 ⁇ 10 - 3 Pa.
  • the present invention has the following advantages and beneficial effects:
  • the present invention uses cheap WO 3 instead of expensive elemental W as raw material, which can effectively reduce production costs. At the same time, it can synthesize nano-scale granular WC powder with high specific surface area and high activity by using the in-situ reaction characteristics of graphite and WO 3 , To prepare for the preparation of ultra-fine grained WC cemented carbide.
  • the present invention adopts plasma discharge ball milling, which can significantly improve ball milling efficiency, shorten ball milling time, and avoid impurity pollution caused by ball milling. Because plasma discharge ball milling combines mechanical energy and plasma field energy, plasma ionization electron adsorption powder On the surface of the body, graphite easily forms a super-flaky structure under the action of plasma, which increases the reaction interface area of WO 3 /C, which can significantly refine and activate WO 3 and graphite composite powders, effectively reducing WO 3 and graphite in situ The reaction temperature avoids the growth of WC at high temperatures, thereby synthesizing nano-WC powder.
  • the low-pressure sintering technology used in the present invention can effectively promote the powder densification process.
  • a nearly fully dense bulk cemented carbide can be prepared. Therefore, WC grains can be effectively avoided.
  • the sintering temperature is too high or the holding time is too long and it grows up seriously.
  • the final grain size of cemented carbide WC is only 350 ⁇ 450nm, which belongs to the ultrafine grain range.
  • Figure 1 is a process flow diagram of the preparation method of the present invention.
  • Fig. 2 is an SEM image of the WO 3 -C composite powder prepared in step (1) in embodiment 1 of the present invention.
  • Figure 3 is an XRD pattern of the WO 3 -C composite powder prepared in step (1) in Example 3 of the present invention.
  • Figure 4 is a DSC-TG chart of the nano-WO 3 -C composite powder prepared in step (1) in Example 1 of the present invention.
  • Fig. 5 is an XRD pattern of the nano-WC powder prepared in step (2) in Example 2 of the present invention.
  • Fig. 6 is an SEM image of the nano-WC powder prepared in step (2) in Example 2 of the present invention.
  • Fig. 7 is an XRD pattern of the WC-10Co cemented carbide prepared in step (3) in Example 2 of the present invention.
  • FIG. 8 is an SEM image of the WC-8Co cemented carbide prepared in step (3) in Example 4 of the present invention.
  • FIG. 9 is an SEM image of the WC-8Co cemented carbide prepared in step (3) in Example 4 of the present invention after polishing.
  • Fig. 10 is a distribution diagram of the WC grain size in the WC-8Co cemented carbide prepared in step (3) in Example 4 of the present invention.
  • the grinding balls are cemented carbide grinding balls
  • the tank body is a cemented carbide lining stainless steel tank
  • the total volume of the grinding balls accounts for 30%-50% of the volume of the ball milling tank.
  • the specific diameter and size of the grinding balls and the proportion of the total number of grinding balls are as follows: 22mm grinding balls account for 15%, 15mm grinding balls account for 25%, 10mm grinding balls account for 30%, and 6mm grinding balls account for 30%.
  • the volume of the ball milling powder occupies 40% of the gap between the grinding balls, the ball-grinding material ratio is 15:1-50:1, the discharge voltage is 15KV, and the discharge current is 1.5A.
  • the vibration block adopts a double amplitude of 5mm and the ball milling speed is 960rpm ⁇ 1400rpm. .
  • the electrode rod uses plastic king as the dielectric barrier layer and has a thickness of 3mm, a ball-to-material ratio of 15:1, a ball milling speed of 960rpm, and a ball milling time of 6h to obtain a highly active nano-WO 3 -C composite powder.
  • step (2) Place the nano-WO 3 -C composite powder obtained in step (1) in a vacuum tube sintering furnace, evacuate to 1 ⁇ 10 -3 Pa, and heat up to 950°C at a heating rate of 10°C/min ,Hold for 1h to make graphite and WO 3 fully react to obtain nano-WC powder.
  • step (3) The nano-WC powder obtained in step (2) is then mixed with Co according to the composition of WC-12Co, and 0.3% of the total mass of WC powder and Co is added, and plasma ball milling is performed for 3 hours, and finally a uniform mixture is obtained
  • the WC-Co composite powder is finally pressed and vacuum sintered at 1350°C for 1 hour to obtain the ultrafine crystalline WC-12Co cemented carbide according to the present invention.
  • the pressing force is 100MPa, and the vacuum sintering pressure is 1 ⁇ 10 -3 Pa.
  • the WC grain size in the WC-12Co cemented carbide prepared in this embodiment is 650-750 nm. According to XRD analysis, the phase composition is WC and Co, and the density is 98.2%.
  • the electrode rod uses plastic king as the dielectric barrier layer and has a thickness of 4 mm, a ball-to-material ratio of 30:1, a ball milling speed of 1400 rpm, and a ball milling time of 6 hours to obtain nano-WO 3 -C composite powder.
  • step (2) Place the nano-WO 3 -C composite powder obtained in step (1) in a vacuum tube sintering furnace, evacuate to 1 ⁇ 10 -3 Pa, heat up to 1150°C at a heating rate of 10°C/min, and keep it warm 2h, make graphite and WO 3 fully react, and obtain pure nano-WC powder by XRD analysis.
  • step (3) The nano WC powder obtained in step (2) and Co are proportioned according to the composition of WC-10Co, and 0.2% of the total mass of the WC powder and Co is added, and the ball milled with plasma for 3 hours, and finally a uniformly mixed
  • the WC-Co composite powder is finally pressed and vacuum sintered at 1400°C for 1 hour to obtain the ultrafine grained WC-10Co cemented carbide of the present invention, wherein the pressing force is 120 MPa, and the vacuum sintering pressure is 1 ⁇ 10 -3 Pa.
  • the WC-10Co cemented carbide prepared in this embodiment was analyzed by XRD, and its phase composition was WC and Co, and its density was 98.5%.
  • the electrode rod uses ceramic as a dielectric barrier layer and has a thickness of 5 mm, a ball-to-material ratio of 50:1, a ball milling speed of 960 rpm, and a ball milling time of 6 hours to obtain nano-WO 3 -C composite powder.
  • step (2) Place the nano-WO 3 -C composite powder obtained in step (1) in a vacuum tube sintering furnace, evacuate to 1 ⁇ 10 -3 Pa, heat up to 1150°C at a heating rate of 10°C/min, and keep it warm After 1h, the graphite and WO3 were fully reacted, and after XRD analysis, the nano-WC powder with only WC phase was obtained.
  • step (3) The nano WC powder prepared in step (2) and Co are proportioned according to the composition of WC-8Co, and 0.25% of the total mass of WC powder and Co is added, and the plasma ball mill is used for 3 hours, and finally a uniform mixture is obtained
  • the WC-Co composite powder is finally pressed and sintered at low pressure.
  • the sintering temperature is also 1350°C and the holding time is 1h to obtain the ultra-fine grained WC-8Co cemented carbide.
  • the pressing force is 150MPa, and the low pressure sintering pressure is 4MPa.
  • the WC-8Co cemented carbide prepared in this embodiment was analyzed by XRD, and its phase composition was WC and Co, and its density was 99.0%.
  • the electrode rod uses ceramic as a dielectric barrier layer and has a thickness of 4 mm, a ball-to-material ratio of 50:1, a ball milling speed of 960 rpm, and a ball milling time of 10 hours to obtain nano-WO 3 -C composite powder.
  • step (2) Place the nano-WO 3 -C composite powder obtained in step (1) in a vacuum tube sintering furnace, evacuate to 1 ⁇ 10 -3 Pa, heat up to 1150°C at a heating rate of 10°C/min, and keep it warm 1h, make graphite and WO 3 fully react, and obtain pure nano-WC powder by XRD analysis.
  • step (3) The nano WC powder obtained in step (2) and Co are proportioned according to the composition of WC-8Co, and 0.25% of the total mass of WC powder and Co is added, and 2% of paraffin wax is added as a forming agent, and plasma After ball milling for 1 hour, a uniformly mixed WC-Co composite powder is finally obtained. Finally, it is pressed and sintered at a low pressure at a sintering temperature of 1390°C and held for 1 hour to obtain an ultra-fine grained WC-8Co cemented carbide.
  • the pressing force is 150MPa
  • the low pressure sintering pressure is 5MPa.
  • the grain size of WC in the WC-8Co cemented carbide prepared in this embodiment is 450-550 nm.
  • the phase composition is WC and Co
  • the density is 99.4%
  • the bending strength is 2610 MPa.
  • the electrode rod uses ceramic as a dielectric barrier layer and has a thickness of 4 mm, a ball-to-material ratio of 50:1, a ball milling speed of 960 rpm, and a ball milling time of 3 hours to obtain nano-WO 3 -C composite powder.
  • step (2) Place the nano-WO 3 -C composite powder obtained in step (1) in a vacuum tube sintering furnace, evacuate to 1 ⁇ 10 -3 Pa, heat up to 1050°C at a temperature rise rate of 10°C/min, and keep warm 1h, make graphite and WO 3 fully react to obtain nano WC powder with an average particle size of 110nm.
  • step (3) The nano WC powder obtained in step (2) and Co are proportioned according to the composition of WC-8Co, and 0.25% of the total mass of WC powder and Co is added, and 2% of paraffin wax is added as a forming agent, and plasma After ball milling for 1 hour, a uniformly mixed WC-Co composite powder is finally obtained. Finally, it is pressed and sintered at a low pressure at a sintering temperature of 1410°C and held for 1 hour to obtain the ultra-fine grained WC-8Co cemented carbide.
  • the pressing force is 150MPa
  • the low pressure sintering pressure is 5MPa.
  • the WC grain size of the WC-8Co cemented carbide prepared in this embodiment is 350-450 nm.
  • the phase composition is WC and Co
  • the density is 99.4%
  • the bending strength is 2821 MPa.
  • Figure 4 is a DSC-TG chart of the nano-WO 3 -C composite powder prepared in step (1) in Example 1 of the present invention. It can be concluded from Fig. 4 that the WO 3 -C composite powder obtained by plasma ball milling has high activity, and its in-situ reduction initiation temperature drops to 851°C.
  • Fig. 6 is an SEM image of the nano-WC powder prepared in step (2) in Example 2 of the present invention. It can be concluded from Figure 6 that the in-situ synthesized WC particles are fine and uniformly dispersed, and have a high degree of sphericity.
  • Figure 10 is the WC grain size distribution diagram in the WC-8Co cemented carbide prepared in step (3) in Example 4 of the present invention. It can be obtained from Figure 10 that the WC-8Co cemented carbide prepared by the in-situ reduction method The WC grains in the WC are very small, and the WC grain size is between 450 and 550 nm.

Abstract

Disclosed is a method for preparing a superfine grain WC-Co hard alloy by means of plasma ball milling. The method comprises using WO3 and graphite as raw materials, pre-treating same by means of plasma discharge ball milling, then placing same into a vacuum sintering furnace for in situ synthesis of a high-purity nano WC powder, and finally mixing same with Co and ball milling same, and then pressing and sintering same to prepare the superfine grain WC-Co hard alloy. With plasma ball milling, the ball milling time is shortened, and the activity of the powder is greatly improved, and the in situ synthesis and sintering temperatures of a WC phase are significantly reduced. The method for preparing a superfine grain hard alloy has a low cost, a low energy consumption, a short procedure, and a simple and convenient process. The prepared hard alloy has a fine WC grain size and excellent mechanical properties.

Description

一种等离子体球磨制备超细晶WC-Co硬质合金的方法Method for preparing ultrafine WC-Co cemented carbide by plasma ball milling 技术领域Technical field
本发明属于硬质合金与粉末冶金技术领域，具体涉及一种等离子体球磨制备超细晶WC-Co硬质合金的方法。The invention belongs to the technical field of cemented carbide and powder metallurgy, and in particular relates to a method for preparing ultrafine-crystalline WC-Co cemented carbide by plasma ball milling.
背景技术Background technique
WC-Co硬质合金作为发展最早且最为成熟的一种硬质合金，因其具有较高的硬度、耐磨性及横向断裂强度，被广泛应用在切削、模具、耐磨零部件及矿山工具等领域。工业上常采用W、C为原料，先通过1400℃的高温碳化合成WC，再与Co混合进行长时间球磨制备WC-Co复合粉末，然后进行造粒，压制，脱蜡，最后进行高温烧结，经历了两次高温处理，WC长大严重，难以制备超细晶硬质合金。为了降低原料成本和制备超细晶的硬质合金，工业上也常采用廉价的WO 3代替W单质为原料与石墨在高温下进行原位合成WC的反应，为了实现WC相的高纯度完全合成，通常在反应前，WO 3和石墨混合粉末需进行球磨来活化粉末，但是传统的球磨方法球磨效率太低，球磨时间长，球磨过程中粉末污染严重。中国专利CN101624673A公布了一种制备高性能WC-Co硬质合金的工业化制备方法，以钨钴氧化物和炭黑为原料，经普通球磨预处理再原位合成、压制、烧结制备出硬质合金。该方法采用普通球磨效率低，球磨后的粉末活性不高，所需原位合成温度高，最终使得合成的WC粉末粒径粗大，只有在添加晶粒长大抑制剂基础上，其平均粒径才达到210nm。虽然目前应用新型烧结技术如微波烧结、等离子体烧结即使普通球磨预处理也可以在较低的烧结温度下制备超细晶WC硬质合金，但是这些新型的烧结设备与目前生产设备相比，价格相当昂贵，且一次制备的材料数量非常有限，很难制备大尺寸的硬质合金块体，因而针对这些设备研发出来的方法只能在实验室范围内应用，无法推广到实际工业生产中。利用原位合成+低压烧结/真空烧结依然是工业常用方法。 WC-Co cemented carbide is the earliest and most mature cemented carbide. Because of its high hardness, wear resistance and transverse fracture strength, it is widely used in cutting, molds, wear-resistant parts and mining tools. And other fields. In industry, W and C are often used as raw materials. First, WC is synthesized through high temperature carbonization at 1400°C, and then mixed with Co for long-term ball milling to prepare WC-Co composite powder, then granulation, pressing, dewaxing, and finally high temperature sintering. After two high-temperature treatments, WC has grown severely and it is difficult to prepare ultra-fine-grained cemented carbide. In order to reduce the cost of raw materials and prepare ultra-fine-grained cemented carbide, the industry often uses cheap WO 3 instead of W as the raw material to synthesize WC in situ with graphite at high temperature, in order to achieve high purity and complete synthesis of WC phase Generally, before the reaction, the WO 3 and graphite mixed powder needs to be ball milled to activate the powder, but the traditional ball milling method has too low ball milling efficiency, long ball milling time, and serious powder pollution during the ball milling process. Chinese patent CN101624673A discloses an industrialized preparation method for preparing high-performance WC-Co cemented carbide. Tungsten-cobalt oxide and carbon black are used as raw materials, and the cemented carbide is prepared by in-situ synthesis, pressing and sintering after ordinary ball milling. . This method uses ordinary ball milling with low efficiency, low activity of the powder after ball milling, and high in-situ synthesis temperature required. Finally, the particle size of the synthesized WC powder is coarse. Only on the basis of adding a grain growth inhibitor, the average particle size is Only reached 210nm. Although the current application of new sintering technologies such as microwave sintering and plasma sintering can produce ultra-fine WC cemented carbide at a lower sintering temperature even with ordinary ball milling pretreatment, these new sintering equipment is more expensive than current production equipment. It is quite expensive, and the amount of materials prepared at one time is very limited. It is difficult to prepare large-size cemented carbide blocks. Therefore, the methods developed for these equipment can only be applied in the laboratory and cannot be extended to actual industrial production. The use of in-situ synthesis + low pressure sintering/vacuum sintering is still a common method in the industry.
技术问题technical problem
提供一种等离子体球磨制备超细晶WC-Co硬质合金的方法，解决原位合成纳米WC粉末的温度以及后续烧结温度高的技术问题。A method for preparing ultrafine WC-Co cemented carbide by plasma ball milling is provided, which solves the technical problems of high temperature for in-situ synthesis of nano-WC powder and high subsequent sintering temperature.
技术解决方案Technical solutions
针对现有技术的不足，本发明的主要目的在于提供一种等离子体球磨制备超细晶WC-Co硬质合金的方法。本发明在非常短的球磨时间制备出高活性的WO 3-C复合粉末，可显著降低原位合成纳米WC粉末的温度以及后续烧结温度，制备出晶粒细小的超细晶WC-Co硬质合金。 In view of the shortcomings of the prior art, the main purpose of the present invention is to provide a method for preparing ultrafine WC-Co cemented carbide by plasma ball milling. The invention prepares highly active WO 3 -C composite powder in a very short ball milling time, can significantly reduce the temperature of in-situ synthesis of nano WC powder and the subsequent sintering temperature, and prepare ultrafine WC-Co hard with fine grains alloy.
本发明的技术方案为：以WO 3和石墨为原料，利用等离子体放电球磨预处理，然后放入真空烧结炉中原位合成高纯度纳米WC粉末，最后与Co混合球磨，压制，烧结制备出超细晶的WC-Co硬质合金。该方法球磨时间短，原位合成温度低，可实现快速原位制备超细晶WC-Co硬质合金，具有突出的工业应用价值。 The technical scheme of the present invention is: using WO 3 and graphite as raw materials, pretreatment by plasma discharge ball milling, and then putting it into a vacuum sintering furnace to synthesize high purity nano WC powder in situ, and finally mixing with Co, ball milling, pressing, and sintering to prepare super Fine-grained WC-Co cemented carbide. The method has short ball milling time and low in-situ synthesis temperature, can realize rapid in-situ preparation of ultra-fine grained WC-Co cemented carbide, and has outstanding industrial application value.
本发明的目的通过以下技术方案实现：The purpose of the present invention is achieved through the following technical solutions:
一种等离子体球磨制备超细晶WC-Co硬质合金的方法，包括以下步骤：A method for preparing ultrafine WC-Co cemented carbide by plasma ball milling includes the following steps:
（1）将WO 3和石墨加入到等离子体球磨机中，并加入无水乙醇作助磨剂进行球磨，制备得到WO 3-C复合粉末；将WO 3-C复合粉末加热，原位还原反应后，得到纳米WC粉末； (1) Add WO 3 and graphite to a plasma ball mill, and add anhydrous ethanol as a grinding aid for ball milling to prepare WO 3 -C composite powder; heat the WO 3 -C composite powder, and after in-situ reduction reaction , Get nano WC powder;
（2）取Co与步骤（1）制备得到的纳米WC粉末按照WC- X Co进行配比，X=6~12，加入补碳并再次进行等离子体球磨，制备得到纳米WC-Co复合粉末； (2) Take Co and the nano WC powder prepared in step (1) according to the ratio of WC- X Co, X=6~12, add carbon supplement and perform plasma ball milling again to prepare nano WC-Co composite powder;
（3）步骤（2）得到的纳米WC-Co复合粉末经压制、烧结得到所述超细晶WC-Co硬质合金。(3) The nano-WC-Co composite powder obtained in step (2) is pressed and sintered to obtain the ultra-fine grained WC-Co cemented carbide.
优选的，步骤（1）所述WO 3和石墨的质量份数比为80~85：15~20。 Preferably, the weight ratio of WO 3 and graphite in step (1) is 80-85:15-20.
优选的，步骤（1）所述无水乙醇的加入量为WO 3和石墨总质量的1~3wt%。 Preferably, the amount of the absolute ethanol added in step (1) is 1 to 3 wt% of the total mass of WO 3 and graphite.
优选的，步骤（1）所述等离子体球磨机的参数为：球料比为15 : 1 ~ 50 : 1，球磨时间为3 h~10 h，球磨机转速为960~1400rpm，等离子体放电气氛为5×10 3~1×10 5Pa，介质阻挡层介电常数为2~10，介质阻挡层厚度为3~5mm。 Preferably, the parameters of the plasma ball mill in step (1) are: the ball-to-material ratio is 15:1-50:1, the ball milling time is 3h-10h, the speed of the ball mill is 960-1400rpm, and the plasma discharge atmosphere is 5. ×10 3 ~1×10 5 Pa, the dielectric constant of the dielectric barrier is 2~10, and the thickness of the dielectric barrier is 3~5mm.
优选的，步骤（1）所述加热的温度为950~1150℃，所述加热的时间为1-2h，所述加热的压强为1×10 -3~1×10 -4Pa。 Preferably, the heating temperature in step (1) is 950 to 1150° C., the heating time is 1-2 h, and the heating pressure is 1×10 -3 to 1×10 -4 Pa.
优选的，步骤（1）所述WO 3的颗粒尺寸为5~10μm。 Preferably, the particle size of WO 3 in step (1) is 5-10 μm.
优选的，步骤（2）所述补碳的量为纳米WC粉末和Co总质量的0.2~0.3wt%。Preferably, the amount of carbon supplement in step (2) is 0.2-0.3 wt% of the total mass of nano-WC powder and Co.
优选的，步骤（2）所述Co的颗粒尺寸为30~50μm。Preferably, the particle size of Co in step (2) is 30-50 μm.
优选的，步骤（2）所述再次进行等离子体球磨的时间为1~3h。Preferably, the time for performing plasma ball milling again in step (2) is 1 to 3 hours.
优选的，步骤（3）所述压制的压力为100~150MPa。Preferably, the pressing pressure in step (3) is 100-150 MPa.
优选的，步骤（3）所述烧结的温度为1350~1410℃，所述烧结的时间为1~2h。Preferably, the sintering temperature in step (3) is 1350 to 1410° C., and the sintering time is 1 to 2 hours.
优选的，步骤（3）所述烧结为真空烧结或低压烧结，更优选的，所述低压烧结的压强为4~5Mpa，所述的真空烧结的压强为1×10 -3~5×10 -3Pa。 Preferably, the step (3) vacuum sintering or sintering the low pressure sintering, and more preferably, the low pressure sintering is 4 ~ 5Mpa, the pressure of the vacuum sintering 1 × 10 -3 ~ 5 × 10 - 3 Pa.
有益效果Beneficial effect
与现有技术相比，本发明具有以下优点和有益效果：Compared with the prior art, the present invention has the following advantages and beneficial effects:
（1）首先应用化学热力学模型，计算了WO 3和石墨在真空状态下发生原位还原碳化反应的吉布斯自由能的变化，从理论上分析了原位反应发生的可行性，并根据WO 3和石墨反应方程式计算出理论配碳量范围，并以此指导该专利工艺参数的制定，可以获得高纯度纳米晶WC粉末。 (1) First, the chemical thermodynamic model was used to calculate the Gibbs free energy change of the in-situ reduction and carbonization reaction of WO 3 and graphite under vacuum. The feasibility of the in-situ reaction was theoretically analyzed, and according to WO 3 Calculate the theoretical carbon content range with the graphite reaction equation, and use this to guide the formulation of the patented process parameters to obtain high-purity nanocrystalline WC powder.
（2）本发明以廉价WO 3替代昂贵的单质W为原料，可有效降低生产成本，同时利用石墨与WO 3的原位反应特性可以合成比表面积高，活性高的纳米级颗粒状WC粉末，为实现制备超细晶WC硬质合金做好准备。 (2) The present invention uses cheap WO 3 instead of expensive elemental W as raw material, which can effectively reduce production costs. At the same time, it can synthesize nano-scale granular WC powder with high specific surface area and high activity by using the in-situ reaction characteristics of graphite and WO 3 , To prepare for the preparation of ultra-fine grained WC cemented carbide.
（3）本发明采用等离子体放电球磨，可以显著的提高球磨效率，缩短球磨时间，避免球磨所带来的杂质污染，由于等离子体放电球磨结合了机械能和等离子场能，等离子离化电子吸附粉体表面，并且在等离子体作用下石墨容易形成超片状结构，增加WO 3/C的反应界面面积，因而可以显著细化和活化WO 3和石墨复合粉末，有效地降低WO 3和石墨原位反应温度，避免WC在高温下的长大，从而合成纳米WC粉末。 (3) The present invention adopts plasma discharge ball milling, which can significantly improve ball milling efficiency, shorten ball milling time, and avoid impurity pollution caused by ball milling. Because plasma discharge ball milling combines mechanical energy and plasma field energy, plasma ionization electron adsorption powder On the surface of the body, graphite easily forms a super-flaky structure under the action of plasma, which increases the reaction interface area of WO 3 /C, which can significantly refine and activate WO 3 and graphite composite powders, effectively reducing WO 3 and graphite in situ The reaction temperature avoids the growth of WC at high temperatures, thereby synthesizing nano-WC powder.
（4）本发明采用低压烧结技术可以有效地促进粉体致密化过程，在较低的烧结温度和保温时间就可以制备接近全致密的块体硬质合金，因此，可以有效地避免WC晶粒在烧结温度过高或保温时间过长而严重长大。其最终的硬质合金WC晶粒尺寸仅为350~450nm，属于超细晶范围。(4) The low-pressure sintering technology used in the present invention can effectively promote the powder densification process. At a lower sintering temperature and holding time, a nearly fully dense bulk cemented carbide can be prepared. Therefore, WC grains can be effectively avoided. The sintering temperature is too high or the holding time is too long and it grows up seriously. The final grain size of cemented carbide WC is only 350~450nm, which belongs to the ultrafine grain range.
附图说明Description of the drawings
图1为本发明制备方法的工艺流程图。Figure 1 is a process flow diagram of the preparation method of the present invention.
图2为本发明的实施1中步骤（1）制备的WO 3-C的复合粉末的SEM图。 Fig. 2 is an SEM image of the WO 3 -C composite powder prepared in step (1) in embodiment 1 of the present invention.
图3为本发明的实施例3中步骤（1）制备的WO 3-C的复合粉末的XRD图。 Figure 3 is an XRD pattern of the WO 3 -C composite powder prepared in step (1) in Example 3 of the present invention.
图4为本发明的实施例1中步骤（1）制备的纳米WO 3-C复合粉末的DSC-TG图。 Figure 4 is a DSC-TG chart of the nano-WO 3 -C composite powder prepared in step (1) in Example 1 of the present invention.
图5为本发明的实施例2中步骤（2）制得的纳米WC粉末的XRD图。Fig. 5 is an XRD pattern of the nano-WC powder prepared in step (2) in Example 2 of the present invention.
图6为本发明的实施例2中步骤（2）制得的纳米WC粉末的SEM图。Fig. 6 is an SEM image of the nano-WC powder prepared in step (2) in Example 2 of the present invention.
图7为本发明的实施例2中步骤（3）制得的WC-10Co硬质合金的XRD图。Fig. 7 is an XRD pattern of the WC-10Co cemented carbide prepared in step (3) in Example 2 of the present invention.
图8为本发明的实施例4中步骤（3）制得的WC-8Co硬质合金的SEM图。FIG. 8 is an SEM image of the WC-8Co cemented carbide prepared in step (3) in Example 4 of the present invention.
图9为本发明的实施例4中步骤（3）制得的WC-8Co硬质合金抛光后的SEM图。FIG. 9 is an SEM image of the WC-8Co cemented carbide prepared in step (3) in Example 4 of the present invention after polishing.
图10为本发明的实施例4中步骤（3）制得的WC-8Co硬质合金中WC晶粒尺寸分布图。Fig. 10 is a distribution diagram of the WC grain size in the WC-8Co cemented carbide prepared in step (3) in Example 4 of the present invention.
本发明的实施方式Embodiments of the invention
下面结合实施例，对本发明作进一步地详细说明，但本发明的实施方式不限于此。Hereinafter, the present invention will be further described in detail with reference to the examples, but the embodiments of the present invention are not limited thereto.
本实施例的氩气氛围等离子体放电球磨法中，所述磨球为硬质合金磨球，罐体为硬质合金内衬不锈钢罐，磨球总体积占球磨罐容积的30%~50%。其磨球的具体直径尺寸及所占总磨球的数量比例如下: 22mm的磨球占15%，15mm的磨球占25%， 10mm的磨球占30%，6mm的磨球占30%。所述球磨粉末体积占磨球之间空隙的40%，球磨球料比为15:1~50:1，放电电压15KV，放电电流1.5A，激振块采用双振幅5mm，球磨转速960rpm~1400rpm。In the argon atmosphere plasma discharge ball milling method of this embodiment, the grinding balls are cemented carbide grinding balls, the tank body is a cemented carbide lining stainless steel tank, and the total volume of the grinding balls accounts for 30%-50% of the volume of the ball milling tank. . The specific diameter and size of the grinding balls and the proportion of the total number of grinding balls are as follows: 22mm grinding balls account for 15%, 15mm grinding balls account for 25%, 10mm grinding balls account for 30%, and 6mm grinding balls account for 30%. The volume of the ball milling powder occupies 40% of the gap between the grinding balls, the ball-grinding material ratio is 15:1-50:1, the discharge voltage is 15KV, and the discharge current is 1.5A. The vibration block adopts a double amplitude of 5mm and the ball milling speed is 960rpm~1400rpm. .
实施例1Example 1
WC-12Co硬质合金WC-12Co cemented carbide
（1）将85g的WO 3配15g的石墨的混合粉末放入到1个大气压下氩气氛围等离子体放电辅助球磨机中对其进行等离子放电球磨，并加入占WO 3和石墨总质量1wt%的无水乙醇作助磨剂。电极棒以塑料王为介质阻挡层且厚度为3mm，球料比为15:1，球磨转速960rpm，球磨时间6h，得到高活性纳米WO 3-C的复合粉末。 (1) Put the mixed powder of 85g WO 3 and 15g graphite into a plasma discharge auxiliary ball mill under an argon atmosphere at 1 atmospheric pressure for plasma discharge ball milling, and add 1wt% of the total weight of WO 3 and graphite Absolute ethanol is used as a grinding aid. The electrode rod uses plastic king as the dielectric barrier layer and has a thickness of 3mm, a ball-to-material ratio of 15:1, a ball milling speed of 960rpm, and a ball milling time of 6h to obtain a highly active nano-WO 3 -C composite powder.
（2）将步骤（1）得到的纳米WO 3-C的复合粉末再置于真空管式烧结炉中，抽真空至1×10 -3Pa，在10℃/min的升温速率下升温至950℃，保温1h，使石墨和WO 3充分反应，获得纳米WC粉末。 (2) Place the nano-WO 3 -C composite powder obtained in step (1) in a vacuum tube sintering furnace, evacuate to 1×10 -3 Pa, and heat up to 950°C at a heating rate of 10°C/min ，Hold for 1h to make graphite and WO 3 fully react to obtain nano-WC powder.
（3）将步骤（2）得到的纳米WC粉末再与Co按WC-12Co的成分进行配比，并加入占WC粉末和Co总质量0.3%的石墨，进行等离子体球磨3h，最后得到均匀混合的WC-Co复合粉末，最后经压制，1350℃下真空烧结1h，得到本发明所述的超细晶WC-12Co硬质合金。其中压制力为100MPa，真空烧结气压为1×10 -3Pa。 (3) The nano-WC powder obtained in step (2) is then mixed with Co according to the composition of WC-12Co, and 0.3% of the total mass of WC powder and Co is added, and plasma ball milling is performed for 3 hours, and finally a uniform mixture is obtained The WC-Co composite powder is finally pressed and vacuum sintered at 1350°C for 1 hour to obtain the ultrafine crystalline WC-12Co cemented carbide according to the present invention. The pressing force is 100MPa, and the vacuum sintering pressure is 1×10 -3 Pa.
该实施例制备得到的WC-12Co硬质合金中的WC晶粒尺寸为650~750nm，经XRD分析，其物相组成为WC和Co，致密度为98.2%。The WC grain size in the WC-12Co cemented carbide prepared in this embodiment is 650-750 nm. According to XRD analysis, the phase composition is WC and Co, and the density is 98.2%.
实施例2Example 2
WC-10Co硬质合金WC-10Co cemented carbide
（1）将80g的WO 3配20g的石墨的混合粉末置于搅拌机中对粉末进行均匀化搅拌，时间为3h，然后将得到的均匀化后的WO 3和石墨粉末放入到0.05个大气压的氩气氛围等离子体放电辅助球磨机中对其进行等离子放电球磨，并加入占WO 3和石墨总质量1.5wt%的无水乙醇作助磨剂。电极棒以塑料王为介质阻挡层且厚度为4mm，球料比为30:1，球磨转速1400rpm，球磨时间6h，得到纳米WO 3-C复合粉末。 (1) Put the mixed powder of 80g WO 3 and 20g graphite in a mixer to homogenize the powder for 3 hours, and then put the homogenized WO 3 and graphite powder to 0.05 atmospheres Plasma discharge ball milling was carried out in an argon atmosphere plasma discharge auxiliary ball mill, and 1.5wt% of the total weight of WO 3 and graphite was added as a grinding aid. The electrode rod uses plastic king as the dielectric barrier layer and has a thickness of 4 mm, a ball-to-material ratio of 30:1, a ball milling speed of 1400 rpm, and a ball milling time of 6 hours to obtain nano-WO 3 -C composite powder.
（2）将步骤（1）得到的纳米WO 3-C复合粉末置于真空管式烧结炉中，抽真空至1×10 -3Pa，在10℃/min的升温速率下升温至1150℃，保温2h，使石墨和WO 3充分反应，经XRD分析，获得纯净的纳米WC粉末。 (2) Place the nano-WO 3 -C composite powder obtained in step (1) in a vacuum tube sintering furnace, evacuate to 1×10 -3 Pa, heat up to 1150°C at a heating rate of 10°C/min, and keep it warm 2h, make graphite and WO 3 fully react, and obtain pure nano-WC powder by XRD analysis.
（3）将步骤（2）获得的纳米WC粉末与Co按WC-10Co的成分进行配比，并加入占WC粉末和Co总质量0.2%的石墨，并用等离子体球磨3h，最后得到均匀混合的WC-Co复合粉末，最后经压制，1400℃下真空烧结1h得到本发明所述的超细晶WC-10Co硬质合金，其中压制力为120MPa，真空烧结气压为1×10 -3Pa。 (3) The nano WC powder obtained in step (2) and Co are proportioned according to the composition of WC-10Co, and 0.2% of the total mass of the WC powder and Co is added, and the ball milled with plasma for 3 hours, and finally a uniformly mixed The WC-Co composite powder is finally pressed and vacuum sintered at 1400°C for 1 hour to obtain the ultrafine grained WC-10Co cemented carbide of the present invention, wherein the pressing force is 120 MPa, and the vacuum sintering pressure is 1×10 -3 Pa.
该实施例制备得到的WC-10Co硬质合金经XRD分析，其物相组成为WC和Co，致密度为98.5%。The WC-10Co cemented carbide prepared in this embodiment was analyzed by XRD, and its phase composition was WC and Co, and its density was 98.5%.
实施例3Example 3
WC-8Co硬质合金WC-8Co cemented carbide
（1）将82g的WO 3配18g的石墨的混合粉末放入到1个大气压的氩气氛围等离子体放电辅助球磨机中对其进行等离子放电球磨，并加入占WO 3和石墨总质量2wt%的无水乙醇作助磨剂。电极棒以陶瓷为介质阻挡层且厚度为5mm，球料比为50:1，球磨转速960rpm，球磨时间6h，得到纳米WO 3-C的复合粉末。 (1) Put the mixed powder of 82g WO 3 and 18g graphite into a plasma discharge auxiliary ball mill under 1 atmosphere of argon atmosphere to perform plasma discharge ball milling, and add 2wt% of WO 3 and graphite total mass Absolute ethanol is used as a grinding aid. The electrode rod uses ceramic as a dielectric barrier layer and has a thickness of 5 mm, a ball-to-material ratio of 50:1, a ball milling speed of 960 rpm, and a ball milling time of 6 hours to obtain nano-WO 3 -C composite powder.
（2）将步骤（1）得到的纳米WO 3-C复合粉末置于真空管式烧结炉中，抽真空至1×10 -3Pa，在10℃/min的升温速率下升温至1150℃，保温1h，使石墨和WO3充分反应，经XRD分析，获得物相仅有WC的纳米WC粉末。 (2) Place the nano-WO 3 -C composite powder obtained in step (1) in a vacuum tube sintering furnace, evacuate to 1×10 -3 Pa, heat up to 1150°C at a heating rate of 10°C/min, and keep it warm After 1h, the graphite and WO3 were fully reacted, and after XRD analysis, the nano-WC powder with only WC phase was obtained.
（3）将步骤（2）制得的纳米WC粉末与Co按WC-8Co的成分进行配比，并加入占WC粉末和Co总质量0.25%的石墨，并用等离子体球磨3h，最后得到均匀混合的WC-Co复合粉末，最后经压制，低压烧结，烧结温度同样为1350℃，保温1h，得到超细晶WC-8Co硬质合金。其中压制力为150MPa，低压烧结气压为4MPa。(3) The nano WC powder prepared in step (2) and Co are proportioned according to the composition of WC-8Co, and 0.25% of the total mass of WC powder and Co is added, and the plasma ball mill is used for 3 hours, and finally a uniform mixture is obtained The WC-Co composite powder is finally pressed and sintered at low pressure. The sintering temperature is also 1350℃ and the holding time is 1h to obtain the ultra-fine grained WC-8Co cemented carbide. The pressing force is 150MPa, and the low pressure sintering pressure is 4MPa.
该实施例制备得到的WC-8Co硬质合金经XRD分析，其物相组成为WC和Co，致密度为99.0%。The WC-8Co cemented carbide prepared in this embodiment was analyzed by XRD, and its phase composition was WC and Co, and its density was 99.0%.
实施例4Example 4
WC-8Co硬质合金WC-8Co cemented carbide
（1）将82g的WO 3配18g的石墨的混合粉末放入到1个大气压的氩气氛围等离子体放电辅助球磨机中对其进行等离子放电球磨，并加入占WO 3和石墨总质量2wt%的无水乙醇作助磨剂。电极棒以陶瓷为介质阻挡层且厚度为4mm，球料比为50:1，球磨转速960rpm，球磨时间10h，得到纳米WO 3-C的复合粉末。 (1) Put the mixed powder of 82g WO 3 and 18g graphite into a plasma discharge auxiliary ball mill under 1 atmosphere of argon atmosphere to perform plasma discharge ball milling, and add 2wt% of WO 3 and graphite total mass Absolute ethanol is used as a grinding aid. The electrode rod uses ceramic as a dielectric barrier layer and has a thickness of 4 mm, a ball-to-material ratio of 50:1, a ball milling speed of 960 rpm, and a ball milling time of 10 hours to obtain nano-WO 3 -C composite powder.
（2）将步骤（1）得到的纳米WO 3-C复合粉末置于真空管式烧结炉中，抽真空至1×10 -3Pa，在10℃/min的升温速率下升温至1150℃，保温1h，使石墨和WO 3充分反应，经XRD分析，获得纯净的纳米WC粉末。 (2) Place the nano-WO 3 -C composite powder obtained in step (1) in a vacuum tube sintering furnace, evacuate to 1×10 -3 Pa, heat up to 1150°C at a heating rate of 10°C/min, and keep it warm 1h, make graphite and WO 3 fully react, and obtain pure nano-WC powder by XRD analysis.
（3）将步骤（2）获得的纳米WC粉末与Co按WC-8Co的成分进行配比，并加入占WC粉末和Co总质量0.25%的石墨并加入2%的石蜡做成型剂，并用等离子体球磨1h，最后得到均匀混合的WC-Co复合粉末，最后经压制，低压烧结，烧结温度为1390℃，保温1h，得到超细晶WC-8Co硬质合金。其中压制力为150MPa，低压烧结气压为5MPa。(3) The nano WC powder obtained in step (2) and Co are proportioned according to the composition of WC-8Co, and 0.25% of the total mass of WC powder and Co is added, and 2% of paraffin wax is added as a forming agent, and plasma After ball milling for 1 hour, a uniformly mixed WC-Co composite powder is finally obtained. Finally, it is pressed and sintered at a low pressure at a sintering temperature of 1390°C and held for 1 hour to obtain an ultra-fine grained WC-8Co cemented carbide. The pressing force is 150MPa, and the low pressure sintering pressure is 5MPa.
该实施例制备得到的WC-8Co硬质合金中的WC的晶粒尺寸为450~550nm，经XRD分析，其物相组成为WC和Co，致密度为99.4%，抗弯强度为2610MPa。The grain size of WC in the WC-8Co cemented carbide prepared in this embodiment is 450-550 nm. According to XRD analysis, the phase composition is WC and Co, the density is 99.4%, and the bending strength is 2610 MPa.
实施例5Example 5
WC-8Co硬质合金WC-8Co cemented carbide
（1）将82g的WO 3配18g的石墨的混合粉末放入到1个大气压的氩气氛围等离子体放电辅助球磨机中对其进行等离子放电球磨，并加入占WO 3和石墨总质量3wt%的无水乙醇作助磨剂。电极棒以陶瓷为介质阻挡层且厚度为4mm，球料比为50:1，球磨转速960rpm，球磨时间3h，得到纳米WO 3-C的复合粉末。 (1) Put the mixed powder of 82g WO 3 and 18g graphite into a plasma discharge auxiliary ball mill under 1 atmosphere of argon atmosphere to perform plasma discharge ball milling, and add 3wt% of WO 3 and graphite total mass Absolute ethanol is used as a grinding aid. The electrode rod uses ceramic as a dielectric barrier layer and has a thickness of 4 mm, a ball-to-material ratio of 50:1, a ball milling speed of 960 rpm, and a ball milling time of 3 hours to obtain nano-WO 3 -C composite powder.
（2）将步骤（1）得到的纳米WO 3-C复合粉末置于真空管式烧结炉中，抽真空至1×10 -3Pa，在10℃/min的升温速率下升温至1050℃，保温1h，使石墨和WO 3充分反应，获得平均粒径为110nm的纳米WC粉末。 (2) Place the nano-WO 3 -C composite powder obtained in step (1) in a vacuum tube sintering furnace, evacuate to 1×10 -3 Pa, heat up to 1050°C at a temperature rise rate of 10°C/min, and keep warm 1h, make graphite and WO 3 fully react to obtain nano WC powder with an average particle size of 110nm.
（3）将步骤（2）获得的纳米WC粉末与Co按WC-8Co的成分进行配比，并加入占WC粉末和Co总质量0.25%的石墨并加入2%的石蜡做成型剂，并用等离子体球磨1h，最后得到均匀混合的WC-Co复合粉末,最后经压制，低压烧结，烧结温度为1410℃，保温1h，得到本超细晶WC-8Co硬质合金。其中压制力为150MPa，低压烧结气压为5MPa。(3) The nano WC powder obtained in step (2) and Co are proportioned according to the composition of WC-8Co, and 0.25% of the total mass of WC powder and Co is added, and 2% of paraffin wax is added as a forming agent, and plasma After ball milling for 1 hour, a uniformly mixed WC-Co composite powder is finally obtained. Finally, it is pressed and sintered at a low pressure at a sintering temperature of 1410°C and held for 1 hour to obtain the ultra-fine grained WC-8Co cemented carbide. The pressing force is 150MPa, and the low pressure sintering pressure is 5MPa.
该实施例制备得到的WC-8Co硬质合金的中的WC晶粒尺寸为350~450nm，经XRD分析，其物相组成为WC和Co，致密度为99.4%，抗弯强度为2821MPa。The WC grain size of the WC-8Co cemented carbide prepared in this embodiment is 350-450 nm. According to XRD analysis, the phase composition is WC and Co, the density is 99.4%, and the bending strength is 2821 MPa.
图4为本发明的实施例1中步骤（1）制备的纳米WO 3-C复合粉末的DSC-TG图。由图4可以得出，通过等离子体球磨获得WO 3-C复合粉末具有高活性，其原位还原起始温度降为851℃。 Figure 4 is a DSC-TG chart of the nano-WO 3 -C composite powder prepared in step (1) in Example 1 of the present invention. It can be concluded from Fig. 4 that the WO 3 -C composite powder obtained by plasma ball milling has high activity, and its in-situ reduction initiation temperature drops to 851°C.
图6为本发明的实施例2中步骤（2）制得的纳米WC粉末的SEM图。由图6可以得出，原位合成的WC颗粒细小且均匀分散，球形度较高。Fig. 6 is an SEM image of the nano-WC powder prepared in step (2) in Example 2 of the present invention. It can be concluded from Figure 6 that the in-situ synthesized WC particles are fine and uniformly dispersed, and have a high degree of sphericity.
图10为本发明的实施例4中步骤（3）制得的WC-8Co硬质合金中WC晶粒尺寸分布图，由图10可以得出，原位还原法制备的WC-8Co硬质合金中的WC晶粒非常细小，其WC晶粒尺寸在450~550nm之间。Figure 10 is the WC grain size distribution diagram in the WC-8Co cemented carbide prepared in step (3) in Example 4 of the present invention. It can be obtained from Figure 10 that the WC-8Co cemented carbide prepared by the in-situ reduction method The WC grains in the WC are very small, and the WC grain size is between 450 and 550 nm.
上述实施例为本发明较佳的实施方式，但本发明的实施方式并不受上述实施例的限制，其它的任何未背离本发明的精神实质与原理下所作的改变、修饰、替代、组合、简化，均应为等效的置换方式，都包含在本发明的保护范围之内。The above-mentioned embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited by the above-mentioned embodiments, and any other changes, modifications, substitutions, combinations, etc. made without departing from the spirit and principle of the present invention Simplified, all should be equivalent replacement methods, and they are all included in the protection scope of the present invention.

Claims (10)

  1. 一种等离子体球磨制备超细晶WC-Co硬质合金的方法，其特征在于，包括以下步骤：A method for preparing ultrafine WC-Co cemented carbide by plasma ball milling is characterized in that it comprises the following steps:
    （1）将WO 3和石墨加入到等离子体球磨机中，加入无水乙醇进行球磨，制备得到WO 3-C复合粉末；将WO 3-C复合粉末加热，原位还原反应后，得到纳米WC粉末； (1) Add WO 3 and graphite to a plasma ball mill, add anhydrous ethanol for ball milling to prepare WO 3 -C composite powder; heat the WO 3 -C composite powder and reduce in situ to obtain nano-WC powder ；
    （2）取Co与步骤（1）制备得到的纳米WC粉末按照WC- X Co进行配比，X=6~12，加入补碳并再次进行等离子体球磨，制备得到纳米WC-Co复合粉末； (2) Take Co and the nano WC powder prepared in step (1) according to the ratio of WC- X Co, X=6~12, add carbon supplement and perform plasma ball milling again to prepare nano WC-Co composite powder;
    （3）步骤（2）得到的纳米WC-Co复合粉末经压制、烧结得到所述超细晶WC-Co硬质合金。(3) The nano-WC-Co composite powder obtained in step (2) is pressed and sintered to obtain the ultra-fine grained WC-Co cemented carbide.
  2. 根据权利要求1所述等离子体球磨制备超细晶WC-Co硬质合金的方法，其特征在于，步骤（1）所述WO 3和石墨的质量份数比为80~85：15~20。 The method for preparing ultra-fine-grained WC-Co cemented carbide by plasma ball milling according to claim 1, characterized in that, in step (1), the weight ratio of WO 3 and graphite is 80-85:15-20.
  3. 根据权利要求2所述等离子体球磨制备超细晶WC-Co硬质合金的方法，其特征在于，步骤（1）所述等离子体球磨机的参数为：球料比为15 : 1 ~ 50 : 1，球磨时间为3 h~10 h，球磨机转速为960~1400rpm，等离子体放电气氛为5×10 3~1×10 5Pa，介质阻挡层介电常数为2~10，介质阻挡层厚度为3~5mm。 The method for preparing ultra-fine-grained WC-Co cemented carbide by plasma ball milling according to claim 2, wherein the parameters of the plasma ball mill in step (1) are: the ball-to-battery ratio is 15:1-50:1 The ball milling time is 3 h~10 h, the speed of the ball mill is 960~1400rpm, the plasma discharge atmosphere is 5×10 3 ~1×10 5 Pa, the dielectric constant of the dielectric barrier layer is 2-10, and the thickness of the dielectric barrier layer is 3 ~5mm.
  4. 根据权利要求1~3任一项所述等离子体球磨制备超细晶WC-Co硬质合金的方法，其特征在于，步骤（1）所述加热的温度为950~1150℃，所述加热的时间为1~2h，所述加热的压强为1×10 -3~1×10 -4Pa。 The method for preparing ultrafine-grained WC-Co cemented carbide by plasma ball milling according to any one of claims 1 to 3, wherein the heating temperature in step (1) is 950~1150°C, and the heating The time is 1 to 2 hours, and the heating pressure is 1×10 -3 to 1×10 -4 Pa.
  5. 根据权利要求1~3任一项所述等离子体球磨制备超细晶WC-Co硬质合金的方法，其特征在于，步骤（1）所述WO 3的颗粒尺寸为5-10μm；步骤（2）所述Co的颗粒尺寸为30~50μm。 The method for preparing ultra-fine-grained WC-Co cemented carbide by plasma ball milling according to any one of claims 1 to 3, characterized in that the particle size of the WO 3 in step (1) is 5-10 μm; and step (2) ) The particle size of the Co is 30-50 μm.
  6. 根据权利要求1~3任一项所述等离子体球磨制备超细晶WC-Co硬质合金的方法，其特征在于，步骤（1）所述无水乙醇的加入量为WO 3和石墨总质量的1~3wt%。 The method for preparing ultra-fine-grained WC-Co cemented carbide by plasma ball milling according to any one of claims 1 to 3, characterized in that the adding amount of the absolute ethanol in step (1) is WO 3 and the total mass of graphite的1~3wt%.
  7. 根据权利要求1~3任一项所述等离子体球磨制备超细晶WC-Co硬质合金的方法，其特征在于，步骤（2）所述补碳的量为WC粉末和Co总质量的0.2~0.3wt%；步骤（2）所述再次进行等离子体球磨的时间为1~3h。The method for preparing ultra-fine grained WC-Co cemented carbide by plasma ball milling according to any one of claims 1 to 3, wherein the amount of carbon supplement in step (2) is 0.2 of the total mass of WC powder and Co. ~0.3wt%; the time for plasma ball milling in step (2) is 1~3h.
  8. 根据权利要求1~3任一项所述等离子体球磨制备超细晶WC-Co硬质合金的方法，其特征在于，步骤（3）所述烧结的温度为1350~1410℃，所述烧结的时间为1~2h。The method for preparing ultrafine-grained WC-Co cemented carbide by plasma ball milling according to any one of claims 1 to 3, wherein the sintering temperature in step (3) is 1350~1410°C, and the sintered The time is 1~2h.
  9. 根据权利要求1~3任一项所述等离子体球磨制备超细晶WC-Co硬质合金的方法，其特征在于，步骤（3）所述压制的压力为100~150MPa。The method for preparing ultrafine-grained WC-Co cemented carbide by plasma ball milling according to any one of claims 1 to 3, wherein the pressing pressure in step (3) is 100 to 150 MPa.
  10. 根据权利要求1~3任一项所述等离子体球磨制备超细晶WC-Co硬质合金的方法，其特征在于，步骤（3）所述烧结为真空烧结或低压烧结。The method for preparing ultrafine WC-Co cemented carbide by plasma ball milling according to any one of claims 1 to 3, wherein the sintering in step (3) is vacuum sintering or low pressure sintering.
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