阅读说明：本技术 一种高强韧WC-Co硬质合金的制备方法 (Preparation method of high-strength and high-toughness WC-Co hard alloy ) 是由 高阳 杨方 度鹏 高卡 孙德建 郭晓琴 张锐 于 2020-08-06 设计创作，主要内容包括：本发明属于硬质合金制备技术领域,公开一种高强韧WC-Co硬质合金的制备方法。配制混合粉料,然后球磨、干燥、过筛,装入石墨模具中预压成型；将所得样品连通石墨模具放入振动烧结炉中,炉内气氛为真空或惰性气氛,首先对样品施加30~50 MPa的恒定压力,同时升温至烧结温度1240~1300℃,当达到烧结温度时,将恒定压力切换为振动压力进行振动烧结,其中振动压力的平均值30~50 MPa、振动压力的振动幅度10~50 MPa、振动频率1~10 Hz、振动烧结0.25~1 h；待振动烧结结束后,将振动压力重新切换为恒定压力,加热停止,随炉冷却,当振动烧结炉炉内的温度降到600~1000℃时,卸去恒定压力,并继续随炉自然冷却到室温,制得高强韧WC-Co硬质合金。本发明制备的高强韧WC-Co硬质合金,硬度较传统方法提高240 MPa以上,断裂韧性提高9.5%以上。(The invention belongs to the technical field of hard alloy preparation, and discloses a preparation method of high-toughness WC-Co hard alloy. Preparing mixed powder, then ball-milling, drying, sieving, filling into a graphite die and prepressing for molding; putting the obtained sample into a vibration sintering furnace, wherein the atmosphere in the furnace is vacuum or inert atmosphere, firstly applying constant pressure of 30-50 MPa to the sample, simultaneously heating to the sintering temperature of 1240-1300 ℃, and when the sintering temperature is reached, switching the constant pressure into vibration pressure for vibration sintering, wherein the average value of the vibration pressure is 30-50 MPa, the vibration amplitude of the vibration pressure is 10-50 MPa, the vibration frequency is 1-10 Hz, and the vibration sintering is carried out for 0.25-1 h; and after the vibration sintering is finished, switching the vibration pressure to constant pressure again, stopping heating, cooling along with the furnace, removing the constant pressure when the temperature in the vibration sintering furnace is reduced to 600-1000 ℃, and naturally cooling to room temperature along with the furnace to obtain the high-strength and high-toughness WC-Co hard alloy. Compared with the traditional method, the hardness of the high-toughness WC-Co hard alloy prepared by the invention is improved by over 240 MPa, and the fracture toughness is improved by over 9.5 percent.)

1. A preparation method of high-strength and high-toughness WC-Co hard alloy is characterized by comprising the following steps:

(1) preparing mixed powder by using tungsten carbide powder and cobalt powder as raw materials, then carrying out ball milling, drying and sieving after ball milling, and filling the powder into a graphite mold for prepressing and molding;

(2) putting a sample obtained after the pre-pressing forming in the step (1) into a vibration sintering furnace through a graphite mold, wherein the atmosphere in the furnace is vacuum or inert atmosphere, firstly applying constant pressure of 30-50 MPa to the sample, simultaneously heating to the sintering temperature of 1240-1300 ℃, and when the sintering temperature is reached, switching the constant pressure into vibration pressure for vibration sintering, wherein the average value of the vibration pressure is 30-50 MPa, the vibration amplitude of the vibration pressure is 10-50 MPa, the vibration frequency is 1-10 Hz, and the vibration sintering is carried out for 0.25-1 h;

(3) and after the vibration sintering is finished, switching the vibration pressure to constant pressure again, stopping heating, cooling along with the furnace, removing the constant pressure when the temperature in the vibration sintering furnace is reduced to 600-1000 ℃, and naturally cooling to room temperature along with the furnace continuously to obtain the high-strength and high-toughness WC-Co hard alloy.

2. The method for preparing the high-toughness WC-Co hard alloy as recited in claim 1, wherein: in the step (1), the particle size of the tungsten carbide powder is 1-1.5 μm, and the particle size of the cobalt powder is 0.8-1.3 μm; in the mixed powder, the content of the tungsten carbide powder is 88-98 wt%, and the balance is cobalt powder.

3. The method for preparing the high-toughness WC-Co hard alloy as recited in claim 1, wherein: in the step (1), the pressure of the pre-pressing forming is 5-20 MPa.

4. The method for preparing the high-toughness WC-Co hard alloy as recited in claim 1, wherein: in the step (1), the ball milling speed is 120-150 rpm, the ball milling time is 15-24 hours, stainless steel balls with the diameter of 6-12 mm are added in the ball milling process, the mass ratio of ball materials is (3-5): 1, and 200-350 mL of absolute ethyl alcohol is added into every 1 kg of mixed powder as a ball milling medium.

5. The method for preparing the high-toughness WC-Co hard alloy as recited in claim 1, wherein: in the step (1), the drying is vacuum drying, the temperature of the vacuum drying is 40-60 ℃, and the time is 2-8 hours.

6. The method for preparing the high-toughness WC-Co hard alloy as recited in claim 1, wherein: in the step (1), sieving the mixture by a sieve of 60-100 meshes.

7. The method for preparing the high-toughness WC-Co hard alloy as recited in claim 1, wherein: in the step (2), the temperature is increased to the sintering temperature at the temperature increase speed of 2-8 ℃/min.

Technical Field

The invention belongs to the technical field of hard alloy preparation, and particularly relates to a preparation method of high-toughness WC-Co hard alloy.

Background

The WC-Co hard alloy has the characteristics of high hardness, high wear resistance, high corrosion resistance and the like, and is widely applied to the fields of cutting tools, mining and mining, wear-resistant parts, die manufacturing and the like. The WC-Co type hard alloy is the hard alloy material with the largest output and consumption at present. However, because the hardness and the toughness of the conventional WC-Co hard alloy are mutually contradictory, the two properties cannot be simultaneously improved, and the improvement of one property must be at the expense of the other property, so that the development of high-end application of the WC-Co hard alloy is greatly limited.

In order to solve the contradiction between the hardness and the toughness of the WC-Co hard alloy and prepare the hard alloy with high toughness, researchers carry out a great deal of research to find that the materials with high hardness and toughness can be obtained to a certain extent when the hard alloy with the gradient structure, the hard alloy with the double-crystal structure, the superfine/nano-crystal hard alloy and the hard alloy with the coating structure are prepared. However, the preparation methods are complicated in preparation process, complex in operation flow and high in production cost; the other method is to prepare the coating hard alloy, but the production process has strict requirements, huge equipment investment and higher production cost, and greatly limits the large-scale industrial application of the high-toughness WC-Co hard alloy.

Based on the above situation, in order to further improve the performance of the WC-Co hard alloy and expand the application of the WC-Co hard alloy in high-end industries, it is urgently needed to develop a new preparation method of a high-toughness WC-Co hard alloy, so that the hardness and fracture toughness of the alloy are improved, and meanwhile, the traditional production process is not increased, which is beneficial to large-scale industrial production.

Disclosure of Invention

In order to overcome the defects in the prior art, the invention aims to provide a preparation method of high-strength and high-toughness WC-Co hard alloy.

In order to achieve the purpose, the technical scheme adopted by the invention is as follows:

a preparation method of high-strength and high-toughness WC-Co hard alloy comprises the following steps:

(1) preparing mixed powder by using tungsten carbide powder and cobalt powder as raw materials, then carrying out ball milling, drying and sieving after ball milling, and filling the powder into a graphite mold for prepressing and molding;

(2) putting a sample obtained after the pre-pressing forming in the step (1) into a vibration sintering furnace through a graphite mold, wherein the atmosphere in the furnace is vacuum or inert atmosphere, firstly applying constant pressure of 30-50 MPa to the sample, simultaneously heating to the sintering temperature of 1240-1300 ℃, and when the sintering temperature is reached, switching the constant pressure into vibration pressure for vibration sintering, wherein the average value of the vibration pressure is 30-50 MPa, the vibration amplitude of the vibration pressure is 10-50 MPa, the vibration frequency is 1-10 Hz, and the vibration sintering is carried out for 0.25-1 h;

(3) and after the vibration sintering is finished, switching the vibration pressure to constant pressure again, stopping heating, cooling along with the furnace, removing the constant pressure when the temperature in the vibration sintering furnace is reduced to 600-1000 ℃, and naturally cooling to room temperature along with the furnace continuously to obtain the high-strength and high-toughness WC-Co hard alloy.

Preferably, in the step (1), the particle size of the tungsten carbide powder is 1-1.5 μm, and the particle size of the cobalt powder is 0.8-1.3 μm; in the mixed powder, the content of the tungsten carbide powder is 88-98 wt%, and the balance is cobalt powder.

Preferably, in the step (1), the pressure of the pre-pressing forming is 5-20 MPa.

Preferably, in the step (1), the ball milling rotation speed is 120-150 rpm, the ball milling time is 15-24 hours, stainless steel balls with the diameter of 6-12 mm are added in the ball milling process, the mass ratio of ball materials is (3-5): 1, and 200-350 mL of absolute ethyl alcohol is added into every 1 kg of mixed powder as a ball milling medium.

Preferably, in the step (1), the drying is vacuum drying, the temperature of the vacuum drying is 40-60 ℃, and the time is 2-8 h.

Preferably, in the step (1), the powder is sieved by a sieve of 60-100 meshes.

Preferably, in the step (2), the temperature is increased to the sintering temperature at a temperature increasing speed of 2-8 ℃/min.

Compared with the prior art, the invention has the beneficial effects that:

(1) only applying vibration pressure in the sintering process of the high-toughness WC-Co hard alloy, compared with the conventional high-toughness hard alloy, the method does not need additional working procedures, has simple process, is beneficial to large-scale production, and simultaneously reduces the production cost of the high-toughness hard alloy;

(2) the preparation method can obviously reduce the sintering temperature, shorten the sintering time, reduce the residual pores in the material, inhibit the growth of crystal grains and prepare the hard alloy material with high strength and high toughness;

(3) compared with the traditional process, the hardness of the prepared high-strength and high-toughness WC-Co hard alloy is improved by over 240 MPa, the fracture toughness is improved by over 9.5 percent, and the comprehensive performance of the developed high-strength and high-toughness hard alloy is superior to that of the traditional process.

Drawings

FIG. 1 is an SEM image of a WC-Co cemented carbide made in example 1.

FIG. 2 is an SEM image of a WC — Co cemented carbide made in example 2.

Fig. 3 is an SEM image of the WC — Co cemented carbide prepared in comparative example 1.

Fig. 4 is an SEM image of the WC — Co cemented carbide prepared in comparative example 2.

Detailed Description

The present invention will be further described with reference to the following specific examples. It should be understood that the following examples are illustrative only and are not intended to limit the scope of the present invention.

The vibratory sintering furnace in the following example was purchased from multi-field coupled experimental systems of all-readily available materials technologies, inc, and was model OPS-2020.