CN107199346A - A kind of industrialized process for preparing of nanometer of W/WC composite powder - Google Patents

Abstract

The invention relates to an industrial preparation method of nanometer W/WC composite powder, which belongs to the technical field of refractory metal and powder metallurgy. Using tungsten oxide, cobalt oxide and glucose as raw materials, the mass ratio of cobalt oxide: tungsten oxide: glucose is 1: (10-85): (4.5-43). The oxide is subjected to high-energy ball milling; then glucose powder and absolute ethanol are added for secondary ball milling; the reaction is carried out in a vacuum furnace, the vacuum degree in the furnace is less than 10Pa, firstly heated to 150-180°C and kept for 15-60min, and then heated to 350°C Heat at ~500°C for 2-4 hours, and finally raise the temperature to 850-1100°C for 2-5 hours. Finally, the nanocomposite powder in which the tungsten carbide powder is distributed on the tungsten powder matrix is obtained. The average particle size of the generated tungsten powder can reach less than tens of nanometers, and the particle size distribution of the powder is uniform.

Description

A kind of industrial preparation method of nanometer W/WC composite powder

technical field

The invention relates to an industrialized preparation method for rapidly preparing W/WC composite powder in which nanoscale W powder is used as a matrix and a small amount of WC powder is dispersedly distributed, and belongs to the technical field of refractory metals and powder metallurgy.

Background technique

Tungsten is widely used in industrial fields due to its high density, high melting point, low thermal expansion coefficient, excellent electrical and thermal conductivity, and good corrosion resistance. Composite materials based on tungsten or its carbides, such as: WC-Co cemented carbide, W-Ni-Fe high specific gravity alloy, W-Cu alloy, etc. have become indispensable and important materials in many high-tech fields, such as micro Electronic industry, fine chemical industry, surface technology, aerospace, etc. The properties of tungsten-based alloys are closely related to those of W powder. When the particle size of tungsten powder is reduced to ultra-fine and nano-scale, the tungsten-based alloy prepared by it shows good sintering characteristics, and the prepared bulk material has high toughness, compressive strength, thermal shock resistance and so on. However, the mass production technology of nano-tungsten powder in my country is still immature, while enterprises in a few foreign countries can produce nano-tungsten powder. Therefore, it is an extremely important research and development direction to break the situation that a small number of foreign manufacturers control the international nano-tungsten powder and related product markets, and to prepare nano-tungsten powder with independent intellectual property rights.

In addition, due to the high brittleness of metal tungsten, the overall strength and wear resistance are poor; and the stable carbide (WC) of tungsten has the advantages of high hardness, high wear resistance and high corrosion resistance. Therefore, in nano tungsten powder The W/WC composite powder formed by medium-dispersed nano-WC powder particles plays a key role in enhancing the mechanical properties of tungsten-based alloys at room temperature and high temperature, expanding engineering application fields, and improving the service life of important equipment.

Contents of the invention

The present invention aims at the technical problems in the current industrial production of nano-tungsten powder and related products, and provides a simple, easy-to-control, and highly operable industrial preparation method of nano-W/WC composite powder.

The method for preparing nano W/WC composite powder provided by the present invention is characterized in that it comprises the following steps:

(1) Using tungsten oxide, cobalt oxide and glucose as raw materials, the mass ratio of cobalt oxide: tungsten oxide: glucose is 1: (10-85): (4.5-43) for batching, first oxidize tungsten The material and cobalt oxide are subjected to high-energy ball milling, the mass ratio of balls to powder is 3:1-10:1, absolute ethanol is used as the grinding medium, the volume ratio of grinding medium to material is 1:1, and the speed of the ball mill is 100-500r/ min, ball milling time is 60~80h.

(2) Glucose powder is added to the mixed powder obtained in step (1), and anhydrous ethanol in an equal volume ratio to the glucose is added to carry out secondary ball milling, the ball milling speed is 50-80r/min, and the ball milling time is 10-20h.

(3) Put the powder obtained in step (2) in a vacuum furnace for reaction, the vacuum degree in the furnace is less than 10Pa, first heat to 150-180°C and keep it for 15-60min, then raise the temperature to 350-500°C and keep it for 2-4h, Finally, the temperature was raised to 850-1100°C for 2-5 hours.

Generally, the number of moles of carbon in glucose is greater than the number of moles of oxygen in tungsten oxides and cobalt oxides.

The process and principle of this method are as follows: using tungsten oxide, cobalt oxide and glucose powder as raw materials, the oxide powder particles are fully ball-milled to the nanometer level using a step-by-step ball milling process, and then glucose powder is added at a low speed for ball milling Mix to avoid decomposition of glucose during high-energy ball milling, and then place the mixed powder under vacuum conditions for in-situ reduction carbonization reaction. During the reaction process, it is firstly heated to the melting and decomposition temperature of glucose. Taking advantage of the high surface energy of nano-powders, glucose is coated spontaneously on the surface of nano-oxide particles after melting; in addition, after heat preservation at the decomposition temperature of glucose, the carbon source is evenly distributed in the Oxide powder particle surface. At the reductive carbonization temperature, the oxides of tungsten and cobalt are reduced to tungsten and cobalt, and with the help of the accelerated diffusion of cobalt, part of the tungsten is carbonized to form tungsten carbide, and finally the tungsten carbide powder is distributed on the tungsten powder matrix. Composite powder.

The purpose of the present invention is to provide a simple and easy-to-control method for preparing composite powder of tungsten carbide distributed on a nano-tungsten substrate, which is suitable for industrial production.

Features and advantages of the present invention are as follows:

At present, the industrial method of preparing tungsten powder is mainly to reduce tungsten oxide powder at high temperature by H ₂ , CH ₄ or Co and other gases. Great danger. Compared with these preparation methods, the present invention has the advantages that the average particle size of the generated tungsten powder can reach below tens of nanometers, and the particle size distribution of the powder is even; when the glucose reaches the decomposition temperature, carbon and water vapor are generated, and the product is safe and environmentally friendly. Utilizing the characteristic of self-melting of glucose at low temperature, the oxide is coated to effectively promote the reduction reaction of tungsten oxide. At the same time, with the help of cobalt on the promotion of tungsten carbide, a composite powder material in which nano-WC powder is dispersed in nano-tungsten powder can be produced at a relatively low temperature (<1000°C), and cobalt is formed in a small amount of W-Co-C ternary phase The form exists in the composite powder. In this method, the particle size of tungsten and tungsten carbide powder, their respective proportions, and the generation rate of tungsten carbide can be accurately regulated by designing the reaction temperature and time, the content of glucose and cobalt oxide in the raw material powder, etc.

Description of drawings

Fig. 1 is a morphological diagram of the powder obtained after ball milling and mixing raw materials in Example 1 of the present invention.

Fig. 2 is the topography diagram of the powder coated with glucose after ball milling and mixing the raw materials in Example 1 of the present invention.

Figure 3 is the morphology diagram and particle size distribution diagram of the W/WC composite powder prepared in Example 2 of the present invention, wherein, a is the microstructure morphology of the tungsten-based composite powder prepared in Example 2; b is the embodiment 2 The particle size distribution diagram of the prepared composite powder.

Fig. 4 is a phase analysis diagram of the tungsten-based composite powder prepared in Example 3 of the present invention.

detailed description

The following examples further illustrate the present invention, but the present invention is not limited to the following examples.

Example 1

Weigh 1 kg of WO ₃ , 0.012 kg of Co ₃ O ₄ and 0.43 kg of glucose (C ₆ H ₁₂ O ₆ ), firstly mix WO _2.9 , Co ₃ O ₄ and absolute ethanol by ball milling, the mass ratio of balls to powder is 10:1, the volume ratio of absolute ethanol to material is 1:1, the speed of the ball mill is 100r/min, and the ball milling time is 60 hours. Glucose powder was added to the mixed oxide powder, and anhydrous ethanol having an equal volume ratio to the glucose powder was added for secondary ball milling. The ball milling speed was 70r/min, and the ball milling time was 15h. Place the above powder in a vacuum furnace for reaction with a vacuum degree of 10 Pa. First, heat it to 160°C and keep it for 30 minutes, then raise the temperature to 400°C and keep it for 3 hours, and finally raise the temperature to 950°C and keep it for 3 hours to prepare a nanocomposite with WC distributed on the W matrix. Powder, wherein the mass ratio of WC is 10%. The morphology of the raw material powders mixed by ball milling in this example is shown in Figure 1, the morphology of the raw material powders after ball milling and mixed with glucose coating is shown in Figure 2, and the composition analysis results of the prepared composite powders are shown in Table 1.

Example 2

Weigh 1 kg of WO ₃ , 0.05 kg of Co ₃ O ₄ and 0.45 kg of glucose (C ₆ H ₁₂ O ₆ ), firstly mix and ball mill WO ₃ , Co ₃ O ₄ and absolute ethanol, and the mass ratio of milling balls to powder is 5:1, the volume ratio of absolute ethanol to material is 1:1, the ball mill speed is 300r/min, and the ball milling time is 70 hours. Glucose powder was added to the mixed oxide powder, and anhydrous ethanol with an equal volume ratio to the glucose powder was added to carry out secondary ball milling. The ball milling speed was 80r/min, and the ball milling time was 10h. Put the above powder in a vacuum furnace for reaction with a vacuum degree of 0.1 Pa. First, heat it to 180°C and keep it for 15 minutes, then raise the temperature to 500°C and keep it for 2 hours, and finally raise the temperature to 1100°C and keep it for 2 hours to prepare WC nano Composite powder, wherein the mass ratio of WC is 15%. The morphology and particle size distribution of the tungsten-based composite powder prepared in this example are shown in Figure 3, and the composition analysis results of the prepared composite powder are shown in Table 1.

Example 3

Weigh 1 kg of WO _2.9 , 0.1 kg of Co ₃ O ₄ and 0.5 kg of glucose (C ₆ H ₁₂ O ₆ ), first mix and ball mill WO _2.9 , Co ₃ O ₄ powder and absolute ethanol, the mass of the ball and the powder The ratio is 3:1, the volume ratio of absolute ethanol to material is 1:1, the speed of the ball mill is 500r/min, and the ball milling time is 80 hours. Glucose powder was added to the mixed oxide powder, and anhydrous ethanol having an equal volume ratio to the glucose powder was added for secondary ball milling. The ball milling speed was 50 r/min, and the ball milling time was 20 h. Put the above powder in a vacuum furnace for reaction with a vacuum degree of 0.02 Pa. First, heat it to 150°C and keep it for 60 minutes, then raise the temperature to 350°C and keep it for 4 hours, and finally raise the temperature to 850°C and keep it for 5 hours. Composite powder, wherein the mass ratio of WC is 20%. The phase detection results of the tungsten-based composite powder prepared in this example are shown in FIG. 4 , and the component analysis results of the tungsten-based composite powder prepared in this example are shown in Table 1.

The compositional analysis results of the nano-tungsten-based composite powders prepared in different examples in table 1

Claims (3)

1. An industrialized preparation method of nanometer W/WC composite powder, characterized in that, comprising the following steps: (1) Using tungsten oxide, cobalt oxide and glucose as raw materials, the mass ratio of cobalt oxide: tungsten oxide: glucose is 1: (10-85): (4.5-43) for batching, first oxidize tungsten The material and cobalt oxide are subjected to high-energy ball milling, the mass ratio of balls to powder is 3:1-10:1, absolute ethanol is used as the grinding medium, the volume ratio of grinding medium to material is 1:1, and the speed of the ball mill is 100-500r/ min, ball milling time is 60~80h; (2) Add glucose powder to the mixed powder obtained in step (1), and add dehydrated alcohol in an equal volume ratio to glucose to carry out secondary ball milling, the ball milling speed is 50-80r/min, and the ball milling time is 10-20h; (3) Put the powder obtained in step (2) in a vacuum furnace for reaction, the vacuum degree in the furnace is less than 10Pa, first heat to 150-180°C and keep it for 15-60min, then raise the temperature to 350-500°C and keep it for 2-4h, Finally, the temperature was raised to 850-1100°C for 2-5 hours. 2. According to the industrial preparation method of a kind of nano W/WC composite powder according to claim 1, it is characterized in that the mole number of carbon in glucose is greater than the mole number of oxygen in tungsten oxide and cobalt oxide. 3. The industrial preparation method of a nano W/WC composite powder according to claim 1, characterized in that a small amount of cobalt exists in the composite powder in the form of W-Co-C ternary phase.