CN103526060A - Rapid preparation method of copper-tungsten alloy - Google Patents

Abstract

The invention relates to a rapid preparation method of a copper-tungsten alloy, and belongs to the fields of a powder metallurgy technology, a metallurgical new technology and a microwave sintering technology. The method comprises the following steps: carrying out ball milling mixing of metallic tungsten powder and copper powder according to a proportion ratio of 95-70wt%:5-30wt%, carrying out briquet pressing to prepare a tungsten skeleton briquet, filling into a mullite crucible, distributing the copper powder surrounding the tungsten skeleton briquet, putting the crucible under conditions comprising a microwave frequency of 2400-2500MHz, a power of 3-5KW and a degree of vacuum of below 0.1KPa, sintering for 1-3h by heating to 1100-1300DEG C at a heating speed of 15-20DEG C/min, and naturally cooling to obtain the copper-tungsten alloy. The copper-tungsten alloy prepared through the method has a uniform structure and a compact structure, and has a relative density reaching 98.7%.

Description

A kind of rapid preparation method of copper-tungsten alloy

technical field

The invention relates to the fields of powder metallurgy technology, new metallurgical technology and microwave sintering technology, in particular to a rapid preparation method of copper-tungsten alloy.

Background technique

Copper-tungsten alloy not only has the high melting point, high density, electric corrosion resistance, welding resistance and high high temperature strength of W, but also has the high electrical and thermal conductivity, plasticity and processability of Cu. Because Cu can absorb a large amount of arc energy when it evaporates at high temperature in the arc, reduce the arc temperature, improve the use conditions and reduce the electric corrosion, it is widely used as the electrical contact material of high-voltage electrical appliances, and also used as the electrode of electric processing, High-temperature molds and other occasions that require electrical and thermal conductivity and high-temperature use. At present, the infiltration method and the activated liquid phase sintering method are generally used to prepare W-Cu materials. However, due to the immiscibility of W and Cu, the structure of traditional infiltrated W-Cu materials is segregated, coarse and low in relative density. In addition, activated liquid phase sintering will introduce heterogeneous impurities and affect the performance of the material. Microwave sintering technology is a method that uses the special wave band of microwave to couple with the material to generate heat, and heat the material as a whole to the sintering temperature to achieve densification. Compared with conventional sintering technology, it has low sintering temperature, short sintering time, and high energy utilization rate And the advantages of high heating efficiency, and the manufactured workpiece has high density, hardness and toughness, and has excellent comprehensive performance.

The application number is 2009103041144 "A method for preparing W-CU alloy by microwave infiltration sintering", which is to mix copper powder and tungsten powder by ball milling to form a W skeleton, electrolytic copper powder to make an infiltration Cu compact, and auxiliary heating The material SiC sheets are placed together in an alumina fiber insulation sheath, and then sintered under microwave conditions and a mixed protective gas atmosphere. The above-mentioned invention uses microwave-assisted heating of SiC sheets and conditions of atmosphere protection to realize the sintering preparation of alloys. Compared with traditional preparation methods, microwaves can quickly heat SiC sheets and transfer heat to alloy compacts, which is an excellent heat transfer method. In the indirect heat conduction method, the heating rate and energy conversion efficiency are lower than direct microwave heating.

Contents of the invention

In order to overcome the deficiencies in the prior art, the present invention proposes a rapid preparation method of copper-tungsten alloy, which utilizes microwaves to directly heat metal copper powder until melting, and realizes rapid sintering of metal compacts under vacuum conditions, which is different from traditional heating Compared with other methods, this method generates heat by coupling the special waveband of microwaves with the basic fine structure of the material, heating the material as a whole to the melting temperature, and has the advantages of fast heating speed and high energy conversion rate.

The invention combines microwave smelting metal powder, microwave sintering technology, powder metallurgy technology and infiltration sintering method to prepare copper-tungsten alloy, which is a method for rapidly preparing copper-tungsten alloy. The specific steps include the following:

(1) The metal tungsten powder and copper powder are ball milled and mixed according to the mass percentage of 95-70wt%: 5-30% respectively;

(2) Press the tungsten powder and copper powder mixed by ball milling in step (1) into a block to make a tungsten skeleton block;

(3) Put the tungsten skeleton block into the mullite crucible, and cover the tungsten skeleton block with copper powder with a thickness of 2-5mm, and then place it in a microwave frequency of 2400-2500MHz, power 3-5KW, vacuum degree Under the condition of less than 0.1KPa, keep the heating rate of 15-20°C/min, raise the temperature to 1100-1300°C for sintering for 1-3 hours, and cool naturally to obtain copper-tungsten alloy.

The particle size of the metal tungsten powder and the copper powder are both less than 200 mesh, and the purity is both greater than 99.8wt%.

During the ball milling and mixing, ball milling is carried out for 10 to 40 minutes under the conditions of a ball-to-material ratio of 1 to 50:1 and a rotational speed of 100 to 300 r/min.

The pressure when pressing the compact is controlled at 25-45 MPa, and the pressure is controlled according to the content of copper powder in the compact. When the content of mixed copper powder is low, the pressing pressure is high, otherwise it is small.

The beneficial effects of the present invention are:

(1) It mainly reflects rapid preparation, because it adopts microwave sintering, which can directly melt metal copper powder, and has the characteristics of fast heating speed and high thermal efficiency. By adjusting the microwave power, metal copper powder can be melted in 40~50 minutes;

(2) The mullite crucible used is a wave-transparent ceramic, which can achieve the purpose of direct heating of metal copper powder by microwaves, instead of heating microwave-absorbing materials such as silicon carbide sheets and then indirect heating through heat transfer;

(3) The infiltrated copper used in the present invention is metallic copper powder, rather than metallic copper ingots. Copper powder is used not only as a wave-absorbing carrier, but also as an infiltrated substance, which can also prevent the oxidation of the alloy surface during the sintering process of the alloy. In addition to preparing copper-tungsten alloys, this method can also be applied in other copper infiltration processes;

(4) The present invention is sintered under vacuum conditions, without atmosphere protection, with simple process flow and excellent alloy properties.

Description of drawings

Fig. 1 is the process flow diagram of the rapid preparation method of copper-tungsten alloy of the present invention;

Fig. 2 is the copper-tungsten alloy microstructural figure of infiltration sintering after adding 8% copper powder of the present invention;

Fig. 3 is a microstructure diagram of copper-tungsten alloy infiltrated and sintered after adding 20% copper powder in the present invention.

Detailed ways

The present invention will be further described below in combination with the accompanying drawings and specific embodiments.

Embodiment 1: The rapid preparation method of the copper-tungsten alloy of this embodiment is:

(1) The metal tungsten powder and copper powder are ball milled and mixed according to the mass percentage of 92wt%: 8wt%, and the ball milled

According to the ball-to-material ratio of 50:1 and the speed of 100r/min, ball milling is carried out for 40 minutes; the particle size of metal tungsten powder and copper powder is 10-20μm, and the purity is greater than 99.8wt%.

(2) Press the tungsten powder and copper powder mixed by ball milling in step (1) into a compact, and the pressure is controlled at 30MPa to make a cylindrical tungsten skeleton compact;

(3) Put the tungsten skeleton block into the mullite crucible, and cover the tungsten skeleton block with copper powder with a thickness of 3mm, and then place it under the conditions of microwave frequency 2400MHz, power 5KW, and vacuum degree 0.08KPa. Maintain a heating rate of 20°C/min, raise the temperature to 1200°C and sinter for 1.2 hours, and then cool naturally to obtain a copper-tungsten alloy. After analyzing the sample, the copper-tungsten alloy has a Brinell hardness of 229 and a relative density of 95.4%. The microstructure is shown in Figure 2.

Embodiment 2: The rapid preparation method of the copper-tungsten alloy of this embodiment is:

(2) The metal tungsten powder and copper powder are ball milled and mixed according to the mass percentage of 80wt%: 20%, and the ball milled

According to the ball-to-material ratio of 30:1 and the speed of 200r/min, ball milling was carried out for 20 minutes; the particle size of metal tungsten powder and copper powder were both less than 200 mesh, and the purity was greater than 99.8wt%.

(2) Press the tungsten powder and copper powder mixed by ball milling in step (1) into a compact, and the pressure is controlled at 45MPa to make a tungsten skeleton compact;

(3) Put the tungsten skeleton block into the mullite crucible, and cover the tungsten skeleton block with copper powder with a thickness of 2mm, and then place it under the conditions of microwave frequency 2500MHz, power 3KW, and vacuum degree less than 0.1KPa , maintain a heating rate of 15°C/min, raise the temperature to 1300°C and sinter for 1 hour, and then naturally cool to obtain a copper-tungsten alloy. The sample is analyzed, and the copper-tungsten alloy has a Brinell of 221 and a relative density of 98.7%. The microstructure is shown in Figure 3.

Embodiment 3: The rapid preparation method of the copper-tungsten alloy of this embodiment is:

(1) The metal tungsten powder and copper powder are ball milled and mixed according to the mass percentage of 95wt%: 5%.

According to the ball-to-material ratio of 1:1 and the speed of 300r/min, ball milling was carried out for 10 minutes; the particle size of metal tungsten powder and copper powder were both less than 200 mesh, and the purity was greater than 99.8wt%.

(2) Press the tungsten powder and copper powder mixed by ball milling in step (1) into a compact, and the pressure is controlled at 25MPa to make a tungsten skeleton compact;

(3) Put the tungsten skeleton block into the mullite crucible, and cover the tungsten skeleton block with copper powder with a thickness of 5mm, and then place it under the conditions of microwave frequency 2450MHz, power 3.5KW, and vacuum degree less than 0.1KPa , maintain a heating rate of 18°C/min, raise the temperature to 1100°C for sintering for 3 hours, and cool naturally to obtain a copper-tungsten alloy.

Embodiment 4: The rapid preparation method of the copper-tungsten alloy of this embodiment is:

(1) The metal tungsten powder and copper powder are ball milled and mixed according to the mass percentage of 70wt%: 30%.

The material is ball milled for 30 minutes under the conditions of a ball-to-material ratio of 20:1 and a rotational speed of 200r/min; the particle size of metal tungsten powder and copper powder are both less than 200 mesh, and the purity is greater than 99.8wt%.

(2) Press the tungsten powder and copper powder mixed by ball milling in step (1) into a compact, and the pressure is controlled at 25MPa to make a tungsten skeleton compact;

(3) Put the tungsten skeleton block into the mullite crucible, and cover the tungsten skeleton block with copper powder with a thickness of 2.5mm, and then place it in a microwave oven with a microwave frequency of 2500MHz, a power of 3.8KW, and a vacuum degree of less than 0.1KPa. Under the conditions, keep the heating rate of 17°C/min, raise the temperature to 1250°C for sintering for 3 hours, and cool naturally to obtain copper-tungsten alloy.

The specific embodiments of the present invention have been described in detail above in conjunction with the accompanying drawings, but the present invention is not limited to the above embodiments. Variations.

Claims (4)

1. a fast preparation method for copper-tungsten, is characterized in that concrete steps comprise:

(1) metal tungsten powder and copper powder are carried out to ball mill mixing according to mass percent 95～70wt%:5～30% respectively;

(2) tungsten powder and the copper powder that ball milling in step (1) are mixed carry out briquet compacting, make W skeleton briquet;

(3) pack W skeleton briquet into mullite crucible, and be covered with at W skeleton briquet the copper powder that thickness is 2～5mm around, then being placed in microwave frequency is that 2400～2500MHz, power 3～5KW, vacuum tightness are less than under the condition of 0.1KPa, keep the rate of heating of 15～20 ℃/min that temperature is risen to 1100～1300 ℃ of sintering 1～3 hour, naturally cooling obtains copper-tungsten.

2. the fast preparation method of copper-tungsten according to claim 1, is characterized in that: the granularity of described metal tungsten powder and copper powder is all less than 200 orders, and purity is all greater than 99.8wt%.

3. the fast preparation method of copper-tungsten according to claim 1, is characterized in that: during described ball mill mixing, according to ratio of grinding media to material, be ball milling 10～40min under 1～50:1, the rotating speed condition that is 100～300r/min.

4. the fast preparation method of copper-tungsten according to claim 1, is characterized in that: pressure-controlling during described compacting briquet is at 25～45MPa.

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