阅读说明：本技术 一种电子束熔渗生产铜钨触头的方法 (Method for producing copper-tungsten contact by electron beam infiltration ) 是由 康迪 周宁 周兴 邵红颜 刘萍 王小军 于 2020-03-26 设计创作，主要内容包括：本发明提供了一种电子束熔渗生产铜钨触头的方法,包括以下步骤：S1：将钨粉、铜粉分别置于混料机中混料；S2：将混料后的钨粉压制成圆形钨坯,将混料后的铜粉平均分为两份,分别压制成圆形铜坯；S3：将圆形钨坯、圆形铜坯置于真空烧结炉中真空烧结；S4：将烧结钨坯放入石墨坩埚中,圆形铜坯放置在烧结钨坯上,置于电子束真空烧结设备中真空熔渗,将熔渗后坯料取出翻面后再次放入石墨坩埚中,取另一个圆形铜坯置于熔渗钨坯上,再次真空熔渗,冷却得到铜钨触头材料。总之,本发明具有工艺完善、制备效率高、材料性能优等优点。(The invention provides a method for producing a copper-tungsten contact by electron beam infiltration, which comprises the following steps: s1: placing tungsten powder and copper powder in a mixer respectively for mixing; s2: pressing the mixed tungsten powder into a circular tungsten blank, averagely dividing the mixed copper powder into two parts, and respectively pressing into circular copper blanks; s3: placing the round tungsten blank and the round copper blank in a vacuum sintering furnace for vacuum sintering; s4: and putting the sintered tungsten blank into a graphite crucible, putting the circular copper blank on the sintered tungsten blank, putting the sintered tungsten blank into electron beam vacuum sintering equipment for vacuum infiltration, taking the infiltrated blank out, turning over the blank, putting the blank into the graphite crucible again, taking the other circular copper blank, putting the other circular copper blank on the infiltrated tungsten blank, performing vacuum infiltration again, and cooling to obtain the copper-tungsten contact material. In a word, the invention has the advantages of perfect process, high preparation efficiency, excellent material performance and the like.)

1. The method for producing the copper-tungsten contact by electron beam infiltration is characterized by mainly comprising the following steps of:

s1: premixing raw materials

Placing 2-10 mu m tungsten powder into a mixer, adding an adhesive accounting for 1-5% of the mass of the tungsten powder into the tungsten powder, and mixing for 8-16 h;

selecting copper powder with the mass of 4-7 mu m equal to that of tungsten powder, placing the copper powder in a mixer, adding zinc powder with the mass of 0.5-3% of the copper powder and a lubricant with the mass of 0.1-1% of the copper powder into the copper powder, and mixing for 10-15 h;

s2: blank forming

Pressing the mixed tungsten powder into a circular tungsten blank by using a 200t hydraulic press;

averagely dividing the mixed copper powder into two parts, and respectively pressing by using a 200t hydraulic press to obtain two round copper blanks;

s3: blank pre-firing

Placing the round tungsten blank in a vacuum sintering furnace, carrying out heat treatment for 1-2h at the temperature of 700-800 ℃ in a nitrogen atmosphere, and then pumping the vacuum degree in the vacuum sintering furnace to 3.0 +/-0.5 × 10^-2Pa, raising the temperature in the vacuum sintering furnace to 1400-1600 ℃, keeping the temperature constant, sintering for 3-5h, and cooling to obtain a sintered tungsten blank;

s4: electron beam infiltration

Placing the sintered tungsten blank into a graphite crucible, placing a round copper blank on the sintered tungsten blank, placing the graphite crucible into electron beam vacuum sintering equipment, and pumping the vacuum degree in the electron beam vacuum sintering equipment to 4.5 +/-0.1 × 10^-2Pa, setting the cladding voltage of the electron beam to be 60 +/-5 kV, setting the current to be 40 +/-10 mA, setting the scanning speed to be 300-108W/cm, and setting the energy of the electron beam to be 106-108W/cm²Then, beginning infiltration, wherein the infiltration time is 1 plus or minus 0.2h, and cooling to obtain an infiltration blank;

and taking out the infiltration blank, turning over the infiltration blank, putting the infiltration blank into the graphite crucible again, taking another round copper blank, putting the graphite crucible on an infiltration tungsten blank, putting the graphite crucible into electron beam vacuum sintering equipment, carrying out infiltration for 1 +/-0.2 h according to the infiltration parameters, and cooling to obtain the copper-tungsten contact material.

2. The method for producing copper-tungsten contact according to claim 1, wherein the purity of the selected tungsten powder is 99.9% and the purity of the selected copper powder is 99.99%.

3. The method for producing the copper-tungsten contact through electron beam infiltration according to claim 1, wherein the adhesive is obtained by mixing silicon carbide pellets, stearic acid and deionized water in a mass ratio of 3:1:10, and the lubricant is obtained by polymerizing zinc stearate, monoglyceride and EBS lubricant in a mass ratio of 1:1: 5.

4. The method for producing the copper-tungsten contact through electron beam infiltration according to claim 1, wherein the lubricant is obtained by polymerizing zinc stearate, monoglyceride and EBS lubricant in a mass ratio of 1:1: 5.

5. The method for producing the copper-tungsten contact through electron beam infiltration according to claim 1, wherein in S2, the specific process of press forming the round tungsten blank is as follows: preheating the mixed tungsten powder at the temperature of 500 ℃ for 10-20min at 300 ℃, placing the tungsten powder in a circular die, pressing and molding the tungsten powder by using a 200t hydraulic press, and repeatedly pressing the tungsten powder by using a 300t hydraulic press after the blank is cooled to obtain the tungsten powder with the density of 20.00 +/-0.75 g/cm³The circular tungsten blank of (1);

the specific process for press forming the two round copper blanks comprises the following steps: evenly dividing the mixed copper powder into two parts, preheating at 200-300 ℃, then respectively placing the two parts into a circular die with the same diameter as the circular die for the tungsten powder, pressing and forming the two parts by using a 200t hydraulic press, and repeatedly pressing the blank by using 300t hydraulic pressure after the blank is cooled to obtain two blocks with the density of 7.00 +/-0.25 g/cm³The round copper billet of (1).

6. The method for producing copper-tungsten contact according to claim 1, wherein in S4, graphite paper is laid in the graphite crucible before the sintered tungsten blank is placed in the graphite crucible, and the graphite paper is replaced before the sintered tungsten blank is placed in the graphite crucible again after the sintered tungsten blank is taken out and turned over.

7. The method of claim 1, wherein in step S4, the electron beam spot scanned on the circular copper blank is in the shape of a circular wave, the diameter of the circular wave is equal to the radius of the circular copper blank, the scanning track of the electron beam spot is a circle with the center of the circular copper blank as the scanning origin and the radius of 1/2 of the circular copper blank as the scanning radius.

Technical Field

The invention belongs to the technical field of electric contact manufacturing, and particularly relates to a method for producing a copper-tungsten contact by electron beam infiltration.

Background

The tungsten-copper contact is a composite material refined by the processes of static pressure forming, high-temperature sintering and copper infiltration by utilizing the excellent metal characteristics of high-purity tungsten powder and the advantages of plasticity, high conductivity and the like of high-purity red copper powder. The tungsten copper contact has the characteristics of excellent arc burning resistance and fusion welding resistance, good arc breaking performance, good electric and heat conduction, small thermal expansion, no softening at high temperature, high strength, high density, high hardness and the like. Has good electric and thermal conductivity, good high-temperature strength and certain plasticity. At temperatures above 3000 ℃, copper in the alloy is liquefied and evaporated, absorbs a large amount of heat, and lowers the surface temperature of the material, so that the material is also called a metal sweat material. Tungsten-copper contacts are widely used as contacts and protection rings of high-voltage and super-hydraulic switches and circuit breakers, and are used for electric heating upsetting anvil block materials, automatic submerged arc welding conductive tips, plasma cutting machine nozzles, electric welding machines, welding heads of butt welding machines, roll welding wheels, gas sealing rivet electrodes and spark electrodes, spot welding, butt welding materials and the like.

The traditional production process uses a vacuum furnace or an atmosphere protection furnace for sintering and copper infiltration, a heating body generates heat and then heats a workpiece in a heat conduction and convection mode, the whole hearth is heated, and the energy consumption is high. The whole sintering process comprises three links of heating up, high-temperature sintering and cooling down, the duration is more than 30 hours, the efficiency is low, and the method is only suitable for batch production.

The invention designs a copper-tungsten contact production method which aims at solving the problem of production efficiency of small-batch and multi-specification test materials and reducing production energy consumption.

Disclosure of Invention

Aiming at the problems, the invention provides a method for producing a copper-tungsten contact by electron beam infiltration.

The technical scheme of the invention is as follows: a method for producing a copper-tungsten contact by electron beam infiltration mainly comprises the following steps:

s1: premixing raw materials

Placing 2-10 mu m tungsten powder into a mixer, adding an adhesive accounting for 1-5% of the mass of the tungsten powder into the tungsten powder, and mixing for 8-16 h;

selecting copper powder with the mass of 4-7 mu m equal to that of tungsten powder, placing the copper powder in a mixer, adding zinc powder with the mass of 0.5-3% of the copper powder and a lubricant with the mass of 0.1-1% of the copper powder into the copper powder, and mixing for 10-15 h;

s2: blank forming

Pressing the mixed tungsten powder into a circular tungsten blank by using a 200t hydraulic press;

averagely dividing the mixed copper powder into two parts, and respectively pressing by using a 200t hydraulic press to obtain two round copper blanks;

s3: blank pre-firing

Placing the round tungsten blank in a vacuum sintering furnace, carrying out heat treatment for 1-2h at the temperature of 700-800 ℃ in a nitrogen atmosphere, and then pumping the vacuum degree in the vacuum sintering furnace to 3.0 +/-0.5 × 10^-2Pa, raising the temperature in the vacuum sintering furnace to 1400-1600 ℃, keeping the temperature constant, sintering for 3-5h, and cooling to obtain a sintered tungsten blank;

s4: electron beam infiltration

Placing the sintered tungsten blank into a graphite crucible, placing a round copper blank on the sintered tungsten blank, placing the graphite crucible into electron beam vacuum sintering equipment, and pumping the vacuum degree in the electron beam vacuum sintering equipment to 4.5 +/-0.1 × 10^-2Pa, setting the cladding voltage of the electron beam to be 60 +/-5 kV, setting the current to be 40 +/-10 mA, setting the scanning speed to be 300-108W/cm, and setting the energy of the electron beam to be 106-108W/cm²Then, beginning infiltration, wherein the infiltration time is 1 plus or minus 0.2h, and cooling to obtain an infiltration blank;

and taking out the infiltration blank, turning over the infiltration blank, putting the infiltration blank into the graphite crucible again, taking another round copper blank, putting the graphite crucible on an infiltration tungsten blank, putting the graphite crucible into electron beam vacuum sintering equipment, carrying out infiltration for 1 +/-0.2 h according to the infiltration parameters, and cooling to obtain the copper-tungsten contact material.

Preferably, the purity of the selected tungsten powder is 99.9%, the purity of the copper powder is 99.99%, and the influence of impurities on the performance of the copper-tungsten contact is avoided in terms of the purity of the raw materials.

Preferably, the adhesive is obtained by mixing silicon carbide pellets, stearic acid and deionized water in a mass ratio of 3:1:10, the adhesive is good in volatility, less in residues and free of influence on the strength of the copper-tungsten contact, and the lubricant is polymerized by zinc stearate, monoglyceride and EBS lubricant in a mass ratio of 1:1:5, so that the friction force among copper powder is reduced, and the density of a pressed blank is increased.

Further, in S2, the specific process of press forming the circular tungsten blank is as follows: preheating the mixed tungsten powder at the temperature of 300 ℃ and 500 ℃ for 10-20min, then placing the tungsten powder into a circular die, pressing and molding the tungsten powder by using a 200t hydraulic press, cooling the blank, and then repeatedly pressing the blank by using a 300t hydraulic press to obtain a circular tungsten blank with the density of 20.00 +/-0.75 g/cm3, preheating to increase the activity of the surface of the tungsten powder, and repeatedly pressing to ensure the density of the pressed tungsten blank;

the specific process for press forming the two round copper blanks comprises the following steps: the mixed copper powder is averagely divided into two parts, the two parts are preheated at the temperature of 200-300 ℃, then are respectively placed in a circular die with the same diameter as the tungsten powder circular die, a 200t hydraulic press is used for pressing and forming, after the blank is cooled, the blank is pressed repeatedly by the hydraulic pressure of 300t, two circular copper blanks with the density of 7.00 +/-0.25 g/cm3 are obtained, the surface activity of the copper powder is increased by preheating, and the density of the pressed copper blanks is ensured by repeated pressing.

Further, 99.9% of nitrogen is continuously introduced into the vacuum sintering furnace in the S3 for protection in the whole blank pre-sintering process, the introduced nitrogen flow is 0.3-0.5m3/h, the nitrogen can play a role in protection in the sintering process, and the circulated nitrogen can carry away impurity metal vapor released by the blank in the sintering process, so that the phenomenon that the oxide layer is formed on the surface of the blank to influence the performance of the copper-tungsten contact material is avoided.

Preferably, in S4, before the sintered tungsten blank is placed in the graphite crucible, graphite paper is laid in the graphite crucible, after the infiltrated blank is taken out and turned over, the graphite paper is replaced before the sintered tungsten blank is placed in the graphite crucible again, the graphite paper separates the blank from the inner wall of the graphite crucible, the blank is placed to be bonded with the inner wall of the graphite crucible in the sintering process, and the damage of electron beam infiltration to the graphite crucible is reduced.

Further, in S4, the shape of the electron beam spot scanned on the circular copper blank by the electron beam is a circular wave, the diameter of the circular wave is equal to the radius of the circular copper blank, the scanning track of the electron beam spot is a circle with the center of the circular copper blank as the scanning origin and the radius of the 1/2 circular copper blank as the scanning radius, the scanning track is a closed-loop circle, the surface of the copper blank is completely scanned and infiltrated, and uneven dispersion of the copper-tungsten contact material caused by repeated scanning and infiltration is avoided.

The invention has the beneficial effects that: the invention provides a method for producing copper-tungsten contacts by electron beam infiltration, which is suitable for single-piece or small-batch sample production in the product development process, wherein copper powder and tungsten powder are pressed into a round blank, the copper blank is placed above a tungsten blank and placed in a graphite crucible, electron current emitted by a cathode filament is accelerated by using accelerating voltage, the surface of the copper blank is bombarded by high-speed electron current, kinetic energy is converted into heat energy, and thus the copper blank is infiltrated into the tungsten blank. In a word, the invention has the advantages of perfect process, high preparation efficiency, excellent material performance and the like.

Drawings

FIG. 1 is a graph of EPMA detection profiles prior to infiltration;

FIG. 2 shows the EPMA detection profile after infiltration.

Detailed Description

For the understanding of the technical solutions of the present invention, the following description is further illustrated with reference to fig. 1-2 and specific examples, which are not intended to limit the scope of the present invention.