CN101624662B - A method for preparing W-Cu alloy by microwave infiltration - Google Patents

Abstract

The invention relates to a method for preparing W-Cu alloy in a microwave infiltration way, which comprises the following steps: 1. dispensing W powder and reduced Cu powder according to the weight percentage of W-3Cu, then ball-milling and mixing; 2. fetching the mixed powder and electrolytic copper powder according to design components, and respectively pressing the mixed powder under the pressure of 150-510MPa to form a cylindrical W framework and an infiltrated Cu pressed billet; 3. putting the pressed cylindrical W framework, the infiltrated Cu pressed billet and SiC slices into an alumina fiber heat-preserving sheath and then putting the sheath into an oven chamber of a microwave high-temperature oven, and vacuumizing the oven chamber to the vacuum degree within 100Pa by a vacuum pump; 4. injecting mixed protection gases of N2 and H2 into the oven chamber of the microwave oven, regulating the output power of the microwave high-temperature oven, heating to about 1350 DEG C at a temperature-rise speed of about 30 DEG C/min, preserving the heat, powering the microwave oven off and cooling to obtain the ideal alloy. The invention has simple process, convenient operation, short sintering period, low energy consumption and excellent performance of the obtained W-Cu alloy and can substitute for the prior process for preparing the W-Cu alloy in an infiltration way.

Description

A method for preparing W-Cu alloy by microwave infiltration

technical field

The invention discloses a method for preparing W-Cu alloy. In particular, it refers to a method for preparing W-Cu alloy by microwave infiltration.

Background technique:

W-Cu alloy is a pseudo-alloy material composed of tungsten with high melting point, high hardness, low expansion coefficient and copper with high plasticity, high electrical conductivity and thermal conductivity. It has good arc erosion resistance, welding resistance, It has the advantages of high temperature resistance, oxidation resistance, and high strength; it is currently widely used in industrial production such as electrical contact materials, electronic packaging materials, resistance welding, EDM materials, plasma spraying electrode materials, and military materials.

The infiltration method is a common method for preparing W-Cu alloys in industrial production. The traditional process usually takes measures such as slow heating rate (about 5-10°C/min) and intermediate temperature insulation in the resistance furnace to avoid temperature gradients. Too large will cause defects such as alloy deformation and bubbling, and the obtained material has high relative density and good overall performance, but the only disadvantage is that the production process cycle is long and complicated, and the production cost is high.

Contents of the invention

The purpose of the present invention is to overcome the deficiencies of the prior art and provide a method for preparing W-Cu alloy by microwave infiltration with simple process, convenient operation, short sintering cycle, low energy consumption and excellent performance of the W-Cu alloy. .

A kind of microwave infiltration method of the present invention prepares W-Cu alloy, comprises following process step:

The first step: W powder with a purity greater than 99.9% and an average particle size of 2 to 4 microns, and reduced Cu powder with a purity greater than 99.7% and an average particle size of 20 to 50 microns are mixed according to the mass percentage of W-3Cu, and ball milled for 5 to 7 hours ;

Step 2: Add 0.5-1.5% stearic acid as a forming agent to the mixed and dried powder to improve its compressibility. According to the design composition, take the mixed powder and the electrolytic powder with a purity of >99.7% and a particle size of 60-90 microns. The copper powder is pressed under the pressure of 150~510MPa to respectively press the cylindrical W skeleton and the infiltrated Cu compact;

The third step: put the pressed cylindrical W skeleton, infiltrated Cu compact and auxiliary heating material SiC sheet into the alumina fiber insulation sheath, then put it into the microwave high-temperature furnace cavity, and use a vacuum pump to pump the furnace cavity To within 100Pa of vacuum;

Step 4: Inject N ₂ and H ₂ mixed protective gas into the cavity of the microwave oven, adjust the output power of the microwave high-temperature furnace, heat to 1300-1400°C at a heating rate of 25-35°C/min, and keep warm for 15-25 minutes. Turn off the microwave oven and obtain the desired alloy after cooling.

In the present invention, the planetary ball mill is used for the ball milling, the ball milling medium is absolute ethanol, the rotating speed is 100-200 rpm, and the ball-to-material ratio is 2:1.

In the present invention, the added amount of the auxiliary heating material SiC sheet is 100-140 g.

In the present invention, the gas volume ratio of N ₂ and H ₂ in the mixed protective gas of N ₂ and H ₂ is: N ₂ : _{H 2} =(85-95):(5-15).

In the present invention, the infiltrated Cu compact is placed above the cylindrical W skeleton and placed in an alumina fiber insulation sheath as a whole.

In the present invention, Cu powder in the W-3Cu mixed powder is an inducer.

Due to the adoption of the above process, the present invention utilizes microwaves to use electromagnetic energy as power, microwaves as energy carriers, internal heat generation, volume heating and other characteristics, so that the sintering process has the characteristics of fast heating speed, short sintering time, and high energy utilization rate. Studies have proved that microwave sintering can make sintered products fine grain, uniform structure and improved performance; and the production cycle is short and energy saving; because microwave sintering is volume heating, it overcomes the traditional sintering process of slow heating up and intermediate temperature insulation in resistance furnaces, so as to Avoid defects such as alloy deformation and bubbling caused by excessive temperature gradients; at the same time, adding an appropriate amount of SiC as an auxiliary heating material during microwave sintering can not only promote rapid temperature rise of the sample, but also make the temperature of the sample more uniform. Compared with prior art, the present invention has following advantage:

1. The process of the present invention is simple, the energy consumption is small, and the cost is low. The alloy prepared by microwave infiltration method only needs about 1 hour to complete the whole sintering process, and it can be taken out after 1.5 hours of furnace cooling.

2. The present invention uses a faster heating rate (30°C/min) for heating in a microwave high-temperature furnace, and the sintered W-Cu alloy sample has a more uniform structure. At the same time, microwave sintering has basic characteristics such as volume heating and non-thermal effects. Therefore, Compared with the alloy sintered in a resistance furnace by the conventional infiltration method, the W-Cu alloy prepared by the invention has finer crystal grains, more uniform microstructure and improved properties.

In summary, the present invention has simple process, convenient operation, short sintering period, low energy consumption, and excellent performance of the prepared W-Cu alloy, which can replace the existing infiltration process for preparing W-Cu alloy.

Detailed ways:

Example 1:

The first step: mix W powder with a purity greater than 99.9% and an average particle size of 2 to 4 microns, and reduced Cu powder with a purity greater than 99.7% and an average particle size of 20 to 50 microns according to the mass percentage of W-3Cu, and use a planetary ball mill to The powder was mixed in the water-ethanol medium for 7 hours, the rotation speed was 200 rpm, and the ball-to-material ratio was 2:1.

The second step: adding 1.5% stearic acid as a forming agent to the mixed and dried powder to improve its compressibility. Weigh 10.2g of mixed powder and 1.80g of electrolytic copper powder with a purity of >99.7% and a particle size of 60-90 microns according to the W-18Cu composition, and press a cylindrical W skeleton with a diameter of φ18mm and an infiltrated Cu compact under a pressure of 510MPa.

Step 3: Place the pressed cylindrical W skeleton, infiltrated Cu compact and 140g of auxiliary heating material SiC sheet in the alumina fiber insulation sheath, place the infiltrated Cu compact on the top of the cylindrical W skeleton, and then place into the cavity of a microwave high-temperature furnace, and use a vacuum pump to pump the cavity to a vacuum of less than 100Pa;

Step 4: Introduce N ₂ and H ₂ mixed protective gas with N ₂ and H ₂ gas volume ratio: N ₂ : _{H 2} =85:15 into the cavity of the microwave oven, and adjust the output power of the microwave high-temperature furnace to 35°C /min heating rate to 1400°C, keep warm for 25 minutes, turn off the microwave oven, and obtain the ideal alloy after cooling.

The performance parameters of the alloy obtained after cooling are: the relative density reaches 97.7%, the electrical conductivity is 31.51% IACS, and the Brinell hardness (HB5) is 214.

Example 2:

The first step: mix W powder with a purity greater than 99.9% and an average particle size of 2 to 4 microns, and reduced Cu powder with a purity greater than 99.7% and an average particle size of 20 to 50 microns according to the mass percentage of W-3Cu, and use a planetary ball mill to The powder was mixed in the water-ethanol medium for 6 hours, the rotation speed was 150 rpm, and the ball-to-material ratio was 2:1.

The second step: adding 1% stearic acid as a forming agent to the mixed and dried powder to improve its compressibility. Weigh 9.78g of mixed powder and 2.02g of electrolytic copper powder with a purity of >99.7% and a particle size of 60-90 microns according to the W-20Cu composition, and press a cylindrical W skeleton with a diameter of φ18mm and an infiltrated Cu compact under a pressure of 460MPa.

Step 3: Place the pressed cylindrical W skeleton, infiltrated Cu compact and 120g of auxiliary heating material SiC sheet in the alumina fiber insulation sheath, place the infiltrated Cu compact on the top of the cylindrical W skeleton, and then place into the cavity of a microwave high-temperature furnace, and use a vacuum pump to pump the cavity to a vacuum of less than 100Pa;

Step 4: Introduce N ₂ , H ₂ gas volume ratio into the microwave oven cavity: N ₂ : _{H 2} = 90:10 N ₂ , H ₂ mixed protective gas, adjust the output power of the microwave high-temperature furnace, and set it at 30°C /min heating rate to 1350°C, keep warm for 20 minutes, turn off the microwave oven, and obtain the ideal alloy after cooling.

The performance parameters of the alloy obtained after cooling are: the relative density reaches 98.7%, the electrical conductivity is 32.15% IACS, and the Brinell hardness (HB5) is 217.

Example 3:

The first step: mix W powder with a purity greater than 99.9% and an average particle size of 2 to 4 microns, and reduced Cu powder with a purity greater than 99.7% and an average particle size of 20 to 50 microns according to the mass percentage of W-3Cu, and use a planetary ball mill to The powder was mixed in the water-ethanol medium for 5 hours, the rotation speed was 100 rpm, and the ball-to-material ratio was 2:1.

The second step: adding 0.5% stearic acid as a forming agent to the mixed and dried powder to improve its compressibility. Weigh 8.82g of mixed powder and 2.5g of electrolytic copper powder with a purity of >99.7% and a particle size of 60-90 microns according to the W-25Cu composition, and press them under a pressure of 150MPa to form cylindrical W skeletons with a diameter of φ18mm and infiltrated Cu compacts.

Step 3: Place the pressed cylindrical W skeleton, infiltrated Cu compact and 100g of auxiliary heating material SiC sheet in the alumina fiber insulation sheath, place the infiltrated Cu compact on the top of the cylindrical W skeleton, and then place into the cavity of a microwave high-temperature furnace, and use a vacuum pump to pump the cavity to a vacuum of less than 100Pa;

Step 4: Introduce N ₂ and H ₂ mixed protective gas with N ₂ and H ₂ gas volume ratio: N ₂ : _{H 2} =95:5 into the cavity of the microwave oven, and adjust the output power of the microwave oven at 25°C /min heating rate to 1300°C, keep warm for 15 minutes, turn off the microwave oven, and obtain the ideal alloy after cooling.

The performance parameters of the alloy obtained after cooling are: the relative density reaches 98.7%, the electrical conductivity is 43.03% IACS, and the Brinell hardness (HB5) is 196.

Claims (6)

1. the method for a preparing W-Cu alloy in microwave infiltration way comprises following processing step:

The first step: with purity greater than 99.9%, the W powder of 2 ~ 4 microns of mean particle sizes and purity greater than 99.7%, the reduction Cu powder of 20 ~ 50 microns of the mean particle sizes mass percent batching of pressing W-3Cu, ball milling mixes 5～7h;

Second step: add 0.5～1.5% stearic acid in the powder that combination drying is good and make binder, to improve its compactibility, press design mix, get powder mix and purity＞99.7%, the electrolytic copper powder that granularity is 60 ~ 90 microns is suppressed cylinder W skeleton and infiltration cu pressed compact respectively under the pressure of 150 ~ 510MPa;

The 3rd step: cylinder W skeleton, infiltration cu pressed compact and the boosting material SiC sheet that suppresses placed in the sapphire whisker insulation jacket, then, put into microwave high-temperature stove furnace chamber, and furnace chamber is evacuated in the vacuum tightness 100Pa with vacuum pump;

The 4th step: in micro-wave oven furnace chamber, feed N ₂H ₂Hybrid protection gas is regulated microwave high-temperature stove output rating, is heated to 1300～1400 ℃ with the heat-up rate of 25～35 ℃/min, is incubated 15～25 minutes, closes microwave oven, promptly obtains the ideal alloy after the cooling.

2. the method for a kind of preparing W-Cu alloy in microwave infiltration way according to claim 1 is characterized in that: described ball milling mixes and adopts planetary ball mill, and ball-milling medium is a dehydrated alcohol, and rotating speed is 100～200rpm, ratio of grinding media to material 2: 1.

3. the method for a kind of preparing W-Cu alloy in microwave infiltration way according to claim 1, it is characterized in that: described boosting material SiC sheet addition is 100～140g.

4. the method for a kind of preparing W-Cu alloy in microwave infiltration way according to claim 1 is characterized in that: described N ₂H ₂N in the hybrid protection gas ₂H ₂The gas volume ratio is: N ₂: H ₂=(85～95): (5～15).

5. the method for a kind of preparing W-Cu alloy in microwave infiltration way according to claim 1 is characterized in that: described infiltration cu pressed compact is placed on cylinder W skeleton top integral body and places in the sapphire whisker insulation jacket.

6. the method for a kind of preparing W-Cu alloy in microwave infiltration way according to claim 1, it is characterized in that: the Cu powder is an inductor in the described W-3Cu mixed powder.