CN101288905A - Preparation method of copper-coated tungsten composite powder - Google Patents

Abstract

The invention discloses a preparation method of copper-coated tungsten composite powder, which comprises taking tungsten powder and copper sulfate pentahydrate according to the required quality; moistening the tungsten powder with 37% to 40% formaldehyde solution; Make a solution with a concentration of 12.8g/L, then add disodium edetate and sodium methyl tartrate, the concentrations are 27.3g/L and 13.6g/L respectively, to obtain a mixed solution, and add wet tungsten powder to the mixed solution , feed compressed air with a flow rate of 0.6L/min to 1.0L/min, stir, control the pH value of the solution to 11 to 13, and heat until the tungsten powder turns purple; let stand for 15 to 20 minutes, separate the supernatant and The precipitated powder is treated with hydrochloric acid and benzotriazole ethanol solution at 45°C to 55°C, and reduced for 2h to 4h in a reduction furnace at 300°C to 320°C with a hydrogen flow rate of 2.0 to 2.5L/min, namely A copper-coated tungsten composite powder is obtained. The method of the invention can prepare composite materials with high density, high thermal conductivity, high electrical conductivity and low expansion coefficient.

Description

Preparation method of copper-coated tungsten composite powder

technical field

The invention belongs to the technical field of material preparation, and relates to a method for preparing a coated composite powder, in particular to a method for preparing a copper-coated tungsten composite powder.

Background technique

As a functional material, powder plays an extremely important role in the compounding and development of new materials. Research has found that a high-performance composite powder material can be obtained by surface coating or composite treatment of two or more powder particles. Composite powder not only has the performance of a single powder, but also has the functions of compound synergy, multi-functionality, changing the surface properties of a single particle, and increasing the contact area of two or more components. It is widely used in military, aviation, aerospace, chemical, medicine and other fields.

With the emergence and application of powder technology, the powder coating modification technology has been developed. The principle is to uniformly introduce one or more other components on the surface of the original powder particles to form a certain thickness of adsorption. Layer or monolayer film, so as to change the surface characteristics of the powder or endow the powder with new properties. Coating technology plays an important role in improving the dispersion performance of powder, solving its agglomeration problem, improving the activity, optical properties, heat resistance, light resistance, surface color and even subsequent sintering characteristics of powder particles.

Tungsten powder has the characteristics of high melting point, high density, high hardness, low saturated vapor pressure, and small thermal expansion coefficient. Electroless copper plating on the surface of tungsten powder can improve the processing performance and thermal conductivity of tungsten, as well as the compression molding of tungsten powder or other materials during powder metallurgy. Performance, at present, there is no mature technology of copper-coated tungsten powder in China, only mechanical mixing and alloying of copper powder and tungsten powder, or chemical co-precipitation of tungsten salt and copper salt to obtain a composite with uniform distribution of copper and tungsten Powder.

Contents of the invention

The purpose of the present invention is to provide a preparation method of copper-coated tungsten composite powder, which can coat a layer of copper film on the surface of tungsten powder and broaden the application range of tungsten powder.

The technical solution adopted in the present invention is a preparation method of copper-coated tungsten composite powder, which is carried out according to the following steps:

Step 1: According to the weight of tungsten in the copper-coated tungsten composite powder to be prepared, take tungsten powder with a particle size of 1 μm to 1 mm, and add formaldehyde solution with a concentration of 37% to 40% to the tungsten powder to obtain wet Tungsten powder, control the volume-to-mass ratio of formaldehyde solution to tungsten powder to be 0.7ml/g～0.8ml/g;

Step 2: According to the weight of copper in the copper-coated tungsten composite powder to be prepared, take copper sulfate pentahydrate 5.47 times the weight of copper;

Step 3: add distilled water in the copper sulfate pentahydrate that gets in step 2, be made into the copper sulfate solution that concentration is 12.8g/L, then, slowly add disodium edetate in this copper sulfate solution, control ethyl The concentration of disodium diamine tetraacetate in the solution is 27.3g/L, then add sodium methyl tartrate, control the concentration of sodium methyl tartrate in the solution to be 13.6g/L, stir while adding the two solutions, mix evenly , to obtain a mixed solution;

Step 4: Mix the wet tungsten powder obtained in step 1 with the mixed solution obtained in step 3 to obtain a cloudy solution;

Step 5: Introduce compressed air with a flow rate of 0.6L/min to 1.0L/min into the turbid solution obtained in step 4, and stir vigorously. At the same time, add NaOH solution with a concentration of 10% to the turbid solution to control the turbidity The pH value of the liquid is 11-13, and the cloudy liquid is heated until the blue color of the cloudy liquid disappears, and the tungsten powder turns purple, at this time, stop heating and stirring;

Step 6: Leave the turbid solution after the previous step for 15 to 20 minutes, separate the supernatant from the precipitated powder, add 36% to 38% hydrochloric acid to the powder, and the volume ratio of hydrochloric acid to powder is 1: 1, then stand still, then separate the clear liquid and precipitated powder from the hydrochloric acid and powder mixture, wash the above hydrochloric acid-treated powder with distilled water and filter;

Step 7: Add benzotriazole ethanol solution at a temperature of 45°C to 55°C to the powder cleaned in step 6, stir and soak for 5min to 8min, passivate the powder, and then wash the powder with distilled water and absolute ethanol respectively, filter;

Step 8: Dry the powder treated in step 7 in the air, then put it into a hydrogen reduction furnace with a temperature of 300°C-320°C and a hydrogen flow rate of 2.0L/min-2.5L/min, and reduce it for 2h-4h , that is, the copper-coated tungsten composite powder is obtained.

The beneficial effect of the present invention is to further improve the uniformity of the tungsten-copper composite powder and the comprehensive performance of the material, solve the problem of segregation of the copper phase during the sintering and molding process of the composite powder, and make the copper phase uniformly distributed in the form of a network in the tungsten matrix around. Furthermore, a composite material with high density, high thermal conductivity, high electrical conductivity and low expansion coefficient is obtained, and copper-coated tungsten powder is prepared by the method of the present invention, which has the characteristics of low energy consumption, short production cycle, high purity and the like.

Detailed ways

The present invention will be described in detail below in combination with specific embodiments.

The preparation method of the present invention comprises the following steps:

Step 1: Calculate the weight of required tungsten and copper according to the weight of the tungsten-copper composite powder to be prepared, and the weight percentage (CuxWy, where x+y=100%) of tungsten and copper in the composite powder, and then According to the following chemical formula CuSO ₄ 5H ₂ O-Cu, according to the ratio of the atomic weight of copper in the atomic weight of anhydrous copper sulfate and the weight of the copper obtained above, calculate the required amount of copper sulfate pentahydrate (CuSO ₄ 5H ₂ O) Weight, in the actual operation process, copper loss occurs, for this reason, the correction coefficient k ₁ =1.3～1.5 is used to correct the weight value of copper sulfate pentahydrate, that is, the required weight of copper sulfate pentahydrate is 5.47x;

Step 2: According to the weight of the tungsten powder calculated in step 1, take the tungsten powder with a particle size of 1 μm ~ 1mm, and then take the formaldehyde solution with a concentration of 37% ~ 40%, pour the tungsten powder into the tungsten powder, make the tungsten powder wet, and control The volume-mass ratio of formaldehyde solution to tungsten powder is 0.7ml/g～0.8ml/g;

Step 3: according to the weight of copper sulfate pentahydrate obtained in step 1, get copper sulfate pentahydrate (CuSO _{5H 2} O), add distilled water, obtain copper sulfate solution, control the concentration of copper sulfate in this solution to be 12.8g/L , then slowly add disodium edetate to the copper sulfate solution, control the concentration of disodium edetate in the solution to be 27.3g/L, methyl sodium tartrate, control the concentration of sodium methyl tartrate in the solution The concentration is 13.6g/L, slowly add the above two solutions while stirring, and mix evenly to obtain a mixed solution;

Step 4: Mix the wet tungsten powder obtained in step 2 with the mixed solution obtained in step 3 to obtain a cloudy solution;

Step 5: Put compressed air into the turbid liquid prepared in the previous step, and control the air flow rate to 0.6L/min～1.0L/min. At the same time, stir the turbid liquid with a stirrer to suspend the tungsten powder, and Add 10% NaOH solution dropwise to the turbid liquid to control the pH value of the turbid liquid to 11-13. At the same time, heat the turbid liquid until the blue color of the turbid liquid disappears, and the gray-black tungsten powder Turn into purple, that is, stop heating, stirring, passing compressed air and adding NaOH solution dropwise;

Step 6: Put the turbid liquid that completed the chemical reaction in the previous step to stand still for 15 to 20 minutes, pour off the supernatant, and then add hydrochloric acid with a concentration of 36% to 38% to the precipitated powder at a volume ratio of 1:1, and then Set aside to settle, and pour off the excess liquid in the upper layer. After that, add distilled water to the powder that has been treated with hydrochloric acid and precipitated. The amount of distilled water added is just enough to cover the powder, then wash, filter, and wash repeatedly 2 to 3 times;

Step 7: Add the ethanol solution of benzotriazole at a temperature of 45°C to 55°C to the powder obtained in the previous step, the volume of the solution just covers the powder, stir and soak for 5min to 8min to passivate it, and then wash it with distilled water 4 to 6 times, then wash 2 to 3 times with absolute ethanol and filter, the volume of liquid added in each wash is just enough to cover the powder;

Step 8: Put the powder after the passivation treatment in the previous step to dry in the air, and then put the powder into a hydrogen reduction furnace at a temperature of 300°C to 320°C, with a flow rate of 2.0L/min to 2.5L/min Min hydrogen, reduction 2h ~ 4h, that is the preparation of copper-coated tungsten composite powder.

Example 1

100g of tungsten-copper composite powder needs to be prepared, and the content of each component is 85% of tungsten and 15% of copper by weight percentage.

Take 85 grams of tungsten powder with a particle size of 10 μm, add a formaldehyde solution with a concentration of 37% to the tungsten powder, control the volume-to-mass ratio of the formaldehyde solution to the tungsten powder to be 0.7ml/g, and wet the tungsten powder. Calculated according to the ratio and correction coefficient, take 82.0 g of copper sulfate pentahydrate, add distilled water, and make a copper sulfate solution with a concentration of 12.8 g/L. Slowly add disodium edetate 111.9g respectively in this copper sulfate solution, control the concentration of disodium edetate in the solution to be 27.3g/L, methyl sodium tartrate 55.8g, control sodium methyl tartrate in the solution The concentration of the mixture is 13.6g/L, and at the same time, it is stirred and mixed evenly to form a mixed solution. Add this mixture to wet tungsten powder to form a cloudy solution. Pass compressed air into the cloudy liquid, and control the air flow rate to 0.6L/min; use an electric stirrer to vigorously stir the cloudy liquid to suspend the tungsten powder to form a suspension, and heat the suspension at the same time, 10% NaOH solution was added dropwise into the suspension to control the pH value of the suspension to 11 during the reaction. When the temperature of the suspension reaches 60°C, the copper plating reaction proceeds rapidly, the blue color of the plating solution disappears, the tungsten powder turns purple, and the copper plating reaction is completed. At this time, stop heating, stirring and feeding compressed air. The suspension that has completed the chemical reaction is left to stand for 15 minutes, the supernatant is removed, and a 36% hydrochloric acid solution is added to the remaining precipitate at a volume ratio of 1:1 to neutralize excess lye, Then let it stand, settle and pour off the excess solution, add distilled water to the precipitate, and wash the precipitate, the amount of water added is just enough to cover the composite powder, then filter, and wash repeatedly 3 times. Then add the ethanol solution of benzotriazole at a temperature of 45°C to the washed precipitate, stir and soak for 5 minutes to passivate it. After that, wash 6 times with distilled water, wash 3 times with absolute ethanol and filter, add the liquid volume just enough to cover the powder each time. Dry the above-mentioned cleaned precipitate in the shade in the air, and place it in a reduction furnace at a temperature of 300°C, pass in hydrogen gas with a flow rate of 2L/min, and reduce for 2 hours to obtain a copper-coated tungsten composite powder.

Example 2

200g of tungsten-copper composite powder needs to be prepared, and the content of each component is 80% tungsten and 20% copper according to mass percentage.

Take 160 grams of tungsten powder with a particle size of 6 μm, add a formaldehyde solution with a concentration of 38% to the tungsten powder, control the volume to mass ratio of the formaldehyde solution to the tungsten powder to be 0.73ml/g, and wet the tungsten powder. According to the ratio and correction coefficient calculation, take 218.8g of copper sulfate pentahydrate, add 11.0L of distilled water, and make a copper sulfate solution with a concentration of 12.8g/L. Slowly add disodium edetate 300.3g respectively in this copper sulfate solution, control the concentration of disodium edetate in the solution to be 27.3g/L, sodium methyl tartrate 149.6g, control sodium methyl tartrate in the solution The concentration of the mixture is 13.6g/L, and at the same time, it is stirred and mixed evenly to form a mixed solution. Add this mixture to wet tungsten powder to form a cloudy solution. Pass compressed air into the cloudy liquid, and control the air flow rate to 0.7L/min; use an electric stirrer to vigorously stir the cloudy liquid to suspend the tungsten powder to form a suspension, and heat the suspension at the same time, 10% NaOH solution was added dropwise to the suspension to control the pH of the suspension to 11.5 during the reaction. When the temperature of the suspension reaches 60°C, the copper plating reaction proceeds rapidly, the blue color of the plating solution disappears, the tungsten powder turns purple, and the copper plating reaction is completed. At this time, stop heating, stirring and feeding compressed air. The suspension that has completed the chemical reaction is left to stand for 16 minutes, the supernatant is removed, and a 36.5% hydrochloric acid solution is added to the remaining precipitate at a volume ratio of 1:1 to neutralize excess lye, Then let it stand, settle and pour off the excess solution, add distilled water to the precipitate, and wash the precipitate, the amount of water added is just enough to cover the composite powder, then filter, and wash repeatedly 3 times. Then add benzotriazole ethanol solution at 47°C to the precipitate, stir and soak for 6 minutes to passivate it. Afterwards, the passivated precipitate was washed 6 times with distilled water, 3 times with absolute ethanol and filtered, and the volume of liquid added each time was just enough to cover the powder. Dry the above-mentioned cleaned precipitate in the air, place it in a reduction furnace at a temperature of 305°C, and pass in hydrogen gas with a flow rate of 2.2L/min, and reduce it for 2.5 hours to obtain a copper-coated tungsten composite powder.

Example 3

It is necessary to prepare 500g of tungsten-copper composite powder. According to mass percentage, the content of each component is 90% tungsten and 10% copper.

Take 450 grams of tungsten powder with a particle size of 4 μm, add formaldehyde solution with a concentration of 39% to the tungsten powder, control the volume to mass ratio of the formaldehyde solution to the tungsten powder to be 0.75ml/g, and wet the tungsten powder. According to the ratio and correction coefficient calculation, take 273.5g of copper sulfate pentahydrate, add 13.7L of distilled water, and make a copper sulfate solution with a concentration of 12.8g/L. Slowly add disodium edetate 374.0g respectively in this copper sulfate solution, control the concentration of disodium edetate in the solution to be 27.3g/L, sodium methyl tartrate 186.3g, control sodium methyl tartrate in the solution The concentration of the mixture is 13.6g/L, and at the same time, it is stirred and mixed evenly to form a mixed solution. Add this mixture to wet tungsten powder to form a cloudy solution. Pass compressed air into this turbid liquid, and control the air flow rate to be 0.8L/min. Use an electric stirrer to vigorously stir the turbid solution to suspend the tungsten powder to form a suspension. At the same time, the suspension is heated, and 10% NaOH solution is added dropwise to the suspension to control the reaction process. The pH of the suspension was 12. When the temperature of the suspension reaches 60°C, the copper plating reaction proceeds rapidly, the blue color of the plating solution disappears, the tungsten powder turns purple, and the copper plating reaction is completed. At this time, stop heating, stirring and feeding compressed air. The suspension that has completed the chemical reaction is left to stand for 18 minutes, the supernatant is removed, and a 37% hydrochloric acid solution is added to the remaining precipitate at a volume ratio of 1:1 to neutralize excess lye. Then let it stand, settle and pour off the excess solution, add distilled water to the precipitate, and wash the precipitate, the amount of water added is just enough to cover the composite powder, then filter, and wash repeatedly 3 times. Then add benzotriazole ethanol solution at a temperature of 48°C to the precipitate, stir and soak for 7 minutes to passivate it. Afterwards, the passivated precipitate was washed 6 times with distilled water, 3 times with absolute ethanol and filtered, and the volume of liquid added each time was just enough to cover the powder. Dry the above-mentioned washed precipitate in the air, place it in a reduction furnace at a temperature of 310°C, pass in hydrogen gas with a flow rate of 2.3L/min, and reduce it for 3 hours to obtain a copper-coated tungsten composite powder.

Example 4

1000g of tungsten-copper composite powder needs to be prepared, and the content of each component is 70% of tungsten and 30% of copper according to mass percentage.

Take 700 grams of tungsten powder with a particle size of 15 μm, add formaldehyde solution with a concentration of 40% to the tungsten powder, control the volume-mass ratio of formaldehyde solution to tungsten powder to 0.78ml/g, and wet the tungsten powder. According to the ratio and correction coefficient calculation, take 1641.0 g of copper sulfate pentahydrate, add 82.0 L of distilled water, and make a copper sulfate solution with a concentration of 12.8 g/L. Slowly add 2238.6 g of disodium ethylenediamine tetraacetate to the copper sulfate solution, the control concentration is 27.3 g/L, 1115.2 g of sodium methyl tartrate, the control concentration is 13.6 g/L, stir at the same time, mix well, and form a mixed solution . Add this mixture to wet tungsten powder to form a cloudy solution. Pass compressed air into this turbid liquid, and control the air flow rate to be 0.9L/min. Use an electric stirrer to vigorously stir the turbid solution to suspend the tungsten powder to form a suspension. At the same time, the suspension is heated, and 10% NaOH solution is added dropwise to the suspension to control the reaction process. The pH of the suspension was 12.5. When the temperature of the suspension reaches 60°C, the copper plating reaction proceeds rapidly, the blue color of the plating solution disappears, the tungsten powder turns purple, and the copper plating reaction is completed. At this time, stop heating, stirring and feeding compressed air. The suspension that has completed the chemical reaction is left to stand for 19 minutes, the supernatant is removed, and a 38% hydrochloric acid solution is added to the remaining precipitate at a volume ratio of 1:1 to neutralize excess lye. Then let it stand, settle and pour off the excess solution, add distilled water to the precipitate, and wash the precipitate, the amount of water added is just enough to cover the composite powder, then filter, and wash repeatedly 3 times. Then add benzotriazole ethanol solution at a temperature of 49°C to the precipitate, stir and soak for 8 minutes to passivate it. Afterwards, the passivated precipitate was washed 6 times with distilled water, 3 times with absolute ethanol and filtered, and the volume of liquid added each time was just enough to cover the powder. Dry the above-mentioned cleaned precipitate in the air, and place it in a reduction furnace at a temperature of 315°C, pass in hydrogen gas with a flow rate of 2.4L/min, and reduce for 3.5h to obtain a copper-coated tungsten composite powder.

Example 5

It is necessary to prepare 1000g of tungsten-copper composite powder, and the content of each component is 50% of tungsten and 50% of copper according to the mass percentage.

Take 500 grams of tungsten powder with a particle size of 20 μm, add formaldehyde solution with a concentration of 40% to the tungsten powder, control the volume to mass ratio of the formaldehyde solution to the tungsten powder to be 0.8ml/g, and wet the tungsten powder. According to the ratio and correction coefficient calculation, take 2735.0 g of anhydrous copper sulfate, add 137.0 L of distilled water, and make a copper sulfate solution with a concentration of 12.8 g/L. Slowly add 3740.0 g of disodium ethylenediamine tetraacetate to the copper sulfate solution, the control concentration is 27.3 g/L, 1863.0 g of sodium methyl tartrate, the control concentration is 13.6 g/L, stir at the same time, mix well, and form a mixed solution . Add this mixture to wet tungsten powder to form a cloudy solution. Pass compressed air into the turbid liquid, and control the air flow rate to 1.0 L/min. Use an electric stirrer to vigorously stir the turbid solution to suspend the tungsten powder to form a suspension. At the same time, the suspension is heated, and 10% NaOH solution is added dropwise to the suspension to control the reaction process. The pH of the suspension was 13. When the temperature of the suspension reaches 60°C, the copper plating reaction proceeds rapidly, the blue color of the plating solution disappears, the tungsten powder turns purple, and the copper plating reaction is completed. At this time, stop heating, stirring and feeding compressed air. The suspension that has completed the chemical reaction is left to stand for 20 minutes, the supernatant is removed, and a 38% hydrochloric acid solution is added to the remaining precipitate at a volume ratio of 1:1 to neutralize excess lye, Then let it stand, settle and pour off the excess solution, add distilled water to the precipitate, and wash the precipitate, the amount of water added is just enough to cover the composite powder, then filter, and wash repeatedly 3 times. Then add benzotriazole ethanol solution at a temperature of 55°C to the precipitate, stir and soak for 8 minutes to passivate it. Afterwards, the passivated precipitate was washed 6 times with distilled water and 3 times with absolute ethanol and filtered, and the volume of the liquid added each time was just enough to cover the powder. Dry the above-mentioned washed precipitate in the air, place it in a reduction furnace at a temperature of 320°C, pass in hydrogen gas with a flow rate of 2.5L/min, and reduce it for 4 hours to obtain a copper-coated tungsten composite powder.

The following table is a comparison of the physical properties of the alloys prepared by using the copper-coated tungsten composite powder prepared by the method of the present invention and the copper-tungsten composite powder prepared by the prior art as raw materials (composition; Cu20W80).

surface

The above table shows that the thermal conductivity, hardness and other physical properties of the alloy prepared by the copper-coated tungsten composite powder prepared by the method of the present invention are significantly better than those prepared by using the copper-tungsten composite powder prepared by the prior art as raw materials.

Claims (1)

1. the preparation method of a copper cladding tungsten composite powder is characterized in that, carries out according to the following steps:

Step 1: according to the weight of tungsten in the copper cladding tungsten composite powder of required preparation, get the tungsten powder that particle diameter is 1 μ m～1mm, get concentration and be 37%～40% formalin and add in this tungsten powder, obtain moistening tungsten powder, the volume mass of control formalin and tungsten powder is than being 0.7ml/g～0.8ml/g;

Step 2:, get the cupric sulfate pentahydrate of 5.47 times of weight of weight of copper according to the weight of copper in the copper cladding tungsten composite powder of required preparation;

Step 3: in the cupric sulfate pentahydrate that step 2 is got, add distilled water, be made into the copper-bath that concentration is 12.8g/L, then, slowly add disodium ethylene diamine tetraacetate in this copper-bath, the concentration of control disodium ethylene diamine tetraacetate in solution is 27.3g/L, adds tartaric acid first sodium again, the concentration of control tartaric acid first sodium in solution is 13.6g/L, stir when adding these two kinds of solution, evenly mix, obtain mixed solution;

Step 4: the moistening tungsten powder that step 1 is obtained mixes with the mixed solution that step 3 obtains, and obtains muddy liquid;

Step 5: feeding flow in the muddy liquid that step 4 obtains is 0.6L/min～1.0L/min compressed air, and strong agitation, simultaneously, dropping concentration is 10% NaOH solution in this muddiness liquid, and the pH value of controlling muddy liquid is 11～13, and to this muddy liquid heating, blueness to muddy liquid disappears, tungsten powder becomes aubergine, at this moment, stops heating and stirring;

Step 6: the muddy liquid that will go up after the step handles left standstill 15 minutes～20 minutes, powder separation with supernatant liquor and precipitation, in this powder, add 36%～38% hydrochloric acid, the volume ratio of hydrochloric acid and powder is 1: 1, leave standstill then, to isolate the powder of clear liquid and precipitation in hydrochloric acid and the powder body again, clean the powder and the filtration of above-mentioned salt acid treatment with distilled water;

Step 7: the adding temperature is 45 ℃～55 ℃ a benzotriazole ethanolic solution in the powder after step 6 cleaning, stirs and soaks 5min～8min, and the passivation powder is used the cleaning of distilled water and absolute ethyl alcohol, filtration respectively with this powder again;

Step 8: the powder with after step 7 processing, place air to dry in the shade, putting into temperature then is 300 ℃～320 ℃, and hydrogen flowing quantity is in the hydrogen reducing furnace of 2.0L/min～2.5L/min, and reductase 12 h～4h promptly makes copper cladding tungsten composite powder.