CN103418786A - Preparation method of W-Cu-Ni alloy material with low W-W connectivity - Google Patents

Abstract

The invention discloses a preparation method of a W-Cu-Ni alloy material with low W-W connectivity. The specific process includes the steps that a nickel coating layer is arranged on the surface of micro order tungsten powder in a plating mode through a chemical plating method, the tungsten powder with the surface coated with the nickel layer and copper powder are dispensed and mixed, then spark plasma sintering is conducted on the evenly-mixed powder, and the W-Cu-Ni alloy material with the high density and low W-W connectivity can be prepared. The preparation method of the W-Cu-Ni alloy material with the low W-W connectivity has the advantages that first, the nickel coating layer can improve the interface bonding strength of a tungsten phase and a copper phase, the activated sintering function is further achieved, sintering temperatures are lowered, and meanwhile the density of the material can be better improved; second, by means of the preparation method, the W-Cu-Ni alloy material with the density being larger than 97.5% and the low W-W connectivity being smaller than 30% can be prepared, and the material has excellent tensile mechanical performance. The W-Cu-Ni alloy material has excellent mechanical performance, and is suitable for the fields of aviation and weapons.

Description

A kind of preparation method of low W-W connection degree W-Cu-Ni alloy material

technical field

The invention belongs to the technical field of metallurgy, and relates to a preparation process of refractory metals, in particular to a preparation method of a W-Cu-Ni alloy with a low W-W connection degree.

Background technique

Tungsten copper alloy material not only has the characteristics of high strength, high hardness and low expansion coefficient of tungsten, but also has high electrical conductivity, thermal conductivity and good plasticity of copper, so it is widely used in aerospace, EDM and electronic packaging materials, etc. field. With the development of science and technology, tungsten-copper alloys also show good application potential as warhead materials, but at the same time, higher requirements are placed on the mechanical properties of tungsten-copper alloys, especially the tensile mechanical properties of materials.

For tungsten-copper alloys, its failure methods include cracking at the W-W interface, cracking at the W-Cu interface, cleavage fracture of W particles, and tearing of the bonding phase. Due to the weak bonding strength of the W-W interface in tungsten-copper alloys, there is no metallurgical gap between W-Cu. Combination, the bonding strength is also very weak, so the W-W interface and W-Cu interface are easy to crack under tensile loading conditions, resulting in extremely poor tensile strength of tungsten-copper alloy. Therefore, in order to improve the tensile strength of tungsten-copper alloys, the formation of the W-W interface must be suppressed first, the W-W connection degree should be reduced, and at the same time, the metallurgical bonding between W-Cu should be realized to increase the bonding strength of the W-Cu interface.

At present, there are already methods to solve the problem of high W-W connectivity. For example, Chinese patent ZL201010607044.2 provides a preparation method of copper-coated tungsten composite powder. The tungsten alloy prepared by sintering the copper-coated tungsten powder prepared by this method avoids the direct contact of W-W, but the bonding strength of the W-Cu interface remains the same. Not improved. Therefore, how to improve the bonding strength of the W-Cu interface while reducing the W-W connectivity in the W-Cu alloy, and further improve the tensile mechanical properties of the material has become an urgent problem to be solved.

Since Ni and Cu are completely miscible to form an infinite solid solution, and W can partially dissolve to form a limited solid solution, it is possible to coat the Ni layer on the surface of W particles and mix it with copper powder, and then use spark plasma sintering (SPS) to prepare tungsten-copper-nickel Alloy, improve the tensile strength of tungsten copper alloy. In this preparation method, a solid solution is formed between the Ni layer and the W phase and the copper phase, which can improve the metallurgical bonding force between the W-Cu interface, thereby improving the strength of the W-Cu interface. The direct contact between them reduces the W-W connectivity. In addition, Ni and Cu form a solid solution, which plays a role of solid solution strengthening and improves the strength of the alloy. Therefore, a high-density tungsten-copper alloy material with good W-Cu interface bonding strength, low W-W connectivity and good tensile mechanical properties can be prepared by the above method.

Contents of the invention

The tungsten-based alloy involved in the present invention is a W-Cu-Ni alloy material.

The invention improves the tensile properties of the existing tungsten-copper alloys, and provides a combination of electroless nickel plating and spark plasma sintering, which has higher W-Cu interface bonding strength, low W-W connectivity, high density, and better tensile strength. The preparation method of W-Cu-Ni alloy material with ductility.

The technical solution adopted by the present invention is: coating a layer of nickel on the surface of tungsten particles by electroless nickel plating, mixing nickel-coated tungsten powder and copper powder evenly by mechanical mixing, and using spark plasma sintering equipment to mix evenly The powder is sintered to obtain a W-Cu-Ni alloy with high density, low W-W connectivity and fine grains. The calculation formula of W-W connection degree in W-Cu-Ni alloy is:

${\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; SS</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; SS</span>}}}{{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; SS</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; SL</span>}}}$

In the formula, C _SS is the WW connectivity, N _SS is the number of WW interfaces, and N _SL is the number of W-Cu interfaces. The calculation method of N _SS and N _SL is as follows: draw a grid on the cross-sectional topography of W-Cu-Ni alloy, and then count the number of WW interfaces and W-Cu interfaces that the line passes through along the horizontal line (vertical line) Count until all the intersection points of the horizontal lines (vertical lines) and the WW interface and the W-Cu interface are counted, and the corresponding intersection points are N _SS and N _SL respectively.

For the above electroless nickel plating process, the range of process parameters is as follows:

The concentration range of nickel sulfate hexahydrate is 20-40g/L, the concentration range of sodium hydrogen hypophosphite is 20-40g/L, the concentration range of ammonium chloride is 30-40g/L, the concentration range of sodium pyrophosphate is 50-70g/L, The concentration range of sodium citrate is 5-10g/L, the concentration range of triethanolamine is 90-120g/L, the temperature of the plating solution is 35-40°C, the pH value is 8-10, and the electroless plating time is 20-40min.

For the preparation method of above-mentioned W-Cu-Ni alloy material, comprise the steps:

(1) Prepare nickel-coated tungsten composite powder by electroless nickel plating, and then use planetary ball mill (without balls) to mix nickel-coated tungsten composite powder with a certain proportion of copper powder for 1 to 2 hours (wet mixing) , dried under vacuum conditions, the mass percentage of each element is: W content 65% ~ 80%, Cu content 15% ~ 25%, Ni content 5% ~ 10%.

(2) The uniformly mixed alloy element powder obtained in (1) is reduced in a hydrogen atmosphere for 0.5 to 1 hour, and the reduction temperature ranges from 200°C to 300°C to obtain a fully mixed mechanical mixture of metal powders without oxidation.

(3) Use spark plasma sintering technology to sinter the mixed powder obtained in (2), the sintering temperature is 850-950°C, the applied pressure is 20-50MPa, the heating rate is 50-150°C/min, and the holding time is 5-10min , The sintering atmosphere is vacuum protection.

Description of drawings

Fig. 1 is the overall morphology of nickel-coated tungsten composite powder;

Fig. 2 is the cross-sectional morphology of the nickel-coated tungsten composite powder inlaid with dental tray powder;

Figure 3 is the overall morphology of the low W-W connectivity W-Cu-Ni alloy;

Figure 4 is a partial enlarged morphology of the low W-W connectivity W-Cu-Ni alloy;

Figure 5 is the XRD pattern of the low W-W connectivity W-Cu-Ni alloy.

Detailed ways

The following five specific embodiments are used to illustrate and help further understanding of the present invention. However, the specific details of the examples are only for illustrating the present invention, and do not represent all the technical solutions under the concept of the present invention, so they should not be construed as limiting the technical solutions of the present invention. Some insubstantial changes that do not deviate from the concept of the present invention, such as simple changes or replacements with technical features having the same or similar technical effects, all fall within the protection scope of the present invention.

Example 1

A tungsten-copper-nickel alloy material, alloy composition and content (mass percentage): 80%W-15%Cu-5%Ni, and its preparation method includes the following steps:

Step 1: Select 20g of tungsten powder with an average particle size of 6μm, first use 60mL/L HCl to roughen and roughen for 12h, and then use 30g/LSnCl ₂ and 50mL/L HCl to sensitize. The sensitization uses ultrasound and stirring at the same time, and the time is 5min, and finally use 0.5g/LPdCl ₂ and 10mL/LHCl to activate, activate with ultrasound and stirring at the same time, the time is 100min;

Step 2: Weigh nickel sulfate hexahydrate according to the weight ratio of tungsten to nickel at 16:1, and prepare the plating solution as nickel sulfate hexahydrate 40g/L, sodium hypophosphite 30g/L, ammonium chloride 30g/L, sodium bicitrate 7g /L, sodium pyrophosphate 60g/L, triethanolamine 90g/L, the pH value of the plating solution is 8, the temperature is 35°C, the tungsten powder is uniformly dispersed in the plating solution by ultrasonic and stirring, and the stirring speed is 400r/min After the plating is completed, the surface of the tungsten powder is covered with a layer of 0.1μm thick nickel layer;

Step 3: Weigh copper powder with an average particle size of 1 μm according to the ratio of tungsten-copper-nickel content of 16:3:1, and wet-mix the tungsten powder and copper powder coated with nickel layer in a planetary ball mill (without balls) for 1 hour, and then Drying the mixed powder under vacuum;

Step 4, reducing the mixed powder obtained in step 3 in a hydrogen atmosphere for 0.5h, the reduction temperature is 200°C, to obtain a mechanical mixture of fully mixed and non-oxidized metal powder;

Step 5, put the metal powder mixture in step 4 into a graphite mold, and sinter it in a spark plasma sintering equipment. Protect.

The W-Cu-Ni alloy prepared by this method has a density of 97.55% and a W-W connection of 27%.

Example 2

A tungsten-copper-nickel alloy material, alloy composition and content (mass percentage): 75%W-20%Cu-5%Ni, and its preparation method includes the following steps:

Step 1: Select 20g of tungsten powder with an average particle size of 6μm, first use 60mL/L HCl to roughen and roughen for 12h, and then use 30g/LSnCl ₂ and 50mL/L HCl to sensitize. The sensitization uses ultrasound and stirring at the same time, and the time is 5min, and finally use 0.5g/LPdCl ₂ and 10mL/LHCl to activate, activate with ultrasound and stirring at the same time, the time is 100min;

Step 2: Weigh nickel sulfate hexahydrate according to the weight ratio of tungsten to nickel at 15:1, and prepare the plating solution as nickel sulfate hexahydrate 40g/L, sodium hypophosphite 30g/L, ammonium chloride 30g/L, sodium bicitrate 7g /L, sodium pyrophosphate 60g/L, triethanolamine 90g/L, the pH value of the plating solution is 8, the temperature is 35°C, the tungsten powder is uniformly dispersed in the plating solution by ultrasonic and stirring, and the stirring speed is 400r/min After the plating is completed, the surface of the tungsten powder is covered with a 0.2μm thick nickel layer;

Step 3: Weigh copper powder with an average particle size of 1 μm according to the ratio of tungsten-copper-nickel content of 15:4:1, wet-mix the tungsten powder and copper powder coated with nickel layer in a planetary ball mill (without balls) for 1 hour, and then Drying the mixed powder under vacuum;

Step 4, reducing the mixed powder obtained in step 3 in a hydrogen atmosphere for 0.5h, the reduction temperature is 200°C, to obtain a mechanical mixture of fully mixed and non-oxidized metal powder;

Step 5, put the metal powder mixture in step 4 into a graphite mold, and sinter it in a spark plasma sintering equipment. Protect.

The W-Cu-Ni alloy prepared by this method has a density of 97.65% and a W-W connection of 29%.

Example 3

A tungsten-copper-nickel alloy material, alloy composition and content (mass percentage): 70%W-25%Cu-5%Ni, and its preparation method includes the following steps:

Step 1: Select 20g of tungsten powder with an average particle size of 5μm, first use 60mL/L HCl to roughen and coarsen for 12h, and then use 30g/LSnCl ₂ and 50mL/L HCl to sensitize, and use ultrasound and stirring for sensitization at the same time. 5min, and finally use 0.5g/LPdCl ₂ and 10mL/LHCl to activate, activate with ultrasound and stirring at the same time, the time is 100min;

Step 2: Weigh nickel sulfate hexahydrate according to the weight ratio of tungsten to nickel at 14:1, and prepare the plating solution as nickel sulfate hexahydrate 30g/L, sodium hypophosphite 40g/L, ammonium chloride 30g/L, sodium bicitrate 10g /L, sodium pyrophosphate 50g/L, triethanolamine 120g/L, the pH value of the plating solution is 9, the temperature is 40°C, the tungsten powder is uniformly dispersed in the plating solution by ultrasonic and stirring, and the stirring speed is 350r/min After the plating is completed, the surface of the tungsten powder is covered with a layer of 0.3μm thick nickel layer;

Step 3: Weigh copper powder with an average particle size of 0.5 μm according to the content ratio of tungsten-copper-nickel 14:5:1, and wet-mix the nickel-coated tungsten powder and copper powder in a planetary ball mill (without balls) for 1.5 hours , and then dry the mixed powder under vacuum;

Step 4: Reducing the mixed powder obtained in Step 3 in a hydrogen atmosphere for 0.5 h at a reduction temperature of 240° C. to obtain a fully mixed mechanical mixture of metal powders without oxidation;

Step 5: Put the metal powder mixture in Step 4 into a graphite mold, and sinter in a spark plasma sintering equipment. Protect.

The density of W-Cu-Ni alloy prepared by this method is 97.51%, and the degree of W-W connection is 26%.

Example 4

A tungsten-copper-nickel alloy material, alloy composition and content (mass percentage): 65%W-25%Cu-10%Ni, and its preparation method includes the following steps:

Step 1: Select 20g of tungsten powder with an average particle size of 4μm, first use 60mL/L HCl to roughen and roughen for 12h, and then use 30g/LSnCl ₂ and 50mL/L HCl to sensitize. The sensitization uses ultrasound and stirring at the same time, and the time is 5min, and finally use 0.5g/LPdCl ₂ and 10mL/LHCl to activate, activate with ultrasound and stirring at the same time, the time is 100min;

Step 2: Weigh nickel sulfate hexahydrate according to the weight ratio of tungsten to nickel of 13:2, and prepare the plating solution with nickel sulfate hexahydrate 20g/L, sodium hypophosphite 20g/L, ammonium chloride 40g/L, sodium bicitrate 5g /L, sodium pyrophosphate 70g/L, triethanolamine 100g/L, the pH value of the plating solution is 10, the temperature is 35°C, the tungsten powder is uniformly dispersed in the plating solution by ultrasonic and stirring, and the stirring speed is 300r/min After the plating is completed, the surface of the tungsten powder is covered with a layer of 0.4μm thick nickel layer;

Step 3: Weigh copper powder with an average particle size of 1 μm according to the ratio of tungsten-copper-nickel content of 13:5:2, and wet-mix the tungsten powder and copper powder coated with nickel layer in a planetary ball mill (without balls) for 2 hours, and then Drying the mixed powder under vacuum;

Step 4, reducing the mixed powder obtained in Step 3 in a hydrogen atmosphere for 0.75h, the reduction temperature is 270°C, to obtain a mechanical mixture of fully mixed and non-oxidized metal powder;

Step 5: Put the metal powder mixture in step 4 into a graphite mold, and sinter in a spark plasma sintering equipment. The sintering temperature is 850°C, the holding time is 10min, the heating rate is 50°C/min, and the applied pressure is 40MPa. Protect.

The W-Cu-Ni alloy prepared by this method has a density of 97.85% and a W-W connection of 28%.

Example 5

A tungsten-copper-nickel alloy material, alloy composition and content (mass percentage): 65%W-25%Cu-10%Ni, and its preparation method includes the following steps:

Step 1: Select 20g of tungsten powder with an average particle size of 4μm, first use 60mL/LHCl to roughen for 12h, then use 30g/LSnCl2 and 50mL/LHCl for sensitization, use ultrasound and stirring at the same time for 5min, and finally Use 0.5g/LPdCl2 and 10mL/LHCl to activate, and activate with ultrasonic and stirring at the same time, and the time is 100min;

Step 2, take nickel sulfate hexahydrate by weighing tungsten-nickel weight ratio 13:2, prepare plating solution composition to be nickel sulfate hexahydrate 30g/L, sodium hypophosphite 30g/L, ammonium chloride 35g/L, sodium bicitrate 7g /L, sodium pyrophosphate 60g/L, triethanolamine 100g/L, the pH value of the plating solution is 10, the temperature is 35°C, the tungsten powder is uniformly dispersed in the plating solution by ultrasonic and stirring, and the stirring speed is 300r/min After the plating is completed, the surface of the tungsten powder is covered with a layer of 0.4μm thick nickel layer;

Step 3: Weigh copper powder with an average particle size of 0.5 μm according to the ratio of tungsten-copper-nickel content of 13:5:2, and wet-mix the nickel-coated tungsten powder and copper powder in a planetary ball mill (without balls) for 2 hours, The mixed powder is then dried under vacuum;

Step 4, reducing the mixed powder obtained in step 3 in a hydrogen atmosphere for 1 hour, the reduction temperature range is 300° C., to obtain a mechanical mixture of fully mixed and non-oxidized metal powder;

Step 5, put the metal powder mixture in step 4 into a graphite mold, and sinter it in a spark plasma sintering equipment. Protect.

The density of the W-Cu-Ni alloy prepared by this method is 97.66%, and the degree of W-W connection is 29%.

Claims (6)

1. one kind low W-W connection degree W-Cu-Ni alloy material, it is characterized in that: the composition of W-Cu-Ni alloy is by mass percentage: W content 65%～80%, Cu content 15%～25%, Ni content 5%～10%.

2. material as claimed in claim 1, it is characterized in that: described material prepares by following process:

(1) adopt the method for chemical nickel plating to prepare nickel coating tungsten composite powder, recycling planetary ball mill (without abrading-ball) coats tungsten composite powder and copper powder wet mixing 1～2h by nickel;

(2) alloying element powder mixed in (1) is reduced in hydrogen atmosphere to 0.5～1h, the reduction temperature scope is 200～300 ℃, obtains mixing fully and the mechanical impurity of the metal dust of non-oxidation;

(3) adopt discharge plasma sintering technique to carry out sintering to gained mixed-powder in (2), sintering temperature is 850～950 ℃, exerting pressure is 20～50MPa, temperature retention time is 5～10min, the sintering atmosphere is vacuum, finally obtains having the W-Cu-Ni alloy of high-compactness and low W-W degree of connection.

3. preparation method as claimed in claim 2, it is characterized in that: in chemical plating bath, the six hydration nickel sulfate concentration range is that 20～40g/L, hypophosphorous acid hydrogen na concn scope are that 20～40g/L, ammonium chloride concentration scope are that 30～40g/L, sodium pyrophosphate concentration range are that 50～70g/L, sodium citrate concentration scope are that 5～10g/L, triethanolamine concentration range are 90～120g/L, bath temperature is 35～40 ℃, the pH value is 8～10, and the chemical plating plating time is 20～40min.

4. preparation method as claimed in claim 2, it is characterized in that: selecting Tungsten Powder Size is 4～6 μ m, and copper powder size is 0.5～1 μ m.

5. preparation method as claimed in claim 2, it is characterized in that: chemical deposit is nickel dam, and the nickel coating thickness is 0.1～0.5 μ m, and the nickel clad can reduce W-W connection degree; Utilize between nickel and copper the effect that forms partial miscibility between unlimited solid solution and nickel and tungsten simultaneously, make tungsten phase and copper produce metallurgical binding between mutually, the interface bond strength of raising tungsten phase and Cu phase; Nickel can also improve sintering activity, plays the effect that reduces sintering temperature.

6. preparation method as claimed in claim 2, it is characterized in that: the density of prepared W-Cu-Ni alloy is more than 97.5%, and W-W connection degree is less than 30%.

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