A method for producing a sintered tungsten-copper alloy rod

Abstract

The application provides a preparation method of sintered tungsten-copper alloy rod and relates to the technical field of refractory metal preparation and processing. In the application, two half circular clamps are sleeved outside the cylindrical mold and fastened to prevent the pure tungsten powder blank from being uneven in size and being deformed in bending during pressing. Then, two half circular pure tungsten clamps are sleeved outside the pure tungsten powder blank skeleton and fastened to control the subsequent pre-sintering bending deformation, and the pure tungsten clamps will not contaminate the pure tungsten powder blank. In addition, the temperature of the infiltration sintering is lower than that of the pre-sintering, which can prevent the pre-sintering blank from being deformed in shrinkage again during the infiltration sintering, and finally the sintered tungsten-copper alloy rod which is flat, uniform in size is obtained. The tungsten-copper alloy long rod prepared by the method of the application has a diameter of 30-60mm, a length of 1000-1300mm, an overall bending degree of less than 6mm / m and a density of more than 99%.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of refractory metal preparation and processing, and particularly relates to a preparation method of sintered tungsten-copper alloy rod. BACKGROUND

[0002] Tungsten-copper alloy is a composite material prepared by powder metallurgy process, in which tungsten and copper are neither mutually soluble nor form intermetallic compounds. As a kind of "pseudo-alloy", tungsten-copper alloy has high hardness, high melting point, good electrical conductivity and thermal conductivity, high electric breakdown strength, high welding resistance, high heat resistance and corrosion resistance, and is widely used as electrode material for various high and low voltage vacuum switch electrical appliances, electronic packaging and heat sink materials for high-power devices, shaped charge liner armor materials, high-temperature sweating refrigeration materials in aerospace technology, etc. The preparation methods of tungsten-copper alloy include infiltration method, high-temperature liquid phase sintering method, activated liquid phase sintering method, spark plasma sintering method, hot-pressing sintering method and injection molding sintering technology, etc. The tungsten-copper alloy prepared by the infiltration method has higher density and is widely used in production.

[0003] During the preparation and processing of tungsten-copper alloy by powder metallurgy process, the material density is often low, which requires higher processing technology. If the size of tungsten-copper alloy rod or plate is too large, the sintering difficulty will be increased, the material shrinkage during sintering or the infiltration will not be sufficient, resulting in a large number of pores in the structure, which is difficult to form high densification, and the insufficient density will greatly reduce the physical and mechanical properties of the material. In addition, the powder metallurgy material will shrink to some extent during sintering, and the shrinkage is often uneven, making it difficult to accurately control the size of the product, and the material will be wasted after machining and shaping. With the decrease of the diameter and the increase of the length of tungsten-copper alloy rod products, the tungsten skeleton preparation and infiltration sintering process will cause large bending deformation of the rod, and the overall bending degree of the rod is often more than 25mm / m, which will lead to subsequent machining difficulties or make the product directly scrap. In order to avoid these problems, the size of tungsten-copper alloy rod and plate products will be controlled in actual production, so that the tungsten-copper alloy rod products provided on the market have a diameter of not more than 50mm, a length of not more than 200mm, a length and width size of not more than 200mm, and a thickness of not more than 50mm, and these size products can meet most of the market application requirements.

[0004] With the advancement of electrical discharge machining (EDM) and laser technology towards higher power, the excellent comprehensive properties of tungsten-copper alloys make them a candidate material for high-power EDM electrodes and structural materials for high-power excimer lasers or CO2 lasers. This leads to increased dimensional requirements for tungsten-copper alloy products. For larger tungsten-copper alloy products, the common processing method involves large-scale plastic deformation of sintered blanks. However, the high hardness and melting point of tungsten-copper alloys result in poor plastic deformation, low yield, and high requirements for plastic deformation processing technology and equipment, leading to significant material and equipment costs. For tungsten-copper alloy rods with diameters of 30–60 mm and lengths exceeding 1000 mm, there are currently few manufacturers or technologies capable of producing products of similar dimensions. Furthermore, the dimensions of products prepared using conventional powder metallurgy processes cannot be precisely controlled, and plastic deformation processing of sintered blanks is even more challenging. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing sintered tungsten-copper alloy rods. Using this method, sintered tungsten-copper alloy long rods with a diameter of 30-60 mm, a length of 1000-1300 mm, an overall curvature of less than 6 mm / m, and a density of greater than 99% can be prepared. These sintered long rods can then be directly turned on a lathe or ground with a centerless grinder to remove a small amount of copper residue on the surface to obtain regular long rod products.

[0006] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0007] This invention provides a method for preparing sintered tungsten-copper alloy rods, comprising the following steps:

[0008] Tungsten powder is loaded into a cylindrical mold, and a two-lobed semi-circular clamp is fitted onto the outside of the mold and tightened. Cold isostatic pressing is then performed to obtain a pure tungsten powder blank. The cylindrical mold has shrinkage and rebound properties.

[0009] A two-lobed semi-circular pure tungsten clamp is fitted onto the outside of the pure tungsten powder blank and tightened. The resulting tightened blank is pre-sintered in a hydrogen atmosphere. The pure tungsten clamp is then removed to obtain a pure tungsten pre-sintered blank.

[0010] Pure copper sheets are bound to the outside of the pure tungsten pre-sintered billet, and melt infiltration sintering is carried out in a hydrogen atmosphere to obtain sintered tungsten-copper alloy rods; the melt infiltration sintering temperature is lower than the pre-sintering temperature.

[0011] Preferably, the inner diameter of the two-lobed semi-circular clamp is 0.5-1 mm larger than the outer diameter of the cylindrical mold, the length is 180-220 mm shorter than the cylindrical mold, and the thickness is 1.5-3 mm.

[0012] Preferably, the material of the cylindrical mold is silica gel; and the two-part half-round clamp is a steel clamp.

[0013] Preferably, the pressure of the cold isostatic pressing is 160-200 MPa, and the pressure holding time is 3-10 minutes.

[0014] Preferably, the inner diameter of the two-part half-round pure tungsten clamp is 3-5 mm larger than the diameter of the pure tungsten powder blank, the length is 20-40 mm longer than the length of the pure tungsten powder blank, and the thickness is 2.5-4 mm.

[0015] Preferably, the temperature of the pre-sintering is 1400℃±20℃, and the holding time is 2-3 hours.

[0016] Preferably, the width of the pure copper sheet is not greater than 1 / 2 of the diameter of the pure tungsten pre-sintering blank, the length is not greater than the length of the pure tungsten pre-sintering blank, and the thickness is 1-5 mm. The weight of the pure copper sheet is n times the weight of the pure tungsten pre-sintering blank, the mass fraction of copper in the target sintered tungsten-copper alloy rod is ω, and the required weight of the pure copper sheet satisfies the relationship of formula 1: n / (1+n)=ω+(0.8%-1.2%) formula 1.

[0017] Preferably, the mass fraction of copper in the sintered tungsten-copper alloy rod is 25-30%.

[0018] Preferably, the temperature of the infiltration sintering is 1300℃±20℃, and the holding time is 1-1.5 hours.

[0019] Preferably, the diameter of the sintered tungsten-copper alloy rod is 30-60 mm, and the length is 1000-1300 mm.

[0020] The application provides a preparation method of a sintered tungsten-copper alloy rod, which comprises the following steps: loading tungsten powder into a cylindrical mold, sleeving a two-part half-round clamp outside the mold and fastening, performing cold isostatic pressing, and obtaining a pure tungsten powder blank; the cylindrical mold has a shrinkage and recovery performance; sleeving a two-part half-round pure tungsten clamp outside the pure tungsten powder blank and fastening, pre-sintering the obtained fastened blank in a hydrogen atmosphere, removing the pure tungsten clamp, and obtaining a pure tungsten pre-sintering blank; binding a pure copper sheet outside the pure tungsten pre-sintering blank, performing infiltration sintering in a hydrogen atmosphere, and obtaining a sintered tungsten-copper alloy rod; and the temperature of the infiltration sintering is lower than that of the pre-sintering.

[0021] The two-piece half-circle clamp is sleeved outside the cylindrical mold and fastened to prevent uneven size and bending deformation of the pure tungsten powder blank during pressing, and then cold isostatic pressing is performed to obtain a relatively flat and uniform size pure tungsten powder blank skeleton. Then, the two-piece half-circle pure tungsten clamp is sleeved outside the pure tungsten powder blank skeleton and fastened to control the subsequent pre-sintering bending deformation, and the pure tungsten clamp will not contaminate the pure tungsten powder blank. In addition, the temperature of the infiltration sintering is lower than that of the pre-sintering, which can prevent the pre-sintering blank from shrinking and deforming again during infiltration sintering, and finally obtain a flat and uniform size sintered tungsten-copper alloy rod.

[0022] The results of the embodiment show that the sintered tungsten-copper alloy long rod with a diameter of 30-60mm, a length of 1000-1300mm, an overall bending degree of less than 6mm / m and a density of more than 99% can be prepared by the method of the present application. After the sintered long rod is ground by a lathe or a centerless grinding machine, a regular long rod product can be obtained. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 It is a schematic diagram of the two-piece half-circle steel clamp and the pure tungsten clamp;

[0024] Figure 2 It is a physical diagram of the pure tungsten powder blank, the pre-sintering blank and the rod product prepared in Comparative Example 1;

[0025] Figure 3 It is a physical diagram of the pure tungsten powder blank, the pre-sintering blank and the rod product prepared in Comparative Example 2;

[0026] Figure 4 It is a physical diagram of the pure tungsten powder blank, the pre-sintering blank and the rod product prepared in Example 1. DETAILED DESCRIPTION

[0027] The present application provides a preparation method of a sintered tungsten-copper alloy rod, which comprises the following steps:

[0028] The tungsten powder is loaded into a cylindrical mold, a two-piece half-circle clamp is sleeved outside the mold and fastened, and cold isostatic pressing is performed to obtain a pure tungsten powder blank; the cylindrical mold has a shrinkage and recovery performance;

[0029] A two-piece half-circle pure tungsten clamp is sleeved outside the pure tungsten powder blank and fastened, and the obtained fastened blank is pre-sintered in a hydrogen atmosphere, the pure tungsten clamp is removed, and a pure tungsten pre-sintering blank is obtained;

[0030] Pure copper sheets are bound outside the pure tungsten pre-sintering blank, and infiltration sintering is performed in a hydrogen atmosphere to obtain a sintered tungsten-copper alloy rod; the temperature of the infiltration sintering is lower than that of the pre-sintering.

[0031] The application packs tungsten powder into a cylindrical mold, adopts two-piece half-round clamps to be sleeved outside the mold and fastened, and then cold isostatic pressing is carried out to obtain pure tungsten powder blank.

[0032] In the application, the purity of the tungsten powder is preferably not less than 99.7%; the Fisher particle size of the tungsten powder is preferably 7-10 μm; and before being packed into the cylindrical mold, the tungsten powder is preferably first screened by using an electric rotary vibration screen equipped with a 2400-mesh screen, and the tungsten powder on the screen is taken. In the application, the rotary vibration frequency of the electric rotary vibration screen is preferably 200 times per minute, and the time is preferably 3-5 minutes. In the application, the electric rotary vibration screen equipped with a 2400-mesh screen screens off most satellite powder particles less than 5 μm, reduces the probability of closed pores formed by the blocking of satellite powder in tungsten skeleton pores, and improves the sintering density of the material in the later stage.

[0033] In the application, the cylindrical mold has shrinkage and resilience performance, and the material of the cylindrical mold is preferably silica gel; and the two-piece half-round clamps are preferably steel clamps. In the application, the steel clamps do not deform and crack under the cold isostatic pressing of 200 MPa, and the cost is low. In the application, the structure diagram of the two-piece half-round clamps is shown in Figure 1

[0034] In the application, the inner diameter of the two-piece half-round clamps is preferably 0.5-1 mm larger than the outer diameter of the cylindrical mold, and more preferably 0.6-0.8 mm larger; the length is preferably 180-220 mm shorter than the cylindrical mold, and more preferably 190-210 mm shorter; and the thickness is preferably 1.5-3 mm, and more preferably 2-2.5 mm. In the cold isostatic pressing process, the powder blank will shrink obviously under pressure, and the powder will be extruded with the shrinkage of the two ends of the cylindrical mold. In the application, the length of the two-piece half-round clamps is controlled to be 180-220 mm shorter than the cylindrical mold, which can avoid the friction or scratching of the two ends of the cylindrical mold in contact with the steel mold, and damage the cylindrical mold and the sealing performance of the seal.

[0035] In the application, the tungsten powder is packed into the cylindrical mold, the mold port is plugged with a rubber plug, and then the two-piece half-round clamps are sleeved outside the silica gel mold and fastened, and then cold isostatic pressing is carried out.

[0036] In the application, the pressure of the cold isostatic pressing is preferably 160-200 MPa, and more preferably 170-190 MPa; and the pressure holding time is preferably 3-10 minutes, and more preferably 5-7 minutes.

[0037] In the application, the two-piece half-round clamps are sleeved outside the cylindrical mold and fastened to prevent the pure tungsten powder blank from being uneven in size and deformed in bending during pressing, and to obtain a relatively flat and uniform pure tungsten powder blank.

[0038] ​After obtaining the pure tungsten powder blank, the two-lobed semi-circular pure tungsten clamp is sleeved outside the pure tungsten powder blank and fastened, the obtained fastened blank is pre-sintered in a hydrogen atmosphere, the pure tungsten clamp is taken out, and a pure tungsten pre-sintered blank is obtained.

[0039] In the present application, the inner diameter of the two-lobed semi-circular pure tungsten clamp is preferably 3-5 mm larger than the diameter of the pure tungsten powder blank, more preferably 3.5-4.5 mm larger; the length is preferably 20-40 mm longer than the length of the pure tungsten powder blank, more preferably 25-35 mm longer; and the thickness is preferably 2.5-4 mm, more preferably 3-3.5 mm.

[0040] In the present application, the two-lobed semi-circular pure tungsten clamp is sleeved outside the pure tungsten powder blank and fastened, which can prevent pre-sintering from being bent and deformed, and the pure tungsten clamp will not contaminate the pure tungsten powder blank.

[0041] In the present application, the pre-sintering temperature is preferably 1400℃±20℃, more preferably 1400±10℃; and the holding time is preferably 2-3 hours. In the pre-sintering process, the hydrogen gas is used to reduce the oxide layer and further reduce the oxygen in the raw material tungsten powder, thereby activating the material and facilitating the subsequent copper-tungsten interface bonding and densification.

[0042] After the pre-sintering is completed, the pure tungsten clamp is then preferably opened and the pure tungsten pre-sintered blank is taken out.

[0043] After obtaining the pure tungsten pre-sintered blank, a pure copper sheet is bound outside the pure tungsten pre-sintered blank, and the infiltrated sintering is carried out in a hydrogen atmosphere to obtain a sintered tungsten-copper alloy rod; and the temperature of the infiltrated sintering is lower than that of the pre-sintering.

[0044] In the present application, the width of the pure copper sheet is preferably not greater than 1 / 2 of the diameter of the pure tungsten pre-sintered blank, the length is preferably not greater than the length of the pure tungsten pre-sintered blank, and the thickness is preferably 1-5 mm, more preferably 2-4 mm; the weight of the pure copper sheet is n times the weight of the pure tungsten pre-sintered blank, the mass fraction of copper in the target sintered tungsten-copper alloy rod is ω, and the required weight of the pure copper sheet satisfies the relationship of formula 1: n / (1+n)=ω+(0.8%~1.2%) formula 1. In the present application, the mass fraction of copper in the sintered tungsten-copper alloy rod is preferably 25-30%.

[0045] In the present application, the temperature of the infiltrated sintering is preferably 1300℃±20℃, more preferably 1300±10℃; and the holding time is preferably 1-1.5 hours. The infiltrated sintering is preferably carried out in an alumina ceramic boat. By controlling the temperature of the infiltrated sintering to be lower than that of the pre-sintering, the present application can prevent the pre-sintered blank from being deformed again during the infiltrated sintering, and finally obtain a sintered tungsten-copper alloy rod that is flat and uniform in size.

[0046] In the present application, after the infiltration sintering, the present application is preferably cooled to room temperature with the furnace.

[0047] The preparation method of the sintered tungsten-copper alloy rod provided by the present application will be described in detail below in combination with examples, but they should not be understood as limiting the scope of protection of the present application.

[0048] Example 1

[0049] (1) The tungsten powder with a purity of 99.7% and a Fisher particle size of 7-10 μm was sieved in an electric rotary vibration sieve equipped with a 2400-mesh screen for 3 minutes at a rotary vibration frequency of 200 times per minute to obtain the sieved tungsten powder.

[0050] (2) The sieved tungsten powder was loaded into a cylindrical silica gel mold with an outer diameter of Φ 40 (an inner diameter of Φ 34) mm x 1300 mm, the mold port was tightly plugged with a rubber plug, a two-limb half-circular steel clamp with an outer diameter of Φ 44 (an inner diameter of Φ 41) mm x 1100 mm was sleeved outside the silica gel mold and fastened (as shown in Figure 1 ), and then cold isostatic pressing was performed at a pressure of 200 MPa for 10 minutes to obtain a relatively flat Φ 30.5 mm x 1030 mm pure tungsten powder blank.

[0051] (3) A two-limb half-circular pure tungsten clamp with an outer diameter of Φ 40 (an inner diameter of Φ 34) mm x 1100 mm was sleeved outside the pure tungsten powder blank and fastened, and then pre-sintering was performed in a hydrogen high-temperature furnace, the pre-sintering temperature was 1400°C, the holding time was 2 hours, then the furnace was cooled to room temperature, the pure tungsten clamp was opened, and a pure tungsten pre-sintering blank with a size of about Φ 30 mm x 1000 mm was taken out.

[0052] (4) The rod-shaped pre-sintering blank was side-bundled with pure copper sheets with a weight of about 35% of the blank, placed in an alumina ceramic boat in a hydrogen high-temperature furnace for infiltration sintering, the sintering temperature was 1300°C, the holding time was 1 hour, then the furnace was cooled to room temperature, and a flat W75Cu25 alloy rod with a size of Φ 30 mm x 1000 mm was obtained.

[0053] Example 2

[0054] (1) The tungsten powder with a purity of 99.7% and a Fisher particle size of 7-10 μm was sieved in an electric rotary vibration sieve equipped with a 2400-mesh screen for 3 minutes at a rotary vibration frequency of 200 times per minute to obtain the sieved tungsten powder.

[0055] (2) The oversize tungsten powder is loaded into a cylindrical silica gel mold with an outer diameter of Φ51 (inner diameter Φ45) mm x 1500 mm, the mold port is plugged with a rubber plug, a two-lobed half-circle steel clamp with an outer diameter of Φ56 (inner diameter Φ52) mm x 1300 mm is sleeved outside the silica gel mold and fastened, and then cold isostatic pressing is carried out with a pressure of 200 MPa and a pressure maintaining time of 3 minutes, to obtain a relatively flat Φ40.8 mm x 1240 mm pure tungsten powder blank.

[0056] (3) A two-lobed half-circle pure tungsten clamp with an outer diameter of Φ50 (inner diameter Φ44) mm x 1300 mm is sleeved outside the pure tungsten powder blank and fastened, and then pre-sintering is carried out in a hydrogen high-temperature furnace, with a pre-sintering temperature of 1400℃ and a holding time of 2 hours, and then the furnace is cooled to room temperature, the pure tungsten clamp is opened, and a pure tungsten pre-sintered blank with a size of about Φ40 mm x 1300 mm is taken out.

[0057] (4) The rod-shaped pre-sintered blank is bound with pure copper sheets with a weight of about 45% of the blank weight on the side, placed in an alumina ceramic boat in a hydrogen high-temperature furnace for infiltration sintering, with a sintering temperature of 1300℃ and a holding time of 1 hour, and then the furnace is cooled to room temperature, to obtain a flat W70Cu30 alloy rod with a size of Φ40 mm x 1300 mm.

[0058] Example 3

[0059] (1) Tungsten powder with a purity of 99.7% and Fisher particle size of 7-10 μm is sieved in an electric rotary vibration sieve equipped with a 2400-mesh screen for 3 minutes at a rotary vibration frequency of 200 times / minute, to obtain oversize tungsten powder.

[0060] (2) The oversize tungsten powder is loaded into a cylindrical silica gel mold with an outer diameter of Φ62 (inner diameter Φ56) mm x 1300 mm, the mold port is plugged with a rubber plug, a two-lobed half-circle steel clamp with an outer diameter of Φ68 (inner diameter Φ63) mm x 1100 mm is sleeved outside the silica gel mold and fastened, and then cold isostatic pressing is carried out with a pressure of 200 MPa and a pressure maintaining time of 10 minutes, to obtain a relatively flat Φ50.7 mm x 1030 mm pure tungsten powder blank.

[0061] (3) A two-lobed half-circle pure tungsten clamp with an outer diameter of Φ62 (inner diameter Φ55) mm x 1100 mm is sleeved outside the pure tungsten powder blank and fastened, and then pre-sintering is carried out in a hydrogen high-temperature furnace, with a pre-sintering temperature of 1400℃ and a holding time of 2 hours, and then the furnace is cooled to room temperature, the pure tungsten clamp is opened, and a pure tungsten pre-sintered blank with a size of about Φ50 mm x 1000 mm is taken out.

[0062] (4) The rod-like pre-sintered blank is side-bundled with pure copper sheets of about 35% of the blank weight, and is placed in an alumina ceramic boat for infiltration sintering in a hydrogen high-temperature furnace. The sintering temperature is 1300°C, and the holding time is 1 hour. Then the furnace is cooled to room temperature, and a Φ50mm x 1000mm flat W75Cu25 alloy rod is obtained.

[0063] Example 4

[0064] (1) The tungsten powder with a purity of 99.7% and a Fisher particle size of 7-10 μm is sieved in an electric rotary vibration sieve equipped with a 2400-mesh screen for 5 minutes at a rotary vibration frequency of 200 times per minute to obtain the sieved tungsten powder.

[0065] (2) The sieved tungsten powder is loaded into a Φ74 (Φ68) mm x 1500mm cylindrical silica gel mold, the mold port is tightly plugged with a rubber plug, a Φ81 (Φ75) mm x 1300mm two-leaf half-circle steel clamp is sleeved outside the silica gel mold and fastened, and then cold isostatic pressing is performed at a pressure of 200 MPa for 3 minutes to obtain a relatively flat Φ61 mm x 1240mm pure tungsten powder blank.

[0066] (3) A Φ74 (Φ66) mm x 1300mm two-leaf half-circle pure tungsten clamp is sleeved outside the pure tungsten powder blank framework and fastened, and then pre-sintering is performed in a hydrogen high-temperature furnace. The pre-sintering temperature is 1400°C, and the holding time is 2 hours. Then the furnace is cooled to room temperature, the pure tungsten clamp is opened, and a Φ60 mm x 1300mm pure tungsten pre-sintered blank is obtained.

[0067] (4) The rod-like pre-sintered blank is side-bundled with pure copper sheets of about 45% of the blank weight, and is placed in an alumina ceramic boat for infiltration sintering in a hydrogen high-temperature furnace. The sintering temperature is 1300°C, and the holding time is 1 hour. Then the furnace is cooled to room temperature, and a Φ60 mm x 1300mm flat W70Cu30 alloy rod is obtained.

[0068] Comparative Example 1

[0069] The difference from Example 1 is that steps (2) and (3) do not use a clamp.

[0070] Comparative Example 2

[0071] The difference from Example 1 is that the pre-sintering temperature is changed to 1300°C, and the infiltration temperature is changed to 1400°C to prepare a W75Cu25 alloy rod.

[0072] Comparative Examples 3 and 4 Figures 2 to 4The different methods are prepared for effect comparison chart, wherein, on the basis of the preparation method of example 1, the steel clamp and the pure tungsten clamp are not used to prepare the rod product, Figure 2 The state chart prepared by the method (comparative example 1) is shown in Fig. 1. Figure 2 It is found that the powder billet long rod obtained has a certain bending, the bending degree is >10mm / m, the free shrinkage of the powder billet during pre-sintering causes the bending to be intensified, the bending degree of the pre-sintered billet obtained is >30mm / m, the bending degree of the pre-sintered billet during the high-temperature infiltration process is not intensified, and the final determination of the bending degree of the long rod product prepared reaches 33mm / m. On the basis of the preparation method of example 1, the pre-sintering temperature is changed to 1300℃, and the infiltration temperature is changed to 1400℃ by using the conventional sintering system to prepare the rod product, Figure 3 The state chart prepared by the method (comparative example 2) is shown in Fig. 2. Figure 3 It is found that the powder billet and the pre-sintered billet keep good flatness under the action of the steel clamp and the pure tungsten clamp, and the bending degree is less than 6mm / m. The pre-sintered billet occurs free shrinkage during the infiltration due to the temperature rise, and the bending degree reaches 28mm / m. Figure 4 The state chart of the tungsten-copper long rod prepared by example 1 of the present application is shown in Fig. 3. Figure 4 It can be seen that the powder billet, the pre-sintered billet and the long rod product after the infiltration all have good flatness, and the bending degree is less than 6mm / m due to the use of the steel clamp, the pure tungsten clamp and the improved sintering temperature process.

[0073] Table 1 is a performance comparison table of the W75Cu25 alloy rod prepared by different methods.

[0074] Table 1 is the bending degree and density of the alloy rod product of the example and the comparative example.

[0075] Method of manufacture Comparative Example 1 Comparative Example 2 Example 1 Example 2 Example 3 Example 4 Finished product flexibility 33 mm / m 28 mm / m 4 mm / m 3 mm / m 3 mm / m 3 mm / m Finished product density 99.3％ 99.2％ 99.3％ 99.1％ 99.2％ 99.1％

[0076] It can be seen from table 1 that the tungsten-copper alloy long rod prepared by different preparation methods and each example method all has good density, and is higher than 99%. It can be seen that compared with the conventional method without using the clamp and the conventional sintering temperature method, the tungsten-copper alloy long rod prepared by the method of the present application has a significant advantage in flatness, and also maintains a very high density.

[0077] The above only describes the preferred embodiments of the present application, and it should be pointed out that for ordinary skilled in the art, without departing from the principles of the present application, a number of improvements and refinements can be made, and these improvements and refinements should also be considered as the protection scope of the present application.

Claims

1. A method of producing a sintered tungsten-copper alloy rod, characterized by, The method comprises the following steps: The tungsten powder is loaded into a cylindrical mold, a two-piece half-circle tungsten clamp is sleeved outside the mold and fastened, cold isostatic pressing is performed to obtain a pure tungsten powder blank; the cylindrical mold has a shrinkage and springback performance; The two-piece half-circle tungsten clamp is sleeved outside the pure tungsten powder blank and fastened, the obtained fastened blank is pre-sintered in a hydrogen atmosphere, the pure tungsten clamp is taken out, and a pure tungsten pre-sintered blank is obtained; A pure copper sheet is bound outside the pure tungsten pre-sintered blank, and infiltration sintering is performed in a hydrogen atmosphere to obtain a sintered tungsten-copper alloy rod; the temperature of the infiltration sintering is lower than that of the pre-sintering; the temperature of the pre-sintering is 1400℃±20℃; the temperature of the infiltration sintering is 1300℃±20℃; The inner diameter of the two-piece half-circle clamp is 0.5-1mm larger than the outer diameter of the cylindrical mold, the length is 180-220mm shorter than the cylindrical mold, and the thickness is 1.5-3mm; The diameter of the sintered tungsten-copper alloy rod is 30-60mm, and the length is 1000-1300mm.

2. The production method according to claim 1, characterized by, The material of the cylindrical mold is silica gel, and the two-piece half-circle clamp is a steel clamp.

3. The production method according to claim 1 or 2, characterized by, The pressure of the cold isostatic pressing is 160-200MPa, and the pressure holding time is 3-10 minutes.

4. The method of claim 1, wherein, The inner diameter of the two-piece half-circle tungsten clamp is 3-5mm larger than the diameter of the pure tungsten powder blank, the length is 20-40mm longer than the pure tungsten powder blank, and the thickness is 2.5-4mm.

5. The production method according to claim 1 or 4, characterized by, The holding time of the pre-sintering is 2-3 hours.

6. The method of claim 1, wherein, The width of the pure copper sheet is not greater than 1 / 2 of the diameter of the pure tungsten pre-sintered blank, the length is not greater than the length of the pure tungsten pre-sintered blank, the thickness is 1-5mm, the weight of the pure copper sheet is n times the weight of the pure tungsten pre-sintered blank, the mass fraction of copper in the target sintered tungsten-copper alloy rod is ω, and the required weight of the pure copper sheet satisfies the relationship of formula 1: n / (1+n)=ω+(0.8%-1.2%) Formula 1.

7. The production method according to claim 6, characterized by, The mass fraction of copper in the sintered tungsten-copper alloy rod is 25-30%.

8. The production method according to claim 1 or 6, characterized by, The holding time of the infiltration sintering is 1-1.5 hours.

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