Method for preparing tantalum wire with improved brittleness resistance and tantalum wire prepared by method

Abstract

The invention provides a method for preparing a tantalum wire with improved brittleness resistance, and the method sequentially comprises the following steps: (1) mixing tantalum powder and dopant powder to form a first mixture, and the dopant powder is rare earth element powder, germanium powder or silicon powder; (2) performing cold isostatic pressing on the first mixture to obtain a master alloy blank; (3) carrying out vertical fusion sintering on the mother alloy blank; (4) carrying out hydrogenation and powder preparation on the mother alloy blank subjected to vertical fusion sintering to obtain mother alloy tantalum powder; (5) mixing the tantalum powder and one or more mother alloy tantalum powder to form a second mixture; and (6) preparing the tantalum wire by adopting the second mixture as a powder raw material. The invention also relates to the tantalum wire with improved brittleness resistance prepared by the method.

Description

Technical Field

[0001] The present invention relates to the technical field of tantalum or tantalum alloy processing, and in particular to a method for preparing a tantalum wire with improved brittleness resistance and the tantalum wire prepared by the method. Background Art

[0002] The tantalum wire of the anode lead of conventional capacitors is not doped. However, due to the current technical requirements of capacitors, the sintering temperature of the anode block is significantly increased, so the grain size of the lead tantalum wire on the anode block will be significantly increased, so that the harmful impurities in the tantalum powder of the anode block will easily diffuse into the tantalum wire, causing the tantalum wire to become brittle. For tantalum wire, brittle resistance refers to pressing capacitor-grade tantalum powder and tantalum wire into an anode block according to a molding process, and the depth of the tantalum wire buried in the anode block is about 1 / 3 of the anode block; the formed anode block is sintered at 1500-1900℃, and then the tantalum wire exposed outside the anode block is subjected to a bending test until it breaks. The number of bends indicates the brittle resistance of the tantalum wire.

[0003] Therefore, in order to solve this problem, a certain amount of rare earth elements are added to the tantalum wire. These rare earth elements will be distributed on the grain boundaries (which is beneficial to the purpose of refining the grains of the tantalum wire) and will inhibit the growth of the grains of the high-temperature tantalum wire. This method is called doping. The traditional tantalum wire doping method is to directly add rare earth metals to tantalum powder, and then make metal billets for tantalum wire through mixing, molding, isostatic pressing, and vertical melting sintering. The billets are then rolled and drawn to make capacitor-grade tantalum wire.

[0004] Cao Hansong studied the effect of doping on the individual properties of tantalum wire in his paper "Process Methods for Improving the Performance of Tantalum Wire" published in Volume 30, Issue 2 of Rare Metals and Cemented Carbides (June 2002). The results show that no matter whether trace element A or trace element B is doped, as long as the doping amount is appropriate and the distribution is uniform, the brittleness resistance of tantalum wire can be improved, that is, the brittleness resistance of doped tantalum wire is much better than that of pure tantalum wire, especially the brittleness resistance of tantalum wire doped with both A and B is more prominent. Adding both A and B to tantalum wire can inhibit grain growth and refine the grains. This is the solid-state doping method of pure rare earth elements: pure rare earth elements are added to tantalum powder in a certain proportion, and then isostatically pressed and vertically melt-sintered to form a product with high brittleness resistance. The disadvantage of this method is that due to the large difference in the loose specific gravity between tantalum powder and the single element, the single rare earth element will float on the tantalum powder during the mixing process after the addition, and the materials cannot be completely mixed. The tantalum wire produced often has problems such as uneven doping distribution, uneven grains, fluctuations in tensile strength, and poor consistency in brittleness resistance.

[0005] In addition, Chinese patent CN 111910097 B discloses a method for preparing silicon-doped tantalum wire. Different from the traditional solid-state mixing and silicon-doping, this invention advances the silicon-doping step to the crystallization step of preparing potassium fluorotantalate. Silicon is easily soluble in hydrofluoric acid, while potassium fluorosilicate has a low solubility in the system. Liquid silicon is used to achieve uniform silicon incorporation into potassium fluorotantalate. When using potassium fluorotantalate to produce tantalum wire, silicon will not be lost in subsequent processes such as reduction and vertical melting, and will eventually enter the tantalum wire evenly. Using this inventive method, uniform silicon incorporation can be achieved, improving the performance of silicon-doped tantalum wire products. This is the reduction tantalum powder crystallization method of potassium fluorotantalate doping. However, the tantalum powder produced by this method contains a large amount of fluoride salt, which has a great impact on the performance of the tantalum powder. Therefore, after the tantalum powder is produced, it needs to be pickled and washed with water. Since the F- ions in the fluoride salt encounter the hydrogen ions in the hydrochloric acid, hydrofluoric acid will be formed. This hydrofluoric acid has a certain solubility in the silicon element, so the silicon content in the tantalum powder will be greatly reduced. Therefore, it is difficult to stably incorporate uniform silicon using this method.

[0006] Therefore, a method for preparing tantalum wire with improved brittleness resistance is needed. The tantalum wire prepared by this method has high brittleness resistance and can effectively improve the uniformity of the grains of the tantalum billet, while improving the tensile strength, elongation and other properties of the tantalum wire, thereby solving the problem of poor brittleness resistance of the tantalum wire during the capacitor sintering process. Summary of the invention

[0007] One technical problem to be solved by the present invention is the brittleness of the tantalum wire anode block lead. Furthermore, another technical problem to be solved by the present invention is the inconsistency of the brittleness resistance, strength, bending and other properties caused by the uneven distribution of grains inside the tantalum wire after doping by the traditional method.

[0008] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0009] A method for preparing tantalum wire with improved brittleness resistance, the method comprising the following steps in sequence: (1) mixing tantalum powder and dopant powder to form a first mixture, wherein the dopant powder is rare earth element powder, germanium powder or silicon powder; (2) cold isostatic pressing the first mixture to obtain a master alloy billet; (3) performing vertical melt sintering on the master alloy billet; (4) hydrogenating and pulverizing the master alloy billet after vertical melt sintering to obtain a master alloy tantalum powder; (5) mixing tantalum powder and one or more master alloy tantalum powders to form a second mixture; and (6) using the second mixture as a raw material to prepare tantalum wire.

[0010] Preferably, in step (1), the tantalum powder and the dopant powder are mixed in a mass ratio of 99:1-98.5:1.5.

[0011] Preferably, in step (2), the cold isostatic pressing is performed at a pressure of 150-210 MPa.

[0012] Preferably, in step (3), the vertical melting sintering is carried out by keeping the temperature at a high temperature holding point, and the high temperature holding point is 67-84% of the melting point of tantalum. The melting point of tantalum is 2996° C. It should be noted that those skilled in the art can reasonably determine the holding time according to the set high temperature holding point temperature. As a non-limiting example, the holding time is 1-3 hours.

[0013] Preferably, the hydrogenation in step (4) is carried out in the following manner: the mother alloy billet after vertical melting and sintering is loaded into a hydrogenation furnace, the furnace temperature is set to 800-950° C., hydrogen is introduced, and the temperature is kept. It should be noted that those skilled in the art can reasonably determine the holding time according to the set furnace temperature. As a non-limiting example, the holding time is 1-3 hours.

[0014] Preferably, the powder making in step (4) comprises the following steps: taking out the hydrogenated master alloy billet from the hydrogenation furnace, crushing it in a crusher, and obtaining the master alloy tantalum powder by screening.

[0015] Preferably, the master alloy tantalum powder is a master alloy tantalum powder with a sieve size below 200 mesh.

[0016] Preferably, after step (4) and before step (5), the following steps are also included: loading the master alloy tantalum powder into a deoxidation furnace, loading magnesium powder, and keeping warm (technical personnel in this field can reasonably determine the insulation time according to the deoxidation requirements. As a non-limiting example, the insulation time is 1-3 hours); acid-washing the deoxidized master alloy tantalum powder, and then rinsing it in pure water; and drying the rinsed master alloy tantalum powder in an oven.

[0017] Preferably, in step (5), the tantalum powder and one or more master alloy tantalum powders are mixed so that the mass content of the rare earth element or silicon in the second mixture does not exceed 500 ppm, preferably does not exceed 400 ppm.

[0018] Preferably, the rare earth element is yttrium or cerium.

[0019] Preferably, the tantalum powder in step (1) is metallurgical grade tantalum powder, and the bulk density of the tantalum powder is 3.0-4.0 g / cm 3 The average particle size is between 5.0 and 7.5 microns.

[0020] Preferably, the tantalum powder in step (5) is metallurgical grade tantalum powder, and the bulk density of the tantalum powder is 3.0-4.0 g / cm 3 The average particle size is between 5.0 and 7.5 microns.

[0021] Preferably, the mixing in step (5) is performed for 30-60 minutes.

[0022] It should be noted that the process of preparing tantalum wire from tantalum powder belongs to the conventional technical means in this field. In other words, those skilled in the art know how to carry out step (6) of the above method of using the second mixture as the powder raw material to prepare tantalum wire. Nevertheless, in a preferred embodiment, step (6) includes the following sub-steps: (6-1) cold isostatic pressing the second mixture to obtain a tantalum billet; (6-2) vertical melting sintering the tantalum billet; and (6-3) rolling and drawing the vertical melting sintered tantalum billet.

[0023] As an example, cold isostatic pressing is performed at a pressure of 150-210 MPa in step (6-1).

[0024] As an example, in step (6-2), the tantalum blank is placed in a vacuum induction pre-sintering furnace for sintering, the set temperature is about 1400-2000°C, and the vacuum degree is maintained at 10 -2 Pa or more, and keep warm for a period of time (those skilled in the art can reasonably determine the holding time according to the sintering temperature. As a non-limiting example, the holding time is 1-3 hours); then the tantalum blank is loaded into a vacuum vertical melting sintering furnace, the set temperature is about 2100-2600 ° C, and the vacuum degree is maintained at 10 -3 Pa and keep warm for 0.5-2 hours.

[0025] As an example, in step (6-3), a plurality of rolling passes are performed to obtain a tantalum bar, and the rolling pass processing rate is 10-20%.

[0026] As an example, in step (6-3), the obtained tantalum strip is pickled, dried and placed in a vacuum induction annealing furnace with a set temperature of about 1200-1450°C and a vacuum degree of 10 -3 Pa and keep warm for 0.5-2 hours.

[0027] As an example, in step (6-3), the annealed tantalum strip is subjected to high-temperature gas phase oxidation, the temperature is set to 750-890° C., oxygen is introduced, and the temperature is maintained for 1.5-3 minutes.

[0028] As an example, in step (6-3), the oxidized tantalum bar is drawn in a continuous wire drawing machine, and the final tantalum wire product is drawn according to different specifications required by users.

[0029] Furthermore, the present invention also provides a tantalum wire having improved brittleness resistance, which is prepared by the aforementioned method.

[0030] Compared with the prior art, the method of the present invention is different in that firstly, an alloy powder of tantalum and rare earth elements, germanium or silicon is prepared, which is called master alloy tantalum powder; the combination of rare earth elements, germanium or silicon and tantalum in the master alloy tantalum powder exists in the form of an alloy, and its bulk specific gravity is basically the same as that of tantalum powder. Therefore, when the master alloy tantalum powder is mixed with tantalum powder, there is no stratification problem, and the uniformity of doping is guaranteed. Through this process design, doped tantalum wire with uniform performance and excellent anti-brittleness performance is obtained. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is a typical grain size photograph of the tantalum wire prepared from a mixture of master alloy tantalum powder and tantalum powder in Example 1-70 under 1700°C / 60 minute annealing conditions; the grain size photograph shows that the tantalum wire produced by this method has fine and uniform grains.

[0032] Figure 2 This is a typical grain size photo of the tantalum wire prepared from a direct mixture of yttrium powder and / or silicon powder and tantalum powder in Comparative Examples 2-4 under 1700°C / 60 minutes annealing conditions. The grain size photo shows that the tantalum wire prepared by this method has coarse and uneven grains. DETAILED DESCRIPTION

[0033] In order to further understand the present invention, the preferred embodiments of the present invention are described below in conjunction with examples, but it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention and do not constitute a limitation on the protection scope of the present invention. In other words, the protection scope of the present invention constructed by the claims and their equivalents is not limited to these examples.

[0034] An embodiment of the present invention provides a method for preparing a tantalum wire with improved brittleness resistance, the method comprising the following steps in sequence:

[0035] (1) Tantalum powder and rare earth element (e.g., yttrium, cerium, lanthanum, praseodymium or neodymium) powder, germanium powder or silicon powder are mixed in a mass ratio of 99:1-98.5:1.5 to form a first mixture, wherein the tantalum powder is metallurgical grade tantalum powder, and the bulk density of the tantalum powder is 3.0-4.0 g / cm 3 Between, the average particle size is 5.0-7.5 microns;

[0036] (2) performing cold isostatic pressing on the first mixture at a pressure of 150-210 MPa to obtain a master alloy billet;

[0037] (3) performing vertical melting sintering on the master alloy billet by holding at a high temperature holding point for 1-3 hours and then furnace cooling, wherein the high temperature holding point is 67-84% of the melting point of tantalum, and the melting point of tantalum is 2996° C.;

[0038] (4) The master alloy blank after vertical melting and sintering is loaded into a hydrogenation furnace, the furnace temperature is set to 800-950°C, hydrogen is introduced, and the furnace is cooled after being kept at this temperature for 1-3 hours;

[0039] (5) taking the hydrogenated master alloy billet out of the hydrogenation furnace, crushing it in a crusher, and sieving it to obtain master alloy tantalum powder below 200 mesh;

[0040] (6) Put the master alloy tantalum powder into the oxygen reduction furnace, add magnesium powder, keep it warm for 1-3 hours and cool it;

[0041] (7) acid-washing the deoxidized master alloy tantalum powder, and then rinsing it in pure water;

[0042] (8) drying the rinsed master alloy tantalum powder in an oven to obtain a final master alloy tantalum powder;

[0043] (9) mixing the tantalum powder and the master alloy tantalum powder for 30-60 minutes to form a second mixture, so that the mass content of the rare earth element, germanium or silicon in the second mixture does not exceed 500 ppm, wherein the tantalum powder is metallurgical grade tantalum powder, and the bulk density of the tantalum powder is 3.0-4.0 g / cm 3 The average particle size is between 5.0 and 7.5 microns.

[0044] (10) cold isostatically pressing the second mixture at a pressure of 150-210 MPa to obtain a tantalum billet;

[0045] (11) The tantalum blank is subjected to vertical melting sintering, wherein the tantalum blank is placed in a vacuum induction pre-sintering furnace for sintering, the set temperature is about 1400-2000° C., and the vacuum degree is maintained at 10 -2 Pa, keep warm for 0.5-2 hours and then cool the furnace; then put the tantalum blank into the vacuum vertical melting sintering furnace, set the temperature to about 2100-2600℃, and keep the vacuum degree at 10 -3 Pa, keep warm for 0.5-2 hours and then cool in the furnace;

[0046] (12) performing multiple rolling on the tantalum blank after vertical melting and sintering to obtain tantalum bars, and the rolling pass processing rate is 10-20%;

[0047] (13) The obtained tantalum bars were pickled, dried and placed in a vacuum induction annealing furnace with a set temperature of about 1200-1450°C and a vacuum degree of 10 -3 Pa, keep warm for 0.5-2 hours and then cool in the furnace;

[0048] (14) subjecting the annealed tantalum strip to high temperature gas phase oxidation, with the temperature set at 750-890° C., introducing oxygen, keeping the temperature for 1.5-3 minutes, and then cooling the furnace; and

[0049] (15) The oxidized tantalum bars are drawn in a continuous wire drawing machine, using liquid lubricants and tungsten steel wire drawing dies, with the sizing zone set at about 10-20%, and the final tantalum wire products are drawn according to the different specifications of the users.

[0050] Example 1

[0051] Select the loose specific gravity as 3.0g / cm 3 Tantalum powder with an average particle size of 5 microns, rare earth element yttrium is selected, the purity is 99.99%, the mass ratio of tantalum powder to yttrium powder is 99:1, mixed in a mixer for 2 hours, loaded into a latex head, pressed into a blank at a pressure of 150MPa in a cold isostatic press, and then loaded into a vertical melting sintering furnace, the high temperature holding point is 67% of the melting point of tantalum, the high temperature holding time is 2 hours, the sintered blank is loaded into a hydrogenation furnace, according to the holding temperature of 800℃, the holding time is 2 hours, and then the hydrogenated blank is placed in a jaw crusher for powdering, and all the produced tantalum powder is sieved through a 200-mesh sieve to obtain yttrium-doped mother alloy tantalum powder. Then the mother alloy tantalum powder is loaded into a deoxidation furnace, loaded with magnesium powder, and kept warm for 2 hours; the mother alloy tantalum powder after deoxidation is pickled, and then rinsed in pure water; finally, the rinsed mother alloy tantalum powder is dried in an oven to obtain the final mother alloy tantalum powder.

[0052] Select the loose specific gravity as 3.5g / cm 3 Tantalum powder with an average particle size of 5.0 microns is selected, and yttrium-doped master alloy tantalum powder is selected so that the mass ratio of tantalum powder to yttrium-doped master alloy tantalum powder is 98:2. The mixture is mixed in a mixer for 30 minutes, loaded into a latex head, and pressed into a blank at a pressure of 210MPa in a cold isostatic press. The blank is then loaded into a vacuum induction pre-sintering furnace with a high temperature holding point of 1950°C for 1.5 hours. After being taken out of the furnace, the blank is loaded into a vertical melting sintering furnace with a high temperature holding point of 2550°C for 2 hours. The tantalum blank after vertical melting sintering is rolled for multiple passes to obtain tantalum bars, and the rolling pass processing rate is 15%; the obtained tantalum bars are pickled, dried, and loaded into a vacuum induction annealing furnace with a set temperature of about 1400°C and a vacuum degree maintained at 10 -3 Pa or above, and keep warm for 2 hours; the annealed tantalum strip is subjected to high-temperature gas phase oxidation, the temperature is set to 860°C, oxygen is introduced, and the heat is kept for 1.5 minutes; the oxidized tantalum strip is drawn in a continuous wire drawing machine, using liquid lubricant and tungsten steel drawing die, the sizing zone is set at 15%, and the final tantalum wire product with a diameter of 0.29 mm is drawn.

[0053] Product (diameter: 0.29mm) tensile strength data and elongation

[0054] Number of detections <![CDATA[Tensile strength kgf / mm 2 > Elongation % 1 108 1.2 2 106 1.3 3 106 1.1 4 108 1.2 5 109 1.5 6 108 1.3 7 108 1.5 8 107 1.2 9 107 1.2 10 107 1.2

[0055] Tantalum wire anti-brittleness test data. This test uses capacitor-grade tantalum powder (20,000 specific volume) and tantalum wire (diameter: 0.29mm) to be pressed into an anode block according to a molding process. The depth of the tantalum wire buried in the anode block is about 1 / 3 of the anode block. The formed anode block is sintered at 1700℃, and then the tantalum wire exposed outside the anode block is subjected to a bending test until it breaks. The number of bends is expressed as follows;

[0056] Number of detections Anti-brittleness times 1 4 2 4 3 4 4 4 5 4 6 5 7 5 8 5 9 4 10 4

[0057] Example 2

[0058] Select the loose specific gravity as 4.0g / cm 3 The tantalum powder has an average particle size of 7.5 microns, and the element silicon is selected with a purity of 99.99%. The ratio of tantalum powder to silicon powder is 98.5:1.5. The materials are mixed in a mixer for 2 hours, loaded into a latex head, and pressed into a blank at a pressure of 210MPa in a cold isostatic press. Then, the blank is loaded into a vertical melting sintering furnace, and the high temperature holding point is 84% ​​of the melting point of tantalum. The high temperature holding time is 2 hours. The sintered blank is loaded into a hydrogenation furnace, and hydrogenated at a temperature of 800°C for a holding time of 2 hours. Then, the hydrogenated blank is placed in a jaw crusher for powdering. All the produced tantalum powders are sieved with a 200-mesh sieve to obtain silicon-doped master alloy tantalum powder. Then, the master alloy tantalum powder is loaded into a deoxidation furnace, loaded with magnesium powder, and kept warm for 2 hours; the master alloy tantalum powder after deoxidation is pickled, and then rinsed in pure water; finally, the rinsed master alloy tantalum powder is dried in an oven to obtain the final master alloy tantalum powder.

[0059] Select the loose specific gravity as 3.5g / cm 3 Tantalum powder with an average particle size of 5.0 microns is selected. Silicon-doped master alloy tantalum powder is selected. The mass ratio of tantalum powder to silicon-doped master alloy tantalum powder is 98:2. The materials are mixed in a mixer for 60 minutes, loaded into a latex head, and pressed into a blank at a pressure of 210MPa in a cold isostatic press. Then, the blank is loaded into a vacuum induction pre-sintering furnace, the high temperature holding point is 1950°C, and the blank is kept warm for 1.5 hours. After being taken out of the furnace, it is loaded into a vertical melting sintering furnace, the high temperature holding point is 2550°C, and the blank is kept warm for 2 hours. The tantalum blank after vertical melting sintering is rolled for multiple passes to obtain tantalum bars, and the rolling pass processing rate is 15%; the obtained tantalum bars are pickled, dried, and loaded into a vacuum induction annealing furnace, the set temperature is about 1400°C, and the vacuum degree is maintained at 10 -3 Pa or above, and keep warm for 2 hours; the annealed tantalum strip is subjected to high-temperature gas phase oxidation, the temperature is set to 860°C, oxygen is introduced, and the heat is kept for 1.5 minutes; the oxidized tantalum strip is drawn in a continuous wire drawing machine, using liquid lubricant and tungsten steel drawing die, the sizing zone is set at 15%, and the final tantalum wire product with a diameter of 0.29 mm is drawn.

[0060] Product (diameter: 0.29mm) tensile strength data and elongation

[0061] Number of detections <![CDATA[Tensile strength kgf / mm 2 > Elongation % 1 120 2.2 2 121 2.3 3 119 1.9 4 120 1.9 5 121 1.9 6 119 1.9 7 120 1.9 8 120 2.2 9 121 2.2 10 120 1.9

[0062] Tantalum wire anti-brittleness test data. This test uses capacitor-grade tantalum powder (20,000 specific volume) and tantalum wire (diameter: 0.29mm) to be pressed into an anode block according to a molding process. The depth of the tantalum wire buried in the anode block is about 1 / 3 of the anode block. The formed anode block is sintered at 1700℃, and then the tantalum wire exposed outside the anode block is subjected to a bending test until it breaks. The number of bends is expressed as follows;

[0063] Number of detections Anti-brittleness times 1 5 2 5 3 5 4 5 5 6 6 5 7 5 8 5 9 4 10 5

[0064] The DOE full factorial experimental design scheme was used to carry out the test verification, and all master alloy powders containing a single rare earth element or silicon were used. The test results under different conditions were statistically shown in the following table (Note: The conditions not listed in Examples 3-67 belong to conventional process conditions and are similar to the conditions described in Examples 1-2 above. In order to avoid redundancy, they are not recorded in this article):

[0065]

[0066]

[0067] Embodiment 68

[0068] Select the loose specific gravity as 3.5g / cm 3 Tantalum powder with an average particle size of 5.0 microns is selected. The yttrium-doped and silicon-doped master alloy tantalum powders prepared in Examples 1 and 2 are selected. The mass ratio of tantalum powder to yttrium-doped master alloy and silicon-doped master alloy tantalum powder is 96:2:2. The mixture is mixed in a mixer for 60 minutes, loaded into a latex head, and pressed into a blank at a pressure of 210 MPa in a cold isostatic press. The blank is then loaded into a vacuum induction pre-sintering furnace with a high temperature holding point of 1950°C for 1.5 hours. After being taken out of the furnace, the blank is loaded into a vertical melting sintering furnace with a high temperature holding point of 2550°C for 2 hours. The tantalum blank after vertical melting sintering is rolled for multiple passes to obtain tantalum bars, and the rolling pass processing rate is 15%; the obtained tantalum bars are pickled, dried, and loaded into a vacuum induction annealing furnace with a set temperature of about 1400°C and a vacuum degree maintained at 10 -3 Pa or above, and keep warm for 2 hours; the annealed tantalum strip is subjected to high-temperature gas phase oxidation, the temperature is set to 860°C, oxygen is introduced, and the heat is kept for 1.5 minutes; the oxidized tantalum strip is drawn in a continuous wire drawing machine, using liquid lubricant and tungsten steel drawing die, the sizing zone is set at 15%, and the final tantalum wire product with a diameter of 0.15 mm is drawn.

[0069] Product (diameter: 0.15mm) tensile strength data and elongation

[0070] Number of detections <![CDATA[Tensile strength kgf / mm 2 > Elongation % 1 160 1.1 2 161 1.1 3 159 1.1 4 160 1.2 5 161 1.1 6 158 1.3 7 160 1.1 8 160 1.2 9 161 1.1 10 160 1.2

[0071] Tantalum wire anti-brittleness test data. This test uses capacitor-grade tantalum powder (20,000 specific volume) and tantalum wire (diameter: 0.15mm) to be pressed into an anode block according to a molding process. The depth of the tantalum wire buried in the anode block is about 1 / 3 of the anode block. The formed anode block is sintered at 1700℃, and then the tantalum wire exposed outside the anode block is subjected to a bending test until it breaks. The number of bends is expressed as follows;

[0072]

[0073]

[0074] Embodiment 69

[0075] Select the loose specific gravity as 3.5g / cm 3 Tantalum powder with an average particle size of 5.0 microns is selected. The yttrium-doped and silicon-doped master alloy tantalum powders of Examples 1 and 2 are selected. The mass ratio of tantalum powder to yttrium-doped master alloy and silicon-doped master alloy tantalum powder is 98:1:1. The mixture is mixed in a mixer for 30 minutes, loaded into a latex head, and pressed into a blank at a pressure of 210 MPa in a cold isostatic press. The blank is then loaded into a vacuum induction pre-sintering furnace with a high temperature holding point of 1950°C for 1.5 hours. After being taken out of the furnace, the blank is loaded into a vertical melting sintering furnace with a high temperature holding point of 2550°C for 2 hours. The tantalum blank after vertical melting sintering is rolled for multiple passes to obtain tantalum bars, and the rolling pass processing rate is 15%; the obtained tantalum bars are pickled, dried, and loaded into a vacuum induction annealing furnace with a set temperature of about 1400°C and a vacuum degree maintained at 10 -3 Pa or above, and keep warm for 2 hours; the annealed tantalum strip is subjected to high-temperature gas phase oxidation, the temperature is set to 860°C, oxygen is introduced, and the heat is kept for 1.5 minutes; the oxidized tantalum strip is drawn in a continuous wire drawing machine, using liquid lubricant and tungsten steel drawing die, the sizing zone is set at 15%, and the final tantalum wire product with a diameter of 0.29 mm is drawn.

[0076] Product (diameter: 0.29mm) tensile strength data and elongation

[0077] Number of detections <![CDATA[Tensile strength kgf / mm 2 > Elongation % 1 130 1.2 2 132 1.2 3 129 1.1 4 130 1.3 5 131 1.3 6 128 1.3 7 130 1.2 8 132 1.2 9 131 1.2 10 130 1.2

[0078] Tantalum wire anti-brittleness test data. This test uses capacitor-grade tantalum powder (20,000 specific volume) and tantalum wire (diameter: 0.29mm) to be pressed into an anode block according to a molding process. The depth of the tantalum wire buried in the anode block is about 1 / 3 of the anode block. The formed anode block is sintered at 1700℃, and then the tantalum wire exposed outside the anode block is subjected to a bending test until it breaks. The number of bends is expressed as follows;

[0079] Number of detections Anti-brittleness times 1 5 2 5 3 5 4 5 5 6 6 5 7 5 8 5 9 5 10 5

[0080] Embodiment 70

[0081] Select the loose specific gravity as 3.3g / cm 3 Tantalum powder with an average particle size of 5.5 microns is selected. The yttrium-doped and silicon-doped master alloy tantalum powders of Examples 1 and 2 are selected. The mass ratio of tantalum powder to yttrium-doped master alloy and silicon-doped master alloy tantalum powder is 98:1:1. The mixture is mixed in a mixer for 30 minutes, loaded into a latex head, and pressed into a blank at a pressure of 210 MPa in a cold isostatic press. The blank is then loaded into a vacuum induction pre-sintering furnace with a high temperature holding point of 1950°C for 1.5 hours. After being taken out of the furnace, the blank is loaded into a vertical melting sintering furnace with a high temperature holding point of 2550°C for 2 hours. The tantalum blank after vertical melting sintering is rolled for multiple passes to obtain tantalum bars, and the rolling pass processing rate is 15%; the obtained tantalum bars are pickled, dried, and loaded into a vacuum induction annealing furnace with a set temperature of about 1400°C and a vacuum degree maintained at 10 -3 Pa or above, and keep warm for 2 hours; the annealed tantalum strip is subjected to high-temperature gas phase oxidation, the temperature is set to 860°C, oxygen is introduced, and the heat is kept for 1.5 minutes; the oxidized tantalum strip is drawn in a continuous wire drawing machine, using liquid lubricant and tungsten steel drawing die, the sizing zone is set at 15%, and the final tantalum wire product with a diameter of 0.4 mm is drawn.

[0082] Product (diameter: 0.4mm) tensile strength data and elongation

[0083]

[0084]

[0085] Tantalum wire anti-brittleness test data. This test uses capacitor-grade tantalum powder (20,000 specific volume) and tantalum wire (diameter: 0.4mm) to be pressed into an anode block according to a molding process. The depth of the tantalum wire buried in the anode block is about 1 / 3 of the anode block. The formed anode block is sintered at 1700℃, and then the tantalum wire exposed outside the anode block is subjected to a bending test until it breaks. The number of bends is expressed as follows;

[0086] Number of detections Anti-brittleness times 1 5 2 5 3 5 4 6 5 5 6 5 7 5 8 5 9 6 10 5

[0087] The typical grain size photograph of the tantalum wire prepared from the mixture of master alloy tantalum powder and tantalum powder in Example 1-70 under 1700°C / 60 minutes annealing conditions is shown in FIG. Figure 1 As shown in the figure, it can be seen that after doping with master alloy tantalum powder, the grain size is uniform, indicating that the distribution of rare earth elements is uniform, which will ensure the uniform tensile strength of the tantalum wire and the consistent number of brittle wire folding.

[0088] Comparative Example 1

[0089] Select the loose specific gravity as 3.3g / cm 3 Tantalum powder with an average particle size of 5.5 microns is loaded into a latex cap, pressed into a blank at a pressure of 210MPa in a cold isostatic press, and then loaded into a vacuum induction pre-sintering furnace, with a high temperature holding point of 1950°C for 1.5 hours, and then loaded into a vertical melting sintering furnace, with a high temperature holding point of 2550°C for 2 hours. The tantalum blank after vertical melting sintering is rolled multiple times to obtain tantalum bars, and the rolling pass processing rate is 15%; the obtained tantalum bars are pickled, dried, and loaded into a vacuum induction annealing furnace, the set temperature is about 1260°C, and the vacuum degree is maintained at 10 -3 Pa or above, and keep warm for 2 hours; the annealed tantalum strip is subjected to high-temperature gas phase oxidation, the temperature is set to 850°C, oxygen is introduced, and the heat is kept for 1.5 minutes; the oxidized tantalum strip is drawn in a continuous wire drawing machine, using liquid lubricant and tungsten steel drawing die, the sizing zone is set at 15%, and the final tantalum wire product with a diameter of 0.29 mm is drawn.

[0090] Product (diameter: 0.29mm) tensile strength data and elongation

[0091] Number of detections <![CDATA[Tensile strength kgf / mm 2 > Elongation % 1 79 3.4 2 72 3.3 3 75 3.2 4 75 3.5 5 76 2.3 6 76 3.4 7 73 3.2 8 76 3.3 9 81 3.4 10 75 3.2

[0092] Tantalum wire anti-brittleness test data. This test uses capacitor-grade tantalum powder (20,000 specific volume) and tantalum wire (diameter: 0.29mm) to be pressed into an anode block according to a molding process. The depth of the tantalum wire buried in the anode block is about 1 / 3 of the anode block. The formed anode block is sintered at 1700℃, and then the tantalum wire exposed outside the anode block is subjected to a bending test until it breaks. The number of bends is expressed as follows;

[0093] Number of detections Anti-brittleness times 1 3 2 4 3 3 4 3 5 4 6 3 7 3 8 3 9 4 10 3

[0094] Comparative Example 2

[0095] Select the loose specific gravity as 3.5g / cm 3 Tantalum powder with an average particle size of 5.0 microns is selected, and pure yttrium powder with a purity of 99.99% is selected. The mass ratio of tantalum powder to yttrium powder is 9998:2. The materials are mixed in a mixer for 30 minutes, loaded into a latex head, and pressed into a blank at a pressure of 210MPa in a cold isostatic press. Then, the blank is loaded into a vacuum induction pre-sintering furnace, and the high temperature holding point is 1950°C, and the blank is kept warm for 1.5 hours. After being taken out of the furnace, it is loaded into a vertical melting sintering furnace, and the high temperature holding point is 2550°C, and the blank is kept warm for 2 hours. The tantalum blank after vertical melting sintering is rolled for multiple passes to obtain tantalum bars, and the rolling pass processing rate is 15%; the obtained tantalum bars are pickled, dried, and loaded into a vacuum induction annealing furnace, the set temperature is about 1400°C, and the vacuum degree is maintained at 10 -3Pa or above, and keep warm for 2 hours; the annealed tantalum strip is subjected to high-temperature gas phase oxidation, the temperature is set to 860°C, oxygen is introduced, and the heat is kept for 1.5 minutes; the oxidized tantalum strip is drawn in a continuous wire drawing machine, using liquid lubricant and tungsten steel drawing die, the sizing zone is set at 15%, and the final tantalum wire product with a diameter of 0.29 mm is drawn.

[0096] Product (diameter: 0.29mm) tensile strength data and elongation

[0097] Number of detections <![CDATA[Tensile strength kgf / mm 2 > Elongation % 1 137 1.2 2 112 3.2 3 109 3.1 4 120 2.3 5 115 1.3 6 128 2.3 7 110 3.2 8 112 3.2 9 131 1.5 10 130 1.7

[0098] Tantalum wire anti-brittleness test data. This test uses capacitor-grade tantalum powder (20,000 specific volume) and tantalum wire (diameter: 0.29mm) to be pressed into an anode block according to a molding process. The depth of the tantalum wire buried in the anode block is about 1 / 3 of the anode block. The formed anode block is sintered at 1700℃, and then the tantalum wire exposed outside the anode block is subjected to a bending test until it breaks. The number of bends is expressed as follows;

[0099] Number of detections Anti-brittleness times 1 6 2 3 3 3 4 5 5 4 6 5 7 4 8 5 9 6 10 5

[0100] Comparative Example 3

[0101] Select the loose specific gravity as 3.3g / cm 3 Tantalum powder with an average particle size of 5.5 microns is selected, pure silicon powder with a purity of 99.99%, and the mass ratio of tantalum powder to silicon powder is 9998:2. The materials are mixed in a mixer for 60 minutes, loaded into a latex head, and pressed into a blank at a pressure of 210MPa in a cold isostatic press, and then loaded into a vacuum induction pre-sintering furnace, the high temperature holding point is 1950℃, and the heat is kept for 1.5 hours. After being taken out of the furnace, it is loaded into a vertical melting sintering furnace, the high temperature holding point is 2550℃, and the heat is kept for 2 hours. The tantalum blank after vertical melting sintering is rolled for multiple passes to obtain tantalum bars, and the rolling pass processing rate is 15%; the obtained tantalum bars are pickled, dried, and loaded into a vacuum induction annealing furnace, the set temperature is about 1400℃, and the vacuum degree is maintained at 10 -3 Pa or above, and keep warm for 2 hours; the annealed tantalum strip is subjected to high-temperature gas phase oxidation, the temperature is set to 860°C, oxygen is introduced, and the heat is kept for 1.5 minutes; the oxidized tantalum strip is drawn in a continuous wire drawing machine, using liquid lubricant and tungsten steel drawing die, the sizing zone is set at 15%, and the final tantalum wire product with a diameter of 0.29 mm is drawn.

[0102] Product (diameter: 0.29mm) tensile strength data and elongation

[0103] Number of detections <![CDATA[Tensile strength kgf / mm 2 > Elongation % 1 118 1.1 2 92 2.3 3 105 2.3 4 113 1.8 5 108 1.9 6 99 2.4 7 110 1.9 8 99 2.4 9 120 1.3 10 119 1.6

[0104] Tantalum wire anti-brittleness test data. This test uses capacitor-grade tantalum powder (20,000 specific volume) and tantalum wire (diameter: 0.29mm) to be pressed into an anode block according to a molding process. The depth of the tantalum wire buried in the anode block is about 1 / 3 of the anode block. The formed anode block is sintered at 1700℃, and then the tantalum wire exposed outside the anode block is subjected to a bending test until it breaks. The number of bends is expressed as follows;

[0105]

[0106]

[0107] Comparative Example 4

[0108] Select the loose specific gravity as 3.3g / cm 3 Tantalum powder with an average particle size of 5.5 microns is selected. Pure yttrium and silicon powder are selected with a purity of 99.99%. The mass ratio of tantalum powder to yttrium powder and silicon powder is 9996:2:2. The materials are mixed in a mixer for 30 minutes, loaded into a latex head, and pressed into a blank at a pressure of 210MPa in a cold isostatic press. Then, the blank is loaded into a vacuum induction pre-sintering furnace with a high temperature holding point of 1950°C for 1.5 hours. After being taken out of the furnace, it is loaded into a vertical melting sintering furnace with a high temperature holding point of 2550°C for 2 hours. The tantalum blank after vertical melting sintering is rolled for multiple passes to obtain tantalum bars, and the rolling pass processing rate is 15%; the obtained tantalum bars are pickled, dried, and loaded into a vacuum induction annealing furnace with a set temperature of about 1400°C and a vacuum degree maintained at 10 -3 Pa or above, and keep warm for 2 hours; the annealed tantalum strip is subjected to high-temperature gas phase oxidation, the temperature is set to 860℃, oxygen is introduced, and the heat is kept for 1.5 minutes; the oxidized tantalum strip is drawn in a continuous wire drawing machine, using liquid lubricant and tungsten steel drawing die, the sizing zone is set at 15%, and the final tantalum wire product with a diameter of 0.4mm is drawn according to the different specifications of users.

[0109] Product (diameter: 0.4mm) tensile strength data and elongation

[0110] Number of detections <![CDATA[Tensile strength kgf / mm 2 > Elongation % 1 128 1.2 2 122 2.3 3 101 2.3 4 99 3.2 5 131 1.4 6 109 1.6 7 130 1.2 8 109 1.7 9 127 1.1 10 114 3.3

[0111] Tantalum wire anti-brittleness test data. This test uses capacitor-grade tantalum powder (20,000 specific volume) and tantalum wire (diameter: 0.40mm) to be pressed into an anode block according to a molding process. The depth of the tantalum wire buried in the anode block is about 1 / 3 of the anode block. The formed anode block is sintered at 1700℃, and then the tantalum wire exposed outside the anode block is subjected to a bending test until it breaks. The number of bends is expressed as follows;

[0112] Number of detections Anti-brittleness times 1 5 2 4 3 3 4 3 5 5 6 4 7 5 8 4 9 5 10 4

[0113] Typical grain size photos of tantalum wires prepared from a direct mixture of yttrium powder and / or silicon powder and tantalum powder in Comparative Examples 2-4 under 1700°C / 60 minutes annealing conditions are shown in FIG. Figure 2 As shown in the figure, it can be seen that the grain sizes are different, indicating that the distribution of rare earth elements is uneven, which will lead to inconsistent tensile strength of tantalum wire and inconsistent number of brittle wire folding.

[0114] All features disclosed in this specification, or steps in all methods or processes disclosed, except mutually exclusive features and / or steps, can be combined in any manner.

[0115] Any feature disclosed in this specification, unless otherwise stated, can be replaced by other equivalent or alternative features with similar purposes. Unless otherwise stated, each feature is only an example of a series of equivalent or similar features.

[0116] Unless otherwise limited, all technical and scientific terms used herein have the same meanings commonly understood by those of ordinary skill in the art to which these exemplary embodiments belong. The terminology used in the description herein is only used to describe the exemplary embodiments and is not intended to limit the exemplary embodiments. Therefore, the overall inventive concept is not intended to be limited to the specific embodiments described herein. Although preferred methods and materials are described herein, other methods and materials similar or equivalent to those described herein may be used in the practice or testing of the present invention.

[0117] Unless otherwise indicated, all numbers used in the specification and claims expressing amounts of ingredients, chemical and molecular properties, reaction conditions, and the like are to be understood as being modified in all instances by the term "about". Therefore, unless indicated to the contrary, the numerical parameters set forth in the specification and the appended claims are approximate values ​​that may vary depending on the desired properties sought to be obtained by the exemplary embodiments herein. At least each numerical parameter should be interpreted in light of the number of significant figures and ordinary rounding techniques.

[0118] Although the numerical ranges and parameters describing the broad range of exemplary embodiments are approximate, the numerical values ​​described in the specific examples are reported as accurately as possible. However, any numerical value inherently contains certain errors that are necessarily produced by the standard deviation found in their respective test measurements. Each numerical range given throughout the specification and claims will include each narrower numerical range that falls within such a wider numerical range, as if such a narrower numerical range is also explicitly written out in this article. In addition, any numerical value reported in the examples can be used to define the upper or lower endpoints of the wider composition range disclosed herein.

Claims

1. A method for preparing a tantalum wire having improved brittleness resistance, the method comprising the following steps in sequence: (1) Tantalum powder and dopant powder are mixed to form a first mixture, wherein the dopant powder is rare earth element powder, germanium powder or silicon powder; (2) the first mixture is subjected to cold isostatic pressing to obtain a master alloy billet; (3) the master alloy billet is subjected to vertical melting sintering; (4) the master alloy billet after vertical melting sintering is subjected to hydrogenation and powdering to obtain a master alloy tantalum powder; (5) tantalum powder and one or more master alloy tantalum powders are mixed to form a second mixture; (6) the second mixture is used as a powder raw material to prepare tantalum wire.

2. The method according to claim 1, wherein in step (1), the tantalum powder and the dopant powder are mixed in a mass ratio of 99:1-98.5:1.

5.

3. The method according to claim 1, wherein in step (2), cold isostatic pressing is performed at a pressure of 150-210 MPa.

4. The method according to claim 1, wherein in step (3), the vertical melting sintering is performed by keeping the temperature at a high temperature holding point, and the high temperature holding point is 67-84% of the melting point of tantalum.

5. The method according to claim 1, wherein the hydrogenation in step (4) is carried out in the following manner: the mother alloy billet after vertical melting and sintering is loaded into a hydrogenation furnace, the furnace temperature is set to 800-950°C, hydrogen is introduced, and the furnace is kept warm.

6. The method according to claim 5, wherein the powder making in step (4) comprises the following steps: taking out the hydrogenated master alloy billet from the hydrogenation furnace, crushing it in a crusher, and obtaining the master alloy tantalum powder by screening.

7. The method according to claim 1 or 6, wherein the master alloy tantalum powder is a master alloy tantalum powder with a sieve size below 200 mesh.

8. The method according to claim 1, further comprising the following steps after step (4) and before step (5): loading the master alloy tantalum powder into a deoxidation furnace, loading magnesium powder, and keeping the temperature; acid-washing the deoxidized master alloy tantalum powder, and then rinsing it in pure water; and drying the rinsed master alloy tantalum powder in an oven.

9. The method according to claim 1, wherein in step (5), the tantalum powder and one or more master alloy tantalum powders are mixed so that the mass content of the rare earth element, germanium or silicon in the second mixture does not exceed 500 ppm.

10. The method according to claim 1, wherein the rare earth element is yttrium or cerium.

11. The method according to claim 1, wherein step (6) includes the following sub-steps: (6-1) cold isostatic pressing the second mixture to obtain a tantalum billet; (6-2) vertical melting sintering the tantalum billet; and (6-3) rolling and drawing the vertical melting sintered tantalum billet.

12. Tantalum wire with improved brittleness resistance produced by the method according to any one of claims 1 to 11.

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