Method of making tantalum wire with improved brittleness resistance and tantalum wire made by the method

Abstract

The present application provides a method for preparing tantalum wire with improved brittleness resistance, which comprises 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 blank; (3) vertical sintering the master alloy blank; (4) hydrogenating and powdering the vertical sintered master alloy blank to obtain master alloy tantalum powder; (5) mixing the tantalum powder and one or more kinds of master alloy tantalum powder to form a second mixture; (6) using the second mixture as a powder raw material to prepare tantalum wire. The present application also relates to tantalum wire with improved brittleness resistance prepared by the method.

Description

Technical Field

[0001] This invention relates to the field of tantalum or tantalum alloy processing technology, and more particularly to a method for preparing tantalum wire with improved resistance to brittleness and the tantalum wire prepared by the method. Background Technology

[0002] Conventional capacitor anode leads are undoped tantalum wires. However, due to current capacitor technology requirements, the sintering temperature of the anode block has significantly increased, resulting in a substantial increase in the grain size of the tantalum wires on the anode block. This allows harmful impurities from the tantalum powder in the anode block to easily diffuse into the tantalum wire, causing it to become brittle. For tantalum wire, brittleness resistance refers to the process of pressing capacitor-grade tantalum powder and tantalum wire into an anode block using a molding process, with the tantalum wire embedded to approximately one-third of the anode block's depth. The molded anode block is then sintered at 1500-1900℃, and the exposed tantalum wire is subjected to a bending test until it breaks. The number of bends indicates the tantalum wire's brittleness resistance.

[0003] Therefore, to solve this problem, a certain amount of rare earth elements are added to the tantalum wire. These rare earth elements are distributed on the grain boundaries (which helps to refine the tantalum wire grains) and inhibit the growth of tantalum wire grains at high temperatures. This method is called doping. The traditional tantalum wire doping method is to directly add rare earth metals to tantalum powder, and then mix, form isostatic pressing, and sinter to produce tantalum wire blanks. The blanks are then rolled and drawn to produce capacitor-grade tantalum wires.

[0004] In his paper "Process Methods for Improving the Properties of Tantalum Wire," published in Volume 30, Issue 2 of *Rare Metals and Hard Alloys* (June 2002), Cao Hansong studied the influence of doping on the individual properties of tantalum wire. The results showed that whether doped with trace element A or trace element B, as long as the doping amount is appropriate and uniformly distributed, the brittleness resistance of tantalum wire can be improved. That is, the brittleness resistance of doped tantalum wire is far superior to that of pure tantalum wire. In particular, the brittleness resistance of tantalum wire doped with both A and B is even more outstanding. Simultaneous doping of A and B into tantalum wire can inhibit grain growth and refine the grain size. 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 sintered to produce a product with high brittleness resistance. The disadvantage of this method is that because the loose specific gravity of tantalum powder and elemental rare earth elements is large, the elemental rare earth elements will float on the tantalum powder during the mixing process after addition, and the material cannot be completely mixed evenly. The resulting tantalum wire often has problems such as uneven doping distribution, uneven grain size, fluctuation in tensile strength, and poor consistency in brittleness resistance.

[0005] Furthermore, Chinese patent CN 111910097 B discloses a method for preparing silicon-doped tantalum wire. Unlike traditional solid-mix silicon doping, this invention advances the silicon doping step to the crystallization step of potassium fluorotantalate preparation. Utilizing the property that silicon is readily soluble in hydrofluoric acid, while potassium fluorosilicate has very low solubility in the system, liquid silicon doping is employed, achieving uniform silicon incorporation into the potassium fluorotantalate. When using this potassium fluorotantalate to produce tantalum wire, silicon is not lost in subsequent processes such as reduction and melting, ultimately becoming uniformly incorporated into the tantalum wire. This method achieves uniform silicon incorporation, improving the performance of silicon-doped tantalum wire products. This is the reduction-tantalum powder crystallization doping method using potassium fluorotantalate. However, the tantalum powder produced by this method contains a large amount of fluoride salts, which greatly affects the performance of the tantalum powder. Therefore, after the tantalum powder is produced, it needs to be acid-washed and water-washed. Since the F- ions in the fluoride salts will form hydrofluoric acid when they encounter the hydrogen ions in the hydrochloric acid, and this hydrofluoric acid has a certain solubility for silicon, 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 is needed to prepare tantalum wire with improved brittle resistance. The tantalum wire prepared by this method has high brittle resistance, can effectively improve the uniformity of tantalum blank grains, and improve the tensile strength, elongation and other properties of tantalum wire, thus solving the problem of poor brittle resistance of tantalum wire during capacitor sintering. Summary of the Invention

[0007] One technical problem this invention aims to solve is the brittleness of the tantalum wire anode block lead. Furthermore, another technical problem this invention aims to solve is the inconsistency in properties such as brittleness resistance, strength, and bendability caused by the uneven grain distribution within the tantalum wire after doping using traditional methods.

[0008] To address the above technical problems, the present invention provides the following technical solution:

[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 blank; (3) sintering the master alloy blank; (4) hydrogenating and pulverizing the sintered master alloy blank to obtain master alloy tantalum powder; (5) mixing tantalum powder and one or more master alloy tantalum powders to form a second mixture; (6) using the second mixture as a raw material to prepare tantalum wire.

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

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

[0012] Preferably, the sintering in step (3) is performed by holding at a high-temperature holding point, which is 67-84% of the melting point of tantalum. The melting point of tantalum is 2996℃. It should be noted that those skilled in the art can reasonably determine the holding time based on 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 as follows: the master alloy billet after vertical melting and sintering is loaded into a hydrogenation furnace, the furnace temperature is set to 800-950℃, hydrogen gas is introduced, and the temperature is maintained. It should be noted that those skilled in the art can reasonably determine the holding time based on the set furnace temperature. As a non-limiting example, the holding time is 1-3 hours.

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

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

[0016] Preferably, the process includes the following steps after step (4) and before step (5): loading the master alloy tantalum powder into a deoxidation furnace, loading magnesium powder, and holding it at a temperature (those skilled in the art can reasonably determine the holding time according to the deoxidation requirements. As a non-limiting example, the holding 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), tantalum powder and one or more master alloy tantalum powders are mixed such that the mass content of rare earth elements or silicon in the second mixture does not exceed 500 ppm, preferably not more than 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 loose specific gravity of the tantalum powder is 3.0-4.0 g / cm³. 3 The average particle size is between 5.0 and 7.5 micrometers.

[0020] Preferably, the tantalum powder in step (5) is metallurgical grade tantalum powder, and the loose specific gravity of the tantalum powder is 3.0-4.0 g / cm³. 3 The average particle size is between 5.0 and 7.5 micrometers.

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

[0022] It should be noted that the process of preparing tantalum wire from tantalum powder is a conventional technique in the art. In other words, those skilled in the art know how to perform step (6) of the above method, which uses the second mixture as a 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) sintering the tantalum billet; and (6-3) rolling and drawing the sintered tantalum billet.

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

[0024] As an example, in step (6-2), the tantalum billet is placed in a vacuum induction pre-sintering furnace for sintering, with the temperature set at approximately 1400-2000℃ and the vacuum level maintained at 10. -2 The tantalum billet is held at a temperature above 10 Pa for a period of time (the holding time can be reasonably determined by those skilled in the art based on the sintering temperature. As a non-limiting example, the holding time is 1-3 hours); then the tantalum billet is placed into a vacuum vertical melting sintering furnace, the temperature is set at about 2100-2600℃, and the vacuum degree is maintained at 10. -3 Keep warm for 0.5-2 hours at pressures above 100 Pa.

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

[0026] As an example, in step (6-3), the obtained tantalum strip is pickled, dried, and then placed in a vacuum induction annealing furnace. The temperature is set at approximately 1200-1450°C, and the vacuum level is maintained at 10. -3 Keep warm for 0.5-2 hours at pressures above 100 Pa.

[0027] As an example, in step (6-3), the annealed tantalum strip is subjected to high-temperature vapor phase oxidation at a temperature of 750-890℃, oxygen is introduced, and the temperature is maintained for 1.5-3 minutes.

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

[0029] Furthermore, the present invention provides a tantalum wire with improved resistance to brittleness, which is prepared according to the aforementioned method.

[0030] Compared with existing technologies, the method of this invention differs in that it first prepares an alloy powder of tantalum with rare earth elements, germanium, or silicon, referred to as master alloy tantalum powder. The rare earth elements, germanium, or silicon in the master alloy tantalum powder exist in alloy form with tantalum, and its loose bulk density is essentially the same as that of tantalum powder. Therefore, when the master alloy tantalum powder is mixed with tantalum powder, there is no stratification problem, ensuring the uniformity of doping. Through this process design, doped tantalum wires with uniform performance and excellent anti-brittleness properties are obtained. Attached Figure Description

[0031] Figure 1 These are typical grain size photographs of tantalum wires prepared from a mixture of master alloy tantalum powder and tantalum powder in Examples 1-70 under annealing conditions of 1700°C / 60 minutes; these grain size photographs show that the tantalum wires prepared by this method have fine and uniform grains.

[0032] Figure 2 These are typical grain size photographs of tantalum wires prepared from a direct mixture of yttrium powder and / or silicon powder with tantalum powder in Comparative Examples 2-4, under annealing conditions of 1700°C / 60 minutes. These grain size photographs show that the tantalum wires produced by this method have coarse and inhomogeneous grains. Detailed Implementation

[0033] To further understand the present invention, preferred embodiments are described below with reference to examples. However, 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 scope of protection of the present invention. In other words, the scope of protection of the present invention, constructed by the claims and their equivalents, is not limited to these embodiments.

[0034] Embodiments of the present invention provide a method for preparing tantalum wire with improved resistance to brittleness, 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 at a mass ratio of 99:1 to 98.5:1.5 to form a first mixture, wherein the tantalum powder is metallurgical grade tantalum powder with a loose specific gravity of 3.0-4.0 g / cm³. 3 The average particle size is between 5.0 and 7.5 micrometers.

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

[0037] (3) The master alloy billet is subjected to vertical melting sintering, which is carried out by holding at a high temperature holding point for 1-3 hours and then furnace cooling. The high temperature holding point is 67-84% of the melting point of tantalum, and the melting point of tantalum is 2996℃.

[0038] (4) Load the master alloy billet after vertical melting and sintering into the hydrogenation furnace, set the furnace temperature to 800-950℃, introduce hydrogen, keep it at the temperature for 1-3 hours, and then cool the furnace.

[0039] (5) Take out the hydrogenated master alloy billet from the hydrogenation furnace, crush it in a crusher, and obtain master alloy tantalum powder with a mesh size of less than 200 mesh by screening.

[0040] (6) Load the master alloy tantalum powder into the deoxidation furnace, add magnesium powder, keep it at the temperature for 1-3 hours, and then cool the furnace.

[0041] (7) Pickling the deoxidized tantalum powder of the master alloy is performed, and then rinsing is performed in pure water;

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

[0043] (9) Mix tantalum powder and master alloy tantalum powder for 30-60 minutes to form a second mixture, such that the mass content of rare earth elements, germanium, or silicon in the second mixture does not exceed 500 ppm, wherein the tantalum powder is metallurgical grade tantalum powder with a loose specific gravity of 3.0-4.0 g / cm³. 3 The average particle size is between 5.0 and 7.5 micrometers.

[0044] (10) The second mixture is subjected to cold isostatic pressing at a pressure of 150-210 MPa to obtain a tantalum billet;

[0045] (11) The tantalum billet is subjected to vertical melting sintering, wherein the tantalum billet is placed in a vacuum induction pre-sintering furnace for sintering, the temperature is set at about 1400-2000℃, and the vacuum degree is maintained at 10. -2 After holding at a temperature above 0.5-2 hours, the furnace is cooled. Then, the tantalum billet is loaded into a vacuum vertical melting sintering furnace, with the temperature set at approximately 2100-2600℃ and the vacuum maintained at 10. -3 Above Pa, hold at that temperature for 0.5-2 hours, then cool the furnace.

[0046] (12) The tantalum billet after vertical melting sintering is rolled in multiple passes to obtain tantalum bars, and the processing rate of each rolling pass is 10-20%.

[0047] (13) Pickle the obtained tantalum strip, dry it, and then put it into a vacuum induction annealing furnace. Set the temperature to about 1200-1450℃ and maintain the vacuum degree at 10. -3 Above Pa, hold at that temperature for 0.5-2 hours, then cool the furnace.

[0048] (14) The annealed tantalum bars are subjected to high-temperature vapor phase oxidation at a temperature of 750-890℃, with oxygen introduced and held at this temperature for 1.5-3 minutes before furnace cooling; and

[0049] (15) The oxidized tantalum strip is drawn in a continuous wire drawing machine. Liquid lubricant and tungsten steel wire drawing die are used. The sizing zone is set at about 10-20%. The final tantalum wire product is drawn according to the different specifications required by the user.

[0050] Example 1

[0051] Select a loose bulk density of 3.0 g / cm³. 3 Tantalum powder with an average particle size of 5 micrometers was selected, and yttrium, a rare earth element, with a purity of 99.99% was chosen. The mass ratio of tantalum powder to yttrium powder was 99:1. The mixture was mixed in a mixer for 2 hours, then loaded into a latex-coated die and pressed into a billet in a cold isostatic press under a pressure of 150 MPa. The billet was then placed in a vertical melting sintering furnace, where it was held at 67% of the melting point of tantalum for 2 hours. The sintered billet was then placed in a hydrogenation furnace and held at 800℃ for 2 hours. The hydrogenated billet was then placed in a jaw crusher for powdering. All the tantalum powder produced was passed through a 200-mesh sieve to obtain yttrium-doped master alloy tantalum powder. The master alloy tantalum powder was then placed in a deoxidation furnace with magnesium powder and held for 2 hours. The deoxidized master alloy tantalum powder was acid-washed and then rinsed in pure water. Finally, the rinsed master alloy tantalum powder was dried in an oven to obtain the final master alloy tantalum powder.

[0052] Select a loose bulk density of 3.5 g / cm³. 3 Tantalum powder with an average particle size of 5.0 micrometers was selected, and yttrium-doped master alloy tantalum powder was chosen, with a mass ratio of tantalum powder to yttrium-doped master alloy tantalum powder of 98:2. The mixture was stirred in a mixer for 30 minutes, then loaded into a latex-coated die, and pressed into a billet in a cold isostatic press under a pressure of 210 MPa. The billet was then placed in a vacuum induction pre-sintering furnace, held at 1950℃ for 1.5 hours, and then placed in a vertical melting sintering furnace, held at 2550℃ for 2 hours. The vertically melted tantalum billet was then rolled in multiple passes to obtain tantalum bars, with a rolling pass rate of 15%. The obtained tantalum bars were pickled, dried, and then placed in a vacuum induction annealing furnace at a temperature of approximately 1400℃, with the vacuum level maintained at 10. -3 The annealed tantalum strip is subjected to high-temperature vapor phase oxidation at 860℃, with oxygen introduced and held for 1.5 minutes. The oxidized tantalum strip is then drawn in a continuous wire drawing machine using liquid lubricant and tungsten steel wire drawing dies. The sizing zone is set at 15%, and a final tantalum wire product with a diameter of 0.29 mm is produced.

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

[0054] 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] The tantalum wire brittleness resistance test data were obtained by pressing capacitor-grade tantalum powder (20,000 specific capacitance) and tantalum wire (diameter: 0.29 mm) into an anode block using a molding process. The tantalum wire was buried in the anode block to a depth of approximately 1 / 3 of the anode block. The molded anode block was sintered at 1700℃, and then the tantalum wire exposed outside the anode block was subjected to a bending test until it broke. The number of bends is expressed as follows.

[0056] 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 a loose bulk density of 4.0 g / cm³. 3 Tantalum powder with an average particle size of 7.5 micrometers was selected, using elemental silicon with a purity of 99.99%. The ratio of tantalum powder to silicon powder was 98.5:1.5. The mixture was stirred in a mixer for 2 hours, then loaded into a latex-coated die and pressed into a billet in a cold isostatic press at 210 MPa. The billet was then placed in a vertical melting sintering furnace, held at 84% of the tantalum melting point for 2 hours. The sintered billet was then placed in a hydrogenation furnace and hydrogenated at 800℃ for 2 hours. The hydrogenated billet was then ground into powder using a jaw crusher. All the tantalum powder was sieved through a 200-mesh sieve to obtain silicon-doped master alloy tantalum powder. The master alloy tantalum powder was then placed in a deoxidation furnace with magnesium powder and held for 2 hours. The deoxidized master alloy tantalum powder was acid-washed and then rinsed in pure water. Finally, the rinsed master alloy tantalum powder was dried in an oven to obtain the final master alloy tantalum powder.

[0059] Select a loose bulk density of 3.5 g / cm³. 3 Tantalum powder with an average particle size of 5.0 micrometers was selected. Silicon-doped tantalum powder was used, with a mass ratio of 98:2. The mixture was stirred in a mixer for 60 minutes, then loaded into a latex-coated die and pressed into a billet in a cold isostatic press under a pressure of 210 MPa. The billet was then placed in a vacuum induction pre-sintering furnace, held at 1950℃ for 1.5 hours, and then transferred to a vertical melting sintering furnace, held at 2550℃ for 2 hours. The vertically melted tantalum billet was then rolled in multiple passes to obtain tantalum bars, with a rolling pass rate of 15%. The obtained tantalum bars were pickled, dried, and then placed in a vacuum induction annealing furnace at a set temperature of approximately 1400℃, with a vacuum level maintained at 10%. -3 The annealed tantalum strip is subjected to high-temperature vapor phase oxidation at 860℃, with oxygen introduced and held for 1.5 minutes. The oxidized tantalum strip is then drawn in a continuous wire drawing machine using liquid lubricant and tungsten steel wire drawing dies. The sizing zone is set at 15%, and a final tantalum wire product with a diameter of 0.29 mm is produced.

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

[0061] 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] The tantalum wire brittleness resistance test data were obtained by pressing capacitor-grade tantalum powder (20,000 specific capacitance) and tantalum wire (diameter: 0.29 mm) into an anode block using a molding process. The tantalum wire was buried in the anode block to a depth of approximately 1 / 3 of the anode block. The molded anode block was sintered at 1700℃, and then the tantalum wire exposed outside the anode block was subjected to a bending test until it broke. The number of bends is expressed as follows.

[0063] 1 5 2 5 3 5 4 5 5 6 6 5 7 5 8 5 9 4 10 5

[0064] Experimental verification was conducted using a DOE (Design of Experiments) full factorial design scheme. All experiments used master alloy powders containing a single rare earth element or silicon. The experimental results under different conditions are statistically analyzed in the table below (Note: The conditions not listed in Examples 3-67 are conventional process conditions and are similar to those described in Examples 1-2 above. They are not described in this document to avoid redundancy):

[0065]

[0066]

[0067] Example 68

[0068] Select a loose bulk density of 3.5 g / cm³. 3 The tantalum powder, with an average particle size of 5.0 micrometers, was selected from yttrium-doped and silicon-doped master alloy tantalum powders prepared in Examples 1 and 2. The mass ratio of tantalum powder to yttrium-doped and silicon-doped master alloy tantalum powders was 96:2:2. The mixture was mixed in a mixer for 60 minutes, then loaded into a latex-coated die, and pressed into a billet in a cold isostatic press under a pressure of 210 MPa. The billet was then placed in a vacuum induction pre-sintering furnace, held at a high temperature of 1950°C for 1.5 hours, and then placed in a vertical melting sintering furnace, held at a high temperature of 2550°C for 2 hours. The tantalum billet after vertical melting sintering was rolled in multiple passes to obtain tantalum bars, with a rolling pass rate of 15%. The obtained tantalum bars were pickled, dried, and then placed in a vacuum induction annealing furnace at a set temperature of approximately 1400°C, with the vacuum degree maintained at 10. -3 The annealed tantalum strip is subjected to high-temperature vapor phase oxidation at 860℃, with oxygen introduced and held for 1.5 minutes. The oxidized tantalum strip is then drawn in a continuous wire drawing machine using liquid lubricant and tungsten steel wire drawing dies. The sizing zone is set at 15%, and a final tantalum wire product with a diameter of 0.15mm is produced.

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

[0070] 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] The tantalum wire brittleness resistance test data were obtained by pressing capacitor-grade tantalum powder (20,000 specific capacitance) and tantalum wire (diameter: 0.15 mm) into an anode block using a molding process. The tantalum wire was buried in the anode block to a depth of approximately 1 / 3 of the anode block. The molded anode block was sintered at 1700℃, and then the tantalum wire exposed outside the anode block was subjected to a bending test until it broke. The number of bends is expressed as follows.

[0072]

[0073]

[0074] Example 69

[0075] Select a loose bulk density of 3.5 g / cm³. 3 The tantalum powder, with an average particle size of 5.0 micrometers, was selected from yttrium-doped and silicon-doped master alloy tantalum powders of Examples 1 and 2. The mass ratio of tantalum powder to yttrium-doped and silicon-doped master alloy tantalum powders was 98:1:1. The mixture was mixed in a mixer for 30 minutes, then loaded into a latex-coated die, and pressed into a billet in a cold isostatic press under a pressure of 210 MPa. The billet was then placed in a vacuum induction pre-sintering furnace, held at a high temperature of 1950°C for 1.5 hours, and then placed in a vertical melting sintering furnace, held at a high temperature of 2550°C for 2 hours. The tantalum billet after vertical melting sintering was rolled in multiple passes to obtain tantalum bars, with a rolling pass rate of 15%. The obtained tantalum bars were pickled, dried, and then placed in a vacuum induction annealing furnace at a set temperature of approximately 1400°C, with the vacuum degree maintained at 10. -3 The annealed tantalum strip is subjected to high-temperature vapor phase oxidation at 860℃, with oxygen introduced and held for 1.5 minutes. The oxidized tantalum strip is then drawn in a continuous wire drawing machine using liquid lubricant and tungsten steel wire drawing dies. The sizing zone is set at 15%, and a final tantalum wire product with a diameter of 0.29 mm is produced.

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

[0077] 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] The tantalum wire brittleness resistance test data were obtained by pressing capacitor-grade tantalum powder (20,000 specific capacitance) and tantalum wire (diameter: 0.29 mm) into an anode block using a molding process. The tantalum wire was buried in the anode block to a depth of approximately 1 / 3 of the anode block. The molded anode block was sintered at 1700℃, and then the tantalum wire exposed outside the anode block was subjected to a bending test until it broke. The number of bends is expressed as follows.

[0079] 1 5 2 5 3 5 4 5 5 6 6 5 7 5 8 5 9 5 10 5

[0080] Example 70

[0081] Select a loose bulk density of 3.3 g / cm³. 3 The tantalum powder, with an average particle size of 5.5 micrometers, was selected from yttrium-doped and silicon-doped master alloy tantalum powders of Examples 1 and 2. The mass ratio of tantalum powder to yttrium-doped and silicon-doped master alloy tantalum powders was 98:1:1. The mixture was mixed in a mixer for 30 minutes, then loaded into a latex-coated die, and pressed into a billet in a cold isostatic press under a pressure of 210 MPa. The billet was then placed in a vacuum induction pre-sintering furnace, held at a high temperature of 1950°C for 1.5 hours, and then placed in a vertical melting sintering furnace, held at a high temperature of 2550°C for 2 hours. The tantalum billet after vertical melting sintering was rolled in multiple passes to obtain tantalum bars, with a rolling pass rate of 15%. The obtained tantalum bars were pickled, dried, and then placed in a vacuum induction annealing furnace at a set temperature of approximately 1400°C, with the vacuum degree maintained at 10. -3 The annealed tantalum strip is subjected to high-temperature vapor phase oxidation at 860℃, with oxygen introduced and held for 1.5 minutes. The oxidized tantalum strip is then drawn in a continuous wire drawing machine using liquid lubricant and tungsten steel wire drawing dies. The sizing zone is set at 15%, and a final tantalum wire product with a diameter of 0.4mm is produced.

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

[0083]

[0084]

[0085] The tantalum wire brittleness resistance test data were obtained by pressing capacitor-grade tantalum powder (20,000 specific capacitance) and tantalum wire (diameter: 0.4 mm) into an anode block using a molding process. The tantalum wire was buried in the anode block to a depth of approximately 1 / 3 of the anode block. The molded anode block was sintered at 1700℃, and then the tantalum wire exposed outside the anode block was subjected to a bending test until it broke. The number of bends is expressed as follows.

[0086] 1 5 2 5 3 5 4 6 5 5 6 5 7 5 8 5 9 6 10 5

[0087] Typical grain size photographs of tantalum wires prepared from a mixture of master alloy tantalum powder and tantalum powder in Examples 1-70 under annealing conditions of 1700℃ / 60 minutes are shown below. Figure 1 As shown in the figure, after doping with tantalum powder from the master alloy, the grain size is uniform, indicating that the rare earth elements are evenly distributed, which will ensure that the tensile strength of the tantalum wire is uniform and the number of brittle wire bending cycles is consistent.

[0088] Comparative Example 1

[0089] Select a loose bulk density of 3.3 g / cm³. 3 Tantalum powder with an average particle size of 5.5 micrometers was loaded into a latex-coated head and pressed into a billet in a cold isostatic press under a pressure of 210 MPa. The billet was then placed in a vacuum induction pre-sintering furnace, held at 1950°C for 1.5 hours, and then transferred to a vertical melting sintering furnace, held at 2550°C for 2 hours. The vertically melted tantalum billet was then rolled in multiple passes to obtain tantalum bars, with a rolling pass rate of 15%. The obtained tantalum bars were pickled, dried, and then placed in a vacuum induction annealing furnace at a temperature of approximately 1260°C, with the vacuum level maintained at 10. -3 The annealed tantalum strip is subjected to high-temperature vapor phase oxidation at 850°C, with oxygen introduced and held for 1.5 minutes. The oxidized tantalum strip is then drawn in a continuous wire drawing machine using liquid lubricant and tungsten steel wire drawing dies. The sizing zone is set at 15%, and a final tantalum wire product with a diameter of 0.29 mm is produced.

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

[0091] 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] The tantalum wire brittleness resistance test data were obtained by pressing capacitor-grade tantalum powder (20,000 specific capacitance) and tantalum wire (diameter: 0.29 mm) into an anode block using a molding process. The tantalum wire was buried in the anode block to a depth of approximately 1 / 3 of the anode block. The molded anode block was sintered at 1700℃, and then the tantalum wire exposed outside the anode block was subjected to a bending test until it broke. The number of bends is expressed as follows.

[0093] 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 a loose bulk density of 3.5 g / cm³. 3 Tantalum powder with an average particle size of 5.0 micrometers and pure yttrium powder with a purity of 99.99% were selected. The mass ratio of tantalum powder to yttrium powder was 9998:2. The mixture was mixed in a mixer for 30 minutes, then loaded into a latex head and pressed into a billet in a cold isostatic press under a pressure of 210 MPa. The billet was then placed in a vacuum induction pre-sintering furnace and held at a high temperature of 1950℃ for 1.5 hours. After being removed from the furnace, it was placed in a vertical melting sintering furnace and held at a high temperature of 2550℃ for 2 hours. The tantalum billet after vertical melting sintering was rolled in multiple passes to obtain tantalum bars, with a rolling pass rate of 15%. The obtained tantalum bars were pickled, dried, and then placed in a vacuum induction annealing furnace at a set temperature of approximately 1400℃ and a vacuum degree maintained at 10. -3The annealed tantalum strip is subjected to high-temperature vapor phase oxidation at 860℃, with oxygen introduced and held for 1.5 minutes. The oxidized tantalum strip is then drawn in a continuous wire drawing machine using liquid lubricant and tungsten steel wire drawing dies. The sizing zone is set at 15%, and a final tantalum wire product with a diameter of 0.29 mm is produced.

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

[0097] 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] The tantalum wire brittleness resistance test data were obtained by pressing capacitor-grade tantalum powder (20,000 specific capacitance) and tantalum wire (diameter: 0.29 mm) into an anode block using a molding process. The tantalum wire was buried in the anode block to a depth of approximately 1 / 3 of the anode block. The molded anode block was sintered at 1700℃, and then the tantalum wire exposed outside the anode block was subjected to a bending test until it broke. The number of bends is expressed as follows.

[0099] 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 a loose bulk density of 3.3 g / cm³. 3 Tantalum powder with an average particle size of 5.5 micrometers and pure silicon powder with a purity of 99.99% were selected. The mass ratio of tantalum powder to silicon powder was 9998:2. The mixture was mixed in a mixer for 60 minutes, then loaded into a latex-coated die and pressed into a billet in a cold isostatic press under a pressure of 210 MPa. The billet was then placed in a vacuum induction pre-sintering furnace and held at a high temperature of 1950℃ for 1.5 hours. After being removed from the furnace, it was placed in a vertical melting sintering furnace and held at a high temperature of 2550℃ for 2 hours. The tantalum billet after vertical melting sintering was rolled in multiple passes to obtain tantalum bars, with a rolling pass rate of 15%. The obtained tantalum bars were pickled, dried, and then placed in a vacuum induction annealing furnace at a set temperature of approximately 1400℃ and a vacuum degree maintained at 10. -3 The annealed tantalum strip is subjected to high-temperature vapor phase oxidation at 860℃, with oxygen introduced and held for 1.5 minutes. The oxidized tantalum strip is then drawn in a continuous wire drawing machine using liquid lubricant and tungsten steel wire drawing dies. The sizing zone is set at 15%, and a final tantalum wire product with a diameter of 0.29 mm is produced.

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

[0103] 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] The tantalum wire brittleness resistance test data were obtained by pressing capacitor-grade tantalum powder (20,000 specific capacitance) and tantalum wire (diameter: 0.29 mm) into an anode block using a molding process. The tantalum wire was buried in the anode block to a depth of approximately 1 / 3 of the anode block. The molded anode block was sintered at 1700℃, and then the tantalum wire exposed outside the anode block was subjected to a bending test until it broke. The number of bends is expressed as follows.

[0105]

[0106]

[0107] Comparative Example 4

[0108] Select a loose bulk density of 3.3 g / cm³. 3 Tantalum powder with an average particle size of 5.5 micrometers was selected. Pure yttrium and silicon powder, both with a purity of 99.99%, were used. The mass ratio of tantalum powder to yttrium powder and silicon powder was 9996:2:2. The mixture was stirred in a mixer for 30 minutes, then loaded into a latex-coated die and pressed into a billet in a cold isostatic press under a pressure of 210 MPa. The billet was then placed in a vacuum induction pre-sintering furnace, held at 1950℃ for 1.5 hours, and then transferred to a vertical melting sintering furnace, held at 2550℃ for 2 hours. The vertically melted tantalum billet was then rolled in multiple passes to obtain tantalum bars, with a rolling pass rate of 15%. The obtained tantalum bars were pickled, dried, and then placed in a vacuum induction annealing furnace at a temperature of approximately 1400℃, with the vacuum level maintained at 10. -3 The annealed tantalum strip is subjected to high-temperature vapor phase oxidation at 860℃, with oxygen introduced and held for 1.5 minutes. The oxidized tantalum strip is then drawn in a continuous wire drawing machine using liquid lubricant and tungsten steel wire drawing dies. The sizing zone is set at 15%. Based on different user specifications, a final tantalum wire product with a diameter of 0.4mm is produced.

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

[0110] 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] The tantalum wire brittleness resistance test data were obtained by pressing capacitor-grade tantalum powder (20,000 specific capacitance) and tantalum wire (diameter: 0.40 mm) into an anode block using a molding process. The tantalum wire was buried in the anode block to a depth of approximately 1 / 3 of the anode block. The molded anode block was sintered at 1700℃, and then the tantalum wire exposed outside the anode block was subjected to a bending test until it broke. The number of bends is expressed as follows.

[0112] 1 5 2 4 3 3 4 3 5 5 6 4 7 5 8 4 9 5 10 4

[0113] Typical grain size photographs of tantalum wires prepared from a direct mixture of yttrium powder and / or silicon powder and tantalum powder in Comparative Examples 2-4 under annealing conditions of 1700℃ / 60 minutes are shown below. Figure 2 As shown in the figure, the grain size is not uniform, indicating that the distribution of rare earth elements is uneven. This will lead to inconsistent tensile strength and inconsistent number of brittle wire bending times in tantalum wire.

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

[0115] Any feature disclosed in this specification, unless otherwise stated, may be replaced by other equivalent or similar features. Unless otherwise stated, each feature is merely one example of a series of equivalent or similar features.

[0116] Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which these exemplary embodiments pertain. The terminology used in this description is for descriptive purposes only and is not intended to limit the scope of the exemplary embodiments. Therefore, the overall inventive concept is not intended to be limited to the specific embodiments described herein. While preferred methods and materials are described herein, other methods and materials similar to or equivalent to those described herein may be used in the practice or testing of the invention.

[0117] Unless otherwise stated, all figures used in the specification and claims to represent amounts of components, chemical and molecular properties, reaction conditions, etc., should be understood to be modified by the term "about" in all cases. Therefore, unless indicated to the contrary, the numerical parameters set forth in the specification and appended claims are approximations that may vary depending on the desired properties sought to be obtained through the exemplary embodiments described herein. At least each numerical parameter should be interpreted according to the number of significant figures and common rounding methods.

[0118] While the numerical ranges and parameters described in the exemplary embodiments are approximate, the values ​​described in the specific embodiments are reported as precisely as possible. However, any numerical value inherently contains some error that is necessarily caused 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 falling within such a wider range, as such narrower numerical ranges are also expressly stated herein. Furthermore, any numerical values ​​reported in the embodiments may be used to define the upper or lower endpoints of the wider range of components disclosed herein.

Claims

1. A method for preparing tantalum wire with improved resistance to brittleness, the method comprising the following steps in sequence: (1) Mix 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 blank; (3) Sintering the master alloy blank; (4) Hydrogenating and powdering the sintered master alloy blank to obtain master alloy tantalum powder; (5) Mixing tantalum powder and one or more master alloy tantalum powders to form a second mixture; (6) Using the second mixture as a powder raw material to prepare tantalum wire.

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

5.

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

4. The method according to claim 1, wherein the sintering in step (3) is performed by holding at a high temperature holding point, which 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 master alloy billet after vertical melting and sintering is loaded into the hydrogenation furnace, the furnace temperature is set to 800-950°C, hydrogen is introduced, and the temperature is maintained.

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

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

8. The method according to claim 1, wherein after step (4) and before step (5), the method further comprises the following steps: loading the master alloy tantalum powder into a deoxidation furnace, loading magnesium powder, and keeping it warm; 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), tantalum powder and one or more master alloy tantalum powders are mixed such that the mass content of rare earth elements, 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) comprises the following sub-steps: (6-1) cold isostatic pressing the second mixture to obtain a tantalum billet; (6-2) sintering the tantalum billet by vertical melting; and (6-3) rolling and drawing the sintered tantalum billet.

12. A tantalum wire with improved resistance to brittleness, prepared by the method according to any one of claims 1 to 11.

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