Preparation method of niobium and niobium alloy capillary tube

Abstract

The invention discloses a preparation method of a niobium and niobium alloy capillary tube, which comprises the following steps of: 1, filling high-purity argon into an inner hole of a seamless tube, and sealing two ends by argon arc welding; 2, performing surface oxidation on the pipe by adopting an electromagnetic induction constant-temperature oxidation device to obtain a pipe to be cold-drawn; 3, cold drawing to obtain a capillary tube; and 4, cleaning the outer surface of the capillary tube, cutting off the sealing head, carrying out finished product heat treatment, and straightening to obtain a finished tube. According to the method, the inner hole of the pipe is filled with argon, the two ends of the pipe are welded and sealed, an existing surface oxidation technology is changed, only the outer surface of the drawn pipe is oxidized, and the inner hole can be prevented from being oxidized during surface oxidation; meanwhile, the trouble brought to later cleaning due to the fact that oil stains pollute the inner hole in the cold drawing process can be avoided; the electromagnetic induction constant-temperature oxidation device is adopted, the thickness of an oxidation layer is very uniform, the yield can reach 100% in the later cold drawing process, and the yield is increased.

Description

Technical Field

[0001] The invention belongs to the technical field of metal material processing, and in particular relates to a method for preparing a niobium and niobium alloy capillary. Background Art

[0002] Niobium and niobium alloys have the characteristics of high melting point, good low-temperature plasticity, good biocompatibility, and relatively abundant resources. Niobium and niobium alloy capillaries can be used in precision instruments in the medical field, aviation field, aerospace field, etc. The capillary is a very fine product, with an outer diameter usually less than 3mm, a wall thickness usually between 0.1 and 1mm, an inner diameter usually not exceeding 1mm, and a very light weight. Correspondingly, there are high requirements for the outer diameter, wall thickness, ellipticity, inner hole cleanliness, and surface finish of the capillary. The surface area of ​​the capillary is large and easily contaminated, and the surface of the niobium and niobium alloy capillary is easily oxidized due to heat during processing.

[0003] Compared with pure niobium, the processing performance of niobium alloy will gradually become difficult with the increase of the content of added elements, and the processing rate will gradually decrease. The existing processing methods of niobium and niobium alloy capillary niobium tubes are as follows: the tube blank is prepared by machining or extrusion in the early stage, and the tube blank is rolled into a tube of suitable specifications by cold rolling, and then processed into a finished tube by hot drawing or cold drawing in the later stage. During the cold drawing process, the capillary niobium tube needs to be coated with an oxide layer on the surface. Without the oxide layer as lubrication, the cold drawing process is difficult to proceed normally, or many surface defects will be caused on the surface, resulting in the product being unable to meet the requirements of use. The surface oxidation of the niobium tube can usually be carried out by muffle furnace atmospheric oxidation, anodic oxidation and other methods. During the surface atmospheric oxidation, not only an oxide film will be generated on the outer surface, but also an oxide film will be generated on the inner surface (but we do not want the inner hole to be oxidized). At the same time, the surface oxide layer is very uneven during the atmospheric oxidation of the muffle furnace. In the later drawing process, it is easy to cause adhesion of the mold, resulting in mold damage and scrapping and reduced yield rate. In the drawing process, the lubricating oil will enter the interior of the tube through the capillary effect, which will cause great trouble for the later cleaning of the inner hole. The hot working process itself will cause oxidation of the inner and outer surfaces at the same time. When removing oil stains and pickling the oxide layer of the finished capillary after drawing, the oil stains are usually difficult to clean because the inner hole is very small (the inner hole is usually less than 1mm). When pickling to remove the oxide layer, not only will the oxide scale be removed by pickling, but it will also cause corrosion of the base niobium material, resulting in thinning of the wall thickness. The wall thickness is not well controlled, which is not conducive to controlling the wall thickness tolerance (the wall thickness tolerance requires ±0.01mm). When anodizing is used, there will also be problems with inner hole oxidation and cleaning. At the same time, the non-destructive anodizing method is not friendly to the environment and personnel health. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a method for preparing niobium and niobium alloy capillaries in view of the shortcomings of the above-mentioned prior art. The method fills the inner hole of the tube with argon gas and seals the two ends by welding, which changes the existing surface oxidation technology and only oxidizes the outer surface of the drawn tube, thereby avoiding oxidation of the inner hole during surface oxidation; at the same time, it can avoid the trouble of oil pollution of the inner hole during the cold drawing process, which causes trouble for later cleaning; the electromagnetic induction constant temperature oxidation device is used, and the thickness of the oxide layer is very uniform, and the finished product rate can reach 100% in the later cold drawing process, thereby improving the yield rate.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is: a method for preparing niobium and niobium alloy capillaries, characterized in that it comprises the following steps:

[0006] Step 1, filling the inner hole of the seamless pipe with high purity argon gas, and sealing the two ends with argon arc welding; the seamless pipe is a niobium pipe or a niobium alloy pipe;

[0007] Step 2: using an electromagnetic induction constant temperature oxidation device to perform surface oxidation on the tube sealed by filling argon in step 1 to obtain a tube to be cold drawn; the electromagnetic induction constant temperature oxidation device comprises a quartz glass tube and an induction coil wound on the quartz glass tube, a first end plug is provided at the inlet of the quartz glass tube, a second end plug is provided at the outlet of the quartz glass tube, a through hole for the tube to pass through is provided at the center of the first end plug and the second end plug, a temperature measuring port and a vent are provided on the first end plug, an air outlet is provided on the second end plug, and a temperature sensor is provided in the temperature measuring port;

[0008] Step 3, cold drawing the tube to be cold drawn in step 2 to obtain a capillary tube;

[0009] Step 4: Clean the outer surface of the capillary tube formed by cold drawing in step 3, cut off the sealing head, perform heat treatment on the finished product and straighten it to obtain a finished tube.

[0010] The above-mentioned method for preparing a niobium and niobium alloy capillary is characterized in that the surface oxidation process in step 2 includes: introducing compressed air into the quartz glass tube through the vent, adjusting the output power of the induction coil until the temperature detected by the temperature sensor reaches the required heating temperature, and passing the tube sealed with argon gas through the quartz glass tube at a uniform speed to form an oxide coating on the surface of the tube.

[0011] The above-mentioned method for preparing niobium and niobium alloy capillaries is characterized in that the effective residence time of each part of the tube in the quartz glass tube is 8s to 25s.

[0012] The above-mentioned method for preparing niobium and niobium alloy capillaries is characterized in that the cleaning in step 4 includes metal cleaning agent cleaning and pickling, and the pickling adopts a mixed acid of dilute nitric acid and hydrofluoric acid, and the volume percentage of HNO3 in the mixed acid is 10% to 15%, and the volume percentage of HF is 1% to 2%.

[0013] The above-mentioned method for preparing niobium and niobium alloy capillaries is characterized in that the temperature of the heat treatment of the finished product in step 4 is 900° C. to 1250° C., and the insulation time is 60 min to 240 min.

[0014] Compared with the prior art, the present invention has the following advantages:

[0015] 1. The present invention fills the inner hole of the pipe with argon gas and welds the two ends to seal, which changes the existing surface oxidation technology. Only the outer surface of the drawn pipe is oxidized, which can avoid oxidation of the inner hole during surface oxidation; at the same time, it can avoid oil pollution of the inner hole during the cold drawing process (especially avoiding the inner hole being filled with lubricating oil due to the capillary effect) to cause trouble for later cleaning. Because the difficulty of cleaning often limits the length of the finished pipe to be not too long.

[0016] 2. The present invention adopts an electromagnetic induction constant temperature oxidation device to uniformly heat the pipe through the induction coil at a uniform speed for surface oxidation. During the oxidation process, air enters from the vent and is discharged from the outlet. The heating power can be adjusted according to the temperature detected by the temperature sensor, which can ensure that the surface of the pipe can be oxidized very evenly during the oxidation process, avoiding the problem of sticking to the mold in the later cold drawing process due to uneven oxidation layer caused by uneven local oxidation during chemical oxidation or atmospheric atmosphere muffle furnace oxidation, which affects the yield rate. The thickness of the oxide layer is very uniform when using this method, and the yield rate can reach 100% in the later cold drawing process, which improves the yield rate.

[0017] The technical solution of the present invention is further described in detail below in conjunction with embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a schematic diagram of the structure in which the inner hole of the seamless pipe of the present invention is filled with argon and both ends are sealed.

[0019] Figure 2 This is a physical picture of the seamless pipe after sealing according to the present invention.

[0020] Figure 3 It is a schematic structural diagram of the electromagnetic induction constant temperature oxidation device of the present invention.

[0021] Figure 4 This is a direct view of the outer and inner surfaces of the finished capillary niobium tube prepared by the present invention.

[0022] Description of reference numerals:

[0023] 1—quartz glass tube; 2—induction coil; 3—first end plug;

[0024] 4—Second end plug; 5—Pipe; 6—Temperature measuring port;

[0025] 7—Ventilation port; 8—Air outlet; 9—Temperature sensor. DETAILED DESCRIPTION

[0026] like Figure 1 As shown, the electromagnetic induction constant temperature oxidation device used in the following embodiments includes a quartz glass tube 1 and an induction coil 2 wound on the quartz glass tube 1, a first end plug 3 is provided at the inlet of the quartz glass tube 1, and a second end plug 4 is provided at the outlet of the quartz glass tube 1, and the centers of the first end plug 3 and the second end plug 4 are both provided with through holes for the pipe 5 to pass through, the first end plug 3 is provided with a temperature measuring port 6 and a vent 7, the second end plug 4 is provided with an outlet 8, and a temperature sensor 9 is provided in the temperature measuring port 6.

[0027] Example 1

[0028] Select seamless niobium tubes with specifications of Φ3.5×0.5×1000 (mm) as raw materials for processing capillary niobium tubes;

[0029] Step 1: Fill the inner hole of the seamless niobium tube with a size of Φ3.5×0.5×1000 (mm) with high-purity argon gas, and seal the two ends with argon arc welding. Figure 1 and Figure 2 As shown;

[0030] The specific process is as follows: high-purity argon gas is introduced into the niobium tube from one end, and the gas flow is adjusted to 5L / min. After the argon gas is continuously introduced for 20 seconds, the gas flow is adjusted to 0L / min. Then, one end of the niobium tube is immediately sealed by argon arc welding. After sealing, the argon gas is removed, and the other end is sealed by argon arc welding at the same time.

[0031] Step 2: using an electromagnetic induction constant temperature oxidation device to perform surface oxidation on the niobium tube sealed with argon gas in step 1 to obtain a tube to be cold drawn;

[0032] The specific process is as follows: compressed air is introduced into the quartz glass tube 1 through the vent 7, the compressed air flow is adjusted to 10L / min, the output power of the induction coil 2 is adjusted until the temperature detected by the temperature sensor 9 reaches the required heating temperature of 650°C, the niobium tube sealed with argon in step 1 is passed through the quartz glass tube 1 at a uniform speed of 10mm / s, the effective heating length of the induction coil 2 is 200mm, the effective residence time of the niobium tube is 20s, and an oxide coating is formed on the surface of the niobium tube;

[0033] Step 3, cold drawing the tube to be cold drawn in step 2 to obtain a capillary niobium tube;

[0034] The specific process is as follows: one end of the tube to be cold drawn in step 2 is rolled on a rolling machine to facilitate passing through the cold drawing die, and the niobium tube with a specification of Φ3.5×0.5×L (mm) is cold drawn into a finished capillary niobium tube with a specification of Φ2.0×0.5×L (mm);

[0035] Step 4: Clean the outer surface of the capillary niobium tube in step 3 with a metal cleaning agent and pickle. The metal cleaning agent is a conventional metal cleaning agent. The pickling adopts a mixed acid of dilute nitric acid and hydrofluoric acid. The volume percentage of HNO3 in the mixed acid is 15%, and the volume percentage of HF is 1%. After cutting off the sealing head, the finished product is heat treated and straightened to obtain a finished tube with a finished product rate of 100%; the temperature of the finished product heat treatment is 900°C, and the insulation time is 180min.

[0036] Example 2

[0037] Select seamless niobium tubes with specifications of Φ3.5×0.2×1000 (mm) as raw materials for processing capillary niobium tubes;

[0038] Step 1: Fill the inner hole of the seamless niobium tube with a size of Φ3.5×0.2×1000 (mm) with high-purity argon gas, and seal the two ends with argon arc welding. Figure 1 and Figure 2 As shown;

[0039] The specific process is as follows: high-purity argon gas is introduced into the niobium tube from one end, and the gas flow is adjusted to 5L / min. After the argon gas is continuously introduced for 20 seconds, the gas flow is adjusted to 0L / min. Then, one end of the niobium tube is immediately sealed by argon arc welding. After sealing, the argon gas is removed, and the other end is sealed by argon arc welding at the same time.

[0040] Step 2: using an electromagnetic induction constant temperature oxidation device to perform surface oxidation on the niobium tube sealed with argon gas in step 1 to obtain a tube to be cold drawn;

[0041] The specific process is as follows: compressed air is introduced into the quartz glass tube 1 through the vent 7, the compressed air flow is adjusted to 10 L / min, the output power of the induction coil 2 is adjusted until the temperature detected by the temperature sensor 9 reaches the required heating temperature of 700°C, the niobium tube sealed with argon in step 1 is passed through the quartz glass tube 1 at a uniform speed of 25 mm / s, the effective heating length of the induction coil 2 is 200 mm, the effective residence time of the niobium tube is 8 s, and an oxide coating is formed on the surface of the niobium tube;

[0042] Step 3, cold drawing the tube to be cold drawn in step 2 to obtain a capillary niobium tube;

[0043] The specific process is as follows: one end of the tube to be cold drawn in step 2 is rolled on a rolling machine to facilitate passing through the cold drawing die, and the niobium tube with a specification of Φ3.5×0.2×L (mm) is cold drawn into a finished capillary niobium tube with a specification of Φ1.7×0.2×L (mm);

[0044] Step 4: Clean the outer surface of the capillary niobium tube in step 3 with a metal cleaning agent and pickle. The metal cleaning agent is a conventional metal cleaning agent. The pickling adopts a mixed acid of dilute nitric acid and hydrofluoric acid. The volume percentage of HNO3 in the mixed acid is 10%, and the volume percentage of HF is 2%. After cutting off the sealing head, the finished product is heat treated and straightened to obtain a finished tube with a finished product rate of 100%; the temperature of the finished product heat treatment is 1100°C, and the insulation time is 60min.

[0045] Example 3

[0046] A seamless niobium-zirconium alloy tube with a specification of Φ3.5×0.25×1000 (mm) is selected as the raw material for processing the capillary niobium tube;

[0047] Step 1: Fill the inner hole of a seamless niobium-zirconium alloy tube with a size of Φ3.5×0.25×1000 (mm) with high-purity argon gas, and seal both ends with argon arc welding. Figure 1 and Figure 2 As shown;

[0048] The specific process is as follows: high-purity argon gas is introduced into the niobium-zirconium alloy tube from one end, and the gas flow is adjusted to 5L / min. After the argon gas is continuously introduced for 20 seconds, the gas flow is adjusted to 0L / min. Then, one end of the niobium-zirconium alloy tube is immediately sealed by argon arc welding. After sealing, the argon gas is removed, and the other end is sealed by argon arc welding.

[0049] Step 2: using an electromagnetic induction constant temperature oxidation device to perform surface oxidation on the niobium-zirconium alloy tube sealed with argon gas in step 1, to obtain a tube to be cold drawn;

[0050] The specific process is as follows: compressed air is introduced into the quartz glass tube 1 through the vent 7, the compressed air flow is adjusted to 10L / min, the output power of the induction coil 2 is adjusted until the temperature detected by the temperature sensor 9 reaches the required heating temperature of 650°C, the niobium-zirconium alloy tube sealed with argon in step 1 is passed through the quartz glass tube 1 at a uniform speed of 20mm / s, the effective heating length of the induction coil 2 is 200mm, the effective residence time of the niobium-zirconium alloy tube is 10s, and an oxide coating is formed on the surface of the niobium-zirconium alloy tube;

[0051] Step 3, cold drawing the tube to be cold drawn in step 2 to obtain a capillary niobium-zirconium alloy tube;

[0052] The specific process is as follows: one end of the tube to be cold drawn in step 2 is rolled on a rolling machine to facilitate passing through the cold drawing die, and the niobium-zirconium alloy tube with a specification of Φ3.5×0.25×L (mm) is cold drawn into a finished capillary niobium-zirconium alloy tube with a specification of Φ1.6×0.25×L (mm);

[0053] Step 4: Clean and pickle the outer surface of the capillary niobium-zirconium alloy tube in step 3 with a metal cleaning agent. The metal cleaning agent is a conventional metal cleaning agent. The pickling adopts a mixed acid of dilute nitric acid and hydrofluoric acid. The volume percentage of HNO3 in the mixed acid is 12%, and the volume percentage of HF is 1.5%. After cutting off the sealing head, the finished product is heat treated and straightened to obtain a finished tube with a finished product rate of 100%; the temperature of the heat treatment of the finished product is 1250°C, and the insulation time is 60min.

[0054] Example 4

[0055] A seamless niobium-tantalum-hafnium alloy tube with a specification of Φ3.5×0.65×1000 (mm) is selected as the raw material for processing the capillary niobium tube;

[0056] Step 1: Fill the inner hole of a seamless niobium-tantalum-hafnium alloy tube with a size of Φ3.5×0.65×1000 (mm) with high-purity argon gas, and seal both ends with argon arc welding. Figure 1 and Figure 2 As shown;

[0057] The specific process is as follows: high-purity argon gas is introduced into the niobium-tantalum-hafnium alloy tube from one end, and the gas flow is adjusted to 5L / min. After the argon gas is continuously introduced for 20 seconds, the gas flow is adjusted to 0L / min. Then, one end of the niobium-tantalum-hafnium alloy tube is immediately sealed by argon arc welding. After sealing, the argon gas is removed, and the other end is sealed by argon arc welding at the same time.

[0058] Step 2: using an electromagnetic induction constant temperature oxidation device to perform surface oxidation on the niobium, tantalum and hafnium alloy tube sealed with argon gas in step 1 to obtain a tube to be cold drawn;

[0059] The specific process is as follows: compressed air is introduced into the quartz glass tube 1 through the vent 7, the compressed air flow is adjusted to 10 L / min, the output power of the induction coil 2 is adjusted until the temperature detected by the temperature sensor 9 reaches the required heating temperature of 650°C, the niobium tantalum hafnium alloy tube sealed with argon in step 1 is passed through the quartz glass tube 1 at a uniform speed of 8 mm / s, the effective heating length of the induction coil 2 is 200 mm, the effective residence time of the niobium tantalum hafnium alloy tube is 25 s, and an oxide coating is formed on the surface of the niobium tantalum hafnium alloy tube;

[0060] Step 3, cold drawing the tube to be cold drawn in step 2 to obtain a capillary niobium tantalum hafnium alloy tube;

[0061] The specific process is as follows: one end of the tube to be cold drawn in step 2 is rolled on a rolling machine to facilitate passing through the cold drawing die, and the niobium-tantalum-hafnium alloy tube with a specification of Φ3.5×0.65×L(mm) is cold drawn into a finished capillary niobium-tantalum-hafnium alloy tube with a specification of Φ2.0×0.65×L(mm);

[0062] Step 4: Clean the outer surface of the capillary niobium tantalum hafnium alloy tube in step 3 with a metal cleaning agent and pickling. The metal cleaning agent is a conventional metal cleaning agent. The pickling adopts a mixed acid of dilute nitric acid and hydrofluoric acid. The volume percentage of HNO3 in the mixed acid is 10%, and the volume percentage of HF is 2%. After cutting off the sealing head, the finished product is heat treated and straightened to obtain a finished tube with a finished product rate of 100%; the temperature of the finished product heat treatment is 1180°C, and the insulation time is 240min.

[0063] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent structural change made to the above embodiment according to the technical essence of the invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. A method for preparing niobium and niobium alloy capillaries, characterized in that: The following steps are involved: Step 1, filling the inner hole of the seamless pipe with high purity argon gas, and sealing the two ends with argon arc welding; the seamless pipe is a niobium pipe or a niobium alloy pipe; Step 2: Using an electromagnetic induction constant temperature oxidation device to oxidize the surface of the tube sealed by filling with argon gas in step 1, so as to obtain a tube to be cold drawn; the electromagnetic induction constant temperature oxidation device comprises a quartz glass tube (1) and an induction coil (2) wound on the quartz glass tube (1); a first end plug (3) is arranged at the inlet of the quartz glass tube (1); a second end plug (4) is arranged at the outlet of the quartz glass tube (1); a through hole for the tube (5) to pass through is arranged at the center of the first end plug (3) and the second end plug (4); a temperature measuring port (6) and a vent (7) are provided on the first end plug (3); an air outlet (8) is provided on the second end plug (4); a temperature sensor (9) is arranged in the temperature measuring port (6); Step 3, cold drawing the tube to be cold drawn in step 2 to obtain a capillary tube; Step 4: Clean the outer surface of the capillary tube formed by cold drawing in step 3, cut off the sealing head, perform heat treatment on the finished product and straighten it to obtain a finished tube.

2. The method for preparing a niobium and niobium alloy capillary according to claim 1, characterized in that: The surface oxidation process in step 2 comprises: introducing compressed air into the quartz glass tube (1) through the vent (7), adjusting the output power of the induction coil (2) until the temperature detected by the temperature sensor (9) reaches the required heating temperature, and passing the argon-filled and sealed tube (5) through the quartz glass tube (1) at a uniform speed to form an oxide coating on the surface of the tube.

3. The method for preparing a niobium and niobium alloy capillary according to claim 2, characterized in that: The effective residence time of each part of the tube (5) in the quartz glass tube (1) is 8s to 25s.

4. The method for preparing a niobium and niobium alloy capillary according to claim 1, characterized in that: The cleaning in step 4 includes cleaning with a metal cleaning agent and pickling, wherein the pickling uses a mixed acid of dilute nitric acid and hydrofluoric acid, wherein the volume percentage of HNO3 in the mixed acid is 10% to 15%, and the volume percentage of HF is 1% to 2%.

5. The method for preparing a niobium and niobium alloy capillary according to claim 1, characterized in that: The temperature of the finished product heat treatment in step 4 is 900°C to 1250°C, and the insulation time is 60min to 240min.

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