A method of producing a pure iridium or platinum-iridium alloy strip
Patent Information
- Application Number
- CN202611303604.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-08-26
- Publication Date
- 2026-10-09
AI Technical Summary
然而，纯铱及高铱含量的铂铱合金属于极难加工的金属材料，其塑性加工过程极易出现开裂、分层等缺陷
1. 本发明通过粉末冶金工艺和热挤压工艺相结合，可减少合金成分偏差和粗大不均匀的铸态组织结构，从而实现组织细化、提升加工塑性。
Smart Images
Figure CN122875756A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of precious metal strip preparation technology, and relates to a method for preparing pure iridium or platinum-iridium alloy strip. Background Technology
[0002] Iridium possesses an extremely high melting point, excellent high-temperature strength, and outstanding corrosion resistance. Platinum-iridium alloys combine the excellent plasticity and chemical stability of platinum with the high hardness and wear resistance of iridium, thus exhibiting excellent resistance to arc erosion, good biocompatibility, and stable thermoelectric and electromagnetic properties. Therefore, pure iridium and platinum-iridium alloy strips play an irreplaceable role in modern high-tech fields: in aerospace, they are widely used in the manufacture of engine spark plug electrodes, high-temperature anti-oxidation coatings, and precision sensors; in biomedicine, due to their excellent biocompatibility and electrocatalytic activity, they serve as core materials for implantable medical devices such as pacemaker electrodes and nerve stimulation electrodes; in the chemical industry and electronics, they are used as high-specification catalytic meshes, precision sliding contacts, and elastic elements. Therefore, pure iridium and platinum-iridium alloy strips have significant research value and broad industrialization prospects.
[0003] Currently, the preparation methods for pure iridium and platinum-iridium alloy strips are mainly divided into two categories: powder metallurgy and smelting, followed by plastic deformation processes such as hot rolling, cold rolling, and annealing. However, pure iridium and high-iridium-content platinum-iridium alloys are extremely difficult-to-process metallic materials, and their plastic processing is prone to defects such as cracking and delamination. In particular, the coarse grains in the as-cast structure after smelting make it very easy for cracks to occur along the grain boundaries during the initial hot rolling process; and the sintered billet inevitably contains residual micropores, which can become crack initiation points during the hot rolling process, leading to strip delamination or even fracture.
[0004] Therefore, it is necessary to provide a method for preparing pure iridium or platinum-iridium alloy strips to solve the bottleneck problems that are common in the current preparation process of pure iridium and platinum-iridium alloy strips, such as low yield, high processing difficulty, long processing cycle and high cost. It is also necessary to develop a method that can effectively control grain size, improve yield and shorten processing cycle, so as to achieve high yield of iridium-based strip production. Summary of the Invention
[0005] To overcome the problems in the prior art, this invention combines powder metallurgy and hot extrusion processes to refine the grain size of pure iridium and platinum-iridium alloys, thereby improving the processing plasticity and overall performance of pure iridium or platinum-iridium alloys. Compared with traditional smelting processes, the pure iridium and platinum-iridium alloy strips prepared by the method of this invention have a uniform microstructure and fine grains, which is beneficial for subsequent large plastic deformation processing into pure iridium or platinum-iridium alloy strips.
[0006] To achieve the above objectives, the present invention is implemented through the following technical solution: This invention proposes a method for preparing pure iridium or platinum-iridium alloy strips, the method comprising the following steps: (1) The raw material powder is mixed by vacuum ball milling to obtain mixed powder.
[0007] (2) The mixed powder in step (1) is subjected to reduction treatment to reduce the oxygen content in the mixed powder.
[0008] (3) The mixed powder with reduced oxygen content in step (2) is subjected to vacuum hot pressing sintering and hot extrusion integrated treatment to obtain strip blank.
[0009] (4) The strip blank in step (3) is subjected to cold rolling-annealing cyclic plastic processing to obtain pure iridium or platinum-iridium alloy strip.
[0010] When preparing pure iridium strips, pure iridium powder is used as the raw material powder; when preparing platinum-iridium alloy strips, pure iridium powder and pure platinum powder are used as the raw material powder.
[0011] Preferably, in step (1), the ball milling speed is 200~400 r / min, the ball-to-material ratio is 5:1~10:1, and the ball milling time is 6~12 h.
[0012] Preferably, in step (2), the reduction treatment temperature is 300~500℃ and the reduction treatment time is 1~4h.
[0013] The mixed powder is subjected to reduction treatment using a reducing atmosphere, wherein the reducing atmosphere is an argon-hydrogen mixture, in which hydrogen accounts for 10% by volume and the remainder is argon.
[0014] Preferably, in step (3), the hot pressing sintering temperature is 1200~1400℃, the heat holding and pressure holding time is 1~4h, and the sintering pressure is 50MPa.
[0015] Preferably, the heating rate in step (3) is 10℃ / min.
[0016] Preferably, in step (3), the hot extrusion pressure is 50 tons and the hot extrusion deformation is 50%.
[0017] Preferably, in step (4), cyclic plastic processing is performed by annealing after every two cold rolling cycles.
[0018] The cyclic plastic processing method of annealing after every two cold rolling cycles helps to reduce the frequency of processing changes while ensuring excellent strip performance, thereby improving strip production efficiency.
[0019] Preferably, in step (4), the deformation amount per cold rolling pass is 1% to 2%, and the total deformation amount is 60% to 94%.
[0020] Preferably, in step (4), the annealing temperature is 400~800℃ and the holding time is 2~6h each time.
[0021] Preferably, in step (1), the purity of the raw material powder is ≥99.9%, and the particle size of the raw material powder is 10~30μm.
[0022] Preferably, in step (1), the vacuum degree is <20 Pa.
[0023] Preferably, in step (3), the vacuum degree is less than 10. -3 Pa.
[0024] The beneficial effects of this invention are: 1. This invention combines powder metallurgy and hot extrusion processes to reduce alloy composition deviations and coarse, uneven as-cast microstructures, thereby achieving microstructure refinement and improved processing plasticity.
[0025] 2. This invention uses an integrated hot sintering and hot extrusion equipment to perform integrated hot pressing and hot extrusion processing, avoiding material loss and reducing energy consumption in subsequent processing, thereby reducing the processing cost of pure iridium or platinum-iridium alloy strips and laying a good foundation for the consistency of subsequent processing.
[0026] 3. This invention employs a "cold rolling-annealing" cyclic plastic processing technology to avoid abnormal grain growth during prolonged and repeated hot rolling, which would significantly increase the brittleness of pure iridium or iridium-platinum alloy materials, thereby reducing the difficulty of material rolling and improving the yield. Attached Figure Description
[0027] Figure 1 This is a schematic diagram of the preparation process of the present invention; Figure 2 EBSD image of pure iridium tape prepared for comparison; Figure 3 This is an EBSD image of the pure iridium tape prepared in Example 1 of the present invention. Detailed Implementation
[0028] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments, but the scope of protection of the present invention is not limited to the content described.
[0029] Example 1 In this embodiment, pure iridium tape is prepared by the following method: (1) Pure iridium powder with a purity of ≥99.9% and a particle size of 10~30μm was added to a polytetrafluoroethylene ball milling jar for vacuum ball milling and mixing to reduce the phenomenon of pure iridium agglomeration during the chemical preparation process. After vacuum ball milling and mixing, a mixed powder was obtained. The vacuum ball milling speed was 200r / min, the ball milling time was 12 hours, the ball-to-material ratio was 5:1, and the vacuum degree was 19Pa.
[0030] (2) Place the mixed powder in a tube furnace, introduce an argon-hydrogen mixture with a hydrogen volume percentage of 10% into the tube furnace, and heat the mixed powder to 300°C for 4 hours to reduce the oxygen content in the mixed powder.
[0031] (3) A vacuum hot pressing and hot extrusion integrated equipment is used to perform vacuum hot pressing and hot extrusion integrated treatment on low oxygen content mixed powder, with a vacuum degree of 10. -4 The heating rate was 10℃ / min, the sintering temperature was 1200℃, the sintering pressure was 50MPa, and the holding time was 4h. The sintered billet was then directly hot-extruded under a pressure of 50 tons, and the deformation was controlled at 50% to obtain a strip billet with a thickness of 5.0mm.
[0032] (4) The strip billet is subjected to "cold rolling-annealing" cyclic plastic processing in accordance with the method of annealing after each cold rolling twice. The deformation amount of a single cold rolling pass is controlled at 1%, the total deformation amount is 70%, the annealing temperature is 600℃, and the holding time for each annealing is 2h. After cyclic plastic processing, a pure iridium strip with a thickness of 1.5mm is obtained.
[0033] Example 2 In this embodiment, pure iridium tape is prepared by the following method: (1) Pure iridium powder with a purity of ≥99.9% and a particle size of 10~30μm was added to a polytetrafluoroethylene ball milling jar for vacuum ball milling and mixing to reduce the phenomenon of pure iridium agglomeration during the chemical preparation process. After vacuum ball milling and mixing, a mixed powder was obtained. The vacuum ball milling speed was 400r / min, the ball milling time was 6 hours, the ball-to-material ratio was 10:1, and the vacuum degree was 18Pa.
[0034] (2) Place the mixed powder in a tube furnace, introduce an argon-hydrogen mixture with a hydrogen volume percentage of 10% into the tube furnace, and heat the mixed powder to 500°C for 2 hours to reduce the oxygen content in the mixed powder.
[0035] (3) A vacuum hot pressing and hot extrusion integrated equipment is used to perform vacuum hot pressing and hot extrusion integrated treatment on low oxygen content mixed powder, with a vacuum degree of 10. -5The heating rate was 10℃ / min, the sintering temperature was 1400℃, the sintering pressure was 50MPa, and the holding time was 2h. The sintered billet was then directly hot-extruded under a pressure of 50 tons, and the deformation was controlled at 50% to obtain a strip billet with a thickness of 5.0mm.
[0036] (4) The strip billet is subjected to "cold rolling-annealing" cyclic plastic processing in accordance with the method of annealing after each cold rolling twice. The deformation amount of a single cold rolling pass is controlled at 2%, the total deformation amount is 94%, the annealing temperature is 800℃, and the holding time for each annealing is 4h. After cyclic plastic processing, a pure iridium strip with a thickness of 0.3mm is obtained.
[0037] Example 3 This embodiment uses the following method to prepare platinum-iridium alloy strip: (1) Pure iridium and pure platinum powder with a purity of ≥99.9% and a particle size of 10~30μm (the mass ratio of pure iridium to pure platinum is iridium:platinum=1:9) are added to a polytetrafluoroethylene ball milling jar for vacuum ball milling to reduce the phenomenon of pure iridium agglomeration during the chemical preparation process. After vacuum ball milling, a mixed powder is obtained. The vacuum ball milling speed is 400r / min, the ball milling time is 6 hours, the ball-to-material ratio is 10:1, and the vacuum degree is 18Pa.
[0038] (2) Place the mixed powder in a tube furnace, introduce an argon-hydrogen mixture with a hydrogen volume percentage of 10% into the tube furnace, and heat the mixed powder to 500°C for 2 hours to reduce the oxygen content in the mixed powder.
[0039] (3) A vacuum hot pressing and hot extrusion integrated equipment is used to perform vacuum hot pressing and hot extrusion integrated treatment on low oxygen content mixed powder, with a vacuum degree of 10. -4 The heating rate was 10℃ / min, the sintering temperature was 1300℃, the sintering pressure was 50MPa, and the holding time was 1h. The sintered billet was then directly hot-extruded under a pressure of 50 tons, and the deformation was controlled at 50% to obtain a strip billet with a thickness of 5.0mm.
[0040] (4) The strip billet is subjected to "cold rolling-annealing" cyclic plastic processing in accordance with the method of annealing after each cold rolling twice. The deformation amount of a single cold rolling pass is controlled at 1.5%, the total deformation amount is 60%, the annealing temperature is 800℃, and the holding time for each annealing is 6h. After cyclic plastic processing, a platinum-iridium alloy strip with a thickness of 2.0mm is obtained.
[0041] Example 4 This embodiment uses the following method to prepare platinum-iridium alloy strip: (1) Pure iridium and pure platinum powder with a purity ≥99.9% and a particle size of 10~30μm (the mass ratio of pure iridium to pure platinum is iridium:platinum=3:7) are added to a polytetrafluoroethylene ball milling jar for vacuum ball milling to reduce the phenomenon of pure iridium agglomeration during the chemical preparation process. After vacuum ball milling, a mixed powder is obtained. The vacuum ball milling speed is 300r / min, the ball milling time is 10 hours, the ball-to-material ratio is 8:1, and the vacuum degree is 15Pa.
[0042] (2) Place the mixed powder in a tube furnace, introduce an argon-hydrogen mixture with a hydrogen volume percentage of 10% into the tube furnace, and heat the mixed powder to 400°C for 1 hour to reduce the oxygen content in the mixed powder.
[0043] (3) A vacuum hot pressing and hot extrusion integrated equipment is used to perform vacuum hot pressing and hot extrusion integrated treatment on low oxygen content mixed powder, with a vacuum degree of 10. -4 The heating rate was 10℃ / min, the sintering temperature was 1200℃, the sintering pressure was 50MPa, and the holding time was 4h. The sintered billet was then directly hot-extruded under a pressure of 50 tons, and the deformation was controlled at 50% to obtain a strip billet with a thickness of 5.0mm.
[0044] (4) The strip billet is subjected to "cold rolling-annealing" cyclic plastic processing in accordance with the method of annealing after each cold rolling twice. The deformation amount of a single cold rolling pass is controlled at 1%, the total deformation amount is 80%, the annealing temperature is 400℃, and the holding time for each annealing is 6h. After cyclic plastic processing, a platinum-iridium alloy strip with a thickness of 1.0mm is obtained.
[0045] Comparative Example This comparative example uses the same method as Example 1 to prepare pure iridium strip, except that the ball milling, hot pressing sintering, and hot extrusion processes are replaced with melting. First, the pure iridium powder is cold-pressed into a block, then melted and cast into an ingot, and then the ingot is subjected to a "cold rolling + annealing" cycle of plastic processing. The final thickness of the pure iridium strip is 1.5 mm.
[0046] The pure iridium or platinum-iridium tapes prepared in Examples 1-4 of this invention do not exhibit defects such as breakage or delamination, have similar performance, and show good quality stability.
[0047] pass Figure 2 and Figure 3The comparison shows that the pure iridium strip prepared by replacing the melting method with the powder metallurgy + hot pressing sintering and hot extrusion integrated processing process of the present invention has a finer grain size and better grain orientation consistency, with no obvious grain orientation difference. Therefore, when the crystal plane (101) of the pure iridium strip prepared by the present invention is aligned, the movement of the internal slip system of the iridium strip crystal becomes more coordinated, so that the iridium strip can withstand a greater amount of deformation without cracking during subsequent cold rolling or bending.
[0048] In summary, this invention, through systematic optimization of the preparation method of iridium-based strip, can achieve the goal of refining the grain size of the strip, thereby improving the alloy's processing plasticity and overall performance, increasing production efficiency, and reducing processing costs.
[0049] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.
Claims
1. A method for preparing pure iridium or platinum-iridium alloy strip, characterized in that: The preparation method includes the following steps: (1) The raw material powder is mixed by vacuum ball milling to obtain a mixed powder; (2) The mixed powder in step (1) is subjected to reduction treatment to reduce the oxygen content in the mixed powder; (3) The mixed powder with reduced oxygen content in step (2) is subjected to vacuum hot pressing sintering and hot extrusion integrated treatment to obtain strip blank; (4) The strip blank in step (3) is subjected to cold rolling-annealing cyclic plastic processing to obtain pure iridium or platinum-iridium alloy strip.
2. The preparation method according to claim 1, characterized in that: In step (1), the ball milling speed is 200~400 r / min, the ball-to-material ratio is 5:1~10:1, and the ball milling time is 6~12 h.
3. The preparation method according to claim 1, characterized in that: In step (2), the reduction treatment temperature is 300~500℃ and the reduction treatment time is 1~4h; The mixed powder is subjected to reduction treatment using a reducing atmosphere, wherein the reducing atmosphere is an argon-hydrogen mixture, in which hydrogen accounts for 10% by volume and the remainder is argon.
4. The preparation method according to claim 1, characterized in that: In step (3), the hot pressing sintering temperature is 1200~1400℃, the heat holding and pressure holding time is 1~4h, and the sintering pressure is 50MPa.
5. The preparation method according to claim 1, characterized in that: In step (3), the hot extrusion pressure is 50 tons and the hot extrusion deformation is 50%.
6. The preparation method according to claim 1, characterized in that: In step (4), cyclic plastic processing is performed by annealing after every two cold rolling cycles.
7. The preparation method according to claim 1 or 6, characterized in that: In step (4), the deformation amount of a single cold rolling pass is 1% to 2%, and the total deformation amount is 60% to 94%.
8. The preparation method according to claim 1 or 6, characterized in that: In step (4), the annealing temperature is 400~800℃, and the holding time is 2~6h each time.
9. The preparation method according to any one of claims 1-6, characterized in that: In step (1), the purity of the raw material powder is ≥99.9%, and the particle size of the raw material powder is 10~30μm.