A method of controlling segregation in platinum-rhodium alloys

Abstract

The application provides a method for controlling segregation of platinum-rhodium alloy, and steps are as follows: (1) vacuum medium-frequency induction melting and stirring: platinum-rhodium alloy is melted and stirred; (2) controlling pouring temperature: alloy melt temperature is reduced to 30-50 DEG C above melting point, and is kept warm; (3) rapid solidification: alloy melt is poured into water-cooled red copper mould and solidified; (4) homogenizing annealing: cast ingot is put into high-temperature furnace and homogenized annealing; (5) rolling strip: cast ingot is rolled into thin strip; (6) laminated thermal diffusion: thin strip is cut, washed and laminated to required thickness, and is hot-diffused and kept pressure, and is pressed into block-shaped alloy ingot; (7) rolling plate: block-shaped alloy ingot is rolled into plate.The method for controlling segregation of platinum-rhodium alloy reduces component segregation through low-temperature pouring and rapid solidification, eliminates intracrystalline segregation by homogenizing annealing, eliminates regional segregation by rolling strip and laminated thermal diffusion, and finally obtains platinum-rhodium alloy plate with uniform microstructure.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of metal materials, in particular to a method for controlling segregation of platinum-rhodium alloy. BACKGROUND

[0002] As an excellent high-temperature alloy material, platinum-rhodium alloy has high melting point, moderate resistivity, excellent high-temperature strength, excellent high-temperature oxidation resistance and corrosion resistance, and good processing performance, and plays an extremely important role in the production of special glass; the segregation control of platinum-rhodium alloy products is related to the uniformity of the material resistivity and high-temperature strength, and is of great significance. SUMMARY

[0003] The purpose of the present application is to overcome the deficiencies in the prior art, and to provide a method for controlling the segregation of platinum-rhodium alloy, which can produce platinum-rhodium alloy plates with no segregation and uniform microstructure, and the segregation degree of the plates is significantly better than that of plates processed by ordinary casting methods; the platinum-rhodium alloy products processed from the plates have uniform resistivity and high-temperature strength, and produce excellent effects in the production of special glass.

[0004] The technical solution adopted by the present application is as follows:

[0005] A method for controlling the segregation of platinum-rhodium alloy, wherein the steps are as follows:

[0006] (1) Vacuum medium-frequency induction melting and stirring: Put the platinum-rhodium alloy with rhodium content of 1-30 wt % after proportioning into the crucible of the vacuum medium-frequency induction melting furnace for melting, and uniformly mix the molten alloy under the action of electromagnetic stirring;

[0007] (2) Control the pouring temperature: After the vacuum degree of the vacuum furnace is reduced to below 20 Pa and the melting-solidification-melting cycle exhausts, slowly reduce the power before pouring, monitor by a dual-color infrared temperature gun, and reduce the temperature of the alloy melt to 30-50℃ above the melting point, and keep the temperature;

[0008] (3) Rapid solidification: Pour the alloy melt into a water-cooled red copper mold at a uniform speed to solidify and obtain an ingot;

[0009] (4) Homogenization annealing: Put the ingot into a high-temperature furnace for homogenization annealing;

[0010] (5) Rolling strip: continuously roll the annealed ingot into a thin strip;

[0011] (6) Laminated thermal diffusion: uniformly cut and wash the thin strip, and stack to the required thickness, and use a high polymer diffusion welding machine for thermal diffusion, and press into a block-shaped alloy ingot after keeping the pressure for a certain time;

[0012] (7) Plate rolling: roll the block-shaped alloy ingot into a plate of the required specification.

[0013] Preferably, the method for controlling segregation of platinum-rhodium alloy, wherein: the intermediate frequency of the vacuum intermediate frequency induction melting furnace in step (1) is 3-5 kHz, and the melting temperature is 1800-1900 ℃.

[0014] Preferably, the method for controlling segregation of platinum-rhodium alloy, wherein: the crucible in step (1) is one of a zirconia crucible, a magnesia crucible, an alumina crucible or a calcia crucible.

[0015] Preferably, the method for controlling segregation of platinum-rhodium alloy, wherein: the content of the main component oxide in the zirconia crucible, the magnesia crucible, the alumina crucible or the calcia crucible is ≥95%.

[0016] Preferably, the method for controlling segregation of platinum-rhodium alloy, wherein: the holding time in step (2) is 30-60 s.

[0017] Preferably, the method for controlling segregation of platinum-rhodium alloy, wherein: the copper mold in step (3) is a vertical mold, the vertical mold cavity has a width of 20-40 mm, a length of 30-50 mm, and a depth of ≥50 mm.

[0018] Preferably, the method for controlling segregation of platinum-rhodium alloy, wherein: the cooling water temperature of the water-cooled copper mold in step (3) is ≤10 ℃.

[0019] Preferably, the method for controlling segregation of platinum-rhodium alloy, wherein: the annealing temperature during homogenization annealing in step (4) is 0.9Tm, Tm is the melting point of the alloy, and the annealing time is 10-15 h.

[0020] Preferably, the method for controlling segregation of platinum-rhodium alloy, wherein: the thickness of the thin strip in step (5) is ≤0.25 mm.

[0021] Preferably, the method for controlling segregation of platinum-rhodium alloy, wherein: the hot diffusion pressure in step (6) is ≥20T, the hot diffusion temperature is 1400-1600 ℃, and the hot diffusion pressure holding time is 10-30 min.

[0022] Advantages of the present application:

[0023] (1) The method for controlling segregation of platinum-rhodium alloy utilizes electromagnetic stirring with a suitable frequency to uniformly mix the alloy melt, reduces composition segregation through low-temperature casting and rapid solidification, eliminates intracrystalline segregation through homogenization annealing, and eliminates regional segregation through rolling strip and stacking hot diffusion.

[0024] (2) The method for controlling the segregation of platinum-rhodium alloy of the present application, the rhodium content of the head and tail of the prepared platinum-rhodium alloy plate is sampled and measured respectively, and the maximum difference is within 0.02%, while the rhodium content difference of the head and tail of the plate prepared by the common "melting-casting-rolling plate" method is generally 0.1-0.5%, and the higher the rhodium content is, the more serious the segregation is, so that the prepared platinum-rhodium alloy plate is of uniform composition and uniform structure by using the preparation method of the present application. DETAILED DESCRIPTION

[0025] The present application is further described below in combination with specific examples.

[0026] Example 1

[0027] A method for controlling the segregation of platinum-rhodium alloy, wherein the steps are as follows:

[0028] (1) Vacuum medium-frequency induction melting and stirring: platinum-rhodium alloy with mass ratio of Pt:Rh=99:1 is placed in an alumina crucible of a frequency of 3 kHz vacuum medium-frequency induction melting furnace for melting, and the melted alloy melt is uniformly mixed under the action of electromagnetic stirring;

[0029] (2) Controlling the casting temperature: the vacuum degree of the vacuum furnace is extracted to 15 Pa, and after the melting-solidification-melting cycle exhaust, the power is slowly reduced before casting, and the alloy melt temperature is reduced to 1820℃ by monitoring with a dual-color infrared temperature measuring gun, and the temperature is maintained for 30s;

[0030] (3) Rapid solidification: the alloy melt is uniformly poured into a water-cooled copper vertical mold with a width of 30mm, a length of 50mm and a depth of 100mm to solidify to obtain an ingot, and the water-cooled copper vertical mold is supplied with 8℃ cooling water provided by an industrial water chiller;

[0031] (4) Homogenization annealing: the ingot is placed in a high-temperature furnace for homogenization annealing, the annealing temperature is 1620℃, and the annealing time is 10h;

[0032] (5) Rolling strip: the annealed ingot is continuously rolled into a thin strip with a thickness of 0.1mm;

[0033] (6) Laminated thermal diffusion: the thin strip is uniformly cut, washed and randomly laminated to a thickness of 25mm, and then subjected to thermal diffusion by using a high polymer diffusion welding machine, the thermal diffusion temperature is 1400℃, the pressure is 30T, and the pressure is maintained for 15min to press into a 21mm thick block-shaped PtRh1 alloy ingot;

[0034] (7) Rolling plate: the obtained block-shaped alloy ingot is rolled into a 1mm thick PtRh1 alloy plate with uniform composition.

[0035] Example 1 The rhodium content of the rolled PtRh1 alloy plate was detected by sampling the head, middle and tail portions, and the rhodium content was 0.99%, 0.99% and 1% respectively, with a maximum difference of 0.01%.

[0036] Example 2

[0037] A method for controlling segregation of a platinum-rhodium alloy, wherein the steps are as follows:

[0038] (1) Vacuum medium-frequency induction melting and stirring: PtRh alloy with a mass ratio of Pt:Rh = 80:20 is placed in a zirconia crucible of a frequency of 4.5 kHz vacuum medium-frequency induction melting furnace for melting, and the molten alloy is uniformly mixed under the action of electromagnetic stirring;

[0039] (2) Control the casting temperature: the vacuum degree of the vacuum furnace is extracted to 15 Pa, and after the melting-solidification-melting cycle exhaust, the power is slowly reduced before casting, and the alloy melt temperature is reduced to 1940°C by monitoring with a dual-color infrared temperature gun, and the temperature is maintained for 30 s;

[0040] (3) Rapid solidification: the alloy melt is uniformly poured into a water-cooled copper vertical mold with a width of 20 mm, a length of 40 mm and a depth of 150 mm to obtain an ingot, and the water-cooled copper vertical mold is supplied with cooling water at a temperature of 5°C provided by an industrial water chiller;

[0041] (4) Homogenization annealing: the ingot is placed in a high-temperature furnace for homogenization annealing, the annealing temperature is 1687°C, and the annealing time is 12 h;

[0042] (5) Rolling strip: the annealed ingot is continuously rolled into a thin strip with a thickness of 0.24 mm;

[0043] (6) Laminated thermal diffusion: the thin strip is uniformly cut, washed and randomly stacked to a thickness of 25 mm, and a high polymer diffusion welding machine is used for thermal diffusion, the thermal diffusion temperature is 1550°C, the pressure is 100T, and the pressure is maintained for 30 min, then the PtRh20 alloy ingot is pressed into a 22mm thick block;

[0044] (7) Plate rolling: the block-shaped alloy ingot is rolled into a 0.5mm thick PtRh20 alloy plate with no segregation.

[0045] Example 2 The rhodium content of the rolled PtRh20 alloy plate was detected by sampling the head, middle and tail portions, and the rhodium content was 19.99%, 19.99% and 19.98% respectively, with a maximum difference of 0.01%.

[0046] Example 3

[0047] A method for controlling segregation of a platinum-rhodium alloy, wherein the steps are as follows:

[0048] (1) Vacuum medium frequency induction smelting stirring: PtRh alloy with mass ratio of Pt:Rh=70:30 is put into zirconia crucible of frequency 5 kHz vacuum medium frequency induction smelting furnace for smelting, and the molten alloy is uniformly mixed under the action of electromagnetic stirring;

[0049] (2) Controlling pouring temperature: the vacuum degree of the vacuum furnace is extracted to 20 Pa, after the melting-solidification-melting cycle exhaust, the power is slowly reduced before pouring, and the alloy melt temperature is reduced to 1970 ℃ by monitoring with a dual-color infrared temperature gun, and the temperature is kept for 30 s;

[0050] (3) Rapid solidification: the alloy melt is uniformly poured into a water-cooled copper vertical mold with a width of 20 mm, a length of 40 mm and a depth of 200 mm to obtain an ingot, and the water-cooled copper vertical mold is supplied with 5 ℃ cooling water provided by an industrial water chiller;

[0051] (4) Homogenization annealing: the ingot is put into a high-temperature furnace for homogenization annealing, the annealing temperature is 1710 ℃, and the annealing time is 15 h;

[0052] (5) Rolling strip: the annealed ingot is continuously rolled into a thin strip with a thickness of 0.2 mm;

[0053] (6) Laminated thermal diffusion: the thin strip is uniformly cut, washed, and randomly laminated to a thickness of 25 mm, and a high polymer diffusion welding machine is used for thermal diffusion, the thermal diffusion temperature is 1600 ℃, the pressure is 100T, and the pressure is kept for 30 min, then the PtRh30 alloy ingot is pressed into a 22.3 mm thick block;

[0054] (7) Rolling plate: the obtained block-shaped alloy ingot is rolled into a 1.0 mm thick PtRh30 alloy plate.

[0055] The rhodium content of the PtRh30 alloy plate rolled in Example 3 is detected respectively from the first, middle and tail parts, and the rhodium content is 29.98%, 29.99% and 29.97% respectively, and the maximum difference is 0.02%.

[0056] Comparative Example 1

[0057] A method for controlling the segregation of platinum-rhodium alloy, wherein the steps are as follows:

[0058] (1) Vacuum induction smelting: PtRh alloy with mass ratio of Pt:Rh=70:30 is put into zirconia crucible of frequency 5 kHz vacuum medium frequency induction smelting furnace for smelting, and the molten alloy is uniformly mixed under the action of electromagnetic stirring;

[0059] (2) Casting: The vacuum degree of the vacuum furnace is drawn to 20 Pa, and after the melting-solidifying-melting cycle exhaust, it is directly cast in the water-cooled vertical copper mold with the width of 20 mm, the length of 40 mm and the depth of 200 mm at 2090℃. The cooling water in the copper mold is not cooled by the industrial water chiller, and the water temperature is 29℃;

[0060] (3) Rolling: The obtained block-shaped alloy ingot is rolled into a 1.0mm thick PtRh30 alloy plate.

[0061] The rhodium content of the PtRh30 alloy plate rolled in the comparative example 1 is sampled and detected respectively from the first, middle and tail parts, and the rhodium content mass fraction is 29.77%, 29.96% and 30.23% respectively, and the maximum difference is 0.46%.

[0062] Finally, it should be explained that the above specific embodiments are only used to illustrate the technical solutions of the present application but not limit the present application. Although the present application is described in detail with reference to the examples, those skilled in the art should understand that the technical solutions of the present application can be modified or replaced equivalently without departing from the spirit and scope of the technical solutions of the present application, and they should be covered in the scope of the claims of the present application.

Claims

1. A method for controlling the segregation of platinum-rhodium alloys, characterized in that: Here are the steps: (1) Vacuum medium frequency induction melting and stirring: The proportioned platinum-rhodium alloy is placed in the crucible of a vacuum medium frequency induction melting furnace for melting. The melted alloy liquid is uniformly mixed under the action of electromagnetic stirring; (2) Control the casting temperature: evacuate the vacuum furnace to below 20 Pa, exhaust the vacuum through the melting-solidification-melting cycle, and then slowly reduce the power before casting. Use a two-color infrared temperature measuring gun to monitor the temperature of the alloy melt to 30-50°C above the melting point and keep it warm. (3) Rapid solidification: The alloy melt is poured into a water-cooled copper mold at a uniform speed and solidified to obtain an ingot; (4) Homogenization annealing: Place the ingot in a high-temperature furnace for homogenization annealing; (5) Strip rolling: the annealed ingot is continuously rolled into thin strips; (6) Laminated thermal diffusion: The thin strip is cut and cleaned uniformly, and laminated to the required thickness. A polymer diffusion welding machine is used for thermal diffusion. After holding the pressure for a certain period of time, it is pressed into a block-shaped alloy ingot; (7) Plate rolling: The block-shaped alloy ingot is rolled into plates of the required specifications; Step (1) The medium frequency of the vacuum medium frequency induction melting furnace is 3-5 kHz, and the melting temperature is 1800-1900°C; The holding time in step (2) is 30-60 seconds; The annealing temperature during the homogenization annealing in step (4) is 0.9Tm, and the annealing time is 10-15h; Step (5) the thickness of the thin strip is ≤ 0.25 mm; In step (6), the thermal diffusion pressure is ≥20T, the thermal diffusion temperature is 1400-1600°C, and the thermal diffusion holding time is 10-30min.

2. The method for controlling the segregation of a platinum-rhodium alloy as claimed in claim 1, wherein: The crucible in step (1) is one of a zirconia crucible, a magnesia crucible, an alumina crucible or a calcium oxide crucible.

3. The method for controlling the segregation of a platinum-rhodium alloy as claimed in claim 2, wherein: The content of the main component of oxide in the zirconia crucible, magnesia crucible, alumina crucible or calcium oxide crucible is ≥95%.

4. The method for controlling the segregation of a platinum-rhodium alloy as claimed in claim 1, wherein: Step (3) The copper mold is a vertical mold with a mold cavity width of 20-40 mm, a length of 30-50 mm, and a depth of ≥50 mm.

5. The method for controlling segregation of platinum-rhodium alloy according to claim 1, wherein: Step (3) The temperature of the cooling water for the water-cooled copper mold is ≤10°C.