Preparation method of high-purity ytterbium target material for OLED

Abstract

The application belongs to the technical field of metal target production, and specifically discloses a preparation method of high-purity ytterbium target for OLEDs, which comprises the following specific steps: high-purity ytterbium metal is loaded into a smelting furnace, a three-stage pump system is used to perform vacuum pumping, the furnace baking and smelting temperatures are strictly controlled, the molten liquid is cast into a centrifugal mold after refining, centrifugation is maintained, and cutting and finishing are performed after argon filling and cooling. Through accurate process control, the application ensures that the product is free of defects such as black spots and inclusions, the dimensional tolerance is controlled within ±0.1 mm, and the surface roughness is less than or equal to 3.2 microns, thereby meeting the requirements of the OLED industry for high-purity and high-performance target materials. Through the combination of centrifugal casting technology and a high-vacuum smelting environment, the application significantly improves the production efficiency and product quality of high-purity ytterbium target materials, reduces the production cost, and meets the demand of the OLED industry for high-purity and high-performance target materials.

Description

Technical Field

[0001] This invention belongs to the field of metal target production technology, specifically relating to a method for preparing high-purity ytterbium target material for OLEDs. Background Technology

[0002] OLED (Organic Light Emitting Diode) display technology, with its excellent display effect, thin and light structure, and low power consumption, has gradually become one of the mainstream technologies in the electronic display industry. In the manufacturing process of OLEDs, the selection of the cathode material plays a crucial role in improving the characteristics of top-emitting organic electroluminescence. Currently, MgAg alloy is commonly used as the cathode metal in the industry. However, with continuous technological advancements and increasingly demanding display performance requirements, people are beginning to seek more ideal cathode materials, and high-purity ytterbium metal targets are gradually gaining attention due to their unique properties. High-purity ytterbium metal targets belong to rare-earth metal targets and possess unique optical, electrical, and magnetic properties, which give them broad application prospects in the OLED industry. However, despite the significant performance advantages of high-purity ytterbium metal targets, their preparation process faces numerous technical challenges and difficulties.

[0003] Existing patent CN 118996350A discloses a conventional production process for high-purity ytterbium metal sputtering targets, primarily employing directional solidification. This process includes raw material extrusion, directional solidification, and mold removal. The melting time is relatively long, typically 2-6 hours. This extended process not only increases production costs but also makes it difficult to effectively control the oxidation of the ytterbium sputtering target. Oxidation easily leads to defects such as black spots, severely impacting the quality and performance of the target. Furthermore, the directional solidification mold needs to be removed after use and cannot be reused, further reducing production efficiency, increasing costs, and limiting the large-scale production and application of high-purity ytterbium metal sputtering targets. Another patent, CN 112442622A, discloses a production process for ytterbium metal sputtering targets involving turning and plastic forming after vacuum melting. While this process utilizes a vacuum environment to some extent to reduce the possibility of oxidation, its relatively long production process, involving multiple steps such as hot forging, rolling, and heat treatment, still makes ytterbium metal prone to oxidation. Oxidation not only leads to material loss but also increases the defect rate of products, thereby increasing the production cost of high-purity ytterbium metal sputtering targets and hindering their widespread application in the OLED industry.

[0004] In summary, existing high-purity ytterbium metal sputtering targets suffer from problems such as long production processes, difficulty in controlling oxidation, low production efficiency, and high production costs. These issues severely restrict the development and application of high-purity ytterbium metal sputtering targets in the OLED industry. Therefore, it is essential to develop a new method for preparing high-purity ytterbium metal sputtering targets. Summary of the Invention

[0005] The purpose of this invention is to overcome the defects of the existing technology and provide a method for preparing high-purity ytterbium target material for OLEDs. The method uses centrifugal casting to produce the target material. Through the action of centrifugal force, the molten ytterbium metal is evenly distributed in the mold, which effectively improves the density of the ytterbium target ingot, refines the grain structure, effectively controls the location of defects and reduces the formation of defects.

[0006] In OLED manufacturing, improving the top-emission organic electroluminescence characteristics of the cathode plays a crucial role. Currently, MgAg alloy is commonly used as the cathode metal. To further reduce the injection barrier, a nanolayer of functional materials, such as LiF, Cs, Rb, and Yb, can be embedded beneath the MgAg. In actual production, due to the poor stability of LiF production, doping with Yb is a better option. Studies have shown that embedding a Yb nanolayer beneath MgAg can effectively reduce color shift and power consumption, and improve device efficiency and lifespan.

[0007] To achieve the above objectives, one of the technical solutions of the present invention is: a method for preparing a high-purity ytterbium target material for OLEDs, comprising the following steps:

[0008] (1) Load the bulk metal ytterbium into the crucible of the high vacuum medium frequency induction melting furnace;

[0009] (2) Install the centrifugal casting mold onto the centrifugal mechanism, use a dial indicator to measure the eccentricity of the centrifugal casting mold, and control the concentricity.

[0010] (3) Use a three-stage pump to evacuate the equipment, then close the vacuum valve and control the pressure rise; if the pressure rise does not meet the requirements, check for leaks and repeat the vacuuming and pressure rise measurement operations until the pressure rise meets the requirements before proceeding with subsequent operations.

[0011] (4) Open the vacuum valve, bake the furnace at low power, control the baking time and the maximum baking temperature, close the vacuum valve after baking is completed, and fill with argon gas;

[0012] (5) Increase the smelting power, heat up to the point where the ytterbium melts, then keep it in heat for refining, open the vacuum valve for gas exchange refining, and close the vacuum valve after the required vacuum level is reached.

[0013] (6) Turn on the centrifuge mechanism and set the speed. After the speed stabilizes, pour the refined ytterbium molten metal into the centrifuge mold, maintain centrifugation for a period of time, and then stop centrifugation.

[0014] (7) Argon gas is introduced for cooling. After argon is introduced, the furnace pressure is controlled. After sufficient cooling, the furnace temperature is controlled, and the furnace is removed and demolded.

[0015] (8) Cut, turn and finish the ytterbium target ingots after melting and casting according to the size requirements. During the processing, strictly control the ambient temperature and relative humidity.

[0016] In a preferred embodiment of the present invention, in step (1), the RE content of the bulk ytterbium is ≥99.9%, and the Yb purity is ≥99.99%.

[0017] In a preferred embodiment of the present invention, the centrifugal speed in step (2) is 40-60 rpm, and the concentricity is controlled within 0.5 mm.

[0018] In a preferred embodiment of the present invention, the three-stage pump in step (3) consists of a slide valve pump, a Roots pump, and a diffusion pump, and is used to evacuate to a vacuum level of 1×10⁻⁶. -2 -3×10 -2 The pressure rise is controlled at 0.3-0.7 Pa / h.

[0019] In a preferred embodiment of the present invention, the furnace baking time in step (4) is 3-15 minutes, the maximum furnace baking temperature is 300-500°C, and the argon gas is purged to a pressure of 4×10⁻⁶. 3 -8×10 3 Pa.

[0020] In a preferred embodiment of the present invention, in step (5), the temperature is raised to 950-1050°C, and the refining is carried out for 3-5 minutes, requiring a vacuum degree of 1×10⁻⁶. 3 -4×10 3 Pa.

[0021] In a preferred embodiment of the present invention, the rotation speed in step (6) is 200-1200 rpm and the centrifugation time is 5-10 min.

[0022] In a preferred embodiment of the present invention, the furnace pressure is controlled at 4 × 10⁻⁶ in step (7). 3 -8×10 3 Pa, cooling time is 60-90 min, and the furnace exit temperature is controlled to be ≤100℃.

[0023] In a preferred embodiment of the present invention, the dimensional tolerance in step (8) is ±0.1 mm, the surface roughness is ≤3.2 μm, the processing ambient temperature is ≤30℃, and the processing ambient relative humidity is ≤40%RH.

[0024] To achieve the above objectives, the second technical solution of the present invention is: a high-purity ytterbium target material prepared by the above-mentioned method for preparing high-purity ytterbium target material for OLEDs.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] 1. This invention uses centrifugal casting technology to significantly improve the density of ingots, reduce internal defects such as porosity and inclusions, and improve the mechanical and optical properties of the product; the product appearance is free of defects such as black spots, inclusions, and scratches.

[0027] 2. This invention uses centrifugal casting technology, which reduces the wear and tear of molds in traditional directional solidification processes. The molds can be reused, thus reducing production costs.

[0028] 3. The production process of this invention reduces smelting time and subsequent processing steps, improves production efficiency, and further reduces production costs;

[0029] 4. This invention utilizes a high-vacuum melting environment to effectively reduce the oxidation reaction of ytterbium metal, avoiding material loss and increased product defect rates caused by oxidation; through strict vacuum and temperature control, the purity of the melting process is ensured, thereby improving the product yield.

[0030] 5. The high-purity ytterbium metal target produced by this invention meets the requirements of the OLED industry for high-purity materials. Through optimized post-processing, the product size tolerance is controlled within ±0.1mm and the surface roughness is ≤3.2μm, which meets the high precision requirements of the target material in OLED production. Attached Figure Description

[0031] Figure 1 A schematic diagram of the centrifugal casting mold in Embodiment 1 of the present invention;

[0032] Figure 2 Schematic diagram of the centrifugal casting mold in Embodiment 2 of the present invention;

[0033] Figure 3 A schematic diagram of the centrifugal casting mold in Embodiment 3 of the present invention;

[0034] Figure 4 Appearance drawing of the ytterbium metal target material in Embodiment 1 of this invention;

[0035] Figure 5 Images of ytterbium targets subjected to water immersion nondestructive testing (C-Scan) in Examples 1-3 of this invention. Detailed Implementation

[0036] To make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be described in more detail below with reference to the accompanying drawings and specific embodiments, but the scope of protection of the present invention is not limited to these embodiments.

[0037] Example 1

[0038] (1) Weigh (14±1) kg of bulk ytterbium with RE≥99.9% and Yb purity≥99.99%, and put the bulk ytterbium into the crucible of the high vacuum medium frequency induction melting furnace.

[0039] (2) Centrifugal casting mechanism (such as Figure 1 (As shown) Install it on the centrifuge mechanism, rotate at 50 rpm, use a dial indicator to measure the eccentricity of the centrifugal casting mold, and control the concentricity within 0.5 mm;

[0040] (3) Use a three-stage pump consisting of a slide valve pump, a Roots pump, and a diffusion pump to evacuate the equipment to a vacuum level of 2×10⁻⁶. -2 Pa, close the vacuum valve, and control the pressure rise at 0.5 Pa / h;

[0041] (4) Open the vacuum valve, heat the furnace at low power, control the heating time to 3 minutes, and the maximum heating temperature to 300℃. After heating is complete, close the vacuum valve and purge with argon gas to 6×10⁻⁶. 3 Pa;

[0042] (5) Increase the melting power, raise the temperature to 950℃, and after the ytterbium metal melts, hold it at that temperature for 3 minutes for refining. Then, open the vacuum valve to ventilate and refine, achieving a vacuum level of 4×10⁻⁶. 3 After Pa, close the vacuum valve;

[0043] (6) Turn on the centrifuge and set the speed to 200 rpm. After the speed stabilizes, pour the refined ytterbium molten metal into the centrifuge mold and maintain centrifugation for 5 minutes before stopping the centrifugation.

[0044] (7) Argon purging and cooling; after argon purging, the furnace pressure is controlled at 6×10⁻⁶. 3 Pa, cool for 65 minutes, control the oven temperature to 80℃, and then perform the oven discharge and demolding operations;

[0045] (8) Cut, turn, and finish the ytterbium target ingots after melting and casting according to the size requirements, control the dimensional tolerance to ±0.1mm, the surface roughness to 1.68μm, and the ambient temperature and relative humidity during the processing to 26℃ and 34RH.

[0046] The machining tolerance test results are shown in Table 1. The entire sample was placed in the testing medium and ultrasonic testing was performed. The test results are detailed in Table 2. The water immersion non-destructive testing (C-Scan) diagram is shown in Table 2. Figure 5 Left 1; Observe the appearance of the product and find no defects such as black spots, inclusions, or scratches. The product appearance photo is as follows. Figure 4 As shown.

[0047] Example 2

[0048] (1) Weigh (28±1) kg of bulk ytterbium with RE≥99.9% and Yb purity≥99.99%, and put the bulk ytterbium into the crucible of the high vacuum medium frequency induction melting furnace.

[0049] (2) Centrifugal casting mold (such as...) Figure 2 (As shown) Install it on the centrifuge mechanism, rotate at 50 rpm, use a dial indicator to measure the eccentricity of the centrifugal casting mold, and control the concentricity within 0.5 mm;

[0050] (3) Use a three-stage pump consisting of a slide valve pump, a Roots pump, and a diffusion pump to evacuate the equipment to a vacuum level of 2×10⁻⁶. -2 Pa, close the vacuum valve, and control the pressure rise at 0.5 Pa / h;

[0051] (4) Open the vacuum valve, heat the furnace at low power, control the heating time to 6 minutes, and the maximum heating temperature to 400℃. After heating is complete, close the vacuum valve and purge with argon gas to 6×10⁻⁶. 3 Pa;

[0052] (5) Increase the melting power, raise the temperature to 1000℃, and after the ytterbium metal melts, hold it at that temperature for 4 minutes for refining. Then, open the vacuum valve to ventilate and refine, achieving a vacuum level of 2.5 × 10⁻⁶. 3 After Pa, close the vacuum valve;

[0053] (6) Turn on the centrifuge and set the speed to 600 rpm. After the speed stabilizes, pour the refined ytterbium molten metal into the centrifuge mold and maintain centrifugation for 7 minutes before stopping the centrifugation.

[0054] (7) Argon purging and cooling; after argon purging, the furnace pressure is controlled at 6×10⁻⁶. 3 Pa, cool for 70 minutes, control the oven temperature to 80℃, and then perform the oven unloading and demolding operations;

[0055] (8) Cut, turn, and finish the ytterbium target ingots after melting and casting according to the size requirements, control the dimensional tolerance to ±0.1mm, the surface roughness to 2.12μm, and the ambient temperature during the processing to ≤24℃ and the relative humidity to 33RH.

[0056] The machining tolerance test results are shown in Table 1. The entire sample was placed in the testing medium and ultrasonic testing was performed. The test results are detailed in Table 2. The water immersion non-destructive testing (C-Scan) diagram is shown in Table 2. Figure 5 Left 2; Observe the appearance of the product and find no defects such as black spots, inclusions, or scratches.

[0057] Example 3

[0058] (1) Weigh (52±1) kg of bulk ytterbium with composition satisfying RE≥99.9% and Yb purity≥99.99%, and put the bulk ytterbium into the crucible of the high vacuum medium frequency induction melting furnace;

[0059] (2) Centrifugal casting mold (such as...) Figure 3 (As shown) Install it on the centrifuge mechanism, rotate at 50 rpm, use a dial indicator to measure the eccentricity of the centrifugal casting mold, and control the concentricity within 0.5 mm;

[0060] (3) Using a three-stage pump consisting of a slide valve pump, a Roots pump, and a diffusion pump, the equipment vacuum was evacuated to 2 × 10⁻⁶. -2 Pa, close the vacuum valve, and control the pressure rise at 0.5 Pa / h;

[0061] (4) Open the vacuum valve, heat the furnace at low power for 15 minutes, and set the maximum furnace temperature to 500℃. After heating is complete, close the vacuum valve and purge with argon gas to a level of 6×10⁻⁶. 3 Pa;

[0062] (5) Increase the melting power, raise the temperature to 1050℃, and after the ytterbium metal melts, hold it at that temperature for 5 minutes for refining. Then, open the vacuum valve to ventilate and refine, and adjust the vacuum level to 1×10⁻⁶. 3 After Pa, close the vacuum valve;

[0063] (6) Turn on the centrifuge and set the speed to 1000 rpm. After the speed stabilizes, pour the refined ytterbium molten metal into the centrifuge mold and maintain centrifugation for 10 minutes before stopping the centrifugation.

[0064] (7) Argon purging and cooling; after argon purging, the furnace pressure is controlled at 6×10⁻⁶. 3 Pa, cool for 90 minutes, control the oven temperature to 85℃, and then perform the oven discharge and demolding operations;

[0065] (8) Cut, turn, and finish the ytterbium target ingots after melting and casting according to the size requirements, control the dimensional tolerance to ±0.1mm, the surface roughness to 1.66μm, and the ambient temperature and relative humidity during the processing to 26℃ and 31RH.

[0066] The machining tolerance test results are shown in Table 1. The entire sample was placed in the testing medium and ultrasonic testing was performed. The test results are detailed in Table 2. The water immersion non-destructive testing (C-Scan) diagram is shown in Table 2. Figure 5 Left 3; Observe the appearance of the product and find no defects such as black spots, inclusions, or scratches.

[0067] Table 1. Results of machining tolerance tests on the ytterbium metal sputtering materials prepared in Examples 1-3.

[0068]

[0069] Table 2. Flaw detection test results of the ytterbium metal targets prepared in Examples 1-3.

[0070]

[0071] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a high-purity ytterbium target for OLEDs, characterized in that, Includes the following steps: (1) Load the bulk metal ytterbium into the crucible of the high vacuum medium frequency induction melting furnace; (2) Install the centrifugal casting mold onto the centrifugal mechanism, use a dial indicator to measure the eccentricity of the centrifugal casting mold, and control the concentricity. (3) Use a three-stage pump to evacuate the equipment, then close the vacuum valve and control the pressure rise; if the pressure rise does not meet the requirements, check for leaks and repeat the vacuuming and pressure rise measurement operations until the pressure rise meets the requirements before proceeding with subsequent operations. (4) Open the vacuum valve, bake the furnace at low power, control the baking time and the maximum baking temperature, close the vacuum valve after baking is completed, and fill with argon gas; (5) Increase the smelting power, heat up to the point where the ytterbium melts, then keep it in heat for refining, open the vacuum valve for gas exchange refining, and close the vacuum valve after the required vacuum level is reached. (6) Turn on the centrifuge mechanism and set the speed. After the speed stabilizes, pour the refined ytterbium molten metal into the centrifuge mold, maintain centrifugation for a period of time, and then stop centrifugation. (7) Argon gas is introduced for cooling. After argon is introduced, the furnace pressure is controlled. After sufficient cooling, the furnace temperature is controlled, and the furnace is removed and demolded. (8) Cut, turn and finish the ytterbium target ingots after melting and casting according to the size requirements. During the processing, strictly control the ambient temperature and relative humidity.

2. The method for preparing high-purity ytterbium target material for OLEDs as described in claim 1, characterized in that, In step (1), the bulk ytterbium contains RE ≥ 99.9% and Yb purity ≥ 99.99%.

3. The method for preparing high-purity ytterbium target material for OLEDs as described in claim 1, characterized in that, In step (2), the centrifugation speed is 40-60 rpm, and the concentricity is controlled within 0.5 mm.

4. The method for preparing high-purity ytterbium target material for OLEDs as described in claim 1, characterized in that, In step (3), the three-stage pump consists of a slide valve pump, a Roots pump, and a diffusion pump, and is used to evacuate to a vacuum level of 1×10⁻⁶. -2 -3×10 -2 The pressure rise is controlled at 0.3-0.7 Pa / h.

5. The method for preparing high-purity ytterbium target material for OLEDs as described in claim 1, characterized in that, In step (4), the furnace drying time is 3-15 minutes, the maximum furnace drying temperature is 300-500℃, and argon gas is purged to a pressure of 4×10⁻⁶. 3 -8×10 3 Pa.

6. The method for preparing high-purity ytterbium target material for OLEDs as described in claim 1, characterized in that, In step (5), the temperature is raised to 950-1050℃, and the refining process is carried out for 3-5 minutes. The required vacuum degree is 1×10⁻⁶. 3 -4×10 3 Pa.

7. The method for preparing high-purity ytterbium target material for OLEDs as described in claim 1, characterized in that, In step (6), the rotation speed is 200-1200 rpm and the centrifugation time is 5-10 min.

8. The method for preparing high-purity ytterbium target material for OLEDs as described in claim 1, characterized in that, In step (7), the furnace pressure is controlled at 4×10 3 -8×10 3 Pa, cooling time is 60-90 min, and the furnace exit temperature is controlled to be ≤100℃.

9. The method for preparing high-purity ytterbium target material for OLEDs as described in claim 1, characterized in that, In step (8), the dimensional tolerance is ±0.1 mm, the surface roughness is ≤3.2 μm, the ambient temperature is ≤30℃, and the relative humidity is ≤40%RH.

10. A high-purity ytterbium target material for OLEDs prepared by the method described in any one of claims 1-9.

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