Preparation method of high-purity manganese target material

Abstract

The application relates to a preparation method of high-purity manganese target material, and belongs to the technical field of metallurgy, which comprises the following steps: firstly, manganese powder is dried, then the manganese powder is poured into a graphite mold and placed into a joule heat sintering furnace for sintering; during sintering, a two-stage pre-pressing and four-stage gradient pressing strategy is implemented, low-temperature sintering is realized, stress and cracking in the cooling process are avoided through two-stage cooling after sintering, the temperature and time of each stage are accurately controlled, and the defects of high heating temperature and long holding time are avoided. The application simplifies the production process as a whole, controls the effective step-by-step release of internal stress at different temperatures, reduces porosity, avoids sintering cracking, optimizes the sintering atmosphere of each stage, avoids the influence of impurities such as oxygen in the air on the purity of the sintered manganese target material, and realizes the purpose of preparing high-purity manganese target material with low energy consumption, high efficiency and high quality.

Description

Technical Field

[0001] This invention belongs to the field of metallurgical technology, and particularly relates to a method for preparing high-purity manganese targets. Background Technology

[0002] In the microelectronics industry, manganese sputtering targets are commonly used to fabricate various integrated circuits and microchips. In the optoelectronics industry, they are frequently used to create thin-film materials for optoelectronic devices such as LEDs and solar cells. In the magnetic recording industry, manganese sputtering targets are often used to fabricate magnetic films for hard disk drives. Due to their unique properties, manganese sputtering targets play a vital role in many technological fields.

[0003] Most of the currently disclosed patents only relate to the preparation of manganese alloy targets. CN115338374A discloses a method for preparing ultra-high purity copper-manganese ingots for semiconductor targets. Through multiple pressure regulation and heating processes, copper liquid is mixed with manganese raw materials to obtain an ultra-high purity copper-manganese alloy liquid, which is then cast. This effectively solves the elemental segregation problem in the production process of copper-manganese alloy targets. However, this method requires multiple pressure regulation and heating processes, making the process relatively complex. It also requires high-precision melting equipment, placing high demands on the equipment. CN106399954A discloses a processing method for long-life copper-manganese alloy targets. It uses conventional thermomechanical treatment methods to process the copper-manganese alloy ingots to obtain the original billet; the original billet is then subjected to friction stirring to refine the grains, improving the lifespan of the target. However, this method is mainly applicable to copper-manganese alloys and is not suitable for other types of targets, and its processing efficiency is relatively low. The technical solutions of patents CN115338374A and CN106399954 lack appropriate protective measures during the sintering process, which may lead to oxidation on or inside the target material, thereby increasing the oxygen content. CN117758087A discloses a casting and melting method for ultra-high purity copper-manganese alloy sputtering targets, using a vacuum suspension melting furnace for melting and refining, solving the problem of excessive impurity content in traditional methods. However, due to the complexity of the process, the production efficiency of these patented methods is somewhat limited.

[0004] Regarding the preparation of metallic manganese, CN113862495A discloses a method for preparing high-purity manganese through vacuum distillation, sandblasting, and acid washing. CN115948769A discloses a method for preparing high-purity metallic manganese using electrolysis; however, this technology uses manganese sulfate for electrolytic preparation of manganese, resulting in manganese containing a large amount of sulfur and oxygen impurities, reducing product quality. CN105200453A discloses a method for preparing high-purity manganese by electrolysis, which uses secondary electrolytic refining to deeply remove impurities and improve the purity of the manganese product. However, this process has high energy consumption, causes serious environmental pollution, and has a relatively complex process flow, while gaseous impurities are uncontrollable. CN103114303A discloses a deep purification process and additives for the production of high-purity selenium-free electrolytic metallic manganese. This process uses additives to purify the electrolyte before preparing metallic manganese by electrolysis. It requires precise control of the additive content, has a complex process flow, and the additives themselves are equivalent to introducing new impurities. The cost is also relatively high, and it may cause some environmental pollution.

[0005] Crucially, the preparation of high-purity manganese sputtering targets faces a series of technical challenges arising from the unique properties of manganese. As a transition metal, manganese possesses high chemical activity, a low melting point (1246℃), and high vapor pressure, making it highly susceptible to oxidation and volatilization during high-temperature processing. Furthermore, manganese undergoes complex allotropic transformations in the solid state (α, β, γ, and δ crystal forms), accompanied by significant volume changes during phase transformations, leading to cracks and deformation in the sintered body. These characteristics make the preparation of high-purity manganese sputtering targets more difficult than that of general metal sputtering targets, particularly in terms of densification control and microstructure uniformity. Moreover, the strong affinity of manganese for oxygen results in prominent oxide inclusions. Regarding densification, conventional vacuum sintering, due to its low thermal efficiency and insufficient upper temperature limit, struggles to achieve sufficient diffusion creep, resulting in a product relative density generally below 95%, and the formation of open and closed pore defects. These problems can lead to particulate contamination during the sputtering process, increased thin film resistivity, uneven sputtering rate and fluctuating thin film thickness, reduced target utilization and shortened lifespan, and arc discharge during the sputtering process, resulting in a decrease in yield.

[0006] To date, there is a lack of corresponding preparation technologies both domestically and internationally for the efficient and high-quality preparation of high-purity manganese targets. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to provide a method for preparing high-purity manganese targets at low temperature, low cost and high quality using a Joule heating sintering furnace.

[0008] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a method for preparing high-purity manganese target material, comprising the following steps:

[0009] S1. Prepare the raw material powder:

[0010] Manganese powder is used as a sintering raw material. According to the product specifications, the required mass of manganese powder is weighed using a balance. Then, the manganese powder is placed in a stainless steel pan and then placed in a vacuum drying oven. After the vacuum degree is ≤0.5Pa at room temperature, the temperature is raised and dried at 100~130℃ for 2~6 hours to remove the moisture and complete the preparation of the raw material powder.

[0011] Furthermore, the manganese powder has a purity of not less than 99.7%, and contains Fe ≤ 0.02%, S ≤ 0.02%, P ≤ 0.01%, C ≤ 0.02%, Si ≤ 0.01%, O ≤ 0.2%, with a powder particle size of 200–400 mesh.

[0012] S2, Loading:

[0013] Select a graphite mold of appropriate specifications according to the product size, and make graphite paper for sintering according to the inner cavity size of the mold.

[0014] First, cover the inner wall of the graphite mold cavity and the surface of the lower pressure head or pad with graphite paper to ensure that the graphite mold and manganese powder do not come into direct contact. Then, pour the raw material powder prepared in step S1 into the graphite mold, place 1-2 layers of graphite paper on top of the raw material powder, cover the outside of the graphite mold with a layer of heat-insulating asbestos felt, and then insert the upper pressure head into the mold cavity. After placing the loaded graphite mold into the Joule heating sintering furnace, apply a pre-pressure of 8-14 MPa, close the furnace door, and start evacuating the Joule heating sintering furnace to complete the loading.

[0015] Furthermore, the graphite paper has a thickness of 0.1–0.2 mm, a carbon content higher than 99%, a tensile strength ≥ 4.0 MPa, a sulfur content ≤ 300 ppm, and a chlorine content ≤ 35 ppm.

[0016] Furthermore, the asbestos felt is a high-temperature asbestos felt (temperature resistant above 1000℃), with a thickness of ≥7mm. The size of the asbestos felt is determined according to the size of the outer surface of the sintering mold. The surface area of ​​the unfolded asbestos felt needs to be larger than the outer surface area of ​​the mold. The length and width of the asbestos felt are 3-7mm higher than the outer dimensions of the graphite mold to ensure complete coverage of the outer surface of the graphite mold.

[0017] Furthermore, both the upper and lower pressure heads are made of graphite and are required to have a pressure resistance of not less than 90 MPa.

[0018] S3, Sintering:

[0019] When the vacuum degree inside the Joule heating sintering furnace is less than 8×10 -3After reaching Pa, the temperature is raised, with the pre-pressure reduced to 5–8 MPa at the beginning of the heating process, and the heating rate at 30–60 °C / min. When the temperature reaches 300 °C, the heating rate is reduced to 30–15 °C / min. From the initial temperature rise to 420 °C to the sintering temperature, pressure is applied in four stages, increasing by 5–10 MPa each time, maintaining the pressure for 30 seconds, and then increasing it again, gradually increasing the pressure to 25–48 MPa. After heating to 500 °C, the temperature is held for 100–200 seconds, and then the temperature is raised to the sintering temperature (540–600 °C) at a rate of 15–30 °C / min, and held again for 500–800 seconds. After the holding period, the pressure is completely released at once, and the temperature is lowered from the sintering temperature to 350 °C at a rate of 30–15 °C / min, and then lowered to below 100 °C at a rate of 50–30 °C / s. Throughout the cooling process, the vacuum level is maintained at a level better than 10. -2 Pa, sintering is complete.

[0020] S4. Unloading and Inspection:

[0021] After completing the sintering in step S3, the vacuum is closed and the gas is released. The Joule heating sintering furnace door is opened and the graphite mold is removed. The graphite mold is pressed into a manganese target product using a press. The graphite on the surface of the manganese target product is removed by sanding with fine sandpaper. The chemical composition, density and hardness of the manganese target product are measured. After the analysis is qualified, it is packaged and stored to complete the preparation of the manganese target.

[0022] In summary, the beneficial effects of the present invention are as follows:

[0023] (1) Manganese has a melting point of 1246℃ and a boiling point of 2061℃. However, in high-temperature environments above 1200℃, the saturated vapor pressure of manganese increases exponentially, resulting in a large amount of manganese volatilization.

[0024] This invention utilizes a Joule heating sintering furnace to prepare manganese powder. By taking advantage of the Joule heating effect generated when a large current passes through the powder particles, the temperature of the local area at the contact point rises sharply, while the overall heating temperature of the manganese powder remains very low. Therefore, the preparation of manganese targets using a Joule heating sintering furnace has the characteristics of rapid heating and low-temperature sintering, resulting in fast heating speed, short process, and significant savings in production costs, making it suitable for mass production.

[0025] (2) Manganese undergoes complex allotropic transformations in the solid state. Below 707℃, it is the α-Mn phase; between 707℃ and 1087℃, it is the β-Mn phase; between 1087℃ and 1137℃, it is the γ-Mn phase; and above 1137℃, it is the δ-Mn phase. Significant volume changes accompany these phase transformations, leading to cracks and deformation in the sintered body. Furthermore, conventional atmosphere control systems struggle to establish dynamic pressure balance during high-temperature sintering—insufficient vacuum results in residual oxygen causing oxidation, while excessively high vacuum exacerbates volatilization.

[0026] This invention controls the overall heating temperature at a low temperature in the α phase region, avoiding phase transformation during the sintering process of the powder particles, thereby avoiding the defect of fracture caused by cracks in the sintered body. It also solves the problems of manganese volatilization at high temperatures and the formation of a brittle layer by manganese reacting with the graphite mold.

[0027] (3) Existing processes for preparing manganese targets generally rely on multiple complex steps, such as pre-pressing, sintering, hot isostatic pressing, and heat treatment. This not only increases production costs but also introduces the risk of secondary pollution and reduces the yield. Although it is possible to manufacture targets by smelting and casting into ingots and then cutting them, the saturated vapor pressure of manganese increases exponentially when the temperature exceeds 1200℃, resulting in a material loss rate as high as 15-20%. At the same time, the volatiles condense in the furnace and pollute the heating element and insulation layer, forming a vicious cycle.

[0028] The present invention utilizes the high self-diffusion coefficient of α-Mn to promote the formation of the neck of the sintered powder through low-temperature sintering, and uses the characteristic of a sharp increase in temperature in the local area of ​​the powder particle contact point to match the moderate diffusion ability of γ-Mn to achieve porosity elimination. In the δ-Mn phase region, the surface energy is reduced to complete the grain boundary optimization, thereby improving the density of the manganese target material to better than 95%.

[0029] (4) There are many technical bottlenecks in the rapid preparation of manganese targets using Joule heating furnaces. First, the rapid heating rate leads to uneven heat distribution in the furnace, resulting in temperature differences at different heating points, which in turn leads to poor sintering uniformity and defects such as uneven microstructure, color spots and color differences, soft spots, and pores. Second, the rapid heating rate also leads to large differences in thermal stress in different areas, which can cause cracks and fracture of the sintered body. Third, there is the problem of adaptability of sintering processes, and there are currently few specific processes for preparing pure manganese targets using Joule heating furnaces. Fourth, manganese undergoes a carbon migration reaction with graphite at high temperatures, forming a brittle Mn3C phase contamination layer (up to 50 μm thick), which seriously reduces the purity of the target material. Fifth, manganese has a high self-diffusion activation energy (about 230 kJ / mol), which makes it difficult to complete sufficient bulk diffusion and grain boundary migration in a very short time, resulting in difficulty in spheroidizing residual pores and forming irregular closed pores. Insufficient grain boundary purification leads to the enrichment of impurity elements at the grain boundaries. The phase transformation process is incomplete, resulting in non-equilibrium metastable phases. These factors combined lead to insufficient density (<95%) and deterioration of mechanical properties in the sintered body.

[0030] This invention employs segmented current-controlled heating, two-stage pre-pressing + four-stage gradient pressing (utilizing pre-pressing, low-pressure degassing, medium-pressure densification, and high-pressure sintering), and two-stage cooling (avoiding cracking of the target material due to phase transformation shrinkage differences and rapid cooling thermal stress). By precisely controlling the temperature, time, and stress sensitivity of each stage, it improves the uniformity of sintering temperature, the consistency of pressure applied during pressing, and the effectiveness of releasing internal stress before and after heating. As a result, manganese targets are prepared by sintering at low temperatures and with short sintering times in a short process, improving the efficiency, yield, and yield of mass production.

[0031] (5) Manganese sputtering targets have high requirements for impurity content. This invention applies a vacuum environment during the sintering process, evacuating the Joule heating sintering furnace to a vacuum level less than 8 × 10⁻⁶. -3 At Pa, oxygen and nitrogen in the air are removed, avoiding the influence of impurities such as oxygen and nitrogen in the air on the purity of metallic manganese; moreover, the higher the vacuum degree, the higher the purity of the manganese obtained, while the amount of manganese volatilization is very small due to rapid heating and only the local temperature rise at the contact point of powder particles.

[0032] (6) This invention is suitable for manufacturing target materials with a product diameter of no more than 150 mm and a thickness of 2 to 50 mm. The resulting product has a density of more than 95% and a hardness of more than 140 HV. It can achieve near-net-shape forming in one sintering, and the sintering process only takes tens of minutes. The production cycle is short, the cost is low, and it is suitable for mass production.

[0033] In summary, this invention offers advantages such as fewer production processes, shorter production cycles, lower heating temperatures, and higher density. It leverages the complex allotropic transformations of manganese in the solid state, utilizing the critical transformation temperatures of manganese with different crystal structures and the characteristics of the Joule heating furnace. Segmented current-controlled heating improves sintering density. By utilizing the coupling relationship between the pressure transition point and the temperature phase transition points of manganese with different crystal structures, a two-stage pre-pressing and four-stage gradient pressure strategy—pre-pressing, low-pressure degassing, medium-pressure densification, and high-pressure sintering—is implemented, achieving low-temperature sintering. A two-stage cooling system after sintering avoids stress and cracking during cooling. Precise control of the temperature and time at each stage avoids the need for high heating temperatures and long holding times. Overall, this invention simplifies the production process, effectively and gradually releases internal stress at different temperatures, reduces porosity, and prevents sintering cracking. Optimizing the sintering atmosphere at each stage avoids the impact of impurities such as oxygen in the air on the purity of the sintered manganese target, achieving the goal of producing high-purity manganese targets with low energy consumption, high efficiency, and high quality. Attached Figure Description

[0034] The present invention will be described in detail below with reference to the accompanying drawings and examples. The advantages and implementation methods of the present invention will become more apparent from this description. The accompanying drawings are for illustrative purposes only and do not constitute any limitation on the present invention. In the accompanying drawings:

[0035] Figure 1 This is an X-ray diffraction pattern of the surface of the manganese target material obtained in Example 2 of the present invention.

[0036] Figure 2 This is a Vickers hardness test diagram of the manganese target surface obtained in Example 3 of the present invention.

[0037] Figure 3 Scanning electron microscope image of the surface of the manganese target material obtained in Example 4 of this invention. Detailed Implementation

[0038] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the preferred embodiments.

[0039] Example 1

[0040] Preparation of Φ30mm×2mm high-purity manganese target material:

[0041] S1. Prepare the raw material powder:

[0042] Electrolytic manganese powder is used as the sintering raw material. The powder particle size is 300 mesh. According to the product specifications (Φ30mm×2mm), 10.3g of electrolytic manganese powder is weighed using a balance. Then, the electrolytic manganese powder is placed in a stainless steel pan and then placed in a vacuum drying oven. After the vacuum degree is ≤0.5Pa at room temperature, the temperature is raised and dried at 100℃ for 2 hours to remove the moisture. This completes the preparation of the raw material powder.

[0043] The mass percentage of each element in the electrolytic manganese powder was tested using a Plasma 2000 inductively coupled plasma atomic emission spectrometer combined with a CS-2800 carbon-sulfur analyzer and an ONH3000 oxygen-nitrogen-hydrogen analyzer. The Fe content was 0.015%, S content was 0.017%, P content was 0.0016%, C content was 0.006%, Si content was 0.001%, O content was 0.18%, Se content was 0.03%, and Mn content was higher than 99.74%.

[0044] S2, Loading:

[0045] Select a suitable graphite mold (inner diameter Φ30mm, outer diameter Φ80mm, height 60mm) based on the product size Φ30mm×2mm, and make graphite paper for sintering according to the mold cavity size.

[0046] First, cover the inner wall of the graphite mold cavity and the surface of the lower pressure head or pad with graphite paper to ensure that the graphite mold and manganese powder do not come into direct contact. Then, pour the raw material powder prepared in step S1 into the graphite mold, place a layer of graphite paper on top of the raw material powder, cover the outside of the graphite mold with a layer of heat-insulating asbestos felt, and then insert the upper pressure head into the mold cavity. After placing the loaded graphite mold into the Joule heating sintering furnace, apply a pre-pressure of 8 MPa, close the furnace door, and start evacuating the Joule heating sintering furnace to complete the loading.

[0047] The graphite paper has a thickness of 0.1 mm, a carbon content of over 99%, a tensile strength of ≥4.1 MPa, a sulfur content of ≤300 ppm, and a chlorine content of ≤35 ppm.

[0048] The asbestos felt is a high-temperature asbestos felt (temperature resistant above 1000℃) with a thickness of 7mm. The size of the asbestos felt is determined according to the size of the outer surface of the sintering mold. The surface area of ​​the unfolded asbestos felt needs to be larger than the outer surface area of ​​the mold. The length and width of the asbestos felt are 3mm higher than the outer dimensions of the graphite mold to ensure complete coverage of the outer surface of the graphite mold.

[0049] Both the upper and lower pressure heads are made of graphite and have a pressure resistance of over 90 MPa.

[0050] S3, Sintering:

[0051] When the vacuum degree inside the Joule heating sintering furnace is less than 8×10 -3 After Pa, the temperature is raised, with the pre-pressure reduced to 5 MPa at the beginning of the heating process, and the heating rate at 60 °C / min. When the temperature reaches 300 °C, the heating rate is reduced to 30 °C / min. From the initial temperature rise to 420 °C to the sintering temperature, pressure is applied four times (at 450 °C, 480 °C, 510 °C, and 540 °C), increasing the pressure by 5 MPa each time, holding the pressure for 30 seconds, and then increasing it again, gradually increasing the pressure to 25 MPa. After heating to 500 °C, the temperature is held for 100 seconds, and then the temperature is raised to the sintering temperature (540 °C) at a rate of 30 °C / min, and held for another 500 seconds. After the holding period, the pressure is completely released at once, and the temperature is lowered from the sintering temperature to 350 °C at a rate of 30 °C / min, and then lowered to below 100 °C at a rate of 50 °C / s. Throughout the cooling process, the vacuum level is maintained at a level better than 10. -2 Pa, sintering is complete.

[0052] S4. Unloading and Inspection:

[0053] After completing the sintering in step S3, the vacuum is closed and the gas is released. The Joule heating sintering furnace door is opened and the graphite mold is removed. The graphite mold is pressed into a manganese target product using a press. The graphite on the surface of the manganese target product is removed by sanding with fine sandpaper. The chemical composition, density and hardness of the manganese target product are measured. After the analysis is qualified, it is packaged and stored to complete the preparation of the manganese target.

[0054] The mass percentage of elements in the manganese target was tested using a Plasma 2000 inductively coupled plasma atomic emission spectrometer combined with a CS-2800 carbon-sulfur analyzer and an ONH3000 oxygen-nitrogen-hydrogen analyzer. The results showed that the Fe content was 0.015%, the S content was 0.017%, the P content was 0.0016%, the C content was 0.006%, the Si content was 0.001%, the O content was 0.13%, the Se content was 0.025%, and the Mn content was higher than 99.80%.

[0055] The final high-purity manganese target material has dimensions of Φ30mm × 2mm. The density of the manganese target material, measured using a DJ-600Te digital display solid-powder integrated density meter, is 7.20 g / cm³. 3 It reaches the theoretical density (7.474 g / cm³). 3 It has 96.3% of the properties and a hardness of 140HV.

[0056] Example 2

[0057] Preparation of Φ100mm×50mm high-purity manganese target:

[0058] S1. Prepare the raw material powder:

[0059] Electrolytic manganese powder, the same as in Example 1, was used as the sintering raw material. The powder particle size was 400 mesh. According to the product specifications (Φ100mm×50mm), 2863g of electrolytic manganese powder was weighed using a balance. Then, the electrolytic manganese powder was placed in a stainless steel pan and then placed in a vacuum drying oven. After the vacuum degree was ≤0.5Pa at room temperature, the temperature was raised and dried at 130℃ for 6 hours to remove the moisture. This completed the preparation of the raw material powder.

[0060] The mass percentage of each element in the electrolytic manganese powder was tested using a Plasma 2000 inductively coupled plasma atomic emission spectrometer combined with a CS-2800 carbon-sulfur analyzer and an ONH3000 oxygen-nitrogen-hydrogen analyzer. The Fe content was 0.015%, S content was 0.017%, P content was 0.0016%, C content was 0.006%, Si content was 0.001%, O content was 0.18%, Se content was 0.03%, and Mn content was higher than 99.74%.

[0061] S2, Loading:

[0062] Select a suitable graphite mold (inner diameter Φ100mm, outer diameter Φ160mm, height 130mm) based on the product size Φ100mm×50mm, and make graphite paper for sintering according to the mold cavity size.

[0063] First, cover the inner wall of the graphite mold cavity and the surface of the lower pressure head or pad with graphite paper to ensure that the graphite mold and manganese powder do not come into direct contact. Then, pour the raw material powder prepared in step S1 into the graphite mold, place two layers of graphite paper on top of the raw material powder, cover the outside of the graphite mold with a layer of heat-insulating asbestos felt, and then insert the upper pressure head into the mold cavity. After placing the loaded graphite mold into the Joule heating sintering furnace, apply a pre-pressure of 14 MPa, close the furnace door, and start evacuating the Joule heating sintering furnace to complete the loading.

[0064] The graphite paper has a thickness of 0.1 mm, a carbon content of over 99%, a tensile strength of ≥4.1 MPa, a sulfur content of ≤300 ppm, and a chlorine content of ≤35 ppm.

[0065] The asbestos felt is a high-temperature asbestos felt (temperature resistant above 1000℃) with a thickness of 8mm. The size of the asbestos felt is determined according to the size of the outer surface of the sintering mold. The surface area of ​​the unfolded asbestos felt needs to be larger than the outer surface area of ​​the mold. The length and width of the asbestos felt are 7mm higher than the outer dimensions of the graphite mold to ensure complete coverage of the outer surface of the graphite mold.

[0066] Both the upper and lower pressure heads are made of graphite and have a pressure resistance of over 90 MPa.

[0067] S3, Sintering:

[0068] When the vacuum degree inside the Joule heating sintering furnace is less than 5×10 -3 After Pa, the temperature is raised, with the pre-pressure reduced to 8 MPa at the beginning of the heating process, and the heating rate at 30 °C / min. When the temperature reaches 300 °C, the heating rate is reduced to 15 °C / min. From the initial temperature of 420 °C to the sintering temperature, pressure is applied four times (at 465 °C, 510 °C, 555 °C, and 600 °C), increasing the pressure by 10 MPa each time, holding the pressure for 30 seconds, and then increasing it again, gradually increasing the pressure to 48 MPa. After heating to 500 °C, the temperature is held for 200 seconds, and then the temperature is raised to the sintering temperature (600 °C) at a rate of 15 °C / min, and held for another 800 seconds. After the holding period, the pressure is completely released at once, and the temperature is lowered from the sintering temperature to 350 °C at a rate of 15 °C / min, and then lowered to below 100 °C at a rate of 30 °C / s. Throughout the cooling process, the vacuum level is maintained at a level better than 10. -2 Pa, sintering is complete.

[0069] S4. Unloading and Inspection:

[0070] After completing the sintering in step S3, the vacuum is closed and the gas is released. The Joule heating sintering furnace door is opened and the graphite mold is removed. The graphite mold is pressed into a manganese target product using a press. The graphite on the surface of the manganese target product is removed by sanding with fine sandpaper. The chemical composition, density and hardness of the manganese target product are measured. After the analysis is qualified, it is packaged and stored to complete the preparation of the manganese target.

[0071] The mass percentage of elements in the manganese target was tested using a Plasma 2000 inductively coupled plasma atomic emission spectrometer combined with a CS-2800 carbon-sulfur analyzer and an ONH3000 oxygen-nitrogen-hydrogen analyzer. The results showed that the Fe content was 0.015%, the S content was 0.017%, the P content was 0.0016%, the C content was 0.006%, the Si content was 0.001%, the O content was 0.10%, the Se content was 0.024%, and the Mn content was higher than 99.83%.

[0072] The final high-purity manganese target material has dimensions of Φ100mm × 50mm. Using a DJ-600Te digital display solid-powder integrated density meter, the density of the manganese target material was measured to be 7.28 g / cm³. 3 It reaches the theoretical density (7.474 g / cm³). 3 It has 97.4% of the properties of ) and a hardness of 185HV.

[0073] like Figure 1 As shown, only the diffraction peaks of the α-Mn phase were obtained in the figure; no other phases were found. The α-Mn phase has a space group of [missing information]. A cubic structure.

[0074] Example 3

[0075] Preparation of Φ150mm×20mm high-purity manganese target:

[0076] S1. Prepare the raw material powder:

[0077] Electrolytic manganese powder, as in Example 1, was used as the sintering raw material. The powder particle size was 200 mesh (20%), 300 mesh (40%), and 400 mesh (40%). According to the product specifications (Φ150mm×20mm), 2588g of electrolytic manganese powder was weighed using a balance. Then, the electrolytic manganese powder was placed in a stainless steel pan and then placed in a vacuum drying oven. After the vacuum degree was ≤0.5Pa at room temperature, the temperature was raised and dried at 120℃ for 5 hours to remove the moisture, thus completing the preparation of the raw material powder.

[0078] The mass percentage of each element in the electrolytic manganese powder was tested using a Plasma 2000 inductively coupled plasma atomic emission spectrometer combined with a CS-2800 carbon-sulfur analyzer and an ONH3000 oxygen-nitrogen-hydrogen analyzer. The Fe content was 0.015%, S content was 0.017%, P content was 0.0016%, C content was 0.006%, Si content was 0.001%, O content was 0.18%, Se content was 0.03%, and Mn content was higher than 99.74%.

[0079] S2, Loading:

[0080] Select a suitable graphite mold (inner diameter Φ150mm, outer diameter Φ220mm, height 70mm) based on the product size Φ150mm×20mm, and make graphite paper for sintering according to the mold cavity size.

[0081] First, cover the inner wall of the graphite mold cavity and the surface of the lower pressure head or pad with graphite paper to ensure that the graphite mold and manganese powder do not come into direct contact. Then, pour the raw material powder prepared in step S1 into the graphite mold, place a layer of graphite paper on top of the raw material powder, cover the outside of the graphite mold with a layer of heat-insulating asbestos felt, and then insert the upper pressure head into the mold cavity. After placing the loaded graphite mold into the Joule heating sintering furnace, apply a pre-pressure of 14 MPa, close the furnace door, and start evacuating the Joule heating sintering furnace to complete the loading.

[0082] The graphite paper has a thickness of 0.2 mm, a carbon content of over 99%, a tensile strength of ≥4.0 MPa, a sulfur content of ≤300 ppm, and a chlorine content of ≤35 ppm.

[0083] The asbestos felt is a high-temperature asbestos felt (temperature resistant above 1000℃) with a thickness of 7mm. The size of the asbestos felt is determined according to the size of the outer surface of the sintering mold. The surface area of ​​the unfolded asbestos felt needs to be larger than the outer surface area of ​​the mold. The length and width of the asbestos felt are 5mm higher than the outer dimensions of the graphite mold to ensure complete coverage of the outer surface of the graphite mold.

[0084] Both the upper and lower pressure heads are made of graphite and have a pressure resistance of over 90 MPa.

[0085] S3, Sintering:

[0086] When the vacuum degree inside the Joule heating sintering furnace is less than 5×10 -3After Pa, the temperature is raised, with the pre-pressure reduced to 8 MPa at the beginning of the heating process, and the heating rate at 40 °C / min. When the temperature reaches 300 °C, the heating rate is reduced to 20 °C / min. From the initial temperature rise to 420 °C to the sintering temperature, pressure is applied four times (at 460 °C, 500 °C, 540 °C, and 580 °C), increasing the pressure by 7 MPa each time, holding the pressure for 30 seconds, and then increasing it again, gradually increasing the pressure to 36 MPa. After heating to 500 °C, the temperature is held for 150 seconds, and then the temperature is raised to the sintering temperature (580 °C) at a rate of 20 °C / min, and held for another 600 seconds. After the holding period, the pressure is completely released at once, and the temperature is lowered from the sintering temperature to 350 °C at a rate of 20 °C / min, and then lowered to below 100 °C at a rate of 40 °C / s. Throughout the cooling process, the vacuum level is maintained at a level better than 10. -2 Pa, sintering is complete.

[0087] S4. Unloading and Inspection:

[0088] After completing the sintering in step S3, the vacuum is closed and the gas is released. The Joule heating sintering furnace door is opened and the graphite mold is removed. The graphite mold is pressed into a manganese target product using a press. The graphite on the surface of the manganese target product is removed by sanding with fine sandpaper. The chemical composition, density and hardness of the manganese target product are measured. After the analysis is qualified, it is packaged and stored to complete the preparation of the manganese target.

[0089] The mass percentage of elements in the manganese target was tested using a Plasma 2000 inductively coupled plasma atomic emission spectrometer combined with a CS-2800 carbon-sulfur analyzer and an ONH3000 oxygen-nitrogen-hydrogen analyzer. The results showed that the Fe content was 0.015%, the S content was 0.017%, the P content was 0.0016%, the C content was 0.006%, the Si content was 0.001%, the O content was 0.16%, the Se content was 0.025%, and the Mn content was higher than 99.78%.

[0090] The final high-purity manganese target material has dimensions of Φ150mm × 20mm. The density of the manganese target material, measured using a DJ-600Te digital display solid-powder integrated density meter, is 7.32 g / cm³. 3 It reaches the theoretical density (7.474 g / cm³). 3 98.0% of the content, with a hardness of 209HV.

[0091] like Figure 2 As shown, under the test conditions of 1.0 kgf, the hardness of the high-purity manganese target material finally obtained in Example 3 was 209 HV.

[0092] Example 4

[0093] Preparation of Φ78mm×3.5mm high-purity manganese sputtering target:

[0094] S1. Prepare the raw material powder:

[0095] Electrolytic manganese powder, as in Example 1, was used as the sintering raw material. The powder particle size was 50% 300 mesh and 50% 400 mesh. According to the product specifications (Φ78mm×3.5mm), 121g of electrolytic manganese powder was weighed using a balance. Then, the electrolytic manganese powder was placed in a stainless steel pan and then placed in a vacuum drying oven. After the vacuum degree was ≤0.5Pa at room temperature, the temperature was raised and dried at 120℃ for 4 hours to remove the moisture, thus completing the preparation of the raw material powder.

[0096] The mass percentage of each element in the electrolytic manganese powder was tested using a Plasma 2000 inductively coupled plasma atomic emission spectrometer combined with a CS-2800 carbon-sulfur analyzer and an ONH3000 oxygen-nitrogen-hydrogen analyzer. The Fe content was 0.015%, S content was 0.017%, P content was 0.0016%, C content was 0.006%, Si content was 0.001%, O content was 0.18%, Se content was 0.03%, and Mn content was higher than 99.74%.

[0097] S2, Loading:

[0098] Select a suitable graphite mold (inner diameter Φ78mm, outer diameter Φ150mm, height 40mm) based on the product size Φ78mm×3.5mm, and make graphite paper for sintering according to the inner cavity size of the mold.

[0099] First, cover the inner wall of the graphite mold cavity and the surface of the lower pressure head or pad with graphite paper to ensure that the graphite mold and manganese powder do not come into direct contact. Then, pour the raw material powder prepared in step S1 into the graphite mold, place a layer of graphite paper on top of the raw material powder, cover the outside of the graphite mold with a layer of heat-insulating asbestos felt, and then insert the upper pressure head into the mold cavity. After placing the loaded graphite mold into the Joule heating sintering furnace, apply a pre-pressure of 12 MPa, close the furnace door, and start evacuating the Joule heating sintering furnace to complete the loading.

[0100] The graphite paper has a thickness of 0.1 mm, a carbon content of over 99%, a tensile strength of ≥4.1 MPa, a sulfur content of ≤300 ppm, and a chlorine content of ≤35 ppm.

[0101] The asbestos felt is a high-temperature asbestos felt (temperature resistant above 1000℃) with a thickness of 7mm. The size of the asbestos felt is determined according to the size of the outer surface of the sintering mold. The surface area of ​​the unfolded asbestos felt needs to be larger than the outer surface area of ​​the mold. The length and width of the asbestos felt are 5mm higher than the outer dimensions of the graphite mold to ensure complete coverage of the outer surface of the graphite mold.

[0102] Both the upper and lower pressure heads are made of graphite and have a pressure resistance of over 90 MPa.

[0103] S3, Sintering:

[0104] When the vacuum degree inside the Joule heating sintering furnace is less than 6×10 -3 After Pa, the temperature is raised, with the pre-pressure reduced to 8 MPa at the beginning of the heating process, and the heating rate at 50 °C / min. When the temperature reaches 300 °C, the heating rate is reduced to 20 °C / min. From the initial temperature rise to 420 °C to the sintering temperature, pressure is applied four times (at 455 °C, 490 °C, 525 °C, and 560 °C), increasing the pressure by 6 MPa each time, holding the pressure for 30 seconds, and then increasing it again, gradually increasing the pressure to 32 MPa. After heating to 500 °C, the temperature is held for 180 seconds, and then the temperature is raised to the sintering temperature (560 °C) at a rate of 20 °C / min, and held for another 700 seconds. After the holding period, the pressure is completely released at once, and the temperature is lowered from the sintering temperature to 350 °C at a rate of 18 °C / min, and then lowered to below 100 °C at a rate of 35 °C / s. Throughout the cooling process, the vacuum level is maintained at a level better than 10. -2 Pa, sintering is complete.

[0105] S4. Unloading and Inspection:

[0106] After completing the sintering in step S3, the vacuum is closed and the gas is released. The Joule heating sintering furnace door is opened and the graphite mold is removed. The graphite mold is pressed into a manganese target product using a press. The graphite on the surface of the manganese target product is removed by sanding with fine sandpaper. The chemical composition, density and hardness of the manganese target product are measured. After the analysis is qualified, it is packaged and stored to complete the preparation of the manganese target.

[0107] The mass percentage of elements in the manganese target was tested using a Plasma 2000 inductively coupled plasma atomic emission spectrometer combined with a CS-2800 carbon-sulfur analyzer and an ONH3000 oxygen-nitrogen-hydrogen analyzer. The results showed that the Fe content was 0.015%, the S content was 0.017%, the P content was 0.0016%, the C content was 0.006%, the Si content was 0.001%, the O content was 0.15%, the Se content was 0.025%, and the Mn content was higher than 99.78%.

[0108] The final high-purity manganese target material has dimensions of Φ78mm × 3.5mm. Using a DJ-600Te digital display solid-powder integrated density meter, the density of the manganese target material was measured to be 7.23 g / cm³. 3 It reaches the theoretical density (7.474 g / cm³). 3 It has 96.8% of the properties and a hardness of 195HV.

[0109] like Figure 3 As shown, the high-purity manganese target material finally obtained in Example 4 has a dense overall surface and uniform structure.

[0110] The embodiments of the present invention have been described in detail above, but the content described is only a preferred embodiment of the present invention and should not be considered as limiting the scope of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the scope of the present invention.

Claims

1. A method for preparing a high-purity manganese target, characterized in that: Includes the following steps: S1. Prepare the raw material powder: Weigh the required mass of manganese powder as sintering raw material, dry the manganese powder, and complete the preparation of the raw material powder. S2, Loading: Pour the raw material powder prepared in step S1 into the graphite mold. After the graphite mold is placed in the Joule heating sintering furnace, apply a pre-pressure of 8-14 MPa, close the furnace door, and start vacuuming the Joule heating sintering furnace to complete the loading. S3, Sintering: When the vacuum degree inside the Joule heating sintering furnace is less than 8×10 -3 After reaching Pa, the temperature is raised, with the pre-pressure reduced to 5–8 MPa at the beginning of the heating process, and the heating rate at 30–60 °C / min. When the temperature reaches 300 °C, the heating rate is reduced to 30–15 °C / min. From the initial temperature rise to 420 °C to the sintering temperature, pressure is applied in four stages, increasing by 5–10 MPa each time, maintaining the pressure for 30 seconds, and then increasing it again, gradually increasing the pressure to 25–48 MPa. After heating to 500 °C, the temperature is held for 100–200 seconds, and then the temperature is raised to the sintering temperature at a rate of 15–30 °C / min, and held again for 500–800 seconds. After the holding period, the pressure is completely released at once, and the temperature is lowered from the sintering temperature to 350 °C at a rate of 30–15 °C / min, and then lowered to below 100 °C at a rate of 50–30 °C / s. Throughout the cooling process, the vacuum level is maintained at a level better than 10. -2 Pa, sintering is completed; S4, Out of the oven: After completing the sintering in step S3, the vacuum is closed and the gas is released. The furnace door of the Joule heating sintering furnace is opened and the graphite mold is removed. The manganese target product is pressed out from the graphite mold, and the graphite on the surface of the manganese target product is ground off to complete the preparation of the manganese target.

2. The method for preparing high-purity manganese target material according to claim 1, characterized in that: In step S1, during drying, manganese powder is placed in a stainless steel tray and then placed in a vacuum drying oven. After the vacuum degree is ≤0.5Pa at room temperature, the temperature is raised and dried at 100-130℃ for 2-6 hours.

3. The method for preparing high-purity manganese target material according to claim 1, characterized in that: In step S1, the purity of the manganese powder is not less than 99.7%, and the content of Fe in the manganese powder is ≤0.02%, S≤0.02%, P≤0.01%, C≤0.02%, Si≤0.01%, O≤0.2%, and the particle size of the manganese powder is 200-400 mesh.

4. The method for preparing high-purity manganese target material according to claim 1, characterized in that: In step S2, the specific process of loading the material is as follows: First, cover the inner wall of the graphite mold cavity and the surface of the lower pressure head or pad with graphite paper; then pour the raw material powder prepared in step S1 into the graphite mold, then place 1 to 2 layers of graphite paper on top of the raw material powder, cover the outside of the graphite mold with a layer of heat-insulating asbestos felt, and then insert the upper pressure head into the mold cavity; then place the loaded graphite mold into the Joule heating sintering furnace.

5. The method for preparing high-purity manganese target material according to claim 4, characterized in that: In step S2, the graphite paper has a thickness of 0.1 to 0.2 mm, a carbon content of more than 99%, a tensile strength of ≥4.0 MPa, a sulfur content of ≤300 ppm, and a chlorine content of ≤35 ppm; the asbestos felt is a high-temperature asbestos felt with a thickness of ≥7 mm, and the length and width of the asbestos felt are 3 to 7 mm higher than the outer dimensions of the graphite mold.

6. The method for preparing high-purity manganese target material according to claim 1, characterized in that: In step S3, the sintering temperature is 540–600°C.

7. The method for preparing high-purity manganese target material according to claim 1, characterized in that: In step S4, after the product is taken out of the furnace, it needs to be tested. After the graphite on the surface of the manganese target material is removed by sanding with fine sandpaper, the chemical composition, density and hardness of the manganese target material are measured. After the analysis is qualified, it is packaged and put into storage.

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