Preparation method of high-purity manganese target material

Abstract

The invention relates to a preparation method of a high-purity manganese target material, which belongs to the technical field of metallurgy, and comprises the following steps: firstly, drying manganese powder, then pouring the manganese powder into a graphite mold, and putting the graphite mold into a Joule hot sintering furnace for sintering, during sintering, a strategy of two-stage prepressing and four-stage gradient pressing of prepressing forming, low-pressure degassing, medium-pressure densification and high-pressure sintering is implemented, and low-temperature sintering is realized; through two-stage cooling after sintering, stress and cracking in the cooling process are avoided; by accurately controlling the temperature and time of each stage, the defects that high heating temperature and long heat preservation time are needed are overcome. The production process is integrally simplified, the internal stress is controlled to be effectively and gradually released at different temperatures, the porosity is reduced, and sintering cracking is avoided; by optimizing the sintering atmosphere of each stage, the influence of impurities such as oxygen in the air on the purity of the sintered manganese target material is avoided, and the purpose of preparing the high-purity manganese target material with low energy consumption, high efficiency and high quality is achieved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of metallurgy, and particularly relates to a preparation method of high-purity manganese target material. BACKGROUND

[0002] In the microelectronics industry, manganese target material is often used to make various integrated circuits and microchips. In the optoelectronics industry, manganese target material is often used to make thin film materials for optoelectronic devices, such as LEDs, solar cells, etc. In the magnetic recording industry, manganese target material is often used to make magnetic thin films for hard disk drives. Manganese target material plays an important role in many technology fields due to its unique characteristics.

[0003] Most of the disclosed patents are only related to the preparation of manganese alloy target material. CN115338374A discloses a preparation method of ultra-high purity copper-manganese ingot for semiconductor target material, which mixes copper liquid with manganese raw material through multiple pressure adjustment and temperature rising processes, obtains ultra-high purity copper-manganese alloy liquid, and then performs casting, effectively solving the element segregation problem in the production process of copper-manganese alloy target material. However, this scheme needs multiple pressure adjustment and temperature rising, and the process is relatively complex, and high-precision melting equipment is required, which also has high requirements on the equipment. CN106399954A discloses a processing method of long-life copper-manganese alloy target material, which uses conventional thermal mechanical processing method to process copper-manganese alloy ingot to obtain raw material; and uses stir friction processing to refine the grain of the raw material, thereby improving the service life of the target material. However, this method is mainly suitable for copper-manganese alloy, and is not suitable for other types of target material, and its processing efficiency is also relatively low. The technical solutions of CN115338374A and CN106399954A do not take appropriate protection measures during sintering, which may cause oxidation on the surface or inside of the target material, thereby increasing the oxygen content. CN117758087A discloses a casting ingot melting method of ultra-high purity copper-manganese alloy sputtering target material, which melts and refines through a vacuum suspension melting furnace, thereby solving the problem of excessive impurity content in the traditional method. However, due to the complex process, the preparation methods of these patents are limited in production efficiency.

[0004] In the preparation of manganese metal, CN113862495A discloses a method for preparing high-purity manganese by vacuum distillation, sandblasting and pickling. CN115948769A discloses a method for preparing high-purity manganese metal by electrolysis, but this technology uses manganese sulfate for electrolysis to prepare manganese, and the prepared manganese contains a large amount of sulfur and oxygen impurities, reducing the quality of the product. CN105200453A discloses a method for preparing high-purity manganese by electrolysis, which uses secondary electrolytic refining to prepare high-purity manganese, deeply removes impurities, and improves the purity of manganese products, but the process has high energy consumption, causes serious environmental pollution, and the process flow is relatively complex, and the gas impurities cannot be controlled. CN103114303A discloses a deep purification process method and additive for high-purity selenium-free electrolytic manganese production. This process uses additives to purify the electrolyte and then prepares manganese by electrolysis, which requires precise control of the content of the additive, the process flow is complex, the additive itself introduces new impurities, and the cost is also relatively high, which may also cause some pollution to the environment.

[0005] Key, the preparation of high-purity manganese target material faces a series of technical problems caused by the special properties of manganese element. As a transition metal, manganese has the characteristics of high chemical activity, low melting point (1246℃) and high vapor pressure, and is easy to oxidize and volatilize during high-temperature treatment. At the same time, manganese has complex polymorphic transformation (alpha, beta, gamma, and delta four crystal forms) in solid state, and significant volume change during phase transition, resulting in cracks and deformation of the sintered body. These characteristics make the preparation of high-purity manganese target material more difficult than general metal target material, especially in densification control and microstructure uniformity. Moreover, the strong affinity of manganese and oxygen leads to serious oxide inclusion problem. In terms of densification, conventional vacuum sintering is difficult to achieve full diffusion creep due to low thermal efficiency and insufficient upper limit of temperature, resulting in a relative density generally lower than 95%, and producing open and closed hole defects. The above problems will cause particle pollution in the sputtering process, increase the resistivity of the thin film, uneven sputtering rate, thin film thickness fluctuation, reduce the utilization rate of the target material, shorten the service life, and cause arc discharge in the sputtering process, resulting in low yield.

[0006] So far, there is still a lack of corresponding preparation technology for efficiently and high-quality preparing high-purity manganese target material at home and abroad. SUMMARY

[0007] The technical problem to be solved by the present application is to provide a preparation method for preparing high-purity manganese target material at low cost and high quality by using a low-temperature sintering furnace.

[0008] To solve the above technical problems, the technical scheme adopted by the present application is as follows: a preparation method of high-purity manganese target material, comprising the following steps:

[0009] S1, preparing raw material powder:

[0010] Manganese powder as sintering raw material, according to product specifications, the required mass of manganese powder is weighed by balance, then the manganese powder is put into a stainless steel tray, and then put into a vacuum drying oven. After the vacuum degree is less than or equal to 0.5 Pa at room temperature, the temperature is started to be raised and dried at 100-130 ℃ for 2-6 h to remove the moisture therein, and the preparation of the raw material powder is completed.

[0011] Further, the purity of the manganese powder is not less than 99.7%, and Fe≤0.02%, S≤0.02%, P≤0.01%, C≤0.02%, Si≤0.01%, O≤0.2%, and the powder particle size is 200-400 mesh.

[0012] S2, charging:

[0013] According to the size of the product, a graphite mold of appropriate specification is selected, and a graphite paper for sintering is made according to the size of the inner cavity of the mold.

[0014] First, the inner wall of the inner cavity of the graphite mold and the surface of the lower head or the base plate are covered with graphite paper to ensure that the graphite mold does not directly contact the manganese powder; then the raw material powder prepared in step S1 is poured into the graphite mold, and 1-2 layers of graphite paper are placed on top of the raw material powder. A layer of asbestos felt for heat preservation is wrapped outside the graphite mold, and the upper head is inserted into the mold cavity; the graphite mold with the charge is placed into the joule heat sintering furnace, and a pre-pressure of 8-14 MPa is applied. The door of the furnace is closed, and the joule heat sintering furnace is started to be vacuumized, and the charging is completed.

[0015] Further, the thickness of the graphite paper is 0.1-0.2 mm, the carbon content is higher than 99%, the tensile strength is greater than or equal to 4.0 MPa, the sulfur content is less than or equal to 300 ppm, and the chlorine content is less than or equal to 35 ppm.

[0016] Further, the asbestos felt is a high-temperature asbestos felt (resistant to temperature above 1000 ℃), and the thickness is greater than or equal to 7 mm. 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 asbestos felt needs to be greater than the area of the outer surface of the mold, and the length and width of the asbestos felt are higher than the outer dimension of the graphite mold by 3-7 mm to ensure that the outer surface of the graphite mold is completely covered.

[0017] Further, the upper head and the lower head are both made of graphite, and the required pressure resistance is not less than 90 MPa.

[0018] S3, sintering:

[0019] When the vacuum degree in the joule heat sintering furnace is less than 8×10 -3After starting to increase temperature, the pre-pressure is reduced to 5-8 MPa at the beginning of temperature increase, the heating rate is 30-60 DEG C / min, when the temperature reaches 300 DEG C, the heating rate is reduced to 30-15 DEG C / min; the pressure is applied for 4 times from the process of increasing temperature to 420 DEG C to the sintering temperature, the pressure is increased by 5-10 MPa each time, the pressure is maintained for 30 s before re-pressurizing, and the pressure is gradually increased to 25-48 MPa; after heating to 500 DEG C, the temperature is maintained for 100-200 s, then the temperature is increased to the sintering temperature (540-600 DEG C) at a heating rate of 15-30 DEG C / min, and the temperature is maintained for 500-800 s again, after the temperature maintaining is completed, the pressure is all discharged at one time, the temperature is decreased from the sintering temperature to 350 DEG C at a rate of 30-15 DEG C / min, and then the temperature is decreased to below 100 DEG C at a rate of 50-30 DEG C / s, the vacuum degree is maintained to be better than 10 -2 Pa during the temperature decreasing process, and the sintering is completed.

[0020] S4, discharging and detection:

[0021] After the sintering of step S3 is completed, the vacuum is closed and the gas is discharged, the graphite mold is taken out by opening the door of the joule heat sintering furnace; the manganese target product is pressed out by using a press, the graphite on the surface of the manganese target product is polished by using fine sandpaper, and the corresponding chemical composition, density and hardness of the manganese target product are measured, the manganese target product is packaged and stored after analysis and passes, and the preparation of the manganese target material is completed.

[0022] According to the above, the beneficial effects of the present application are:

[0023] (1) The melting point of manganese is 1246 DEG C, and the boiling point is 2061 DEG C, but the saturated vapor pressure of manganese increases exponentially in a high-temperature environment above 1200 DEG C, resulting in a large amount of volatilization of manganese.

[0024] The present application uses a joule heat sintering furnace to sinter and prepare manganese powder, the temperature of the local area of the contact point is sharply increased by using the joule heat effect generated when a large current passes through the powder particles, and the heating temperature of the whole manganese powder is still very low, therefore, the preparation of the manganese target material by using the joule heat sintering furnace has the characteristics of rapid temperature increase and low-temperature sintering, the preparation heating speed is fast, the process is short, the production cost is greatly saved, and it is suitable for batch production.

[0025] (2) Manganese exists in a complex allotrope transformation in a solid state, below 707 DEG C, it is alpha-Mn phase, in the interval of 707 DEG C-1087 DEG C, it is beta-Mn phase, in the interval of 1087 DEG C-1137 DEG C, it is gamma-Mn phase, and above 1137 DEG C, it is delta-Mn phase, during the phase transformation, there is a significant volume change, resulting in cracks and deformation of the sintered body. At the same time, it is difficult for a conventional atmosphere control system to establish dynamic pressure balance when sintering at high temperature, the residual oxygen causes oxidation when the vacuum degree is insufficient, and volatilization is intensified when the vacuum degree is too high.

[0026] The application controls the overall heating temperature in the low-temperature stage of the alpha phase zone, avoids phase transition in the sintering process of the powder particles, thereby avoiding the defects of sintered body fracture caused by cracks, and also solving the problems of manganese evaporation and brittle layer formation caused by the reaction between manganese and graphite mold at high temperature.

[0027] (3) The existing process for preparing manganese target material generally relies on a multi-step complex process, such as pre-pressing, sintering, hot isostatic pressing, and heat treatment, which not only increases the production cost, but also introduces secondary pollution risk and reduces the yield. Although the ingot produced by melting and then cutting can also manufacture target material, due to the fact that the saturation vapor pressure of manganese increases exponentially when the temperature exceeds 1200℃, the material loss rate is as high as 15~20%, and the volatilization in the furnace condenses and pollutes the heat generator and the heat insulation layer, forming a vicious cycle.

[0028] The low-temperature sintering of the application utilizes the high self-diffusion coefficient of alpha-Mn to promote the formation of sintered powder neck, utilizes the temperature sharply rising characteristics of the local area of the powder particle contact points to match the medium diffusion capacity of gamma-Mn to realize pore elimination, and utilizes the surface energy reduction in the delta-Mn phase zone to complete the grain boundary optimization, thereby improving the density of the manganese target material to be better than 95%.

[0029] (4) There are many technical bottlenecks in the rapid preparation of manganese target material by using a Joule heat sintering furnace. First, because of the fast heating speed, the heat distribution in the furnace is uneven, the temperature difference of different heating points is formed, thereby the sintering uniformity is poor and defects such as uneven structure, color spots and color difference, hardness soft spots, and pores are formed; second, the fast heating speed also causes large thermal stress difference in different regions and forms cracks and causes the sintered body to break; third, the sintering process adaptability problem, there are few specific processes for preparing pure manganese target material by using a Joule heat sintering furnace; fourth, manganese reacts with graphite at high temperature to form a brittle Mn3C phase pollution layer (thickness up to 50μm), which seriously reduces the purity of the target material; fifth, the self-diffusion activation energy of manganese is high (about 230kJ / mol), it is difficult to complete full body diffusion and grain boundary migration in a very short time, resulting in difficulty in residual pore spheroidization, forming irregular closed pores; the grain boundary is not purified enough, impurity elements are enriched in the grain boundary; the phase transition process is not complete, producing non-equilibrium metastable phase. These factors comprehensively cause the sintered body density to be insufficient (<95%) and the mechanical properties to be deteriorated.

[0030] The present application improves the uniformity of sintering temperature, the consistency of applied pressure in the pressing process, and the effectiveness of internal stress release before and after heating, thereby sintering the manganese target material at a low sintering temperature and a short sintering time, and improving the efficiency, yield and good product rate of batch production.

[0031] (5) The manganese target material has a high requirement for impurity content. The present application applies a vacuum environment to the sintering process, and the Joule heat sintering furnace is vacuumized to a vacuum degree less than 8x10 -3 Pa, and the oxygen and nitrogen in the air are excluded, thereby avoiding the influence of impurities such as oxygen and nitrogen in the air on the purity of the manganese. Moreover, the higher the vacuum degree, the higher the purity of the obtained manganese, and the evaporation of the manganese is very small due to rapid heating and local temperature rise at the contact points of the powder particles.

[0032] (6) The present application is suitable for manufacturing a target material with a diameter not greater than 150 mm and a thickness of 2-50 mm, and the obtained product has a density of more than 95% and a hardness of more than 140 HV, and the near-net forming is realized by one-time sintering, and only dozens of minutes are needed for sintering, thereby shortening the production cycle, reducing the cost, and being suitable for batch production.

[0033] In summary, the present application has the advantages of few production processes, short production cycle, low heating temperature and high density. In combination with the complex polymorphic transformation of manganese in solid state, the critical transformation temperature of manganese with different crystal structures and the characteristics of the Joule heat sintering furnace are utilized, and the sintering density is improved by the segmented current control heating. The coupling relationship between the pressure conversion point and the temperature transformation point of manganese with different crystal structures is utilized, and the two-stage pre-pressing and four-stage gradient pressure strategy of pre-pressing, low-pressure degassing, medium-pressure densification and high-pressure sintering is implemented, thereby realizing low-temperature sintering. The two-stage cooling after sintering is designed, thereby avoiding stress and cracking in the cooling process. The temperature and time of each stage are accurately controlled, thereby avoiding the need for high heating temperature and long holding time. The present application simplifies the production process as a whole, controls the effective step-by-step release of internal stress at different temperatures, reduces the porosity, and avoids sintering cracking. By optimizing the sintering atmosphere of each stage, the influence of impurities such as oxygen in the air on the purity of the sintered manganese target material is avoided, and the purpose of low-energy-consumption, high-efficiency and high-quality preparation of high-purity manganese target material is achieved. BRIEF DESCRIPTION OF DRAWINGS

[0034] The advantages and implementation manners of the present application will be more apparent through the following specific description of the present application by referring to the accompanying drawings, which are only used to explain the present application and do not constitute any limitation to the present application, and in the drawings:

[0035] Figure 1 is the X-ray diffraction pattern of the surface of the manganese target material prepared in Embodiment 2 of the present application.

[0036] Figure 2 is the Vickers hardness test pattern of the surface of the manganese target material prepared in Embodiment 3 of the present application.

[0037] Figure 3 is the scanning electron microscope image of the surface of the manganese target material prepared in Embodiment 4 of the present application. DETAILED DESCRIPTION

[0038] In order for those skilled in the art to better understand the technical solutions of the present application, the present application will be further described in detail below in combination with the best embodiments.

[0039] Embodiment 1

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

[0041] S1, preparation of raw material powder:

[0042] The electrolytic manganese powder is used as the sintering raw material, the powder particle size is 300 mesh, according to the product specification (Φ30mm×2mm), the electrolytic manganese powder 10.3g is weighed by a balance, then the electrolytic manganese powder is placed in a stainless steel tray, and then placed in a vacuum drying oven, after the room temperature vacuum degree is less than or equal to 0.5Pa, the temperature is started to be raised and dried at 100℃ for 2h to remove the water therein, and the preparation of the raw material powder is completed.

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

[0044] S2, loading:

[0045] According to the product size Φ30mm×2mm, a graphite mold of appropriate specification (inner diameter Φ30mm, outer diameter Φ80mm, height 60mm) is selected, and a graphite paper for sintering is made according to the size of the inner cavity of the mold.

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

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

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

[0049] The upper head and the lower head are both made of graphite, with a compressive strength higher than 90 MPa.

[0050] S3, sintering:

[0051] When the vacuum degree in the joule heat sintering furnace is less than 8×10 -3 Pa, start heating. The pre-pressure is reduced to 5 MPa at the beginning of heating, and the heating rate is 60℃ / min. When the temperature reaches 300℃, the heating rate is reduced to 30℃ / min. The pressure is applied 4 times from the start of heating to 420℃ to the sintering temperature (at 450℃, 480℃, 510℃ and 540℃, respectively). Each time the pressure is increased by 5 MPa, and the pressure is maintained for 30s before re-pressurizing. The pressure is gradually increased to 25 MPa. After heating to 500℃, keep it for 100s, then continue to heat to the sintering temperature (540℃) at a rate of 30℃ / min, and then keep it for 500s. After the holding period is over, the pressure is completely released at once. Start to cool from the sintering temperature to 350℃ at a rate of 30℃ / min, and then cool to below 100℃ at a rate of 50℃ / s. The vacuum degree is maintained better than 10 -2 Pa during the cooling process. Sintering is completed.

[0052] S4, furnace discharge and detection:

[0053] After the sintering of step S3 is completed, the vacuum is closed and the graphite mold is taken out by opening the door of the Joule heat sintering furnace; the manganese target product is pressed out of the graphite mold using a press, the graphite on the surface of the manganese target product is ground off using fine sandpaper, and the manganese target product is measured for chemical composition, density and hardness, and packaged into storage after analysis and qualification, thereby completing the preparation of the manganese target.

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

[0055] The size of the high-purity manganese target finally obtained was Φ30mmx2mm, the density of the manganese target was 7.20g / cm 3 , which was 96.3% of the theoretical density (7.474g / cm 3 ), and the hardness reached 140HV.

[0056] Example 2

[0057] Preparation of a Φ100mmx50mm high-purity manganese target:

[0058] S1, preparing raw material powder:

[0059] The electrolytic manganese powder of example 1 was used as the sintering raw material, the powder particle size was 400 mesh, and according to the product specification (Φ100mmx50mm), the electrolytic manganese powder was weighed 2863g using a balance, then the electrolytic manganese powder was placed in a stainless steel tray and then placed in a vacuum drying oven, after the room temperature vacuum degree was less than or equal to 0.5Pa, the temperature was increased and the electrolytic manganese powder was dried at 130℃ for 6h to remove the water therein, thereby completing the preparation of the raw material powder.

[0060] The mass percentage content 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 and sulfur analyzer and an ONH3000 oxygen, nitrogen and hydrogen analyzer, and the content of Fe was 0.015%, the content of S was 0.017%, the content of P was 0.0016%, the content of C was 0.006%, the content of Si was 0.001%, the content of O was 0.18%, the content of Se was 0.03%, and the content of Mn was higher than 99.74%.

[0061] S2, loading:

[0062] According to the product size Φ100mm×50mm, select the appropriate size of graphite mold (inner diameter Φ100mm, outer diameter Φ160mm, height 130mm), and according to the size of the mold cavity, make the graphite paper for sintering.

[0063] First, cover the inner wall of the graphite mold cavity and the surface of the lower head or the base plate with graphite paper, to ensure that the graphite mold does not directly contact the manganese powder; then pour the raw material powder prepared in step S1 into the graphite mold, and then place 2 layers of graphite paper on top of the raw material powder; wrap a layer of asbestos felt for heat preservation outside the graphite mold, and then insert the upper head into the mold cavity; after placing the graphite mold with the material into the joule heat sintering furnace, apply a pre-pressure of 14MPa, close the door, and start vacuumizing the joule heat sintering furnace to complete the material loading.

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

[0065] The asbestos felt is high-temperature asbestos felt (resistant to temperatures 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 asbestos felt needs to be larger than the area of the outer surface of the mold, and the length and width of the asbestos felt are higher than the outer dimensions of the graphite mold by 7mm, to ensure complete coverage of the outer surface of the graphite mold.

[0066] The upper head and the lower head are both made of graphite, with a compressive strength higher than 90MPa.

[0067] S3, sintering:

[0068] When the vacuum degree in the joule heat sintering furnace is less than 5×10 -3 Pa, start heating, and reduce the pre-pressure to 8MPa at the beginning of heating, with a heating rate of 30℃ / min. When the temperature reaches 300℃, reduce the heating rate to 15℃ / min. Apply pressure 4 times during the process from the start of heating to 420℃ to the sintering temperature (at 465℃, 510℃, 555℃, and 600℃, respectively), with each time increasing the pressure by 10MPa, maintaining the pressure for 30s before re-pressing, and gradually increasing the pressure to 48MPa. After heating to 500℃, maintain the temperature for 200s, then continue to heat to the sintering temperature (600℃) at a rate of 15℃ / min, and maintain the temperature for another 800s. After the maintenance is completed, completely release the pressure, and start to cool from the sintering temperature to 350℃ at a rate of 15℃ / min, and then cool to below 100℃ at a rate of 30℃ / s. Maintain the vacuum degree better than 10 -2 Pa during the cooling process. Complete the sintering.

[0069] S4, furnace discharge and detection:

[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 is tested by 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, and the content of Fe is 0.015%, the content of S is 0.017%, the content of P is 0.0016%, the content of C is 0.006%, the content of Si is 0.001%, the content of O is 0.18%, the content of Se is 0.03%, and the content of Mn is higher than 99.74%.

[0079] S2, charging:

[0080] According to the product size Φ 150mm*20mm, a graphite mold with a proper specification (an inner diameter Φ 150mm, an outer diameter Φ 220mm, and a height 70mm) is selected, and a graphite paper for sintering is made according to the size of the inner cavity of the mold.

[0081] Firstly, the inner wall of the inner cavity of the graphite mold and the surface of the lower pressing head or the pad are covered with the graphite paper to ensure that the graphite mold is not in direct contact with the manganese powder; then the raw material powder prepared in step S1 is poured into the graphite mold, and a layer of graphite paper is placed on the raw material powder; a layer of asbestos felt for heat preservation is sleeved outside the graphite mold, and the upper pressing head is inserted into the mold cavity; the graphite mold with the raw material is placed into the joule heat sintering furnace, a pre-pressure of 14MPa is applied, the door of the furnace is closed, the joule heat sintering furnace is started to be vacuumized, and the charging is completed.

[0082] The thickness of the graphite paper is 0.2mm, the content of carbon is higher than 99%, the tensile strength is greater than or equal to 4.0MPa, the content of sulfur is less than or equal to 300ppm, and the content of chlorine is less than or equal to 35ppm.

[0083] The asbestos felt is a high-temperature asbestos felt (resistant to temperature above 1000℃), and the thickness is 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 asbestos felt needs to be greater than the area of the outer surface of the mold, and the length and width of the asbestos felt are higher than the size of the graphite mold by 5mm to ensure that the outer surface of the graphite mold is completely covered.

[0084] The upper pressing head and the lower pressing head are both made of graphite, and the pressure resistance is higher than 90MPa.

[0085] S3, sintering:

[0086] When the vacuum degree in the joule heat sintering furnace is less than 5*10 -3After the temperature starts to rise, the pre-pressure is reduced to 8 MPa at the beginning of the temperature rise, the heating rate is 40°C / min, and when the temperature reaches 300°C, the heating rate is reduced to 20°C / min; the pressure is applied 4 times from the temperature rise to 420°C to the sintering temperature, each time the pressure is increased by 7 MPa, and after maintaining the pressure for 30 s, the pressure is increased again, and the pressure is gradually increased to 36 MPa; after heating to 500°C, the temperature is maintained for 150 s, and then the temperature is increased to the sintering temperature (580°C) at a heating rate of 20°C / min, and then maintained for 600 s, and after the maintenance is completed, the pressure is completely discharged at one time, and the temperature is decreased from the sintering temperature to 350°C at a rate of 20°C / min, and then decreased to below 100°C at a rate of 40°C / s, and the vacuum degree is maintained to be better than 10 -2 Pa during the temperature decreasing process, and the sintering is completed.

[0087] S4, discharging and detection:

[0088] After the sintering of step S3 is completed, the vacuum is closed and the gas is discharged, the door of the Joule heat sintering furnace is opened, and the graphite mold is taken out; the manganese target product is pressed out of the graphite mold using a press, the graphite on the surface of the manganese target product is ground off using fine sandpaper, and the corresponding chemical composition, density and hardness of the manganese target product are measured, and after the analysis is qualified, the manganese target product is packaged and stored, and the preparation of the manganese target material is completed.

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

[0090] The size of the finally obtained high-purity manganese target material is Φ150mmx20mm, and the density of the manganese target material is 7.32g / cm 3 , reaching 98.0% of the theoretical density (7.474g / cm 3 ), and the hardness reaches 209HV.

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

[0092] Example 4

[0093] Preparation of Φ78mmx3.5mm high-purity manganese target material:

[0094] S1, preparing raw material powder:

[0095] The electrolytic manganese powder of Example 1 was used as the sintering raw material, the powder particle size was 300 mesh and 400 mesh, each accounting for 50%, according to the product specification (Φ78mmx3.5mm), the electrolytic manganese powder was weighed by a balance, 121g, then the electrolytic manganese powder was put into a stainless steel tray, and then put into a vacuum drying oven, after the room temperature vacuum degree was less than or equal to 0.5Pa, the temperature was started to be raised and dried at 120℃ for 4h, and the moisture in the electrolytic manganese powder was removed, and the preparation of the raw material powder was completed.

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

[0097] S2, loading:

[0098] According to the product size Φ78mmx3.5mm, a graphite mold of appropriate size was selected (inner diameter Φ78mm, outer diameter Φ150mm, height 40mm), and a graphite paper for sintering was made according to the size of the mold cavity.

[0099] First, the inner wall of the graphite mold cavity and the surface of the lower pressing head or the base plate were covered with graphite paper to ensure that the graphite mold and the manganese powder had no direct contact; then the raw material powder prepared in step S1 was poured into the graphite mold, and then a layer of graphite paper was placed on the raw material powder, a layer of asbestos felt for heat preservation was wrapped outside the graphite mold, and the upper pressing head was inserted into the mold cavity; the graphite mold loaded with the raw material was placed in the joule heat sintering furnace, a pre-pressure of 12MPa was applied, the door of the furnace was closed, the joule heat sintering furnace was started to be vacuumized, and the loading was completed.

[0100] The thickness of the graphite paper was 0.1mm, the carbon content was higher than 99%, the tensile strength was greater than or equal to 4.1MPa, the sulfur content was less than or equal to 300ppm, and the chlorine content was less than or equal to 35ppm.

[0101] The asbestos felt was high-temperature asbestos felt (resistant to temperature above 1000℃), the thickness was 7mm, the size of the asbestos felt was determined according to the size of the outer surface of the sintering mold, the surface area of the asbestos felt needed to be greater than the area of the outer surface of the mold, and the length and width of the asbestos felt were higher than the size of the graphite mold by 5mm to ensure that the outer surface of the graphite mold was completely covered.

[0102] The upper pressing head and the lower pressing head were both made of graphite, and the pressure resistance was higher than 90MPa.

[0103] S3, sintering:

[0104] When the vacuum degree in the Joule heat sintering furnace is less than 6x10 -3 Pa, the temperature starts to rise, the pre-pressure is reduced to 8 MPa at the beginning of the temperature rise, the heating rate is 50℃ / min, when the temperature reaches 300℃, the heating rate is reduced to 20℃ / min; the pressure is applied 4 times from the beginning of the temperature rise to 420℃ to the sintering temperature, each time the pressure is increased by 6 MPa, the pressure is maintained for 30s before the next pressure increase, and the pressure is gradually increased to 32 MPa; after heating to 500℃, the temperature is maintained for 180s, then the temperature is continuously increased to the sintering temperature (560℃) at a heating rate of 20℃ / min, and then maintained for 700s, after the maintenance is completed, the pressure is completely discharged at once, and then the temperature is decreased from the sintering temperature to 350℃ at a rate of 18℃ / min, and then decreased to below 100℃ at a rate of 35℃ / s, the vacuum degree is maintained to be better than 10 -2 Pa during the temperature decreasing process, and the sintering is completed.

[0105] S4, discharging and detection:

[0106] After the sintering of step S3 is completed, the vacuum is closed and the gas is discharged, the door of the Joule heat sintering furnace is opened to take out the graphite mold; the manganese target product is pressed out of the graphite mold using a press, the graphite on the surface of the manganese target product is ground off using fine sandpaper, and the corresponding chemical composition, density and hardness of the manganese target product are measured, the analysis is qualified, and the manganese target product is packaged and stored, and the preparation of the manganese target material is completed.

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

[0108] The size of the finally obtained high-purity manganese target material is Φ78mmx3.5mm, the density of the manganese target material is 7.23g / cm 3 , which reaches 96.8% of the theoretical density (7.474g / cm 3 ), and the hardness reaches 195HV.

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

[0110] The above detailed description of the embodiments of the present application is only preferred embodiments of the present application, and should not be considered as limiting the scope of the present application. Any equivalent changes and improvements made within the scope of the present application should still be considered as falling within the scope of the present application.

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.

Images