CN114031403A - Preparation method of gadolinium oxysulfide scintillating ceramic and application of gadolinium oxysulfide scintillating ceramic - Google Patents
Preparation method of gadolinium oxysulfide scintillating ceramic and application of gadolinium oxysulfide scintillating ceramic Download PDFInfo
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- MCVAAHQLXUXWLC-UHFFFAOYSA-N [O-2].[O-2].[S-2].[Gd+3].[Gd+3] Chemical compound [O-2].[O-2].[S-2].[Gd+3].[Gd+3] MCVAAHQLXUXWLC-UHFFFAOYSA-N 0.000 title claims abstract description 134
- 239000000919 ceramic Substances 0.000 title claims abstract description 114
- 238000002360 preparation method Methods 0.000 title claims abstract description 30
- 238000005245 sintering Methods 0.000 claims abstract description 151
- 239000000843 powder Substances 0.000 claims abstract description 64
- 238000000034 method Methods 0.000 claims abstract description 51
- 238000002490 spark plasma sintering Methods 0.000 claims abstract description 29
- 238000007731 hot pressing Methods 0.000 claims abstract description 13
- 238000000498 ball milling Methods 0.000 claims description 75
- 238000001816 cooling Methods 0.000 claims description 40
- 238000000137 annealing Methods 0.000 claims description 28
- 239000012298 atmosphere Substances 0.000 claims description 20
- 239000002994 raw material Substances 0.000 claims description 20
- 239000000463 material Substances 0.000 claims description 17
- 238000002156 mixing Methods 0.000 claims description 13
- 239000002245 particle Substances 0.000 claims description 11
- 238000010438 heat treatment Methods 0.000 claims description 10
- 238000009659 non-destructive testing Methods 0.000 claims description 4
- 230000000630 rising effect Effects 0.000 claims description 4
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical group CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 2
- 238000013170 computed tomography imaging Methods 0.000 claims description 2
- 230000001681 protective effect Effects 0.000 claims 1
- 230000008569 process Effects 0.000 abstract description 16
- 229910052777 Praseodymium Inorganic materials 0.000 abstract description 12
- 238000001513 hot isostatic pressing Methods 0.000 abstract description 11
- 238000007789 sealing Methods 0.000 abstract description 9
- 238000004519 manufacturing process Methods 0.000 abstract description 8
- 230000009286 beneficial effect Effects 0.000 abstract description 6
- 229910052771 Terbium Inorganic materials 0.000 abstract description 5
- 230000007547 defect Effects 0.000 abstract description 5
- 238000005516 engineering process Methods 0.000 abstract description 5
- 229910052751 metal Inorganic materials 0.000 abstract description 5
- 239000002184 metal Substances 0.000 abstract description 5
- 229910052693 Europium Inorganic materials 0.000 abstract description 3
- 229910052772 Samarium Inorganic materials 0.000 abstract description 3
- 229910052769 Ytterbium Inorganic materials 0.000 abstract description 3
- 229910052775 Thulium Inorganic materials 0.000 abstract description 2
- 238000000465 moulding Methods 0.000 abstract description 2
- MCMNRKCIXSYSNV-UHFFFAOYSA-N Zirconium dioxide Chemical compound O=[Zr]=O MCMNRKCIXSYSNV-UHFFFAOYSA-N 0.000 description 62
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 32
- 239000011324 bead Substances 0.000 description 30
- 229910002804 graphite Inorganic materials 0.000 description 30
- 239000010439 graphite Substances 0.000 description 30
- 239000013078 crystal Substances 0.000 description 16
- 238000000227 grinding Methods 0.000 description 16
- 238000005498 polishing Methods 0.000 description 16
- 238000004321 preservation Methods 0.000 description 10
- 229910052582 BN Inorganic materials 0.000 description 8
- PZNSFCLAULLKQX-UHFFFAOYSA-N Boron nitride Chemical compound N#B PZNSFCLAULLKQX-UHFFFAOYSA-N 0.000 description 8
- 238000005520 cutting process Methods 0.000 description 8
- 239000012535 impurity Substances 0.000 description 8
- 238000011049 filling Methods 0.000 description 7
- 150000002500 ions Chemical class 0.000 description 6
- 238000001514 detection method Methods 0.000 description 5
- 238000003384 imaging method Methods 0.000 description 4
- 238000012545 processing Methods 0.000 description 3
- 230000005855 radiation Effects 0.000 description 3
- 229910052761 rare earth metal Inorganic materials 0.000 description 3
- 229910052799 carbon Inorganic materials 0.000 description 2
- 238000009792 diffusion process Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000007689 inspection Methods 0.000 description 2
- 238000003754 machining Methods 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 239000011148 porous material Substances 0.000 description 2
- -1 rare earth oxysulfides Chemical class 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 229910052684 Cerium Inorganic materials 0.000 description 1
- 229910052692 Dysprosium Inorganic materials 0.000 description 1
- 229910052689 Holmium Inorganic materials 0.000 description 1
- 230000004913 activation Effects 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 239000012300 argon atmosphere Substances 0.000 description 1
- 238000000149 argon plasma sintering Methods 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 230000006835 compression Effects 0.000 description 1
- 238000007906 compression Methods 0.000 description 1
- 238000002591 computed tomography Methods 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 238000000280 densification Methods 0.000 description 1
- TXKMVPPZCYKFAC-UHFFFAOYSA-N disulfur monoxide Inorganic materials O=S=S TXKMVPPZCYKFAC-UHFFFAOYSA-N 0.000 description 1
- 239000002019 doping agent Substances 0.000 description 1
- 239000010419 fine particle Substances 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 229910052747 lanthanoid Inorganic materials 0.000 description 1
- 150000002602 lanthanoids Chemical class 0.000 description 1
- 230000031700 light absorption Effects 0.000 description 1
- 238000011068 loading method Methods 0.000 description 1
- 229910003443 lutetium oxide Inorganic materials 0.000 description 1
- 239000011812 mixed powder Substances 0.000 description 1
- 238000009206 nuclear medicine Methods 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 239000007858 starting material Substances 0.000 description 1
- XTQHKBHJIVJGKJ-UHFFFAOYSA-N sulfur monoxide Chemical compound S=O XTQHKBHJIVJGKJ-UHFFFAOYSA-N 0.000 description 1
- GZCRRIHWUXGPOV-UHFFFAOYSA-N terbium atom Chemical compound [Tb] GZCRRIHWUXGPOV-UHFFFAOYSA-N 0.000 description 1
- 229920001169 thermoplastic Polymers 0.000 description 1
- 239000004416 thermosoftening plastic Substances 0.000 description 1
- 238000002834 transmittance Methods 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
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Abstract
The invention discloses a preparation method of gadolinium oxysulfide scintillating ceramic, which is characterized in that Gd is sintered by one step by a vacuum hot-pressing sintering or discharge plasma sintering method2O2And sintering and molding the S scintillation powder to efficiently obtain the gadolinium oxysulfide polycrystalline scintillation ceramic doped with at least one element of Pr, Eu, Tb, Sm, Yb and Tm. The method can obtain the gadolinium oxysulfide scintillating ceramic with qualified quality by one-time sintering, does not need to perform secondary sintering by using SPS (spark plasma sintering) or uniaxial hot pressing combined hot isostatic pressing, and solves the defects that a blank needs to be sintered firstly, gadolinium oxysulfide powder metal needs a vacuum sealing process, the cost is high and the process is complex in the current hot isostatic pressing technology; make the production workerThe process is more energy-saving and more efficient. The invention combines the sintering temperature rise rate with the pressure, the temperature and the time, effectively ensures the characteristics of fine grain size and high density of the gadolinium oxysulfide scintillating ceramic finished product, and is beneficial to popularization and use.
Description
Technical Field
The invention belongs to the technical field of preparation of scintillating ceramics, and particularly relates to a preparation method of gadolinium oxysulfide scintillating ceramics and application of the gadolinium oxysulfide scintillating ceramics.
Background
Gadolinium oxysulfide has a hexagonal structure, has high stopping power on X-rays, has a band gap of 4.6 eV, and has high luminous efficiency, strong oxidation resistance, high light absorption rate and high transmission efficiency. Due to the presence of anisotropy, birefringence exists at grain boundaries, and transparent ceramics are not easily prepared. Doping of rare earth oxysulfides with ions (RE)2O2S: ln lanthanoid), where RE is a rare earth element and Ln is a dopant ion, which is at least one element of Pr, Eu, Tb, Sm, Yb, Tm, Ho, Dy. The single crystal material scintillation material has the defects of complex preparation process, long production period, high cost, poor machining performance and stability and the like, and if the scintillation single crystal is doped, doped ions are unevenly distributed in the crystal growth process, so that the imaging quality of X-CT is reduced. Such as single crystal scintillating material NaI: the T1 afterglow is long, and the radiation damage is serious; CsI: t1 has long afterglow and serious retardation; bi4Ge3O12(BGO) has low luminous efficiency and low light output; CdWO4Toxic, radiation damage up to 3%. Compared with scintillation single crystal, the scintillation ceramic has the characteristics of stable physical and chemical properties, simple preparation process, low cost, easy realization of uniform doping, good machining performance and the like, and is an ideal material for replacing the scintillation single crystal. Compared with the scintillation powder, the scintillation ceramic can improve the density, reduce the light scattering, ensure that the scintillation light is completely transmitted, is convenient to process into micron-sized small strips with certain gaps, and can improve the resolution of images. Compared with ceramics YGO, GGG and Lu2O3：Eu3+GOS has high light output, especially Gd2O2S: pr, Ce, F scintillating ceramic is anisotropic optically, has double refraction at crystal boundary, is doped with Pr3+、Ce3+The maximum emission wavelength of the F ions is 520 nm, afterglow is inhibited, radiation damage is reduced, and luminous efficiency is increased, so that the F ions are widely applied to the extremely fast imaging fields of medical CT instruments, nuclear medicine imaging, industrial nondestructive testing, high-energy physical particle detection, airport security inspection, X-ray microscopes, water window soft X-ray screens and the like.
The components of ray detection devices such as security inspection machines and nondestructive testing mainly comprise two parts, namely a photodiode and a scintillator, wherein the scintillator emits visible light after absorbing high-energy rays, and the performance of the scintillator influences the overall performance index and the detection effect of the ray detection device to a great extent.
Rare earth ion doped Gd2O2S scintillating ceramics are sulfur oxide scintillators that have developed after the 80' S of the 20 th century. US5296163 to Siemens, 1994, discloses gadolinium oxysulfide scintillating ceramics with BET of 35m without the use of compression additives or sintering aids2The powder hot pressed sintering in g gives a high density ceramic with a regular columnar to spherical grain structure, an average grain size of about 50um, and a theoretical density of 99.9% or higher. Philips in 2013, WO2013014557A1, discloses a terbium scintillator detector based on Gd2O2S: a scintillator array (118) of Pr, Tb, Ce for use in an imaging system as a computed tomography scanner.
Gd is the most widely used in medical CT in the world at present2O2And (4) S ceramic. Hot isostatic pressing sintering of Gd2O2S ceramic, a green body needs to be sintered to obtain certain density, closed air holes are formed in the green body, then the green body needs to be sealed and packaged, and is sintered at high pressure and high temperature under argon atmosphere, so that a large amount of gas is consumed, the process is complex, the cost is high, and Gd is greatly limited2O2Application of S ceramic.
The technology is searched and published under the number CN105330289A, and a preparation method of gadolinium oxysulfide scintillating ceramic is disclosed, wherein a sintering aid is added into scintillating ceramic powder and is uniformly mixed; putting the scintillating ceramic powder added with the sintering aid into a sintering mold, and performing discharge plasma sintering to obtain a gadolinium oxysulfide sintered body; and annealing the gadolinium oxysulfide sintered body, and optionally performing hot isostatic pressing secondary sintering and secondary annealing to obtain the gadolinium oxysulfide scintillating ceramic. In the method, the density of the GOS ceramic is improved, and two times of sintering are required. And the process conditions of the two-time sintering need to be strictly controlled to achieve a product with high density. For example: in order to avoid excessive growth of primary sintering grains which is not beneficial to densification and growth of ceramics during secondary sintering, the temperature during primary sintering needs to be controlled not to be too high. The lower spark plasma sintering temperature is simultaneously beneficial to reducing carbon diffusion pollution. That is, under the corresponding powder activity and pressure conditions, the temperature of the primary hot press sintering is required to be as low as possible and the minimum temperature required to sinter the powder to form closed pores. For GOS powder with the grain diameter of 1-9 μm, the discharge plasma sintering temperature is 1200-1500 ℃ under the pressure of 50-200 MPa. If the temperature is lower than 1200 ℃, the sintering is insufficient, closed pores are not formed in the sintered body completely, and the density cannot be improved by hot isostatic pressing secondary sintering; if the temperature is higher than 1500 ℃, the sintering is excessive, although the density can reach 99.9%, carbon diffusion pollution is serious, the light transmittance is poor, crystal grains grow excessively and are thick, the ceramic body is very brittle, and the subsequent scintillator array processing is difficult.
In conclusion, Gd2O2The preparation of S ceramic is complex, the S ceramic can be formed only by sintering for many times, and the technical difficulty is high, so that the invention of gadolinium oxysulfide scintillating ceramic which can be successfully obtained at low temperature in short time at one time is very necessary.
Disclosure of Invention
Aiming at the defects of the prior art, the invention provides a preparation method of gadolinium oxysulfide scintillating ceramic, which is characterized in that Gd is sintered by a one-step sintering method of vacuum hot-pressing sintering or discharge plasma sintering2O2Sintering and molding the S scintillation powder to efficiently obtain gadolinium oxysulfide (chemical formula Gd) doped with at least one element of Pr, Eu, Tb, Sm, Yb and Tm2O2S) polycrystalline scintillating ceramic.
The method can obtain the gadolinium oxysulfide scintillating ceramic with qualified quality by one-time sintering, does not need to perform secondary sintering by adopting a discharge plasma process (SPS) or a method of combining uniaxial hot pressing with hot isostatic pressing, and solves the defects that a green body needs to be sintered firstly in the current hot isostatic pressing technology, gadolinium oxysulfide powder metal needs a vacuum sealing process, the cost is high and the process is complex; the product meeting the use performance can be obtained by one-step sintering, so that the production process is more energy-saving and efficient, and the yield is high.
The invention also discloses application of the gadolinium oxysulfide scintillating ceramic prepared by the preparation method of the gadolinium oxysulfide scintillating ceramic, which is applied to the fields of X-ray detectors, fluorescent screens, security check machines, nondestructive testing, gadolinium oxysulfide fluorescent screens in DR detectors and computed tomography imaging.
The purpose of the invention is realized by the following technical scheme:
discloses a preparation method of gadolinium oxysulfide scintillating ceramic, which comprises the following steps:
s1, mixing the raw materials: adding a sintering aid into the gadolinium oxysulfide powder and uniformly mixing;
s2, ball milling treatment: ball milling to obtain uniform powder;
s3, one-step sintering treatment: performing vacuum sintering or spark plasma sintering on the powder subjected to ball milling treatment in the step S2;
wherein, the vacuum sintering comprises the following steps: the powder is loaded in a vacuum hot pressing furnace, the temperature rising rate of initial sintering is 5-50 ℃/min, the pressure is 25-100MPa, the temperature is 800-; continuously heating, sintering at the heating rate of 5-20 ℃/min, 45-200 MPa and 1800 ℃ at 1000 ℃ and keeping the temperature for 1-3 h;
the discharge plasma sintering is as follows: putting the powder into a sintering mold of an SPS method, putting the powder into a furnace for pre-pressurizing at 15-25MPa, raising the temperature to 500-100 ℃/min, keeping the temperature for 10-20min, continuing raising the temperature to 1800 ℃ and keeping the temperature at 25-45MPa, and keeping the temperature for 0.5-1 h;
s4, cooling treatment after sintering: cooling the sintered powder to room temperature;
s5, annealing treatment: annealing treatment is carried out at the temperature of 800-: and obtaining the gadolinium oxysulfide scintillating ceramic blank after 0.5-3 h.
Further, in step S1, the sintering aid is LiF or Li2GeF6(ii) a According to the mass ratio, the addition amount of the sintering aid is 0.05-1.5% of the addition amount of the gadolinium oxysulfide powder.
Furthermore, the gadolinium oxysulfide powder has a median particle size of 3-20 μm.
Further, in step S2, the ball-milling ratio of balls to materials is 2-10: 1; the ball milling is carried out under the protection condition; the ball milling time is 8-36 h.
Further, zirconia beads are used for ball milling treatment, the zirconia beads are selected from different diameters of large, medium and small specifications for proportioning, the average diameter of the zirconia beads is selected to be 4-8mm, and the mass ratio of the zirconia beads is 1: 2-5: 5-10.
The diameter of the zirconia is adjusted according to three specifications of large, medium and small, so that the ball-milled gadolinium oxysulfide powder can be ball-milled uniformly and has fine particles.
Further, the protection condition of the ball milling treatment is absolute ethyl alcohol or Ar atmosphere.
Further, the annealing treatment is performed in an Ar atmosphere.
Further, the purity of the gadolinium oxysulfide powder is 99.995% or more.
Further, after the vacuum sintering in the step S3, when the temperature in the furnace is higher than 1300 ℃, the temperature is reduced to 800-1300 ℃ at the temperature reduction rate of 10-50 ℃/min, and then the temperature is reduced to room temperature at the temperature reduction rate of 10-20 ℃/min, so as to obtain the gadolinium oxysulfide scintillating ceramic sintered body. When the temperature is too high, the crystal grains grow too fast, the crystal grains are coarse, the grain boundary is coarse, the obtained ceramic has high brittleness, and the later processing is easy to crack. The temperature can be effectively controlled by the arrangement to ensure grain refinement.
As a parallel scheme, after the discharge plasma sintering of the step S3, the temperature is reduced at a rate of 10-20 ℃/min until the temperature is reduced to room temperature, and a high-density gadolinium oxysulfide scintillating ceramic sintered body is obtained. The cooling step of the method does not need the complexity of vacuum sintering, because the heat preservation time of spark plasma sintering is shorter, the sintering can be completed according to the sintering process in a shorter time, crystal grains can not grow too fast in a shorter time, and the crystal grains still keep fine.
Compared with the prior art, the invention has the following beneficial effects:
the preparation method of the gadolinium oxysulfide scintillating ceramic provided by the invention has the advantages that the raw materials are scientifically proportioned, the raw materials are sintered in one step according to the characteristics of the raw materials, and the crystal grains of the gadolinium oxysulfide scintillating ceramic are refined by adjusting the technological parameters of pressurization, temperature rise and heat preservation and combining the cooling process, so that the gadolinium oxysulfide scintillating ceramic has good compactness and extremely low porosity.
The invention combines the sintering temperature rise rate with the pressure, the temperature and the time, effectively ensures the characteristics of fine grain size and high density of the gadolinium oxysulfide scintillating ceramic finished product, and is beneficial to popularization and use.
Two sintering methods are used in the invention, and both can be sintered in one step to sinter and shape the gadolinium oxysulfide scintillating ceramic:
the first method is to use a vacuum hot-pressing sintering method to sinter the high-density gadolinium oxysulfide scintillating ceramic, which is easy to obtain a sintered body with the theoretical density and the porosity close to zero, can realize the preparation of the high-efficiency high-density gadolinium oxysulfide scintillating ceramic by one step, and is easy to obtain the fine-grained gadolinium oxysulfide scintillating ceramic. The technical bottleneck of secondary sintering by using an SPS (spark plasma sintering) or uniaxial hot pressing combined hot isostatic pressing method is broken through, and the problems that a blank needs to be sintered firstly, gadolinium oxysulfide powder metal needs a vacuum sealing process, the cost is high and the process is complex in the current hot isostatic pressing technology are solved.
The first method adopts spark plasma sintering, and the method does not need to perform secondary sintering by combining SPS (spark plasma sintering) or uniaxial hot pressing primary sintering with hot isostatic pressing, does not need to sinter a blank firstly, and overcomes the defects that the existing vacuum hot pressing sintering technology has high sintering pressure, expensive mould and long time consumption, and GOS powder metal in the traditional hot isostatic pressing method needs a sheath vacuum sealing process. The method has low technical difficulty, and the GOS sintered body can be successfully obtained at one time.
Meanwhile, the preparation method of the gadolinium oxysulfide scintillating ceramic effectively shortens the working procedure time, reduces the production cost and is beneficial to popularization and application.
Drawings
FIG. 1 is a flow chart of a production process of a vacuum hot-pressing sintering method of the preparation method of gadolinium oxysulfide scintillating ceramic.
FIG. 2 is a flow chart of a discharge plasma sintering production process of the gadolinium oxysulfide scintillating ceramic preparation method of the present invention.
Detailed Description
The following specific examples further illustrate the invention in detail. Unless otherwise indicated, the various starting materials used in the examples of the present invention are either conventionally available commercially or prepared according to conventional methods in the art using equipment commonly used in the laboratory. Unless defined or stated otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.
The invention discloses a preparation method of gadolinium oxysulfide scintillating ceramic, which comprises the following steps:
s1, mixing the raw materials: adding a sintering aid LiF or Li into gadolinium oxysulfide powder2GeF6The addition amount of the sintering aid is 0.05-1.5% of the addition amount of the gadolinium oxysulfide powder according to the mass ratio;
s2, ball milling treatment: selecting a ball material ratio of 2-10: 1, ball milling is carried out under the protection condition; the ball milling time is 8-36h, and uniformly mixed powder is obtained;
s3, one-step sintering treatment: performing vacuum sintering or spark plasma sintering on the powder subjected to ball milling treatment in the step S2;
wherein, the vacuum sintering comprises the following steps: the powder is loaded in a vacuum hot pressing furnace, the temperature rising rate of initial sintering is 5-50 ℃/min, the pressure is 25-100MPa, the temperature is 800-; continuously heating, sintering at the heating rate of 5-20 ℃/min, 45-200 MPa and 1800 ℃ at 1000 ℃ and keeping the temperature for 1-3 h;
the discharge plasma sintering is as follows: the powder is put into a sintering mold of an SPS method, and is put into a furnace for pre-pressurizing at 15-25MPa, the heating rate is 10-100 ℃/min, the temperature is raised to 500-plus-material temperature of 1000 ℃, the temperature is kept for 10-20min, the temperature is continuously raised to 1200-plus-material temperature of 1800 ℃, the pressure is raised to 25-45MPa, and the temperature is kept for 0.5-1 h.
S4, cooling treatment after sintering: after the vacuum sintering in the step S3, when the temperature in the furnace is higher than 1300 ℃, reducing the temperature to 800-1300 ℃ at the cooling rate of 10-50 ℃/min until the temperature is cooled to the room temperature, and obtaining a gadolinium oxysulfide scintillating ceramic sintered body;
or after the discharge plasma sintering in the step S3, cooling at a cooling rate of 10-20 ℃/min until the temperature is cooled to room temperature, and obtaining a high-density gadolinium oxysulfide scintillating ceramic sintered body;
s5, annealing treatment: annealing treatment is carried out at the temperature of 800-1200 ℃, the annealing heat preservation time is 0.5-3h, and the gadolinium oxysulfide scintillating ceramic with the density of 95.5-99.95% and a semitransparent blank body are obtained.
Example 1
The preparation method of the gadolinium oxysulfide scintillating ceramic of the embodiment comprises the following steps:
s1, mixing the raw materials: 2kg of commercial Gd having a purity of 99.999% and a median particle size of 3 μm were weighed2O2Pr, Ce scintillating ceramic powder, 2g of Li is added2GeF6And (3) a sintering aid.
S2, ball milling treatment: the ball-material ratio is 2:1, zirconia beads are used for ball milling treatment, the zirconia beads are selected from different diameters of large, medium and small specifications for proportioning, the average diameter of the zirconia beads is 4mm, 6mm and 8mm, and the mass ratio of the zirconia beads is 1:3:5 according to the order of the diameters.
Putting the mixture into a ball milling tank, introducing Ar atmosphere, sealing the ball milling tank, and finally putting the ball milling tank into a planetary ball mill for ball milling for 8 hours at the rotating speed of 800 rmp.
S3, vacuum sintering: and filling the gadolinium oxysulfide powder subjected to ball milling into a graphite mold, attaching a layer of graphite paper to the inner wall of the graphite mold, and then putting the sintering mold filled with the gadolinium oxysulfide powder into a vacuum sintering furnace for sintering. The temperature rise rate of the initial sintering is 25 ℃/min, the pressure is 30MPa, the temperature is between 800 ℃ and 850 ℃, and the heat preservation is carried out for 2 h; then, the temperature is continuously raised, the heating rate is 10 ℃/min, the pressure is 45MPa, the temperature is 1200 ℃ for sintering, and the temperature is kept for 90 min.
S4, cooling treatment after sintering: after the vacuum sintering and heat preservation are finished, reducing the temperature to 1000-1300 ℃ at the cooling rate of 10 ℃/min, and then cooling to room temperature at the cooling rate of 10 ℃/min to obtain a gadolinium oxysulfide scintillating ceramic sintered body; when the temperature is too high, the crystal grains grow too fast, the crystal grains are coarse, the grain boundary is coarse, the obtained ceramic has high brittleness, and the later processing is easy to crack. The method can effectively control the temperature to ensure the grain refinement.
S5, annealing treatment: the sintered body obtained in the above step is subjected to a simple treatment. Firstly removing impurities of boron nitride and graphite paper attached to the surface, then polishing a gadolinium oxysulfide sintered body, and finally annealing the polished gadolinium oxysulfide sintered body for 2 hours at 800 ℃ in a muffle furnace in an Ar atmosphere. The annealing treatment can further refine the grains.
And carrying out coarse grinding, fine grinding, cutting and polishing on the annealed sample to obtain the gadolinium oxysulfide scintillating ceramic.
Example 2
The preparation method of the gadolinium oxysulfide scintillating ceramic of the embodiment comprises the following steps:
s1, mixing the raw materials: 2kg of commercial Gd having a purity of 99.999% and a median particle size of 3 μm were weighed2O2Pr, Ce scintillating ceramic powder, 30g of Li is added2GeF6And (3) a sintering aid.
S2, ball milling treatment: the ball material ratio is 10: 1; zirconia beads are used for ball milling treatment, the zirconia beads are selected from different diameters of large, medium and small specifications for proportioning, the average diameter of the zirconia beads is selected from three types of 4mm, 6mm and 8mm, and the mass ratio of the zirconia beads is 1:2:5 according to the large, medium and small sequence of the diameters. Putting the raw materials into a ball milling tank, introducing Ar atmosphere, sealing the ball milling tank, and finally putting the ball milling tank into a planetary ball mill for ball milling for 30 hours at the rotating speed of 500 rmp.
S3, vacuum sintering: and filling the gadolinium oxysulfide powder subjected to ball milling into a graphite mold, attaching a layer of graphite paper to the inner wall of the graphite mold, and then putting the sintering mold filled with the gadolinium oxysulfide powder into a vacuum sintering furnace for sintering. The temperature rising rate of the initial sintering is 10 ℃/min, the pressure is 100MPa, the temperature is 900-950 ℃, and the temperature is kept for 40 min; then, the temperature is continuously raised, the heating rate is 50 ℃/min, the pressure is 200MPa, the temperature is 1800 ℃, sintering is carried out, and the temperature is kept for 180 min.
S4, cooling treatment after sintering: after the vacuum sintering is finished, the temperature is reduced to 800-1100 ℃ at the cooling rate of 20 ℃/min, and then the temperature is reduced to room temperature at the cooling rate of 20 ℃/min, so as to obtain the gadolinium oxysulfide scintillating ceramic sintered body.
S5, annealing treatment: the sintered body obtained in the above step is subjected to a simple treatment. Firstly removing impurities of boron nitride and graphite paper attached to the surface, then polishing a gadolinium oxysulfide sintered body, and finally annealing the polished gadolinium oxysulfide sintered body for 2 hours at 1000 ℃ in an Ar atmosphere in a muffle furnace.
And carrying out coarse grinding, fine grinding, cutting and polishing on the annealed sample to obtain the gadolinium oxysulfide scintillating ceramic.
Example 3
The preparation method of the gadolinium oxysulfide scintillating ceramic of the embodiment comprises the following steps:
s1, mixing the raw materials: 2kg of commercial Gd having a purity of 99.999% and a median particle size of 20 μm were weighed2O2Pr, Ce scintillating ceramic powder, and 10g LiF sintering aid is added.
S2, ball milling treatment: the ball-material ratio is 3:1, zirconia beads are used for ball milling treatment, the zirconia beads are selected from different diameters of large, medium and small specifications to be matched, the average diameter of the zirconia beads is 4mm, 6mm and 8mm, and the mass ratio of the zirconia beads is 2:5:10 according to the order of the diameters. Putting the raw materials into a ball milling tank, introducing Ar atmosphere, sealing the ball milling tank, and finally placing the ball milling tank into a planetary ball mill for ball milling for 12 hours at the rotating speed of 800 rmp.
S3, vacuum sintering: and filling the gadolinium oxysulfide powder subjected to ball milling into a graphite mold, attaching a layer of graphite paper to the inner wall of the graphite mold, and then putting the sintering mold filled with the gadolinium oxysulfide powder into a vacuum sintering furnace for sintering. The temperature rise rate of the initial sintering is 50 ℃/min, the pressure is 45MPa, the temperature is between 850 ℃ and 880 ℃, and the heat preservation is carried out for 6 h; then, the temperature is continuously increased, the temperature increasing rate is 5 ℃/min, the pressure is 200MPa, the temperature is 1100-.
S4, cooling treatment after sintering: after the vacuum sintering is finished, the temperature is reduced to 1200 ℃ at the cooling rate of 30 ℃/min, and then the temperature is reduced to room temperature at the cooling rate of 20 ℃/min, so as to obtain the gadolinium oxysulfide scintillating ceramic sintered body.
S5, annealing treatment: the sintered body obtained in the above step is subjected to a simple treatment. Firstly removing impurities of boron nitride and graphite paper attached to the surface, then polishing a gadolinium oxysulfide sintered body, and finally annealing the polished gadolinium oxysulfide sintered body for 3 hours at 800 ℃ in a muffle furnace in Ar atmosphere.
And carrying out coarse grinding, fine grinding, cutting and polishing on the annealed sample to obtain the gadolinium oxysulfide scintillating ceramic.
Example 4
The preparation method of the gadolinium oxysulfide scintillating ceramic of the embodiment comprises the following steps:
s1, mixing the raw materials: 2kg of commercial Gd having a purity of 99.999% and a median particle size of 8 μm were weighed2O2Pr, Ce scintillating ceramic powder, 2g of Li is added2GeF6And (3) a sintering aid.
S2, ball milling treatment: the ball-material ratio is 2:1, zirconia beads are used for ball milling treatment, the zirconia beads are selected from different diameters of large, medium and small specifications for proportioning, the average diameter of the zirconia beads is 4mm, 6mm and 8mm, and the mass ratio of the zirconia beads is 1:3:6 according to the order of the diameters. Putting the raw materials into a ball milling tank, introducing Ar atmosphere, sealing the ball milling tank, and finally placing the ball milling tank into a planetary ball mill for ball milling for 15 hours at the rotating speed of 800 rmp.
S3, vacuum sintering: and filling the gadolinium oxysulfide powder subjected to ball milling into a graphite mold, attaching a layer of graphite paper to the inner wall of the graphite mold, and then putting the sintering mold filled with the gadolinium oxysulfide powder into a vacuum sintering furnace for sintering. The temperature rise rate of the initial sintering is 30 ℃/min, the pressure is 150MPa, the temperature is 830-850 ℃, and the temperature is kept for 10 h; then, the temperature is continuously increased, the temperature increasing rate is 10 ℃/min, the pressure is 120MPa, the temperature is 1200 ℃ and 1300 ℃, and the temperature is kept for 90 min.
S4, cooling treatment after sintering: after the vacuum sintering is finished, the temperature is reduced to 820 ℃ at the cooling rate of 10 ℃/min, and then the temperature is reduced to room temperature at the cooling rate of 20 ℃/min, so as to obtain the gadolinium oxysulfide scintillation ceramic sintered body.
S5, annealing treatment: the sintered body obtained in the above step is subjected to a simple treatment. Firstly removing impurities of boron nitride and graphite paper attached to the surface, then polishing a gadolinium oxysulfide sintered body, and finally annealing the polished gadolinium oxysulfide sintered body for 0.5h at 900 ℃ in a muffle furnace in Ar atmosphere.
And carrying out coarse grinding, fine grinding, cutting and polishing on the annealed sample to obtain the gadolinium oxysulfide scintillating ceramic.
In the methods of the embodiments 1 to 4, the production process shown in fig. 1 is used, and the sintered high-density gadolinium oxysulfide scintillating ceramic is sintered by a vacuum hot-pressing sintering method, so that a sintered body with a theoretical density and a porosity close to zero is easily obtained, the preparation of the high-efficiency high-density gadolinium oxysulfide scintillating ceramic can be realized in one step, and the fine-grained gadolinium oxysulfide scintillating ceramic is easily obtained. The density of the gadolinium oxysulfide scintillating ceramic prepared by the methods of the embodiments 1 to 4 is detected to be within the range of 98.3 to 99.9 percent.
Example 5
The preparation method of the gadolinium oxysulfide scintillating ceramic of the embodiment comprises the following steps:
s1, mixing the raw materials: 200g of commercial Gd having a purity of 99.995% and a median particle size of 3 μm were weighed out2O2Pr, Ce scintillating ceramic powder, 0.2g of Li is added2GeF6And (3) a sintering aid.
S2, ball milling treatment: the ball-material ratio is 8:1, zirconia beads are used for ball milling treatment, the zirconia beads are selected from different diameters of large, medium and small specifications for proportioning, the average diameter of the zirconia beads is 4mm, 6mm and 8mm, and the mass ratio of the zirconia beads is 1:3:5 according to the large, medium and small sequence of the diameters.
Putting the mixture into a ball milling tank, introducing Ar atmosphere, sealing the ball milling tank, and finally putting the ball milling tank into a planetary ball mill for ball milling for 8 hours at the rotating speed of 1000 rmp.
S3, spark plasma sintering: filling the gadolinium oxysulfide powder subjected to ball milling treatment into a graphite mold, attaching a layer of graphite paper to the inner wall of the mold, then putting the sintering mold filled with the gadolinium oxysulfide powder into an SPS sintering furnace, pre-pressurizing the sintering mold in the SPS sintering furnace at 25MPa, raising the temperature to between 500 ℃ and 600 ℃ at the initial sintering rate of 10 ℃/min, and preserving the heat for 20 min; the temperature is continuously increased to 1700 ℃ and 1800 ℃, the pressure is increased to 25MPa, and the temperature is kept for 30 min.
S4, cooling treatment after sintering: and after the sintering and heat preservation are finished, cooling at the cooling rate of 10 ℃/min until the temperature is cooled to room temperature to obtain the gadolinium oxysulfide scintillating ceramic sintered body.
S5, annealing treatment: the sintered body obtained in the above step is subjected to a simple treatment. Firstly removing impurities of boron nitride and graphite paper attached to the surface, then polishing a gadolinium oxysulfide sintered body, and finally annealing the polished gadolinium oxysulfide sintered body for 2 hours at 1000 ℃ in an Ar atmosphere in a muffle furnace.
And carrying out coarse grinding, fine grinding, cutting and polishing on the annealed sample to obtain the gadolinium oxysulfide scintillating ceramic.
Example 6
The preparation method of the gadolinium oxysulfide scintillating ceramic of the embodiment comprises the following steps:
s1, mixing the raw materials: 200g of commercial Gd having a purity of 99.999% and a median particle size of 3 μm were weighed2O2Pr, Ce scintillating ceramic powder, 3g Li2GeF6And (3) a sintering aid.
S2, ball milling treatment: the ball-material ratio is 9: 1; the ball milling treatment used zirconia beads, and the zirconia beads were selected as in example 5, the raw materials were placed in a ball milling jar, and Ar atmosphere was introduced, the ball milling jar was closed, and finally the ball milling jar was placed in a planetary ball mill, and ball milling was carried out for 36 hours at a rotation speed of 800 rmp.
S3, spark plasma sintering: loading the gadolinium oxysulfide powder subjected to ball milling treatment into a graphite mold, attaching a layer of graphite paper to the inner wall of the graphite mold, then placing the sintering mold filled with the gadolinium oxysulfide powder into an SPS sintering furnace, pre-pressurizing the sintering mold in the SPS sintering furnace at 15MPa, raising the temperature to between 800 ℃ and 1000 ℃ at the initial sintering heating rate of 50 ℃/min, and preserving the heat for 10 min; the temperature is continuously increased to 1300 ℃, the pressure is increased to 35MPa, and the temperature is kept for 60 min.
S4, cooling treatment after sintering: and after the sintering and heat preservation are finished, cooling at the cooling rate of 20 ℃/min until the temperature is cooled to room temperature to obtain the gadolinium oxysulfide scintillating ceramic sintered body.
S5, annealing treatment: the sintered body obtained in the above step is subjected to a simple treatment. Firstly removing impurities of boron nitride and graphite paper attached to the surface, then polishing a gadolinium oxysulfide sintered body, and finally annealing the polished gadolinium oxysulfide sintered body for 2 hours at 1100 ℃ in a muffle furnace in Ar atmosphere.
And carrying out coarse grinding, fine grinding, cutting and polishing on the annealed sample to obtain the gadolinium oxysulfide scintillating ceramic.
Example 7
The preparation method of the gadolinium oxysulfide scintillating ceramic of the embodiment comprises the following steps:
s1, mixing the raw materials: 200g of commercial Gd having a purity of 99.999% and a median particle size of 8 μm were weighed2O2Pr, Ce scintillating ceramic powder, 0.2g LiF sintering aid is added.
S2, ball milling treatment: the ball-material ratio is 3:1, zirconia beads are used for ball milling treatment, the zirconia beads are selected according to example 5, the raw materials are placed into a ball milling tank, Ar atmosphere is introduced, the ball milling tank is sealed, and finally the ball milling tank is placed into a planetary ball mill for ball milling for 12 hours at the rotating speed of 800 rmp.
S3, spark plasma sintering: filling the gadolinium oxysulfide powder subjected to ball milling treatment into a graphite mold, attaching a layer of graphite paper to the inner wall of the mold, then putting the sintering mold filled with the gadolinium oxysulfide powder into an SPS sintering furnace, pre-pressurizing the sintering mold in the SPS sintering furnace to 20MPa, raising the temperature to 600-plus-one temperature within 700 ℃ at the initial sintering rate of 100 ℃/min, and preserving the heat for 15 min; the temperature is continuously increased to 1600 ℃ and 1800 ℃, the pressure is increased to 45MPa, and the temperature is kept for 40 min.
S4, cooling treatment after sintering: and after the sintering and heat preservation are finished, cooling at the cooling rate of 30 ℃/min until the temperature is cooled to room temperature to obtain the gadolinium oxysulfide scintillating ceramic sintered body.
S5, annealing treatment: the sintered body obtained in the above step is subjected to a simple treatment. Firstly removing impurities of boron nitride and graphite paper attached to the surface, then polishing a gadolinium oxysulfide sintered body, and finally annealing the polished gadolinium oxysulfide sintered body for 3 hours at 1000 ℃ in an Ar atmosphere in a muffle furnace.
And carrying out coarse grinding, fine grinding, cutting and polishing on the annealed sample to obtain the gadolinium oxysulfide scintillating ceramic.
Example 8
The preparation method of the gadolinium oxysulfide scintillating ceramic of the embodiment comprises the following steps:
s1, mixing the raw materials: 200g of commercial Gd having a purity of 99.999% and a median particle size of 15 μm were weighed2O2Pr, Ce scintillating ceramic powder, 0.5g Li is added2GeF6And (3) a sintering aid.
S2, ball milling treatment: the ball-material ratio is 2:1, zirconia beads are used for ball milling treatment, the zirconia beads are selected according to example 5, the raw materials are placed into a ball milling tank, Ar atmosphere is introduced, the ball milling tank is sealed, and finally the ball milling tank is placed into a planetary ball mill for ball milling for 15 hours at the rotating speed of 800 rmp.
S3, spark plasma sintering: filling the gadolinium oxysulfide powder subjected to ball milling treatment into a graphite mold, attaching a layer of graphite paper to the inner wall of the mold, then putting the sintering mold filled with the gadolinium oxysulfide powder into an SPS sintering furnace, pre-pressurizing the sintering mold in the SPS sintering furnace at 20MPa, raising the temperature to 600-700 ℃ at the initial sintering rate per minute, and preserving the heat for 10 minutes; the temperature is continuously increased to 1700-1900 ℃, the pressure is increased to 40MPa, and the temperature is kept for 40 min.
S4, cooling treatment after sintering: and after the sintering and heat preservation are finished, cooling at the cooling rate of 10 ℃/min until the temperature is cooled to room temperature to obtain the gadolinium oxysulfide scintillating ceramic sintered body.
S5, annealing treatment: the sintered body obtained in the above step is subjected to a simple treatment. Firstly removing impurities of boron nitride and graphite paper attached to the surface, then polishing a gadolinium oxysulfide sintered body, and finally annealing the polished gadolinium oxysulfide sintered body for 2 hours at 1100 ℃ in a muffle furnace in Ar atmosphere.
And carrying out coarse grinding, fine grinding, cutting and polishing on the annealed sample to obtain the gadolinium oxysulfide scintillating ceramic.
In the methods of the embodiments 5 to 8, the production process shown in fig. 2 is used, and the sintered high-density gadolinium oxysulfide scintillating ceramic is sintered by a discharge plasma method (SPS), so that the preparation of the high-efficiency high-density GOS scintillating ceramic can be realized in one step. The discharge plasma sintering process can load metal powder into a graphite die, and the GOS scintillating ceramic is quickly prepared at low temperature and in short time under the conditions of low voltage and high current through discharge activation, thermoplastic deformation and cooling, and the obtained ceramic has the advantages of high density and fine and uniform crystal grains. The density of the gadolinium oxysulfide scintillating ceramic prepared by the methods of the detection examples 5-8 is within 96.9-99.2%.
It should be understood that the above examples are only for clearly illustrating the technical solutions of the present invention, and are not intended to limit the embodiments of the present invention. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. Any modification, equivalent replacement, and improvement made within the spirit and principle of the present invention should be included in the protection scope of the claims of the present invention.
Claims (10)
1. The preparation method of the gadolinium oxysulfide scintillating ceramic is characterized by comprising the following steps of:
s1, mixing the raw materials: adding a sintering aid into the gadolinium oxysulfide powder and uniformly mixing;
s2, ball milling treatment: ball milling to obtain uniform powder;
s3, one-step sintering treatment: performing vacuum sintering or spark plasma sintering on the powder subjected to ball milling treatment in the step S2;
wherein, the vacuum sintering comprises the following steps: the powder is loaded in a vacuum hot pressing furnace, the temperature rising rate of initial sintering is 5-50 ℃/min, the pressure is 25-100MPa, the temperature is 800-; continuously heating, sintering at the heating rate of 5-20 ℃/min, 45-200 MPa and 1800 ℃ at 1000 ℃ and keeping the temperature for 1-3 h;
the discharge plasma sintering is as follows: putting the powder into a sintering mold of an SPS method, putting the powder into a furnace for pre-pressurizing at 15-25MPa, raising the temperature to 500-100 ℃/min, keeping the temperature for 10-20min, continuing raising the temperature to 1800 ℃ and keeping the temperature at 25-45MPa, and keeping the temperature for 0.5-1 h;
s4, cooling treatment after sintering: cooling the sintered powder to room temperature;
s5, annealing treatment: annealing at 800-1200 ℃ to obtain the gadolinium oxysulfide scintillating ceramic blank.
2. The method for preparing gadolinium oxysulfide scintillating ceramic according to claim 1, wherein in step S1, the sintering aid is LiF or Li2GeF6(ii) a The addition amount of the sintering aid is 0.05-1.5% of that of the gadolinium oxysulfide powder.
3. The method for preparing gadolinium oxysulfide scintillating ceramic according to claim 2, characterized in that the gadolinium oxysulfide powder has a median particle size of 3-20 μm.
4. The method for preparing gadolinium oxysulfide scintillating ceramic according to claim 1, wherein in step S2, the ball-milling has a ball-to-material ratio of 2-10: 1; the ball milling is carried out under the protection condition; the ball milling time is 8-36 h.
5. The method for preparing gadolinium oxysulfide scintillating ceramic according to claim 4, characterized in that the protective condition of the ball milling treatment is absolute ethyl alcohol or Ar atmosphere.
6. The method for preparing a gadolinium oxysulfide scintillating ceramic according to claim 1, characterized in that the annealing treatment is performed in an Ar atmosphere.
7. The method for preparing gadolinium oxysulfide scintillating ceramic according to claim 1, wherein the purity of the gadolinium oxysulfide powder is 99.995% or more.
8. The method for preparing gadolinium oxysulfide scintillating ceramic according to claim 1, characterized in that, after the vacuum sintering in step S3, when the temperature in the furnace is higher than 1300 ℃, the temperature is reduced to 800-1300 ℃ at a cooling rate of 10-50 ℃/min; and cooling at the cooling rate of 10-20 ℃/min until the temperature is cooled to room temperature to obtain the gadolinium oxysulfide scintillating ceramic sintered body.
9. The method for preparing gadolinium oxysulfide scintillating ceramic according to claim 1, characterized in that, after the discharge plasma sintering of step S3, the gadolinium oxysulfide scintillating ceramic sintered body is obtained at a cooling rate of 10-20 ℃/min until the temperature is cooled to room temperature, and the high-density gadolinium oxysulfide scintillating ceramic sintered body is obtained.
10. The application of the gadolinium oxysulfide scintillating ceramic prepared by the preparation method of the gadolinium oxysulfide scintillating ceramic of any one of claims 1 to 9 in the fields of X-ray detectors, fluorescent screens, security check machines, nondestructive testing, gadolinium oxysulfide fluorescent screens in DR detectors and computed tomography imaging.
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| CN114773084A (en) * | 2022-03-21 | 2022-07-22 | 中国船舶重工集团公司第七二五研究所 | Method for preparing gadolinium oxysulfide ceramic hollow microspheres |
| CN114854414A (en) * | 2022-05-06 | 2022-08-05 | 江门市科恒实业股份有限公司 | Preparation method of Gadolinium Oxysulfide (GOS) fluorescent powder |
| CN118164519A (en) * | 2024-05-14 | 2024-06-11 | 内蒙古中科宏特高新科技有限责任公司 | High-purity rare earth oxysulfide crystal and preparation method thereof |
| CN118164519B (en) * | 2024-05-14 | 2024-09-13 | 内蒙古中科宏特高新科技有限责任公司 | High-purity rare earth oxysulfide crystal and preparation method thereof |
| CN118732011A (en) * | 2024-09-04 | 2024-10-01 | 奕瑞新材料科技（太仓）有限公司 | Resin scintillator, preparation method thereof and application thereof in radiation detector |
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Application publication date: 20220211 |