CN101372339A - Preparation of high purity high dense polycrystal CeB6 block cathode material - Google Patents
Preparation of high purity high dense polycrystal CeB6 block cathode material Download PDFInfo
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- CN101372339A CN101372339A CNA200810225028XA CN200810225028A CN101372339A CN 101372339 A CN101372339 A CN 101372339A CN A200810225028X A CNA200810225028X A CN A200810225028XA CN 200810225028 A CN200810225028 A CN 200810225028A CN 101372339 A CN101372339 A CN 101372339A
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Abstract
A method for preparing a high-purity and high-density polycrystalline CeB6 cathode material pertains to the technical field of rare earth boride cathode materials. The existing preparation process of the CeB6 is complicated, and the obtained sample has low purity and poor density. The method comprises the following steps: cerium hydride nano-powder is prepared by a DC arc evaporation condensation process, then the cerium hydride nano-powder and boron powder are mixed by grinding in a hypoxia environment, and sintered in vacuum or a high-purity argon atmosphere by a discharge plasma sintering technology to obtain the polycrystalline CeB6 cathode material. The method has the advantages of simple process and low sintering temperature, and that the prepared cathode material has high purity, good density, high chemical purity and excellent emission performance.
Description
Technical field
The invention belongs to rare-earth boride cathode material technical field, be specifically related to a kind of high purity high dense polycrystal CeB
6The preparation method of block cathode material.
Background technology
CeB
6Excellent properties with rare earth metal hexaboride is as the fusing point height, hardness is big, electron work functon is low, volatility is little, strong, the anti-ion bombardment ability of anti-poisoning capability is strong etc.And LaB
6The same, CeB
6Be the ideal hot cathode material, be applied in the equipment such as Electronic Speculum, plasma source, electron beam welding machine, electron beam exposure apparatus, field emission array.
Studies show that in recent years, CeB
6As hot cathode material, with the LaB that is acknowledged as best cathodes in the rare-earth boride
6Compare, have several more outstanding characteristics, the one, anti-Prevent Carbon Contamination ability is strong, and the 2nd, the rate of evaporation below 1800K compares LaB
6Low by 40%, three, LaB
6Resistivity is low, can only do cathodes heated indirectly by an el in electron beam gun, and CeB
6Resistivity is about LaB
6Four times of resistivity can be fit to make heater cathode, and CeB
6Emissive power than tungsten are a lot of by force, thereby might replace still widely used at present direet-heating type tungsten cathode.Therefore, CeB
6Have a good application prospect.
Polycrystalline Ce B
6Traditional preparation method of block was divided into for two steps: adopt fused salt electrolysis process earlier, and the hot method of boron, magnesiothermy, methods such as norbide reduction method prepare CeB
6Powder, and then adopt hot pressing or cold sintering at high temperature (more than 2000 ℃), it is long-time that (2～10h) sintering prepare polycrystalline bulk.Whole flow process will experience fragmentation, pickling, washing, oven dry and the screening of powder and long thereafter high temperature sintering, and technology is loaded down with trivial details, is difficult for grasping, and production cost is higher.And the CeB for preparing
6The purity of block is often not high, and density has only 80-92%, and crystal grain thick (tens to the hundreds of micron) had a strong impact on the emitting performance of material, has limited CeB
6Application.
Summary of the invention
The objective of the invention is to solve prior art problems, and provide that a kind of crystal grain is tiny, density is high, purity is high, mechanical property and emitting performance excellence, technology is simple, cost is low, sintering temperature is low, the polycrystalline Ce B that sintering time is short
6The preparation method of block cathode material.
The present invention prepares hydrogenation cerium (CeH by adopting the hydrogen direct current arc using vaporization condensation process
2) behind the nanometer powder, adopt discharge plasma sintering (SPS) technology sintering boron (B) powder and CeH
2Nanometer powder, preparation polycrystalline Ce B
6Block materials, concrete steps are as follows:
1) direct current arc evaporation condensing plant reaction chamber is evacuated to 1.0 * 10
-2～3.0 * 10
-3Behind the Pa, charging into volume ratio is 1～4:1, total gas pressure is 0.1Mpa, purity is 99.999% high-purity hydrogen and argon gas, with the tungsten is negative electrode, and elemental metals cerium piece is an anode, at reaction current 80～150A, arc voltage 20～45V, preparation hydrogenation cerium nanometer powder under the condition of reaction times 20～40min;
2) hydrogenation cerium nanometer powder and boron powder are lower than in the pretreatment chamber of 80ppm in oxygen level, press mass ratio 1:0.456 ground and mixed after, in the graphite jig of packing into;
3) graphite jig is put into the SPS agglomerating plant and carried out sintering, sintering process is: sintering atmosphere is vacuum or high-purity (99.999%) argon gas atmosphere of 2～10Pa, sintering pressure is 30～60MPa, sintering temperature is 1300～1700 ℃, temperature rise rate is 80～200 ℃/min, insulation is 3～20min, and furnace cooling obtains high purity high dense polycrystal CeB
6Block cathode material.
The particle diameter of the hydrogenation cerium nanometer powder wherein, step 1) and 2) is 20～60nm; The particle diameter of the boron powder step 2) is 20～50nm or 2～10 μ m.
Compared with prior art, the present invention has following beneficial effect:
1) the present invention adopts elementsynthesis to guarantee the purity of sample, and the hypoxic integrated combination of experimental system employing hydrogen direct current arc equipment and SPS device has simultaneously avoided the oxidation of nanometer powder further to improve the purity of sample;
2) the present invention adopts SPS sintering nanometer powder to significantly improve density, reduction sintering temperature, the saving sintering time of sintered compact;
3) the prepared CeB of the present invention
6The crystal grain of block sample is tiny, and purity reaches 99.86%, and relative density reaches 99.6%, and hardness reaches 1927kg/mm
2, bending strength reaches 243.7MPa.Sample emission under 1520 ℃ of temperature reaches 16.98A/cm
2, work function is 2.40eV.
Description of drawings
The polycrystalline Ce B of Fig. 1, embodiment 1 preparation
6The XRD figure spectrum of block sample.
The polycrystalline Ce B of Fig. 2, embodiment 1 preparation
6The SEM fracture photo of block sample.
The invention will be further described below in conjunction with the drawings and specific embodiments.
Embodiment
Embodiment 1
1) direct current arc evaporation condensing plant reaction chamber is evacuated to 3.0 * 10
-3Behind the Pa, charging into volume ratio is 3:1, and total gas pressure is hydrogen and the argon gas of 0.1MPa, with the tungsten is negative electrode, and elemental metals cerium piece is an anode, at reaction current 80A, arc voltage 45V, the preparation particle diameter is the hydrogenation cerium nanometer powder of 20～40nm under the condition of reaction times 20min;
2) with hydrogenation cerium nanometer powder and boron powder (20～50nm) is in the pretreatment chamber of 10ppm in oxygen level, press mass ratio 1:0.456 ground and mixed after, in the graphite jig of packing into;
3) graphite jig is put into the SPS agglomerating plant and carried out sintering, sintering process is: sintering atmosphere is the vacuum of 5Pa, and sintering pressure is 30MPa, sintering temperature is 1300 ℃, temperature rise rate is 80 ℃/min, is incubated to be 20min, and furnace cooling obtains high purity high dense polycrystal CeB
6Block cathode material.
CeB
6The block sample X ray diffracting spectrum as shown in Figure 1, be single-phase CeB
6, the well-crystallized.XRF (XRF) test shows, this CeB
6The chemical purity of sintering block sample reaches 99.87%.Fig. 2 is scanning electron microscope (SEM) the fracture photo of this sample, and photo shows the uniform crystal particles densification, and average grain size is 2 μ m.Density 99.5%, hardness reaches 1896kg/mm
2, bending strength reaches 231.3MPa.Sample emission under 1520 ℃ of temperature reaches 16.33A/cm
2, work function is 2.40eV.
1) direct current arc evaporation condensing plant reaction chamber is evacuated to 5.0 * 10
-3Behind the Pa, charging into volume ratio is 1:1, and total gas pressure is hydrogen and the argon gas of 0.1MPa, with the tungsten is negative electrode, and elemental metals cerium piece is an anode, at reaction current 150A, arc voltage 20V, the preparation particle diameter is the hydrogenation cerium nanometer powder of 30～60nm under the condition of reaction times 30min;
2) with hydrogenation cerium nanometer powder and boron powder (20～50nm) is in the pretreatment chamber of 50ppm in oxygen level, press mass ratio 1:0.456 ground and mixed after, in the graphite jig of packing into;
3) graphite jig is put into the SPS agglomerating plant and carried out sintering, sintering process is: sintering atmosphere is the vacuum of 5Pa, and sintering pressure is 50MPa, sintering temperature is 1500 ℃, temperature rise rate is 140 ℃/min, is incubated to be 12min, and furnace cooling obtains high purity high dense polycrystal CeB
6Block cathode material.
CeB
6The X ray diffracting spectrum of block sample is shown as single-phase CeB
6, the well-crystallized.XRF (XRF) test shows, this CeB
6The chemical purity of sintering block sample reaches 99.91%.Uniform crystal particles densification, average grain size are 5 μ m.Density 99.6%, hardness reaches 1927kg/mm
2, bending strength reaches 243.7MPa.Sample emission under 1520 ℃ of temperature reaches 16.98A/cm
2, work function is 2.40eV.
Embodiment 3
1) direct current arc evaporation condensing plant reaction chamber is evacuated to 1.0 * 10
-2Behind the Pa, charging into volume ratio is 4:1, and total gas pressure is hydrogen and the argon gas of 0.1MPa, with the tungsten is negative electrode, and elemental metals cerium piece is an anode, at reaction current 90A, arc voltage 30V, the preparation particle diameter is the hydrogenation cerium nanometer powder of 20～50nm under the condition of reaction times 40min;
2) be in the pretreatment chamber of 80ppm with hydrogenation cerium nanometer powder and boron powder (2～10 μ m) in oxygen level, press mass ratio 1:0.456 ground and mixed after, in the graphite jig of packing into;
3) graphite jig is put into the SPS agglomerating plant and carried out sintering, sintering process is: sintering atmosphere is that the purity of 0.1MPa is 99.999% high-purity argon gas atmosphere, sintering pressure is 60MPa, sintering temperature is 1700 ℃, temperature rise rate is 200 ℃/min, insulation is 3min, and furnace cooling obtains high purity high dense polycrystal CeB
6Block cathode material.
CeB
6The X ray diffracting spectrum of block sample is shown as single-phase CeB
6, the well-crystallized.XRF (XRF) test shows, this CeB
6The chemical purity of sintering block sample reaches 99.85%.Uniform crystal particles densification, average grain size are 30 μ m.Density 99.2%, hardness reaches 1850kg/mm
2, bending strength reaches 221.7MPa.Sample emission under 1520 ℃ of temperature reaches 15.20A/cm
2, work function is 2.41eV.
Claims (3)
1. high purity high dense polycrystal CeB
6The preparation method of block cathode material is characterized in that, may further comprise the steps:
1) direct current arc evaporation condensing plant reaction chamber is evacuated to 1.0 * 10
-2～3.0 * 10
-3Behind the Pa, charging into volume ratio is 1～4:1, total gas pressure is 0.1Mpa, purity is 99.999% high-purity hydrogen and argon gas, with the tungsten is negative electrode, and elemental metals cerium piece is an anode, at reaction current 80～150A, arc voltage 20～45V, preparation hydrogenation cerium nanometer powder under the condition of reaction times 20～40min;
2) hydrogenation cerium nanometer powder and boron powder are lower than in the pretreatment chamber of 80ppm in oxygen level, press mass ratio 1:0.456 ground and mixed after, in the graphite jig of packing into;
3) graphite jig is put into the SPS agglomerating plant and carried out sintering, sintering process is: sintering atmosphere is that the vacuum of 2～10Pa or purity are 99.999% high-purity argon gas atmosphere, sintering pressure is 30～60MPa, sintering temperature is 1300～1700 ℃, temperature rise rate is 80～200 ℃/min, insulation is 3～20min, and furnace cooling obtains high purity high dense polycrystal CeB
6Block cathode material.
2. method according to claim 1 is characterized in that, the particle diameter of described hydrogenation cerium nanometer powder is 20～60nm.
3. method according to claim 1 is characterized in that step 2) described in the particle diameter of boron powder be 20～50nm or 2～10 μ m.
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Cited By (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101983920A (en) * | 2010-11-19 | 2011-03-09 | 北京工业大学 | Preparation method of cathode material of DyB6 polycrystalline bulk |
| CN102285662A (en) * | 2011-05-25 | 2011-12-21 | 山东理工大学 | Preparation method of niobium boride powder |
| CN102433587A (en) * | 2011-09-19 | 2012-05-02 | 北京工业大学 | Preparation method of multicomponent large-size rare earth boride LaxCe1-xB6 monocrystalline block cathode material |
| CN102515769A (en) * | 2011-11-23 | 2012-06-27 | 北京工业大学 | Multi-element rare-earth boride (CexPr1-x)B6 anode material and preparation method thereof |
| CN102515116A (en) * | 2011-11-28 | 2012-06-27 | 北京工业大学 | Preparation method for high-purity tellurium nanometer powder |
| CN103601207A (en) * | 2013-11-12 | 2014-02-26 | 北京工业大学 | Preparation method of high-purity high-density YbB6 polycrystal blocky negative electrode material |
| CN104894641A (en) * | 2015-04-29 | 2015-09-09 | 井冈山大学 | High-density (LaxCa1-x)B6 polycrystalline cathode material and preparation method thereof |
| CN107342201A (en) * | 2017-07-20 | 2017-11-10 | 信阳师范学院 | A kind of CeB6The preparation method of flexible Field Emission cathode material |
| CN109665537A (en) * | 2019-02-22 | 2019-04-23 | 成都理工大学 | A kind of low temperature preparation EuB6The method of nanocube crystal |
| CN109804450A (en) * | 2016-10-13 | 2019-05-24 | 株式会社日立高新技术 | Electron beam device |
| CN109928400A (en) * | 2019-05-07 | 2019-06-25 | 吉林大学 | A kind of preparation method of the one boronation titanium block material of nano polycrystal of adhesive-free |
| CN111793823A (en) * | 2020-07-16 | 2020-10-20 | 合肥工业大学 | High-purity gadolinium hexaboride polycrystal and preparation method thereof |
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2008
- 2008-10-24 CN CNA200810225028XA patent/CN101372339A/en active Pending
Cited By (16)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101983920A (en) * | 2010-11-19 | 2011-03-09 | 北京工业大学 | Preparation method of cathode material of DyB6 polycrystalline bulk |
| CN102285662A (en) * | 2011-05-25 | 2011-12-21 | 山东理工大学 | Preparation method of niobium boride powder |
| CN102433587A (en) * | 2011-09-19 | 2012-05-02 | 北京工业大学 | Preparation method of multicomponent large-size rare earth boride LaxCe1-xB6 monocrystalline block cathode material |
| CN102433587B (en) * | 2011-09-19 | 2014-11-26 | 北京工业大学 | Preparation method of multicomponent large-size rare earth boride LaxCe1-xB6 monocrystalline block cathode material |
| CN102515769A (en) * | 2011-11-23 | 2012-06-27 | 北京工业大学 | Multi-element rare-earth boride (CexPr1-x)B6 anode material and preparation method thereof |
| CN102515116A (en) * | 2011-11-28 | 2012-06-27 | 北京工业大学 | Preparation method for high-purity tellurium nanometer powder |
| CN103601207A (en) * | 2013-11-12 | 2014-02-26 | 北京工业大学 | Preparation method of high-purity high-density YbB6 polycrystal blocky negative electrode material |
| CN104894641B (en) * | 2015-04-29 | 2017-07-14 | 井冈山大学 | It is a kind of high fine and close（LaxCa1‑x）B6Polycrystalline cathode material and preparation method thereof |
| CN104894641A (en) * | 2015-04-29 | 2015-09-09 | 井冈山大学 | High-density (LaxCa1-x)B6 polycrystalline cathode material and preparation method thereof |
| CN109804450A (en) * | 2016-10-13 | 2019-05-24 | 株式会社日立高新技术 | Electron beam device |
| CN109804450B (en) * | 2016-10-13 | 2020-12-01 | 株式会社日立高新技术 | Electron beam apparatus |
| CN107342201A (en) * | 2017-07-20 | 2017-11-10 | 信阳师范学院 | A kind of CeB6The preparation method of flexible Field Emission cathode material |
| CN109665537A (en) * | 2019-02-22 | 2019-04-23 | 成都理工大学 | A kind of low temperature preparation EuB6The method of nanocube crystal |
| CN109928400A (en) * | 2019-05-07 | 2019-06-25 | 吉林大学 | A kind of preparation method of the one boronation titanium block material of nano polycrystal of adhesive-free |
| CN109928400B (en) * | 2019-05-07 | 2022-11-04 | 吉林大学 | Preparation method of nano polycrystalline titanium boride block material without adhesive |
| CN111793823A (en) * | 2020-07-16 | 2020-10-20 | 合肥工业大学 | High-purity gadolinium hexaboride polycrystal and preparation method thereof |
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