CN1693284A - Electronic emitting material of molybdenum rare earth containing cerium and preparation process thereof - Google Patents
Electronic emitting material of molybdenum rare earth containing cerium and preparation process thereof Download PDFInfo
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- CN1693284A CN1693284A CN 200510077234 CN200510077234A CN1693284A CN 1693284 A CN1693284 A CN 1693284A CN 200510077234 CN200510077234 CN 200510077234 CN 200510077234 A CN200510077234 A CN 200510077234A CN 1693284 A CN1693284 A CN 1693284A
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- rare earth
- molybdenum
- emitting material
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Abstract
A Ce contained Re-Mo material as cathode for emitting electrons contains proportionally Ce2O3 or Ce2O3 plus Y2O3 and Mo. Its preparing process includes such steps as proportionally adding the aqueous solution of RE nitrate to the aqueous solution of ammonium polybdate, adding solution of citric acid, heating by water bath, baking to become gel, removing C and N at 500-550 deg.C, two-step reducing in H2 to obtain Mo powder, and powder metallurgy.
Description
Technical field
A kind of electronic emitting material of molybdenum rare earth that contains cerium and preparation method thereof belongs to rare earth refractory metal cathode material technical field.
Background technology
That use in high power valve and magnetron at present mainly is ThO
2Negative electrode (is respectively ThO
2-W hot cathode and ThO
2-W cermet negative electrode and ThO
2Refractory metal cavernous body negative electrode), but because Th is a kind of radioactive element, and its half-life is very long, in the preparation process of the production of material and negative electrode, can to human body and environment harm, therefore require the new material substitution of development.In the past, people once developed rare earth molybdenum hot cathode and the secondary emitting material that contains lanthanum
[1-2],[1] is Wang Jinshu, Zhou Meiling, Zhang Jiuxing etc., La
2O
3-Mo cathode surface carburization zone study on mechanism, Acta Metallurgica Sinica, 11 (2000) 1205-1208.[2] be Wang Jinshu, Liu Juan, Zhou Meiling etc., La
2O
3, Y
2O
3The research of-Mo secondary emitting material, China rare earth journal, 1 (2003) 23-26.
In the electron tube of certain model and magnetron, can meet the demands.But because the restriction of its heat emission and secondary emission level, can't satisfy electron tube with higher emission of cathode ability and the instructions for use of magnetron, therefore still need develop new cathode material.
Summary of the invention
The invention provides a kind of rare earth molybdenum cathode material that contains cerium, it have emitting performance good, be easy to machining characteristics.Do not see at present the report of relevant this kind investigation of materials.
The electronic emitting material of molybdenum rare earth that contains cerium provided by the present invention is characterized in that: contain Ce
2O
3A kind of or Ce
2O
3, Y
2O
3The combination of two kinds of rare earth oxides, above-mentioned rare earth oxide accounts for the 4-30% of emissive material gross weight, and all the other are molybdenum.
The preparation method who contains the electronic emitting material of molybdenum rare earth of cerium provided by the present invention is characterized in that, may further comprise the steps:
(1) with the ammonium molybdate is raw material, in ammonium molybdate aqueous solution, add rare earth nitrate aqueous solution, ammonium molybdate and rare earth nitrate consumption are by in the final rare earth molybdenum powder that obtains, rare earth oxide accounts for rare earth molybdenum powder total mass 4-30%wt, add citric acid solution then, place 60-90 ℃ of water-bath to forming colloidal sol, form gel in 100-150 ℃ of oven dry then;
(2) with this gel under 500-550 ℃, air atmosphere, decompose to till the C and N element in whole removal colloids;
(3) powder after will decomposing reduces under hydrogen atmosphere, is divided into for two steps to carry out, and the first step is 500-550 ℃, is incubated 2-4 hour; The second step reduction temperature is 900-1000 ℃, and the time is 1-2 hour, obtains the rare earth molybdenum powder, prepares electronic emitting material of molybdenum of the present invention with powder metallurgy process then.
The cathode material that contains cerium of the present invention, its secondary emission coefficient is higher than the cathode material that contains lanthanum.Simultaneously, the activationary temperature that contains cerium negative electrode maximum secondary emissivity factor correspondence is lower than the best activationary temperature that contains the lanthanum cathode material.
Description of drawings:
Fig. 1: 4wt%Ce
2O
3The LogU-LogI curve of-Mo material (embodiment 1)
Fig. 2: 30wt% (Ce
2O
3-Y
2O
3)-Mo (Ce
2O
3: Y
2O
3=1: 3, mass ratio) the secondary emission performance curve of material (embodiment 2)
Fig. 3: 30wt% (Ce
2O
3-Y
2O
3)-Mo (Ce
2O
3: Y
2O
3=1: 2, mass ratio) the secondary emission performance curve of material (embodiment 3)
Fig. 4: 30wt% (Ce
2O
3-Y
2O
3)-Mo (Ce
2O
3: Y
2O
3=2: 1, mass ratio) the secondary emission performance curve of material (embodiment 4)
Embodiment
Example 1, with 9.985 the gram cerous nitrates, 176.698 it is respectively soluble in water that gram ammonium molybdate, 100 restrains citric acids, then cerous nitrate solution and ammonium molybdate solution are mixed, precipitation appears, citric acid solution is slowly added, the precipitation gradually the dissolving, with this mixed solution in 60 ℃ of heating water baths until solution becomes colloidal sol.Colloid in 150 ℃ of oven dry, is decomposed powder to remove C and the N element in the colloid down air atmosphere, 550 ℃.In 550 ℃ hydrogen furnace, be incubated 4h, then temperature risen to 900 ℃ of insulations 1 hour, will handle the doped Ce O that obtains through reduction
2(CeO
2Content is 4%wt) molybdenum powder, adopt powder metallurgy process, make rare earth molybdenum sintered compact with certain size.After machining, make the rare earth molybdenum sheet material of φ 3 * 1mm, it is embedded in the active C powder, the following 1600 ℃ of carbonizing treatment of hydrogen atmosphere are made carbonization rare earth molybdenum hot-cathode.Adopt then method of laser welding that carbonization rare earth molybdenum sheet and molybdenum tube, the metal tungsten wire that is used for heating are welded, through exhaust, activate and make rare earth molybdenum experiment electron tube after processing.Process through activated at, the emission properties of negative electrode is seen Fig. 1, table 1 under the test different temperatures.
Example 2, with 18.9221 the gram cerous nitrates, 63.4676 gram Yttrium trinitrate, 128.7938 it is soluble in water respectively that gram ammonium molybdate, 100 restrains citric acids, then cerous nitrate, Yttrium trinitrate and ammonium molybdate solution are mixed, citric acid solution is slowly added, this mixing solutions is become colloidal sol in 80 ℃ of heating in water bath until solution.Colloid in 120 ℃ of oven dry, is decomposed powder to remove C and the N element in the colloid down air atmosphere, 500 ℃.In 500 ℃ hydrogen furnace, be incubated 3h, then temperature risen to 950 ℃ of insulations 2 hours, will process the doped Ce that obtains through reduction
2O
3And Y
2O
3(Ce
2O
3And Y
2O
3Total amount is 30%wt, wherein Ce
2O
3: Y
2O
3=1: 3, mass ratio) molybdenum powder adopts powder metallurgy process, makes the rare earth molybdenum sintered body with certain size.After machining, make the rare earth molybdenum sheet material of φ 10 * 1.5mm.Adopt then method of laser welding that rare earth molybdenum sheet and molybdenum tube, the metal tungsten wire that is used for heating are welded, through exhaust, activate and make rare earth molybdenum experiment magnetron after processing.Measure the secondary emission coefficients of processing, testing through different activationary temperatures under 600 ℃, see Fig. 2, the maximum secondary emission ratio under the best activationary temperature sees Table 2.
Example 3, with 25.2295 the gram cerous nitrates, 56.4157 the gram Yttrium trinitrate, it is soluble in water respectively that 128.7938 gram ammonium molybdates, 100 restrain citric acids, then cerous nitrate, Yttrium trinitrate and ammonium molybdate solution mixed, citric acid solution is slowly added, this mixing solutions is become colloidal sol in 90 ℃ of water-baths until solution.Colloid in 100 ℃ of oven dry, is decomposed powder to remove C and the N element in the colloid down air atmosphere, 500 ℃.In 500 ℃ hydrogen furnace, be incubated 2h, then temperature risen to 1000 ℃ of insulations 1 hour, will process the doped Ce that obtains through reduction
2O
3And Y
2O
3(Ce
2O
3And Y
2O
3Total amount is 30%wt, wherein Ce
2O
3: Y
2O
3=1: 2, mass ratio) molybdenum powder adopts powder metallurgy process, makes the rare earth molybdenum sintered body with certain size.After machining, make the rare earth molybdenum sheet material of φ 10 * 1mm.Adopt then method of laser welding that rare earth molybdenum sheet and molybdenum tube, the metal tungsten wire that is used for heating are welded, through exhaust, activate and make rare earth molybdenum experiment magnetron after processing.Measure the secondary emission coefficients of processing, testing through different activationary temperatures under 600 ℃, see Fig. 3, the maximum secondary emission ratio under the best activationary temperature sees Table 2.
Example 4, with 50.4590 the gram cerous nitrates, 28.2078 the gram Yttrium trinitrate, it is soluble in water respectively that 128.7938 gram ammonium molybdates, 100 restrain citric acids, then cerous nitrate, Yttrium trinitrate and ammonium molybdate solution mixed, citric acid solution is slowly added, this mixing solutions is become colloidal sol in 90 ℃ of water-baths until solution.This mixing solutions is become colloidal sol in 80 ℃ of heating in water bath until solution.Colloid in 100 ℃ of oven dry, is decomposed powder to remove C and the N element in the colloid down air atmosphere, 500 ℃.In 500 ℃ hydrogen furnace, be incubated 1h, then temperature risen to 950 ℃ of insulations 2 hours, will process the doped Ce that obtains through reduction
2O
3And Y
2O
3(Ce
2O
3And Y
2O
3Total amount is 30%wt, wherein Ce
2O
3: Y
2O
3=2: 1, mass ratio) molybdenum powder adopts powder metallurgy process, makes the rare earth molybdenum sintered body with certain size.After machining, make the rare earth molybdenum sheet material of φ 10 * 1mm.Adopt then method of laser welding that rare earth molybdenum sheet and molybdenum tube, the metal tungsten wire that is used for heating are welded, through exhaust, activate and make rare earth molybdenum experiment magnetron after processing.Measure the secondary emission coefficients of processing, testing through different activationary temperatures under 600 ℃, see Fig. 4, the maximum secondary emission ratio under the best activationary temperature sees Table 2.With the 30% (La that contains lanthanum
2O
3-Y
2O
3The comparing data of)-Mo negative electrode sees Table 3.
The result of table 3 shows, contains the 30wt% (Ce of cerium
2O
3-Y
2O
3)-Mo cathode material (embodiment 4), its secondary emission coefficient is higher than the 30wt% (La that contains lanthanum
2O
3-Y
2O
3)-Mo cathode material.Simultaneously, contain the corresponding activationary temperature (best activationary temperature) of cerium negative electrode maximum secondary emissivity factor (4.51) and be lower than best activationary temperature 600 degree that contain the lanthanum cathode material.
Table 1 Ce
2O
3Zero field current density (the A/cm of-Mo hot cathode
2)
| Temperature (℃) | Embodiment 1 |
| 1300 | 1.59 |
| 1350 | 2.75 |
| 1450 | 4.17 |
| 1500 | 5.03 |
Table 2 Ce
2O
3-Y
2O
3The secondary emission performance of-Mo negative electrode
| Embodiment 2 | 1000 | 3.87 |
| Embodiment 3 | 1200 | 11.11 |
| Embodiment 4 | 900 | 4.51 |
Table 3, contain the La of lanthanum
2O
3-Y
2O
3-Mo and the Ce that contains cerium
2O
3-Y
2O
3-Mo cathode material (embodiment
4) secondary emission coefficient under different activationary temperatures relatively
Claims (2)
1, contains the electronic emitting material of molybdenum rare earth of cerium, it is characterized in that: contain Ce
2O
3A kind of rare earth oxide or Ce
2O
3, Y
2O
3The combination of two kinds of rare earth oxides, above-mentioned rare earth oxide accounts for the 4-30%wt of this emissive material gross weight, and all the other are molybdenum.
2, the preparation method who contains the electronic emitting material of molybdenum rare earth of cerium according to claim 1 is characterized in that, may further comprise the steps:
Step 1: with the ammonium molybdate is raw material, in ammonium molybdate aqueous solution, add rare earth nitrate aqueous solution, ammonium molybdate and rare earth nitrate consumption are by in the final emissive material that obtains, rare earth oxide accounts for this emissive material total amount 4-30%wt, add citric acid solution then, place 60-90 ℃ of water-bath to forming colloidal sol, form gel in 100-150 ℃ of oven dry then;
Step 2: this gel under 500-550 ℃, air atmosphere, is decomposed to till the C and N element in whole removal colloids;
Step 3: the powder after will decomposing reduces under hydrogen atmosphere, be divided into two the step carry out, the first step is 500-550 ℃, is incubated 2-4 hour; The second step reduction temperature is 900-1000 ℃, and the time is 1-2 hour, obtains the rare earth molybdenum powder, prepares electronic emitting material of molybdenum of the present invention with powder metallurgy process then.
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102351248A (en) * | 2011-09-13 | 2012-02-15 | 武汉理工大学 | Method for synthesizing cerium molybdate material |
| CN112533885A (en) * | 2018-07-18 | 2021-03-19 | 国立大学法人东京工业大学 | Composite oxide ceramic, method for producing same, and article |
| CN115533112A (en) * | 2022-10-17 | 2022-12-30 | 北京工业大学 | Method for refining refractory metals by composite rare earth tungsten/molybdate eutectic |
-
2005
- 2005-06-20 CN CN 200510077234 patent/CN1290797C/en not_active Expired - Fee Related
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102351248A (en) * | 2011-09-13 | 2012-02-15 | 武汉理工大学 | Method for synthesizing cerium molybdate material |
| CN102351248B (en) * | 2011-09-13 | 2013-06-12 | 武汉理工大学 | Method for synthesizing cerium molybdate material |
| CN112533885A (en) * | 2018-07-18 | 2021-03-19 | 国立大学法人东京工业大学 | Composite oxide ceramic, method for producing same, and article |
| CN115533112A (en) * | 2022-10-17 | 2022-12-30 | 北京工业大学 | Method for refining refractory metals by composite rare earth tungsten/molybdate eutectic |
| CN115533112B (en) * | 2022-10-17 | 2023-10-20 | 北京工业大学 | Method for refining refractory metal by composite rare earth tungsten/molybdate eutectic |
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| Publication number | Publication date |
|---|---|
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