CN100431084C - Method for synthesizing thermionic emission materials - Google Patents
Method for synthesizing thermionic emission materials Download PDFInfo
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- CN100431084C CN100431084C CNB2005100118945A CN200510011894A CN100431084C CN 100431084 C CN100431084 C CN 100431084C CN B2005100118945 A CNB2005100118945 A CN B2005100118945A CN 200510011894 A CN200510011894 A CN 200510011894A CN 100431084 C CN100431084 C CN 100431084C
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Abstract
The present invention relates to a method for synthesizing thermionic emission materials, which relates to the technology of an electron tube. The present invention particularly relates to a new process for synthesizing oxide cathode thermionic emission materials by adopting gas-liquid synthetic technique, so that the emission current density of the oxide cathode is enhanced, the working temperature of the cathode is reduced, and the service life of the cathode is prolonged. The multiple carbonate is synthesized by the gas-liquid synthetic technique by the present invention, the crystallization of the synthetic carbonate is small, and the shape is in a filamentary structure. The purity is high, the technological process is small, and some technique difficulties existing in the liquid-liquid synthesis of the carbonate are avoided. The present invention which is convenient for realizing commercial process has the advantages of simple and direct process, convenient operation and high rate of finished products.
Description
Technical field
The present invention relates to electric vacuum technology, particularly relate to and adopt solution-air to be combined to technology synthesis oxide cathode primary electron emission material, and then realize improving the emission of oxide coated cathode, reduce the negative electrode working temperature, prolong a kind of new technology of cathode life.
Background technology
Oxide coated cathode is to be applied to electron tube one of hot cathode the most widely.In Investigation of Oxide Coated Cathodes, electronic emission material generally all adopts the liquid-liquid phase synthetic method synthetic, promptly with the synthetic water-fast alkaline earth metal carbonate of the nitrate generation chemical reaction of carbonate soluble in water and alkaline-earth metal, the compound that this synthesis mode participates in reaction is many, synthetic product will repeatedly wash (generally needing washing more than 7) usually, just can reach certain purity (brium carbonate, strontium carbonate, calcium carbonate content is greater than 99.9%), and along with the increase of washing times, the productive rate of synthetic product reduces, and the fastest of strontium carbonate loss found in experiment, cause brium carbonate in the product, strontium carbonate, the calcium carbonate proportion imbalance, influence the emitting performance of carbonate, grasp so the traditional preparation process technology of oxide coated cathode emissive material is difficult.
Summary of the invention
In order to overcome liquid-liquid phase carbonate synthesis salt technology complexity, technical difficulty is big, and productive rate is low, the shortcomings such as imbalance of each composition ratio of carbonate in the product, and the present invention adopts solution-air to be combined to the synthetic polynary carbonate of technology, has realized the carbonate of the synthetic high emission performance of simple and direct technology.Be used to prepare that oxide coated cathode direct current emission current is big, low temperature draws characteristics such as the big electric current life-span is long.
For achieving the above object, technical solution of the present invention provides a kind of method for synthesizing thermionic emission materials, is used for the synthetic of oxide coated cathode thermionic emission materials, and it adopts solution-air to be combined to the synthetic thermionic emission materials of technology; It comprises the following steps:
A. at first with 99.9% Ba (OH)
2, Ca (OH)
2, Sr (OH)
2(45～58) in molar ratio: (35～50): after mix (3～8), be dissolved in 50 ℃～90 ℃ the deionized water;
B. feed CO from the solution bottom then
2Gas detects the pH value of solution simultaneously, when the solution pH value is 7 ± 0.1, stops ventilation;
C. adopt acidproof filter tunnel to cross moisture in the elimination solution again;
D. at last sediment is dried under 200 ℃～250 ℃ temperature conditions, finish the synthetic of carbonate.
Described method, its described b) in the step, its Ventilation Rate is 2～3L/min, guarantees that gas feeds from the solution bottom all the time in venting process.
Described method, its described d) in the step, the time that sediment is dried, be 〉=5 hours under 200 ℃～250 ℃ temperature conditions.
Described method, its described b) in the step, adopt CO
2With Ba (OH)
2, Ca (OH)
2, Sr (OH)
2Chemical reaction takes place generate BaCO
3, CaCO
3, SrCO
3
Described method, its described d) in the step, last resulting carbonate pattern is the filament shape.
Described method, its resulting carbonate is used to improve the emitting performance of oxide coated cathode, its negative electrode direct current emission is big, when low temperature is drawn high current density the life-span long, be convenient to suitability for industrialized production.
The invention has the beneficial effects as follows, can avoid carbonate technical difficulty in liquid-liquid phase is synthetic big, a series of technical difficulties such as complex process, realized the carbonate of the synthetic high emission performance of simple and direct technology, and adopt the carbonate of this mode synthetic filament shape structure, crystal grain than liquid-liquid phase carbonate synthesis salt is little, when cathode emission surface carbon hydrochlorate grain size number reduces, atom in most of crystal grain all concentrates on the crystal grain boundary, be easy to the transmission of electronics in the cathode, thereby improve the cathode emission ability.
Description of drawings
Fig. 1 carbonate synthesis salt of the present invention shape appearance figure (2800X);
The negative electrode dc voltage current characteristic curve chart of Fig. 2 carbonate synthesis salt;
The cathode life curve chart of Fig. 3 carbonate synthesis salt.
Embodiment
Specific embodiment of the present invention is:
At first with 99.9% Ba (OH)
2, Ca (OH)
2, Sr (OH)
2After mixing in 50: 44: 6 in molar ratio, be dissolved in 70 ℃ the deionized water, feed CO then
2, its Ventilation Rate is 2.5L/min, guarantees that gas feeds from the solution bottom in venting process, the pH value of solution becomes neutrality from alkalescence gradually, when the solution pH value is 7 ± 0.1, stops the body of ventilating.Adopt acidproof filtration funnel to cross moisture in the elimination solution, sediment is dried (needing more than 5 hours) under 200 ℃ of temperature conditions, finishes the synthetic of carbonate.The pattern of the carbonate that the inventive method is synthetic as shown in Figure 1, as can be seen from the figure, the carbonate synthetic with solution-air phase method is thread, filament length 5-8 μ m, silk footpath 1-2 μ m, littler than the crystallization of adopting the synthetic carbonate of traditional liquid-liquid phase mode.
Calculate carbonate yield, analyze carbonate purity, pattern, obtain good result, the carbonate synthesis purity salt is more than 99.9%, and productive rate is more than 99%, and crystallization is little; Get 20 gram adding solvents and bonding agent and be mixed with the carbonate slurry, be sprayed at storage type oxide coated cathode emitting surface, negative electrode decomposition, activation, ageing carry out DC test and life test after 30 hours.
The filament shape carbonate that makes with the inventive method, the direct current emitting performance of preparation oxide coated cathode and the life curve figure that low temperature is drawn big electric current are respectively as Fig. 2, (conventional test diode shown in Figure 3, negative electrode diameter 3mm, between the anode and cathode apart from 0.9mm～1.1mm).As can be seen from Figure 2, negative electrode is under 850 ℃, 800 ℃ working temperatures, and direct current is launched greater than 2.8A/cm
2, in the time of 750 ℃, direct current is launched greater than 2.3A/cm
2As can be seen from Figure 3, negative electrode is drawn initial direct current emission current 1.75A/cm in the time of 800 ℃
2, within 1500 hours life-spans, the cathode emission electric current does not obviously reduce, and illustrates that negative electrode kept initial activity constant within 1500 hours, and after 3300 hours life-spans, emission current is reduced to 80% of initial transmissions electric current, end-of-life gradually.
Claims (5)
1, a kind of method for synthesizing thermionic emission materials is used for the synthetic of oxide coated cathode thermionic emission materials, it is characterized in that, adopts solution-air to be combined to the synthetic thermionic emission materials of technology; It comprises the following steps:
A. at first with 99.9% Ba (OH)
2, Ca (OH)
2, Sr (OH)
2(45～58) in molar ratio: (35～50): after mix (3～8), be dissolved in 50 ℃～90 ℃ the deionized water;
B. feed CO from the solution bottom then
2Gas detects the pH value of solution simultaneously, when the solution pH value is 7 ± 0.1, stops ventilation;
C. adopt acidproof filter tunnel to cross moisture in the elimination solution again;
D. at last sediment is dried under 200 ℃～250 ℃ temperature conditions, finish the synthetic of carbonate.
2, the method for claim 1 is characterized in that, described b) in the step, its Ventilation Rate is 2～3L/min, guarantees that gas feeds from the solution bottom all the time in venting process.
3, the method for claim 1 is characterized in that, described d) in the step, the time that sediment is dried under 200 ℃～250 ℃ temperature conditions is 〉=5 hours.
4, the method for claim 1 is characterized in that, described b) in the step, adopt CO
2With Ba (OH)
2, Ca (OH)
2, Sr (OH)
2Chemical reaction takes place generate BaCO
3, CaCO
3, SrCO
3
5, the method for claim 1 is characterized in that, described d) in the step, last resulting carbonate pattern is the filament shape.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB2005100118945A CN100431084C (en) | 2005-06-09 | 2005-06-09 | Method for synthesizing thermionic emission materials |
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|---|---|---|---|
| CNB2005100118945A CN100431084C (en) | 2005-06-09 | 2005-06-09 | Method for synthesizing thermionic emission materials |
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| CN1877773A CN1877773A (en) | 2006-12-13 |
| CN100431084C true CN100431084C (en) | 2008-11-05 |
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Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN101779265B (en) * | 2007-07-24 | 2013-01-02 | 皇家飞利浦电子股份有限公司 | Thermionic electron emitter, method for preparing same and x-ray source including same |
| CN102234126A (en) * | 2010-05-07 | 2011-11-09 | 中国科学院电子学研究所 | Synthesizing method of nano-sized granular barium carbonate, strontium carbonate, and calcium carbonate ternary salt |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2161472A (en) * | 1984-07-12 | 1986-01-15 | Murata Manufacturing Co | Preparing particulate ceramic materials |
| CN1159067A (en) * | 1995-09-21 | 1997-09-10 | 松下电子工业株式会社 | Emitter material for cathode-ray tube and manufacturing method thereof |
| CN1183168A (en) * | 1996-02-29 | 1998-05-27 | 松下电子工业株式会社 | Electron-tube cathode |
| CN1362360A (en) * | 2002-01-25 | 2002-08-07 | 彩虹彩色显像管总厂 | Production process of quarternary carbonate powder |
| US6648551B1 (en) * | 1997-02-21 | 2003-11-18 | Earth Systems Pty Ltd. | Method for stabilizing and reducing permeability of geologic or waste materials |
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2005
- 2005-06-09 CN CNB2005100118945A patent/CN100431084C/en not_active Expired - Fee Related
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2161472A (en) * | 1984-07-12 | 1986-01-15 | Murata Manufacturing Co | Preparing particulate ceramic materials |
| CN1159067A (en) * | 1995-09-21 | 1997-09-10 | 松下电子工业株式会社 | Emitter material for cathode-ray tube and manufacturing method thereof |
| CN1183168A (en) * | 1996-02-29 | 1998-05-27 | 松下电子工业株式会社 | Electron-tube cathode |
| US6648551B1 (en) * | 1997-02-21 | 2003-11-18 | Earth Systems Pty Ltd. | Method for stabilizing and reducing permeability of geologic or waste materials |
| CN1362360A (en) * | 2002-01-25 | 2002-08-07 | 彩虹彩色显像管总厂 | Production process of quarternary carbonate powder |
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Granted publication date: 20081105 Termination date: 20120609 |