稀土钼阴极材料的微观结构与性能研究
|
摘要
本论文在课题组前期研究的基础上对稀土钼阴极发射材料进行了更为深入
的研究 用一种新的方法 溶胶凝胶法制备了多种稀土钼粉末材料 并与液固
掺杂法制备的稀土钼粉末材料相比较 探索和改进了制备的工艺 采用冷等静压
压制 氢气气氛烧结方法制成了稀土钼热发射和次级发射体材料 测试了其热发
射及次级发射性能 利用 TG-DTA XRD SEM AES 和激光粒度测试仪研究了材料
的成分 微观形貌 粒度分布 表面分析 并与用传统液固掺杂法制备的材料进
行了发射性能的比较 对稀土钼次级发射材料的发射机理进行了初步的探讨 提
出了一种稀土钼次级阴极电子输运的理论模型 研究了材料的结构与次级发射性
能之间的关系
研究结果表明 溶胶凝胶法制备的稀土钼粉末颗粒较传统液固方法制备的颗
粒细小 平均粒径约为 100nm 稀土氧化物可与碳化钼反应生成单质钼 稀土种
类不同 二者的反应温度不同
用溶胶凝胶法制备的稀土钼热阴极材料具有良好的热发射性能 其中碳化
La-Mo 阴极 1500
时的电流发射密度可达到 7.96A/cm2 通过对它们的微观结构
的研究发现 溶胶凝胶法制备的烧结体材料中稀土分布及大小更加均匀 颗粒基
本在 80nm 左右 这种均匀弥散分布的细小稀土粒子更容易在阴极体内扩散和补
充 同时发现碳化的 La-Mo 阴极具有优良的抗暴露大气的性能
稀土氧化物在空气中的稳定性与其种类有关 其中 La2O3稳定性最差 及易
与空气中的 H2O 和 CO2反应生成复杂稀土化合物 稀土氧化物可与碳化钼反应生
成单质钼 稀土种类不同 二者的反应温度不同
溶胶凝胶法制备的稀土钼次级阴极材料也具有良好的次级发射性能 其中
Y-Mo 次级阴极的最大次级发射系数达到 2.63 比传统液固方法制备的 Y-Mo 阴极
的次级发射的发射系数有了很大的提高 满足了磁控管对阴极材料的次级发射系
数 2.0 以上的应用要求 次级发射系数与材料表面的稀土含量有关 随着稀土含
量的增加 材料的次级发射系数有增长的趋势 另外 通过对碳化的稀土钼次级
阴极研究发现 碳化不利于次级发射
根据一系列的稀土钼次级发射现象推断稀土钼次级发射的电子输运模型为
- I -
北京工业大学工学硕士学位论文
稀土与钼共同发射电子的结果 其中自由电子有从金属向稀土补充的趋势
Based on the former study of our research group, the research on the properties
of rare earth oxide-molybdenum cathode materials was done in this paper. Twelve
kinds of rare earth oxide doped molybdenum powder were prepared for the first time
by sol-gel method. For comparison, the traditional method called as liquid-solid
doping method, was used to prepare rare earth oxide doped molybdenum powder
with the same composition. The rare earth oxide-molybdenum thermionic cathode
and secondary emission cathode were molded by isostatic press with pressure of 200
MPa/cm2 and sintered by resistance furnace under a continuous flow of hydrogen. In
addition, the thermionic and the secondary emission properties were measured,
respectively. The composition, microstructure, particle size distribution, surface
analysis and the element analysis of these body materials were studied by TG-DTA
XRD, SEM, AES and Laser particle analyzer. The rare earth oxide-molybdenum
secondary emission mechanism was discussed and a new model of electron
movement was proposed.
The results showed that the average particle diameter of the powder prepared by
sol-gel method was about 100nm, less than that made by solid- liquid doping method.
TG-DTA result showed that rare earth oxide can react with Mo2C to produce
molybdenum and the reaction temperature depends on the kinds of rare earth oxide
reactant.
The rare earth oxide doped molybdenum thermionic cathode prepared by sol-gel
method had good thermionic properties and the emission current density of the
carbonized La2O3-Mo cathode could reach 7.96A/cm2 at 1500 . The SEM
observation displays that the rare earth oxide has particles about 80nm in size and
distribute evenly in the material which is favorable for the diffusion of rare earth
from the inner to the surface to supply those evaporated from the surface. The result
also showed that the carbonized La2O3-Mo cathode had good anti-exposure to
atmosphere.
The rare earth oxide-molybdenum secondary emission cathode prepared by sol-gel
method also had the good secondary emission property. The maximum secondary
emission coefficient of Y2O3-Mo cathode was 2.63, higher than that of the cathode
prepared by solid- liquid doping method, which can meet practical magnetron
needs( >2.0). The secondary emission coefficients have relation with rare earth
oxide content. The material showed the tendency that the secondary emission
-III-
北京工业大学工学硕士学位论文
coefficients increase with the increase of the content of the rare earth oxide. The
results also suggest that carbonization retards the secondary emission of the cathode.
Based on a serial results, it can be deduced that the secondary emission of rare
earth oxide-molybdenum originate from both rare earth oxide and molybdenum, and
free electrons show the trend to move from molybdenum to rare earth.
的研究 用一种新的方法 溶胶凝胶法制备了多种稀土钼粉末材料 并与液固
掺杂法制备的稀土钼粉末材料相比较 探索和改进了制备的工艺 采用冷等静压
压制 氢气气氛烧结方法制成了稀土钼热发射和次级发射体材料 测试了其热发
射及次级发射性能 利用 TG-DTA XRD SEM AES 和激光粒度测试仪研究了材料
的成分 微观形貌 粒度分布 表面分析 并与用传统液固掺杂法制备的材料进
行了发射性能的比较 对稀土钼次级发射材料的发射机理进行了初步的探讨 提
出了一种稀土钼次级阴极电子输运的理论模型 研究了材料的结构与次级发射性
能之间的关系
研究结果表明 溶胶凝胶法制备的稀土钼粉末颗粒较传统液固方法制备的颗
粒细小 平均粒径约为 100nm 稀土氧化物可与碳化钼反应生成单质钼 稀土种
类不同 二者的反应温度不同
用溶胶凝胶法制备的稀土钼热阴极材料具有良好的热发射性能 其中碳化
La-Mo 阴极 1500
时的电流发射密度可达到 7.96A/cm2 通过对它们的微观结构
的研究发现 溶胶凝胶法制备的烧结体材料中稀土分布及大小更加均匀 颗粒基
本在 80nm 左右 这种均匀弥散分布的细小稀土粒子更容易在阴极体内扩散和补
充 同时发现碳化的 La-Mo 阴极具有优良的抗暴露大气的性能
稀土氧化物在空气中的稳定性与其种类有关 其中 La2O3稳定性最差 及易
与空气中的 H2O 和 CO2反应生成复杂稀土化合物 稀土氧化物可与碳化钼反应生
成单质钼 稀土种类不同 二者的反应温度不同
溶胶凝胶法制备的稀土钼次级阴极材料也具有良好的次级发射性能 其中
Y-Mo 次级阴极的最大次级发射系数达到 2.63 比传统液固方法制备的 Y-Mo 阴极
的次级发射的发射系数有了很大的提高 满足了磁控管对阴极材料的次级发射系
数 2.0 以上的应用要求 次级发射系数与材料表面的稀土含量有关 随着稀土含
量的增加 材料的次级发射系数有增长的趋势 另外 通过对碳化的稀土钼次级
阴极研究发现 碳化不利于次级发射
根据一系列的稀土钼次级发射现象推断稀土钼次级发射的电子输运模型为
- I -
北京工业大学工学硕士学位论文
稀土与钼共同发射电子的结果 其中自由电子有从金属向稀土补充的趋势
Based on the former study of our research group, the research on the properties
of rare earth oxide-molybdenum cathode materials was done in this paper. Twelve
kinds of rare earth oxide doped molybdenum powder were prepared for the first time
by sol-gel method. For comparison, the traditional method called as liquid-solid
doping method, was used to prepare rare earth oxide doped molybdenum powder
with the same composition. The rare earth oxide-molybdenum thermionic cathode
and secondary emission cathode were molded by isostatic press with pressure of 200
MPa/cm2 and sintered by resistance furnace under a continuous flow of hydrogen. In
addition, the thermionic and the secondary emission properties were measured,
respectively. The composition, microstructure, particle size distribution, surface
analysis and the element analysis of these body materials were studied by TG-DTA
XRD, SEM, AES and Laser particle analyzer. The rare earth oxide-molybdenum
secondary emission mechanism was discussed and a new model of electron
movement was proposed.
The results showed that the average particle diameter of the powder prepared by
sol-gel method was about 100nm, less than that made by solid- liquid doping method.
TG-DTA result showed that rare earth oxide can react with Mo2C to produce
molybdenum and the reaction temperature depends on the kinds of rare earth oxide
reactant.
The rare earth oxide doped molybdenum thermionic cathode prepared by sol-gel
method had good thermionic properties and the emission current density of the
carbonized La2O3-Mo cathode could reach 7.96A/cm2 at 1500 . The SEM
observation displays that the rare earth oxide has particles about 80nm in size and
distribute evenly in the material which is favorable for the diffusion of rare earth
from the inner to the surface to supply those evaporated from the surface. The result
also showed that the carbonized La2O3-Mo cathode had good anti-exposure to
atmosphere.
The rare earth oxide-molybdenum secondary emission cathode prepared by sol-gel
method also had the good secondary emission property. The maximum secondary
emission coefficient of Y2O3-Mo cathode was 2.63, higher than that of the cathode
prepared by solid- liquid doping method, which can meet practical magnetron
needs( >2.0). The secondary emission coefficients have relation with rare earth
oxide content. The material showed the tendency that the secondary emission
-III-
北京工业大学工学硕士学位论文
coefficients increase with the increase of the content of the rare earth oxide. The
results also suggest that carbonization retards the secondary emission of the cathode.
Based on a serial results, it can be deduced that the secondary emission of rare
earth oxide-molybdenum originate from both rare earth oxide and molybdenum, and
free electrons show the trend to move from molybdenum to rare earth.
引文
1 刘学悫.阴极电子学.科学出版社 1980 4-7
2 苏奇才 孙振红 正交场器件的光明前途 第十届学术年会军用微波管研讨会
3 廖复疆.吴固基.真空电子技术.国防工业出版社 1999
4 王金淑.李洪义等.影响稀土氧化物-钼次级阴极发射性能的元素.中国稀土学
报 2003.6:263-266.
5 WANG Jinshu.Li Hongyi et al.A study of secondary electron emission
properties of the molybdenum cathode doped with RE2O3. Applied Surface
science,2003 215:273-279.
6 刘娟.北京工业大学硕士论文 2002 6
7 刘冬梅.国际阴极发展概述.军用阴极电子源技术研讨会 2002.9.37-41
8 R.H.Fowler,Phys.Rev,38,45(1973)
9 O.Hachenberg,Adv.in Electronics and Electron Physics,VolXI:413,1959
10 J.c.Tucek,S.G.Walton,R.L.Champion., Surface Science,410 (1998):
258-269
11 徐光宪主编. 稀土 第 2 版 .冶金工业出版社 1995 315-329
12 李小琼.廖显恒.刘桂全.稀土金属化合物阴极.电子学报.1965 3 48-56
13 薛增泉.吴泉德.电子发射与光电子能谱.北京大学出版社 1992
14 J.M.Lafferty,J.Appl.Phys.,1951,22,229
15 Yada Keiji etal.,J.Electron Mocrosc Tech 12(3),1989,252
16 M.J.Albert,Brit.J.appl.Phys.,167,18,627.
17 H.E.Gallagher,IEEE Conf.Record of 1968 9thconf.On Tube Techniq.New
York,1968
18 G.Gessinger,C.Buxbaum.High.Temperature[J],1978,10:325-330
19C.Buxbaum,G.Gessinger.Lanthanated.ThermionicCathode[P].U.S.Patent40
83811,1978-04-11
20 Buxbaum C.,Gessinger G.U.S.,4019081,1977 4 19
21 Buxbaum C.U.S.,4274030,1981.6.16
- -
北京工业大学工学硕士学位论文
22 Buxbaum C. NTG Fachber, 1983,85:223-227
23 Buxbaum C.,Baden.Brown Boveri Rev.1-79.43-45
24 D.M.Goebel etal,Rev Sci Instrum,1980,51(11):1468
25Goebel.D.M.,Hirooka.Y.&.Campbell.G.A.Rev.Sci.Instrum.56(10),1985.10
26FrankB.,GartuerG.U.S.,4533852,1985.8.619P.Wargo,B.V.HaxbyandW.G.She
hered,J.Appl.Phys.,27(1956)11,1311
27 王永树.邓耀得.王奇.一种抗中毒的阴极.电子科学学刊.1983 5 1 64-65
28 王永树.邓耀得.王奇.对镧-碳化钨阴极发射大和抗油蒸汽中毒的探讨.电子
科学学刊.1986 8 4 287-292
29 冯辅义.La-Mo 阴极及其应用.真空电子材料与器件第九届学术年会论文
集.1992 1-6
30 李小琼.廖显恒.刘桂全.稀土金属化合物阴极.电子学报.1965 3 48-56
31 冯辅义.真空电子技术.1993 No.4:6-9
32Zhou.Meiling,Cheng.Zhongchun,Zhang.Jiuxin,etal.,High.TemperatureHig
h.Pressures,1994,Vol.26:145-149
33 聂祚仁等.稀土金属热阴极中的超额镧.中国稀土学报.1998 3 Vol.16.No.1
34 张久兴等.稀土钼合金力学及热发射性能的研究.稀有金属 2002 26 2
124 128
35 聂祚仁.中南工业大学博士论文. 1997.11
36 王金淑.北京工业大学博士论文 1999 2:10
37 姚草根.北京工业大学硕士学位论文. 1999.7
38H.Bruining,Physics and Applications of Secondary Electron
Emission,1954
39 E.M.Baroody,Phys.Rev,78(1950)6:780
40 O.Hachenberg,Adv.in Electronics and Electron Physics,VolXI:413,1959
41 J.c.Tucek,S.G.Walton,R.L.Champion., Surface Science,410 (1998):
258-269
42 J.c.Tucek,R.L.Champion.,Surface,Science,382(1997) 137-146
43 聂祚仁.左铁镛.周美玲等.Mo-La2O3 模拟阴极的高温 XPS/AES 研究 I,II ,
中国稀土学报,1999,17(2):135
- -
参考文献
44 聂祚仁.左铁镛.周美玲等.Mo-La2O3 阴极丝的 AES 深度剖析.稀有金属,1999:
23
45 T.Sato,,S.Kobayashi,S.Michizono,Y,Saito,Applied Surface Science,
144-145, (1999): 324-328
46 刘光华.现代材料化学.上海科学技术出版社 2000:455 484
47 Sorokina,V.M.Radiotekhnika,22:88
48 B.Ch.Djubua,O.V.Polivnikova,SRPC Istok,Fryazino, IVESC 2000,E-6
49 苏联专利 245,92527
50.张晖.显微组织细化对 W-Th02阴极性能的影响.材料研究学报 Vol14.,Suppl.
2000 19-22
51 Wang Jinsh, Liu Juan, Zhou Meiling et al. La2O3- Gd2O3-Mo secondary
emission material. [J].Tran.Nonferrous Met Soc China,2003,13(1):38
52 李洪义 北京工业大学硕士学位论文 2003.6
53 王金淑.刘娟.周美玲等.掺杂稀土氧化物钼阴极次级发射性能的研究.北京工
业大学学报 2002 28(3):374-377
54 王金淑.郑经祥.王亦曼等.稀土-钼次级发射体发射性能的研究.真空电子技
术 2002(5):22-26
55 张立德.纳米材料与纳米结构.科学出版社 2001
56 王金淑等 La-Mo 阴极材料热分析研究 北京工业大学学报 Mar.2002Vol.28
57 江剑平.翁甲辉等.阴极电子学与气体放电原理.国防工业出版社 1980
2 苏奇才 孙振红 正交场器件的光明前途 第十届学术年会军用微波管研讨会
3 廖复疆.吴固基.真空电子技术.国防工业出版社 1999
4 王金淑.李洪义等.影响稀土氧化物-钼次级阴极发射性能的元素.中国稀土学
报 2003.6:263-266.
5 WANG Jinshu.Li Hongyi et al.A study of secondary electron emission
properties of the molybdenum cathode doped with RE2O3. Applied Surface
science,2003 215:273-279.
6 刘娟.北京工业大学硕士论文 2002 6
7 刘冬梅.国际阴极发展概述.军用阴极电子源技术研讨会 2002.9.37-41
8 R.H.Fowler,Phys.Rev,38,45(1973)
9 O.Hachenberg,Adv.in Electronics and Electron Physics,VolXI:413,1959
10 J.c.Tucek,S.G.Walton,R.L.Champion., Surface Science,410 (1998):
258-269
11 徐光宪主编. 稀土 第 2 版 .冶金工业出版社 1995 315-329
12 李小琼.廖显恒.刘桂全.稀土金属化合物阴极.电子学报.1965 3 48-56
13 薛增泉.吴泉德.电子发射与光电子能谱.北京大学出版社 1992
14 J.M.Lafferty,J.Appl.Phys.,1951,22,229
15 Yada Keiji etal.,J.Electron Mocrosc Tech 12(3),1989,252
16 M.J.Albert,Brit.J.appl.Phys.,167,18,627.
17 H.E.Gallagher,IEEE Conf.Record of 1968 9thconf.On Tube Techniq.New
York,1968
18 G.Gessinger,C.Buxbaum.High.Temperature[J],1978,10:325-330
19C.Buxbaum,G.Gessinger.Lanthanated.ThermionicCathode[P].U.S.Patent40
83811,1978-04-11
20 Buxbaum C.,Gessinger G.U.S.,4019081,1977 4 19
21 Buxbaum C.U.S.,4274030,1981.6.16
- -
北京工业大学工学硕士学位论文
22 Buxbaum C. NTG Fachber, 1983,85:223-227
23 Buxbaum C.,Baden.Brown Boveri Rev.1-79.43-45
24 D.M.Goebel etal,Rev Sci Instrum,1980,51(11):1468
25Goebel.D.M.,Hirooka.Y.&.Campbell.G.A.Rev.Sci.Instrum.56(10),1985.10
26FrankB.,GartuerG.U.S.,4533852,1985.8.619P.Wargo,B.V.HaxbyandW.G.She
hered,J.Appl.Phys.,27(1956)11,1311
27 王永树.邓耀得.王奇.一种抗中毒的阴极.电子科学学刊.1983 5 1 64-65
28 王永树.邓耀得.王奇.对镧-碳化钨阴极发射大和抗油蒸汽中毒的探讨.电子
科学学刊.1986 8 4 287-292
29 冯辅义.La-Mo 阴极及其应用.真空电子材料与器件第九届学术年会论文
集.1992 1-6
30 李小琼.廖显恒.刘桂全.稀土金属化合物阴极.电子学报.1965 3 48-56
31 冯辅义.真空电子技术.1993 No.4:6-9
32Zhou.Meiling,Cheng.Zhongchun,Zhang.Jiuxin,etal.,High.TemperatureHig
h.Pressures,1994,Vol.26:145-149
33 聂祚仁等.稀土金属热阴极中的超额镧.中国稀土学报.1998 3 Vol.16.No.1
34 张久兴等.稀土钼合金力学及热发射性能的研究.稀有金属 2002 26 2
124 128
35 聂祚仁.中南工业大学博士论文. 1997.11
36 王金淑.北京工业大学博士论文 1999 2:10
37 姚草根.北京工业大学硕士学位论文. 1999.7
38H.Bruining,Physics and Applications of Secondary Electron
Emission,1954
39 E.M.Baroody,Phys.Rev,78(1950)6:780
40 O.Hachenberg,Adv.in Electronics and Electron Physics,VolXI:413,1959
41 J.c.Tucek,S.G.Walton,R.L.Champion., Surface Science,410 (1998):
258-269
42 J.c.Tucek,R.L.Champion.,Surface,Science,382(1997) 137-146
43 聂祚仁.左铁镛.周美玲等.Mo-La2O3 模拟阴极的高温 XPS/AES 研究 I,II ,
中国稀土学报,1999,17(2):135
- -
参考文献
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