JPH0612978A - Manufacture of tungsten powder sintered body for impregnation type cathode - Google Patents
Manufacture of tungsten powder sintered body for impregnation type cathodeInfo
- Publication number
- JPH0612978A JPH0612978A JP4190070A JP19007092A JPH0612978A JP H0612978 A JPH0612978 A JP H0612978A JP 4190070 A JP4190070 A JP 4190070A JP 19007092 A JP19007092 A JP 19007092A JP H0612978 A JPH0612978 A JP H0612978A
- Authority
- JP
- Japan
- Prior art keywords
- tungsten powder
- tungsten
- sintered body
- type cathode
- cathode
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 title claims abstract description 48
- 238000005470 impregnation Methods 0.000 title claims abstract description 6
- 238000004519 manufacturing process Methods 0.000 title claims description 12
- 238000005245 sintering Methods 0.000 claims abstract description 11
- 238000003825 pressing Methods 0.000 claims description 11
- 239000002245 particle Substances 0.000 claims description 10
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims description 4
- 239000001257 hydrogen Substances 0.000 claims description 4
- 229910052739 hydrogen Inorganic materials 0.000 claims description 4
- 238000000034 method Methods 0.000 claims description 2
- 239000013078 crystal Substances 0.000 abstract description 18
- 229910052721 tungsten Inorganic materials 0.000 abstract description 15
- 239000010937 tungsten Substances 0.000 abstract description 14
- 229910052788 barium Inorganic materials 0.000 abstract description 7
- DSAJWYNOEDNPEQ-UHFFFAOYSA-N barium atom Chemical compound [Ba] DSAJWYNOEDNPEQ-UHFFFAOYSA-N 0.000 abstract description 7
- 238000009792 diffusion process Methods 0.000 abstract description 4
- 239000011148 porous material Substances 0.000 description 6
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 description 5
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 4
- 239000011521 glass Substances 0.000 description 4
- 238000007796 conventional method Methods 0.000 description 3
- GKOZUEZYRPOHIO-UHFFFAOYSA-N iridium atom Chemical compound [Ir] GKOZUEZYRPOHIO-UHFFFAOYSA-N 0.000 description 3
- 229910052786 argon Inorganic materials 0.000 description 2
- QVQLCTNNEUAWMS-UHFFFAOYSA-N barium oxide Chemical compound [Ba]=O QVQLCTNNEUAWMS-UHFFFAOYSA-N 0.000 description 2
- 239000007789 gas Substances 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- 229910052741 iridium Inorganic materials 0.000 description 2
- 238000001953 recrystallisation Methods 0.000 description 2
- 230000002159 abnormal effect Effects 0.000 description 1
- 239000010953 base metal Substances 0.000 description 1
- BRPQOXSCLDDYGP-UHFFFAOYSA-N calcium oxide Chemical compound [O-2].[Ca+2] BRPQOXSCLDDYGP-UHFFFAOYSA-N 0.000 description 1
- ODINCKMPIJJUCX-UHFFFAOYSA-N calcium oxide Inorganic materials [Ca]=O ODINCKMPIJJUCX-UHFFFAOYSA-N 0.000 description 1
- 239000000292 calcium oxide Substances 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000011159 matrix material Substances 0.000 description 1
Landscapes
- Powder Metallurgy (AREA)
Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は、含浸型陰極用タングス
テン粉末焼結体の製造方法に関し、特に高電流密度用の
含浸型陰極用タングステン粉末焼結体の製造方法に関す
る。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a tungsten powder sintered body for an impregnated cathode, and more particularly to a method for producing a tungsten powder sintered body for an impregnated cathode for high current density.
【０００２】[0002]
【従来の技術】従来の含浸型陰極タングステン粉末焼結
体（以下、ポーラスＷ棒という）は、平均粒径が４〜５
μｍのタングステン粉末を１ｔｏｎ／平方ｃｍの圧力で
プレス成形した後、水素雰囲気中、又は真空雰囲気中に
おいて約２０００℃で加熱、焼結させ製作されている。2. Description of the Related Art A conventional impregnated type cathode tungsten powder sintered body (hereinafter referred to as a porous W rod) has an average particle size of 4-5.
It is manufactured by pressing tungsten powder of μm at a pressure of 1 ton / cm 2 and then heating and sintering at about 2000 ° C. in a hydrogen atmosphere or a vacuum atmosphere.
【０００３】このポーラスＷ棒を用いて製作される含浸
型陰極は、マトリックス状のタングステン焼結体の中に
酸化バリウム、酸化カルシウム、及び酸化アルミニウム
が含浸された構造であるため、その基体金属であるポー
ラス棒も空孔率が約２０％のマトリックス状にする必要
がある。上記方法によって製作されたポーラスＷ棒はタ
ングステン粒の大きさが４〜８μｍ、空孔径が３〜６μ
ｍのマトリックスを形成する。The impregnated cathode manufactured using this porous W rod has a structure in which barium oxide, calcium oxide, and aluminum oxide are impregnated in a matrix-shaped tungsten sintered body, so that the base metal is used. Certain porous rods also need to be matrixed with a porosity of about 20%. The porous W rod manufactured by the above method has a tungsten grain size of 4 to 8 μm and a pore diameter of 3 to 6 μm.
form a matrix of m.
【０００４】[0004]
【発明が解決しようとする課題】上述したように従来の
ポーラスＷ棒は、タングステン粉末の粒径が４〜８μ
ｍ、空孔径が３〜６μｍとなるため、次のような問題点
があった。すなわち、As described above, in the conventional porous W rod, the particle size of the tungsten powder is 4 to 8 μm.
Since m and the pore diameter are 3 to 6 μm, there are the following problems. That is,
【０００５】含浸型陰極は、空孔に含浸されたバリウ
ムの表面拡散により仕事関数を低下させ電子を取り出し
ている。このため、空孔からしみだしたバリウムが陰極
全体に均一に拡散すれば最も仕事関数の低い良好な含浸
型陰極が得られる。In the impregnated cathode, the work function is lowered by the surface diffusion of barium impregnated in the holes and electrons are taken out. Therefore, if barium exuding from the holes diffuses uniformly throughout the cathode, an excellent impregnated cathode with the lowest work function can be obtained.
【０００６】しかし、タングステン粉末の平均粒径が４
〜５μｍと大きいと、バリウムが陰極表面全体に拡散す
る前に蒸発してしまい、バリウムの拡散していないタン
グステン表面の領域が発生し、含浸型陰極表面の仕事関
数を増加させてしまう。又、タングステン粉末同士が２
次焼結し、タングステン粒が６〜８μｍになった場合
は、バリウムの拡散面積がさらに減少し、仕事関数の低
下が顕著となる。However, the average particle size of the tungsten powder is 4
If it is as large as ˜5 μm, barium is evaporated before it is diffused over the entire surface of the cathode, a region of the tungsten surface in which barium is not diffused is generated, and the work function of the impregnated cathode surface is increased. Also, if the tungsten powder is 2
In the case where the tungsten particles are 6 to 8 μm after the subsequent sintering, the diffusion area of barium is further reduced, and the work function is significantly reduced.
【０００７】このように空孔からのバリウムの拡散が含
浸型陰極表面上で不均一となると、含浸型陰極からの電
子放出分布が不均一となるため、進行波管などではヘリ
ックス電流の増加など異常電流が発生する。When the diffusion of barium from the holes becomes non-uniform on the surface of the impregnated cathode as described above, the electron emission distribution from the impregnated cathode becomes non-uniform, so that the helix current increases in a traveling wave tube or the like. Abnormal current occurs.
【０００８】従来の方法で上記問題点を解決するため
にタングステン粉末の粒径を１〜４μｍに小さくする
と、タングステン粒子が密に詰まるため、空孔率が１７
％以下になってしまい、上記同様仕事関数が増加し、含
浸型陰極として使用することができない。When the particle size of the tungsten powder is reduced to 1 to 4 μm in order to solve the above problems by the conventional method, the tungsten particles are closely packed and the porosity is 17
%, The work function increases as in the above case, and it cannot be used as an impregnated cathode.
【０００９】本発明の目的は、含浸型陰極の仕事関数を
低下させ、電子放出特性を向上させる含浸型陰極用タン
グステン粉末焼結体の製造方法を提供することにある。An object of the present invention is to provide a method for producing a tungsten powder sintered body for an impregnated cathode, which lowers the work function of the impregnated cathode and improves electron emission characteristics.
【００１０】[0010]
【課題を解決するための手段】前記目的を達成するた
め、本発明に係る含浸型陰極用タングステン粉末焼結体
の製造方法は、タングステン粉末を円柱形状にプレス加
工し、同時に焼結して含浸型陰極用タングステン粉末焼
結体を製造する方法であって、タングステン粉末の平均
粒径は、１〜４μｍであり、タングステン粉末のプレス
加工は、高温等方圧プレスにより行うものである。In order to achieve the above object, a method of manufacturing a tungsten powder sintered body for an impregnated type cathode according to the present invention comprises a step of pressing a tungsten powder into a cylindrical shape, and at the same time sintering and impregnation. A method for producing a tungsten powder sintered body for a mold cathode, wherein the average particle diameter of the tungsten powder is 1 to 4 μm, and the pressing of the tungsten powder is performed by a high temperature isotropic pressing.
【００１１】また、前記高温等方圧プレスのプレス温度
は、９００〜１２００℃であり、プレス圧は、１０００
〜１５００気圧である。The pressing temperature of the high temperature isotropic press is 900 to 1200 ° C., and the pressing pressure is 1000.
~ 1500 atm.
【００１２】また、水素雰囲気中又は真空雰囲気中にて
１６００℃以上で焼結体の再焼結を行うものである。The sintered body is re-sintered at 1600 ° C. or higher in a hydrogen atmosphere or a vacuum atmosphere.
【００１３】[0013]
【作用】本発明の含浸型陰極用タングステン粉末焼結体
は、ＨＩＰによりプレスと焼結とを同時に行い、その後
１６００℃以上で再焼結させることにより、空孔率を約
２０％に制御することが可能であり、従来のような空孔
率の低下を防止する。The porosity of the tungsten powder sintered body for impregnated cathodes of the present invention is controlled to about 20% by simultaneously pressing and sintering by HIP and then re-sintering at 1600 ° C. or higher. It is possible to prevent the decrease in porosity as in the conventional case.
【００１４】[0014]
【実施例】次に、本発明の実施例について図面を用いて
説明する。図１は、本発明の製造方法を実施するＨＩＰ
装置の縦断面図、図２は、本発明によるポーラスＷ棒の
断面図である。Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 shows a HIP for carrying out the manufacturing method of the present invention.
FIG. 2 is a vertical sectional view of the device, and FIG. 2 is a sectional view of a porous W rod according to the present invention.
【００１５】まず、平均粒径１〜４μｍのタングステン
粉末を約１〜３ｔｏｎ／平方ｃｍの水圧プレスにより１
次プレスし、所定の円柱形状に成形する。次に、図１に
示すように成形したタングステン粉末成形体１をガラス
管２に挿入し、酸化アルミニウム３中に埋め込む。次に
埋め込んだガラス管２を１×１０-6の真空度まで排気
し、気密封止する。First, a tungsten powder having an average particle size of 1 to 4 μm is pressed with a hydraulic press of about 1 ton ton / cm 2 to a pressure of 1.
Next, it is pressed to form a predetermined cylindrical shape. Next, the tungsten powder compact 1 molded as shown in FIG. 1 is inserted into the glass tube 2 and embedded in the aluminum oxide 3. Next, the embedded glass tube 2 is evacuated to a vacuum degree of 1 × 10 −6 and hermetically sealed.
【００１６】ガラス管２中に真空気密したタングステン
粉末成形体１と酸化アルミニウム３をプレス容器４中の
酸化アルミニウム５に埋め込む。これをＨＩＰの圧力室
６に配置し、周囲の加熱ヒータ７により約１０００℃に
加熱しながらアルゴンガス８により１５００気圧の圧力
を９０分間かけ、プレス加工と焼結とを同時に行う。A vacuum-tight tungsten powder compact 1 and aluminum oxide 3 are embedded in a glass tube 2 in an aluminum oxide 5 in a press container 4. This is placed in the pressure chamber 6 of the HIP, and the pressure of 1500 atm is applied for 90 minutes by the argon gas 8 while heating it to about 1000 ° C. by the heater 7 in the periphery, and the press working and the sintering are performed simultaneously.
【００１７】さらに空孔率を２０％にあわせるため、水
素雰囲気中で１６００℃、１０分の再焼結を行う。Further, in order to adjust the porosity to 20%, re-sintering is performed at 1600 ° C. for 10 minutes in a hydrogen atmosphere.
【００１８】このように製作されたポーラスＷの断面は
図２に示すように４〜８μｍに結晶成長したタングステ
ン２次結晶９の中に１〜３μｍの１次結晶１０により形
成された空孔１１があり、さらにタングステン２次結晶
により形成された３〜４μｍの空孔１２が空孔１１の周
囲に形成されている。As shown in FIG. 2, the cross section of the porous W produced in this manner has holes 11 formed by the primary crystal 10 having a thickness of 1 to 3 μm in the tungsten secondary crystal 9 having a crystal growth of 4 to 8 μm. In addition, the holes 12 of 3 to 4 μm formed by the secondary crystal of tungsten are formed around the holes 11.
【００１９】従来の方法によるポーラスＷの断面図を図
４に示す。このように４〜５μｍのタングステン粉末で
はタングステン粒径が大きいため、結晶全体で結晶成長
が起こりにくいため、２次結晶が均一に形成されない。
このために１次結晶粒界１９により形成された３〜４μ
ｍの空孔２０しか形成されない。A cross-sectional view of the porous W according to the conventional method is shown in FIG. As described above, since the tungsten powder having a particle size of 4 to 5 μm has a large tungsten grain size, crystal growth hardly occurs in the entire crystal, so that secondary crystals are not uniformly formed.
For this reason, 3 to 4 μ formed by the primary grain boundaries 19
Only m holes 20 are formed.
【００２０】図３は本発明の別の実施例に係るポーラス
Ｗ棒を示す縦断面図である。１〜３μｍのタングステン
粉末と０．１〜２μｍのイリジウム粉末を４：１の割合
で良く混合した後、前記実施例と同様にＨＩＰ、再結晶
を行いポーラスＷを作製すると、図３に示す通り、タン
グステン１３とイリジウム１４との１次結晶粒界１５に
０．５〜３μｍの空孔１６が形成され、さらに２次結晶
粒界１７に３〜４μｍの空孔１８が形成される。FIG. 3 is a vertical sectional view showing a porous W rod according to another embodiment of the present invention. After thoroughly mixing 1 to 3 μm of tungsten powder and 0.1 to 2 μm of iridium powder in a ratio of 4: 1, HIP and recrystallization are performed in the same manner as in the above-described example to produce a porous W, as shown in FIG. , 0.5 to 3 μm of pores 16 are formed in the primary crystal grain boundaries 15 of the tungsten 13 and the iridium 14, and further 3 to 4 μm of pores 18 are formed in the secondary crystal grain boundaries 17.
【００２１】以上説明したようにＨＩＰによりプレス加
工と焼結とを同時に行なうことにより、１次結晶粒界に
空孔を形成した後、再結晶により結晶成長を起こさせ、
２次結晶粒界による空孔を形成するため、含浸型陰極表
面全体に均一で、小さい空孔を形成することが可能とな
った。As described above, the press working and the sintering are simultaneously performed by HIP to form the pores in the primary crystal grain boundaries, and then the crystal growth is caused by the recrystallization,
Since the voids are formed by the secondary crystal grain boundaries, it becomes possible to form uniform and small voids on the entire surface of the impregnated type cathode.
【００２２】さらに本発明による含浸型陰極用タングス
テン粉末焼結体により含浸型陰極を製作した場合、含浸
工程が同一でも図５に示すように仕事関数が０．０２〜
０．０５ｅＶ小さくなるという結果を得た。Furthermore, when an impregnated cathode is manufactured from the tungsten powder sintered body for impregnated cathode according to the present invention, the work function is 0.02 to 0.02 as shown in FIG.
The result was 0.05 eV smaller.
【００２３】[0023]
【発明の効果】以上説明したように本発明は、１〜４μ
ｍのタングステン粉末を使用し、ＨＩＰ、再焼結するこ
とによって空孔率を２０％に制御し、小さい空孔を陰極
表面全体に均一に形成することによって、含浸型陰極の
仕事関数を図５のように０．０２〜０．０５ｅＶ低下さ
せ、電子放出特性を向上させることができるという効果
がある。As described above, the present invention is 1 to 4 μm.
The work function of the impregnated cathode is shown in FIG. 5 by controlling the porosity to 20% by HIP and re-sintering using tungsten powder of m, and forming small pores uniformly on the entire cathode surface. As described above, there is an effect that the electron emission characteristic can be improved by lowering 0.02 to 0.05 eV.
【図１】本発明の製造方法を実施するＨＩＰ装置を示す
縦断面図である。FIG. 1 is a vertical sectional view showing a HIP device for carrying out a manufacturing method of the present invention.
【図２】本発明によるポーラスＷ棒を示す断面図であ
る。FIG. 2 is a sectional view showing a porous W rod according to the present invention.
【図３】本発明の別の実施例に係るポーラスＷ棒を示す
断面図である。FIG. 3 is a sectional view showing a porous W rod according to another embodiment of the present invention.
【図４】従来の方法によるポーラスＷ棒を示す断面図で
ある。FIG. 4 is a sectional view showing a porous W rod according to a conventional method.
【図５】本発明と従来例との特性を示す図である。FIG. 5 is a diagram showing characteristics of the present invention and a conventional example.
１ タングステン粉末成形体 ２ ガラス管 ３，５ 酸化アルミニウム ４ プレス容器 ６ ＨＩＰ圧力室 ７ 加熱ヒータ ８ アルゴンガス ９ タングステン２次結晶 １０，１９ タングステン１次結晶 １１，１２，１６，１８，２０ 空孔 １３ タングステン １４ イリジウム １５ １次結晶粒界 １７ ２次結晶粒界 DESCRIPTION OF SYMBOLS 1 Tungsten powder compact 2 Glass tube 3,5 Aluminum oxide 4 Press container 6 HIP pressure chamber 7 Heater 8 Argon gas 9 Tungsten secondary crystal 10,19 Tungsten primary crystal 11, 12, 16, 18, 20 Vacancy 13 Tungsten 14 Iridium 15 Primary grain boundary 17 Secondary grain boundary
Claims (3)
工し、同時に焼結して含浸型陰極用タングステン粉末焼
結体を製造する方法であって、 タングステン粉末の平均粒径は、１〜４μｍであり、 タングステン粉末のプレス加工は、高温等方圧プレスに
より行うものであることを特徴とする含浸型陰極用タン
グステン粉末焼結体の製造方法。1. A method for manufacturing a tungsten powder sintered body for an impregnated cathode by pressing tungsten powder into a cylindrical shape and simultaneously sintering the tungsten powder, wherein the average particle diameter of the tungsten powder is 1 to 4 μm. A method for producing a tungsten powder sintered body for an impregnated cathode, characterized in that the pressing of the tungsten powder is performed by a high temperature isotropic pressing.
９００〜１２００℃であり、 プレス圧は、１０００〜１５００気圧であることを特徴
とする請求項１に記載の含浸型陰極用タングステン粉末
焼結体の製造方法。2. The press temperature of the high temperature isotropic press is:
It is 900-1200 degreeC, Pressing pressure is 1000-1500 atmospheres, The manufacturing method of the tungsten powder sintered compact for impregnation type cathodes of Claim 1 characterized by the above-mentioned.
００℃以上で焼結体の再焼結を行うことを特徴とする請
求項１に記載の含浸型陰極用タングステン粉末焼結体の
製造方法。3. 16 in a hydrogen atmosphere or a vacuum atmosphere
The method for producing a tungsten powder sintered body for an impregnated cathode according to claim 1, wherein the sintered body is re-sintered at a temperature of 00 ° C or higher.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP4190070A JP2910426B2 (en) | 1992-06-24 | 1992-06-24 | Manufacturing method of tungsten powder sintered body for impregnated cathode |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP4190070A JP2910426B2 (en) | 1992-06-24 | 1992-06-24 | Manufacturing method of tungsten powder sintered body for impregnated cathode |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH0612978A true JPH0612978A (en) | 1994-01-21 |
| JP2910426B2 JP2910426B2 (en) | 1999-06-23 |
Family
ID=16251862
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP4190070A Expired - Lifetime JP2910426B2 (en) | 1992-06-24 | 1992-06-24 | Manufacturing method of tungsten powder sintered body for impregnated cathode |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2910426B2 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2007194020A (en) * | 2006-01-18 | 2007-08-02 | Matsushita Electric Ind Co Ltd | Cathode material for flash discharge tube and flash discharge tube equipped with the cathode material |
-
1992
- 1992-06-24 JP JP4190070A patent/JP2910426B2/en not_active Expired - Lifetime
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2007194020A (en) * | 2006-01-18 | 2007-08-02 | Matsushita Electric Ind Co Ltd | Cathode material for flash discharge tube and flash discharge tube equipped with the cathode material |
Also Published As
| Publication number | Publication date |
|---|---|
| JP2910426B2 (en) | 1999-06-23 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| JPS58154131A (en) | Impregnation type cathode | |
| US3584253A (en) | Getter structure for electrical discharge and method of making the same | |
| JPH0558207B2 (en) | ||
| US4146497A (en) | Supported getter | |
| EP0409275A2 (en) | Method for fabricating an impregnated type cathode | |
| US4310603A (en) | Dispenser cathode | |
| EP0299126A1 (en) | Impregnated thermionic cathode | |
| EP0390269B1 (en) | Scandate cathode | |
| JPH0612978A (en) | Manufacture of tungsten powder sintered body for impregnation type cathode | |
| US5294399A (en) | Preparation of cathode structures for impregnated cathodes | |
| US2874077A (en) | Thermionic cathodes | |
| US3688150A (en) | Degassing arrangement for electron beam tube including an mk dispenser cathode | |
| CA1150763A (en) | Method of fabricating a dispenser cathode | |
| JP2710700B2 (en) | Method for producing impregnated cathode and cathode obtained by this method | |
| JP2001006521A (en) | Cathode body structure and color picture tube | |
| US3010826A (en) | Method of making dispenser type cathodes | |
| JPS59203343A (en) | Impregnated cathode | |
| US3166836A (en) | Manufacture of electron tube cathodes | |
| KR100259298B1 (en) | Impregnation-type cathode for crt | |
| JPH0630214B2 (en) | Impregnated cathode and manufacturing method thereof | |
| US4424044A (en) | Method of fabricating cathode electrodes | |
| JP3068160B2 (en) | Impregnated cathode and method for producing the same | |
| JPH0574337A (en) | Manufacture of impregnation-type cathode | |
| SU590085A1 (en) | Method of making tungsten-based porous thermal cathode | |
| KR920004551B1 (en) | Dispensor cathode |