US3769008A - Method for sintering workpieces of pressed powdered refractory metal or alloy and vacuum furnace for performing the same - Google Patents
Method for sintering workpieces of pressed powdered refractory metal or alloy and vacuum furnace for performing the same Download PDFInfo
- Publication number
- US3769008A US3769008A US00144719A US3769008DA US3769008A US 3769008 A US3769008 A US 3769008A US 00144719 A US00144719 A US 00144719A US 3769008D A US3769008D A US 3769008DA US 3769008 A US3769008 A US 3769008A
- Authority
- US
- United States
- Prior art keywords
- workpiece
- sintering
- heater
- workpieces
- vacuum furnace
- 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.)
- Expired - Lifetime
Links
- 238000005245 sintering Methods 0.000 title claims abstract description 24
- 238000000034 method Methods 0.000 title abstract description 23
- 239000003870 refractory metal Substances 0.000 title abstract description 11
- 229910045601 alloy Inorganic materials 0.000 title description 3
- 239000000956 alloy Substances 0.000 title description 3
- 238000010438 heat treatment Methods 0.000 claims abstract description 15
- 239000007789 gas Substances 0.000 abstract description 7
- 238000002844 melting Methods 0.000 abstract description 6
- 230000008018 melting Effects 0.000 abstract description 6
- 239000000463 material Substances 0.000 abstract description 5
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 description 3
- 229910052750 molybdenum Inorganic materials 0.000 description 3
- 239000011733 molybdenum Substances 0.000 description 3
- 230000015572 biosynthetic process Effects 0.000 description 2
- 238000010894 electron beam technology Methods 0.000 description 2
- 239000012212 insulator Substances 0.000 description 2
- QSHDDOUJBYECFT-UHFFFAOYSA-N mercury Chemical compound [Hg] QSHDDOUJBYECFT-UHFFFAOYSA-N 0.000 description 2
- 229910052753 mercury Inorganic materials 0.000 description 2
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 description 2
- 229910052721 tungsten Inorganic materials 0.000 description 2
- 239000010937 tungsten Substances 0.000 description 2
- 238000001816 cooling Methods 0.000 description 1
- 230000004907 flux Effects 0.000 description 1
- 230000014759 maintenance of location Effects 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 239000010955 niobium Substances 0.000 description 1
- GUCVJGMIXFAOAE-UHFFFAOYSA-N niobium atom Chemical compound [Nb] GUCVJGMIXFAOAE-UHFFFAOYSA-N 0.000 description 1
- 230000003287 optical effect Effects 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 238000005086 pumping Methods 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
Images
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
- B22F3/10—Sintering only
- B22F3/105—Sintering only by using electric current other than for infrared radiant energy, laser radiation or plasma ; by ultrasonic bonding
Definitions
- ABSTRACT A method for sintering workpieces of a pressed powdered refractory metal in vacuum. The method envisages simultaneous heating of the workpiece by electron bombardment over its entire surface. The workpiece to be treated is heated to a temperature which makes from 10 to 15 per cent of its material melting temperature and is at such temperature till gases cease to evolve therefrom.
- a vacuum furnace for performing the method has a heater made as a cathode surrounding the entire surface of the workpiece to be treated and placed at a uniform distance from the workpiece.
- the present invention relates to methods for sintering workpieces of pressed powdered refractory metal and to a vacuum furnace for effecting the process.
- a method for sintering workpieces of pressed powdered refractory metal or alloy comprises heating the workpiece by electron bombardment of its surface in a vacuum, the workpiece being moved in the focused electron beam.
- the sintering process is a vacuum furnace with a heater emitting an electron beam is a very slow one because the workpiece is heated gradually over small areas. The gases released from the heated area are partially absorbed by the previously heated areas. Additionally workpieces different in thickness and form cannot be heated evenly. Therefore only small flat and thin workpieces are treated using means for moving them in the focused beam of an electron gun.
- the workpiece areas to be treated are heated to a sintering temperature without retention it at intermediate temperatures; some gas has no time to escape from the workpiece before its shrinkage, which results in the formation of deep cracks on its surface and blowholes inside.
- the object of the present invention is to overcome the disadvantages of the above described method and apparatus known in the art.
- a specific object of the invention is to provide a method for sintering workpieces of pressed powdered refractory metal speeding up the sintering of the workpieces and improving their quality as well as ensuring the sintering of large articles of intricate shape.
- the method according to the invention allows speeding up the sintering process and sintering large intricate workpieces.
- a vacuum furnace has been developed with a heater emitting an electron flux; according to the invention the heater is made as a cathode surrounding the entire surface of the workpiece being treated.
- This furnace ensures a higher output and a higher quality of the articles obtained.
- the heater surrounding the workpiece to be treated is uniformly spaced from its surface.
- FIG. 2 is a sectional view of the furnace taken along.
- the vacuum furnace for performing themethod for sintering workpieces comprises a cylindrical water-cooled housing 1 with a cover 2 and a lifter 3. Inside the housing 1 on highvoltage insulators 4 there are mounted shields 5 made from sheet molybdenum.
- a heater 6' attached to electric lead-ins 7 is made as a cathode of tungsten or molybdenum sheets or wire which surrounds the entire surface of the workpiece 9. The heater 6 is coupled to heating and rectified high voltage-sources (not shown).
- a table 8 supports'the workpiece in a predetermined position and is driven vertically through a vacuumseal 10.
- the furnace housing 1 and the supporting table- 8 are grounded/For providing vacuum conditions in therange of 10" mm of mercury, the furnace is equipped with a high vacuum oil-free pump backed with a mechanical pump (not shown in the drawing).
- An optical pyrometer 11 and thermocouples are provided for measuring the workpiece temperature, as well as the temperature of separate elements of the furnace.
- the cover 2 is opened by the lifter 3.
- the pressed workpiece 9 is lowered onto the table 8.
- the heater 6' is placed around the workpiece at an equal distance from its surface.
- the cover 2 is lowered and the furnace is hermetically closed.
- the vacuum pumping equipment (not shown) is put into operation to provide the vacuum conditions required.
- the source of the heating voltage is switched on (not shown) and the cathodeheater 6 is heated to a temperature at which electron emmission commences from its surface.
- the source of rectified high voltage is switched on (not shown) and a negative potential is applied to the cathode.
- a fluxof electrons from the cathode is directed to the entire surface of the workpiece which becomes an anode.
- the surface of the workpiece is heated by the impingement of electrons upon it.
- the workpiece is heated up to the melting temperature, which makes from 10 to l5 per cent of its material melting temperature, and is kept at this temperature till the gases cease to evolve therefrom.
- the holding time depends on the amount of volatile components in the powder.
- Further heating of the workpiece right up to the sintering temperature is carried out at a rate of 50/min. After the isothermic holding at the sintering temperature, the heating of the cathode is discontinued and the high-voltage source. is disconnected. After the cooling of the workpiece down to room temperature, the furnace housing is unsealed and the workpiece removed from the heater.
- the method has been tested for sintering workpieces of powdered tungsten, molybdenum, columbium and of other refractory metals and alloys.
- the method according to the present invention allows obtaining practically porous-free sintered articles from the above-mentioned metals up to 250 mm in diameter and up to 400 mm in height.
- the articles contained insignificant amount of gaseous components uniformly distributed therein.
- a method for sintering workpieces of a pressed powdered refractory metal comprising providing a vacuum of about mm of mercury around said workpiece, heating the workpiece by simultaneous electron bombardment of its entire surface, from a heated cathode, up to a temperature which makes from 10 to per cent of its material melting temperature, holding the workpiece at such temperature until gases cease to evolve from the workpiece, and then heating the workpiece to a complete sintering temperature.
- a vacuum furnace for sintering workpieces comprising a table for supporting the workpiece to be treated; means movably supporting the table inside said furnace; a heater constituted as a cathode surrounding the entire surface of said workpiece, said heater comprising a plurality of parallel elements encircling the workpiece in facing relation at a substantially uniform spacing therefrom; and an electrical lead-in connected with said heater and with sources of high and heating voltages.
Abstract
A method for sintering workpieces of a pressed powdered refractory metal in vacuum. The method envisages simultaneous heating of the workpiece by electron bombardment over its entire surface. The workpiece to be treated is heated to a temperature which makes from 10 to 15 per cent of its material melting temperature and is at such temperature till gases cease to evolve therefrom. A vacuum furnace for performing the method has a heater made as a cathode surrounding the entire surface of the workpiece to be treated and placed at a uniform distance from the workpiece.
Description
United States Patent [1 1 Borok et a1.
[ METHOD FOR SINTERING WORKPIECES OF PRESSED POWDERED REFRACTORY METAL OR ALLOY AND VACUUM FURNACE FOR PERFORMING THE SAME [76] Inventors: Boris Alexandrovich Borok; Zhan losifovich Dzneladze; Leonid Nikolaevich Petrov; Evgeny Ivanovich Zaikin; Ivan Alexeevich Klynnsky; Boris Pavlovich Lobashov, all of Moscow, USSR.
[22] Filed: May 19, 1971 [21] Appl. No.: 144,719
[52] US. Cl 75/225, 75/200, 219/121 EB, 219/121 EM, 250/49.5 TE, 266/5 R, 266/24 [51] Int. Cl. B22f l/00, B23k 9/00, H011 37/26 [58] Field of Search 75/225, 200; 219/121 EBM, 121 EBA; 250/495 TE,
49.5 R; 266/24, 2 R 5 R [56] References Cited UNITED STATES PATENTS 2,227,177 12/1940 Berghaus et a1. 75/225 X 3,381,157 4/1968 Ferreira 313/348 3,183,086 5/1965 Kurtz et a1. 75/208 R X 2,994,801 8/1961 Hanks 219/121 EBA 1 Oct. 30, 1973 6/1960 Smith ..219/121EBM 2,942,098 2,809,905 10/1957 Davis et al 219/121 EBM FOREIGN PATENTS OR APPLICATIONS 37/1455 8/1962 Japan 75/225 OTHER PUBLICATIONS Brown, M. J., Western Electric Technical Digest, No. 15, July 1969, p. 25-26.
Primary Examiner-Carl D. Quarforth Assistant ExaminerR. E. Schafer Attorney-WatemRoditi, Schwartz & Nissen [57] ABSTRACT A method for sintering workpieces of a pressed powdered refractory metal in vacuum. The method envisages simultaneous heating of the workpiece by electron bombardment over its entire surface. The workpiece to be treated is heated to a temperature which makes from 10 to 15 per cent of its material melting temperature and is at such temperature till gases cease to evolve therefrom.
A vacuum furnace for performing the method has a heater made as a cathode surrounding the entire surface of the workpiece to be treated and placed at a uniform distance from the workpiece.
3 Claims, 2 Drawing Figures PAIENIEU um 30 I915 sum 1 BF 2 FIG. 2
METHOD FOR SINTERING WORKPIECES OF PRESSED POWDERED REFRACTORY METAL OR ALLOY AND VACUUM FURNACE FOR PERFORMING THE SAME The present invention relates to methods for sintering workpieces of pressed powdered refractory metal and to a vacuum furnace for effecting the process.
A method for sintering workpieces of pressed powdered refractory metal or alloy is known, which comprises heating the workpiece by electron bombardment of its surface in a vacuum, the workpiece being moved in the focused electron beam.
The sintering process is a vacuum furnace with a heater emitting an electron beam is a very slow one because the workpiece is heated gradually over small areas. The gases released from the heated area are partially absorbed by the previously heated areas. Additionally workpieces different in thickness and form cannot be heated evenly. Therefore only small flat and thin workpieces are treated using means for moving them in the focused beam of an electron gun. The workpiece areas to be treated are heated to a sintering temperature without retention it at intermediate temperatures; some gas has no time to escape from the workpiece before its shrinkage, which results in the formation of deep cracks on its surface and blowholes inside.
The object of the present invention is to overcome the disadvantages of the above described method and apparatus known in the art.
A specific object of the invention is to provide a method for sintering workpieces of pressed powdered refractory metal speeding up the sintering of the workpieces and improving their quality as well as ensuring the sintering of large articles of intricate shape.
These objects are achieved by providing a method for sintering workpieces of pressed powdered refractory metal, comprising heating the workpiece by electron bombardment of its surface in a vacuum, whereby, according to the invention, the entire surface of the workpiece is subjected to the electron bombardment simultaneously.
The method according to the invention allows speeding up the sintering process and sintering large intricate workpieces.
it is preferable to keep a workpiece heated to a temperature which makes from to 1-5 percent of its material melting temperature till the gas ceases to evolve from it.
This ensures a high quality of the articles, that is, by avoiding the formation of blowholes and deep cracks on their surfaces.
For performing this process, a vacuum furnace has been developed with a heater emitting an electron flux; according to the invention the heater is made as a cathode surrounding the entire surface of the workpiece being treated.
This furnace ensures a higher output and a higher quality of the articles obtained.
Preferably, the heater surrounding the workpiece to be treated is uniformly spaced from its surface.
This allows improvement of the quality of the intricate workpieces to be treated.
The invention will be more clearly understood by way of example with reference to the accompanying drawings, in which:
FIG. 2 is a sectional view of the furnace taken along.
the lines llll of FIG 1.
The vacuum furnace for performing themethod for sintering workpieces according to the present invention comprises a cylindrical water-cooled housing 1 with a cover 2 and a lifter 3. Inside the housing 1 on highvoltage insulators 4 there are mounted shields 5 made from sheet molybdenum. A heater 6' attached to electric lead-ins 7 is made as a cathode of tungsten or molybdenum sheets or wire which surrounds the entire surface of the workpiece 9. The heater 6 is coupled to heating and rectified high voltage-sources (not shown). A table 8 supports'the workpiece in a predetermined position and is driven vertically through a vacuumseal 10. The furnace housing 1 and the supporting table- 8 are grounded/For providing vacuum conditions in therange of 10" mm of mercury, the furnace is equipped with a high vacuum oil-free pump backed with a mechanical pump (not shown in the drawing). An optical pyrometer 11 and thermocouples (not shown) are provided for measuring the workpiece temperature, as well as the temperature of separate elements of the furnace.
In the operation of the apparatus described hereinbefore the cover 2 is opened by the lifter 3. The pressed workpiece 9 is lowered onto the table 8. The heater 6' is placed around the workpiece at an equal distance from its surface. Then the cover 2 is lowered and the furnace is hermetically closed. The vacuum pumping equipment (not shown) is put into operation to provide the vacuum conditions required. Further the source of the heating voltage is switched on (not shown) and the cathodeheater 6 is heated to a temperature at which electron emmission commences from its surface. Then the source of rectified high voltage is switched on (not shown) and a negative potential is applied to the cathode. Thus a fluxof electrons from the cathode is directed to the entire surface of the workpiece which becomes an anode. The surface of the workpiece is heated by the impingement of electrons upon it. By the electron bombardment, the workpiece is heated up to the melting temperature, which makes from 10 to l5 per cent of its material melting temperature, and is kept at this temperature till the gases cease to evolve therefrom. The holding time depends on the amount of volatile components in the powder. Further heating of the workpiece right up to the sintering temperature is carried out at a rate of 50/min. After the isothermic holding at the sintering temperature, the heating of the cathode is discontinued and the high-voltage source. is disconnected. After the cooling of the workpiece down to room temperature, the furnace housing is unsealed and the workpiece removed from the heater.
When high-voltage insulator 4 is used instead of seal 10, a high positive potential may be applied to the table 8, and the housing 1, shields 5 and the heater 6 are then grounded. The principle of the sintering method remains the same because in this case the cathode heater 6 will have a negative potential with respect to the anode the workpiece 9. The application of this mode of furnace electric supply allows separation of the sources of heating and rectified high voltages which simplifies the operation of the furnace.
The method has been tested for sintering workpieces of powdered tungsten, molybdenum, columbium and of other refractory metals and alloys.
The method according to the present invention allows obtaining practically porous-free sintered articles from the above-mentioned metals up to 250 mm in diameter and up to 400 mm in height. The articles contained insignificant amount of gaseous components uniformly distributed therein.
What we claim is l. A method for sintering workpieces of a pressed powdered refractory metal comprising providing a vacuum of about mm of mercury around said workpiece, heating the workpiece by simultaneous electron bombardment of its entire surface, from a heated cathode, up to a temperature which makes from 10 to per cent of its material melting temperature, holding the workpiece at such temperature until gases cease to evolve from the workpiece, and then heating the workpiece to a complete sintering temperature.
2. A vacuum furnace for sintering workpieces, comprising a table for supporting the workpiece to be treated; means movably supporting the table inside said furnace; a heater constituted as a cathode surrounding the entire surface of said workpiece, said heater comprising a plurality of parallel elements encircling the workpiece in facing relation at a substantially uniform spacing therefrom; and an electrical lead-in connected with said heater and with sources of high and heating voltages.
3. A vacuum furnace as claimed in claim 2 wherein said parallel heater elements extend substantially beyond the ends of the workpiece for heating the end faces of the workpiece.
Claims (2)
- 2. A vacuum furnace for sintering workpieces, comprising a table for supporting the workpiece to be treated; means movably supporting the table inside said furnace; a heater constituted as a cathode surrounding the entire surface of said workpiece, said heater comprising a plurality of parallel elements encircling the workpiece in facing relation at a substantially uniform spacing therefrom; and an electrical lead-in connected with said heater and with sources of high and heating voltages.
- 3. A vacuum furnace as claimed in claim 2 wherein said parallel heater elements extend substantially beyond the ends of the workpiece for heating the end faces of the workpiece.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US14471971A | 1971-05-19 | 1971-05-19 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| US3769008A true US3769008A (en) | 1973-10-30 |
Family
ID=22509826
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| US00144719A Expired - Lifetime US3769008A (en) | 1971-05-19 | 1971-05-19 | Method for sintering workpieces of pressed powdered refractory metal or alloy and vacuum furnace for performing the same |
Country Status (1)
| Country | Link |
|---|---|
| US (1) | US3769008A (en) |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3871630A (en) * | 1972-05-05 | 1975-03-18 | Leybold Heraeus Verwaltung | Apparatus for sintering pressed powder elements containing hydrocarbons |
| US3932760A (en) * | 1967-12-22 | 1976-01-13 | Inoue K | Powder activation in an inert atmosphere |
| US4401297A (en) * | 1977-03-30 | 1983-08-30 | Sumitomo Electric Industries, Ltd. | Sintering furnace for powder metallurgy |
| US5458754A (en) | 1991-04-22 | 1995-10-17 | Multi-Arc Scientific Coatings | Plasma enhancement apparatus and method for physical vapor deposition |
| US6080964A (en) * | 1998-04-16 | 2000-06-27 | Micafil Vakuumtechnik Ag | Process for predrying a coil block containing at least one winding and solid insulation |
| RU2516532C1 (en) * | 2012-11-07 | 2014-05-20 | Федеральное государственное бюджетное образовательное учреждение высшего профессионального образования "Томский государственный университет систем управления и радиоэлектроники" | Method to sinter products of dielectric ceramics |
Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2227177A (en) * | 1937-08-27 | 1940-12-31 | Berghaus | Method of sintering metal |
| US2809905A (en) * | 1955-12-20 | 1957-10-15 | Nat Res Dev | Melting and refining metals |
| US2942098A (en) * | 1958-08-04 | 1960-06-21 | Stauffer Chemical Co | Method for heating materials by electron bombardment in a vacuum |
| US2994801A (en) * | 1959-06-05 | 1961-08-01 | Stauffer Chemical Co | Electron beam generation |
| US3183086A (en) * | 1963-05-03 | 1965-05-11 | Kulite Tungsten Co | Method of making porous body with imperviously sealed surface |
| US3381157A (en) * | 1964-12-10 | 1968-04-30 | United Aircraft Corp | Annular hollow cathode discharge apparatus |
-
1971
- 1971-05-19 US US00144719A patent/US3769008A/en not_active Expired - Lifetime
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2227177A (en) * | 1937-08-27 | 1940-12-31 | Berghaus | Method of sintering metal |
| US2809905A (en) * | 1955-12-20 | 1957-10-15 | Nat Res Dev | Melting and refining metals |
| US2942098A (en) * | 1958-08-04 | 1960-06-21 | Stauffer Chemical Co | Method for heating materials by electron bombardment in a vacuum |
| US2994801A (en) * | 1959-06-05 | 1961-08-01 | Stauffer Chemical Co | Electron beam generation |
| US3183086A (en) * | 1963-05-03 | 1965-05-11 | Kulite Tungsten Co | Method of making porous body with imperviously sealed surface |
| US3381157A (en) * | 1964-12-10 | 1968-04-30 | United Aircraft Corp | Annular hollow cathode discharge apparatus |
Non-Patent Citations (1)
| Title |
|---|
| Brown, M. J., Western Electric Technical Digest, No. 15, July 1969, p. 25 26. * |
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3932760A (en) * | 1967-12-22 | 1976-01-13 | Inoue K | Powder activation in an inert atmosphere |
| US3871630A (en) * | 1972-05-05 | 1975-03-18 | Leybold Heraeus Verwaltung | Apparatus for sintering pressed powder elements containing hydrocarbons |
| US4401297A (en) * | 1977-03-30 | 1983-08-30 | Sumitomo Electric Industries, Ltd. | Sintering furnace for powder metallurgy |
| US5458754A (en) | 1991-04-22 | 1995-10-17 | Multi-Arc Scientific Coatings | Plasma enhancement apparatus and method for physical vapor deposition |
| US6139964A (en) | 1991-04-22 | 2000-10-31 | Multi-Arc Inc. | Plasma enhancement apparatus and method for physical vapor deposition |
| US6080964A (en) * | 1998-04-16 | 2000-06-27 | Micafil Vakuumtechnik Ag | Process for predrying a coil block containing at least one winding and solid insulation |
| RU2516532C1 (en) * | 2012-11-07 | 2014-05-20 | Федеральное государственное бюджетное образовательное учреждение высшего профессионального образования "Томский государственный университет систем управления и радиоэлектроники" | Method to sinter products of dielectric ceramics |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US2809905A (en) | Melting and refining metals | |
| US3219435A (en) | Method and apparatus for producing metal blocks by electron beams | |
| US3734480A (en) | Lamellar crucible for induction melting titanium | |
| US3769008A (en) | Method for sintering workpieces of pressed powdered refractory metal or alloy and vacuum furnace for performing the same | |
| US2227177A (en) | Method of sintering metal | |
| US3226223A (en) | Method and apparatus for melting metals by inductive heating and electron bombardment | |
| GB1039135A (en) | Improvements in or relating to heating by electron bombardment | |
| US2900281A (en) | Method of bonding metal borides to graphite | |
| US3779885A (en) | Apparatus and method for cathode sputtering on the two sides of a metallic support having large dimensions | |
| US848600A (en) | Production of homogeneous bodies from tantalum or other metals. | |
| US4225785A (en) | Process for the production of a sensitive plate for an exoelectron dosimeter | |
| US3037142A (en) | X-ray generator tubes | |
| US2968715A (en) | Fusion welding method and apparatus | |
| US2217205A (en) | Photoelectric tube | |
| Bischoff et al. | Writing implantation with a high current density focused ion beam | |
| US3791955A (en) | Preparation of chalcogenide glass sputtering targets | |
| US3595773A (en) | Process for depositing on surfaces | |
| US3338706A (en) | Metal processing method and resulting product | |
| US3140944A (en) | Method of sintering tungsten | |
| US2881104A (en) | Methods of producing refractory metal filaments of flattened zig-zag form | |
| US2452401A (en) | Method of regeneration of electron discharge devices | |
| Misiruk et al. | Non-self-sustained discharge with hollow anode for plasma-based surface treatment | |
| US3412196A (en) | Electron beam vacuum melting furnace | |
| US3156753A (en) | Melting furnace for metals | |
| US3227581A (en) | Process for rendering ceramics slightly conductive |