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The micro-determination of traces of gaseous elements in metals by the vacuum fusion method
VACUUM
Classified A b s t r a c t s III
--
Processing Techniques --
Vacuum
III
Abstract No. and References
Contd.
Apparatus for Attaching Filaments to Electrodes in Machines for Coating with Metal Vapours United Slates. This p a t e n t refers to the same technique as t h a t described in A b s t r a c t No. 170/III.
The particular design of the electrode tip suggested in A b s t r a c t No. 1 7 0 / I I I m a y prove to be expensive, in particular as it is n o r m a l l y intended for use on one occasion only. F o r this reason a more economical design of the electrode tip is proposed. Essential p a r t s of this can be used indefinitely. The modified design of the electrode tip consists of a cup-shaped a d a p t o r which can be slipped over the exposed lower end of the electrode a n d which is the p e r m a n e n t part. The a d a p t o r has a n u m b e r of concentrically arranged apertures in which wires are m o u n t e d , preferably of u n e q u a l length, the outer wires being shorter t h a n the inner wires. The cup and the wires should be of m o l y b d e n u m material. The ' hot-wire ' is introduced t h r o u g h the central a p e r t u r e of the a d a p t o r cup and anchored within b y suitable means. Two alternative designs of electrode tips based on the same a d a p t o r principle are also shown. Sommaire : Des d6tails sont donn6s d ' u n e am61ioration apport6e k l'appareil ddcrit dans le rdsum6 No. 170/III.
0
The Micro-Determination of Traces of Gaseous Elements in Metals by the Vacuum Fusion Method United Kingdom. The k n o w n m e t h o d s of gas d e t e r m i n a t i o n b y the v a c u u m - f u s i o n m e t h o d normally require samples of a size v a r y i n g from 5-25 g, from which 2-10 ml of gas are produced and analysed b y conventional methods. I n an effort to i m p r o v e and simplify this method, the a u t h o r s developed an a p p a r a t u s for v a c u u m fusion analysis on a m u c h smaller scale. Full details of the a p p a r a t u s and its operation are given. Five samples could be stored simultaneously and could be analysed successively in one run. The samples were placed into the crucible of the furnace b y magnetic means. A graphite crucible w a s used, s h a p e d in a m a n n e r which minimised uncontrolled e v a p o r a t i o n from the sample w i t h o u t seriously hindering gas evolution. The crucible was situated in a silica t u b e and was heated b y a high-frequency coil s u r r o u n d i n g the tube, M i n i m u m t e m p e r a t u r e of the furnace was 2,000°C. Gas analysis was carried o u t by m e a n s of the mass spectrometer, or, where the samples exceeded l0 cu. ram. b y the Blacet~Leighton method. The new m e t h o d was applied to the d e t e r m i n a t i o n of gas c o n t e n t in u r a n i u m samples and c o m p a r a t i v e m e a s u r e m e n t s were t a k e n b y m e a n s of a m a c r o - m e t h o d . F o r the results, see table reproduced below. The u r a n i u m samples employed in the micro-
171/III
Z. M. Shapiro & U.S. Atomic Energy Commission
U.S. Pat.
2,637,298
172/III
Comparison of the Proposed Method with Sloman's Method for Ura~i'am Analysis by Micro-Method Analysis by Sloman's Macro-Method Sampl l'Vo.
Oxygen % w/w
1
0.0078
0.0018
O.O
0.00°5
0000
11
Me o
.'Vitrogen Hydrogen % w/w ml. per 100 g
0008
0001
Sample] - -
Oxygen]Nitrogen] Hydroge,t % w/w % w/w ml. per 100 y.
A - - I - - O . O O 7 O I 0.0010 I 000 3 Mean I O00 l 000111
10
1.04
m e t h o d ranged in size from 120 to 190 rag. An a t t e m p t to determine the oxygen and nitrogen c o n t e n t in a zirconium sample was unsuccessful, m o s t likely for the reason t h a t the t e m p e r a t u r e of the furnace could n o t be raised high enough. Sommaire : Une m6thode de fusion sous vide, qui p e r m e t de dfceler des traces d'616ments gazeux dans de tr4s petits 6chantillons de m6tal, est d6crite.
J. N. Gregory D. Mapper & J. A. Woodward
Analyst
78, July 1953 414-427
0 Determination of Hydrogen in Wrought Aluminium Alloys See A b s t r a c t No. : 251/I
38 - -
DISTILLATION
173/III
- - 38
A Vacuum Anemometer
174/III
See A b s t r a c t No. : 170/II
Molecular Distillation United Kingdom. The typical features of molecular distillation are : Reduced pressure of the a t m o s p h e r e in
175/1II
the distillation c h a m b e r and a c o m p a r a t i v e l y s h o r t distance between the e v a p o r a t i n g and the condensing surface. If the latter is k e p t at 2 cm. and the pressure in the c h a m b e r at a b o u t 3 × 10 _3 ram. H g the distance between the 2 surfaces will be a b o u t equal to the m e a n free p a t h of the gas molecules and v a p o u r s rising from the e v a p o r a t i o n surface will reach the condensing surface w i t h o u t colliding with molecules of the residual gas. I n an a r r a n g e m e n t like this the rate of distillation is faster and the t e m p e r a t u r e at which distillation can be carried is lower t h a n in the case of the conventional distillation procedure. The condenser surface is n o r m a l l y held at 20°C and this limits the t y p e of materials which can be processed in this manner, as too volatile a material m a y re-evaporate from the condenser. On the o t h e r hand, substances of too high a molecular weight
October, 1953
Vacuum Vol. H I No. 4
471
Classified A b s t r a c t s III
--
Processing Techniques --
Vacuum
III
Abstract No. and References
Contd.
Apparatus for Attaching Filaments to Electrodes in Machines for Coating with Metal Vapours United Slates. This p a t e n t refers to the same technique as t h a t described in A b s t r a c t No. 170/III.
The particular design of the electrode tip suggested in A b s t r a c t No. 1 7 0 / I I I m a y prove to be expensive, in particular as it is n o r m a l l y intended for use on one occasion only. F o r this reason a more economical design of the electrode tip is proposed. Essential p a r t s of this can be used indefinitely. The modified design of the electrode tip consists of a cup-shaped a d a p t o r which can be slipped over the exposed lower end of the electrode a n d which is the p e r m a n e n t part. The a d a p t o r has a n u m b e r of concentrically arranged apertures in which wires are m o u n t e d , preferably of u n e q u a l length, the outer wires being shorter t h a n the inner wires. The cup and the wires should be of m o l y b d e n u m material. The ' hot-wire ' is introduced t h r o u g h the central a p e r t u r e of the a d a p t o r cup and anchored within b y suitable means. Two alternative designs of electrode tips based on the same a d a p t o r principle are also shown. Sommaire : Des d6tails sont donn6s d ' u n e am61ioration apport6e k l'appareil ddcrit dans le rdsum6 No. 170/III.
0
The Micro-Determination of Traces of Gaseous Elements in Metals by the Vacuum Fusion Method United Kingdom. The k n o w n m e t h o d s of gas d e t e r m i n a t i o n b y the v a c u u m - f u s i o n m e t h o d normally require samples of a size v a r y i n g from 5-25 g, from which 2-10 ml of gas are produced and analysed b y conventional methods. I n an effort to i m p r o v e and simplify this method, the a u t h o r s developed an a p p a r a t u s for v a c u u m fusion analysis on a m u c h smaller scale. Full details of the a p p a r a t u s and its operation are given. Five samples could be stored simultaneously and could be analysed successively in one run. The samples were placed into the crucible of the furnace b y magnetic means. A graphite crucible w a s used, s h a p e d in a m a n n e r which minimised uncontrolled e v a p o r a t i o n from the sample w i t h o u t seriously hindering gas evolution. The crucible was situated in a silica t u b e and was heated b y a high-frequency coil s u r r o u n d i n g the tube, M i n i m u m t e m p e r a t u r e of the furnace was 2,000°C. Gas analysis was carried o u t by m e a n s of the mass spectrometer, or, where the samples exceeded l0 cu. ram. b y the Blacet~Leighton method. The new m e t h o d was applied to the d e t e r m i n a t i o n of gas c o n t e n t in u r a n i u m samples and c o m p a r a t i v e m e a s u r e m e n t s were t a k e n b y m e a n s of a m a c r o - m e t h o d . F o r the results, see table reproduced below. The u r a n i u m samples employed in the micro-
171/III
Z. M. Shapiro & U.S. Atomic Energy Commission
U.S. Pat.
2,637,298
172/III
Comparison of the Proposed Method with Sloman's Method for Ura~i'am Analysis by Micro-Method Analysis by Sloman's Macro-Method Sampl l'Vo.
Oxygen % w/w
1
0.0078
0.0018
O.O
0.00°5
0000
11
Me o
.'Vitrogen Hydrogen % w/w ml. per 100 g
0008
0001
Sample] - -
Oxygen]Nitrogen] Hydroge,t % w/w % w/w ml. per 100 y.
A - - I - - O . O O 7 O I 0.0010 I 000 3 Mean I O00 l 000111
10
1.04
m e t h o d ranged in size from 120 to 190 rag. An a t t e m p t to determine the oxygen and nitrogen c o n t e n t in a zirconium sample was unsuccessful, m o s t likely for the reason t h a t the t e m p e r a t u r e of the furnace could n o t be raised high enough. Sommaire : Une m6thode de fusion sous vide, qui p e r m e t de dfceler des traces d'616ments gazeux dans de tr4s petits 6chantillons de m6tal, est d6crite.
J. N. Gregory D. Mapper & J. A. Woodward
Analyst
78, July 1953 414-427
0 Determination of Hydrogen in Wrought Aluminium Alloys See A b s t r a c t No. : 251/I
38 - -
DISTILLATION
173/III
- - 38
A Vacuum Anemometer
174/III
See A b s t r a c t No. : 170/II
Molecular Distillation United Kingdom. The typical features of molecular distillation are : Reduced pressure of the a t m o s p h e r e in
175/1II
the distillation c h a m b e r and a c o m p a r a t i v e l y s h o r t distance between the e v a p o r a t i n g and the condensing surface. If the latter is k e p t at 2 cm. and the pressure in the c h a m b e r at a b o u t 3 × 10 _3 ram. H g the distance between the 2 surfaces will be a b o u t equal to the m e a n free p a t h of the gas molecules and v a p o u r s rising from the e v a p o r a t i o n surface will reach the condensing surface w i t h o u t colliding with molecules of the residual gas. I n an a r r a n g e m e n t like this the rate of distillation is faster and the t e m p e r a t u r e at which distillation can be carried is lower t h a n in the case of the conventional distillation procedure. The condenser surface is n o r m a l l y held at 20°C and this limits the t y p e of materials which can be processed in this manner, as too volatile a material m a y re-evaporate from the condenser. On the o t h e r hand, substances of too high a molecular weight
October, 1953
Vacuum Vol. H I No. 4
471