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The activities of evaporated metal films in gas chemisorption
VACUUM Classified A b s t r a c t s
I --
General
Science and Engineering
--
Abstract No.
I
and References
Contd.
Group
Metals
Tungsten, A
O
Tantalum, Molybdenum, Titanium, Zi r coni um, Iron, Calcium, Barium.
B-
Nickel, Palladium, Rhodium, Platinum.
C
Copper, Aluminium.
D
Potassium.
E
Zinc, Cadmium, Indium, Tin, Lead, Silver.
F
Gold.
Gases
Nitrogen
Hydrogen
Carbon Monoxide
Ethylene
Acetylene
Oxygen
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
--
---
+
+
+
+
The metals are divided into six groups, A - F , in order of decreasing activity. The experiments prove t h a t the affinities of the gases to the metal surfaces investigated can be graded as follows : Oxygen>Acetylene>Ethylene>Carbon Monoxide>Hydrogen>Nitrogen A metal which chemisorbs one gas, will chemisorb all gases higher in the scale and vice versa if it does not chemisorb a particular gas, it will n o t chemisorb gases lower in the scale. The one exception is gold. The highest activities are shown, w i t h a few exceptions, b y the transition metals or metals h a v i n g the characteristic p a r t l y filled d - b a n d of the transition metals, represented b y groups A and ]3. T h u s chemisorption of all gasestudied a p p e a r s to require d - b a n d vacancies. B u t this does not a p p l y to oxygen. Oxygen chemisorption occurs on b o t h t r a n s i t i o n and n o n - t r a n s i t i o n metals. I n this case, chemisorption seems to take place w i t h the f o r m a t i o n of 02- ions, w h e r e b y the electrons are supplied from the s - or p b a n d of the metal, r a t h e r t h a n the d - b a n d . However, the b e h a v i o u r of gold c a n n o t be explained satisfactorily b y this theory. Sommaire: Des exp6riences o n t permis d'~tudier le mdcanisme de chimisorption sur environ soixante-dix m 6 t a u x diffdrents, exposes, sous forme de films evapords, ~ diffdrents gaz.
O
Sorption Properties of Thin Nickel Films Germany. An experimental and theoretical s t u d y of the sorption of oxygen and h y d r o g e n b y evaporated films of nickel. Details of the a p p a r a t u s and m e t h o d s are given. The sorption of oxygen can be considered as two processes, (a) the surface of the m e t a l film is first covered m o m e n t a r i l y b y a m o n a t o m i c layer of oxygen; (b) the oxygen a t o m s are t h e n forced into the interior of the fihn. (a) Is independent of the gas pressure in the sorption a p p a r a t u s . H y d r o g e n is n o t so strongly absorbed b y nickel b u t nickel which has previously been exposed to o x y g e n behaves differently t o w a r d s hydrogen, the sorption now being v e r y m u c h greater. Previous exposure of nickel films to h y d r o g e n does n o t influence the s u b s e q u e n t sorption of oxygen. (Science Abstracts) Sommaire : Les propridt6s de sorption de films fins de nickel ont 6t~ 5tudi6es vis A vis de l'oxyg~ne et de l'hydrog~ne.
The Solubility of Gases in Lubricating Oils and Fuels United Kingdom.. Oil or fuel employed in aircraft show excessive gas and v a p o u r evolution w h e n the plane reaches a, certain height. The actual altitude at which this p h e n o m e n o n occurs m a y v a r y w i t h the relevant properties of the material, i,e. with its v a p o u r pressure and the solubility coefficmnt of air in the material. So far as (low viscosity) aviation fuels arc concerned an accurate m e t h o d for the d e t e r m i n a t i o n of the solubility of gases in the m a t e r i a l is already in existence (see R.A.E. F a r n b o r o u g h , R e p o r t No. Chem. 464, 1950) b u t little is k n o w n on the properties and performance of (high viscosity) p e t r o l e u m oils in this respect. I n the p r e s e n t p a p e r a m e t h o d is described which facilitates gas solubility m e a s u r e m e n t s on p e t r o l e u m oils. This group of materials h a s a negligible v a p o u r pressure. I n the new m e t h o d the oil sample is fed into an evacuated vessel in order to liberate and r e m o v e all dissolved air. This process consists of three steps : D e g a s s i n g - - i n t e r m e d i a r y
January, 1954
Vacuum Vol. I V No. I
Article by B. M. W. Trapnell Proc. Roy. Soc. A, 2~8 23.7.1953 566-577 45/I
Article by W. Scheuble Z. Phys. x35, No. 2, 1953 125-140 46/I
93
I --
General
Science and Engineering
--
Abstract No.
I
and References
Contd.
Group
Metals
Tungsten, A
O
Tantalum, Molybdenum, Titanium, Zi r coni um, Iron, Calcium, Barium.
B-
Nickel, Palladium, Rhodium, Platinum.
C
Copper, Aluminium.
D
Potassium.
E
Zinc, Cadmium, Indium, Tin, Lead, Silver.
F
Gold.
Gases
Nitrogen
Hydrogen
Carbon Monoxide
Ethylene
Acetylene
Oxygen
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
--
---
+
+
+
+
The metals are divided into six groups, A - F , in order of decreasing activity. The experiments prove t h a t the affinities of the gases to the metal surfaces investigated can be graded as follows : Oxygen>Acetylene>Ethylene>Carbon Monoxide>Hydrogen>Nitrogen A metal which chemisorbs one gas, will chemisorb all gases higher in the scale and vice versa if it does not chemisorb a particular gas, it will n o t chemisorb gases lower in the scale. The one exception is gold. The highest activities are shown, w i t h a few exceptions, b y the transition metals or metals h a v i n g the characteristic p a r t l y filled d - b a n d of the transition metals, represented b y groups A and ]3. T h u s chemisorption of all gasestudied a p p e a r s to require d - b a n d vacancies. B u t this does not a p p l y to oxygen. Oxygen chemisorption occurs on b o t h t r a n s i t i o n and n o n - t r a n s i t i o n metals. I n this case, chemisorption seems to take place w i t h the f o r m a t i o n of 02- ions, w h e r e b y the electrons are supplied from the s - or p b a n d of the metal, r a t h e r t h a n the d - b a n d . However, the b e h a v i o u r of gold c a n n o t be explained satisfactorily b y this theory. Sommaire: Des exp6riences o n t permis d'~tudier le mdcanisme de chimisorption sur environ soixante-dix m 6 t a u x diffdrents, exposes, sous forme de films evapords, ~ diffdrents gaz.
O
Sorption Properties of Thin Nickel Films Germany. An experimental and theoretical s t u d y of the sorption of oxygen and h y d r o g e n b y evaporated films of nickel. Details of the a p p a r a t u s and m e t h o d s are given. The sorption of oxygen can be considered as two processes, (a) the surface of the m e t a l film is first covered m o m e n t a r i l y b y a m o n a t o m i c layer of oxygen; (b) the oxygen a t o m s are t h e n forced into the interior of the fihn. (a) Is independent of the gas pressure in the sorption a p p a r a t u s . H y d r o g e n is n o t so strongly absorbed b y nickel b u t nickel which has previously been exposed to o x y g e n behaves differently t o w a r d s hydrogen, the sorption now being v e r y m u c h greater. Previous exposure of nickel films to h y d r o g e n does n o t influence the s u b s e q u e n t sorption of oxygen. (Science Abstracts) Sommaire : Les propridt6s de sorption de films fins de nickel ont 6t~ 5tudi6es vis A vis de l'oxyg~ne et de l'hydrog~ne.
The Solubility of Gases in Lubricating Oils and Fuels United Kingdom.. Oil or fuel employed in aircraft show excessive gas and v a p o u r evolution w h e n the plane reaches a, certain height. The actual altitude at which this p h e n o m e n o n occurs m a y v a r y w i t h the relevant properties of the material, i,e. with its v a p o u r pressure and the solubility coefficmnt of air in the material. So far as (low viscosity) aviation fuels arc concerned an accurate m e t h o d for the d e t e r m i n a t i o n of the solubility of gases in the m a t e r i a l is already in existence (see R.A.E. F a r n b o r o u g h , R e p o r t No. Chem. 464, 1950) b u t little is k n o w n on the properties and performance of (high viscosity) p e t r o l e u m oils in this respect. I n the p r e s e n t p a p e r a m e t h o d is described which facilitates gas solubility m e a s u r e m e n t s on p e t r o l e u m oils. This group of materials h a s a negligible v a p o u r pressure. I n the new m e t h o d the oil sample is fed into an evacuated vessel in order to liberate and r e m o v e all dissolved air. This process consists of three steps : D e g a s s i n g - - i n t e r m e d i a r y
January, 1954
Vacuum Vol. I V No. I
Article by B. M. W. Trapnell Proc. Roy. Soc. A, 2~8 23.7.1953 566-577 45/I
Article by W. Scheuble Z. Phys. x35, No. 2, 1953 125-140 46/I
93