- Email: [email protected]
876. Investigation of mechanical strength of ceramic-to-metal seals at elevated temperatures
Classified abstracts
870-880
greater than that achieved in conventional models because the working surface area of the cryogenic pump is more extensive. V 0 Tokarev et al, USSR publd 17 July 1972.
Patent,
No 341,963,
appld
13 Ott
1970, 20
870. Vacuum electric furnace. (USSR)
An improvement to a standard electric vacuum furnace used for producing flexible superconductors (Nb,Sn) is described. The improvement lies in the fact that an additional working chamber is attached to the ordinary working chamber of the furnace; the Nb strip forming the base of the superconductor is coated with Sn and heat-treated in the main furnace at 800-9oo”C, then it passed into the second chamber, which is held at 95&105o”C, and the intermetallic compound Nb,Sn is thereby formed. The fact that the first stage of treatment is carried out at a lower temperature than the second has the effect that less tin is lost by evaporation; the relative proportions of the constituent elements are accordingly more easily preserved at the level most favourable for producing flexible superconducting strips. V K Enman et al, USSR Patent, 18 July 1972.
No 344,013, appld 8 Jan 1971, publd
22. GAUGES 22 871. Interlot density variation of a siloxane manometer fluid. (USA) The mean value of density for six samples of a siloxane manometer fluid is 1.06311 g/cm3 with an estimated standard deviation of 11 x 10m5 g/cm3 for the lot-to-lot variation in densitv of this fluid. From this r< it is concluded that for use of this material in manometry to the 0.01 ‘A level the density of the actual fluid used must be determined. P H Orcutt, J Vat Sci Technol, 10 (4), July-Aug 1973, 506. 22 872. Modulation of the desorbed ion current in Bayard-Alpert gauges. (USA)
The modulation characteristics of a Bayard-Alpert gauge have been investigated in the presence of a large residual current of desorbed ions, following exposure of the gauge to oxygen. Having observed an increase in the collector current on modulation, when the gas phase ion current was relatively small, modulation factors were measured for the desorbed ion current and were found to vary in magnitude up to 0.2. A sharp peak, which increased the amplitude of the mean residual current by approximately 30%, was also found in the modulation curve. Computed potential distributions and ion trajectories have shown that this peak can be atrtibuted to the focussing action of the electrostatic field on energetic ions desorbed from the modulator. Experimental verification of this hypothesis was obtained by selective cleaning of the grid and modulator using electron bombardment. L G Pittaway, J Val Sci Technol, 10 (4), July-Aug 1973, 507-512.
gas molecules of the system dary electrons A E Aisentson publd 15 May
in the system and hence to the pressure. The geometry ensures effective interception of the current of seconwhich actuate the pressure-recording instrument. et al. USSR Patent.
22 875. Tensometric vacuum transducer. (USSR) Construction of a special tensometric membrane transducer is described. The transducer can be used for recording of vacuum during hydraulic shocks in the pressure range of 0 to lo5 Pa. It can record processes with frequency up to 2400 Hz. V S Dikarevskiy and A E Tatura, fzmerit Tekh, No 6, June 1972, 91 (in Russian).
23. PLUMBING 876. Investigation of mechanical elevated temperatures. (USSR)
strength of ceramic-to-metal
compression
manometer.
(USSR) The bulb and capillary of this manometer are prepared in the form of a set of bushings made from vacuum-tight insulating material (ceramic) capable of withstanding heat, with metal discs and electrical contacts between them. All the elements are soldered hermetically. A compression vessel made in this way may be machined as a single unit and the inner surfaces of this vessel may be made extremely accurately, so that the relative volumes of the bulb and capillary, for example, are precisely known. The accuracy of pressure measurement therefore increases and so does the mechanical strength. R I Van’kovich et al, USSR Patent, publd 28 June 1972. 874. An electron ionization netic fields. (USSR)
No 340,922, appld 26 June 1970,
manometer
22 with crossed electric and mag-
In order to increase sensitivity and stability in the manometer here proposed, two cylindrical auxiliary cathodes are placed between the disc electrodes on either side of the cylindrical anode and coaxially with it, two disc screens at a positive potential lying between the auxiliary cathodes and the anode. All the electrodes lie in a magnetic field directed along the axis of the system. A heated cathode in front of the opening in the disc electrode serves as electron source, and the anode serves as a collector of the electron showers formed in the discharge gap. The anode current is proportional to the number of
seals ‘;;
Mechanical strength of ceramic-to-metal seals is investigated in the temperature range 20 to 1000°C in vacuum. Ceramics 22XC sealed to kovar or nickel with the aid of Mo-Mn metallizing layer was used. It is found that the metallizing layer forms the weak point of the seal. Yu N Kogan and V M Markovskiy, Zauodsk Lab, 38 (5), 1972, 596598 (in Russian). 877. Application of electron beam bombardment glass-to-metal seals. (Roumania)
for preparation
23 of
The method of preparation of bakeable glass-to-stainless steel seals is described. A kovar piece is inserted between steel tube and glass. The seal between glass and kovar is obtained with the aid of gas torch and the seal between kovar and stainless steel tube is performed with the aid of electron beam welding in vacuum. G Mariu and C Simonescu, Stud Si Cerc Fir, 24 (l), 1972, 137-141 (in Roumanian). 23 878. Vacuum valve. (USSR)
The vacuum valve here proposed differs from others in that it has one cylindrical cavity inside another, an easily-melting alloy being placed inside the outer cylinder, while the inner cylinder has an open end. The outer cylinder is connected to one of the exit tubes in the middle and is closed at both ends. The inner cylinder is connected to the other exit tube in the middle. When the valve is shut the inner cylinder has its open end downward. Then the cylindrical spaces connected to the exit tubes are separated by the alloy. In the open position the inner cylinder has its open end upwards, and the spaces connected to the exit tubes are also-connected to one another.. A S Fedorenko and A A Prvtkov. USSR Patent. No 342.245. , ,.*aDDid 5 Feb 1969, publd 17 July i972. ’ 23
22 873. Pressure vessel of an automatic
No 333.430. .__ aDold 24 AuaI 1970.,
1972:
: 24
879. Slide valve. (USSR)
A new type of slide valve distinguished by the fact that its electric heater is placed in a saddle equipped with an annular projection having a diameter less than the external diameter of the valve itself is described. The valve operates thus. To close the valve the cylindrical saddle is heated so that the diameter of the projection increases to a little more than the external diameter of the valve, then the plate is moved so as to rest against a support in the main body of the valve. The heater is then disconnected and the saddle cools, compressing the valve in such a way as to ensure vacuum tightness. To open the valve the saddle is heated and the operations proceed in reverse. Provision is made to vary the current through the heater so that the right amount of heat may be applied whatever the nature of the surroundings. V K Gagen-Tori and V Ya Moiseev, USSR Patent, No 351,022, appld 14 March 1970, publd 26 Sept 1972. 23 880. Gate system for passing objects into a vacuum system and withdrawing them. (USSR)
A revised gate system for passing objects into a vacuum system and withdrawing them without breaking the main vacuum is described. The principle of the gate system is that of a rotor with sockets provided for the objects which are to be passed into or out of thevaccum. After attaching the objects to these sockets the rotor is turned with 465
870-880
greater than that achieved in conventional models because the working surface area of the cryogenic pump is more extensive. V 0 Tokarev et al, USSR publd 17 July 1972.
Patent,
No 341,963,
appld
13 Ott
1970, 20
870. Vacuum electric furnace. (USSR)
An improvement to a standard electric vacuum furnace used for producing flexible superconductors (Nb,Sn) is described. The improvement lies in the fact that an additional working chamber is attached to the ordinary working chamber of the furnace; the Nb strip forming the base of the superconductor is coated with Sn and heat-treated in the main furnace at 800-9oo”C, then it passed into the second chamber, which is held at 95&105o”C, and the intermetallic compound Nb,Sn is thereby formed. The fact that the first stage of treatment is carried out at a lower temperature than the second has the effect that less tin is lost by evaporation; the relative proportions of the constituent elements are accordingly more easily preserved at the level most favourable for producing flexible superconducting strips. V K Enman et al, USSR Patent, 18 July 1972.
No 344,013, appld 8 Jan 1971, publd
22. GAUGES 22 871. Interlot density variation of a siloxane manometer fluid. (USA) The mean value of density for six samples of a siloxane manometer fluid is 1.06311 g/cm3 with an estimated standard deviation of 11 x 10m5 g/cm3 for the lot-to-lot variation in densitv of this fluid. From this r< it is concluded that for use of this material in manometry to the 0.01 ‘A level the density of the actual fluid used must be determined. P H Orcutt, J Vat Sci Technol, 10 (4), July-Aug 1973, 506. 22 872. Modulation of the desorbed ion current in Bayard-Alpert gauges. (USA)
The modulation characteristics of a Bayard-Alpert gauge have been investigated in the presence of a large residual current of desorbed ions, following exposure of the gauge to oxygen. Having observed an increase in the collector current on modulation, when the gas phase ion current was relatively small, modulation factors were measured for the desorbed ion current and were found to vary in magnitude up to 0.2. A sharp peak, which increased the amplitude of the mean residual current by approximately 30%, was also found in the modulation curve. Computed potential distributions and ion trajectories have shown that this peak can be atrtibuted to the focussing action of the electrostatic field on energetic ions desorbed from the modulator. Experimental verification of this hypothesis was obtained by selective cleaning of the grid and modulator using electron bombardment. L G Pittaway, J Val Sci Technol, 10 (4), July-Aug 1973, 507-512.
gas molecules of the system dary electrons A E Aisentson publd 15 May
in the system and hence to the pressure. The geometry ensures effective interception of the current of seconwhich actuate the pressure-recording instrument. et al. USSR Patent.
22 875. Tensometric vacuum transducer. (USSR) Construction of a special tensometric membrane transducer is described. The transducer can be used for recording of vacuum during hydraulic shocks in the pressure range of 0 to lo5 Pa. It can record processes with frequency up to 2400 Hz. V S Dikarevskiy and A E Tatura, fzmerit Tekh, No 6, June 1972, 91 (in Russian).
23. PLUMBING 876. Investigation of mechanical elevated temperatures. (USSR)
strength of ceramic-to-metal
compression
manometer.
(USSR) The bulb and capillary of this manometer are prepared in the form of a set of bushings made from vacuum-tight insulating material (ceramic) capable of withstanding heat, with metal discs and electrical contacts between them. All the elements are soldered hermetically. A compression vessel made in this way may be machined as a single unit and the inner surfaces of this vessel may be made extremely accurately, so that the relative volumes of the bulb and capillary, for example, are precisely known. The accuracy of pressure measurement therefore increases and so does the mechanical strength. R I Van’kovich et al, USSR Patent, publd 28 June 1972. 874. An electron ionization netic fields. (USSR)
No 340,922, appld 26 June 1970,
manometer
22 with crossed electric and mag-
In order to increase sensitivity and stability in the manometer here proposed, two cylindrical auxiliary cathodes are placed between the disc electrodes on either side of the cylindrical anode and coaxially with it, two disc screens at a positive potential lying between the auxiliary cathodes and the anode. All the electrodes lie in a magnetic field directed along the axis of the system. A heated cathode in front of the opening in the disc electrode serves as electron source, and the anode serves as a collector of the electron showers formed in the discharge gap. The anode current is proportional to the number of
seals ‘;;
Mechanical strength of ceramic-to-metal seals is investigated in the temperature range 20 to 1000°C in vacuum. Ceramics 22XC sealed to kovar or nickel with the aid of Mo-Mn metallizing layer was used. It is found that the metallizing layer forms the weak point of the seal. Yu N Kogan and V M Markovskiy, Zauodsk Lab, 38 (5), 1972, 596598 (in Russian). 877. Application of electron beam bombardment glass-to-metal seals. (Roumania)
for preparation
23 of
The method of preparation of bakeable glass-to-stainless steel seals is described. A kovar piece is inserted between steel tube and glass. The seal between glass and kovar is obtained with the aid of gas torch and the seal between kovar and stainless steel tube is performed with the aid of electron beam welding in vacuum. G Mariu and C Simonescu, Stud Si Cerc Fir, 24 (l), 1972, 137-141 (in Roumanian). 23 878. Vacuum valve. (USSR)
The vacuum valve here proposed differs from others in that it has one cylindrical cavity inside another, an easily-melting alloy being placed inside the outer cylinder, while the inner cylinder has an open end. The outer cylinder is connected to one of the exit tubes in the middle and is closed at both ends. The inner cylinder is connected to the other exit tube in the middle. When the valve is shut the inner cylinder has its open end downward. Then the cylindrical spaces connected to the exit tubes are separated by the alloy. In the open position the inner cylinder has its open end upwards, and the spaces connected to the exit tubes are also-connected to one another.. A S Fedorenko and A A Prvtkov. USSR Patent. No 342.245. , ,.*aDDid 5 Feb 1969, publd 17 July i972. ’ 23
22 873. Pressure vessel of an automatic
No 333.430. .__ aDold 24 AuaI 1970.,
1972:
: 24
879. Slide valve. (USSR)
A new type of slide valve distinguished by the fact that its electric heater is placed in a saddle equipped with an annular projection having a diameter less than the external diameter of the valve itself is described. The valve operates thus. To close the valve the cylindrical saddle is heated so that the diameter of the projection increases to a little more than the external diameter of the valve, then the plate is moved so as to rest against a support in the main body of the valve. The heater is then disconnected and the saddle cools, compressing the valve in such a way as to ensure vacuum tightness. To open the valve the saddle is heated and the operations proceed in reverse. Provision is made to vary the current through the heater so that the right amount of heat may be applied whatever the nature of the surroundings. V K Gagen-Tori and V Ya Moiseev, USSR Patent, No 351,022, appld 14 March 1970, publd 26 Sept 1972. 23 880. Gate system for passing objects into a vacuum system and withdrawing them. (USSR)
A revised gate system for passing objects into a vacuum system and withdrawing them without breaking the main vacuum is described. The principle of the gate system is that of a rotor with sockets provided for the objects which are to be passed into or out of thevaccum. After attaching the objects to these sockets the rotor is turned with 465