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728. Vacuum gas analyser
334
Classified Abstracts 725---731
apparatus consists of a cylindrical container with a capacity ~ 1 5 0 ml. to which a burette with graduations of 0.01 ml. is soldered at the top. The burette has at its end a three-way cock with two capillaries ; from below, a cylinder with Hg is connected through a rubber hose. The specimen 12 mm diameter and 40050 mm in length is pushed into the container through the opening at the bottom which can be stopped with a rubber plug. Then Hg from the cylinder is fed into the container and the burette, and some kind of gas analyser is connected to the capillary. The liberated volume of gas is measured in the burette, and the composition of the gas is determined in the gas analyser. Results on the determination of H2 in some carbon and alloy steels are given. It is established that the liberated gas usually contains 98 per cent H2 and 2 per cent air which becomes apparently adsorbed by the surface of the specimen. The method gives the same results as the method of vacuum extraction (in Czech). J. Vficlavinek, Hutn. Listy, 16 (4), 1961,[280-281.
in rate of evolution of gases to be determined and enabled them to be analysed on a mass spectrometer of the MS-2 type. Calculation formulae were obtained, enabling the rate of gas evolution to be determined, the working vacuum to be calculated and the possibilities of vacuum equipment to be estimated. It is evident that the factor limiting the rate of gas evolution in a vacuum are melt is the gap between the electrode and the walls of the crystallizer, the inadequate value of which may lead to a zero effect of the additional vacuum equipment from the apparatus on the furnace. It was shown on a crucible 100mm in diameter that when I = 1200 A, the main role in the refining of the metal is played by the floating up of inclusions (reduction of C oxides is not observed), that when I is increased to 1400 A, the character of the purification is not changed, but the processes of reduction of the inclusions which have floated up in the surface layer of the bath take place in the region of the anode, and that when I is increased to 2500°3000 A, reduction of the oxides takes place in the volume of liquid metal (in Russian).
37
L. N. Belyanchikov, R. N. Grigorash and A. V. Panov, Izv. Vyssh. Ucheb. Zaved. Chern. Metallurg. (9), 1961, 79-86.
725. Stanoveni obsahu plyn~ v prfi~kov~ch materifileeh metodu vakuov6 extrakee. (Determination of the gas content of powdered materials by the vacuum extraction method). Czechoslovakia. To determine gases in powdered materials which do not contain large amounts of gas, it is possible to use a pure Ni capsule. To analyse samples which contain much gas (e.g. oxides, nitrides), graphite capsules are better after a preliminary ignition at 2000 °. The construction of the capsule is described. A weighed amount of sample is taken, so calculated that the volume of the gas evolved amounts to 0.5-2 ml. (0.002 g of sample in the case of oxides or nitrides). The sample is mixed in the capsule with ~0.05 g of graphite powder, previously ignited at 2000 °, and placed in the vacuum extraction apparatus together with a piece of Cu or an alloy, which takes the place of an Fee bath. The method of extracting the gas (~1900 °) in the apparatus and the gas analysis, is the same for all solid materials. But in determining O3 in powdered materials, COs is determined with CO, so that its volume contribution cannot be neglected in this case. The method was checked on pure oxide powders and was used for the analysis of surface films on metals, on powdered ferrosilicon and for the determination of O3 in oxide membranes. The method is also applicable to the analysis of oxide and nitride inclusions (in Czech). J. V~clavinek, Hutn. Listy, 16 (7), 1961, 509-512. 37 726. Removal of oxygen in the process of arc vacuum smelting of special steels. U.S.S.R. To explain the mechanism of the purification of a metal from O3 during vacuum arc smelting, experiments on the vacuum arc smelting of low-carbon Fe, deoxidized and nondeoxidized, were carried out. It was shown that the removal of 02 in the form of CO took place only in the smelting of non-deoxidized metal. In the smelting of deoxidized Fe, and consequently of alloy steels, purification from 03 takes place mainly on account of the floating up of non-metallic inclusions and their flotation by bubbles of gas to the surface of the metal bath (in Russian). G. N. Okorokov, A. Yu. Polyakov and A. M. Samarin, Izv. Akad. Nauk SSSR, Otd. Tekh. Nauk, Metallarg. i Toplivo, (3), 1961, 3-9. 37 727. Kinetics of gas evolution in vacuum arc smelting. U.S.S.R. Gas evolution was studied on experimental melts of steels of types St.3, ShKh15, 79NMA, Kh20NS0 and heat resistant alloys based on Ni, in a laboratory vacuum arc furnace with wall crystallizers of 3, 7, 20 and 50 kg capacity. The gases evolved during the melt were collected in a container placed behind a booster pump, and this enabled the change
37 728. Vacuum gas analyser. Manufacturer's announcement, of the Wild-Barfield N.R.C. Model 912. Anon., J. Sci. Instrum., 38 (ll), Nov. 1961, 454 (see also correction, ibid., Dec. 1961, p. 519). 37 729. Az ac61 v~kuumban val6 6nt6senek csepeli tapasztalatai. (Experience of vacuum pouring of steel at the Csepel steelmelting works.) Hungary. Vacuum pouring from ladle to ladle was performed with the aim of decarburizing transformer and acid-resistant steel. The increased corrosion resistance due to decarburization is not sufficient to abandon the use of Ti additions to acidresistant steels. A study was made of the effect of vacuum on ingot structure, hardness and technological properties of steel. It was found that production of large castings in a vacuum is not desirable because of the large segregation of S, P and alloying elements (Cr, Mn), as a result of which a~ decreases with increasing oo. Vacuum treatment was found to have no effect on the quality of tubular components. Strip from vacuumtreated steel had higher ~b and 8. Vacuum treatment did not affect the hardenability of steel or the amount of non-metallic inclusions (in Hungarian). L. Sz6ke, Kohdsz. Lapok, 94 (4), 1961, 151-156. 37 730. Topography of oxidized graphite crystals. Great Britain. F r o m a recent study of gas-solid reactions, it appears that chemical reactivity depends markedly on the nature and density of crystal imperfections. In the case of graphite, both optical and electron microscopy have shown that oxidation often commences at surface atoms and proceeds in a direction perpendicular to the basal plane, forming well defined hexagonal pits. The authors have investigated this pit formation further and conclude that attack by oxygen is favoured by a lattice defect known as screw dislocation in the graphite crystal. Pronounced differences in the mode of graphite attack by oxygen and by carbon dioxide were noted. Pretreatment by hydrogen also affected the mode of subsequent oxidation. These factors are being investigated further, w.J.s. E. E. G. Hughes and J. M. Thomas, Nature, Lend., 193 (4818), 3 March 1962, 838-840. 37 731. The behaviour of components of complex alloys during fusion in vacuum induction furnaces. U.S.S.R. The behaviour of the components of Ni-based alloys containing up to 10 per cent Cr was investigated. It was
Classified Abstracts 725---731
apparatus consists of a cylindrical container with a capacity ~ 1 5 0 ml. to which a burette with graduations of 0.01 ml. is soldered at the top. The burette has at its end a three-way cock with two capillaries ; from below, a cylinder with Hg is connected through a rubber hose. The specimen 12 mm diameter and 40050 mm in length is pushed into the container through the opening at the bottom which can be stopped with a rubber plug. Then Hg from the cylinder is fed into the container and the burette, and some kind of gas analyser is connected to the capillary. The liberated volume of gas is measured in the burette, and the composition of the gas is determined in the gas analyser. Results on the determination of H2 in some carbon and alloy steels are given. It is established that the liberated gas usually contains 98 per cent H2 and 2 per cent air which becomes apparently adsorbed by the surface of the specimen. The method gives the same results as the method of vacuum extraction (in Czech). J. Vficlavinek, Hutn. Listy, 16 (4), 1961,[280-281.
in rate of evolution of gases to be determined and enabled them to be analysed on a mass spectrometer of the MS-2 type. Calculation formulae were obtained, enabling the rate of gas evolution to be determined, the working vacuum to be calculated and the possibilities of vacuum equipment to be estimated. It is evident that the factor limiting the rate of gas evolution in a vacuum are melt is the gap between the electrode and the walls of the crystallizer, the inadequate value of which may lead to a zero effect of the additional vacuum equipment from the apparatus on the furnace. It was shown on a crucible 100mm in diameter that when I = 1200 A, the main role in the refining of the metal is played by the floating up of inclusions (reduction of C oxides is not observed), that when I is increased to 1400 A, the character of the purification is not changed, but the processes of reduction of the inclusions which have floated up in the surface layer of the bath take place in the region of the anode, and that when I is increased to 2500°3000 A, reduction of the oxides takes place in the volume of liquid metal (in Russian).
37
L. N. Belyanchikov, R. N. Grigorash and A. V. Panov, Izv. Vyssh. Ucheb. Zaved. Chern. Metallurg. (9), 1961, 79-86.
725. Stanoveni obsahu plyn~ v prfi~kov~ch materifileeh metodu vakuov6 extrakee. (Determination of the gas content of powdered materials by the vacuum extraction method). Czechoslovakia. To determine gases in powdered materials which do not contain large amounts of gas, it is possible to use a pure Ni capsule. To analyse samples which contain much gas (e.g. oxides, nitrides), graphite capsules are better after a preliminary ignition at 2000 °. The construction of the capsule is described. A weighed amount of sample is taken, so calculated that the volume of the gas evolved amounts to 0.5-2 ml. (0.002 g of sample in the case of oxides or nitrides). The sample is mixed in the capsule with ~0.05 g of graphite powder, previously ignited at 2000 °, and placed in the vacuum extraction apparatus together with a piece of Cu or an alloy, which takes the place of an Fee bath. The method of extracting the gas (~1900 °) in the apparatus and the gas analysis, is the same for all solid materials. But in determining O3 in powdered materials, COs is determined with CO, so that its volume contribution cannot be neglected in this case. The method was checked on pure oxide powders and was used for the analysis of surface films on metals, on powdered ferrosilicon and for the determination of O3 in oxide membranes. The method is also applicable to the analysis of oxide and nitride inclusions (in Czech). J. V~clavinek, Hutn. Listy, 16 (7), 1961, 509-512. 37 726. Removal of oxygen in the process of arc vacuum smelting of special steels. U.S.S.R. To explain the mechanism of the purification of a metal from O3 during vacuum arc smelting, experiments on the vacuum arc smelting of low-carbon Fe, deoxidized and nondeoxidized, were carried out. It was shown that the removal of 02 in the form of CO took place only in the smelting of non-deoxidized metal. In the smelting of deoxidized Fe, and consequently of alloy steels, purification from 03 takes place mainly on account of the floating up of non-metallic inclusions and their flotation by bubbles of gas to the surface of the metal bath (in Russian). G. N. Okorokov, A. Yu. Polyakov and A. M. Samarin, Izv. Akad. Nauk SSSR, Otd. Tekh. Nauk, Metallarg. i Toplivo, (3), 1961, 3-9. 37 727. Kinetics of gas evolution in vacuum arc smelting. U.S.S.R. Gas evolution was studied on experimental melts of steels of types St.3, ShKh15, 79NMA, Kh20NS0 and heat resistant alloys based on Ni, in a laboratory vacuum arc furnace with wall crystallizers of 3, 7, 20 and 50 kg capacity. The gases evolved during the melt were collected in a container placed behind a booster pump, and this enabled the change
37 728. Vacuum gas analyser. Manufacturer's announcement, of the Wild-Barfield N.R.C. Model 912. Anon., J. Sci. Instrum., 38 (ll), Nov. 1961, 454 (see also correction, ibid., Dec. 1961, p. 519). 37 729. Az ac61 v~kuumban val6 6nt6senek csepeli tapasztalatai. (Experience of vacuum pouring of steel at the Csepel steelmelting works.) Hungary. Vacuum pouring from ladle to ladle was performed with the aim of decarburizing transformer and acid-resistant steel. The increased corrosion resistance due to decarburization is not sufficient to abandon the use of Ti additions to acidresistant steels. A study was made of the effect of vacuum on ingot structure, hardness and technological properties of steel. It was found that production of large castings in a vacuum is not desirable because of the large segregation of S, P and alloying elements (Cr, Mn), as a result of which a~ decreases with increasing oo. Vacuum treatment was found to have no effect on the quality of tubular components. Strip from vacuumtreated steel had higher ~b and 8. Vacuum treatment did not affect the hardenability of steel or the amount of non-metallic inclusions (in Hungarian). L. Sz6ke, Kohdsz. Lapok, 94 (4), 1961, 151-156. 37 730. Topography of oxidized graphite crystals. Great Britain. F r o m a recent study of gas-solid reactions, it appears that chemical reactivity depends markedly on the nature and density of crystal imperfections. In the case of graphite, both optical and electron microscopy have shown that oxidation often commences at surface atoms and proceeds in a direction perpendicular to the basal plane, forming well defined hexagonal pits. The authors have investigated this pit formation further and conclude that attack by oxygen is favoured by a lattice defect known as screw dislocation in the graphite crystal. Pronounced differences in the mode of graphite attack by oxygen and by carbon dioxide were noted. Pretreatment by hydrogen also affected the mode of subsequent oxidation. These factors are being investigated further, w.J.s. E. E. G. Hughes and J. M. Thomas, Nature, Lend., 193 (4818), 3 March 1962, 838-840. 37 731. The behaviour of components of complex alloys during fusion in vacuum induction furnaces. U.S.S.R. The behaviour of the components of Ni-based alloys containing up to 10 per cent Cr was investigated. It was