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Investigation of the thermodynamics of metallurgical reactions
206
h~ternational Conference on Radioisolopes in Scientific Research
70 I n v e s t i g a t i o n of the T h e r m o d y n a m i c s of M e t a l l u r g i c a l R e a c t i o n s . L . A . SCHWARZMAN, U . S . S . R . The study of the thermodynamics of metallurgical reactions is important both for improvement of industrial techniques and for extension of our knowledge in the field of the physical chemistry of molten media. The report presents methods of investigation based on the use of radioactive isotopes and comnmnicates some of the results of these investigations. Two directions of thermodynamic investigations are examined, namely, the study of distribution equilibria of elements between liquid iron and slags of various compositions (work carried out at the Central Iron and Steel Research Institute), and the determination of the thermodynamic activity of the elements dissolved in the liquid iron (work carried out at Moscow Steel Institute). In the first direction methods have been developed in which radioactive isotopes are introduced either into the metal or into the slag. Equilibrium is thus set up both for the passage of elements from the metal into the slag and for the reverse passage. The advantages of the use of radioactive isotopes may be summed up as follows: (1) Possibility of carrying out investigations with very low concentrations of elements, at which both the metallic and slag melts may be regarded as infinitely dilute solutions; (2) Speed and reliability of determination of the concentrations of elements in metal and slag samples. In the experiments the distribution coefficients of the elements as between metal and slag of constant composition were determined from radioactivity measurements as functions of the temperature. The thermodynamic functions of the transition reactions of phosphorus, sulplmr, chromium, tungsten and molybdenum from iron into slags were determined by this method. The partial pressures of vapours of refractory substances and of the components of liquid metallic melts can be determined only by using radioactive isotopes, as the quantities of these evaporated substances are so small that they cannot practically be determined by chemical analysis. The methods which have been developed have made it possible to study the thermodynamic properties of solutions of sulphur, phosphorus, chromium and silicon in liquid iron. : \ simple method of determining the thermodynamic activity of elements dissolved in liquid iron by measuring the radioactivity of refractory plates has been developed and was used for the determination of the thermodynamic activity of sulphur in liquid cast iron.
71
An A s s e s s m e n t Trial of the Q u a l i t y of R e f r a c t o r y M a t e r i a l s U s e d in C a s t i n g Pit and the D i s t r i b u t i o n of N o n - m e t a l l i c I n c l u s i o n s in Steel by M e a n s of R a d i o active T r a c e r s . TADEUSZ ~ A L K I E V v ' I C Z ~ ROMAN ~rUSATOWSKI et al., I n s t i t u t e o f Metallurgy, Gliwice, Poland. An attempt has been made to investigate the distribution and amount of non-metallic inclusions originating from refractories used in casting pit by means of radioisotopes Fe ~9. The radioisotope in the form of F % O a has been introduced into the fireclay batch used for brick making. Ingots and blooms of steel for deep drawing have been investigated by autoradiographie methods and measurement of radiation intensity. For comparison of different refractories used for runner bricks two ingots in each runner made of different fireclay have been poured. Fireclay batch giving brick with refractoriness 1510, 1690, 1750°C respectively has been used. The investigations have shown, that regardless of the kind of refractories used in given mould and hot top the non-metallic inclusions originating from runner bricks remained mostly in the body of the ingot remaining afler discarding crops. Runner bricks with the lowest refractoriness have given tim most uniform distribution of inclusions along the ingot and the lowest mean radiation intensity. The poorest results were obtained with runner bricks having the highest refractoriness. The pattern of distribution of inclusions in the ingot has the form of a paraboloid in the head of ingot with shape similar to solidification isotherms. In the ingot butt another shorter paraboloid with its vertex towards the top of ingot was observed. The examination of the fractures of blooms have shown that the radioactive inclusions were mostly distributed in a zone embedded up to 7 m m below the surface. The depth of this zone increased towards the top of ingot. The results relating to the quality ofdifI'erent type of refractories obtained by Use of radioactive tracers have been confirmed by statistical control of deepdrawn products. 72
I n v e s t i g a t i o n of the A c t i o n of Modifyinl~ A g e n t s in F l o t a t i o n b y M e a n s of R a d i o active T r a c e r s . O . S. BOG~ANOV, V. J . HAINMAN, N. A. YANIS, A. K. PODNEK, U.S.S.R. The report demonstrates the very promising prospeets of applying the radioactive tracer method to the
h~ternational Conference on Radioisolopes in Scientific Research
70 I n v e s t i g a t i o n of the T h e r m o d y n a m i c s of M e t a l l u r g i c a l R e a c t i o n s . L . A . SCHWARZMAN, U . S . S . R . The study of the thermodynamics of metallurgical reactions is important both for improvement of industrial techniques and for extension of our knowledge in the field of the physical chemistry of molten media. The report presents methods of investigation based on the use of radioactive isotopes and comnmnicates some of the results of these investigations. Two directions of thermodynamic investigations are examined, namely, the study of distribution equilibria of elements between liquid iron and slags of various compositions (work carried out at the Central Iron and Steel Research Institute), and the determination of the thermodynamic activity of the elements dissolved in the liquid iron (work carried out at Moscow Steel Institute). In the first direction methods have been developed in which radioactive isotopes are introduced either into the metal or into the slag. Equilibrium is thus set up both for the passage of elements from the metal into the slag and for the reverse passage. The advantages of the use of radioactive isotopes may be summed up as follows: (1) Possibility of carrying out investigations with very low concentrations of elements, at which both the metallic and slag melts may be regarded as infinitely dilute solutions; (2) Speed and reliability of determination of the concentrations of elements in metal and slag samples. In the experiments the distribution coefficients of the elements as between metal and slag of constant composition were determined from radioactivity measurements as functions of the temperature. The thermodynamic functions of the transition reactions of phosphorus, sulplmr, chromium, tungsten and molybdenum from iron into slags were determined by this method. The partial pressures of vapours of refractory substances and of the components of liquid metallic melts can be determined only by using radioactive isotopes, as the quantities of these evaporated substances are so small that they cannot practically be determined by chemical analysis. The methods which have been developed have made it possible to study the thermodynamic properties of solutions of sulphur, phosphorus, chromium and silicon in liquid iron. : \ simple method of determining the thermodynamic activity of elements dissolved in liquid iron by measuring the radioactivity of refractory plates has been developed and was used for the determination of the thermodynamic activity of sulphur in liquid cast iron.
71
An A s s e s s m e n t Trial of the Q u a l i t y of R e f r a c t o r y M a t e r i a l s U s e d in C a s t i n g Pit and the D i s t r i b u t i o n of N o n - m e t a l l i c I n c l u s i o n s in Steel by M e a n s of R a d i o active T r a c e r s . TADEUSZ ~ A L K I E V v ' I C Z ~ ROMAN ~rUSATOWSKI et al., I n s t i t u t e o f Metallurgy, Gliwice, Poland. An attempt has been made to investigate the distribution and amount of non-metallic inclusions originating from refractories used in casting pit by means of radioisotopes Fe ~9. The radioisotope in the form of F % O a has been introduced into the fireclay batch used for brick making. Ingots and blooms of steel for deep drawing have been investigated by autoradiographie methods and measurement of radiation intensity. For comparison of different refractories used for runner bricks two ingots in each runner made of different fireclay have been poured. Fireclay batch giving brick with refractoriness 1510, 1690, 1750°C respectively has been used. The investigations have shown, that regardless of the kind of refractories used in given mould and hot top the non-metallic inclusions originating from runner bricks remained mostly in the body of the ingot remaining afler discarding crops. Runner bricks with the lowest refractoriness have given tim most uniform distribution of inclusions along the ingot and the lowest mean radiation intensity. The poorest results were obtained with runner bricks having the highest refractoriness. The pattern of distribution of inclusions in the ingot has the form of a paraboloid in the head of ingot with shape similar to solidification isotherms. In the ingot butt another shorter paraboloid with its vertex towards the top of ingot was observed. The examination of the fractures of blooms have shown that the radioactive inclusions were mostly distributed in a zone embedded up to 7 m m below the surface. The depth of this zone increased towards the top of ingot. The results relating to the quality ofdifI'erent type of refractories obtained by Use of radioactive tracers have been confirmed by statistical control of deepdrawn products. 72
I n v e s t i g a t i o n of the A c t i o n of Modifyinl~ A g e n t s in F l o t a t i o n b y M e a n s of R a d i o active T r a c e r s . O . S. BOG~ANOV, V. J . HAINMAN, N. A. YANIS, A. K. PODNEK, U.S.S.R. The report demonstrates the very promising prospeets of applying the radioactive tracer method to the