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405 results on '"Jokilaakso, Ari"'

16. Production of Nitrogen‐Alloyed Stainless Steels in Argon Oxygen Decarburization Converter: Kinetics and Modeling of Nitrogenation and Denitrogenation.

Author

Pitkälä, Jyrki, Holappa, Lauri, and Jokilaakso, Ari

Abstract

The study aims to comprehend the behavior of nitrogen in the argon oxygen decarburization (AOD) process during the production of nitrogen‐alloyed stainless steels, where the precise adjustment of nitrogen content plays a crucial role in enhancing productivity. Furthermore, the objective is to investigate the rate of change in nitrogen content when blowing a mixture of nitrogen and argon, instead of using pure nitrogen or argon alone. Hence, both nitrogenation and denitrogenation cases are examined, and kinetic models are developed. While solution thermodynamics can predict the final nitrogen content, the kinetics are influenced by the gas flow rate, steel temperature and composition, and levels of the surface active elements in the steel. By integrating a previously developed thermodynamic equilibrium equation with the kinetic models, nitrogen contents in the range of 0.150–0.400% can be reliably predicted. Consequently, the equations can be applied to predict nitrogen content during both the nitrogenation and denitrogenation stages in the reduction and desulfurization phases of the AOD process. [ABSTRACT FROM AUTHOR]

Published
2024
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17. Phase equilibria of the Na2O‐TiO2‐SiO2 system between 900 and 1600°C in air.

Author

Santoso, Imam, Sibarani, David, Hidayat, Taufiq, Zulhan, Zulfiadi, Sukhomlinov, Dmitry, Chen, Min, Klemettinen, Lassi, Taskinen, Pekka, Lindberg, Daniel, and Jokilaakso, Ari

Subjects
PHASE equilibrium, THERMODYNAMICS, ELECTRON probe microanalysis, SOLID-liquid equilibrium, PHASE diagrams, LIQUIDUS temperature
Abstract

The Na2O‐SiO2‐TiO2 system is important for the glass, ceramic, and metallurgical industries. Its features provide information on the composition and melting temperature to be utilized during the production of glass and ceramic and during the processing of TiO2‐bearing material in the metallurgical industry. The liquidus temperatures between 900 and 1600°C in the ternary system at saturation of solid SiO2, TiO2, Na2Ti6O13, Na2SiTiO5, and Na2Ti3O7 were measured using the equilibration‐quenching energy‐dispersive X‐ray spectroscopy/Electron Probe Microanalyzer technique. A wide range of liquidus compositions were obtained with Na2O between 0 and 41.7 mol% in the SiO2‐ and TiO2‐rich regions. The present study provides liquidus data at 1500 and 1600°C for the first time. Liquidus temperatures at various double saturations were also obtained in the present investigation to determine univariant lines in the phase diagram. The present experimental data were compared with previous investigations and computed phase diagrams. The data obtained in the present investigation can be employed to optimize the thermodynamic properties and phase diagrams of the Na2O‐SiO2‐TiO2 system. [ABSTRACT FROM AUTHOR]

Published
2024
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