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Wyszukujesz frazę "oxygen activity" wg kryterium: Temat


Wyświetlanie 1-3 z 3
Tytuł:
Oxygen Activity in Melts of Fe-C-Cr-Ni Based Alloys
Autorzy:
Záděra, A.
Dulava, M.
Pernica, V.
Kaňa, V.
Powiązania:
https://bibliotekanauki.pl/articles/381686.pdf
Data publikacji:
2016
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
oxygen activity
polycomponent solution
thermodynamic equilibrium
activity coefficient
aktywność tlenu
równowaga termodynamiczna
współczynnik aktywności
Opis:
Oxygen is an element that is first purposely brought into the steel melt to remove some unwanted elements or to reduce their concentration (oxidation). In the made cast steel there is on the contrary necessary to reduce the oxygen content with the use of deoxidation to such a level in order to avoid a reaction with carbon with the formation of CO bubbles. Concentration of oxygen in steel before casting is given, in particular, by the manner of metallurgical processing and the used deoxidation process. Oxygen is found in molten steels both as chemically bound in the form of oxides and in the form of oxygen dissolved in the solution – the melt. Chemical composition of the melt strongly influences the activity of oxygen dissolved in the melt and further on the composition of oxidic inclusions forming in the melt during the reaction with oxygen. In the Fe-C-Cr-Ni based alloys in the reaction with oxygen greatly participates also chrome, whose products are often in solid state and they are the cause of forming such defects as e.g. oxidic films.
Źródło:
Archives of Foundry Engineering; 2016, 16, 4; 181-186
1897-3310
2299-2944
Pojawia się w:
Archives of Foundry Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Contribution to Deoxidation of Austenitic Steels in a Vacuum Induction Furnace with Carbon
Autorzy:
Šenberger, J.
Pernica, V.
Powiązania:
https://bibliotekanauki.pl/articles/379906.pdf
Data publikacji:
2015
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
vacuum induction furnace
deoxidation
carbon
austenitic steel
petrochemistry
oxygen activity
total oxygen
próżniowy piec indukcyjny
odtlenianie
węgiel
staliwo austenityczne
petrochemia
aktywność tlenu
Opis:
Deoxidation of steel with carbon under reduced pressure is often used for increasing the steel purity. Suitable units for this purpose in foundries are vacuum induction furnaces. Possibilities of increasing the steel purity by deoxidation with carbon in the vacuum induction furnace were studied for the steel for the petrochemistry of specific composition 25Cr/35Ni. The charge composed of the return material only was melted in the air. During melting the charge oxidized and the oxidizing slag formed. Chemical composition of steel, morphology, chemical composition of inclusions in the steel and chemical composition of slag after vacuuming were studied on the basis of samples taken before and after vacuuming. Temperature and oxygen activity were measured before and after vacuuming. Globular inclusions with dominant content of silicon and manganese were observed in steel before and after vacuuming. Contents of total oxygen in steel didn’t change significantly during vacuuming. On the basis of composition of inclusions and measured oxygen activity the activity of Cr2O3 in inclusions was calculated. A slag sample was taken after vacuuming and equilibrium oxygen activity in steel with regard to the Cr2O3 content in the slag was estimated from the slag composition. Equilibrium oxygen activity in relation to the Cr2O3 content in the slag was higher than equilibrium activity measured in the steel. For this reason it is not possible, under the studied conditions, to decrease oxygen content in steel during vacuuming.
Źródło:
Archives of Foundry Engineering; 2015, 15, 2; 105-109
1897-3310
2299-2944
Pojawia się w:
Archives of Foundry Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Thermodynamic analysis of cast irons solidification with various types of graphite
Autorzy:
Elbel, T.
Hampl, J.
Powiązania:
https://bibliotekanauki.pl/articles/380412.pdf
Data publikacji:
2012
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
pomiar aktywności tlenu
energia swobodna Gibbsa
krzepnięcie żeliwa
continuous oxygen activity measurement
calculation of Gibbs free energy
cast iron solidification
Opis:
The contribution summarises the results of oxygen activity determinations, which were measured and registered continuously in castings from cast irons with various types of graphite. The results were used to find the relationship between two variables: natural logarithm of oxygen activities and reverse value of thermodynamic temperature 1 /T. Obtained regression lines were used to calculate oxygen activity at different temperatures, to calculate Gibbs free energy \deltaG at the different temperatures and to calculate the single \deltaG value for significant temperature of the graphite solidification. The results were processed by a statistical analysis of data files for the different types of graphite with flake, vermicular and spheroidal graphite. Each material has its proper typical oxygen activities range and individual temperature function of Gibbs free energy for analysing and governing casting quality.
Źródło:
Archives of Foundry Engineering; 2012, 12, 4; 157-165
1897-3310
2299-2944
Pojawia się w:
Archives of Foundry Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-3 z 3

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