Using a pure Al2O3 crucible, authors measured the following reaction under the conditions of 3 Al2O3· SiO2, Al2O3 or 3CaO·Al2O3 saturation at the temperatures of 1, 550° and 1, 600°C;Further, the activities of SiO2 in the molten slags of SiO2-CaO-Al2O3 ternary system were calculated from the equilibrium values of Si in molten iron at a given temperature and gas ratio PH2/PH2O, where the pure β-cristobalite was taken as the standard state. The authors illustrated the relation of the equi ibrium among Si in molten iron, activity of SiO2 of the SiO2-CaO-Al2O3, molten slag saturated with Al2O3 and H2-H2O mixed gas.Finally, authors determined the liquidus lines in the presence of molten iron at temperatures of 1, 500° and 1, 600°C on the Al2O3 side of SiO2-CaO-Al2O3 ternary diagram from the equilibrium compositions of slags.
The interaction between oxygen and phosphorus in molten iron was studied by a method of equilibrating molten Fe-P alloys with a mixture of hydrogen and water-vapor at a given ratio.The composition of the gas mixture was so determined that slag was not formed. In order to examine the effect of temperature on the interaction parameter e (p) o, experiments were performed at three different temperatures of 1540°C, 1585°C. and 1625°C, but there was almost no difference within the experimental errors.The interaction parameter e (p) o (=∂logf (p) o/∂ [%P]) calculated from the present results was approximately +0.06 at an average temperature of 1585°C.
Constructing the following electrode concentration cell, authors measured electromotive force corresponding to the change of silicon content in iron by a potentiometer.The temperature range of the experiment was 1, 520-1, 530°C and for measurement of the temperature a Pt-Pt-Rh thermocouple was used. As preliminary experiments, the reversibility and thermoelectromotive force were investigated.The theoretical relation between electromotive force E and the activity of silicon aSi was as follows:where a'Si: the activity of pure siliconaiSi: the activity of silicon ion in the molten slag.Because pure silicon was selected as a standard state, then the following equation was obtained from eqn. (1)n was approximately determined as n 4 by calculation from the authors' data.The activity of silicon was obtained by substituting the values E, n and T to eqn. (2).Being judged from this result, Fe-Si binary solution was recognized to be a semi-regular solution and obeyed to Henry's law up to about nSi=0.10Furthermore, the free energy change ΔG01, 793 of the following reaction at 1, 520°C was calculated from the author's data.ΔG01, 793 represented the free energy of solution of silicon at unit activity on a scale in which the activity was equal to percentage at infinite dilution. To convert this to activity on a mole fraction scale in which the activity of pure liquid silicon was unity, the following eqn. (4) was requiredFrom the relation between log(ASi/nSi=γSi) and square of the mole fraction of iron n2Fe, activity coefflcient γ0Si which represented γSi at nFe=0 was obtained as 0.013. and the mole fraction of silicon in dilute solutions was 0.0199 times its weight percentage. From these two values, the ratio of the activities of silicon on the two scales was obtained as 0.00026.Substituting this value to eqn. (4), authors obtained the following value
Physicochemical behav ior of a lloying eleme nts in molten iron has become the subject of numerous investigations during t he past 25 years.Conseq uentl y, interactions of elements dissolved in th e iron-rich solution , such as Fe-C-X, Fe-H-X , Fe-O-X and Fe-S-X where X represents a n alloying element , ha ve gradually come to be better unde rstood .T hese effects are expressed by the interaction parameter of Wag ner as follows:where r; is the activit y coefficient of compo ne nt i and N ) is the mole fraction of component i. Fundamental thermod ynami c re lations such as the interaction parameter, the re lationship between e/ and e/' ( = 8 10gf;8( °biJ) etc. a re briefl y explained.A brief s umma ry is made of many laborator y work s in Japa n and other countries on the physical c hemistry of iron a nd steel mak ing, es peciall y for Fe•C-X and F e•N•X systems and some discussions are made on the relationship between interaction parameter and the atomic number of alloying eleme nts, wh ich follows a regular periodic pattern .
Using a CaO crucible, authors measured the equilibrium the following reaction under the conditions of 2CaO·SiO2, 3CaO·SiO2 or CaO saturation at the temperatures of 1550° and 1700°C, At the reaction (1), the equilibrium constant became as follows.Further, as already published in the first report, the reaction and the equilibrium constant at the system, saturated by SiO2 were given respectivelly as follows.If the activity of pure SiO2 was taken to unity as the standard state of αSiO2, K and Ks ought to be equal at a given temperature, thus, αSiO2 in the slag of SiO2-CaO-Al2O3 system was calculated from following equation;Finally, authors determined the liquidus at the temperatures of 1550°C and 1600°C on the CaO side of SiO2-CaO-Al2O3 ternary diagram from equilibrium compositions of slag.
To ciarijl' Ihe a/l/Jlicabilily of gaseolls melal.forIhe /lllriJicalion o.f liquid iron and sleel , a SllU!V was made on Ihe deoxidalion wilh Ar-Ca gas bubbles floaling u}J in iron melt.The /lreselll slllqV will also give some informations 011 Ihe behavior o.f com/llex deoxidi::er culliaining calcilllll.The resulls oblailled are as .follows:(J) ilt 1550 C, Ihe inleraclion /Jammelel's were <:•u)= -535 and e~~)= -t 330, Ih e equilibrillm cOllslant for Ihe reaclion of lea I + 1 0 I = CaO was log K ('n = log a"naO = -9.82.and Ihe equilibrium rela lioll belween Ihe iron melt and Ihe calcium va/Jor was log I"" Ca H 0" 0 II P(, . ., (aim) 3.86.(2) The decrease in 101 was direclfy /)I'o/Jorlional 10 Ihe amoulIl ~f calcillll!added in the rallge ~f high ox)'gell conlenl ((OJ > 150 /J/)lII) find was ex/nesser!by an eX/Jollenlialjzlllction o.f it in Ihe range fl.f low oxygen cOlllellt (101 < tOO/1/1m ).'Filis /,henomenon is inlerpreled as follows; Ihe deoxidalion /Hocess is cOlllrolled by Ihe sUNJ(v ~f calcium from Ihe bubble side 10 Ihe reaction ::olle in Ihe former find ~v Ihe SU/J/1fy ~f ox),gen .fromIhe b1llk of melt 10 Ihal ::o"e in the laller case.(3) The increase in Ihe floaling distance of AI' Ca bubbles ill Ihe lIletal balh raised Ihe efficiclI~)' of calcillm 1IIili::(llioll.
The equilibrium of gaseous H2O-H2 mixture with liquid iron-niobium alloys contained in alumina crucible shows that the activity coefficient of oxygen is moderately deminished by niobium. The oxide in equilibrium with the melt is not including iron and aluminum and considered to be NbO2 (s). The equilibrium constant at 1600°C is [%Nb]·[fO·%O]2=2·3·10-4 where log fO=-0.06.[%Nb]. The deoxidizing power of niobium is comparable to that of vanadium.
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