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Volume 41 (1993)
- Issue 6 Pages 297-
- Issue 5 Pages 253-
- Issue 4 Pages 191-
- Issue 3 Pages 159-
- Issue 2 Pages 73-
- Issue 1 Pages 5-
Volume 41, Issue 6
Displaying 1-7 of 7 articles from this issue
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REVIEW
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Eiichi KATO1993 Volume 41 Issue 6 Pages 297-316
Published: 1993
Released on J-STAGE: July 20, 2007
JOURNAL FREE ACCESSThe application of the Knudsen cell-mass spectrometer technique to the thermodynamic studies of alloys and oxide melts which are called metallurgical slags is discussed in this review paper. Particular attention is paid to the development of such studies during the last twenty years.
In conducting mass spectrometric studies on the composition dependency of properties of mixtures, a sereies of measurements with the samples of different compositions are necessary, and in these measurements small changes in the instrumental sensitivity between experiments is unavoidable. Various methods have been developed in order to overcome this problem. Many alloy systems have been studied employing ion intensity ratio methods. Analytical expression of thermodynamic functions have enabled to compute the thermodynamic functions from the mass spectrometric data more accurately. The experimental technique of multi-Knudsen cell has been improved, and pulse-counting technique was used for the measurement of ion intensity. The determination of the thermodynamic properties of the alloys containing the components of very low vapor pressure were performed. There are many difficulties in conducting mass spectrometric studies with oxide melts, but some of such systems have been studied by applying various techniques. The phase boundaries of some alloy systems were determined using the data of activities or using another technique. A complete listing of the applications to date is presented.View full abstractDownload PDF (1348K)
INTEGRATED PAPER
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Studies on Chemical Thermodynamics of Hyperlithiated Molecules by Knudsen-Effusion Mass SpectrometryHiroshi KUDO1993 Volume 41 Issue 6 Pages 317-328
Published: 1993
Released on J-STAGE: July 20, 2007
JOURNAL FREE ACCESSExperimental evidence for the existence of polylithiated molecules such as CLi6, Li3O, Li4O, Li3S, Li4S, and Li4P has been obtained by means of Knudsen-effusion mass spectrometry. These polylithiated molecules with nine or more of valence electrons are called hyperlithiated or hypervalent molecules; violating at least formally the octet rule. The dissociation energies, atomization energies and ionization energies of these hyperlithiated molecules were determined. The experimental values agreed fairly well with the theoretical values, and the theoretical prediction that hyperlithiated molecules were thermodynamically more stable than corresponding octet molecules such as CLi4, Li2O, Li2S, and Li3P was verified through a series of experimental work.View full abstractDownload PDF (683K)
REGULAR PAPERS
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Susumu KUROSAWA, Takashi OKA, Masaru YASUMOTO, Shinzo UETA, Nobuo MORI ...1993 Volume 41 Issue 6 Pages 329-334
Published: 1993
Released on J-STAGE: July 20, 2007
JOURNAL FREE ACCESSA thermodynamic study of the vaporization of U-0.3 at%Fe alloy was performed by using the Knudsen-effusion mass spectrometric method in the temperature range of 1,780~2,180 K. Vapor pressures of U and Fe were determined as a function of temperature and the activity coefficients were derived which were compared with the activity coefficients calculated from phase diagrams. Both experimental and calculated values of Fe activity coefficient were considerably small and agreed well with each other, suggesting the estimation method of this study to be appropriate.View full abstractDownload PDF (360K) -
Tsuneo MATSUI, Hideaki INABA1993 Volume 41 Issue 6 Pages 335-342
Published: 1993
Released on J-STAGE: July 20, 2007
JOURNAL FREE ACCESSThe vapor pressures over manganese zinc ferrites with two kinds of oxygen contents (Mn0.676Zn0.261Fe2.063O4.031 and Mn0.676Zn0.261Fe2.063O4.000) were measured by mass-spectrometric method in the temperature ranges of 1,270~1,417 K and 1,258~1,398 K, respectively. As the main gas species over Mn0.676Zn0.261Fe2.063O4.031, three gas species of Zn(g), FeO(g), and MnO(g) were identified in order of decreasing partial vapor pressure. On the other hand, two gas species of Zn(g) and MnO(g) were only identified over Mn0.676Zn0.261Fe2.063O4.000. From the partial vapor pressures of Zn(g), FeO(g), and MnO(g) experimentally obtained in this study and the partial oxygen pressures for the specimen estimated according to the relation between composition and partial oxygen pressure previously reported, the partial vapor pressures of ZnO(g), Fe(g), and Mn(g), which were not detected experimentally, were calculated on the basis of the gas equilibria: MO(g)=M(g)+1/2O2(g), where M=Zn, Fe, and Mn. The manganese zinc ferrites with the compositions of Mn0.676Zn0.261Fe2.063O4+x(x=0.031 and 0.000) were concluded to be the incongruently vaporizing compositions, of which preferentially vaporizing species is Zn(g). The dependence of the vapor pressures on oxygen nonstoichiometry was determined. The enthalpies of vaporization of ZnO(g), MnO(g), and FeO(g) over ferrites were compared with those over ZnO(s), MnO(s), and Fe2O3(s), respectively.View full abstractDownload PDF (490K) -
Eiji ICHISE, Kentaro SHAW, Seiichi TANIGUCHI1993 Volume 41 Issue 6 Pages 343-350
Published: 1993
Released on J-STAGE: July 20, 2007
JOURNAL FREE ACCESSDetermination of activity coefficients of liquid Co-Cr, Co-Ni, and Cr-Ni alloy systems was carried out by means of high temperature Knudsen cell mass spectrometry. Measurements of ion intensities of components of alloys were made within liquid phase compositions at temperatures ranging from 1,723 to 1,873 K. The behavior of the ratio of the activity coefficients with composition derived from ion intensity measurements for all the alloys studied indicates that activity coefficients of these alloys obey the quadratic formalism. Activity coefficients are given in the form of quadratic formalism. In particular, liquid Co-Ni alloy behaves as the regular solution with slightly positive enthalpy of mixing.View full abstractDownload PDF (459K) -
Yukitomi UEDA, Kazuyoshi MAEKAWA, Toshio OISHI, Katsutoshi ONO1993 Volume 41 Issue 6 Pages 351-357
Published: 1993
Released on J-STAGE: July 20, 2007
JOURNAL FREE ACCESSThe activities and partial molar heats of mixing were determined in a liquid Cu-Nd system at 1,600 K using a Knudsen cell and a quadrupole mass spectrometer. The ion intensity ratio for the alloy components was measured for the system and the thermodynamic values were calculated using a modified Gibbs-Duhem equation. The liquid Cu-Nd system shows strong negative deviations from ideal behavior. The partial and integral molar heats of mixing are compared with values in the literature.View full abstractDownload PDF (338K) -
Mitsuru ASANO, Yutaka YAMAMOTO, Noriaki SASAKI, Toshio HARADA, Yasuo M ...1993 Volume 41 Issue 6 Pages 359-369
Published: 1993
Released on J-STAGE: July 20, 2007
JOURNAL FREE ACCESSThe reaction between SrO(s) and W(s) at high temperatures has been studied by a technique of mass-spectrometric thermal analysis. It is found that the vaporization caused by the reaction proceeds in three stages. In the first stage, the gaseous product Sr(g) appears above 1,285 K, leaving the solid product SrWO4(s). In the second stage, the vaporization of Sr(g) occurs again above 1,580 K from the residual SrO(s) unreacted with W(s) during the course of the first stage. In the third stage, SrWO3(g), SrWO4(g), and small Sr(g) vaporize from SrWO4(s). The areas under the curves of the mass-spectrometric thermal analysis have been calculated by a modified integration method. From these areas the apparent partial pressure of Sr(g) in the first stage and also the molar ratio of the gaseous and solid reaction products Sr(g) and SrWO4(s) have been determined. Furthermore, the apparent pressures of SrWO3(g) and SrWO4(g) in the third stage have been obtained by a sensitivity calibration method.View full abstractDownload PDF (674K)
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