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Volume 29 (2002)
- Issue 5 Pages 192-
- Issue 4 Pages 146-
- Issue 3 Pages 102-
- Issue 2 Pages 58-
- Issue 1 Pages 2-
Volume 29, Issue 4
Displaying 1-7 of 7 articles from this issue
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Tatsuya Shirakami, Akiko Yamada, Ayako Tanifuji, Kazuyori Urabe, Kazuy ...2002 Volume 29 Issue 4 Pages 146-151
Published: September 10, 2002
Released on J-STAGE: September 07, 2009
JOURNAL FREE ACCESSDifferential thermal analyses (DTA) of six slags of different added-CaO content fabricated from municipal waste ash were performed with various heating rates. An endothermic peak caused by glass transition and two exothermic peaks caused by crystallizations were observed for four specimens of low CaO-content. With decreasing the heating rate, the two peaks were superposed on each other. On the other hand, only one crystallization peak was observed for two specimens of high CaO-content. In order to estimate the activation energies of the crystallizations, a modified Kissinger equation was defined by use of the first peak in the derivative of the DTA curve. The obtained activation energies were correlated with basicities of the specimens defined by the JIS, ASTM and Ca/Si. The phases of thoroughly crystallized specimens were identified by X-ray powder diffractometry. Pseudowollastnite, anorthite and albite were main crystalline phases for four specimens of low CaO-content, while gehlenite was only phase for two specimens of high CaO-content. These phases could be explained by the SiO2-Al2O3-CaO ternary phase diagram. Through the analysis of the four partially crystallized low CaO-content specimens, it was found that the phase crystallized initially in the two lower CaO-content specimens was pseudowollastonite, and that of the two higher CaO-content specimens was gehlenite.View full abstractDownload PDF (1180K) -
Analysis of the Heat Capacities of Alkali Metal Chlorides and CorundumTakasuke Matsuo, Nobuki Tanaka, Osamu Yamamuro, Akira Inaba2002 Volume 29 Issue 4 Pages 152-162
Published: September 10, 2002
Released on J-STAGE: September 07, 2009
JOURNAL FREE ACCESSExperimental values of the heat capacity of alkali metal chlorides (LiCl, NaCl, KCl, RbCl and CsCl) and corundum Al2O3 have been decomposed into Cv and (Cp-Cv) contributions by non-linear least squares analysis. The (Cp-Cv) values thus derived are compared with those calculated from the expansivity and stiffness. The agreement is satisfactory for NaCl, KCl, and RbCl. For LiCl and CsCl, the calculated values exceeded those from the heat capacities by 20∼30%. For corundum the difference is of the same magnitude (25%) but in the opposite sign. Possible reasons for the difference are discussed. The fitting procedure used in the analysis has revealed an unexpected tendency in the heat capacity of corundum at higher temperatures (1800∼2250K).View full abstractDownload PDF (1810K) -
Ichiro Hatta2002 Volume 29 Issue 4 Pages 163-172
Published: September 10, 2002
Released on J-STAGE: September 07, 2009
JOURNAL FREE ACCESSIn the study on phase transitions, heat capacity is one of important quantities since at almost all phase transitions heat capacity exhibits anomalous behavior. Phase transitions are characterized by two kinds of categories. One is a continuous transition where the order parameter becomes zero continuously at the transition temperature and the other is a discontinuous transition where the order parameter exhibits a jump at the transition temperature. The former includes so-called a second-order transition and the latter is called a first-order transition conventionally. Within framework of mean field approximation, it can be shown that heat capacity exhibits a jump at a continuous transition. However, in a much higher approximation or an exact solution heat capacity diverges at a continuous transition. In such a case, critical exponents are a useful parameter to know characteristics at a phase transition and scaling relations are also applicable to know self-consistency among critical exponents. It is pointed out that although critical amplitudes have been less noted so far, we have to pay attention to them. At a discontinuous transition, kinetics is important because heterogeneous structures result in it always. There are a lot of materials with microscopic heterogeneous structure which undergoes a state transformation. Dynamic heat capacity measurement is one of promising tools in such a field.View full abstractDownload PDF (1781K) -
Katsunori Yamaguchi, Kimio Itagaki2002 Volume 29 Issue 4 Pages 173-180
Published: September 10, 2002
Released on J-STAGE: September 07, 2009
JOURNAL FREE ACCESSAccurate data for high temperature heat contents and heat capacities of substances are valuable for the study of materials and processes at elevated temperature. The heat contents and heat capacities of solids and liquids above 1000K are determined experimentally by drop calorimetry and the use has been extended to higher temperatures by using modern techniques for measuring and controlling temperature. The general requirements for the drop method are described in terms of furnace assembly, temperature measurement, calorimeter and sample container. Heat capacities can be determined from relative heat content measurements. Shomate function and qusai-local linear regression (QLLR) are useful to accurately derive the heat capacities from the heat contents. Several applications of the heat content measurements are described.View full abstractDownload PDF (2140K) -
2002 Volume 29 Issue 4 Pages 180
Published: September 10, 2002
Released on J-STAGE: September 07, 2009
JOURNAL FREE ACCESSDownload PDF (598K) -
S. Yamamoto2002 Volume 29 Issue 4 Pages 183
Published: September 10, 2002
Released on J-STAGE: September 07, 2009
JOURNAL FREE ACCESSDownload PDF (836K) -
T. Sato, A. Chiba2002 Volume 29 Issue 4 Pages 184-185
Published: September 10, 2002
Released on J-STAGE: September 07, 2009
JOURNAL FREE ACCESSDownload PDF (330K)
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