Phase Transformations in Dicalcium Silicate: II, TEM Studies of Crystallography, Microstructure, and Mechanisms

Kim, Young Joong; Nettleship, Ian; Kriven, Waltraud M.

doi:10.1111/j.1151-2916.1992.tb05593.x

Cited by 97 publications

(68 citation statements)

References 29 publications

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“…The fact that (100) twinning was observed all over the samples is in agreement with the observations of Kim et al (1992) on/3 phases synthesized at high-temperature and ambient-pressure conditions. In this study, the (001) twin is seldom observed; this is also in agreement with Kim et al (1992) who report that 90% of the observations are (/00) twins, the remaining 10% being (001). Groves (1983) and Ghose et al (/983) reported the presence of (100) twin boundaries only.…”

Section: High Pressure High Temperature Experimentssupporting

confidence: 90%

“…requires only a small thermal activation, since it can be performed even at ambient temperature. Two mechanisms have been proposed for the/34 7 transition which occurs during cooling at room pressure: reconstructive (Eysel and Hahn 1970) or displacive (Barbier and Hyde 1985;Kim et al 1992). Our high pressure experiments as well as that of Hanic et al (1987), all performed at room temperature suggest that a mechanism with a low activation energy such as the displacive one, is at least possible.…”

Section: High Pressure Experiments At Room Temperaturementioning

confidence: 49%

“…1 (Yannaquis and Guinier 1959;Smith et al 1961 ;Niesel and Thormann 1967;Eysel and Hahn 1970;Groves 1983;Eberhard et al 1991;Barbier and Hyde 1985;Kim et al 1992). /~-Ca2SiO4 appears in the stability field of the 7 modification on cooling and is usually called metastable because it never forms during heating.…”

Section: Introductionmentioning

confidence: 96%

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High pressure polymorphism of dicalcium silicate Ca2SiO4. A transmission electron microscopy study

1995

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Abstract. Ca2SiO 4 dicalcium silicate has been transformed at high pressure in a diamond-anvil cell (DAC) coupled with a YAG laser heater, in order to study the high-pressure modifications of this compound. Starting material was the olivine form of CazSiO 4 (7-polymorph). Several samples have been synthesized at loading pressures of 4.5, 10 and 15 GPa respectively, at room temperature. Other samples have been obtained at:pressures ranging between 4.5 and 45 GPa and temperatures estimated to be about 2500 ~ The study of the quenched high pressure and/or high temperature phases has been performed using analytical transmission electron microscopy (ATEM) and X-ray diffraction (XRD). All the polymorphs of Ca2SiO 4 usually produced with high temperatures, including ~-CazSiO4, have been observed in the samples recovered from the high-pressure experiments. The c(-CazSiO 4 and ~-CaaSiO 4 polymorphs have been obtained at ambient conditions for the first time without stabilizing impurities. A new modification of ~'-Ca2SiO 4 has also been synthesized. Finally, the breakdown at high-pressure and temperature of Ca2SiO 4 into CaSiO 3 and CaO is reported.

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Section: High Pressure High Temperature Experimentssupporting

confidence: 90%

Section: High Pressure Experiments At Room Temperaturementioning

confidence: 49%

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High pressure polymorphism of dicalcium silicate Ca2SiO4. A transmission electron microscopy study

1995

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“…1). According to the lattice cor respondence between the two phases, a becomes aL, b becomes 1/3cL, and c becomes bL.7), 8) The to-L trans formation is accompanied by the very small volumetric ex pansion of 0.3%, in accord with previous studies.6), 2.2 Principal distortions and habit planes We assume that, upon to-L transformation, the phase lattice is homogeneously distorted into the L-phase lattice. The magnitudes and directions of the principal dis tortions ( are therefore given by the eigenvalues and eigenvectors of the following equation :11) (1) The matrix (OCM), representing the lattice correspond ence between the monoclinic -phase (M) and the ortho rhombic L phase (), is given by…”

Section: Introductionmentioning

confidence: 99%

Phenomenological Anlaysis of Martensitic Transformation in Dicalcium Silicate.

Fukuda

2000

J. Ceram. Soc. Japan

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Matrix algebra analysis of martensitic transformations has been employed for the determination of habit planes and shape deformations of Ca2SiO4 upon totransformation during heating. The cell parameters of both the parent and product L-phases at the transformation temperature (710) have been found from extrapolation of the regression of their cell-parameter variations. The analysis indicates that one of the prin cipal distortions (=cL/3b) of the lattice deformation is equal to unity, and the other principal distortions are larger and smaller than unity. This satisfies the requirement for the formation of completely coherent interfaces between the two phases, which are almost parallel to either (100) or (001) Because the trans formation involves a very small volumetric expansion of 0.3%, the strain accommodation would be almost completed. Both the complete coherency at the interphase boundaries and the effective strain accommoda tion probably lead to the thermoelasticity of the transformation, in accord with a previous study for doped Ca2SiO4.[ and their cell parameters at the transformation temperature. Because the accuracy of the latter is essential to the reliability of the calculation results, they were determined for the crystals in which the two phases coexist. By virtue of the constraint represented by the equation 3b=cL, one of the three principal distortions of the lattice deformation was equal to unity. The other two principal distortions satisfied the requirement for the forma tion of coherent interphase boundaries between the two phases. The coherency as well as the effective strain accom modation have strongly suggested the thermoelasticity of the transformation. The predictions were in good agree ment with the actual experimentally determined shape deformation.3)The thermoelasticity of C2S solid solutions has been con firmed based on the growth and shrinkage behavior of the martensite plates during cooling and heating.3) The thermal hysteresis (As-Ms) was negative, where AS and MS are the starting temperatures of the reverse (to-L) and for ward transformations, respectively.3)-5) Because of the athermal nature of the transformation, the amount of trans formation remains unchanged when the temperature is kept constant. Thus, the L and -phases coexist within the tem perature intervals between Ms and Mf during cooling and between A and Af during heating, where Mf and Af are the finishing temperatures of the forward and reverse transfor mations, respectively. These transformation temperatures have been successfully determined by high-temperature X ray diffractometry (HT-XRD) and high-temperature opti cal microscopy.3)-5)With pure C2S, the thermoelasticity of the L marten sitic transformations is still uncertain. Recently, Remy et al.6) have determined the temperature dependence of the

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“…Under slow cooling process, α-C2S undergoes a polymorphic solid-phase transition to β-C2S, which then partially or fully transitions to γ-C2S. The difference in crystal structure and density between β-C2S and γ-C2S results in high internal stress, causing disintegration of the slag into a powder and an accompanied volume increase [13,14]. However, rapid quenching freezes C3S and hence prevents formation of C2S.…”

Section: Lmf Slagsmentioning

confidence: 99%

Recent Developments in Dry Slag Granulation: A Path to Improving Safety and Sustainbility of the Metallurgical Sector

Faucher¹,

Mostaghel²,

So³

et al. 2017

Anais Do Congresso Anual Da ABM

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Molten slag from pyrometallurgical furnaces is tapped at high temperature, carrying a large amount of thermal energy. But the common slag dumping and water granulation methods used for slag treatment do not permit energy recovery. Furthermore, water is present in these processes and while operations are designed to minimize risks of steam explosions, from the contact of slag with water, these common slag handling practices have never been inherently safe. Common handling practices do permit some slags to be sold, but often in low volumes at low prices. Dry granulation offers advantages over these common slag handling practices, including the production of by-products, the recovery of thermal energy, and the eliminated consumption and safety hazards of water. For these reasons, there have been various studies in dry granulation and heat recovery, but most have never been brought to commercial scale due to scalability and cost challenges. EcomaisterHatch has developed and brought to commercial scale a reliable and simple dry granulation and heat recovery technology. Here we review common slag handling practices, the developments in dry slag granulation over the last three decades, introduce the Ecomaister-Hatch dry slag granulation process, and elaborate on future applications of the technology in the processing of argon oxygen decarburization and blast furnace slags.

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Phase Transformations in Dicalcium Silicate: II, TEM Studies of Crystallography, Microstructure, and Mechanisms

Cited by 97 publications

References 29 publications

High pressure polymorphism of dicalcium silicate Ca2SiO4. A transmission electron microscopy study

High pressure polymorphism of dicalcium silicate Ca2SiO4. A transmission electron microscopy study

Phenomenological Anlaysis of Martensitic Transformation in Dicalcium Silicate.

Recent Developments in Dry Slag Granulation: A Path to Improving Safety and Sustainbility of the Metallurgical Sector

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