Papers by Keyword: Calorimetry

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Authors: C.A. Koh, J.L. Savidge, C.C. Tang, R.E. Motie, X.P. Wu, R.I. Nooney, R. Westacott
Authors: Jana Zahálková, Pavla Rovnaníková
Abstract: The production of Portland cement is connected with high emissions of greenhouse gases, especially carbon dioxide, and the intensive consumption of energy and natural resources. The present trend is for the replacement of cement by reactive admixtures, which can include ground waste glass, a material which shows pozzolanic activity. This paper deals with the determination of the mechanical properties of cement pastes in which part of the cement mixture (5 to 30 %) was replaced by borosilicate glass. The process by which the hydration of the cement with ground glass began was monitored by an isothermal calorimeter.
Authors: Tatyana D. Malinovskaya, Roman A. Nefedov, Ouna B. Sambueva, Victor Sachkov
Abstract: The thermochemical processes of synthesis and purification of rare earth metals fluorides through the transfer of fluoroammonium complexes were discussed. By differential thermal calorimetry the temperature maxima of rates of formation and decomposition of complex compounds were defined and the values of the apparent activation energy processes were determined. It is possible the use of fluoroammonium systems to develop the preparation of anhydrous fluorides of rare earth metals.
Authors: Ch. Cunat, France-Anne Kuhnast, A. Aharoune, M. Fiorani, Z. Ayadi
Authors: Hassan Houcin Ktari, Jean Philippe Couzine, Julie Bourgon, Yannick Champion, Nabil Njah
Abstract: The microstructure and mechanical properties were investigated in an industrial Al-Cu-Mg alloy processed by Equal Channel Angular Pressing ECAP and heating. The die used is formed by two channels intersecting at an angle 90°. Transmission Electron Microscopy (TEM) and orientation (ASTAR) imaging were used in addition to hardness measurements. After heating, a sub-micron grain size is retained. In addition, a further hardening is observed due to secondary precipitation. Differential Scanning Calorimetry (DSC) showed that the activation energy of θ’ precipitation is strongly lowered after ECAP.
Authors: Andreas K. Schaper, S.R. Zhao, A. Kutoglu
Authors: N. Lécaudé, J.C. Perron, N. Randrianantoandro, J.M. Grenèche
Authors: Mukhametkali Musagalievich Mataev, M.R. Abdraimova, Zh.D. Batyrbekova, A.M. Madiyarova
Abstract: By method of dynamic calorimetry, in the temperature range between 298,15 and 673 K, isobaric heat capacity of polycrystalline ferrites Bі2СаFe4O10, BіMgFe2O5.5, Bі2MgFe4O10 was experimentally studied. Mathematical processing of experimental data made it possible to derive polynomial equation of temperature dependence of ferrites heat capacity for respective temperature ranges, in dependencies C0p~f (T) of ferrite Bі2СаFe4O10 a jump was detected in heat capacity at 625K associated with phase transitions of type II. The values of the thermodynamic functions C0p(Т), H0(T) – Н0(298,15), C0(T), Fhh(Т) have been calculated. Standard values of thermodynamic functions were determined using the method of ion increments. The results obtained broaden thermodynamic data bank for complex inorganic crystalline compounds.
Authors: Dao Wu Yang, Yi Liu, Yan Yao, Hai Xia Tong
Abstract: The paper is focused on clarifying the influence of flue gas desulfurization (FGD) gypsum in replacing natural gypsum (NG) in the production of ordinary Portland cement (OPC). FGD gypsum was taken from Yi Yang power plant in Hunan, China. OPC clinker blends with 1–7 % of FGD gypsum to produce the binder of clinker/FGD gypsum. The properties of FGD gypsum was investigated via Chemical analysis, X-ray Diffraction (XRD), and differential thermal analysis (DTA)/thermogravimetric (TG) to evaluate the properties of binder. In present experiment, conduction calorimetry was applied to investigate the early hydration of binders. It was concluded that the blending of FGD gypsum reduced early hydration exothermic peak value of clinker and delayed the appearing time of exothermic peak at 30, and finally the early hydration of clinker was delayed effectively. This FGD gypsum is suitable as cement set retarders.
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