Authors:O. F. Shlensky, L. N. Aksenov, Yu. V. Zelenev, and E. M. Eremenco
The method of DTA and design of two thermoanalytical cells are suggested for high-rate heating of samples at speeds up to 103 °C s−1 and more. Method allows to determine the limiting temperature of attainable superheat during thermolysis processes of melting substances. Some testing results are given.
A highly simplified method for calculating heat of phase transitions from DTA data is presented. Two DTA curves are needed to calculate the heat of transition and the specific heat of the sample: one is for the original sample and one is for a sample prepared by mixing the original sample with some unreactive diluent the specific heat of which is known. The data of the DTA curves used in the calculations are the peak area, the rate of heating and the deviation of the DTA curve from the base line.
The hydration kinetics of C3S pastes can be easily evaluated by DTA using the most intense and reversible transition of C3S. Some modifications are proposed to Ramachandran's method concerning the measurement of this effect, the weight of the sample used for each experiment and the heating rate. The results of the hydration degree versus times of C3S agree reasonably with those reported by Ramachandran, while still better agreement is observed with those of Locher who used X-ray quantitative analysis.
Authors:V. Vasilyev, E. Kalevich, V. Radchenko, E. Shimbarev, V. Egunov, A. Izmalkov, and V. Vasilyev
Thermal decomposition of oxalate and nitrate hydrates of transplutonium elements has been studied by differential thermal and X-ray analysis, under heating in helium and oxygen. The formation heats of anhydrous crystalline Am(III) and Cm(III) nitrates were estimated from DTA data. Data of the self-decomposition of244Cm(III) salts under the influence of inherent -radiation were obtained.