Authors:S. Marinković, A. Kostić-Pulek, S. Durić, V. Logar, and M. Logar
Selenite was boiled in KCl solutions of different concentrations at the respective boiling temperatures and atmospheric pressure. The products were subjected to X-ray diffraction analysis, qualitative infrared analysis, differential thermal analysis and microscopic examination. The product obtained in 1.0 M KCl solution was the -form of calcium sulphate hemihydrate (-CaSO4·0.5H2O). In more concentrated KCl solution (1.5, 2.0, 2.5, 3.0, 3.5 or 4.0 M), the -form of calcium sulphate hemihydrate (-CaSO4·0.5H2O) was formed, and a reaction took place between KCl and CaSO4, which gave a double salt: potassium pentacalcium sulphate monohydrate (K2SO4·5CaSO4·H2O).
A review is given of various metallurgical problems treated in the author's laboratory, for which quantitative calorimetry gave very valuable information. Measurements of thermodynamic data for phase diagram calculations, vacancies in ordered alloys, annealing of steels, and the recovery and crystallization of amorphous alloys are successively examined.
The crystallization behaviour of amorphous melt spun Fe82−x−yCr18ZrxBy (x=0–8, y=10–20) ribbons have been investigated using differential scanning calorimetry. The crystallization temperature and
crystallization behaviour change with varzing Zr and B content.
The microstructural development during annealing of amorphous Fe64Cr18Zr8B10 has been investigated by a combination of transmission electron microscopy and energy dispersive X-ray microanalysis. Isothermal
annealing for 2 h at temperatures in the range 600–1000°C produces a variety of different microstructures depending on the
annealing temperature. At 600°C, the amorphous alloy partially crystallizes to a form a microstructure consisting of 9 nm
sized bee ferrite grains embedded in an amorphous matrix. At temperatures in the range 700–900°C, the alloy microstructure
transforms into a mixture of bee ferrite, faulted fcc MB12 boride particles and tetragonal M3B boride particles. At 1000°C, the faulted fcc MB12 boride particles are replaced by orthorhombic M4B boride particles.
The influence of radioactive krypton85Kr on the surface properties of poly(3-pentylthiophene) has been studied. Irradiation by gaseous85Kr leads to structural polymeric chain changes, which induce after iodine doping the formation of charge-transfer complexes with iodine as well as with gaseous sulfur dioxide manifesting itself by the increased electric conductivity. The presence of ammonia brings about reaction with iodine bound in the complex with a conducting polymer.
Both oxidation and methoxymethylation of the surfaces of a series of MDI (methylene diphenyl isocyanate) and TDI (toluene
diisocyanate) polyether and polyester soft segment 1–4 butanediol polyurethanes result in increased thermal stability as measured
by TG. Explosive loss of mass above the hard segment melting temperature suggests that the diffusion of the dissociated diisocyanate
moiety is hindered at lower temperatures. Thus suppression of the depolycondensation reaction by chemical blockage of the
surface may result in a material with an increased service life at use temperatures as thermal stability of a polyurethane
may depend upon the low diffusivity of its diisocyanate comonomer. The effect of vacuum, oxygen and water vapor on the kinetics
of mass-loss of several of the polyurethanes is presented.
Authors:Š. Jakabský, M. Lovás, A. Mockovčiaková, and S. Hredzák
The paper is devoted to the utilization of ferrofluid as a separating medium and modifying agent affecting the magnetic properties of solid and liquid materials. The separation tests in a MHS separator have been carried out under laboratory condition. The selectivity of ferrofluid's adsorption to the surface of some materials can be used for enhancing the magnetic susceptibility and influencing the efficiency of separation process. The enhancement of magnetic susceptibility of oil products up to a level sufficient for their magnetic extraction from water is possible by admixing of a definite amount of kerosene-based ferrofluid, which is non-miscible with water. The results point to the fact that the MHS method is suitable for the separation of non-magnetic materials according to their density and the modification of magnetic properties of materials by ferrofluid enhancing their magnetic separability.