Petr Sulovský

The influence of the alite polymorphism on the strength of the Portland cement

The influence of the alite polymorphism on the strength of cement was monitored in a set of laboratory-prepared clinkers with equal quantitative phase composition and different ratio of modifications. The alite polymorphism in clinkers was influenced by the change of the MgO and SO3 side oxides in clinker, raw meal reactivity change, raw meal preheating, burning temperature or by the adding of crystallisation nuclei. The differences in the hydraulic properties of the M1 and M3 modifications were determined. In the case of all the hydration periods monitored, the strength of cements with the M1 modification was 10% higher than the strength of cements with the M3 modification.

Plasma-liquid technologies for treatment of archaelogical artifacts

Plasma-liquid technologies at atmospheric pressure provide a wide range of possibilities for applications. One of them, the treatment of archaeological artifacts, is presented in this paper. The effects of discharges between a metal electrode and a solution surface and/or an interaction of hollow cathode plasma jet, plasma pencil, with liquid on the corroded surface of bronze and glass artifacts were studied. It was compared with standard low pressure plasma techniques and with the effects of electrolysis. Original and treated objects were characterized by means of scanning electron microscope (SEM) with energy dispersive analyser used for the spot elemental analyses.

Plasma pencil — A new small scale source for atmospheric surface modifications

Plasma pencil is a device which can produce plasma jet at atmospheric pressure and low power (10–200 W) from DC to HF. The jet character of the plasma makes this device very efficient in aimed local (1 – 102 mm2) modifications of surfaces. Great variability in possible power sources allow to achieve a broad range of effects on materials. We have tested bipolar discharges with a metal object and a unipolar HF discharge to burn the glazing on ceramics. Both technologies could be prospective.

Interaction of Pipeline Materials with Molten Fluoride Salts

Molten fluoride salts are very promising carriers for the transport of large amounts of heat for example from a high temperature nuclear reactor to a plant which generates hydrogen by chemical processes or from a nuclear reactor to a heat exchanger being a part of the equipment needed to realize the Brayton cycle with a very high power efficiency. Therefore, in the framework of our project, experimental and theoretical investigations of the interactions of fluoride salts as heat carriers needed as high potential and structural materials for pipelines in order to transport heat at temperatures above 600◦C were started. Experimental investigations of Fe-based and Ni-based materials in molten fluoride salts at high temperatures and with different exposure times were performed. Two components salts (LiF-NaF and NaF-NaBF4) and three components salts (LiF-NaF-ZrF4 and LiF-NaF-RbF) were chosen in the experiments. The salt analysis was focussed on the content of metallic elements before and after the exposure of the samples to the salt melts. It was done by inductively coupled plasma-optical emission spectrometry (ICP-OES) and by titrimetric techniques. The thickness of the material zone affected by the salt melts, characterized by an enriched / reduced content of elements in comparison to the mean original content, and the material attacked zone, characterized by very tiny channels or chains of pores or pits formed preferably at grain boundaries, were the subject of the analysis performed by electron microscopy / microprobe techniques. Theoretical models for the transport of elements in the material samples exposed to salt melts using experimental data were also developed.

The Impact of Basic Minor Oxides on the Clinker Formation

In laboratory conditions, the effect of minor oxides – MgO and SO3 on formation of Portland cement clinker was observed. The research extended the current knowledge about the effect of these oxides on phase composition and structure of clinker and on alite polymorphism. Mainly means of optical and electron microscopy were used for the research.