STUDING OF ROLL STEEL STRUCTURE FORMATION PROCESS

Roll steel crystallization process, and formation process of it's microstructure during cooling are considered in this article. Presented results are received by conducting of laboratory experiments, metallographic researches of roll steel. Short review of science literature is carried out, data about alloys applied in roll production is showed in first part of the article. Moreover, problems in roll manufacture, with which industry have faced, as well arising due this science obligatoriness for making researches, are considered. Based on performed analysis, the researches' target is formulated. Methodology and equipment used during researches are short considered in second part of the article. Besides, influence of cooling speed on roll steel parameters: actual grain size, carbide phase quantity, and temperature intervals of its formation are reviewed. Quantity characteristics of roll steel microstructure have determined. Data received due researches in laboratory conditions are presented graphical. Conclusions based on obtained results, as well as recommendations for further researches are given in final part of the article.

Morphology on Reaction Mechanism Dependency for Twin Polymerization

An in-depth knowledge of the structure formation process and the resulting dependency of the morphology on the reaction mechanism is a key requirement in order to design application-oriented materials. For twin polymerization, the basic idea of the reaction process is established, and important structural properties of the final nanoporous hybrid materials are known. However, the effects of changing the reaction mechanism parameters on the final morphology is still an open issue. In this work, the dependence of the morphology on the reaction mechanism is investigated based on a previously introduced lattice-based Monte Carlo method, the reactive bond fluctuation model. We analyze the effects of the model parameters, such as movability, attraction, or reaction probabilities on structural properties, like the specific surface area, the radial distribution function, the local porosity distribution, or the total fraction of percolating elements. From these examinations, we can identify key factors to adapt structural properties to fulfill desired requirements for possible applications. Hereby, we point out which implications theses parameter changes have on the underlying chemical structure.

STRUCTURE FORMATION PROCESS OF HYDRATED PORTLAND CEMENT COMPOSITIONS: NANOSCALE LEVEL CONTROL

Durability of cement-like construction materials, as well as durability of cement stone, depends on their humidity resistance, frost resistance, corrosion resistance. All of these properties depend not only on the composition of the original clinker, but also on structural organization at micro-and nanoscale level of hydrated portland cement compositions. In this research the authors used the method of small-angle neutron scattering to define structural parameters of hydrated portland cement compositions on nanoscale level, distribution of calcium hydrate silicate nanoparticles in size, medium nanoparticles radius, fractal dimension. It is shown, that introduction of modifying nanoadditives into portland cement compositions affects structural parameters of a cement stone. The following nanoadditives were used: of artificial (alpha aluminium oxide, gamma aluminum oxide) and of anthropogenic (carbonate and alumo-alkaline sludges) origin, as well as integrated nanoadditives containing surfactants. The change in structural parameters of portland cement compositions with nanoadditives in the process of hydration is investigated. It is shown that use of nanoadditives allows to control the process of forming the structure of hydrated portland cement composition on the nanoscale level, directly affect the values of structural parameters and, as a result, modify properties of cement stone.