Technologie hmot a dílců AdMaS
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- ItemImpact of Aggressive Media on the Properties of Polymeric Coatings with Solidification Products as Fillers(MDPI, 2019-11-26) Hodul, Jakub; Mészárosová, Lenka; Žlebek, Tomáš; Drochytka, Rostislav; Dufek, ZdeněkDealing with waste materials, particularly hazardous waste, is a serious problem. Disposal areas keep growing, and the costs incurred are high. Disposing of such waste reduces negative environmental impacts and offers considerable financial savings. This paper focuses on the possibilities of incorporating pollutants found in hazardous wastes as fillers in coatings based on polymers (epoxide and polyurethane). These coatings are intended mainly for concrete and metal bases and offer secondary protection against adverse weather conditions. Important physical and mechanical properties of the newly developed materials were determined; they include surface hardness, impact resistance, tensile properties, and chemical resistance. These properties were also compared to those of the reference filler. At the same time, the influence of aggressive media on the properties of these materials was observed, in particular on flexural characteristics. The microstructures of the developed coatings were tested using a high-resolution optical microscope, before and after exposure to the chemicals. The positive effect of using progressive fillers, such as solidified hazardous waste (a solidification product (SF)), was witnessed by their constructive contribution to the materials’ physical and mechanical properties. The use of solidification products is unambiguously advantageous from technical, ecological, and economical stand points (utilization of hazardous waste as a progressive filler instead of landfilling, improvement of tensile properties, reduction in the price of coating system, and incorporation of the pollutants into the polymer matrix).
- ItemDesign of tailored biodegradable implants: The effect of voltageon electrodeposited calcium phosphate Coatings on puremagnesium(The American Ceramic Society, 2019-01-01) Horynová, Miroslava; Remešová, Michaela; Klakurková, Lenka; Dvořák, Karel; Ročňáková, Ivana; Yan, Shaokun; Čelko, Ladislav; Song, Guang-LingMagnesium, as a biodegradable metal, offers great potential for use as a tempo-rary implant material, which dissolves in the course of bone tissue healing. It cansufficiently support the bone and promote the bone healing process. However, thecorrosion resistance of magnesium implants must be enhanced before its applica-tion in clinical practice. A promising approach of enhancing the corrosion resis-tance is deposition of bioactive coating, which can reduce the corrosion rate ofthe implants and promote bone healing. Therefore, a welldesigned substratecoat-ing system allowing a good control of the degradation behavior is highly desir -able for tailored implants for specific groups of patients with particular needs. Inthis con tribution, the influence of coating formation conditions on the charact eris-tics of potentiostatically elect rodeposited CaP coatings on magnesium substratewas evaluated. Results showed that potential variation led to formation of coat-ings with the same chemical composition, but very different morphologies.Parameters that mostly influence the coating performance, such as the thickness,uniformity, deposits size, and orientation, varied from produced coating to coat-ing. These characteristics of CaP coatings on magnesium were controlled by coat-ing formation potential, and it was demonstrated that the electrodeposition couldbe a promising coating technique for production of tailored magnesium CaPimplants.
- ItemEffect of Imposed Shear Strain on Steel Ring Surfaces during Milling in HighSpeed Disintegrator(MDPI, 2020-05-13) Dvořák, Karel; Macháčková, Adéla; Ravaszová, Simona; Gazdič, DominikThis contribution characterizes the performance of a DESI 11 highspeed disintegrator working on the principle of a pin mill with two opposite counterrotating rotors. As the ground material, batches of Portland cement featuring 6–7 Mohs scale hardness and containing relatively hard and abrasive compounds with the specific surface areas ranging from 200 to 500 m2/kg, with the step of 50 m2/kg, were used. The character of the ground particles was assessed via scanning electron microscopy and measurement of the absolute/relative increase in their specific surface areas. Detailed characterization of the rotors was performed via recording the thermal imprints, evaluating their wear by 3D optical microscopy, and measuring rotor weight loss after the grinding of constant amounts of cement. The results showed that coarse particles are ground by impacting the front faces of the pins, while finer particles are primarily milled via mutual collisions. Therefore, the coarse particles cause higher abrasion and wear on the rotor pins; after the milling of 20 kg of the 200 m2/kg cement sample, the wear of the rotor reached up to 5% of its original mass and the pins were severely damaged.
- ItemStudy of Possibilities of Using Special Types of Building and Demolition Waste in Civil Engineering(Budapest University of Technology and Economics, 2020-01-15) Drochytka, Rostislav; Dufek, Zdeněk; Michalčíková, Magdaléna; Hodul, JakubConstruction and demolition waste makes up a substantial part of all waste produced in Europe. Its impact on the environment may be relatively small, but it exists in large amounts and holds many options of re-use. This is why it remains a frequently discussed topic of European policy. As part of circular economy, the European Commission has already proposed new goals and strategies for existing types of waste. However, they are not entirely clear on the usage of new kinds of building and demolition waste, as they are yet to be specified by existing legislation. This paper discusses new kinds of building and demolition waste and the basic principles (new technology) of their use. The possibilities of utilizing new kinds of waste are based on a multicriteria optimization calculation, specifying each material and proposing ways of its further use. Recent findings can expand the choice of new uses of construction and demolition waste and reduce their impact on the environment (less waste, better properties and more effective processing, reducing transportation needs, maximizing re-use and recycling).
- ItemDevelopment of Crystallinity of Triclinic Polymorph of Tricalcium Silicate(MDPI, 2020-08-24) Ravaszová, Simona; Dvořák, KarelTricalcium silicate phase is one of the main components of modern Portland cements. One of the major industrial challenges in the field of cement production is mapping the influence of individual clinker minerals and their polymorphs on the properties of industrially produced clinkers. The primary goal of this work is to improve the fundamental knowledge of understanding the process of alite formation and development from a crystallographic point of view. This study focuses on the observation of the crystallization process of triclinic alite during the firing process, which to date has not been thoroughly described. The effects of a wide range of temperatures and sintering periods on crystallinity were assessed on samples fired in platinum crucibles in a laboratory furnace. X-ray analysis—together with calculation of crystallinity using Scherrer’s equation—was used for observing the crystallite size changes of T1 alite polymorph. According to the acquired results, among the most technologically and economically advantageous regimes of production of a high-quality triclinic alite is the temperature of 1450 °C and sintering time of two hours. The most significant changes in the crystallite size occurred within the first hour of sintering for the whole investigated temperature range.