Instytut Badawczy Dróg i Mostów, Warszawa
Coatings used to protect concrete surfaces in infrastructures should provide both a barrier against water penetration into construction, and to provide for ”breathing” of the concrete. This ”breathing” is characterized by water vapor transmission rate. Requirements for the values are specified in PN-EN ISO 7783-2:2012 and PN-EN 1504. Vapor transmission is particularly important, because the choice of protection system is often not carefully controlled causing blistering and delamination. The effect of the thickness of coatings based on various binders used for surface protection of concrete structures on their vapor permeability is disscused.
Keywords: protective coatings, concrete surfaces, thickness, vapor permeability, water-vapor transmission rate V, water-vapor diffusion-equivalent air layer thickness sd
Vol. 59, nr 2
Faculty of Production Engineering and Materials Technology, Department of Chemistry,
Częstochowa University of Technology, Al. Armii Krajowej 19, 42-200 Częstochowa, Poland /
Particles of hydrogen storage, LaNi4.5Co0.5 powdered material have been encapsulated with thin (about 40 nm) Fe-Cr-Ni layers using magnetron sputtering method. The acid resistant, 1.4301 (EN 10088) stainless steel has been applied as a target. The effect of powder encapsulation on galvanostatic charge/discharge characteristics (hydride capacity, exchange current density of the H2O/H2 system, susceptibility to oxidation) for the modified hydride electrodes has been evaluated. The plots of discharge curves testify to limitation of active material tendency to working surface development. The material modified reveals comparatively high discharge capacities which should be attributed to inhibition of oxidation processes of active material by the surface layers formed. The powder sputtering does not worsen the kinetics of charge/discharge processes for modified electrode.
Keywords: LaNi5 type hydride material, magnetron sputtering, galvanostatic hydrogenation, charge/discharge
Vol. 59, nr 2
Silesian University of Technology, Institute of Materials Science, Katowice, Poland
Institute of Non Ferrous Metals, Department of Powders and Composites Materials, Gliwice, Poland
Results of investigations characterizing oxidation resistance of pure Mo and TZM alloy (with addition of Ti and Zr) after siliconizing process in activated pack were showed in this article. The oxidation test was made in laboratory air at temperature 1200°C in quasi isothermal conditions. The specimens to microstructural investigations were taken after 25, 50 and 100 hours of exposure. The durability of silicide’s coatings on Mo and TZM alloy is related strongly to their quality and especially to: presents of microracks as well as ability to self-healing process. In the case of MoSi2 type of coatings the presents of deeply penetrating microcracks suddenly increased the failure process of substrate materials, and the self-healing effect was not observed. In the areas of coatings free from discontinuities the durability of silicide layer was very good in oxidation test condition.
Keywords: silicide coatings, molybdenum, TZM alloy, oxidation resistance
Vol. 59, nr 2
CORROSION PROTECTION IN PRACTICE
University of Žilina, Department of Structures and Bridges
Corrosion protection concentrates on prevention of corrosion formation and reducing losses caused by corrosion. The degradation of metallic materials (steel reinforcement) is mainly the result of electrochemical reactions. When designing corrosion protection (anodic, cathodic) it is necessary to take into account the likelihood, range and possible effects of action of corrosion in particular conditions, as well as available forms of protection against corrosion, effectiveness of anticorrosion methods and their cost (initial, operational, etc.). The paper deals with implementation of cathodic protection of tanks of the sewage treatment plant in Čadca.
Keywords: corrosion, reinforcement, concrete, cathodic protection, sewage treatment plant
Vol. 59, nr 2