Materials Science Forum Vol. 818

Abstract: The peculiarities of the accumulation of structural and mechanical defects on the surface of the D16chT aluminum alloy under significant plastic strains are analyzed. The peculiarities of the surface strain hardening are found, and the geometrical parameters of the relief formations are described. The relationship between multiple cracking and specimen deformation is established. It is proved that the deformation relief parameters can be used to assess damage of the D16chT alloy under static deformation.

Abstract: The preservation ability of coatings applied to the materials of steel products, steel structures, etc., for short-term corrosion protection is a very delicate and modern theme. In cooperation with the project Pre-seed, we can pay closer attention to activities involved with this topic. The project Pre-seed at the Technical University of Ostrava, which is part of the Operational Programme of Research and Development for Innovation, attempts to support the preparation of the commercialization of promising technologies and inventions with high application potential that were developed at the Technical University of Ostrava. This paper focuses on the short-term corrosion protection of steel products, steel structures, and engineering products using thin nanocoatings. This experimental work is primarily concerned with the production and development of samples that demonstrate the innovativeness and functionality of the issue. Furthermore, the project addresses important factors affecting the quality and durability of the coating system. The results of the experimental part show us some very interesting outputs that need to be further studied and developed.

Abstract: Protective coatings on the basis of Zn-Mg are still more a more used in present engineering industry. However their wider using (e.g. in the automotive industry) is still limited by unsufficient and pure knowledge about their behavior in dependence on deformation. Thus this paper is focused on testing tribological properties and their change in dependence on size of deformation. That is why there was used tribological strip drawing test where samples were firstly deformed on different values (15% and 30%). Subsequently were these strips drawn between hardened and non-hardened jaws and there were evaluated different forces necessary to draw a strip and friction coefficient was calculated. Main results (mainly course of friction coefficient on pressure and deformation) were shown as graphs and tables.

Abstract: The possibility of formation of coatings based on co-polymers 2-hydroxyethylmethacrylate with polyvinylpirrolidone on different nature surfaces is determined. It is investigated, that adsorption of liquid compositions components to surface-base affects the formation of coating from such compositions. The composite metal-filled coatings are obtained on the basis of synthesized polymers. Such coatings are characterized by variable conductivity dependently on moisture content, pH and low-molecular substances availability.

Abstract: The aim of the paper was to discover the influence of modifying HDPE with selected agents that is a blowing agent, in the course of the extrusion process, inclusive of determination how the modification affects selected physical properties and properties of the surface of HDPE extrusion product. Endothermic chemical blowing agents in the amount of 0.6 % by mass were used in the research. The article presents selected results of examination of melt flow rate (MFR) and microscopic structure.

Abstract: The determination of the effect of composition formula and hardening conditions on technological characteristics of developed thermostable enamels on the basis of phenol-formaldehyde resins modified by epoxy resin and polyvinylpyrrolidone (PVP) was the task of this work. The mechanism of resins modification and hardening has been determined. The developed modified composition is characterized by high index of thixotropy in contrast to phenol-formaldehyde resin (PFR) containing urotropine. It was determined that novolac phenol-formaldehyde resin modification by PVP and ED-20 results in a significant improvement of thixotropic characteristics and enamel technological effectiveness and in physico-mechanical properties and thermostability improvement as well.

Abstract: Optimizing the mechanical properties of composites is very important for light low energy constructions. Unidirectional prepreg (UD prepreg) is an intermediate product synthesizing a unidirectional layer of carbon fibres with a matrix. This can be used in the production of continuous fibres of reinforced composites. The individual layers can be stacked on top of each other to precisely orientate the layers and attain the maximum properties in a given direction. The resulting composite is ultra thin with the highest possible fraction of fibres. Prepreg composites are very high quality and have very good mechanical properties. They can be applied in sectors where the requirements for mechanical resistance are very high. This paper presents an experimental and numerical analysis of the surface of a composite and the changes that may occur to it under the influence of loading. The Ball Drop Test (ASTM D6024-07 / DIN 52306) was used as a stress test. Test samples scanned by image analysis showed that the surface properties of the UD prepreg were not disrupted, while scanning with AXIO IMAGER M2 showed apparent surface disruptions. From the numerical simulations it was determined that a directional orientation of the fibres of +45°/0°/-45° significantly affects their elastic properties.

Abstract: Contribution deals with evaluation of the electrodeposition process of octacalcium phosphate layer on the surface of Elektron 21 magnesium alloy. The octacalcium phosphate coating (OCP) was electrochemically deposited in a solution containing 0.167 M CaCl₂ and 0.1 M NH₄H₂PO₄. The formation of calcium phosphate was divided into several stages and described using light microscopy. The influence of octacalcium phosphate layer on the electrochemical characteristics of Elektron 21 magnesium alloy was evaluated by potentiodynamic measurements in 0.1 M NaCl solution at a temperature 22 ± 1°C. Evaluation of calcium phosphating process realized on the alloy surface after grinding was investigated by electrochemical tests supported by photodocumentation using stereomicroscope.

Abstract: The tinplate possesses several important advantages, such as drawability, good solderability and corrosion resistance. Plastic and strength properties are better because recrystallization annealing is including in the sheet production process. Some products may be either continuously annealed (CA) or batch annealed (BA). In the contribution we deal with relation between magnitude of plastic deformation and of its influence to corrosion resistance of tinplates.

Abstract: The paper presents the evaluation of corrosion resistance of aluminium alloy AlSi1MgMn. This alloy is used above all in any atmospheric conditions. The corrosion resistance of the alloy was evaluated by determining the open circuit potential (OCP) in solution SARS (this solution simulates the industrial atmosphere) after the 10 months of exposure time. The surface of aluminum alloys were analyzed by using energy dispersive X-ray analysis after the exposure time. The basic of corrosion characteristics (corrosion potential E_corr, corrosion rate i_corr and polarization resistance R_p) were determined by potenciodynamic measurements according to Tafel’s and Stern’s methods.