Actual number: 4/2020

ISSN 1339-5017 (Online)

Archive:


No. 2

FRACTURE SURFACE OBSERVATION OF ARMOX 500T IN DEPENDENCE ON TEMPERATURE

Author: Norbert Adamec, Vladimír Bella, Mariana Kuffová

Abstract: Fracture surface gives us the information about material properties. Fracture can be ductile or brittle in dependence on consumed energy. As far as the fracture surface is concerned, we distinguish the plastic and brittle fracture. The aim of the article is to show the fracture surface of steel ARMOX 500T after the impact bend test in dependence on temperature.

Keywords: Toughness, hardness, chemical composition, temperature, fracture surface

Vol. 6, 2012, No. 2, p. 02-05

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SECONDARY PROCESSING OF UHSLA ARMOX 500 STEEL WITH HEAT BASED TECHNOLOGIES

Author: Igor Barényi

Abstract: ARMOX steels are armored steels used for protect devices and facilities against blasts and explosions. Due to this purpose the ARMOX 500 steel has excellent mechanical properties as are high hardness, tensile strength and good toughness. These properties result from specific production process finished with rolling ant then quenching and tempering. The producer of ARMOX steels recommend their secondary processing (cutting, welding, shaping) at temperatures lower than 200°C due to over tempering and degradation of mechanical properties in heat affected areas. The paper describes the mechanism and reason of this degradation including the simulation of cooling process with ARMOX 500 steel.

Keywords: UHSLA steel, ARMOX, secondary processing, mechanical properties, heat treatment

Vol. 6, 2012, No. 2, p. 06-09

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COMPUTATIONAL PROCESSING OF EXPERIMENTAL DATA FROM LASER SCANNING CONFOCAL MICROSCOPY

Author: Tomáš Bezák, Martin Kusý, Michal Kopček, Michal Eliáš

Abstract: The contribution introduces basics of laser scanning confocal microscopy and its applications as metrological and topographical tool. It shows evaluation of typical surface parameters implemented in commercial computer program installed with microscope such dimensional measurements, roughness measurement and volume of material/void determination using bearing area ratio. Despite of rather broad spectra of evaluated parameters user tailored applications could be treated only with difficulties. First attempt to visualize measured data with third-party application is introduced with outlook to implement semiautomatic or automatic approaches to determine topographical parameters at complex surface patterns such as spherical spurs. Visualisation in grid-like mode using Matlab was performed on experimentally collected data. These were exported from ZEN2009 in Cartesian coordinates. Further aim is to implement semiautomatic or automatic approaches to evaluation of roughness or 3D dimensional objects with implementation of ISO standards where applicable.

Keywords: microscopy, laser scanning confocal microscopy, topography, profile roughness, topographic roughness

Vol. 6, 2012, No. 2, p. 10-16

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THE EFFECT OF COLD FORMING ON THE MECHANICAL AND STRUCTURAL PROPERTIS OF SELECTED STEELS

Author: František Bryndzia, Martin Šimák, Ondrej Híreš, Mária Ličková, Daniela Žabecká

Abstract: Contribution shows the possibility the secondary reinforcement of the selected types of steel, by the influence the influence of strain hardening. The experimental samples were exposed to intense light temperature annealing (200 ° C, 300 ° C, 500 ° C) for 20 minutes, after 20 minutes followed cold forming with a reduction 10 % of thickness. We observed the change of strength, ductility and the microstructure of forming material.

Keywords: strain hardening, forming, low-temperature annealing, tensile strength, reduction

Vol. 6, 2012, No. 2, p. 17-20

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MODELLING OF THE UGV'S TERRAIN STABILITY

Author: Viktor Ferencey, Juraj Madarás, Martin Bugár, Elza Kočíková

Abstract: This paper describes a mathematical modelling of stability of a Unmanned Ground Vehicle (UGV) that accounts for the tendency to slide, tipover, or lose contact with the ground considering both static equilibrium and dynamic effects. The mathematical modeling of stability is computed by solving for the range of acceptable angles that satisfy a set of dynamic constraints.

Keywords: UGV, stability, terrain, model, simulation, driveability

Vol. 6, 2012, No. 2, p. 21-26

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APPLICATION OF A SELECTED TRANSFORMED ENGINE FROM REDUNDANT SPECIAL EQUIPMENT FOR CRISIS MANAGEMENT NEEDS

Author: Marián Hocko, Peter Lipták

Abstract: The article performed an analysis of possibilities of the conversion of military helicopter turbo shaft engines for energetic use.

The possibilities of the transformation of the turbo shaft engine on the energetic unit are indicated on the example of the helicopter turbo shaft engine GTD-350, which was used in the military version of the Mi-2 helicopters. The article is the result of detailed studies, which creates the basic prerequisites for solving the problems in industrial conditions.

Keywords: special technique, transformed aero turbo shaft engine, power unit, crisis management.

Vol. 6, 2012, No. 2, p. 27-33

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LAYERED SILICATES AND THEIR INTRACTIONS WITH TOXIC ORGANIC COMPOUNDS

Author: Eugen Jóna, Martina Loduhová, Simona Lendvayová, Darina Ondrušová, Mariana Pajtášová, Pavol Lizák

Abstract: The influence of organic compounds: ethylenediamine (EDA), trimethylethylenediamine (TrMeEDA) and tetramethylethylenediamine (TeMe EDA) on the type of interactions with Ni- exchanged montmorillonite were studied. The results of thermal, diffraction and spectral analysis shown that studied diamines are intercalated into the interlayer space of montmorillonite. It was found that EDA is coordinated to Ni2+ and alkyldiamines are in protonated forms. The effect of different steric properties of individual diamines is evident.

Keywords: Ni - exchanged montmorillonite, interactions with ethylenediamine and its methylderivatives

Vol. 6, 2012, No. 2, p. 34-37

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PREPARATION AND STUDY OF MECHANICAL PROPERTIES OF POLYLACTIC ACID/STARCH OLEATES BLENDS

Author: Jarmila Kebísková, Iva Sroková, Vlasta Sasinková, Mária Chromčíková

Abstract: In presented work, the blends composed from pure polylactic acid (PLA) and starch oleates were examined. Starch oleates (SO) with different degree of substitution (DS) were prepared by esterification of native starch and oleoyl chloride in heterogeneous conditions (pyridine). These prepared starch esters were used in the function of additives for preparation of blends with PLA. The PLA/starch oleates blends (9:1) have been prepared and evaluated by using attenuated total reflectance (ATR) spectroscopy technique. Subsequently, their mechanical properties, such as storage modulus (E'), loss modulus (E'') and tan D were studied as a function of temperature by dynamic mechanical thermal analysis (DMTA). These blends containing 10 wt. % SO show satisfactory mechanical properties in comparison to pure PLA.

Keywords: starch oleates, PLA, blends, mechanical properties

Vol. 6, 2012, No. 2, p. 38-42

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ANTIOXIDATIVE AND SOLUTION PROPERTIES OF NEW CINNAMATE ESTERS OF CARBOXYMETHYLCELLULOSE

Author: Vladimíra Krmelová, Katarína Kostelanská, Iva Sroková, Lyda Rychlá

Abstract: New cinnamate esters of O - carboxymethylcellulose (CMC) with low degree of substitution (DS) were prepared by esterification of cinnamic acid. The chemical modification was performed in different reaction media N,N-dimethylformamide (DMF)/4-toluenesulfonic acid (4-TSA) and H2O/DMF with 4-dimethylaminopyridine (DMAP) as catalyst and N, N-dicyclohexylcarbodiimide (DCCI) as activator of cinnamic acid (CA), at various reaction conditions. The obtained derivatives were characterized by FT-IR and UV spectroscopy. Surface-active properties and antioxidative activity of the cinnamate esters of CMC was evaluated. In spite of the low surface tension-lowering effect, prepared derivatives exhibited excellent emulsifying efficiency. The cinnamate CMC derivatives showed low antioxidant activity.

Keywords: carboxymethylcellulose, cinnamic acid, surface-active properties, antioxidative properties.

Vol. 6, 2012, No. 2, p. 43-46

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INFLUENCE OF VARIOUS TONES OF COLORS ON MEASURING POROSITY OF KNITTED FABRICS PRINTED BY SUBLIMATION

Author: Jela Legerská, Pavol Lizák, Matej Drobný, Silvia Uríčová

Abstract: The pores can be characterized as small air spaces in structure of a knitted fabric. By comparing of area of pores with the area of knitted fabrics, we are able to determine the index of porosity. The porosity of the knitted fabric has the decisive influence on the properties and usage of the knitted fabric. Therefore, it is necessary to express it theoretically and measure it experimental. The aim of measurement was to evaluate the influence of the color tone printing for measuring porosity. The given measurements of the porosity were done with utilization of the image analysis compounded from Nikon microscope, CCD camera and NIS Elements software. The porosity of knitted fabrics was measured on difference color areas. The result of these experimental measurements was expression of dependence between the porosity of the knitted fabrics and the number of the pores at the knitted fabric. The attention was also paid to shapes as well as size of pores in the given knitted fabric.

Keywords: porosity, color tone, knitted fabric, sublimation printing, image analysis

Vol. 6, 2012, No. 2, p. 47-51

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ELECTRICAL PROPERTIES OF THE TEXTILE FABRICS

Author: Jela Legerská, Pavol Lizák, Matej Drobný, Jaroslav Ligas

Abstract: The frequent demand placed recently for clothing, furnishing and technical textiles made of synthetic polymers is evaluation the electrical properties in accordance with application intentions. These textile fabrics are evaluated by methods of measuring the surface resistance and the electrical resistance. Given methods have sufficient ability to express conducting and transferring of the electrostatic charge on their surface. There are evaluations of electrical and thermal resistance are presented in publication. The results obtained from two types of nonconductive woven fabrics from different material composition were discussed in this paper as well. The aim was to compare non-homogeneous textile materials and evaluated the influence of electrical properties on thermal insulation properties.

Keywords: Specific electrical conductivity, specific electrical resistance, resistivity, thermal resistance, thermal conductivity

Vol. 6, 2012, No. 2, p. 52-57

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REAL CASES OF OCCURRENCE OF UNTYPICAL BRITTLE RUPTURE OF STEEL COMPONENTS DUE TO BENDING STRESS

Author: Ján Mičic, Ján Bezecný, Annamária Petráňová

Abstract: Companies carry out wide range of activities, whose quality, range and form significantly affect its performance, success on the market and overall competitiveness. Marketing activities are part of company management process and affect the philosophy of the development of the company, its overall position on the market and competitiveness. Marketing contribution in the company depends on economic and technical conditions as well as the size of the company. Content of marketing is different in small and medium enterprises and large companies. In terms of increasing competitiveness, small and medium enterprises create development strategies, which include strategic marketing.

Keywords: embrittlement of steels, thin-walled components, retained austenite, martensite

Vol. 6, 2012, No. 2, p. 58-62

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SUBSTITUTION OF CARBON BLACK BY ZEOLITE NANOFILLERS IN THE RUBBER COMPOUNDS

Author: Darina Ondrušová, Mária Kopcová, Mariana Pajtášová, Michaela Ďurčeková, Martina Čechová, Zuzana Jankurová, Eugen Jóna

Abstract: The present work deals with the preparation and study of environmentally friendly modified polymer compounds with the replacement of carbon black by nanofillers on the base of zeolite. Zeolites form a group of aluminosilicate nanoporous materials with wide possibilities for applications, that are environmentally friendly. Zeolites can be used in the role of fillers in the polymer materials too. The prepared modified polymer compounds were characterized by the methods of thermal analysis and their vulcanization performance and physical-mechanical properties of vulcanizates were measured. The found values were compared with the values of commercially used polymer materials with the original composition.

Keywords: Zeolite nanofiller, carbon black, rubber compound, thermal analysis, physico-mechanical properties

Vol. 6, 2012, No. 2, p. 63-66

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PREDICTIVE TOOL FOR AIRCRAFT PLATFORMS

Author: Ferdinand Tesař, Jiří Stodola

Abstract: Article describes approach used for development of new analytical methods and procedures for interpretation of complex data gathering on board and/or from ground analysis of combat air platforms for their prediction of service status ability.

Keywords: diagnostic, aircraft, data mining.

Vol. 6, 2012, No. 2, p. 67-73

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EFFECT OF POLYETHYLENE OXIDE ON BASIC PROPERTIES OF BENTONITE FOUNDRY SAND MIXTURES

Author: Harold Mäsiar, Jozef Kasala, Peter Lipták, Zuzana Lacková

Abstract: Very small quantities of polyethylene oxide with molecular weight of 600 000 (PEO) exhibit a non-additive effect of increased permeability that is higher in higher compaction energies (19.62 J). Increased permeability has been proven at such small PEO quantities as 0.0365 %-wt., 0.073 %-wt., and 0.1 %-wt.. That effect is limited for PEO higher than 0.1 %-wt. it is that PEO effect will find application in metal casting at lower melting temperatures.

Keywords: Bentonite, Polyethylene Oxide, Foundry mixtures, Permeability, Bondability, Surface Hardness

Vol. 6, 2012, No. 2, p. 74-79

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