Actual number: 4/2021
ISSN 1339-5017 (Online)
Archive:
No. 4
NANOINDENTATION STUDY OF CHROME LAYER
Author: Maroš Eckert, Michal Krbaťa
Abstract: The article focuses on the analysis of chromium layers applied in various companies on the base material in the form of a tube of AISI 304 material. The measurement of the thickness of the chromium layer was performed by optical microscopy on samples formed by cross section. The quality of the chromium layer was evaluated using two different methods of measuring hardness. One was the clas-sical method of measuring microhardness (Hv0.1) from the surface part of chromium. The second method was nanoindentation analysis, in which the nano-hardness was measured along the thickness of the chromium layer. The results show that the surface hardness has increased more than 3-fold by using a chromium layer. It has also been shown that a layer with greater thickness does not show the greatest microhardness. From the nanoinden-tation results, it was confirmed that the layer with the highest surface hardness also shows the highest nanoindentation hardness after the layer thickness, and this hardness decreases in the direction away from the surface of the base material in all layers.
Keywords: Chrome layer, Nanoindentation, Microhardness, Nanohardness
Vol. 15, 2021, No. 4, p. 1-6
Download PDFMICROSTRUCTURAL ANALYSIS OF HETEROGENOUS FRICTION WELD STEEL 23B2 WITH COPPER
Author: Matúš Gavalec, Igor Barényi
Abstract: Friction welding is effective method of joining materials, widely used not only on field of join-ing two different types of materials. This arti-cle is focused on friction welding of boron steel 23B2 with DHP copper. Welded workpieces were cylindrical with 10 mm diameter. Micro-structural analysis was used as a control method of friction welds.
Keywords: Boron steel, Copper, Friction welding, Heterogenous weld, Microstructural analysis
Vol. 15, 2021, No. 4, p. 7-10
UNNAMED VEHICLES, CONSTRUCTION AND THEIR USAGE
Author: Pavol Mikuš
Abstract: This article deals with construction of drones and materials for manufacturing of them. In next part is focused on possibilities of their usage in thermo diagnosis. This deals about technical aspects, law and from that resulted terminology, restrictions for operation and necessary permissions. In considera-tion of growing availability of UAV, technical and software equipment we could expect that we are on the beginning of new trend – deployment of UAV in field of technical diagnosis.
Keywords: UAV, Carbon, Fiberglass, 3D print
Vol. 15, 2021, No. 4, p. 11-15
THE APPLICATION OF LASER HARDENING MATERIAL
Author: Milan Jus
Abstract: This article deals with the possibilities of heat treatment of the material, rather its part, to achieve the required properties, which are required in fur-ther activity. Particular attention is paid to laser treatment.
Keywords: heat treatment, laser melting, microstructure, precipitation-hardened, laser powder bed fusion
Vol. 15, 2021, No. 4, p. 16-19
POSSIBILITIES OF DETERMINING THE FRAGMENTS SPEED AFTER DETONATION BY CALCULATION
Author: Ľudmila Timárová
Abstract: The article describes methods for determining the speeds of fragments, which arise from the division of the body of the projectile or the payload by det-onation of the working charge. The article summa-rizes the calculation methods for individual types of shells and charges. At the end of the article, the calculation of speed of the fragments, which arises during the shattering of the steel body of a 20 mm caliber projectile using a TNT filling, is given. The article also describes ways to verify the calculated values.
Keywords: Take of speed, Fragments, Explosive
Vol. 15, 2021, No. 4, p. 20-25
DEPENDENCE OF APPROXIMATION WITH THE MAXIMUM DESIGN PRESSURE TO THE YIELD STRENGHT OF THE MATERIAL AND THE APPLICABILITY OF VARIOUS TYPES OF CALCULATIONS TO THE MINIMUM SAFETY WALL THICKNESS OF THE GUN BARREL, CALCU-LATIONS FOR CALIBER 50BMG
Author: Miroslav Polášek, Matúš Danko
Abstract: For every weapon system, safety is essential for the users. The security of small caliber weapons is as-sociated to the firing sequence. The danger spots are the closing mechanism and its fortress of fire. Another essential safety feature of the use of small caliber weapons is the correct oversizing of the gun barrel of both standard and tormentational ammu-nition, especially in the case of a shot. And in this work, we will deal with the correct calculations of the minimum wall thicknesses of the barrel.
Keywords: gun barrel, barrel strength, yield strength, pressure in the barrel
Vol. 15, 2021, No. 4, p. 26-30
TESTING OF BATTERIES USED IN ELECTRIC CARS EVALUATION OF THE SMALLEST POSSIBLE CURRENT REQUIRED TO TEST THE FAULTS OF THE TRACTION BATTERY GRID
Author: Miroslav Polášek, Milan Jus, Matúš Danko
Abstract: The presented article presents the parameters of batteries used in electric cars. Measurements were performed for different types of batteries. The pro-cess of charging and subsequent discharging of these batteries took place. Different types of loads were used to discharge the batteries to find the smallest possible load current, which identifies the faults of the battery grid.
Keywords: battery charging, battery discharge, battery capacity, battery load, discharge current, power
Vol. 15, 2021, No. 4, p. 31-36
INVESTIGATION OF MICROSTRUCTURE AND STRENGTH PROPER-TIES OF INTERFACE BETWEEN INCONEL 625 WELD LAYER AND 16Mo3 STEEL
Author: Patrik Klučiar, Michal Krbaťa, Igor Barényi, Ján Palkech
Abstract: The article deals with the investigation of weld In-conel 625 layer low alloyed heat resistant 16Mo3 steel. The investigation was focused on the analy-sis of the behavior of the layer during the load by tensile strength test including strength properties evaluation of the layer – substrate system. The mi-crostructure of the system was investigated too with a focus on the interface between layer and the sub-strate.
Keywords: Weld, Tensile test, Microstructure
Vol. 15, 2021, No. 4, p. 37-42