Papers by Author: Gabriela Kostiuková

Abstract: The paper presents the results of material analysis of material of the main bearing of the underground mine hoisting engine, which degraded after a time shorter than the guaranteed service life. The material analysis was performed using metallographic and electron microscope analyses. Cutting of the samples was made by water jet in order to avoid affecting of the structure.

Abstract: This article deals with the study of defects in steel wire. In the study we model magnetic fields around rope genetated by magnetized part of rope. The work is based on the finite element program ANSYS. For the purposes of the experiments we consider one strand wire rope construction. We define different kinds of defects and faults. The shape of the magnetic induction lines of generated fields depends on the size of the defect, the depth of rope violation or the presence of other nearby defects. The location and number of disturbances have been chosen to achieve the most versatile outputs. All of these modifications were analyzed and the results displayed in the 3D colored.

Abstract: Problems of reactive diffusion at the solid phase and melt contact are studied theoretically. The rate constant is a fundamental parameter characterizing the dissolving rate at a certain configuration of experiment. Relationships between the solid phase dissolving rate, i.e. the solid phase interface boundary movement in the melt, and rates of growth of intermetallic phases in the metal (Cu) are observed. This procedure enables the creation of surface and subsurface layers of regulated thickness in metallic materials by means of reactive diffusion. The main intention was an experimental study of copper dissolving in melts of various solder alloys and the related reactive diffusion. We used Sn, SnCu, SnAgCu, SnZn and SnIn alloys as a solder material. The problems that need to be solved preferentially are emphasized. It concerns especially the determination of the rate constant of dissolving and verifying whether the proposed model equations can be used for this constant determination in cases of cylindrical and planar dissolving. Rapid growth of phases in the metal (Cu) and determination of the thickness of layers with these phases pose considerable time demands to X-ray microanalyses (WDX, EDX, BSE, SEM) of specimens after their long-time heating.