Papers by Author: Karel Mazanec

Abstract: The present work is focused on complex evaluation of crack profiles, created around Vickers indents in two types of cutting tool ceramics, namely in the Al2O3 + ZrO2 ceramics and -Si3N4. The geometry of Vickers indents is investigated using two different evaluation methods. The first one is based on the application of serial sectioning from the indented specimen surface. The second method consists in the layer removing from plane perpendicular to the indented surface. These evaluation methods are convenient for determine the shape of created cracks and profiles of deformed area developed around the investigated indents. The mentioned methods contribute to the understanding of physical engineering principles resulting from the radial/median and lateral crack formation as the important characteristics influencing the reliable technical application of investigated ceramic materials.

Abstract: The work is devoted to the evaluation of indentation fracture toughness in ceramic materials and to the comparison of these data with the results of this characterisation obtained by the application of fracture mechanics method (chevron notched beam specimen – CVNB). The indentation fracture toughness measurement is realized using the indentation load lying in the loading extent between 50-300 N. The evaluation of basic parameters of lateral crack initiation resulting in chipping formation in the vicinity of indent is performed. This measuring is based on the finding of relationship between the indent load level and the number of loading cycles leading to chips formation. The geometry of lateral cracks and chipping morphology are described. This evaluation is complemented with the analysis of chip fracture surfaces.