Papers by Author: Jerzy Morgiel

Abstract: The applied squeeze casting technique makes possible the local strengthening with ceramic fibers or ceramic particles of elements with Al-alloy matrices. In this paper the elaborated technology of manufacturing of porous ceramic preforms from Saffil fibers is shown and technology of squeeze casting elaborated at Wrocław University of Technology, Chair Foundry, Polymers and Automation described. There were applied the preforms characterized by porosities of 90% and 80%, what after squeeze casting with liquid EN AC - 44200 Al alloy produces the composite materials containing 10 vol. and 20 vol.% of fiber strengthening. The structural phenomena at the interface of strengthened alloy investigated with the optical and electron microscopy are discussed and the mechanical properties of manufactured composite materials are shown.

Abstract: Good dispersion of active catalytic elements, their uniform distribution on the carrier’s surface and availability for neutralised combustion gases are key factors that determine the usability of catalyst cartridges for automotive catalytic reactors. By examining the morphology of oxide films, with SEM/STEM method, obtained by oxidation of foil coated with Pt/Al two-layered system (like laminate), where an Al nanofilm is situated between steel foil and a Pt nanofilm, one can observe forked and plate whiskers growing directly of substrate. Oxide films obtained from Pt+Al composite nanofilms were formed differently (where components are intermixed). These films are marked by chaotic, mutually penetrating fine equiaxed solids and whiskers. In case of composite nanofilms the grain system obtained in the course of deposition contributed to good Pt grain refining, and due to that mostly particles from 3 to 9 nm in conventional diameter were formed. Direct contact between Pt particles and Al particles caused the partial occlusion of Pt particles with oxide in the process of Al oxidation to be effected.

Abstract: The wear mechanisms of Ti/TiN eight layered coatings ( =250nm) were investigated with ball-on-disc test. The coatings were obtained by hybrid pulsed laser deposition (PLD) technique. The wear test was done using Al2O3 ball-on-disc test at 1N/2000 cycles. Thin foils for TEM observations were cut from wear track using a Quanta 200 3D FIB (Focus Ion Beam) equipped with an Omniprobe lift-up system. The microstructure investigations were performed with the TECNAI G2 SuperTWIN FEG (200kV) transmission electron microscope. At the start of the wear the load applied to Al2O3 ball resulted in pushing-in of the coating into substrate causing its grooving of the shape corresponding to the ball diameter. The lining of the crater required strong coating deformation, which was plastic within Ti and mostly brittle in TiN layers. The vertical cracks in TiN were indeed stopped at the TiN/Ti interfaces, but reopen in lying below TiN layers. In applied wear conditions the continuity of Ti layers prevails over cracking of the TiN layers and resulted in layer-by-layer wear of investigated multilayer coating.

Abstract: Molybdenum silicides were obtained by the self-propagating synthesis (SHS) method. Diamond composites containing 30 mass% of MoSi2 or Mo5Si3 bonding phase had been prepared using HT-HP Bridgman type apparatus. Sintering of the diamond composites were carried out at 2073±50 K and 8±0.2 GPa. The interactions in diamond-silicide composites were studied by means of X-ray diffractometry and transmission electron microscopy (TEM). Results of both mechanical properties and thermal resistance measurements are reported. Hardness HV1 for the composite with the predominantly MoSi2 bonding phase was found to be around 42 GPa. After heat treatment in 1200 °C for 30 min. in vacuum HV1 decreases to 29 GPa. In the second composite containing the Mo5Si3 bonding phase the HV1 of 28.0 GPa after thermal exposure changes to 21.0 GPa.