Papers by Author: Janusz Szala

Abstract: The study presents results of electrochemical corrosion tests of extruded magnesium alloy WE43 used for stents in cardiology. Corrosion tests were performed in artificial plasma with application of the system for electrochemical tests VoltaLab PGP201. Potentiodynamic tests enabled to register polarisation curves. Scanning microscope were used for assessment of the surface of tested alloy after corrosion tests. It was proved that the alloy is susceptible to pitting corrosion. Options of magnesium alloy WE43 application in cardiology are connected with the need for application of protective layers on implants made of the tested alloy.

Abstract: The purpose of the study was evaluation of electrochemical corrosion resistance of extruded magnesium alloy AZ31. Corrosion tests were performed in NaCl solutions featuring chloride ions concentration from 0.01 to 2 M NaCl. Potentiodynamic tests enabled to register anodic polarisation curves. Immersion tests were performed in NaCl solution and time 1-5 days. Electrochemical impedance spectroscopy (EIS) was used to evaluate phenomena that take place on the surface of the tested alloy. Impedance spectra of the system were made in the tests, and obtained measurement data was matched to the equivalent system. The results of all performed tests prove explicitly deterioration of corrosion properties of extruded magnesium alloy AZ31 with the increase of molar concentration of NaCl solution. Options of magnesium alloy AZ31 application in aircraft and automotive industry are connected with the need for application of protective layers on elements made of the tested alloy.

Abstract: The purpose of the study was the evaluation of the electrochemical corrosion resistance of extruded magnesium alloy AZ61 in solutions with concentration of 0.012 M NaCl. Resistance to electrochemical corrosion was evaluated on the ground of registered anodic polarisation curves by means of potentiodynamic method. Immersion tests were performed in NaCl solution and time periods of 1-6 days. Scanning microscopy was used to obtain images of the alloy microstructure after immersion tests. Electrochemical impedance spectroscopy was used to evaluate phenomena that take place on the surface of the tested alloy. The results of all performed tests prove explicitly deterioration of corrosion properties of magnesium alloy AZ31 with the increase of molar concentration of NaCl solution. It was found that irrespective of molar concentration of NaCl solution, pitting corrosion can be detected on the surface of the tested alloy. Test results prove that it is necessary to apply protective layers on elements made of the tested alloy.

Abstract: In this paper the results of microstructural investigations and methodology of detection of intermetallic compounds were reported. The microstructural investigations included the light microscopy, scanning electron microscopy, chemical microanalysis and X-ray diffraction analysis. It was found that the microstructure of Mg-5Al-3Ca-0.7Sr-0.2Mn alloy consists of α-Mg, (Mg,Al)2Ca, Al3Mg13(Sr,Ca), Mg2Ca and Al2Ca intermetallic phases. The correct detection of these phases requires the high magnifications and a large number of measurements fields.

Abstract: All over the world the investigations of nanophotonic structures called photonic crystals (PCs) are performed. These crystals have potential applications in optoelectronics, e.g. optical filters, antireflective surface coatings, lossless frequency selective mirrors. In Institute of Physics at Silesian Technical University the opal photonic crystals consisting of monodisperse spherical particles, that have diameters of several hundred nanometers, are produced using colloidal self-assembly technics. The main aim of this work is the comparison between pieces of information on morphology of photonic crystals that can be obtained from electron microscopy and from the angular characteristics of optical transmittance and reflectance. The morphology of the samples is characterized by scanning electron microscopy (SEM). Nanosphere diameters are established from statistical analysis of SEM images. The optical properties, which are determined by the photonic band structure, are studied by means of light transmission and reflection measurements. There is a relationship between the wavelength position of transmittance minimum or reflectance maximum and the diameter of the nanospheres. The size of nanospheres obtained from optical measurement results were compared with data obtained from SEM images.

Abstract: . The paper focuses on characterization of eutectic precipitations in three magnesium alloys (MSR-B, ZRE1 and WE43) containing rare earth elements. It was shown, that the structure of the tested alloys in a cast state consists of globular grains of the α-Mg solid solution and eutectic areas of different chemical composition and morphology. An untypical influence of the pouring temperature on the eutectic precipitations area fraction was observed. This phenomenon can be explained by impoverishment of the eutectic-forming elements in the areas of the slowest solidification. This results from the fact, that at the highest pouring temperature a considerable amount of eutectic forms in places solidified as the first.

Abstract: The distance functions such as G(r), K(r), H(r), g(r) and systematic scanning method connected with variance analysis have been used for quantitative characterization of functionally gradient materials structures. The methods have been tested on computer generated 3D model polycrystalline structures with diverse type of gradient function. Usefulness of the presented methods for quantitative description of FGM structures has been evaluated.