Kazimierz Reszka

Structure and Catalytic Testing of Hybrid Al2O3 Systems Deposited on Heat Resisting Steel Substrate by High-Temperature Oxidation and PVD Methods

Catalytic combustors for automotive presents a basic problems with obtaining the well developed oxide surface marked by the occurrence of acidic and basic sites and performing the function of the catalytic element carrier. The paper includes the comparison of structure and catalytic properties of: - Al2O3 films obtained by oxidizing the foil made of 0H18J5 alloy in the presence of SO2, at the 1093K , - Al2O3 films obtained by oxidizing the foil, coated firstly with an Al film, in the presence of Ar+50%O2 at the 1133K, - Al2O3 film systems obtained by oxidizing the foil in the presence of Ar+50%O2 at the 1133K, then coated an Al nano-film and again oxidized under the same conditions, - Al2O3 film systems obtained, as previously, by oxidizing the foil, which was firstly coated with an Al2O3 nano-film by reactive magnetron sputtering. The catalytic activity of deposited films was determined from the basic sites identified by 2-methylol-3-butyn-2-ol conversion into acetone and acetylene, and from the acidic sites identified by its dehydration into 2- methylol-1-buten-3-yn.The structure analysis of the oxide films obtained by oxidizing under SO2 revealed the occurrence of θ-, γ- and α-Al2O3 phases, however the oxide films obtained by oxidizing the foil with an Al precursor in the presence of Ar+50%O2 contained a small amount of hematite. The catalytic test revealed that the films containing θ- and γ -Al2O3 have acidic and basic sites and their catalytic activity is high, whereas α-Al2O3 and amorphous films do not show such the activity.

Morphology and Electromagnetic Shielding Effectiveness of PP Nonwovens Modified with Metallic Layers

Polypropylene (PP) nonwoven was used as a substrate for CuSn and CuZnNi deposited layers. Nonwoven metallization was carried out using the DC magnetron sputtering process at various process parameters (e.g. effective power dissipated in the target, velocity of the substrate drift, number of cycles). The studies aimed at defining the surface morphol ogy of PP nonwoven modified by metallic deposition, the crystallographic structure of the thin metallic layers and the effect of the layers’ crystallinity on the electromagnetic (EM) shielding effectiveness of the two-component metal/PP composites. The morphology studies were covered by scanning electron microscopy. Furthermore the crystalline character of components CuSn and CuZnNi was examined in grazing-incidence angle X-ray diffraction experiments. It was found that CuSn/PP composites with a crystalline structure of the metallic layer exhibit the highest values of shielding effectiveness (44-45 dB at 27,12 MHz and 38-39 dB at 1795 MHz).

Surface modification of polypropylene nonwoven with composite metallic layers

Polymer fibres have the great potential for application due to their large surface area relative to volume, incomparably large length relative to the cross-section, high strength and ease of forming the nonwovens in thermal processing. Due to the specific properties of textiles, they are applied, among others in the manufacture of filters, sensors, biomedical devices and protective clothing. This study was aimed to evaluate the surface morphology of polypropylene nonwoven modified with metallic layers CuSn, CuZnNi, NiCuFe, deposited by the magnetron sputtering technique. There was also carried out a qualitative and quantitative analysis of deposited thin layers and their compositions were compared with compositions of targets used for magnetrons. The surface morphology was tested using the metallographic optical microscope with a CF160 optical system and the scanning electron microscope adapted to work in an environmental mode. A study of composition was based on a microanalysis using the energy dispersive X-ray radiation deriving from the excited atoms (EDS).

Oxide Films Produced on Fe19Cr5Al Steel Coated with Al, Pt and Al+Pt Composite Nanofilms: Technological Aspects and Catalytic Properties

K. Reszka, Z.śurek, J.Morgiel, J.Rakoczy Koszalin University of Technology, Institute of Mechatronics, Nanotechnology and Vacuum Technique, 75-620 Koszalin, Raclawicka st.15-17, Poland Technical University of Kraków, Department of Inorganic Chemistry and Technology, 31-422Kraków, Warszawska st.24 Poland Institute of Metallurgy and Materials Engineering PAS, 30-059 Kraków, Reymonta st. 25, Poland Technical University of Kraków, Department of Organic Chemistry and Technology, 31-422Kraków, Warszawska st.24, Poland kazimierz.reszka@tu.koszalin.pl zzurek@chemia.pk.edu.pl nmmorgie@imim-pan.krakow.pl jrakoczy@usk.pk.edu.pl

The influence of Kanthal wire surface defects on the formation of Si nanolayer deposited by PVD method

Abstract The subject of this research is the structure of a Si nanolayer deposited on a FeCrAl wire surface by means of magnetron sputtering method. Si layer was selected as one of possible protections of the wire surface against excessive corrosive-erosive wear. In order to increase the power necessary for the DC discharge of the magnetron with Si cathode, a second magnetron with an aluminum disc as a cathode was used. The wire was attached to a carousel holder to ensure its rotation around the magnetron. The thickness of the deposited layers was about 150 nm. A wire surface examination indicated the presence of defects such as gaps between grains, cavities as well as severely deformed grains of surface layer. The research was conducted on the sample sections which had been prepared by focused ion beam method (FIB). The technique of transmission microscopy, which was used for observation, allowed us to obtain images in bright field (BF), dark field (DF), as well as in high resolution (HREM). The studies were also performed on the wire surface after the cutting process of the expanded polystyrene blocks. A metallographic optical microscope Nikon MA200 with a large depth of field was used for the examination which showed the presence of carbon deposit products. Additionally, a composition microanalysis was carried out along the line within selected areas of samples, with the use of energy dispersive spectroscopy (EDS). A large impact of wire surface defects on Si layer forming was found as well as a high direct homogeneous growth. The examination of the sections indicated the existence of a mechanism of defects sealed by Si layer, where directionality of grains growth in these areas revealed the tendency for vertical location relative to defects surface. Consequently, closed nanopores, i.e. spaces not covered with Si layer, were created. It is a characteristic feature of areas with defects covered with an oxide film created in a natural way.

Nickel Porous Electrode Pt Layered by PVD Method

Influence of a platinum layer on the nickel powder sintered electrode on electrochemical processes of hydrogen generation is presented and discussed in this paper. The sinters of metallic nickel with developed area were obtained by subsequent oxidation/reduction of Ni powder. The process of platinum layer deposition on surface of nickel sinters was carried out with the PVD method. The morphology characteristics of Ni and Ni-Pt layered sinters were carried out with the application of SEM/EDS method. The electrochemical properties of above mentioned sinters were examined by potentiostatic method at 40°C in 1M KOH vs. Hg|HgO, using a rotating disc electrode. It was found that the platinum layer on the surface of nickel grains was well adherent and stable. The presence of platinum on nickel sintered electrodes results in an increase of observed current density in the process of hydrogen evolution.

Oxide Films Formed on FeCrAl Steel Foil Coated with Pt and Al Films

The investigations were aimed to characterize the oxide films (Al2O3) in terms of the crystal structure development and their impact on increase in mechanical distribution of Pt in volume of the film, as a system predisposed to carry out catalytic processes. The morphology and phase composition of oxide films formed on the surface of FeCrAl steel foil coated with Al and Pt films and Al/Pt composition films after oxidation at high temperature were investigated. All samples with films were oxidized in an atmosphere containing 67% O2/Ar at 850 ° C in a period of 24 h. As a result of the oxidation processes there were formed θ-Al2O3 oxides of whisker structure of a considerable size, while whiskers of θ-Al2O3 oxides formed on the samples coated with Pt films were smaller but with higher density. There was also α-Al2O3 phase in the form of solids in the immediate vicinity of the steel substrate.

Application of SEM/TEM to Tests on Pt Distribution in Al2O3 Films Obtained by Oxidising FeCrAl Steel Foil Coated with Pt-Al Nanofilms

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.