Papers by Author: Bożena Bierska-Piech

Abstract: The Zinc composite coatings containing Ni powder were obtained by the electrodeposition and electroless methods. Electrodeposited Zn+Ni coatings were plated with the current density jk = 150 mA/cm2 from the zinc chloride bath containing the suspension of nickel powder. Electroless (Zn-Ni)+Ni coatings were obtained by chemical reduction of Ni2+ and Zn2+ ions from the sulphate bath containing sodium hypophosphite as a reducing agent and mechanically dispersed Ni powder suspension. The thickness of (Zn-Ni)+Ni layer was ~8 m. In order to enhance the Zn content the obtained coatings were covered with the electrolytic Zn layers of different thickness (5 m, 8 m and 14 m) – (Zn-Ni)+Ni/Zn. The thermal treatment of the obtained composites was carried out at a temperature of 320oC, during 2h in argon atmosphere. The electrodeposited coatings show the presence of Zn, Ni(Zn) and ZnO phases. The electroless coatings show the presence of Zn, Ni(Zn) and ZnO phases. The additional electrodeposition of Zn leads to the creation of dilayer coatings (Zn-Ni)+Ni/Zn. The annealing of such obtained coatings leads to the creation of Ni2Zn11 intermetalic phase. The average Ni(Zn) and Ni crystallite size before annealing is in a range of 200 Å and after annealing the size is increasing to values of 600-800 Å.

Abstract: The X-ray reflectometry (XR), as a non-destructive method, is a powerful tool in obtaining information about parameters of thin films such as thickness, average density and interface roughness. In this paper Cu/Au, Au/Cu and Cu/Ag multilayer thin films (where the total thickness is less then 1000Å) are presented. The multilayer films are obtained by thermal evaporation in a UHV system, on the silicon substrate. The experimental XR curves contained critical angle and classical Kiessig’s fringes. For these materials the density (), the thickness () and interface roughness () information for every layer separately were calculated. The experimental reflectometry curves were analyzed using the WinGixa programme X’Pert software. The values of layer density show that they are reached in neighbor density and it is connected with the creation of the Cu-Au or Ag-Cu interlayer reached into Cu, Au or Ag, respectively. The analysis of roughness show that there are comparable to roughness of substrate only for 2-3 first layers. Further the roughness of Cu, Au, Ag layers are increasing. The comparison of results show that increasing of Ag an Au roughness is bigger than Cu.

Abstract: The X-ray reflectivity measurements were used for the analyses of the SiC and SiN thin layers. Density, roughness and the thickness were determined for searching materials. The calculations and simulations were carried out using the WinGixa software. The obtained results show that the studied layers are non-homogenous and there are consist of “sub-layers” rich in Si-C, Si-N, SI-O phases. Moreover, the presence of the main amorphous phase was observed in all searching samples.

Abstract: Precipitation hardened magnesium-rare earth alloys offer attractive properties for the aerospace and racing automotive industries. The most successful magnesium alloys developed to date have been those based on the Mg-Y-Nd system identified as WE54 (Mg-5.0wt%Y-4.1wt%RE-0.5wt%Zr) and WE43 (Mg-4.0wt%Y-3.3wt%RE-0.5wt%Zr), where RE represents neodymium-rich rare earth elements. Precipitations sequence in WE-system alloys involved the formation of phases designated β”, β’, β1 and β depending on the ageing temperature. WE54 alloy with the equilibrium β-phase exhibits good ductility and medium tensile strength. The β phase precipitated in Mg-Y-Nd alloy during ageing at 300 °C was studied using X-ray diffraction analysis and transmission electron microscopy. Precipitation at 300 °C for one hour causes formation of the equilibrium β phase. This phase has an f.c.c. structure (a = 2.2 nm), which makes it isomorphous with Mg5Gd. With the prolonged ageing time at 300 °C, the volume fraction of the β phase increases and lattice parameter of the solid solution of α-magnesium decreases.