Solid State Phenomena Vols. 203-204

Abstract: Abstract. The polycrystalline compounds in the ZnCr2-xNdxSe4 system were prepared by the ceramic method in closed silica tubes using ZnSe, Nd2Se3, and Cr2Se3 as starting materials. The chemical composition and structural data has been determined by X-ray diffraction. The observed symmetry is cubic, space group . For ZnCr1.95Nd0.05Se4 compounds, a pure spinel phase forms for stoichiometric and smaller amounts of ZnSe. For both compounds of ZnCr1.90Nd0.10Se4, near spinel phase, a foreign ZnSe phase exists. It may indicate that 10% doping is close to the solubility limit of Nd in ZnCr2Se4.

Abstract: The most important structural parameters of semicrystalline polymers can be determined by modeling of their structure and best fitting of a theoretical intensity distribution calculated for the assumed model to the experimental SAXS curve. This paper presents a module of a computer program SAXSDAT dedicated to such calculations.

Abstract: Most frequently, the degree of crystallinity of polymers is determined using Wide Angle X-ray Diffraction (WAXD) technique. The method consists in the resolution of WAXD diffraction curve of a polymer into individual crystalline peaks and amorphous halo. This work presents a procedure, which was elaborated to help in a quick determination of the angular positions of crystalline peaks present in the diffraction curve of investigated polymer. The positions of peaks are determined using numerical differentiation. Using these data the computer program WAXSFIT identifies investigated polymer and prepares a set of starting parameters which are used in the calculations of the degree of crystallinity.

Abstract: In this paper we have obtained CdCrTe thin layers by PLD method using the YAG:Nd3+ laser with pulse length 250μs. Synthesized CdCrTe solid solution with 50% at. of Cr has been taken as a target. The layers were deposited on KCl substrate. The target and films were analyzed using X-ray diffraction, TEM microscope and THEED electron diffraction. The morphology of the layers are homogenous. However, we have detected several crystallographic phases: cubic CdTe, hexagonal Cr and hexagonal Te. From the measurements of lattice constant of the layer, their composition was determined to be x=0,14

Abstract: Thin films and coatings are applied to engineering materials in order to improve the mechanical properties of the surface, such as wear resistance, corrosion resistance and hardness. This research work deals with coatings deposited by appliance of the Physical Vapour Deposition method (PVD). The presented instigations concerning the production of coatings are one of the present important directions connected with modern surface engineering, ensuring the obtainment of coatings of high usable properties like mechanical characteristics and wear resistance. The general purpose of this work is investigation and evaluation of the obtained Ti/(Ti,Si)N/(Ti,Si)N coatings on magnesium cast alloys using electron microscope as the main investigation tool. The investigations were performed using scanning and transmission electron microscopy for the microstructure determination, also EDS microanalysis and electron diffraction was possible to obtain. While investigating the coating material, there were studied the transition zone between the coating and the substrate material as well the occurrence of some structure defects which can be present after the deposition process and could have any influence of the properties of the achieved coating. Also the structure character will be investigated for the occurrence of the nanostructure coatings, which could be seen as the solution of this issue. In the present work, the goal is set on current practices and future trends for nanocomposite thin films and coatings deposited by physical vapour deposition (PVD) technique. This investigation will touch some aspects of such coatings, but the main objective is to give a general view on features revealed using electron microscopy application in PVD coating investigations.

Abstract: The paper presents results of studies on the phase composition, crystallite sizes and lattice deformations of oxide layers formed during a long-term operation on X10CrMoVNb9-1 steel. Test specimens were taken from a live steam pipeline operated at 535°C for 70,000 hours. X-ray studies were carried out on the tube outside surface (on the flue gas side), then the layer’s surface was polished and the diffraction measurements repeated to reveal differences in the originated oxides layer. X-ray phase analysis was performed using a SEIFFERT 3003 T/T X-ray diffractometer, with a cobalt tube of λ_Co = 0.17902nm wavelength. crystallographic database were used for the phase identification.

Abstract: The analysis of Auger electron and electron energy-loss spectra was developed to determine an elastic modulus and a relative permittivity of the diamond and tetrahedral amorphous carbon layers (both on the substrate of NiTi alloy), the graphite and graphite-like carbon layers in a carbon/oxidization/ TiNi systems. The description of line-shape carbon Auger spectrum is based on the convolution of two-conduction electron and one-core electron spectral densities. It was concluded that the comparisons of the experimental and theoretical Auger spectra were determined the quantitative assessment of the electron-electron repulsion, which allow us to calculate the relative permittivity of the layer. The analysis of electron plasmon losses was applied to determine the values of plasma energies of the layers. Such parameter values were as then applied to calculate the values of nanoscale properties. The results demonstrated that the property values of the carbon layers were in good agreement with that reported in literature.

Abstract: The chitosan (CH) coatings on a Ti13Zr13Nb alloy substrate were obtained by electrophoretic deposition (EPD). The EPD yield was investigated under different deposition conditions. The microstructure of the CH coatings obtained by cataphoresis was studied by scanning electron microscopy and the chemical composition was examined using EDAX. The functional groups and formed phases were analyzed using Fourier transform infrared spectroscopy and X-ray diffraction, respectively. It was found that the CH coating thickness and porosity can be controlled by time and voltage used for the EPD process. It was ascertained that the studied EPD of the natural biopolymer, chitosan, in aqueous solution is applicable for the surface modification of the Ti13Zr13Nb implants to develop novel bioactive coatings.

Abstract: The Zn-Mn coatings were deposited under galvanostatic conditions from a sulfate galvanic bath. The influence of thiocarbamide additions in the bath on surface morphology, chemical and phase composition and corrosion resistance of the electrolytic Zn-Mn coatings was investigated. On the basis of these investigations it was found that Zn-Mn coatings can be obtained by the galvanostatic method. Morphology and chemical composition of the electrolytic Zn-Mn coatings depend on the thiocarbamide concentration in the galvanic bath. XRD investigations of obtained coatings showed a single phase structure (α-Mn_1.08Zn_2.92). The additions of thiocarbamide improve the protective properties of the Zn-Mn coatings.

Abstract: The article presents the experimental trial to connect aluminizing methods: VPA and CVD. Inconel 713 alloy was used as the base material. The purpose of the process was to obtain a layer modified with more Zr than the coatings deposited by CVD. The conducted tests revealed intercrystalline corrosion in the area of β-NiAl phase granules, which indicates that precise selection of processing conditions is the key factor for Zr-modified aluminizing. The resultant microstructural faults of the layer, however, didn’t impair the properties PS-PVD-deposited ceramic layer. The zirconium content in the outer zone equalled 2-3 at.%. in the second variety of the process. In future the described coating may form an alternative for Pt-modified aluminide coatings.