Solid State Phenomena Vol. 199

Abstract: Measurement results of the research aimed at plasma spheroidization of a mixture of W-re powders are presented in the paper. Such powders may be a good prefabricated unit for production of W-Re sinters or materials comprising, besides W-Re, also other metals like Fe, Ni, Co, and so on. The influence of plasma spheroidization parameters on the powder oxidization level, and the process effectiveness are shown. Moreover, measurement results of powders oxides reduction after plasma modification are presented.

Abstract: Aluminum-copper alloys (Al-Cu) are nowadays widely used in various applications, mainly in automotive and aviation industry, because of their unique properties such as high strength, low density and good corrosion resistance. However, usages of aluminum alloys are partially limited due to their reduced hardness, wear resistance and poor tribological parameters. Desired useful parameters can be improved by application of PA CVD technology. This work presents the results concerning determination and analysis of the structure and the selected properties of the modified surfaces of Al-Cu alloys (2xxx series) that were prepared using plasma assisted MW CVD (Micro-Wave Chemical Vapour Deposition) method. To ensure effectiveness of the substrate modification process, the covered surface was subjected to pre-treatment with argon plasma and/or nitriding process. In conclusion, the research has confirmed that the wear resistance of the Al-Cu alloy can be successfully modified by application of MW CVD technique. The obtained results can serve as a basis in the design of the technology of a-Si:C:N:H layers for diverse applications.

Abstract: The method of active thermography is an innovative NDT technology that was developed over the recent years to investigate microstructure condition of machinery components, including components of gas turbines. The essence of the method consists is examination of the thermal response of a material as a function of time to simulation by means of an external heat pulse. When the microstructure contains areas that differ in thermophysical properties, such differences entail alteration of the diffusion velocity. Therefore monitoring of the temperature field that spreads on the surface area of a workpiece that is being cooled down makes it possible to find locations of such different areas. The paper outlines initial results of investigations, carried out with use of the active thermography, how the temperature affects onto thermophysical properties demonstrated by superalloys used for construction of gas turbines. These investigations enabled to find out variations of thermophysical properties of these superalloys as a function of temperature. Eventually they laid down the fundamentals to undertake broader research studies in that domain. The core objective of the studies was to find out the relationships between variations of the thermal impact and corresponding amendments in the response signal received from the investigated material and to detect the correlations that have not yet been defined with sufficient accuracy. The described relationships and liaisons may contribute to development of fundamentals for the new NDT thermographic method suitable to evaluate the overheating status of gas turbine blades.

Abstract: The paper presents investigation results for obtaining a semi-finished product in the form of round Al-Cu bimetallic bars by the explosion method. The systems and technological parameters of explosion welding were selected in such a manner as to obtain finished bimetallic bars of an outer diameter of approx. 22 mm and a copper area fraction of the bimetal cross-section of approx. 15 and 30%. In this work was made an analysis of microstructure changes and the microhardness distribution on the cross-sections of the stock materials. There were also made tests of layers connections quality by determining the maximum shear stress on the joint boundary. The results show that the explosive cladding method guarantee a permanent connection of copper layers and aluminum core.

Abstract: As part of this work the analysis of the impact relative rolling reduction at the connection area of bimetallic plate after the rolling process was carried out. The rolling process was conducted on samples that have been joined by explosive welding method [1-. The scheme of joining bimetallic plates with use of explosive welding method is shown in fig. 1 [. Geometric and structural design of explosively welded connections depends on the type of welded metal, welding process parameters and the thickness of welded components, the geometry of collision, the type of substrate and surface preparation. Regardless of the type of welded metal, there are three basic types of connections obtained with different parameters of welded plates: flat connections without an intermediate layer of the symmetric deformation of grains, wavy connections and the last one with continuous intermediate layer. This paper presents the analysis of sheet metal connection area after direct double-layer combining by explosive welding method and the next stage of their production - the rolling process. Bimetal plates Al99.8-M1E were rolled with relative rolling reduction ε = 10%, 15% and 20%. The analysis of structural changes was made for both kinds of the samples: after the direct connection and after the annealing operations. In addition to analyzing the results of optical microscopy to present a complete picture of changes in the joints the Vickers micro hardness testing were carried out. Fig. 1. Scheme mergers bimetal plate explosive welding method [5]

Abstract: The requirement for curde oil and natural gas is still increasing. It was observed a growing of interested in the exploration and exploatation of unconventional fuels, including shate gas. There is about 3 to 5 trilion cubic meters resources of that type of gas in Poland. The latest data predicts that in addition to gas in the shale is also petroleum. The development of this branch of mining in our country can cause a significant increase in demand for pipes. The results of basic research of experimental steels for pipe line are presented in this article. Analyse of published materials about steels for pipe line was done. The chemical composition of two types of new steels meeting the requirements for X80 and X100 grade plates according API 5L norm were developed. The heat tratment using dilatometer DIL 805A/D were carried out. The influnce of heat temperature before rolling proces on structure of austenite was defined. The heating schemes were proposed for obtaining a high yield, while not allowing the dissolution of the alloying elements inhibit austenite grain overdevelopment. For samples after tests the structure of primary austenite and the size of former austenite grains were determined. The influence of deformation cinditions on structure were determinated, too. The results obtained from the examinations will be used to develop a technology for rolling sheets of pipelines in the category of X80 and X100 according to the API.

Abstract: The increasing demand by the automotive industry has resulted in a search for materials of increasingly high mechanical properties and, at the same time, plastic deformability. These requirements are met by AHSS (Advanced High-Strength Steels) multiphase steels. The group of AHSS type steels may include: diphase (DP), TRIP-effect, hot formed (HF) martensitic, plastic formed heat treated (PFHT), and TWIP-effect steels.

Abstract: This work presents application of the methods of combined analytical techniques: high performance capillary chromatography and mass spectrometry with a nanoelectrospray ion source (nanoESI) for biochemical analysis of biological films. The layers of biofilm (identification of surface proteins) adsorbed on surfaces of metallic plate fixation and metallic screws surfaces used during treatment of the mandibular fracture were investigated. The obtained results make it possible to determine the protein composition of films found on the plates and screws used for fixation of the mandible. Second part of the work involves microscopic observations of specially prepared parts of tissues contacting directly with time-part implant. We observed changes in the osseous tissues and relocations of the metal ions from the fixations using a Hitachi S-3000N scanning microscope, equipped with an NSS type (Noran System Six) X-ray spectrometer and a freezing table for biological sections. Obtained results indicate the penetration of metal ions from the time-part implant surface into the osseous tissue.

Abstract: The paper presents changes in UHMWPE morphology and structure induced by exposure to a beam of electrons and thermal processing applied after the modification through irradiation. Two groups of samples were tested: those that underwent modification through irradiation only and those that underwent a sequential process which consisted of radiation modification and thermal processing. The obtained variants were subjected to comprehensive morphological and structural tests, which made it possible to: document changes in the lamellar structure (SEM); determine the content of crystalline phase (DSC); determine the degree and density of crosslinking; state the degree of polymer oxidation (FTIR); examine the influence of the irradiation dose on the intensity of free radicals occurrence (EPR) and to determine the effectiveness of their elimination using recrystallisation in an oxygen-free environment.

Abstract: The paper presents the results of the EPR examination of free radical content in GUR1020 and GUR1050 polyethylenes which were irradiated with an electron beam. Changes in the amount of radicals in the period of 12 months in the UHMWPE cross-linked with a dose of 26-156 kGy were analysed. Spectra registered 90 days after irradiation show a hyperfine structure. An image consisting of 7 characteristic lines is the most similar pattern that can be used to analyse this spectrum. Subsequent measurements (255 and 372 days after irradiation) produce images consisting of one resonance line. Alkyl and allyl radicals generated during the irradiation are the source of the EPR signal. The influence of atmospheric oxygen causes further changes of the radicals mentioned above, which leads to the formation of peroxyl radicals. The content of radicals in the polymer and its changes over time were calculated. The amount of radicals increases as the absorbed dose grows, but decreases over time. Comparative measurements of the material subjected to thermal processing at the temperature of 423 K have shown that in this case, no resonance lines are present, which testifies to the effective elimination of free radicals by means of UHMWPE recrystallisation.