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Fima P.,Poland Foundry Research Institute | Fima P.,Polish Academy of Sciences
Applied Surface Science

The surface tension and density measurements for Sn-Ag alloys were carried out with the sessile drop method. Seven different compositions were investigated in the range from 0.011 to 0.5 mole fraction of Ag, in a broad range of temperature. With increasing concentrations of Ag, both density and the surface tension are increased. With increasing temperature the density decreases for all of the alloys. A decrease of the surface tension is observed for most of the composition except for the alloy of 0.5 mole fractions of Ag. The obtained results are compared with existing literature data and Butler model calculations and relatively good agreement is observed. © 2010 Elsevier B.V. All rights reserved. Source

Pirowski Z.,Poland Foundry Research Institute
Archives of Foundry Engineering

Superalloys show a good combination of mechanical strength and resistance to surface degradation under the influence of chemically active environments at high temperature. They are characterized by very high heat and creep resistance. Their main application is in gas turbines, chemical industry, and in all those cases where resistance to creep and the aggressive corrosion environment is required. Modern jet engines could never come into use if not for progress in the development of superalloys. Superalloys are based on iron, nickel and cobalt. The most common and the most interesting group includes superalloys based on nickel. They carry loads at temperatures well in excess of the eighty percent of the melting point. This group includes the H282 alloy, whose nominal chemical composition is as follows (wt%): Ni - base, Fe - max. 1.5%, Al - 1.5% Ti - 2.1%, C - 0.06% Co - 10% Cr - 20% Mo - 8.5%. This study shows the results of thermal analysis of the H282 alloy performed on a cast step block with different wall thickness. Using the results of measurements, changes in the temperature of H282 alloy during its solidification were determined, and the relationship dT / dt = f (t) was derived. The results of the measurements taken at different points in the cast step block allowed identifying a number of thermal characteristics of the investigated alloy and linking the size of the dendrites formed in a metal matrix (DAS) with the thermal effect of solidification. It was found that the time of solidification prolonged from less than ome minute at 10 mm wall thickness to over seven minutes at the wall thickness of 44 mm doubled the value of DAS. © by Z. Pirowski 2015. Source

Adamczyk Z.,Polish Academy of Sciences | Nattich-Rak M.,Polish Academy of Sciences | Sadowska M.,Polish Academy of Sciences | Michna A.,Polish Academy of Sciences | Szczepaniak K.,Poland Foundry Research Institute
Colloids and Surfaces A: Physicochemical and Engineering Aspects

Particle deposition phenomena were theoretically analyzed in terms of a hybrid theoretical approach where the bulk transport is described by continuity equations and the surface transport by the random sequential adsorption (RSA) models. RSA modeling furnishes maximum coverages and blocking functions for spherical and anisotropic particles. These parameters are used as boundary conditions for the bulk transport equation. This enables one to derive theoretical results describing kinetics of convection and diffusion-controlled transport of particles to interfaces, which is discussed next. The utility of this theoretical approach is confirmed by experimental data obtained for various colloid systems involving micro- and nanoparticles using optical and fluorescence microscopy AFM, SEM and TEM imaging of particle monolayers. Comparison of theoretical and experimental results shows that the electrostatic interactions play a dominant role affecting the maximum coverage of and the structure of deposited particle monolayers. Particle deposition on heterogeneous surfaces formed by a controlled deposition of nanoparticles and proteins (latex, hematite, fibrinogen) is also considered. These phenomena are properly interpreted in terms of the RSA model considering fluctuations in the particle density. The classical DLVO theory, based on the mean-field (averaged) zeta potential concept proved inadequate. It is also shown that the colloid particle deposition on protein monolayers can be used to efficiently determine the coverage and a real charge distribution under wet, in situ conditions. It is concluded that particle and protein deposition phenomena show deep analogies. This suggests that the results acquired for nanoparticles can be used as convenient reference systems for interpretation of molecular adsorption phenomena inaccessible to direct measurements. © 2013 Elsevier B.V. Source

Fima P.,Polish Academy of Sciences | Fima P.,Poland Foundry Research Institute
International Journal of Materials Research

The surface tension and density of Sn-Ag-Cu alloys, lying along two cross-sections of silver to copper molar ratios equal to 1 and 7/3, were studied. Sessile drop measurements were carried out over a broad temperature range. It was found that both surface tension and density decrease with increasing concentration of Sn. With the increase in temperature, the density decreases linearly for all compositions, whereas the surface tension shows linear and curvilinear dependence for different compositions. The results are compared with literature data obtained with a different technique and the results of model calculations. Relatively good agreement is observed between the models and experimental data. © 2012 Carl Hanser Verlag GmbH & Co. KG. Source

Sobczak J.J.,Poland Foundry Research Institute | Drenchev L.,Bulgarian Academy of Science
Journal of Materials Science and Technology

Functionally graded materials, including their characterization, properties and production methods are a new rapidly developing field of materials science. The aims of this review are to systematize the basic production techniques for manufacturing functionally graded materials. Attention is paid to the principles for obtaining graded structure mainly in the metal based functionally graded materials. Several unpublished results obtained by the authors have been discussed briefly. Experimental methods and theoretical analysis for qualitative and quantitative estimation of graded properties have also been presented. The article can be useful for people who work in the field of functionally graded structures and materials, and who need a compact informative review of recent experimental and theoretical activity in this area. © 2013. Source

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