Solid State Phenomena Vol. 226

Abstract: Characterization of top surfaces of WC-Co coatings obtained during deposition process of high velocity thermal spraying type was showed in this article. The feedstock powder was so called “superfine” powder of WC-17Co types produced by Inframat. In first part of article short characterization of powder was presented, especially characterization of it morphology including shape, internal microstructure and grain size description. The second part of article is dedicated to characterization of microstructure and topography of top surface of coatings deposited by two different methods of high velocity thermal spraying. In this case analysis of top-surface condition by scanning microscopy with chemical analysis in microareas was used and as well as a qualitative and quantitative analysis of topography of carbides surface by traditional non-contact and laser profilometry.

Abstract: In the paper the results of tests on obtaining ZnAl23Si coatings on low-silicon steel by use of the batch hot dip method have been presented. The growth kinetics of coatings obtained in a ZnAl23 bath with the content of 1% and 2% of Si has been defined. The structure has been developed, the chemical composition of particular structural components of the coating and its phase composition have been established. It has been determined that coatings obtained in the ZnAl23Si bath are continuous and they have uniform thickness. The presence of silicon in the bath allows to reduce excessive coating thickness. The coating is composed of an external layer which is formed by the bath components and of a diffusion layer of the intermetallic FeAl₃ phase.

Abstract: In the article the manufacturing of new- elaborated thermally sprayed coatings are presented. the structure, chemical or phase composition and selected results of the friction tests of the new elaborated coatings were presented. The microstructure of coatings was obtained by LM microscopy. The presented results confirm, that the new coatings can be used to basic protection to wear condition in the energy boiler.

Abstract: Article presents the state of knowledge relating occurrences of liquid metals embrittlement. The results of experimental investigations of the LME phenomenon, reasons of its formation and influence of different parameters are described. In order to determine the basic mechanical properties of materials intended for research static tensile test was performed. Samples made of C66D and C70D steels with tensions stretching (500-800 MPa) at different values and kinds of loading during the hot dip metallization were investigated. Coating processes were made in zinc with 0.5% Bi addition and results were compared to zinc coating. The processes of hot dip metallization were done at 450°C temperature and immersion time 180 s. Coated samples were investigated by light microscope to specify possibility appear of LME effect.

Abstract: In the paper the author present the results of tests on obtaining zinc-aluminum coatings on the 23MnNiCrMo52 steel used for produce coil chains for the mining industry. The coatings was obtained in the eutectic zinc aluminum bath. The growth kinetics of the coatings has been defined, their structure has been developed and the chemical composition of particular structural components of the coating has been established. It has been determined that the obtained coatings are continuous and uniform and their morphology not depends on the chemical composition of the steel.

Abstract: The microstructure and corrosion behaviour was studied for a diffusion β-NiAl and Si modified β-NiAl coatings formed on the superalloy MAR-M 247. First type, β-NiAl coating was applied with the help of method “out-of-pack”. Second type, Si modified β-NiAl coating was applied by method “pack-cementation”. Diffusion coatings created protective, heat-activated layer which separated superalloy from aggressive environment. Corrosive environment was created by tablets Na₂SO₄ at 900°C. Technique of scanning electron microscopy/energy dispersive X-ray analysis (SEM/EDS) was used to characterize the corrosion products. Experiment confirmed the advantages relating to the application of diffusion coating in aggressive environment which imitated environmental condition during operation of turbine engine. This experiment was made in cooperation with company PBS Velká Bíteš a. s., Velká Bíteš, Czech Republic and The Silesian University of Technology, Faculty of Materials Science and Metallurgy, Katowice, Poland.

Abstract: The purpose of this publication is to evaluate the scope of the changes implemented in the steel enterprises operating in Poland within the presented issue. The paper presents the components of the client centricity strategies in steel manufacturing companies belonging to global groups. Placing the client in the centre of attention is becoming an increasingly common element of the strategy of many enterprises, including steel works. Implementation of the "client in the center" concept in the organization is a complex task and is based on: changes of processes, measurement of customer satisfaction levels as well as building employee engagement.

Abstract: The research on the process of steel filtration from non-metallic inclusions is currently entering the last phase of industrial experiments. Their positive effects confirm the previous theoretical assumptions and laboratory tests. The application of steel filtration as a permanent technological operation in the process of steel casting will remarkably improve its metallurgic purity. An additional advantage will be diminishing the probability of covering the outlet nozzle of a tundish. This paper presents an outline of the experiment results mentioned above.

Abstract: The material conception of manufacture new coatings with high dispersion phases are presented. The coatings were obtained by thermally sprayed technology. The results of the hot temperature oxidation test of the new elaborated coatings were analyzed and compared. The reaction rate constant was calculated. The mass chance as a function of spallation process were recorded The microstructure of coatings was obtained by LM microscopy. After corrosion tests, the presented coatings were investigated in respect of the changes on the surface like: pits, cracks as well as oxidation layers. The results have been stored using digital imaging techniques, Nikon and PC. The presented coatings can be used to basic protection to wear and corrosion condition in the energy boiler.

Abstract: The classical models to optimize the batch of electric arc furnace require precise and predetermined numerical values. In order to determine the scrap steel properties (eg. chemical composition), we are not able to define these values precisely and accurately. This situation is due to the heterogeneity and specificity of this material, which is related to its origin and way of obtaining. Therefore the usefulness of classical models to optimize the batch of electric arc furnace is limited. The fuzzy numbers with trapezoidal membership function were applied as a model in order to describe the technological process of steelmaking, which is neither accurate nor of ambiguous nature of the parameters. The advantage of trapezoidal numbers is a simple algorithm of arithmetic operations as well as easy and intuitive interpretation. The structure of optimization model with fuzzy parameters is similar to the classical linear optimization model of the mixtures composition. The optimization model, that is formulated on the fuzzy ranges arithmetic principles, allows to ensure that the quality parameters of the batch mix for the electric arc furnace are as precise as the ones described by electro-steel works, even though the quality parameters of scrap steel as well as some of the parameters of steel melting technological process are described ambiguously.