|Jan Szajnar, Tomasz Wróbel, Dariusz Bartocha, Marcin Stawarz
In this research paper results concerning the inoculation method based on electromagnetic stirring of hypoeutectic aluminum with silicon alloys AlSi2 and AlSi7 grade are presented. The inoculation process used a stirrer supplied by current with a high frequency, generating a rotating electromagnetic field. The efficiency of inoculation was estimated in the results of the metallographic macro- and microscopic research. Moreover, the possibility of using the obtained results in horizontal continuous casting process of Al-Si alloys was presented.
Keywords: aluminum, silicon, ingot, continuous casting, electromagnetic field,
Download 1.56 MB >>
Tomasz Dudziak, Konrad Jura
The aim of this work has been to show the influence of air oxidation and salt mist corrosion on the behaviour of low alloyed steels 18K (K18), 16M (16Mo3), 15HM (13CrMo4-4) and finally 10CrMo9-10 (10H2M) employed in the Polish energy sector. The exposures have been carried out at 450°C, 500°C, and finally 550°C for 500 hours. The obtained results indicate that in both atmospheres, the exposed steels developed similar phases containing Fe3O4 (magnetite) and Fe2O3 (hematite). The scale thicknesses developed under both corrosion conditions have indicated similar values. On the other hand, the addition of 1% NaCl - 1% Na2SO4 to deionised water generates the development of layered structures on low-alloyed steels with different Fe2O3 and Fe3O4 ratio, the effect originates most probably from the presence of S and Cl within the oxide scale. The presence of layers with different phase ratio generates the formation of stresses originating from different coefficients of thermal expansion (CTE) between the phases (Fe2O3, Fe3O4) and between the layers themselves.
Keywords: air oxidation, salt mist corrosion, high temperature,
Download 2.96 MB >>
Krystyna Pietrzak, Adam Klasik, Katarzyna Makowska, Jerzy J. Sobczak, Andrzej Wojciechowski, Dariusz Rudnik, Edmund Sienicki
The article discusses the possibilities of applying direct multiple remelting as an easy as well as substantially and economically justified method of recycling composites with an A359 alloy matrix reinforced with Al2O3 particles. Direct remelting was performed in connection with two casting procedures, i.e. with the use of gravity casting and squeeze casting. The effectiveness of the proposed methods was verified based on the selected material tests. It was demonstrated that, as a result of gravity casting, the mechanical parameters resulting from the static tensile test, up to the fifth remelting, worsen by 15%, which is a consequence of the gas-contraction porosity occurring in the case of this casting technique. It was also proved that, in the case of the use of squeeze casting, the mechanical and geometrical parameters of the microstructure, up to the tenth remelting, remain practically at the same level as in the initial state. The obtained results confirmed the possibility of using direct remelting as an alternative method for other costly recycling methods.
Keywords: composites, recycling, mechanical properties, multiple remelting,
Download 3.68 MB >>
Issues related to the characteristics and production of silica sols are discussed. The impact of characteristic parameters of the structure of silica sols with different participation of SiO2, Na2O and the values of silica modulus on density and dynamic viscosity of their aqueous solutions have been determined. In the paper are presented research results of the distribution and the size of particles distribution in particular silica sols. Photon Correlation Spectroscopy was applied for the research. Values of characteristic parameters of the structure of examined silica sols,achieved as a result of the research, enabled the calculation of the value of their WB structure uniformity index. This pointed to the influence of characteristic parameters of the structure of silica gels tested for their uniformity (homogeneity).
Keywords: silica sols, structure, photon correlation spectroscopy,
Download 1.45 MB >>
Krzysztof Regulski, Stanisława Kluska-Nawarecka
The investigations of the CastExpert system have been conducted at the Foundry Research Institute for many years now, including the following: perfecting the internal structure of the system and diagnostic procedures, enriching the knowledge base (including the use of multimedia techniques), perfecting the user interface [1-8], etc. The latest version of this system, developed as a result of further modifications, is named CastExpert++. The article describes the architecture of the system and its functions from the point of view of the user.
Keywords: expert system, knowledge base, inference, casting defects, usage scenarios,
Download 1.76 MB >>
In the research, a complex procedure was performed to determine the optimal parameters of thermal treatment of ductile iron with Ni, Cu, Mo and Mn additions which underwent austempering in order to obtain the ADI cast iron. Based on the constructed CCT and TTT diagrams, the basic heat treatment parameters were determined, i.e. the austenitizing temperature and time, the critical rate of cooling down to the isothermal transformation temperature and - for the selected values of the austempering temperature - the austempering times. It was established that, for the isothermal transformation temperature above 400°C, the processing window is closed.
The analysis of the TTT diagram makes it possible to select the time of the isothermal transformation in complex cyclic variants of the ADI thermal treatment.
Keywords: ADI, ausferrite, CCT diagram, TTT diagram,
Download 2.53 MB >>