|Tomasz Szymczak, Grzegorz Gumienny, Tadeusz Pacyniak|
The effect of tungsten on the solidification process, microstructure and mechanical properties of silumin 226 under the conditions close to equilibrium during pressure die casting was discussed. An increase in both mechanical and plastic properties of the pressure die cast silumin with 0.3-0.4 wt. % W was demonstrated.
Keywords: silumin, tungsten, mechanical properties, crystallization, ATD curves,
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Michał Angrecki, Irena Izdebska-Szanda, Aleksander Palma
The article presents the results of research on the possibilities of utilizing waste moulding sands with silicate and geopolymer binders in the production of autoclaved cellular concrete. The high content of silica in the waste moulding and core sands is a factor in favour of this technological solution. The general idea of the study was to make a series of concrete mixes, which would contain in their composition waste moulding sands, which was then introduced to the basic raw material mixture on the principle of gradually increasing the substitute of fresh silica sand. The possibility of utilization of the waste moulding sand was evaluated based on the results of comparative analysis, covering the main technological properties of the two types of materials, i.e. the base cellular concrete composed of "fresh" silica sand only, and experimental cellular concrete, where fresh silica sand was replaced in different proportions with waste moulding sand.
Keywords: waste moulding sands, utilization of moulding sands, cellular concrete, silicate and geopolymer binders,
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Janusz Faber, Katarzyna Perszewska, Maria Żmudzińska
The paper presents the results of analysis of gases formed under the impact of high temperature acting on moulding sands with the addition of selected organic resins and hardeners, commonly used in foundries as binders for these sands. As a research tool, a dedicated gas chromatograph, designed to identify specifically aromatic compounds from the group of alkanes, was applied.
Keywords: foundry binders, moulding and core sands, thermal decomposition, odours, gas chromatography,
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Izabela Krzak, Adam Tchórz
Casting manufacture depends on many factors. Technical specifications determine the required quality, which is essential for casting acceptance or rejection. Practice shows that making castings without defects is simply not possible. However, the aim is to minimize rejects owing to the use of diverse instruments for measurements and control. A tool which may be helpful in checking the internal structure of products is the X-ray computed tomography (CT). CT is a modern diagnostic method that combines X-ray examinations with advanced computer technology. Tomographic studies allow non-destructive qualitative assessment of the test material combined with advanced analysis. One of the main advantages of the X-ray computed tomography is imaging of the examined structure in three dimensions and the ability to perform spatial reconstruction.
The aim of this article is to describe the principle operation of X-ray computed tomography and offer extensive discussion of its use in various fields of science, in particular to defect detection, quantitative metallographic tests, the process of reverse engineering (reconstruction) and metrological studies. Selected examples were used to show the potential offered by this technique.
Keywords: X-ray computed tomography (CT), flaw detection, counter-gravity low-pressure air-melted casting (CLA), rapid prototyping (RP), reverse engineering (RE),
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The results of studies of quartz wettability by an ecological foundry binder are presented. Water glass modified with nanoparticles of metal oxides, such as: MgO, Al2O3 and ZnO in organic solvents (methanol or propanol) was used as a binder in the investigations. The nanoparticles were undergoing electrochemical synthesis in the process of anodic dissolution of metals such as Zn, Al, Mg. Wettability was assessed by measuring the time-related changes of the contact angle θ in a quartz-water glass system. In the measurements of the contact angle a prototype apparatus and previously developed methodology were used. Systematic tests of the quartz wettability by water glass modified with nanoparticles have indicated that this parameter depends, among other things, on the amount of the introduced modifier, and on the type of nanoparticles and type of the solvent applied. The performed investigations have proved that quartz was best wetted (small contact angle) by water glass modified with the nanoparticles of MgO and Al2O3 in propanol.
Keywords: water glass, nanoparticles, modification, wettability, moulding sands,
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In this work, an analysis of the solidification course of the AlFeMnSi alloys was carried out in the Al alloys of Fe, Mn, and Si concentrations in a range supplementary for those examined until now. The morphology of the pre-dendrite and pre-eutectic precipitates of the AlFeMnSi intermetallics has been revealed in relation to alloy composition. The phase attribution of the AlFeMnSi intermetallics forming primary pre-dendrite and pre-eutectic crystals was revealed in situ through local diffraction methods. The results obtained in the present work, as compared with data published previously, revealed the critical limit of the Mn concentration, necessary to stabilize the αc-AlFeMnSi phase as equal ≤ 0.5 wt. %, in the alloys AlFe≤3.0MnSi6 and AlFe≤1.5MnSi11 and ≥ 0.5 wt. % in AlFe≥3.0MnSi11.
Keywords: Al alloy, AlFeMnSi intermetallics, primary precipitation, solidification path,
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Renata Zapała, Sebastian Pach, Marcin Górny, Marta Homa, Aleksandra Siewiorek
The article presents the results of studies of the oxidation process conducted at 900°C for 12 hours in an atmosphere of water vapour on cast heat-resistant steel with a diversified structure (ferritic-austenitic, austenitic, and austenitic with carbides). Based on the studies of oxidation kinetics, it was found that samples were oxidized in approximation with the rules of linear law. Depending on the chemical composition and structure of tested alloys, the scale formed on the alloy surface had different properties. In the tested material characterised by a ferritic-austenitic structure, the tendency of the scale to detach from the surface of the metallic substrate was observed. It was probably due to different coefficients of the thermal expansion of austenite and ferrite.
Keywords: cast heat-resistant steel, microstructure, high-temperature corrosion, water vapour,
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Janusz Krawczyk, Edyta Rożniata, Robert Dąbrowski, Marcin Madej, Jerzy Pacyna
The work focuses on tribological tests of G200CrNiMo4-3-3 cast steel in the state without modification as well as after modification with FeSi and FeB. The FeSi modification reduced the secondary cementite precipitation in the Widmanstätten pattern and the FeB modification eliminated it. The increase in hardness and the reduction of the cementite content in the Widmanstätten pattern obtained as a result of the modification did not increase abrasion resistance. The FeSi modification resulted in an increase of the mean friction coefficient.
The obtained test results point to the fact that the modification process itself (limiting the amount of the secondary cementite precipitations) is not sufficient to improve tribological properties. It seems necessary to apply (beside modification) also heat treatment resulting in secondary cementite precipitation in the area of primary austenite grain.
Keywords: cast steel, modification, tribology, wear,
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