The article discusses the ways of modification of hydrated sodium silicate as a silicate binder of moulding sands which were applied in the studies. It determines the change in the residual strength of the moulding sand with used silicate binders as well as the effectiveness of the changes in the residual strength as a function of the annealing temperature of the examined moulding sand samples. It was established that the most advantageous binder with regards to changes in the residual strength of the moulding sand is a silicate binder chemically modified with an organofunctional addition as well as a geopolymer binder, whereas the most beneficial effect of the changes in the residual strength of the moulding sand is ensured by a silicate binder chemically modified with an organofunctional addition.
Keywords: hydrated sodium silicate, geopolymer, moulding sand, residual strength,
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Mieczysław Kuder, Krzysztof Jaśkowiec
The study involved the preparation of seven melts of spheroidal cast iron solution reinforced by means of an elevated content of silicon, including Cu, Mo and Ni additions. Thermal analyses of the melted cast iron were made and the parameters of the characteristic points on the crystallization curves were determined. The laboratory tests were performed on samples cut out of separately cast test ingots, without additional thermal treatment. An evaluation was performed of the graphite and cast iron matrix structure, as well as strength properties, hardness and thermal shock resistance.
Significantly better properties of the cast iron in the case of the experimental melts was established as compared to the non-alloy vermicular cast iron, which is the basic material used for elements working under conditions of thermal shocks. An especially advantageous operation of molybdenum and nickel (1.4% and 1.8%) on the thermal shock resistance of the cast iron was stated.
Keywords: spheroidal cast iron, Cu, Mo, Ni, structure, strength, thermal shocks,
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Artur Bobrowski, Sylwia Żymankowska-Kumon
The article presents the results of surface morphology of dust from dry dedusting of moulding sand with bentonite and mixtures of bentonite with lustrous carbon carrier using scanning electron microscopy. The study identifies the approximate chemical composition of the dust, and compares it with the composition of starting mixtures. The mixtures of bentonite with lustrous carbon carrier from different manufacturers differ in chemical composition. The process of dedusting should be carried out using properly selected operating parameters of the dedusting equipment. If the process of dedusting is carried out incorrectly, it can lead to the loss of valuable components.
Keywords: bentonite, dust, dedusting, scanning electron microscopy,
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Tomasz Szymczak, Grzegorz Gumienny, Tadeusz Pacyniak
The paper presents the results of the study of Al-Si alloys with a vanadium addition used in pressure casting. The hypoeutectic Al-Si alloy grade EN AC-46000 was applied as the initial alloy. The master alloy AlV10 was introduced into the initial alloy in the amount making it possible to obtain the vanadium content in the consecutively melted Al-Si alloys of about 0.1; 0.2; 0.3; 0,4 and 0.5 wt. %. The tests were performed on both the initial Al-Si alloy and alloys containing vanadium. The investigations included a thermal and derivative (DTA) analysis of the crystallization process, a metallographic analysis of the microstructure of casts prepared in DTA tester and pressure casts, as well as the determination of the basic mechanical properties of the pressure cast Al-Si alloy. The DTA tests showed an increase in the temperature at the beginning of the Al-Si alloy crystallization and no additional thermal effects. The metallographic examinations demonstrated a decrease of the average phase size in the microstructure of the alloy cast in the DTA tester. In the Al-Si alloys containing 0.3; 0.4 and 0.5 wt. % V, both the lamellar precipitates of eutectic silicon and of the intermetallic phases originating in the eutectics were characterized by significantly lower maximal dimensions, compared to the Al-Si alloys with lower V contents. In the microstructure of the pressure cast Al-Si alloys, which contain vanadium, "new" phases may form, which did not occur in the Al-Si alloys without V. These are probably intermetallic phases containing vanadium. The size of these precipitates increases with the increase of the vanadium content in the Al-Si alloy. The performed tests of the basic mechanical properties of the pressure cast Al-Si alloys showed the possibility of obtaining higher values of tensile strength Rm, proof stress Rp0.2 and hardness HB of the Al-Si alloys containing vanadium, compared to the Al-Si alloys without this element. The highest values: Rm = 248 MPa were obtained in the Al-Si alloy containing about 0.3% vanadium; Rp0.2 = 113 MPa - with the content of 0.1, and 0.2% and HB = 116 for the V addition of about 0.2 wt. %. As regards the Al-Si alloy without a vanadium addition, the obtained values caused an increase of Rm by 26%; Rp0.2 by 12% and HB by 7%.
Keywords: Al-Si alloy, vanadium, microstructure, mechanical properties, pressure die casting,
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Zdzisław Żółkiewicz, Andrzej Baliński, Marek Żółkiewicz
The article presents an analysis of the thermal process of polystyrene model gasification. It discusses the investigation results of the effect of temperature on the gasification kinetics of the examined polystyrene model samples. It analyzes the results of thermogravimetric tests (DTG) of copolymer PS and points to the type of chemical compounds emitted at a given temperature as a result of the thermal decomposition of expanded polystyrene.
Keywords: gasified models, polystyrene, gas emissivity,
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The article presents the results of investigations into castings made of four aluminum alloys produced with the use of squeeze casting technology.
The investigations used the following alloys: EN AW 7022 (AlZn5Mg3Cu) and its modification with a titanium addition, A201.0, EN AC-4800 (AlSi13Mg1CuNi), Al-Si-Zn according to the patent PL 158900. The alloys were used to make castings with the use of squeeze casting technology and - for comparison - die castings. Investigations were performed on the basic mechanical properties of the obtained castings.
In order to improve their mechanical properties, thermal treatment according to individually selected process parameters (depending on the alloy) was performed. The thermal treatment parameters were selected based on e.g. an analysis of the DSC diagrams. The tests proved the effectiveness of squeeze casting technology in obtaining high-strength casts made from the examined alloys.
Keywords: aluminum alloys, squeeze casting, mechanical properties, thermal treatment ,
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