This paper deals with the effects of the addition of 0.00031, 0.00064, 0.001 and 0.0042 wt.% Bi on the matrix structure of ductile iron castings consisting of 7 sections of different thicknesses (3, 12, 25, 38, 50, 75 and 100 mm) and contain low content of Si (2.11 wt.%) and pearlite promoting element (0.018 wt.% Cu, 0.0055 wt.% Sn, 0.00041 wt.% Sb, 0.098 wt.% Mn). The Bi contents of 0.00031, 0.00064 and 0.001 wt.% were not significantly affected the share of ferrite and pearlite in the section thicknesses of 12, 25, 38, 50, 75 and 100 mm compared to the casting which does not contain Bi. In all these sections the share of pearlite was increased and the share of ferrite was decreased by the addition of 0.0042 wt.% Bi. All of the above-mentioned Bi contents were resulted in the formation of iron carbides in the section thickness of 3 mm. The share of carbides increases with increasing Bi content.
Author: Štrkalj A.
EFFECT OF ANTIMONY ON AUSTENITE TRANSFORMATION AND THE METALLIC MATRIX STRUCTURE IN DIFFERENT WALL THICKNESSES OF DUCTILE IRON CASTINGS
Effects of additions of 0.0039, 0.01, 0.019 and 0.029 wt.% Sb on austenite transformation and the metallic matrix structure in the wall thicknesses of 3, 12, 25, 38, 50, 75 and 100 mm of ductile iron casting containing 2.11 wt.% Si and a low amount of Cu, Sn and Mn were analyzed in this paper. In the examined ductile iron casting without the addition of Sb, the share of pearlite in the metal matrix was decreased and the share of ferrite was increased with increasing wall thickness. The share of pearlite was low. Additions of Sb were increased the share of pearlite in all the walls. Increase of Sb content resulted in increasing the share of pearlite. Almost the same high share of pearlite in the wall thicknesses of 12, 25, 38, 50, 75 and 100 mm was obtained by addition of 0.029 wt. % Sb (varied from 96.00 to 97.61 %). The additions of 0.01, 0.019 and 0.029 wt.% Sb were resulted in a fully pearlitic metallic matrix in the wall thickness of 3 mm. Iron carbides were found in the wall thickness of 3 mm when Sb was added.
In this paper, in order to dimension the position and the number of vertical reinforcement, several numerical linear static simulations of bending circular manhole cover of ductile cast iron (grade EN-GJS-500-7) with 600 mm diameter are performed. The analysis of displacement and stress using the finite element method in the software package Autodesk Simulation Mechanical were conducted. Verification of numerical results for the solution of thin circular plate was performed with analytical bending solutions. After checking the numerical procedure on the thin circular plate, two circular vertical reinforcements were added on the underside: internal and external. Numerical simulations investigated the influence of the inner circular reinforcement position on the strength of the circular manhole cover, while equivalent stresses followed by energy theory of strength (von Mises) were monitored. Since maximal equivalent stresses remain on the plate by varying the position of the inner circular reinforcement, simulations with added radial reinforcements are performed. Finally, by optimizing the number of radial reinforcements, the optimum plate design is chosen.
Possibility of using waste mold sand for removal of acetic acid from the aqueous solution was studied in this article. Green sand can be used several times in mold making. When the properties of green sand are not suitable for further use, it becomes waste. Waste mold sand was used in this article as an adsorbent for the removal of acetic acid from the aqueous solution. During the adsorption process, the influence of the amount of the adsorbent and contact time adsorbent/adsorbate (waste mold sand/acetic acid) on the capacity of the adsorption process was monitored. Amount of waste mold sand was varied from 25 to 125 g. Contact times were as follows: 15, 30 and 60 minutes. The obtained results indicate that the adsorption of acetic acid on the waste mold sand occurred at all used combinations of these parameters. However, for all used contact times, the greatest adsorption capacity is achieved when the ratio of waste mold sand/acetic acid was 25 g/100 mL. For all the used amount of adsorbent, the highest adsorption capacity, i.e. dynamic equilibrium was achieved very quickly, after 15 minutes. The obtained results are in accordance with the chemical composition of the waste mold sand.
This article presents the application of non-hazardous waste molding sand from gray cast iron foundry as an inexpensive adsorbent for removal of Zn(II) and Cu(II) ions from aqueous solutions. The experiments were performed at room temperature using a multi solution (Zn + Cu) with concentration was 100 mg/l. The process of removal of Zn(II) and Cu(II) ions was monitored at different contact times of waste molding sand and metal ions. The experimental data were processed by two different kinetic theories. The pseudo-first-order and pseudo- second-order models were used for modeling the kinetic rates.
Obtained results show that the waste molding sand has significant potential for the removal of Zn(II) and Cu(II) ions from aqueous solutions. Research shows that the removal of Cu(II) ions was better than removal of Zn (II) ions. It is possible to conclude that the mutual competition of Cu(II) and Zn(II) ions for adsorption sites affect the intensity of their removal.
For many years casting alloys are widely used in dental applications. Among them, titanium and its alloys reveal the best properties for this purpose. However, the casting is difficult but it may be improved by alloying. This research deals with titanium-based alloys with zirconium additions. Investigated alloys were prepared by melting and casting in an electro-arc furnace under argon atmosphere. In order to identify the phases present in alloys, structural analysis was performed by X-ray diffraction method. It was showed two-phases microstructure of alloys. Further, zirconium addition in higher percentage contributes to formation of the beta phase of titanium which possesses more adequate properties then alpha titanium. Microstructural observations by scanning electron microscopy and energy-dispersive spectrometry showed that phases have similar chemical composition. Measured Vickers hardness values were lower than for pure titanium and are acceptable for dental applications.