Metallurgy and Foundry Engineering
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ISSN 1230-2325
e-ISSN: 2300-8377
Issue Date
2014
Volume
Vol. 40
Number
No. 1
Description
Journal Volume
Metallurgy and Foundry Engineering
Vol. 40 (2014)
Projects
Pages
Articles
Biodegradation of a new polymer binder based on modified starch in a water environment
(2014) Kaczmarska, Karolina; Grabowska, Beata
In this study, the results of biodegradability of a new polymeric binder consisting of modified starch – Polvitex Z (by Xenon) in a water solution are presented. Biodegradation tests were conducted in accordance with the Zahn–Wellens method, which is intended to denote the susceptibility to biodegradation by microorganisms (in high concentrations during the static test) of the non-volatile, watersoluble organic compounds. Observations of the decomposition process were carried out through regular, daily or at certain time intervals by measurement the Chemical Oxygen Demand (COD) and level of biodegradability (RT) in the prepared samples during the test. The study showed that the starch binder is fully biodegradable material in an aqueous medium.
Electrochemical behavior of tellurium in acidic nitrate solutions
(2014) Rudnik, Ewa; Biskup, Przemysław
Electrochemistry of tellurium stationary electrode was studied in acidic nitrate solutions with pH 1.5 – 3.0. Cyclic voltammetry indicated that two products were formed at potentials above 300 mV (SCE): soluble $HTeO_{2}^{+}$ (500 mV) and sparingly soluble $H_{2}TeO_{3}$ (650 mV), but the former seemed to be an intermediate product for $TeO_{2}$ precipitation on the electrode surface. Formation of the solid products as porous layers was almost undisturbed and no electrode passivation was observed. $H_{2}TeO_{3}$ and $TeO_{2}$ dissolved to $HTeO_{2}^{+}$ under acidic electrolyte, but this process was hindered by pH increase. Cathodic polarization of tellurium electrode below -800 mV was accompanied by evolution of $H_{2}Te$, which was then oxidized at the potentials approx. -700 mV. $H_{2}Te$ generated in the electrochemical reaction decomposed to elemental tellurium as black powdery precipitates in the bulk of the solution and a bright film drifting on the electrolyte surface.
Influence of annealing conditions on the properties and microstructure of steel composites
(2014) Sulima, Iwona; Hyjek, Paweł; Tokarski, Tomasz
Samples made of AISI 316L stainless steel reinforced with 8 vol.% TiB2 particles were prepared using the high pressure-high temperature (HP-HT) method. Next, the composites were annealed at a temperature of 1200°C for different holding times. The influence of the annealing temperature and time on the properties and microstructure of AISI316L+8% vol.TiB2 composites was investigated. The structural studies showed the formation of phases containing chromium, molybdenum and boron.
Amorphization and liquid state separation in $Ni_{80-2x}Cu_{x}Fe_{x}P_{20}$ alloys
(2014) Ziewiec, Krzysztof; Prusik, Krystian; Różycka, Mirosława
The aim of the work is to study the ability and potential of glass formation in Ni-Fe-Cu-P alloys. A series of alloys were produced in arc furnace (i.e. $Ni_{70}Fe_{5}Cu_{5}Pe_{20}, Ni_{60}Fe_{10}Cu_{10}P_{20}, Ni_{50}Fe_{15}Cu_{15}P_{20}, Ni_{40}Fe_{20}Cu_{20}P_{20}, Ni_{30}Fe_{25}Cu_{25}P_{20}, Ni_{20}Fe_{30}Cu_{30}P_{20}$). The primary microstructure of the ingots was studied. The ribbons in as-melt-spun state were characterized by X-ray diffraction (XRD). The $Ni_{70}Fe_{5}Cu_{5}P_{5}, Ni_{60}Fe_{10}Cu_{10}P_{20}$ melt-spun alloys were found to be amorphous. For higher copper and iron concentrations a crystalline structure was obtained after melt spinning. This correlated with the tendency for the formation of the Fe-based phases enriched in P and Cu-based poorly alloyed phases which resulted in the formation of crystalline microstructure in melt-spun ribbons. For higher concentration of Fe and Cu, microstructures of the alloys contained constituents resultant from a tendency for separation in the liquid state. It is observed that the formation of the crystal line melt-spun ribbons is caused by the attraction of phosphorus by iron and the formation of copper-based fcc phase.