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Number of results: 6
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Abstract

Recyclability is one of the great features of aluminium and its alloys. However, it has been typically considered that the secondary aluminium quality is low and bad. This is only because aluminium is so sensitive to turbulence. Uncontrolled transfer and handling of the liquid aluminium results in formation of double oxide defects known as bifilms. Bifilms are detrimental defects. They form porosity and deteriorate the properties. The detection and quantification of bifilms in liquid aluminium can be carried out by bifilm index measured in millimetres as an indication of melt cleanliness using Reduced Pressure Test (RPT). In this work, recycling efficiency and quality change of A356 alloy with various Ti additions have been investigated. The charge was recycled three times and change in bifilm index and bifilm number was evaluated. It was found that when high amount of Ti grain refiner was added, the melt quality was increased due to sedimentation of bifilms with Ti. When low amount of Ti is added, the melt quality was degraded.

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Authors and Affiliations

O. Gursoy
E. Erzi
K. Tur
D. Dispinar
ORCID: ORCID
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Abstract

The paper presents results of a study concerning an AlSi7Mg alloy and the effect of subjecting the liquid metal to four different processes: conventional refining with hexachloroethane; the same refining followed by modification with titanium, boron, and sodium; refining by purging with argon carried out in parallel with modification with titanium and boron salts and strontium; and parallel refining with argon and modification with titanium, boron, and sodium salts. The effect of these four processes on compactness of the material, parameters of microstructure, and fatigue strength of AlSi7Mg alloy after heat treatment. It has been found that the highest compactness (the lowest porosity ratio value) and the most favorable values of the examined parameters of microstructure were demonstrated by the alloy obtained with the use of the process including parallel purging with argon and modification with salts of titanium, boron, and sodium. It has been found that in the fatigue cracking process observed in all the four variants of the liquid metal treatment, the crucial role in initiation of fatigue cracks was played by porosity. Application of the process consisting in refining by purging with argon parallel to modification with Ti, B, and Na salts allowed to refine the microstructure and reduce significantly porosity of the alloy extending thus the time of initiation and propagation of fatigue cracks. The ultimate effect consisted in a distinct increase of the fatigue limit value.

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Authors and Affiliations

M. Tupaj
ORCID: ORCID
A.W. Orłowicz
ORCID: ORCID
A. Trytek
ORCID: ORCID
Marek Mróz
ORCID: ORCID
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Abstract

The paper presents an experimental confirmation of the fact that if a three-dimensional volume does not contain spherical particles with particular size, the Probability Density Function (PDF1) of half-chord lengths has proportional ranges. This fact has been deduced in work [1] during the derivation process of the Probability Density Function (PDF3) that maps the particle radii on the basis of data (PDF1) collected from flat cross-sections. The experiment has been executed virtually by using a simple computer program written in the C++11 language. The computer generation of particles allowed imposing various kinds of known PDF3 and the ranges in which the particles could not be created. Next, the virtual nodules have been used to produce sets of chords that served as input data to create histograms that approximated the continuous PDF1. Having such histograms, it was possible to reveal proportional scopes of the PDF1. The proportional dependencies occurred in the same ranges where the nodules had not been generated.
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Bibliography

[1] Gurgul, D., Burbelko, A. & Wiktor T. (2021). Derivation of equation for a size distribution of spherical particles in non-transparent materials. Journal of Casting & Materials Engineering. 5(4), 53-60.
[2] Wicksell, S.D. (1925). The corpuscle problem: mathematical study of a biometric problem. Biometric. 17 (1/2), 84-89.
[3] Sheil, E. (1935). Statistische gefügeuntersuchungen I. Zeitschrift für Metallkunde. 27 (9), 199-208.
[4] Schwartz, H.A. (1934). The metallographic determination of the sze distribution of temper carbon nodules. Metals and Alloys. 5, 139-140.
[5] Saltykov, S.A. (1967). The determination of the size distribution of particles in an opaque material from the measurement of the size distribution of their section. in the second international congress for stereology, Chicago, 8-13 April 1967. Berlin–Heidelberg–New York, Springer Verlag.
[6] Cahn, J.W. & Fulmann, R.L. (1956) On the use of lineal analysis for obtaining particle size distributions in opaque samples. Transactions, American Institute of Mining, Metallurgical and Petroleum Engineers. 206, 177-187. [7] Lord, G.W. & Willis, T.F. (1951). Calculation of air bubble size distribution from results of a rosiwal traverse of aerated concrete. ASTM Bulletin. 177, 177-187.
[8] Spektor, A.G. (1950). Analysis of distribution of spherical particles in non-transparent structures. Zavodsk. Lab. 16, 173-177.
[9] https://www.cplusplus.com (date of access 06.06.2021).
[10] Burbelko, A., Gurgul, D., Guzik, E. & Kapturkiewicz, W. (2018). Stereological analysis of the statistical distribution of the size of graphite nodules in DI. Materials Science Forum. 925, 98-103.
[11] Fras, E., Burbelko, A.A. & Lopez, H.F. (1996). Secondary nucleation of eutectic graphite grains. Transactions of the American Foundrymen Society. 104, 1-4.

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Authors and Affiliations

D. Gurgul
1

  1. AGH University of Science and Technology, Kraków, Poland
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Abstract

For quality grey cast iron production, the challenging issues are to avoid cementite structure and obtain the desired graphite morphology with proper matrix as well as hardness. The objective of the present research is to find out the right combination of preconditioner and inoculant that may help to overcome the challenges. In this work, sulphur content is kept low (0.01%). Two preconditioners namely metallurgical SiC and zirconium bearing FeSi with two types of inoculant are individually used to make four combinations of sample and for each case metal is poured into the green sand mould. Finally Brinell hardness and graphite morphology is observed in the thickest and thinnest portions of the castings. Metallurgical SiC with barium bearing inoculant gives better graphite morphology and hardness than strontium bearing inoculant, on the other hand zirconium bearing FeSi gives more satisfying result than SiC with every type of inoculant. Among all of the combinations Zr bearing preconditioner with Ba bearing inoculant gives good graphite morphology with best mechanical properties in both thickest and thinnest portions of the casting.

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Authors and Affiliations

Md. Sojib S. Hossain
A.K.M. Bazlur B. Rashid
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Abstract

The article reports on the Etymological Dictionary of the Old Church Slavonic Language, which was completed at the end of 2022. It is the first extensive scientific etymological vocabulary of Old Church Slavonic, consisting of a total of 21 volumes, of which 19 volumes contain entries (there are 2483 entries on 1164 pages). The last two volumes are registers of all words listed in the dictionary.
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Authors and Affiliations

Ilona Janyšková
1
ORCID: ORCID

  1. Etymologické oddělení Ústavu pro jazyk český, Akademie věd České republiky, Brno
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Abstract

Increasing numbers of implanted cardiovascular electronic devices, results in a need for lead extractions, which has increased to an annual volume of over 10,000 worldwide. We present a cadaveric dissection body with a single chamber pacemaker implanted 5y before death.

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Authors and Affiliations

Marcin Kuniewicz
Jerzy Andrzej Walocha
Kinga Budnicka
Małgorzata Mazur
Ewa Walocha
Michał Jurczyk

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