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Microstructure and properties of ductile iron alloyed with silicon and molybdenum
Get PDFU ovom diplomskom radu analizirana je mikrostruktura i ispitana su vlačna
svojstva, tvrdoća, žilavost i otpornost na oksidaciju na 850 °C nodularnih ljevova legiranih
sa 4,28, 4,49 i 4,81 mas. % Si i 0,6 mas. % Mo. Pored toga, ispitana je otpornost na
oksidaciju na 850 °C feritnog nodularnog lijeva sa 2,11 mas. % Si i od feritno-perlitnog
nodularnog lijeva sa 3 mas. % Si. U analiziranim SiMo nodularnim ljevovima grafitne
čestice imaju nodularni oblik. Metalna osnova sastoji se od ferita i malog udjela
globularnog perlita koji je izlučen po granicama feritnih zrna i okružuje karbide
molibdena. S porastom udjela silicija povećava se granica razvlačenja, vlačna čvrstoća,
omjer Rp0,2/Rm i tvrdoća, a smanjuje istezanje i žilavost SiMo nodularnih ljevova jer se
povećava intenzitet očvršćivanja ferita. Karbidi molibdena negativno utječu na istezanje i
žilavost SiMo nodularnog lijeva. Analizirani SiMo nodularni ljevovi imaju znatno bolju
otpornost na oksidaciju na 850 °C od feritnog nodularnog lijeva sa 2,11 mas. % Si i od
feritno-perlitnog nodularnog lijeva sa 3 mas. % Si. Otpornost na oksidaciju nodularnog
lijeva povećava se s porastom udjela silicija.This graduate thesis analyses the microstructure, tensile properties, hardness, toughness
and oxidation resistance at 850 ° C of ductile irons alloyed with 4.28, 4.49 and 4.81 wt. %
Si and 0.6 wt. % Mo. In addition, oxidation resistance at 850 ° C of ferritic ductile iron
containing 2.11 wt. % Si and ferritic-pearlitic ductile iron containing 3 wt. % Si was also
examined. In the analysed SiMo ductile irons, the graphite particles have a nodular shape.
The metallic matrix is composed of ferrite and a small share of globular pearlite which is
present on the grain boundaries of ferrite and surrounds the molybdenum carbides. With
the increase in silicon content, yield strength, tensile strength, ratio Rp0,2/Rm and hardness
increases, and the elongation and toughness of SiMo ductile irons decreases due to increase
in intensity of strengthening of ferrite. Molybdenum carbides negatively affect elongation
and toughness of SiMo ductile irons. Analysed SiMo ductile irons have a much better
oxidation resistance at 850 ° C than the ferritic ductile iron containing 2.11 wt. % Si and
from the ferritic-pearlitic ductile iron containing 3 wt. % Si. The oxidation resistance of
ductile iron increases with increasing silicon content
Magnesium treatment methods for the ductile iron production
Get PDFDodatak sferoidizacijskih (nodularizacijskih) elemenata u rastaljeno željezo vjerojatno je najvažniji korak u proizvodnji nodularnog lijeva. Postoji mnogo elemenata koji mogu proizvesti sferični oblik grafita. U komercijalnoj praksi najčešće se upotrebljava magnezij. Dodaje se u rastaljeno željezo kao čisti magnezij ili kao magnezijeva legura. Magnezij i njegove legure imaju niske temperature isparavanja, zbog čega se njihov dodatak u rastaljeno željezo mora provesti s velikom pažnjom.
Ovaj rad daje pregled najvažnijih nodularizacijskih elemenata (magnezij, cerij i elementi rijetkih zemalja te kalcij), najčešće korištenih nodularizatora (čisti magnezij, legure nikal-magnezij te ferosilicij-magnezij legure) i postupaka obrade magnezijem koji su se dokazali kao komercijalno najuspješniji (postupak obrade prelijevanjem nodularizatora u otvorenom loncu, „Sandwich“ postupak obrade u otvorenom loncu, postupak obrade u loncu s poklopcem, postupak obrade u loncu uz propuhivanje inertnim plinom kroz porozni čep, postupak obrade uranjanjem nodularizatora, postupak obrade punjenom žicom, postupak obrade u konvertoru, postupak obrade u kalupu i postupak obrade protjecanjem).The addition of spheroidizing (nodularizing) elements to molten iron is probably the most important step in the production of ductile iron. There are a lot of elements that are capable to produce spheroidal form of graphite. In commercial practice, magnesium is most
commonly used. It is added to molten iron as pure magnesium or magnesium alloy. Magnesium and its alloys have low vaporization temperatures and, consequently, their addition to molten iron must be done with extreme care.
This paper gives a review of the most important nodularizing elements (magnesium, cerium and other rare earth elements and calcium), the most commonly used nodularizers (pure magnesium, nickel-magnesium alloys and magnesium-ferrosilicon alloys) and magnesium treatment methods that have proven to be the most commercially successful (open ladle pour-over process, sandwich open ladle treatment, tundish cover treatment, porous plug process, plunging method, cored wire treatment, converter method, in-mould treatment and flow-through process)
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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