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Effect of alloying elements on the microstructure and hardness of titanium
No full textU ovom radu proučavan je utjecaj dodatka legirnih elemenata na mikrostrukuru i tvrdoću titana. Eksperimentalni uzorci uključuju titan, te legure Ti 90Zr10, Ti80Zr20, Ti80Zr10Nb10 i Ti70Zr10Nb20, a pripremljeni su taljenjem i lijevanjem u laboratorijskoj elektrolučnoj peći u zaštitnoj atmosferi argona. Prije ispitivanja uzorci su metalografski pripremljeni ulaganjem u karbonsku masu, te su brušeni i polirani, a nakon ispitivanja tvrdoće Vickersovom metodom provedeno je nagrizanje. Mikrostruktura je proučavana na svjetlosnom mikroskopu. Kvantitativnom metalografskom analizom određeni su broj i veličina zrna. Detaljna analiza mikrostrukture provedena je pomoću skenirajućeg elektronskog mikroskopa s energetskodisperzijskim spektrometrom, te analizom pomoću difrakcije rentgenskih zraka. Parametri elementarne ćelije prisutnih faza izračunati su pomoću odgovarajućeg računalnog programa. Analiza mikrostrukture je pokazala da nelegirani titan ima α strukturu, dok se dodatkom veće količine cirkonija ona mijenja u dvofaznu. Dodatkom niobija postignuta je jednofazna β struktura. Mjerenja tvrdoće su pokazala da nelegirani titan ima puno niţu tvrdoću od ispitivanih legura, što ukazuje da mu dodatak ovih legirnih elementa značajno povećava tvrdoću. Prema dobivenim rezultatima, eksperimentalne legure imaju potencijal za daljnja istraţivanja u svrhu biomedicinske primjene.In this work effect of alloying elements addition on the microstructure and hardness of titanium was investigated. Experimental samples including titanium, Ti90Zr10, Ti80Zr20, Ti80Zr10Nb10 and Ti70Zr10Nb20 alloys were prepared by melting and casting in laboratory arc furnace in argon atmosphere. Samples were mounted in conductive resin and metallographically prepared by grinding and polishing. After testing of ardness by Vickers method, all samples were etched for microscopic examinations. Microstructure was observed
by light microscope. Number of grains and their average size were determined by quantitative metallography. Microstructure in detail was investigated by scanning electron microscope with energy dispersive spectrometer, and X-ray diffraction analysis as well. Cell parameters of present phases were determined by corresponding computer program. Microstructural
analysis showed α phase structure of unalloyed titanium, which is partially transformed into β phase by higher zirconium addition resulting in two-phases microstructure. Addition of niobium single β phase was obtained. Hardness measurements revealed that unalloyed titanium exibits much lower hardness values the experimental alloys indicating that alloying
elements addition significantly increases its hardness. According to obtained results experimental alloys have potential to be further investigated for biomedical purpose
Recycling of titanium and titanium-based alloys
Get PDFRecikliranje metala i njihova industrijska upotreba postupno zauzimaju vaņno mjesto u svijetu kako zbog očuvanja prirodnih resursa i sve potrebnije zańtite okolińa, tako i zbog smanjenja trońkova proizvodnje metala. Materijali na bazi titana imaju odreĎene karakteristike koje ih čine promjenjivim u različitim granama industrije, a zbog neograničenog vijeka trajanja postaju izvrstan resurs za recikliranje. Krollovim procesom, glavnim postupkom dobivanja titana, stvara se kloridni otpad (MgCl2) koji se po nastanku uklanja recikliranjem, pri čemu se dobiveni metalni magnezij i plinoviti klor primjenjuju u daljnjoj industrijskoj proizvodnji titana. Recikliranje titana i njegovih legura ima pozitivan učinak na okoliń, a za njegovo recikliranje je potrebno i manje energije. Karakteristični reciklaņni procesi za proizvodnju titana i njegovih legura su ekstrakcija te recikliranje u plazma pećima.Recycling of metals and their industrial use gradually occupy the important place in the world due to preservation of natural resources and necessary environmental protection ensurance, as well as due to reduction metal production expenses. Titanium-based materials have certain characteristics which enable theirs application in different branches of industry. Due to their unlimited lifetime (end of life - EoL) titanium materials became an excellent resource for recycling. By Kroll's process, as the main method for the titanium production, chloride waste (MgCl2) is produced. During recycling process, extraction of metallic magnesium and gaseous chlorine occurred and used in further industrial production of titanium. The recycling of titanium- based materials has a positive effect on the environment, and its recycling used less energy. Characteristic recycling processes for the production of titanium and its alloys are extraction and recycling in plasma furnaces
METALLIC MATERIALS FOR APPLICATION IN DENTISTRY
Get PDFStomatologija kao grana medicine ima značajnu ulogu u zdravlju čovjeka, a primjenom novih tehnologija održavanje oralnog zdravlja je puno učinkovitije. U tu svrhu upotrebljavaju se dentalni proizvodi, poput krunica, mostova, nadomjestaka, koji se izrađuju od različitih metalnih materijala najčešće lijevanjem ili kovanjem. Oni moraju posjedovati odgovarajuća svojstva, među kojima su najvažnija: biokompatibilnost, tvrdoća, čvrstoća. Metal kao zaseban element sa svojim svojstvima ne zadovoljava u potpunosti tražene uvjete, te se stoga postupkom legiranja dobivaju različite legure koje se mogu primjenjivati u oralnoj sredini. Najčešća podjela metalnih materijala koji se primjenjuju u stomatologiji je na: plemenite i neplemenite legure, te dentalne amalgame. Nadalje, razvojem novih tehnologija omogućeno je dobivanje novih metalnih materijala s još pogodnijim svojstvima. Tu se svakako ističu titan i legure na bazi titana kao materijali budućnosti u stomatologiji. Također, napredak u računalnoj tehnologiji rezultira bržom proizvodnjom kvalitetnijih i ekonomičnijih dentalnih metalnih proizvoda.Dentistry as a branch of medicine has an important role in the health of the human, while applying new technologies maintaining oral health is much more effective. For that purpose many dental products are used, such as crowns, bridges, implants, which are made of various metallic materials the mostly by casting or forging. They have to possess adequate properties
among which biocompatibility, hardness and strength are the most important. Metal as an individual element with its properties doesnot meet certain conditions, therefore, the process of alloying results in different alloys that may be applied in oral environment. The most common classification of metallic materials for use in dentistry divides them on: noble and
non-noble alloys and dental amalgames. Further, development of new technologies provides a new metallic materials with more adequate properties. Among them, titanium and titaniumbased alloys stand out as materials of future in dentistry. Also, progress in computer technology results in faster production of economic dental products of much more quality
The effect of waste dental metallic materials on environment
Get PDFDental medicine is a profession dedicated to promoting and enhancing oral health and well- being and therefore plays a significant role in human health. Dental practices produce many types of dental wastes, such as: heavy metals and biomedical waste, which could cause harm to the environment if it is disposed improperly. Among them, mercury, silver and lead are the most harmful for humans and the environment as well. In order to reduce the impact on the environment dentists should take all possible activities to completely avoid the production of any waste or at least try to reduce the amount of waste to a minimum. In that context, eco- friendly dentistry as a new approach to dental practice is developed. It is based on use of non-toxic products, waste reduction, energy conservation and pollution prevention. Finally, education regarding the proper management and disposal of waste from dental offices needs more attention
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
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