1. Solidification Behavior of Fe-6.5Si Alloy Powder for AM-SLM Processing, as Assessed by Differential Scanning CalorimetryDarja Steiner Petrovič, Črtomir Donik, Irena Paulin, Matjaž Godec, Maja Vončina, Martin Petrun, 2023, izvirni znanstveni članek Ključne besede: kalorimetrija, kisik, visoke temperature, mikrostrukture, soft magnetic alloy, differential scanning calorimetry, oxygen, high-temperature phase, microstructure, eutectics
Objavljeno v DKUM: 22.05.2024; Ogledov: 128; Prenosov: 13
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2. The influence of the morphology of iron powder particles on their compaction in an automatic dieBorivoj Šuštaršič, Matjaž Godec, Črtomir Donik, Irena Paulin, Srečko Glodež, Marko Šori, Milan Ratej, Nada Javornik, 2015, strokovni članek Opis: Fe- and steel-based powder metallurgy (P/M) products, such as steel gears, spurs, locking mechanisms, porous filters, sliding bearings and bushes, as well as other machine parts and structural elements, are mainly produced with the so-called conventional sintering technology. It is the most efficient technology for the mass production of small, complex, functional and structural parts. Therefore, it is the most convenient and popular among all of the P/M technologies. The most important end-user of sintered parts is the automotive industry. However, small, complex, sintered parts can also be frequently used in the furniture and household industries, precise mechanics, articles for recreation and sports. A fine, iron-based powder mixture or prealloyed powder is first automatically uniaxial-die compacted (ADC) into the final shape of the product with a mechanical or hydraulic press and then sintered in a protective atmosphere at approximately 1100 °C. The metal powder mixture must have the appropriate engineering properties given by the chemistry and particle morphology, enabling a fast and reliable die-compaction process. The most important are a high tap density, a good powder flowability and a low compressibility. All this gives the green compacts an appropriate final shape with a smooth surface, a relatively high and uniform green density, as well as a green strength without internal flaws and cracks. In the case of very small two-or-more-heights products, for example, spur gears with a low module, it is very difficult to obtain a uniform green density at acceptable compaction pressures. Often small cracks are formed at height crossings and big differences in the green density appear in smaller or thinner regions. In the frame of our investigation we analysed the influence of the selected prealloyed commercial iron powder’s morphology and its technological properties on automatic die compaction, as well as the sintering process in the case of small two-level sintered gear dimensions of 5/40–7/10×7mm with module m = 0.5. The original iron powder was sieved and the finest powder particle fraction (< 45 µm) was compared with the original powder mixture considering ADC and sintering process. It was found that the selection of the finer powder mixture could not contribute to the improvement in the overall ADC process, as well as a better green compact. In the present paper the results of our investigations are presented and the reasons why a finer powder mixture cannot contribute much to an improvement of the conventional sintering process.
Ključne besede: Fe-based alloy powders, particles, morphology, microstructure, automatic die compaction, sintering
Objavljeno v DKUM: 27.03.2017; Ogledov: 1428; Prenosov: 373
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3. Morphological and microstructural features of Al-based alloyed powders for powder-metallurgy applicationsBorivoj Šuštaršič, Irena Paulin, Matjaž Godec, Srečko Glodež, Marko Šori, Jože Flašker, Albert Korošec, Stanislav Kores, Goran Abramović, 2014, strokovni članek Opis: Besides advanced nano steels, polymers and ceramics, recently also light metals, i.e., Al, Mg and Ti based materials, have been recognized as future materials for different kinds of advanced applications. Al and its alloys have an acceptable price, excellent corrosive resistance, good mechanical and other physical properties. Therefore, they are also used in the powder-metallurgy (P/M) field. The P/M technology of Al materials is very demanding and has its own specifics compared to the sintering technology of iron and steel. A relatively large quantity of Al-based alloy powder is formed during the sand blasting of slugs and discs in the Talum Al factory, Kidričevo, Slovenia. Therefore, we analysed and investigated its practical usability for a production of advanced products using P/M technology. The formed Al-based powder was compared with the commercially available Al-based powders that are generally used for conventional sintering technology. In the first part of this paper we explain which types of Al-based powders are used for the production of sintered parts, what the required parameters are and why we considered them. Then, the results of theoretical thermodynamic analyses and investigations of the morphological and microstructural characteristics of the selected commercial Al-based powders are given, as well as their comparison with the Al powder formed during the sand blasting and its potential for P/M applications.
Ključne besede: Al-based alloy powders, morphology, microstructure, LM characterisation, SEM/EDS characterisation
Objavljeno v DKUM: 17.03.2017; Ogledov: 1603; Prenosov: 145
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4. UPRAVIČENOST GRADITVE HITRE POLNILNE POSTAJE ZA VOZILA NA ELEKTRIČNI POGONMatjaž Godec, 2017, magistrsko delo Opis: Električna vozila so hitro razvijajoča tehnologija, ki predstavljajo potencialno trajnostno alternativo tradicionalnim vozilom z motorji notranjega izgorevanja. Z uporabo električne energije namesto fosilnih goriv, ta nova vozila zahtevajo nove sisteme infrastrukture, ki predstavljajo inovativne tehnološke investicije. Skozi magistrsko delo smo v empiričnem delu s pomočjo izdelave Načrta gradbenih konstrukcij za gradnjo dveh hitrih polnilnih postaj z večobdobno (dinamično) metodo IRR ugotavljali upravičenost graditev na mikrolokaciji. Za izdelavo kalkulacije stroškov investicije smo izdelali tehnično poročilo, projektantski predračun s popisom gradbenih del in grafične priloge. Z izvedenimi analizami trga EV, cenami električne energije, števila polnjenj na polnilnicah, kalkulacijo stroškov investicije, in predpostavljenimi prihodnjimi stroški in prihodki smo z metodo interne donosnosti izračunali upravičenost graditve hitrih polnilnih postaj, kar je predstavljalo osrednji del magistrskega dela. Kljub visokimi začetnimi vložki nam izračuni prikažejo rezultate, kateri niso upravičeni samo iz ekonomskega vidika, temveč tudi iz zasebnega.
Ključne besede: gradnja, gradbeništvo, ekonomska upravičenost, IRR, električna vozila, električna mobilnost, hitra polnilna postaja, ekonomska analiza, projektni menedžment
Objavljeno v DKUM: 01.02.2017; Ogledov: 2482; Prenosov: 259
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6. Ocenjevanje ekonomičnosti projektnih rešitev poslovno-stanovanjskih objektovMatjaž Godec, 2012, delo diplomskega projekta/projektno delo Opis: Že iz naslova projektne naloge lahko sklepamo, da bomo ocenjevali ekonomičnosti projektnih rešitev dveh poslovno stanovanjskih objektov. V poglavju 1 in 2 opisujemo namen naloge in izhodišča ter predstavljamo metodo, ki jo bomo uporabljali. V poglavju 3 predstavljamo in podrobneje opisujemo posamezna objekta. V poglavju 4 na praktičnih primerih izračunamo ter predstavimo metodo ocenjevanja ekonomičnosti, ki temelji na podlagi ocene vrednosti parametrov za lokacijske pogoje in projektno tehnične zahteve. Na podlagi pridobljene dokumentacije pripravimo izbor potrebnih podatkov, ki jih bomo uporabili za določevanje parametrov. Parametre nato primerjamo ter ocenimo. Posebej ne ocenjujemo tistih parametrov, pri katerih sta oba objekta enaka. Tako dobimo končno oceno ekonomičnosti projektnih rešitev. Oceno ekonomičnosti je smiselno uporabiti v dovolj zgodnji fazi projektiranja, torej v fazi izdelave idejnih projektov. V poglavju 5 je pripravljen izračun stroškovne vrednosti objektov.
Ključne besede: Poslovno stanovanjski objekti, ocenjevanje ekonomičnosti, parametri stanovanjskega objekta, karakteristike objektov, tlorisna površina, faktorji
Objavljeno v DKUM: 26.09.2012; Ogledov: 1989; Prenosov: 170
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