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2. Comprehensive analysis of different coating materials on the POM substrateTonica Bončina, Srečko Glodež, Brigita Polanec, Lara Hočuršćak, Franc Zupanič, 2023, izvirni znanstveni članek Opis: This study presents a comprehensive analysis of different coating materials on the POM substrate. Specifically, it investigated physical vapour deposition (PVD) coatings of aluminium (Al), chromium (Cr), and chromium nitride (CrN) of three various thicknesses. The deposition of Al was accomplished through a three-step process, particularly plasma activation, metallisation of Al by magnetron sputtering, and plasma polymerisation. The deposition of Cr was attained using the magnetron sputtering technique in a single step. For the deposition of CrN, a two-step process was employed. The first step involved the metallisation of Cr using magnetron sputtering, while the second step involved the vapour deposition of CrN, obtained through the reactive metallisation of Cr and nitrogen using magnetron sputtering. The focus of the research was to conduct comprehensive indentation tests to obtain the surface hardness of the analysed multilayer coatings, SEM analyses to examine surface morphology, and thorough adhesion analyses between the POM substrate and the appropriate PVD coating.
Ključne besede: POM, PVD coating, metal coating, adhesion analyses, indentation tests
Objavljeno v DKUM: 15.02.2024; Ogledov: 304; Prenosov: 47
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3. Wear Behaviour of Multilayer Al-PVD-Coated Polymer GearsTonica Bončina, Brigita Polanec, Franc Zupanič, Srečko Glodež, 2022, izvirni znanstveni članek Opis: A comprehensive experimental investigation of the wear behaviour of coated spur polymer gears made of POM is performed in this study. Three different thicknesses of aluminium (Al) coatings were investigated and deposited by the Physical Vapour Deposition (PVD) process. The Al coating was deposited in three steps: By plasma activation, metallisation of the aluminium by the magnetron sputtering process, and plasma polymerisation. The wear of the gears was tested on an in-house developed testing rig for different torques (16, 20, and 24 Nm) and a rotational speed of 1000 rpm. The duration of the experiments was set to 13 h, when the tooth thickness and, consequently, the wear of the tooth flank were recorded. The experimental results showed that the influence of metallisation with aluminium surface coatings on the wear behaviour of the analysed polymer gear is not significantly important. The results also showed that the gears with a thicker aluminium coating showed greater wear than gears with a thinner coating or even without a coating. This is probably due to the fact that the aluminium particles that started to deviate during gear operation represented the abrasive material, which led to the faster wear of the contacting surfaces of the meshing gear flanks.
Ključne besede: polymer gears, aluminium PVD coating, Physical Vapour Deposition process, multilayer coating, wear
Objavljeno v DKUM: 15.11.2022; Ogledov: 580; Prenosov: 472
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4. Metode prekrivanja informacije v slikah PNG : diplomsko deloLuka Kovačič, 2021, diplomsko delo Opis: V diplomskem delu najprej predstavimo pomembne aspekte slikovnega formata PNG,
kjer razložimo koncept prepletanja in filtre PNG. Nato se osredotočimo na metode za
prekrivanje informacije. Osredotočimo se na metode LSB, LSBMR, PVD, PPV in EMD.
Metode implementiramo in jih nato med seboj primerjamo.
Ključne besede: steganografija, prostorska domena, rastrske slike, metode LSB, LSBMR, PVD, PPV, EMD
Objavljeno v DKUM: 18.10.2021; Ogledov: 717; Prenosov: 69
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5. RAZVOJ NOVIH KOVINSKIH MATRIC Z IONSKO IN KOVALENTNO VEZANIMI TRDNIMI SNOVMIMaja Pori, 2013, diplomsko delo Opis: Obraba je glavni krivec za potrato materialov in izgubo njihovih mehanskih lastnosti. Vsako zmanjšanje obrabe materiala lahko vodi do velikih prihrankov. Glavna motivacija te diplomske naloge je razvoj novih kovinskih kompozitov na osnovi Fe. Ti kompoziti so sestavljeni iz kovinske matrice z fino razpršenimi trdimi delci v njeni mikrostrukturi. Cene zlitin na osnovi Ni and Co so visoke, prav tako pa imajo te zlitine toksičen in kancerogen efekt. Trde zlitine na osnovi Fe predstavljajo ekonomsko in ekološko alternativo. Potreba po optimizaciji se lahko pojavi tudi z ozirom na trde delce, ki so vstavljeni v kovinsko matrico. Kot spojina za trdi delec je bil uporabljen kovinsko vezan WC. Zaloge le tega na tržišču so omejene, sočasno pa naraščajo cene te spojine na tržišču. Poleg cene kot pomanjkljivost lahko omenimo raztopitev WC v materialih, ki temeljijo na Fe. V želji, da bi se izognili visokim cenam in omejili raztopitev WC, predstavljajo novi trdi ionsko vezani (SiO2, AlZrO) in kovalentno vezani (SiC) trdi delci zanimivo alternativo. Vzroke, zakaj ti trdi delci niso bili uporabljeni že prej, lahko pripisujemo njihovim lastnostim vezave, ki omejuje vezavo teh trdih delcev v kovinsko matrico. Za izboljšanje njihove vezave je na površino teh delcev nanesena ovojnica s PVD procesom. V primeru ionsko vezanih delcev ta ovojnica spodbuja vezavo delcev v kovinsko matrico, v primeru kovalentno vezanih delcev pa nanesena ovojnica služi kot ovira za raztopitev trdih delcev v materialih, ki temeljijo na Fe. Kovinski kompoziti z vezanimi trdimi delci so proizvedeni s procesom InduClad. V ospredju raziskav so stičišča med trdimi delci in ovojnico, ter ovojnico in kovinsko matrico. Raziskave so bile opravljene z elektronskim in optičnim mikroskopom. Nadalje je raziskana mikrostruktura in obraba proti trdim abrazivom kovinskih kompozitov. Za primerjavo med mikrostrukturo in obrabo delcev so bili vzorci raziskani po standardu ASTM G65. Rezultati so pokazali, da nanos ovojnice na ionsko vezane trde delce (SiO2 , AlZrO) izboljša vezavo delcev v kovinsko matrico in posledično zmanjša obrabo kovinskih kompozitov. Nanos ovojnice na kovalentno vezane delce skoraj popolnoma prepreči raztopitev delcev v kovinskih matricah.
Ključne besede: Obraba, zlitine na osnovi Fe, PVD proces, InduClad proces, WC, AlZrO, SiO2, SiC
Objavljeno v DKUM: 16.08.2017; Ogledov: 882; Prenosov: 133
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6. Morphology and corrosion properties PVD Cr-N coatings deposited on aluminium alloysDarja Kek-Merl, Ingrid Milošev, Peter Panjan, Franc Zupanič, 2011, izvirni znanstveni članek Opis: The attempt to find an alternative coating for corrosion protection of Al- alloys was made. PVD coatings are one of the possible alternatives for replacement of ecological unfriendly chromate coatings. Chromium-nitride (Cr-N) and Ni/Cr-N coatings were sputtered on aluminium substrates (AA7075 and cladded AA2024). Surface and sub-surface characterizations were performed by AFM and SEM. Special attention was given to defects incorporated into coatings, since they play important role in the corrosion protection of the coating/substrate systems. The cross-sections through the typical defects were performed by ion beam milling incorporated into the SEM. The Vickers hardness of the Cr-N with and without layer of Ni on both substrates was determined. After the coatings deposition, the values of Vickers hardness (10 mN load) increase for 10 to 100-fold compared to the substrates. The corrosion behaviour of Cr-N and Ni/Cr-N thin films was investigated in near neutral 0.1 M solution of NaCl using potentiodynamics electrochemical measurement. Cr-N and Ni/Cr-N coatings shift the corrosion potentials to more positive values. The best corrosion resistance among the tested coating/substrate systems were found for Ni/Cr-N on AA7075 substrate.
Ključne besede: Al-alloys, corrosion properties, CrN films, FIB, PVD coatings
Objavljeno v DKUM: 17.03.2017; Ogledov: 1359; Prenosov: 121
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7. Characterization of defects in PVD TiAlN hard coatingsPeter Gselman, Tonica Bončina, Franc Zupanič, Peter Panjan, Darja Kek-Merl, Miha Čekada, 2012, izvirni znanstveni članek Opis: PVD hard coatings are continuously gaining their importance in different fields of applications. In industrial use, they are often exposed to corrosive environments. Hard coatings possess inherently good corrosion resistance, but the substrate-hard coating systems may suffer from a severe corrosion attack due to the defects (craters, pin holes) in the coatings. On the sites, where defects extend through the coating, pitting corrosion can take place. These sites are drawbacks in the applications of hard coating. A PVD TiAlN hard coating was prepared on cold-work, tool-steel (AISI D2) substrates by sputtering using unbalanced magnetron sources. The growth defects incorporated into the coating were studied after the deposition and corrosion experiments. We used two methods: (1) scanning electron microscopy (SEM) for general overview of the coating topography and 2D-characterization of defects, and (2) scanning electron microscopy with a focused ion beam (SEM-FIB) for making serial cross-sections through the selected defects in order to provide images for a 3D-reconstruction of defects. In this work we tried to investigate the formation of a defect at a specific location and findout whether the selected defect causes pitting corrosion.
Ključne besede: trde prevleke, PVD prevleke, defekti, jamičasta korozija, mikrostruktura, PVD hard coating, defect, pitting corrosion, microstructure
Objavljeno v DKUM: 10.07.2015; Ogledov: 1437; Prenosov: 107
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8. DEFEKTI PVD-PREVLEK IN NJIHOV VPLIV NA FIZIKALNO-KEMIJSKE LASTNOSTI SISTEMA PREVLEKA/PODLAGAPeter Gselman, 2014, doktorska disertacija Opis: Trde zaščitne prevleke, izdelane po postopku fizikalnega nanašanja iz parne faze (PVD – angl. physical vapor deposition), so se izkazale za enega izmed najučinkovitejših načinov povečanja produktivnosti odrezovalnih postopkov, vendar njihov potencial še ni popolnoma izkoriščen. Med nanašanjem v njih nastajajo defekti, ki poslabšajo oprijemljivost prevlek na podlago, zmanjšujejo korozijsko obstojnost itd.
Kakovost trdih prevlek izboljšamo, če zmanjšamo koncentracijo defektov. To lahko naredimo le, če poznamo mehanizme njihovega nastanka. V disertaciji so opisani mehanizmi nastanka defektov v posameznih stopnjah priprave prevlek in njihov vpliv na fizikalno-kemijske lastnosti sistema prevleka/podlaga.
Defekti so bili analizirani v nanoplastni prevleki TiAlN/CrN, ki je bila nanesena na štiri vrste jeklenih podlag (ASP30, M2, D2 in 316L) v naprševalniku s štirimi neuravnoteženimi magnetronskimi izviri. Za preučevanje izvorov, mehanizma nastanka in vpliva defektov PVD-prevlek na fizikalno-kemijske lastnosti sistema prevleka/podlaga so bile uporabljene naslednje tehnike: optični mikroskop (OM), mikroskop na atomsko silo (AFM), vrstični elektronski mikroskop (SEM), fokusiran ionski curek (FIB), presevni elektronski mikroskop (TEM), energijsko-disperzijska spektroskopija (EDS), tribometer, 3D-profilometer in 3D-rekonstrucija iz SEM-posnetkov.
Ugotovljeno je bilo, da defekti v prevleki nastanejo predvsem zaradi geometrijskega senčenja, ki ga povzročajo topografske nepravilnosti na površini podlag, delci, ki so po čiščenju ostali na površini, ter delci, ki prispejo na površino podlag med pripravo prevlek (segrevanje, ionsko jedkanje, naprševanje). Kali defektov predstavljajo tudi sulfidni in oksidni nekovinski vključki. Na mestih sulfidnih vključkov v prevleki nastajajo kraterji in pore ne glede na vrsto jeklenih podlag in način jedkanja. Na intenzivno jedkanih oksidnih vključkih v prevleki nastanejo pore, medtem ko na blago jedkanih oksidnih vključkih prevleka raste nemoteno.
Najpogostejše topografske nepravilnosti na površini trdih prevlek so nodularni defekti. Ti imajo tudi največji vpliv na povečanje površinske hrapavosti prevleke. Ugotovljeno je bilo tudi, da med tribološkim testom (angl. pin-on-disk) nastanejo prve poškodbe prevleke na mestih nodularnih defektov. Ti defekti so v začetni fazi tribološkega testa glavni vir abrazivnih delcev, ki povzročijo začetek obrabe prevleke. Izkazalo se je, da korozijsko obstojnost sistema prevleka/podlaga poslabšajo le tisti defekti, ki omogočajo elektrolitu prosto pot do podlage.
Ključne besede: defekti, PVD-prevleka, jamičasta korozija, nekovinski vključki v jeklu
Objavljeno v DKUM: 30.10.2014; Ogledov: 3177; Prenosov: 473
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