1. Monoid algebras and graph productsWilfried Imrich, Igor Klep, Daniel Smertnig, 2025, izvirni znanstveni članek Povzetek: In this note, we extend results about unique nth roots and cancellation of finite disconnected graphs with respect to the Cartesian, the strong and the direct product, to the rooted hierarchical products, and to a modified lexicographic product. We show that these results also hold for graphs with countably many finite connected components, as long as every connected component appears only finitely often (up to isomorphism). The proofs are via monoid algebras and generalized power series rings.
Ključne besede: graph products, monoid algebras, power series rings, uniqueness of roots, cancellation property
Objavljeno v DiRROS: 29.04.2025; Ogledov: 29; Prenosov: 7
 Celotno besedilo (443,12 KB)
Gradivo ima več datotek! Več... |
2. The effect of pore sealing in a multilayer ▫Si–O–Zr/Al_2O_3▫ coating designed to protect aluminium from corrosionPeter Rodič, Barbara Kapun, Ingrid Milošev, 2023, izvirni znanstveni članek Povzetek: This study deals with the combination of two corrosion protection strategies for aluminium: barrier protection (provided by a 3.8 μm thick hybrid sol–gel coating) and aluminium pore sealing via the use of a 100 nm thick layer of aluminium oxide. A Si–O–Zr hybrid sol–gel coating (TMZ) was synthesised by combining two separately prepared sols (i) tetraethyl orthosilicate and 3-methacryloxypropyl trimethoxysilane and (ii) zirconium(IV) n-propoxide chelated with methacrylic acid. The synthesis of the Si–O–Zr hybrid sol–gel was evaluated at various stages using real-time infrared spectroscopy. A 100 nm thick Al2O3 film was prepared via thermal atomic layer deposition at 160 °C using trimethyl aluminium and water as precursors. The coating and film properties were assessed via focused ion beam/scanning electron microscopy coupled with energy-dispersive X-ray spectrometry. Sealing with the Al2O3 film did not affect the microstructure and composition of the underlying sol–gel coating. The coating’s corrosion performance in 0.1 M NaCl solution was evaluated using electrochemical impedance spectroscopy. Compared to individual coatings, the multilayer TMZ/Al2O3 coating ensured prolonged (more than three weeks) durable corrosion protection for the aluminium. The impedance magnitude increased by two orders compared to the uncoated substrate (|Z|10 mHz from 16 kΩ cm2 to almost 830 MΩ cm2). Thus, the pore sealing of the sol–gel coating using an ALD alumina film produced a protective multilayer coating system, with |Z|10 mHz remaining above 5 MΩ cm2 after four weeks in NaCl solution.
Ključne besede: aluminum, corrosion, hybrid sol-gel, atomic layer deposition, pore sealing
Objavljeno v DiRROS: 29.04.2025; Ogledov: 17; Prenosov: 8
Celotno besedilo (11,89 MB)
Gradivo ima več datotek! Več... |
3. Inhibition of the localised corrosion of AA2024 in chloride solution by 2-mercaptobenzimidazole and octylphosphonic acidDževad Kozlica, Javier Izquierdo Pérez, Ricardo M. Souto Suàrez, Ingrid Milošev, 2023, izvirni znanstveni članek Povzetek: High strength-to-weight ratio aluminium alloy (AA) 2024-T3 is an indispensable material in many transport industries like aerospace as it increases loading capacity and reduces energy consumption1 . Although nano-to-micro scale intermetallic particles (IMPs) are the main contributors to mechanical properties, they are also the main culprits for the most insidious site-specific local degradation events at the surface of AA20242 . IMPs such as Al2CuMg and Al2Cu tend to dealloy at the open circuit potential (OCP), leading to the creation of catalytic high surface area copper enriched intermetallic remnants and associated copper redistribution (i.e., copper replating) on the alloy surface3–8 . Both of these processes significantly support increased oxygen reduction reaction (ORR) rates leading to increased local alkalinity due to the production of OH− ions, causing aluminium matrix dissolution in the form of localised trenching around the IMPs and pit initiation and growth9–11. Therefore, an effective way to increase the corrosion resistance of AA2024 is to suppress the dissolution of IMPs. One aspect of current research in corrosion inhibition has focused on organic molecules with heteroatoms, such as nitrogen, oxygen, sulphur and phosphorus, that contain a lone pair of electrons and/ or delocalised π electrons due to the presence of multiple bonds or aromatic rings12.
Objavljeno v DiRROS: 29.04.2025; Ogledov: 26; Prenosov: 8
Celotno besedilo (11,38 MB) |
4. Challenges for the corrosion science, engineering, and technology community as a consequence of growing demand and consumption of materials : a sustainability issueIngrid Milošev, John R. Scully, 2023, izvirni znanstveni članek Povzetek: This perspective is intended to bring awareness to the corrosion community that the growing demand for engineering metallic materials required for our increasingly technological society is unsustainable. Current strategies important for materials science and especially the corrosion community are presented. First, the consumption of metals is reviewed, and the global supplies and demands of metals are discussed given different scenarios, including models of global societal development. It is pointed out that expected future consumption rates place pressure on the availability of specific elements used regularly throughout the world, with nearly every element in the periodic table now utilized in production of new technological devices. The consumption pushes the mining and production of metals to levels that should be counterbalanced with novel engineering and technological methods that incorporate strategies for metal sustainability. Standard approaches such as “make-use-dispose” must gradually be transformed into a circular economy paradigm embracing the “reduce-reuse-recycle” approach. Although recycling can bolster the engineered material supply, the growing demands require additional actions to significantly preserve natural resources and prolong metal sustainability. Our views on the abilities of the corrosion community to contribute to the concept of a circular sustainable economy are introduced. Maintenance strategies and corrosion management control may not be sufficient and need to be complemented with existing or emerging new technologies such as additive manufacturing, inverse engineering design, and solvometallurgy in combination with integrative design, modeling, and machine learning approaches. The corrosion community can impact the end-of-life of components and infrastructure at different levels, starting from mining through design, production, use, reuse, and recycling. Each process step is discussed, seeking possible solutions to preserve the metal resources by, for example, achieving more efficient and high-yield mining, designing and modeling new materials, increasing production efficiency, introducing light-weighting and smart materials, as well as developing more efficient recovery, recycling, and separation.
Ključne besede: circular economy, metal recycling, solvometallurgy, sustainability
Objavljeno v DiRROS: 29.04.2025; Ogledov: 29; Prenosov: 11
Celotno besedilo (727,22 KB)
Gradivo ima več datotek! Več... |
5. DFT study of Cl− ingress into organic self-assembled monolayers on aluminumFatah Chiter, Dominique Costa, Matic Poberžnik, Ingrid Milošev, Philippe Marcus, Anton Kokalj, 2023, izvirni znanstveni članek Povzetek: We address the mechanism by which organic layers on aluminum substrate hinder the penetration of Cl− toward the metal substrate. Localized corrosion by chlorides on Al and its alloys is a major problem, and organic molecules that form self-assembled monolayers on metal substrates may provide efficient corrosion protection. In one of our previous works, we established experimentally that long-chain n-alkyl carboxylic acids form protective layers against Cl− corrosion on Al substrates. In a different work, we identified, using implicit models of the organic layer and metal substrate, two essential effects by which organic layers hinder the penetration of Cl− ions toward the metal substrate. The first effect is due to the inferior solvation of ions in the organic layer compared to that in an aqueous solvent. The second effect is due to the electric field at the electrochemical interface, and the extent to which it affects the penetration of Cl− depends on the electrode potential and the thickness of the organic layer. Both effects are related to a low dielectric constant of the self-assembled monolayer. In the present study, we continue our investigation and explicitly model the organic monolayer and Al substrate using density-functional-theory calculations. To this end, we consider organic monolayers consisting of either dodecanoic- or hexanoic-acid molecules. Current calculations confirm the findings of the simplified implicit models, i.e. the energy barrier for the Cl− penetration increases with the thickness of the organic monolayer and with Cl− concentration in the monolayer. Furthermore, we propose a new mechanism by which Cl− penetrates the organic monolayer. Due to the considerably inferior solvation of Cl− in the organic layer compared to that in water, calculations suggest that it is energetically easier to locally “open” the organic monolayer by creating a hole large enough to accommodate water molecules and Cl−. The presence of water molecules ensures a stronger Cl− solvation and a better electrostatic screening between anions. While the energy barrier for the Cl− penetration via the local “opening” mechanism is suggested to be smaller than for the penetration of Cl− into dense homogeneous organic monolayer, it is still significant enough to pose a considerable kinetic barrier for the penetration of Cl− from the aqueous solution into the organic monolayer at room temperature.
Ključne besede: aluminium, chlorides, self-assembled monolayer, localized corrosion, density-functional theory
Objavljeno v DiRROS: 29.04.2025; Ogledov: 27; Prenosov: 8
Celotno besedilo (2,33 MB)
Gradivo ima več datotek! Več... |
6. |
7. A general-purpose adsorption isotherm for improved estimation of standard adsorption free energyAnton Kokalj, 2023, izvirni znanstveni članek Povzetek: A new general-purpose Type–I adsorption isotherm is proposed to improve standard adsorption Gibbs energy estimation. This new isotherm stems from considering a functional dependence of various adsorption models on the �∕� vs. � plot, where � is the fractional surface coverage and � the concentration. It can accurately describe many adsorption isotherms, implying that it is flexible enough to describe various adsorption scenarios. Among the tested adsorption models that the new isotherm can describe are those that consider lateral inter-adsorbate interactions, molecular size, surface heterogeneity, and mobile adsorption.
Ključne besede: standard adsorption free energy, corrosion inhibitors, adsorption isotherms
Objavljeno v DiRROS: 29.04.2025; Ogledov: 22; Prenosov: 7
Celotno besedilo (2,52 MB)
Gradivo ima več datotek! Več... |
8. Corrosion of synthetic intermetallic compounds and AA7075-T6 in dilute Harrison's solution and inhibition by cerium(III) saltsPeter Rodič, Ingrid Milošev, Gerald S. Frankel, 2023, izvirni znanstveni članek Povzetek: This study addresses the behavior of an aluminum alloy and its components in conditions simulating the presence of atmospheric salts. The corrosion of synthetic intermetallic compounds (IMCs) Al2Cu, Al2CuMg, Al7Cu2Fe, MgZn2, and bulk aluminum alloy 7075-T6 was studied in dilute Harrison’s solution (DHS, 0.35 wt% (NH4)2SO4 + 0.05 wt% NaCl). For IMCs, electrochemical measurements were performed using a microcell, and a standard electrochemical cell was used to study the bulk alloy. Separately measured cathodic and anodic potentiodynamic polarization curves were recorded, and prolonged immersion was characterized using electrochemical impedance spectroscopy. Samples were characterized using scanning electron microscopy, energy-dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy. Bulk AA7075-T6 was less susceptible to corrosion in DHS than in chloride solution stemming from the beneficial presence of sulfate ions and lower chloride concentration. The susceptibility of IMCs to corrosion in DHS increased in the order Al2Cu < Al7Cu2Fe < Al2CuMg < MgZn2 due to the increased dissolution of Mg in the presence of ammonium ions. The relative nobility of IMCs was determined based on the galvanic current density. Further, the possibility of using cerium chloride, nitrate and acetate salts as corrosion inhibitors in DHS was evaluated. Ce salts acted as inhibitors for the alloy during 14 d testing, forming a Ce hydroxide layer. The degree of protection depended on the type of anion, with acetate Ce salt giving the most efficient protection. For the IMC, however, inhibition by Ce salts did not occur during short measurements in the microcell, indicating the importance of galvanic interaction with the alloy matrix in the inhibition mechanism, which was confirmed by long-term measurements of the alloy.
Ključne besede: aluminum alloy, atmospheric salts, corrosion, sample characterization
Objavljeno v DiRROS: 29.04.2025; Ogledov: 27; Prenosov: 12
Celotno besedilo (4,15 MB)
Gradivo ima več datotek! Več... |
9. 2-rainbow independent domination in complementary prismsDragana Božović, Gordana Radić, Aleksandra Tepeh, 2025, izvirni znanstveni članek Povzetek: A function f that assigns values from the set {0,1,2} to each vertex of a graph is called a 2-rainbow independent dominating function, if the vertices assigned the value 1 form an independent set, the vertices assigned the value 2 form another independent set, and every vertex to which 0 is assigned has at least one neighbor in each of the mentioned independent sets. The weight of this function is the total number of vertices assigned nonzero values. The 2-rainbow independent domination number of G, γri2(G), is the minimum weight of such a function. Motivated by a real-life application, we study the 2-rainbow independent domination number of the complementary prism G¯G of a graph G, which is constructed by taking G and its complement ¯G, and then adding edges between corresponding vertices. We provide tight bounds for γri2(G¯G), and characterize graphs for which the lower bound, i.e. max, is attained. The obtained results can, in practice, enable the prediction of the cost estimate for a given communication or surveillance network.
Ključne besede: graph theory, domination, 2-rainbow independent domination, complementary prism
Objavljeno v DiRROS: 28.04.2025; Ogledov: 40; Prenosov: 7
Celotno besedilo (366,61 KB)
Gradivo ima več datotek! Več... |
10. |
