1. Diketopyrrolopyrrole pigment core@multi-layer ▫$SiO_2$▫ shell with improved photochemical stabilityErika Švara Fabjan, Zineb Saghi, Paul A. Midgley, Mojca Otoničar, Goran Dražić, Miran Gaberšček, Andrijana Sever Škapin, 2018, izvirni znanstveni članek Povzetek: A model organic pigment (diketopyrrolopyrrole) is encapsulated by a silica coating in order to improve its photochemical stability. Unlike in previous works where single-layer silica coatings were used for similar purposes, we here propose creation of a multi-layer silica shell synthesized via in-situ sol-gel method, which should significantly improve the homogeneity and thus the protection ability of the coating. This is done by repeating the basic two-step process (pigment surface modification and silica encapsulation) several times, creating the final protective shell in a layer-by-layer fashion. The compositional and structural properties of the prepared coatings is studied using Fourier-transform infrared spectroscopy, differential thermal and thermogravimetric analysis, nitrogen adsorption measurements and transmission electron microscopy. Photochemical stability of non-encapsulated and encapsulated pigment particles is evaluated via the so-called fast-irradiation method. Various correlations between the essential coating properties, such as thickness, porosity, SiO2 content, and the corresponding photochemical stability of the samples are established and discussed in detail. As a whole, our results confirm the basic hypothesis, that multiple-layered silica shells show improved pigment protection ability in comparison to the single-layer coatings.
Ključne besede: organic pigments, silica coating, encapsulation, morphology, photocemical stability
Objavljeno v DiRROS: 27.03.2024; Ogledov: 120; Prenosov: 54
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2. In vitro evaluation of stress corrosion cracking susceptibility of PEO-coated rare-earth magnesium alloy WE43Julia Nachtsheim, Songyun Ma, Jaka Burja, Bernd Markert, 2024, izvirni znanstveni članek Ključne besede: stress corrosion cracking, PEO coating, biodegradable magnesium alloys, SCC test setup, in vitro experiments
Objavljeno v DiRROS: 07.02.2024; Ogledov: 163; Prenosov: 78
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3. High temperature friction and galling properties of nanolayered (Cr,V)N coatings and effect of V contentBojan Podgornik, Marko Sedlaček, Barbara Šetina, Miha Čekada, 2023, izvirni znanstveni članek Ključne besede: (Cr, V)N coating, galling, high-temperature tribology, hot forming, self-lubrication
Objavljeno v DiRROS: 26.01.2024; Ogledov: 205; Prenosov: 128
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4. Efficiency of novel photocatalytic coating and consolidants for protection of valuable mineral substratesAndreja Pondelak, Sabina Dolenec, Jonjaua Ranogajec, Luka Škrlep, Snezana B. Vučetić, Vilma Ducman, Andrijana Sever Škapin, 2019, izvirni znanstveni članek Povzetek: In the process of protection and consolidation of valuable materials, the efficiency is the crucial property that needs to be considered. TiO2/ZnAl layered double hydroxide (LDH) coating and silicate- and carbonate-based consolidants were synthesized and proposed to be used for protection and consolidation of four porous mineral substrates: brick, stone, render and mortar. The photocatalytic efficiency of TiO2/ZnAl LDH coating, as well as consolidation efficiency of two consolidants, both applied on model substrates, were studied. The photocatalytic coating showed significant activity and performed well after the durability tests involving rinsing and freezing/thawing procedures. After treatment with both consolidants, a serious enhancement of consolidation of the used substrates was found. On the other hand, the application of TiO2/ZnAl LDH, as well as consolidants, caused negligible changes in the water vapour permeability values and in appearance of the porous mineral substrates, indicating a high level of compatibility.
Ključne besede: photocatalytic coating, consolidant, protection, conservation, porous substrate, cultural heritage
Objavljeno v DiRROS: 21.11.2023; Ogledov: 233; Prenosov: 173
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5. Development of multi-component fluoropolymer based coating on simulated outdoor patina on quaternary bronzeTadeja Kosec, Luka Škrlep, Erika Švara Fabjan, Andrijana Sever Škapin, Giulia Masi, Elena Bernardi, Cristina Chiavari, Claudie Josse, Jerome Esvan, Luc Robbiola, 2019, izvirni znanstveni članek Povzetek: Bronze reacts with oxygen, humidity, and pollutants in the atmosphere so that a patina forms. Natural exposure to an outdoor atmosphere can be simulated and accelerated in order to achieve a patina that mimics outdoor ancient patina. In order to avoid the uncontrolled dissolving of either the natural or artificially formed patina, protection of the patina is needed.
In this study, a multi-component fluoropolymer based coating for the protection of bronze patina was developed. In order to provide various functionalities of the coating (such as the hydrophobicity of the coating surface, obtaining interactions within the coating itself as well as a bronze substrate and inhibiting the corrosion processes), a fluoroacrylate coating with appropriate adhesion promoter was suggested, with and without a silane modified benzotriazole inhibitor. The protective efficiency and durability of the applied coatings were investigated electrochemically using potentiodynamic tests and electrochemical impedance spectroscopy in a simulated acid rain solution. All of the developed coatings showed a significant decrease in the corrosion current density. The self-assembled single layer coating (FA-MS) also showed 100% inhibition efficiency. After ageing the coating remained transparent and did not change by UV exposure and/or thermal cycling. The patina and coating investigations using FIB-SEM and EDX showed that the latter coating (FA-MS) successfully covered the surface of the patinated bronze. The mechanism of the bonding was proposed and supported with the spectroscopic observation of a thin and even coating.
Ključne besede: bronze, patina, fluoropolymer coating, atmospheric corrosion
Objavljeno v DiRROS: 25.10.2023; Ogledov: 345; Prenosov: 186
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6. Exploring the protection mechanism of a combined fluoropolymer coating on sulphide patinated bronzeTadeja Kosec, Živa Novak, Erika Švara Fabjan, Luka Škrlep, Matjaž Finšgar, 2022, izvirni znanstveni članek Povzetek: When bronze or artificially patinated bronze is exposed to an outdoor environment that contains aggressive ions such as sulphates, nitrates, and carbonates, the surface of the bronze changes its appearance due to the formation of corrosion products on the surface. Research is being conducted on versatile protective measures that can be used to protect the surface from these changes. A recently synthesised fluoropolymer-based coating with mercaptopropyl groups, i.e. a 3-component fluoropolymer coating FA-MS-SH (silane-modified poly methylmethacrylate (MS) with added mercaptopropyltrimethoxy silane (SH) and a fluoroacrylate (FA)) was explored in detail in this work where its protective mechanism on sulphide patinated bronze was investigated. Electrochemical tests were conducted on the sulphide patinated bronze with and without the 3-component coating FA-MS-SH. Furthermore, FA, MS and SH alone and various combinations and concentrations of FA-MS were studied in order to determine the protective effect and properties of each component. Colour change and contact angle measurements were also defined. FIB-SEM measurements and GCIB-XPS depth profiles were carried out to study surface bonding with the sulphide patina in detail.
A mechanism for the protection of sulphide patinated bronze was presented through the use of a multianalytical tool approach. It was shown that FA physisorbed on the patinated surface, while MS and blends of the components chemisorbed on the layer of sulphide patinated bronze, also resulting in the surface being efficiently protected from corrosion processes.
Ključne besede: bronze, protection, brown patina, fluoropolymer coating
Objavljeno v DiRROS: 31.05.2023; Ogledov: 330; Prenosov: 193
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7. Properties of the fluoroacrylate and methacryloxypropyl-trimethoxysilane applied to a layer of Cu2O on bronze as either single or multi-component coatingsLuka Škrlep, Tadeja Kosec, Matjaž Finšgar, Andrijana Sever Škapin, Erika Švara Fabjan, 2023, izvirni znanstveni članek Povzetek: Various coatings have been developed and explored to protect bronze surfaces against the uncontrolled formation of different corrosion products when exposed to outdoor environments.
In this research, the surfaces of artificially-formed oxidized bronze patinas (OB), consisting of Cu2O, were covered with either a single-component (fluoroacrylate, FA or methacryloxypropyl-trimethoxysilane, MS) or multi-component (a mixture of FA and MS, FA-MS) fluoropolymer coating and investigated. Variations in the concentration of each component in the coating were studied. Electrochemical tests were performed to determine the corrosion protection efficiency, followed by detailed surface analyses of the OBs, both uncoated and covered with single and multi-component coatings. A variety of investigative methods were used, including focused ion beam scanning electron microscopy (FIB-SEM), X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and time-of-flight secondary ion mass spectrometry (ToF-SIMS).
The coating made from a combination of FA and MS resulted in a very high protection efficiency. Despite the increased hydrophilicity of the single MS component, however, it was shown to efficiently protect the oxidized bronze surface. The FA-MS systems showed high hydrophobicity, but no improvement was measured in the efficiency of the corrosion protection when it was compared to the coating that contained 10% MS. According to XPS and ToF-SIMS imaging, the FA component of the FA-MS coating was not present only on the uppermost surface of the coating but throughout the whole coating, which could affect its corrosion protection efficiency.
Ključne besede: bronze, Cu2O layer on bronze, fluoropolymer coating, protection efficiency, surface spectroscopy
Objavljeno v DiRROS: 30.05.2023; Ogledov: 333; Prenosov: 178
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8. Sustainable biocarbon/tung oil coatings with hydrophobic and UV-shielding properties for outdoor wood substratesLaetitia Sarah Jennifer Marrot, Mariem Zouari, Matthew Schwarzkopf, David Brian DeVallance, 2023, izvirni znanstveni članek Povzetek: With wood regaining substantial interest as a construction material due to sustainability concerns and aesthetics trends, efficient and safe protection methods are needed to prevent the discouloration and the loss of mechanical properties of this renewable and UV-sensitive material. In this study, sustainable coatings comprising 0 to 20 wt % biocarbon (BC) dispersed in tung oil were developed for wood protection. BC particles were added as ultraviolet (UV) absorbers and were produced by various carbonization routes. The BC powders were characterized in terms of particle size and surface functional groups by Fourier-Transform infrared, and the UV and visible absorbance of dispersed BC powders in water solutions were related to these characteristics.
Two wooden substrates (beech and oak) were coated with the developed coatings and the samples underwent six months of onsite weathering. While the total colour change of uncoated samples and tung oil-coated substrates without BC kept increasing over time and resulted in a clear alteration of the wood surface aesthetics, an increased BC content in the coatings led to enhanced colour stability, with alteration of the colour close to 2 for both wood species after six months of weathering for 10 and 20 wt% BC.
Coating with tung oil made the wooden substrates, initially hydrophilic, become hydrophobic, and the further introduction of biocarbon increased hydrophobicity. However, the increase in BC content was not correlated with an increase in water repellence, the highest water contact angle being observed for 5 % BC, and no further improvement in hydrophobicity was observed with higher BC content. The weathering negatively affected the water repellence of all the samples (i.e., reference samples and coated samples with various BC content). However, the introduction of 20 % BC best protected the decrease in water repellence induced by the onsite weathering.
Ključne besede: biocarbon, biochar, coating, wood protection, hydrophobic coating, wettability
Objavljeno v DiRROS: 30.05.2023; Ogledov: 317; Prenosov: 398
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9. Effect of CeO[sub]2 doping on the microstructure and corrosion behavior of CoCuNiTi high-entropy alloy coatingsMing-xing Ma, Liang Zhao, Zhi-xin Wang, Shang-zhi Li, Chen Dong, 2021, izvirni znanstveni članek Ključne besede: high-entropy alloy coating, CoCuNiTi, microstructure, corrosion behavior, laser cladding
Objavljeno v DiRROS: 06.05.2022; Ogledov: 515; Prenosov: 121
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10. Effect of silsesquioxane addition on the protective performance of fluoropolymer coatings for bronze surfacesMohor Mihelčič, Miran Gaberšček, Martina Salzano de Luna, Marino Lavorgna, Chiara Giuliani, Gabriella Di Carlo, Angelja Kjara Surca, 2019, izvirni znanstveni članek Ključne besede: bronze, protective coating, nanocomposite, fluoropolymer, POSS nanoparticle, nanoindentation
Objavljeno v DiRROS: 04.12.2019; Ogledov: 2116; Prenosov: 1411
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