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Povzetek: The effect of chemical pretreatment of aluminium alloy 7075-T6 on the composition, morphology, and structure of zirconium conversion coatings (ZrCC) was investigated. Chemical pretreatments included: (i) alkaline etching and desmutting using commercial reagents, (ii) alkaline etching using sodium hydroxide, (iii) acidic etching using nitric acid, (iv) desmutting using a commercial reagent and boiling in deionised water, and (v) alkaline etching and desmutting using nitric acid. ZrCCs were deposited at room temperature from a 200 ppm H2ZrF6 solution of pH 4.8. A commercial SurTec® coating containing zirconium and trivalent chromium was used as a benchmark. The electrochemical behaviour was evaluated using potentiodynamic polarisation measurements and electrochemical impedance spectroscopy conducted over a minimum of 5 days and up to 15 days in 0.1 M NaCl. Corrosion resistance was further assessed through immersion testing. Microstructural characterisation was performed using scanning electron microscopy with energy-dispersive spectroscopy, X-ray photoelectron spectroscopy, and time-of-flight secondary ion mass spectrometry. The SurTec® pretreatment of AA7075-T6 activated the self-sealing of the subsequently deposited ZrCC, about 40 nm thick, which exhibited the highest degree of compactness and uniformity. This study showed a significant impact of surface chemical pretreatment on the microstructural and protective properties of ZrCCs deposited on 7075 alloy.
Ključne besede: surface pretreatment, etching, desmutting
Objavljeno v DiRROS: 18.11.2025; Ogledov: 184; Prenosov: 81
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Povzetek: In comparison to non-combustible construction materials commonly used for taller buildings, timber elements can significantly alter the fire dynamics in a compartment. This fundamentally challenges many of the conventional fire safety strategies and design approaches for mid-rise and high-rise buildings. Consequently, many building industry practitioners are questioning the limitations of existing methodologies, while searching for additional ways to account for this different fire behaviour in the design, construction, and operation of timber buildings. In seeking to address these questions, this chapter describes the state-of-the-art and recent advances in understanding the fire behaviour in compartments with areas of exposed timber (e.g., engineered wood products), and protected timber elements that may contribute to the fire if their encapsulation fails. Relevant experimental findings and engineering approaches to date are summarised and discussed, and design guidance is provided in relation to the typical phases of realistic or ‘natural’ fires, namely the growth phase, the fully-developed phase, the fire decay, and the cooling phase. Critical fire phenomena and their impacts on the fire safety strategy are addressed, such as fire spread; active fire suppression; heat induced delamination and char fall-off; and self-extinguishment.
Ključne besede: timber, fire dynamics, fire safety, self-extinguishment, heat induced delamination, char fall-off
Objavljeno v DiRROS: 18.11.2025; Ogledov: 162; Prenosov: 73
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Ključne besede: food marketing, children, food packaging, nutritional composition, nutrient profiling
Objavljeno v DiRROS: 18.11.2025; Ogledov: 153; Prenosov: 62
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Povzetek: Fire safety and fire protection objectives require that buildings and parts of buildings do not collapse during a fire. This requires that the load-carrying capacity is maintained to a minimum acceptable level during a fire. This chapter briefly describes the historical background and state of the art of fire resistance and its determination for timber members through testing or calculations. The thermal and mechanical principles that underpin structural behaviour of wood at elevated temperatures are explained in the context of explicit calculation methods that enable explicit evaluation of the structural capacity beyond fire resistance, which is a formalised and codified assessment of structural elements against a standard fire. The importance of connections to the overall structure in fire is explained along with suitable design considerations. Ultimately, knowledge gaps with respect to novel and more complex engineered timber products for taller timber buildings are highlighted alongside potential limitations of established design parameters.
Ključne besede: fire resistance, fire safety, structures, load-carrying capacity, timber, connections
Objavljeno v DiRROS: 18.11.2025; Ogledov: 161; Prenosov: 69
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Ključne besede: free sugar, sugar intake, dietary intake, 24-hour recall, nutrition survey, public health, EU Menu, Slovenia
Objavljeno v DiRROS: 18.11.2025; Ogledov: 156; Prenosov: 70
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