Search results for "DEGRADATION"
showing 10 items of 1208 documents
SnO2 : Sb - A new material for high-temperature MEMS heater applications: Performance and limitations
2007
MEMS micro heater devices capable of long-term operation at temperatures up to 1000 degrees C are presented. The enhanced long-term stability has been achieved by employing antimony-doped tin oxide (SnO2:Sb) as a substitute for the conventionally used noble metal heater resistors. A detailed investigation of its high-temperature stability reveals that degradation is caused by out-diffusion of Sb impurities from the SnO2 film. (c) 2007 Elsevier B.V. All rights reserved.
Paper Functionalized with Nanostructured TiO2/AgBr: Photocatalytic Degradation of 2–Propanol under Solar Light Irradiation and Antibacterial Activity
2020
A facile method to produce paper&ndash
A grain-scale model for high-cycle fatigue degradation in polycrystalline materials
2018
Abstract A grain-scale three-dimensional model for the analysis of fatigue intergranular degradation in polycrystalline materials is presented. The material microstructure is explicitly represented through Voronoi tessellations, of either convex or non-convex domains, and the mechanics of individual grains is modelled using a boundary integral formulation. The intergranular interfaces degrade under the action of cyclic loads and their behaviour is represented employing a cohesive zone model embodying a local irreversible damage parameter that evolves according to high-cycle continuum damage laws. The model is based on the use of a damage decomposition into static and cyclic contributions, a…
Comparison of resistance to damage of unalloyed carbon steels under the influence of hydrogen
2018
One of the most commonly used construction material in industry is unalloyed steel S235 and S355. These types of steel are used for construction of ships, bridges, coastal construction, welded tanks, and in buildings. Due to the operating conditions, these types of steel may undergo hydrogen degradation in the process of manufacturing of welded structures or when operating the structures. This paper presents the results of study into resistance of selected types of non-alloy structural steels to hydrogen degradation. Tests were carried out to determine changes in mechanical properties in the static trials of stretching without hydrogen, and after saturation with hydrogen. Parallel fractogra…
Lignocellulosic fillers and graphene nanoplatelets as hybrid reinforcement for polylactic acid: Effect on mechanical properties and degradability
2020
Abstract This work investigates the effect of adding relatively low amounts of graphene nanoplatelets (GNP) to a biocomposite based on polylactic acid (PLA) and a lignocellulosic filler achieved by grinding Posidonia Oceanica leaves (Posidonia flour, PF). The ternary composites were prepared by melt extrusion and characterized from a morphological and mechanical point of view. Furthermore, hydrolytic degradation tests were performed under acidic, neutral and alkaline environment up to 900 h. Density measurements enabled to assess the degree of intraphase, i.e. the capability of polymer macromolecules to enter the voids of PF and a modified Halpin-Tsai model was presented and used to fit exp…
Frequency-Downconversion Stability of PMMA Coatings in Hybrid White Light-Emitting Diodes
2015
We report on the properties of a poly(methyl methacrylate)-based coating used as a host for an organic dye in hybrid white light-emitting diodes. The device is composed by a pump source, which is a standard inorganic GaN/InGaN blue light-emitting diode (LED) emitting at around 450 nm, and a spin-coated conversion layer making use of Lumogen® F Yellow 083. Under prolonged irradiation, the coating exhibits significant bleaching, thus degrading the color rendering performance of the LED. We present experimental results that confirm that the local temperature rise of the operating diode does not affect the conversion layer. It is also proven that, during the test, the photostability of the orga…
Degradation of fluoride-free MIL-100(Fe) and MIL-53(Fe) in water: Effect of temperature and pH
2016
Abstract The degradation in liquid water of two iron-containing MOFs MIL-100(Fe) and MIL-53(Fe) synthesized in fluoride-free conditions was studied. It was found that dispersing the MOFs in deionized water (1 mg/mL) results in the decrease of pH to 2.9 for MIL-100(Fe) and to 4.5 for MIL-53(Fe). Given this finding the stability of the MOFs in liquid water was characterized under two different sets of conditions: 1) reflux in water at 100 °C under obtained pH and 2) at ambient temperature under adjusted pH 7. After reflux of MIL-100(Fe) at 100 °C its XRD pattern remains unchanged, however a strong decrease of its BET surface area and appearance of α-Fe 2 O 3 nanoparticles point out to a parti…
Facile synthesis of magnetically separable CoFe2O4/Ag2O/Ag2CO3 nanoheterostructures with high photocatalytic performance under visible light and enha…
2017
Riga Technical University supported the preparation of this manuscript from the Scientific Research Project Competition for Young Researchers No. ZP-2016/7. The authors wish to kindly acknowledge the financial support of HZB, Estonian Research Council (PUT1096, PUT735 and IUT2-25) and Estonian Centre of Excellence in Research Project “Advanced materials and high-technology devices for sustain-able energetics, sensorics and nanoelectronics” TK141 (2014–2020.4.01.15-0011).
A comparative study of fatigue behaviour of flax/epoxy and glass/epoxy composites
2012
Experimental investigations on flax and glass fabrics reinforced epoxy specimens, i.e. FFRE and GFRE, submitted to fatigue tests are presented in this paper. Samples having [0/90]3S and [±45]3S stacking sequences, with similar fibre volume fractions have been tested under tension–tension fatigue loading. The specific stress-number of cycles to failure (S–N) curves, show that for the [0/90]3S specimens, FFRE have lower fatigue endurance than GFRE, but the [±45]3S FFRE specimens offer better specific fatigue endurance than similar GFRE, in the studied life range (<2 × 10^6). Overall, the three-stage stiffness degradation is observed in all cases except for [0/90]3S FFRE specimens, which prese…
High temperature alloy chloridation at 850°C
2007
The resistance of eight alloys against chloridation was tested at 850 °C in Ar/Cl 2 (2.5% Cl 2 ) for 15 min. Pre-oxidation treatments were performed for 1 h and 8 h at 850°C in order to produce a thin, adherent and protective oxide scale able to improve the chloridation behaviour of the tested materials. The chloridised sample morphologies were compared to the morphologies observed on the non pre-oxidised samples. The alloys containing a large amount of iron did not exhibit any chloridation resistance, even after pre-oxidation, and were severely damaged. The nickel based alloys gave interesting results but were also attacked by chloride, probably by the "active oxidation" mechanism. The dur…