scholarly journals Silicon Oxycarbide and Silicon Oxycarbonitride Materials under Concentrated Solar Radiation

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 1013
Author(s):  
M. Alejandra Mazo ◽  
Isabel Padilla ◽  
Aurora López-Delgado ◽  
Aitana Tamayo ◽  
Juan Rubio
Keyword(s):  
Solar Radiation ◽  
Thermal Shock ◽  
Fresnel Lens ◽  
Silicon Oxycarbide ◽  
Accelerated Ageing ◽  
Silica Layer ◽  
Fast Heating ◽  
Solar Absorbers ◽  
Before And After ◽  
Silicon Oxycarbonitride

The potential application of silicon oxycarbonitride (SiOCN), silicon oxycarbide (SiOC) and silicon oxycarbide–SiC (SiOC–SiC) for photothermal devices such as volumetric solar absorbers has been studied evaluating the response to thermal shock from a Fresnel lens. The accelerated ageing test comprises fast heating (32 °C min−1) and cooling rates (27 °C min−1) from 100 to 1000 °C and dwelling times of 10 min. Porous materials (SiOCNp and SiOCp) failed the thermal shock tests; they were massively degraded by the formation of a large depression in the focus of solar radiation. Dense materials (SiOCd and SiOC–SiCd) withstood 100 cycles of thermal shock ageing tests due to the formation of a protective silica layer. The absorptance values for dense materials remained fairly constant before and after thermal shock tests: from 94.5 to 94.3% for SiOCd and from 93.3 to 93.3% for SiOC–SiCd. These preliminary studies indicate their potential for high-temperature solar receiver applications.

Influence of the Zinc Sublayer Method Production and Heat Treatment on the Microhardness of the Composite Ni-Al2O3 Coating Deposited on the 5754 Aluminium Alloy

2014 ◽  
Vol 59 (1) ◽  
pp. 355-358
Author(s):  
M. Karaś ◽  
M. Nowak ◽  
M. Opyrchał ◽  
M. Bigaj ◽  
A. Najder
Keyword(s):  
Heat Treatment ◽  
Aluminium Alloy ◽  
Thermal Shock ◽  
Nickel Coating ◽  
Nickel Sulphate ◽  
Al2o3 Coating ◽  
Nickel Coatings ◽  
Watts Bath ◽  
Before And After ◽  
Zinc Interlayer

Abstract In this study, the effect of zinc interlayer on the adhesion of nickel coatings reinforced with micrometric Al2O3 particles was examined. Nickel coating was applied by electroplating on EN AW - 5754 aluminium alloy using Watts bath at a concentration of 150 g/l of nickel sulphate with the addition of 50 g/l of Al2O3. The influence of zinc intermediate coating deposited in single, double and triple layers on the adhesion of nickel coating to aluminium substrate was also studied. The adhesion was measured by the thermal shock technique in accordance with PN-EN ISO 2819. The microhardness of nickel coating before and after heat treatment was additionally tested. It was observed that the number of zinc interlayers applied does not significantly affect the adhesion of nickel which is determined by thermal shock. No defect that occurs after the test, such as delamination, blistering or peeling of the coating was registered. Microhardness of the nickel coatings depends on the heat treatment and the amount of zinc in the interlayer. For both single and double zinc interlayer, the microhardness of the nickel coating containing Al2O3 particles increased after heat treatment, but decreased when a triple zinc interlayer was applied.

Effect of preset interfacial ZrB2 particles on the microstructure and properties of C/C-AlSi composites

2021 ◽  
pp. 002199832110046
Author(s):  
Wei Feng ◽  
Chengwei Tang ◽  
Lei Liu ◽  
Jian Chen ◽  
Yang Zhang ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Thermal Expansion ◽  
Thermal Shock ◽  
Retention Rate ◽  
Pressure Infiltration ◽  
Micro Scale ◽  
Before And After ◽  
Micro Morphology ◽  
Strength Retention ◽  
Fiber Fabric

ZrB2 particles were preset to the C-AlSi interface to improve oxidation resistance of C/C preform and adjust the microstructure of the interpenetrated C/C-AlSi composite prepared through pressure infiltration of eutectic AlSi into a fiber fabric based porous C/C skeleton. Micro-morphology investigations suggested that the AlSi textures were changed from dendritic to petals-like state, and the nano to micro-scale ZrB2 particles were dispersed into AlSi and affected the distribution of Al and Si nearby carbon. Tests demonstrated that C/C-AlSi have slight lower density and thermal expansion coefficient, and higher original compressive strength, while C/C-ZrB2-AlSi composites presented an outstanding strength retention rate after thermal shock. Fracture and micro-morphology indicated that the influence of the preset ZrB2 to the interface of carbon and alloy greatly affected the generation and propagation of cracks, which determined the diverse compression behaviors of the composites before and after thermal shock.

scholarly journals Nanomaterials for Combined Stabilisation and Deacidification of Cellulosic Materials—The Case of Iron-Tannate Dyed Cotton

Nanomaterials ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 900 ◽  
Author(s):  
Nicoletta Palladino ◽  
Marei Hacke ◽  
Giovanna Poggi ◽  
Oleksandr Nechyporchuk ◽  
Krzysztof Kolman ◽  
...  
Keyword(s):  
Silica Nanoparticles ◽  
High Efficiency ◽  
Complex Structure ◽  
Fibre Surface ◽  
Inorganic Nanoparticles ◽  
Accelerated Ageing ◽  
Length Scales ◽  
Before And After ◽  
Colour Changes ◽  
Apparent Colour

The conservation of textiles is a challenge due to the often fast degradation that results from the acidity combined with a complex structure that requires remediation actions to be conducted at several length scales. Nanomaterials have lately been used for various purposes in the conservation of cultural heritage. The advantage with these materials is their high efficiency combined with a great control. Here, we provide an overview of the latest developments in terms of nanomaterials-based alternatives, namely inorganic nanoparticles and nanocellulose, to conventional methods for the strengthening and deacidification of cellulose-based materials. Then, using the case of iron-tannate dyed cotton, we show that conservation can only be addressed if the mechanical strengthening is preceded by a deacidification step. We used CaCO3 nanoparticles to neutralize the acidity, while the stabilisation was addressed by a combination of nanocellulose, and silica nanoparticles, to truly tackle the complexity of the hierarchical nature of cotton textiles. Silica nanoparticles enabled strengthening at the fibre scale by covering the fibre surface, while the nanocellulose acted at bigger length scales. The evaluation of the applied treatments, before and after an accelerated ageing, was assessed by tensile testing, the fibre structure by SEM and the apparent colour changes by colourimetric measurements.

Properties of Ceramic Coatings on the Wall of Coke Oven

2011 ◽  
Vol 189-193 ◽  
pp. 1105-1108
Author(s):  
Shu Xian Liu ◽  
Li Li Shen ◽  
Qian Ping Wang
Keyword(s):  
Thermal Shock ◽  
Thermal Shock Resistance ◽  
High Hardness ◽  
Coke Oven ◽  
Ceramic Coatings ◽  
Good Adhesion ◽  
Before And After ◽  
Shock Resistance ◽  
Uncoated Specimen ◽  
Better Than

Flame sprayed ceramic coatings on the wall of coke oven are characterized before and after melting. The attempt has been made to investigate thermal shock resistant, carbon deposit resistant, wear resistant of the coated and melted samples. The techniques used are SEM and XRD. The results show that: 1) Presence of quartz, corundum and mullite are identified in the surface of the coated specimen. Good adhesion between the coating and the substrate is caused by presence of quartz which is the same content as the substrate.2) The thermal shock resistance cycles of the coating samples are 15 ~ 30 times, but uncoated samples are only 1~2 times. The main reason is that he coating–substrate interface shows no gaps or cracks, and it has a characteristic feature of good adhesion between the coating and the substrate. 3) The wear resistance of the coated samples are better than that of the uncoated samples because glass-coating is more smooth than the uncoated specimen and the mullite and corundum in the coating have the high hardness value that makes the hardness of the coating increased.

Does Eumelanin Oxidation Play a Role on the Photostability of Ethyl Glucuronide in Hair Exposed to Simulated Solar Radiation?

2020 ◽  
Author(s):  
Giorgia Miolo ◽  
Benedetta Vicario ◽  
Giulia Stocchero ◽  
Valerio Causin ◽  
Susanna Vogliardi ◽  
...  
Keyword(s):  
Solar Radiation ◽  
Sun Exposure ◽  
Tricarboxylic Acid ◽  
Sem Analysis ◽  
Ethyl Glucuronide ◽  
Brown Hair ◽  
Hair Samples ◽  
Before And After ◽  
Simulated Solar Radiation ◽  
Scanning Electron

Abstract The action of solar radiation on the concentration of the ethanol metabolite ethyl glucuronide (EtG) in 40 hair samples of nonabstinent subjects was investigated. Hair samples of different colors were analyzed before and after irradiation with artificial sunlight under a light dose corresponding to 3 months of sun exposure. After irradiation, an increase of EtG concentration was detected in 55% of the samples ranging from 5% to 141%. In 16 cases, a concentration reduction ranging from −2% to −74% was observed. The measure of the level of pyrrole-2,3,5-tricarboxylic acid (PTCA), a marker of eumelanin oxidation, demonstrated the largest increase in oxidation in light brown hair where the greatest degradation of EtG was observed after irradiation. However, the rise of PTCA in all hair tested was accompanied by increase in EtG concentration in 8/10 samples and by decrease in 2/10, suggesting no correlation between the two markers. To verify if hair structure was modified by light, scanning electron microscopy (SEM) analysis was performed on irradiated hair of different colors and compared with the dark samples. SEM revealed modification of hair structure in all samples showing partial shaft exfoliation and reduction of hair thickness under the treatment with solar radiation.

Evaluation of thermal shock resistance of silicon oxycarbide materials for high-temperature receiver applications

Solar Energy ◽  
2018 ◽  
Vol 173 ◽  
pp. 256-267 ◽  
Author(s):  
M. Alejandra Mazo ◽  
Isabel Padilla ◽  
Aitana Tamayo ◽  
José I. Robla ◽  
Aurora López-Delgado ◽  
...  
Keyword(s):  
High Temperature ◽  
Thermal Shock ◽  
Thermal Shock Resistance ◽  
Silicon Oxycarbide ◽  
Shock Resistance

Spectrophotometric Measurements of Noctilucent Clouds

1973 ◽  
Vol 51 (4) ◽  
pp. 373-377 ◽  
Author(s):  
A. W. Harrison
Keyword(s):  
Solar Radiation ◽  
Infrared Spectra ◽  
Near Infrared ◽  
Noctilucent Clouds ◽  
Near Infrared Spectra ◽  
Before And After

Near infrared spectra of a NLC display are compared with spectra from the normal twilight sky for the regions 7850 to 9000 Å and 2.8 to 4.2 μ showing that NLC's are scatterers of solar radiation. Airglow hydroxyl rotational temperatures and intensities were monitored for several nights before and after the display but show no obvious correlation in behavior with this single NLC occurrence.

Mechanical Properties of Winding Conductors Affected by Cyclic Thermal Overloads

2006 ◽  
Vol 113 ◽  
pp. 541-544 ◽  
Author(s):  
N. Višniakov ◽  
J. Novickij ◽  
D. Ščekaturovienė ◽  
M. Šukšta
Keyword(s):  
Mechanical Properties ◽  
Metal Matrix ◽  
Room Temperature ◽  
Pure Copper ◽  
Testing Machine ◽  
Liquid Nitrogen Temperature ◽  
Ultimate Tensile Stress ◽  
Climatic Chamber ◽  
Fast Heating ◽  
Before And After

The influence of thermal cyclic overloads on mechanical properties of winding conductors was investigated. Copper-niobium microcomposite, soft and hard pure copper wires were conditioned at temperatures range from 77 K to 500 K. The treatment was done during 100 cycles of fast conductor cooling to liquid nitrogen temperature and further fast heating in a climatic chamber. The ultimate tensile stress limit and the elongation at failure of metal-matrix copper-niobium microcomposite, soft and hard copper wires were measured before and after thermal treatment with a testing machine at room temperature.

Optical Parameters in High-Efficiency Optical Receivers With a Parabolic Reflector Before and After Coating With Ag Film

2013 ◽  
Vol 136 (2) ◽  
Author(s):  
Chung Jui Lee ◽  
Jen Fin Lin
Keyword(s):  
High Efficiency ◽  
Film Coating ◽  
Fresnel Lens ◽  
Optical Parameters ◽  
Optical Receivers ◽  
Profile Error ◽  
Optical Efficiency ◽  
Aspheric Lens ◽  
Before And After ◽  
Ag Film

High-efficiency optical receivers before and after the coating of Ag film are composed of a parabolic reflector, a solid parabolic second optical element (SOE), and a Fresnel/aspheric concentrating lens. The optical receivers before the Ag-film coating are fabricated on a high-precision machine tool based on an optimum design attained from ray tracing software simulations. The real profiles of the reflector before and after coating the Ag film are found to be the average of the two orthogonal parabolic profiles. They are then compared to the perfect profile (without profile error and surface roughness) in order to investigate the influence of the profile error and the Ag film on optical performances. The optical parameters, including the total flux, the optical efficiency, and the maximum, minimum, and mean irradiances are evaluated for ray projection simulations in the ASTM G173-03 spectrum. Experiments for the same ray source are also carried out to compare with the simulation results. It is determined that Ag-film coating can improve the profile error and surface roughness of the reflector, thus resulting in all optical parameters being either equal to or higher than those of the reflector without Ag coating. The total flux and optical efficiency obtained from the module with the Fresnel lens has values relatively higher than those of the aspheric lens. The irradiance uniformity for the Fresnel lens is also determined to be better than that of the aspheric lens. The irradiance intensity of the reflector after coating the Ag film has a magnitude at various wavelengths higher than that of the reflector without the Ag-film coating. Due to the coating of the Ag film, the optical receiver shows an almost constant rise in optical efficiency for the two types of concentrating lenses. This characteristic is shown to be valid for both the simulation and experimental results.

Sign in / Sign up

Export Citation Format

Share Document