By performing spatially resolved Raman and photoluminescence spectroscopy with different illumination conditions, we have achieved a unified understanding towards the spectroscopy signatures of the organic-inorganic h...
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By performing spatially resolved Raman and photoluminescence spectroscopy with different illumination conditions, we have achieved a unified understanding towards the spectroscopy signatures of the organic-inorganic hybrid perovskite, transforming from the pristine state (CH 3 NH 3 PbI 3 or MAPbI 3 ) to fully degraded state (i.e., PbI 2 ), for samples with varying crystalline domain size from mesoscopic scale to macroscopic size, synthesized by three different techniques.
Zinc oxide (ZnO) nanowires, sensitized with spray pyrolyzed indium sulfide, were obtained by chemical bath deposition. The XRD analysis indicated dominant evolution of hexagonal ZnO phase. Significant gain in photoele...
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In this work, foundry sands (silica source) from metal casting and oyster shells (source of calcium carbonate) wastes were collected and characterized for use as raw materials for the production of soda-lime glasses. ...
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Glass-ceramic foams belonging to the LZSA (Li2O-ZrO2-SiO2-Al2O3) system were processed as catalytic supports for the ethanol decomposition. The active phases of the support (Ni, Co) were prepared by wet impregnation. ...
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The improvement on the development of porous ceramic materials has leaded to new technologies in thermal insulation, for example, composite materials for better performance of pressure vessels in rocket engines. Withi...
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The study of new joining technologies for multimaterial structures is motivated by the environmental friendly policy of weight reduction in the automotive industry. Friction-based Injection Clinching Joining (F-ICJ) (...
The study of new joining technologies for multimaterial structures is motivated by the environmental friendly policy of weight reduction in the automotive industry. Friction-based Injection Clinching Joining (F-ICJ) (European Patent Application EP 14182938.2) is a new staking-based joining technique, which uses frictional heating to produce joints in an energy-efficient and fast manner. In F-ICJ a non-consumable tool applies friction and force to soften or melt and deform a polymeric stud fitted in a through hole of a joining partner. After consolidation, the deformed stud (stake) mechanically joins the partners by creating a staked joint. The thermomechanical process exposes the polymer to high temperatures (250 - 290°C) and deformation rates resulting from the combination of tool rotational speeds of 8000-12000 rpm and short joining cycles (5-10 seconds). Resulting changes in material properties can affect the global performance of the joints. This study aims to investigate the chemical changes occurred in the polymeric partner of hybrid joints on polyetherimide (PEI) and aluminum 6082-T6. Molecular weight distribution (Size-Exclusion Chromatography - SEC) and chemical structure (Fourier transform infrared spectroscopy – FTIR) analyses were performed on the base material and PEI extracted from a joint to evidence any possible chemical changes caused by frictional heating. The polymeric sample from the joint showed number-average molecular weight (Mn) 23% smaller and weight-average molecular weight (Mw) 15% smaller than the PEI base material. FTIR spectra show reduction in the intensity of phthalimide bands owing to the F-ICJ process. Therefore, these analyses identified the extension of chain scission in the PEI caused by shear and heat imposed by F-ICJ process, which are fundamental for process optimization.
This paper focuses on the multiscale mechanism of collapse of hemicylindrical annular surface macrocavities in steel caused by high-strain, high-strain rate plastic flow of copper. Experiments and simulations revealed...
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This paper focuses on the multiscale mechanism of collapse of hemicylindrical annular surface macrocavities in steel caused by high-strain, high-strain rate plastic flow of copper. Experiments and simulations revealed that a two-stage process is responsible for the observed microjetting phenomena: the formation of lateral copper microjets from the localized shear flow in copper at the interface during the filling of the cavity, and their subsequent collision at the apex of the macrocavity generating two additional horizontal microjets. The lengths of these microjets were an order of magnitude smaller than the cavity size but linearly scaled with the cavity radius. This process of microjet development is sensitive to the cavity geometry and is unlike the previously observed jetting phenomena in cavitation, impact crater collapse, or shock-induced cavity collapse.
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