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Calix-Assisted Fabrication of Metal Nanoparticles
Published in Klaus D. Sattler, st Century Nanoscience – A Handbook, 2019
Anita R. Kongor, Manthan K. Panchal, Vinod K. Jain, Mohd Athar
The technique of arc discharge has received considerable interest with the exploration of novel methods to synthesize nanoparticles (Shi et al. 1999, Zhou et al. 1999). In this method, the word arc refers to luminous electrical discharge in the shape of “arc” between two electrodes. The arc discharge takes place due to electrical breakdown of a gas when current is applied between two electrodes, resulting in the discharge of plasma. The product depends on the voltage and current applied to the electrode and the material used as cathode/anode. Thus, arc discharge method presents the production of nanoparticles due to arc-assisted breakdown of bulk materials. A high yield of product is difficult to achieve using this method and requires careful control of the experimental conditions.
Environmental mitigation and pollution control technologies
Published in Anjan Kumar Chatterjee, Cement Production Technology, 2018
The operational principle is shown schematically in Figure 9.7. When a potential gradient is established in the gas between a thin wire and the parallel plates, ionization of gas molecules takes place. The electrical breakdown or ion discharge is known as “corona discharge,” which transforms the gas from insulating to conducting state. Corona discharge can either be positive or negative. Negative corona is the most suitable for industrial use as most of the gases are electron-negative in nature. In ESPs using negative corona, the discharge and collecting electrodes act as negative and positive (earthed) electrodes, respectively. After gas ionization, negative ions collide with the dust particles, transfer the charge, and cause them to migrate towards the collecting electrode. The positive ions move towards the discharge electrode.
Drastic Improvement of Dielectric Performances by Nanocomposite Technology
Published in Toshikatsu Tanaka, Takahiro Imai, Advanced Nanodielectrics, 2017
Muneaki Kurimoto, Kazuyuki Tohyama, Yasuhiro Tanaka, Yoshinobu Mizutani, Toshikatsu Tanaka, Masayuki Nagao, Naoki Hayakawa, Takanori Kondo, Tsukasa Ohta
When the intensity of an electric field applied to an insulator exceeds a certain value, the current passing through the insulator abruptly increases to nearly infinity, resulting in electrical breakdown. For solids, heat is generated upon electrical breakdown, causing the materials to irreversibly burn out. Thus, electrical breakdown can be a factor that determines the lifetime of insulators. Therefore, breakdown characteristics are one of the important characteristics of insulators, and the clarification of these characteristics and the breakdown phenomenon has been a target of research. Electrical breakdown that occurs in a short period and its characteristics are important in designing insulators with various performance characteristics, such as the withstand voltage (measured in insulation tests on devices using insulators) and robustness against voltage surges caused by lightning or switching events.
Degradation patterns of silicone-based dielectric elastomers in electrical fields
Published in International Journal of Smart and Nano Materials, 2018
Liyun Yu, Frederikke B. Madsen, Anne L. Skov
Electrical breakdown may occur through thermal breakdown mechanisms, i.e. heating takes place locally and the heating results in increased conductivity which then again leads to further Joule heating. Thus an accelerating coupling arises since conductivity scales exponentially with temperature. The heating may lead to instantaneous breakdown due to an increased field but may also a priori lead to degradation of the elastomer and thus loss of mass, which then subsequently leads to electro-mechanical breakdown due to decreased thickness. When the elastomer starts degrading it may even experience reduced mechanical properties locally in such a way that the elastomer collapses mechanically. With these scenarios in mind the thermal breakdown patterns are investigated in order to elucidate at which temperatures the elastomers degrade in a nitrogen atmosphere (which is assumed a comparable atmosphere to that of a dielectric elastomer sealed within metallic electrodes).
A computational model of bio-inspired tunable lenses
Published in Mechanics Based Design of Structures and Machines, 2018
Q. Wang, Y. J. Cao, Y. N. Wang, J. C. Liu, Y.-X. Xie
There are three failure modes of DE film including tension loss, tensile fracture and electrical breakdown. Tension loss is caused by over pre-stretching that induces electroluminescent deformation of the DE film, leading to inner stress disappearance and failure to maintain geometrical shape of the film. Tensile fracture happens when the DE film is stretched over its maximum stretch limit. Electrical breakdown happens when the electric field intensity is over the limit and high voltage produces a conductive path by driving the charged particles to move in the film. Therefore, to ensure safe and effective application of the lens, the electric field intensity, stress and strain in the lens as well as actuator in the working condition need to be analyzed.