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Plasma source by microwaves: design description; Fuente de plasma por microondas : descripcion de diseno. Directory of Open Access Journals Sweden. Oxygenated groups were introduced in the EPDM surface after treatment, even in treatments without oxygen.
Theses groups were formed when the activated surface was exposed to the atmosphere. In treatments with nitrogen, oxygenated and possible nitrogenated groups were identified by FT-IR. Several characterizations techniques were used to analize the microsctructural change, such as, optical microscopy OM, microhardness Vickers, X-Ray diffraction DRX.
The Vickers results showed a value of Hv on the top of the surface a concentration profile of microhardness is observed from the top of the surface to the core of the material. Piezas de acero AISI fueron nitruradas en un reactor experimental fabricado en el laboratorio. Scott, F. L'addition de plaques conductrices dans la region aval du miroir a pour effet d'attenuer la violence de l'instabilite en cannelures. Cette attenuation ne depend que de la resistance surfacique de ces plaques.
Les auteurs ont etudie cet effet en mesurant le spectre de frequence des signaux en provenance de sondes a sintillateur enrobe placees au voisinage de l'enceinte a vide. El plasma de 70 eV se inyecta mediante un cation en el espejo, con ayuda de un campo de gufa octopolar de tipo lineal. El campo especular se aplica durante un lapso igual al tiempo de transito del plasma. Se observan dos modos definidos de operacion, dependientes exclusivamente de las condiciones establecidas en el campo de gufa.
Segun el primer modo, en el espejo el plasma no sufre estriado alguno, la mayor parte del mismo escapa en direccion axial, se observa una lenta, y anomala difusion radial y se emiten microondas en los ar-. La emision de microondas no es compatible con la rama electronica de la inestabilidad de Harris. La estabilidad de este modo se atribuye a la union lineal por el plasma frio que sale por efusion de la zona del campo de gufa. Esta densidad disminuye al agregar al campo de gufa un cilindro de simetria axial.
El plasma resultante, atrapado en el espejo presenta inestabilidades en forma de estrias, perdidas radiales. Plasma density determination by microwave interferometry.
El interferometro de 2 mm del Tokamak TJ In this paper a description is given of the microwave interferometer used for measuring the plasma electronic density in the TJ-1 Tokamak of Fusion Division of JEN. The principles of the electronic density measurement are discussed in detail, as well as those concerning the determination of density pro files from experimental data. A description of the interferometer used in the TJ-1 Tokamak is given, together with a detailed analysis of the circuits which constitute the measuring chain.
The working principles of the klystron reflex and hybrid rings are also presented. Author 23 refs. Amostras desse material foram sinterizadas em forno convencional e de micro-ondas.
Os resultado Full Text Available This paper present the results of the synthesis and characterization of semiconductor nanoparticles of CdS by microwaves. The synthesis was carried out under controlled potency of W, with 60 seconds on or off, as well as the pH was regulated to different values: 8, 9 and Textural analysis shows the size of pore distribution narrow, as well as superficial area of AFM micrographies shown particle nanometrics, the results of X-Ray Difraction analysis probing the same.
Spectras of UV-Vis shown that nanoparticle is less according the pH used in the synthesis, affecting the band gap energy. Espumado de mezclas de silicato de sodio-wollastonita por microondas. Full Text Available The effect of the application of microwaves on the volume, porosity and thermal conductivity of sodium silicate-wollastonite mixtures was studied.
The thermal conductivities of the ceramic foams were 0. Las conductividades t. Microwave plasma for materials treatment; Plasmas de microondas para tratamiento de materiales. Camps, E. In this work it was studied and characterized a microwave discharge type Ecr using for this electric probes and optical emission spectroscopy. The characterization was carried out with the purpose of optimizing the plasma parameters and to establish a control over the same one doing so that the experiments have a greater reproducibility and a major work efficiency.
O tempo global do primeiro para o segundo ciclo de secagem foi reduzido de 15 a 37,5 para pouco mais de 10 horas, respectivamente. This research concerns a process development study focussing the application of microwaves to pulped coffee cherries production, in order to reduce the drying time and increase the industrial yield and product quality when compared to conventional drying processes.
The overall drying time was reduced from 15 to The sensory quality of the product was evaluated by the "cup test", complemented. Finalmente se comparan los resultados con los encontrados por Kim et al. Ground tire rubber was submitted to a microwaves treatment in order to promote its devulcanization, that is, the breaking of the crosslinks between the chains. The influence of the processing parameters, such as time of exposure to the microwaves and number of treatment steps, was investigated.
After the treatment, the material was characterized in terms of its thermal, by DSC, dynamic-mechanical, by DMA and rheological, by capillary rheometry, properties. In addition, the extraction of soluble fractions was made in soxhlet, to evaluate the amount of rubber that effectively was devulcanized during the microwaves treatment. The devulcanization treatment showed to be a viable method to produce a material which can be molded, in a similar way to virgin rubber.
However, the complete devulcanization of the material was not possible in any devulcanization condition. Microwaves polymerization is a new method to design individual ocular prostheses; however, there is a lack of studies exploring the effectiveness of present method to determine the effect of the microwaves polymerization in relation to effectiveness of individual ocular prostheses rehabilitation.
An economic evaluation study was conducted to minimize costs. The simplified traditional polymerization was compared with microwaves polymerization method. For residual monomer the effectiveness transverse deflection, linear contraction, porosity, color.
Vulcanized elastomers are materials commonly used in several applications, such as automotive and footwear industries. In this study, scraps of ethylene-propylene-diene terpolymer EPDM-r from the automotive industry were exposed to microwaves during different periods min. After devulcanization, the samples were characterized by gel content, differential scanning calorimetry DSC and activation energy of degradation Ea determined by thermogravimetric analysis TGA.
The degradation behavior of EPDM-r was consistent with the literature. The gel content analysis showed that the EPDM-r was devulcanized only at 5 minutes of exposure to the microwaves.
DSC analysis demonstrated no significant changes in the samples, and the Ea results confirmed that the additives found in the composition of the EPDM-r affect the efficiency of the regeneration method. Secado de piezas de porcelana mediante microondas. Full Text Available During conventional drying, parts are heated from the outside creating large humidity and temperature gradients which, in turn, generate stresses due to differential shrinking of the part promoting their fracture. Besides, this process is very lenghty creating two important bottlenecks in the production of porcelain parts: drying and storage before refining and biscuit firing.
Microwave technology can solve these problems since parts are heated more homogenously and very quickly with smaller humidity and thermal gradients and, thus, shorter drying times and fewer rejects.
Probably the main problem in microwave drying of these products is the need to dry simultaneously parts with very different sizes, weights, thicknesses and geometries. This paper describes microwave drying of porcelain parts both individually and mixing diferent parts simultaneously. The results obtained indicate that drying times can be reduced drastically and that parts with diferent geometries and sizes do not pose a problem. Besides, the economic benefits that can be derived by introducing microwave technology in the drying process of porcelain parts are estimated.
Durante el secado convencional, las piezas se calientan desde el exterior dando lugar a elevados gradientes de humedad y temperatura que, a su vez, generan tensiones como consecuencia de contracciones diferenciales de la pieza facilitando su fractura.
Probablemente el mayor problema del secado por microondas de este tipo de productos consiste en la necesidad de secar simult. Full Text Available Metallurgical cokes are composed of graphitic carbon s2p2 and different inorganic compounds with very different capacities to absorb microwave radiation. Moreover, due to the electric conductivity shown by the metallurgical cokes, microwave radiation produces electric arcs or microplasmas, which gives rise to hot spots.
Therefore, when these cokes are irradiated with microwaves some parts of the particle experiment a rapid heating, while some others do not heat at all. As a result of the different expansion and stress caused by thermal the shock, small cracks and micro-fissures are produced in the particle.
The weakening of the coke particles, and therefore an improvement of its grindability, is produced. This paper studies the microwave-assisted grinding of metallurgical coke and evaluates the grinding improvement and energy saving. In this work we showed the polyurethane rigid foams synthesis using a macropolyol synthesized from castor oil and polyglycerol. The effect of microwaves on the reactions was.
The experimental results were adjusted based on first-order kinetic model. The activation energies in the range of The kinetic parameters obtained allow one to predict by simulation the first-order kinetic constant achieved with P. Properties of hydrogenated amorphous silicon a-Si:H deposited using a microwave Ecr plasma ; Propiedades del a-Si:H depositado utilizando un plasma de microondas.
Hydrogenated amorphous silicon a-Si:H films have been widely applied to semiconductor devices, such as thin film transistors, solar cells and photosensitive devices. The Ecr plasma was generated by microwaves at 2. Optical gaps were obtained by spectrophotometry. Decreasing temperature, optical gap values increase from 1. Visando minimizar esse problema, foram testados quatro procedimentos aplicados a diferentes amostras de solos. Four procedures were applied to certified soil samples in an attempt to circumvent this problem.
The most efficient procedure was based on microwave-assisted acid digestion decomposition of the samples, followed by separation of the residual silicate compounds. This fraction was solubilized using. Full Text Available The results obtained in the preparation of hydrotalcite-like compounds using microwave radiation are reported. The results obtained by the microwave-hydrotermal method have been compared with the conventional-hydrotermal one.
A working protocol, which allows us to obtain reproducible results, has been elaborated, and this is a new aspect in the synthesis of inorganic solids.
Hydrotalcite-like compounds with the desirable chemical composition were obtained. The cristallinity depends on the microwave radiation exposure time in all cases. Materials prepared using microwave radiation exhibit a better grain size homogeneity and a good crystalline degree and it also influences over the water molecules arrangement in the solid.
Microondas diatermia equipo de terapia para el centro de rehabilitación
Ana Claudia R. Barboza, Camila V. Cruz, Marcelo B. Graziani, Myrian C. The microwave oven became a common domestic equipment, due mainly to the short time spent to heat foods.
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