scholarly journals Effect of Sand Base Grade and Density of Moulding Sands with Sodium Silicate on Effectiveness of Absorbing Microwaves

2016 ◽  
Vol 16 (3) ◽  
pp. 103-108
Author(s):  
M. Stachowicz
Keyword(s):  
Relative Density ◽  
Sodium Silicate ◽  
Microwave Power ◽  
Power Loss ◽  
Electromagnetic Waves ◽  
Slot Line ◽  
Absorbed Power ◽  
High Silica ◽  
Sand Base ◽  
Reflected Power

Abstract In the paper, presented is a research on effectiveness of absorbing electromagnetic waves at frequency 2.45 GHz by unhardened moulding sands prepared of three kinds of high-silica base and a selected grade of sodium silicate. Measurements of power loss of microwave radiation (Pin) expressed by a total of absorbed power (Pabs), output power (Pout) and reflected power (Pref) were carried-out on a stand of semiautomatic microwave slot line. Values of microwave power loss in the rectangular waveguide filled with unhardened moulding sands served for determining effectiveness of microwave heating. Balance of microwave power loss is of technological and economical importance for manufacture of high-quality casting moulds and cores of various shapes and sizes. It was found that relative density influences parameters of power output and power reflected from samples of moulding sand placed in a waveguide. Absorption expressed by the parameter Pabs is not related to granularity of high-silica base: fine, medium and coarse. It was found that the semiautomatic microwave slot line supports evaluation of effectiveness of microwave absorption on the grounds of power loss measurements and enables statistic description of influence of relative density of the sandmix on penetration of electromagnetic waves in unhardened moulding sands.

The working standard of the unit of power of electromagnetic waves in the frequency range from 37,5 to 220 GHz

2020 ◽  
pp. 53-58
Author(s):  
A. V. Koudelny ◽  
I. M. Malay ◽  
V. A. Perepelkin ◽  
I. P. Chirkov
Keyword(s):  
Microwave Power ◽  
Electromagnetic Waves ◽  
Primary Standard ◽  
The State ◽  
Frequency Range ◽  
Working Standard ◽  
Extended Frequency Range ◽  
Effective Efficiency ◽  
Extended Frequency ◽  
Good Agreement

The possibility of using bolometric converters of microwave power from the State primary standard of the unit of power of electromagnetic waves in waveguide and coaxial paths GET 167-2017, which has a frequency range from 37,5 to 78,33 GHz, in an extended frequency range up to 220 GHz, is shown. Studies of semiconductor bolometric converters of microwave power in an extended frequency range have confirmed good agreement and smooth frequency characteristics of the effective efficiency factor of the converters. Based on the research results, the State working standard of the unit of power of electromagnetic waves of 0,1–10 mW in the frequency range from 37,5 to 220 GHz 3.1.ZZT.0288.2018 was approved. The technical characteristics of the working standard of the unit of power of electromagnetic oscillations in an extended frequency range from 37,5 to 220 GHz are given.

scholarly journals Unconventionally Made-Cellular Glass Aggregate

2021 ◽  
Vol 2 (6) ◽  
pp. 21-31
Author(s):  
Lucian Paunescu ◽  
Sorin Mircea Axinte ◽  
Felicia Cosmulescu
Keyword(s):  
Calcium Carbonate ◽  
Sodium Silicate ◽  
Electromagnetic Waves ◽  
Microwave Field ◽  
Industrial Processes ◽  
Sodium Borate ◽  
Residual Glass ◽  
Cellular Glass ◽  
Glass Aggregate ◽  
Fluxing Agent

Improving the original manufacturing process in microwave field of a cellular glass aggregate using a recipe containing colored consumed drinking bottle, calcium carbonate (CaCO3) as an expanding agent, sodium borate (borax) as a fluxing agent and sodium silicate (Na2SiO3) as a binder is shown in the work. The main adopted technological measures were the advanced mechanical processing of residual glass at a grain dimension below 100 μm and especially the use of a high electromagnetic wave susceptible ceramic tube with a wall thickness reduced from 3.5 to 2.5 mm for the protection of the pressed glass-based mixture against the aggressive effect of microwave field and, in the same time, to achieve a preponderantly direct heating with electromagnetic waves. Of the tested variants, a recipe with 1.6 % calcium carbonate, 6 % borax, 8 % sodium silicate and the rest residual glass was determined to be optimal. The cellular glass aggregate had the bulk density of 0.22 g/cm3, heat conductivity of 0.079 W/m·K and compression strength of 5.9 MPa. The specific consumption of energy was very low (0.71 kWh/kg) below the range of reported values of the industrial processes consumption (between 0.74-1.15 kWh/kg).  

scholarly journals Electron cyclotron converters of microwaves in wireless power transmission systems

2020 ◽  
Vol 21 (4) ◽  
pp. 254-259
Author(s):  
Yury A. Pirogov ◽  
Gohar M. Kazaryan ◽  
Vladimir L. Savvin
Keyword(s):  
Microwave Power ◽  
Electromagnetic Waves ◽  
Power Plants ◽  
Power Transmission ◽  
Electrical Energy ◽  
Electron Cyclotron ◽  
Stable Operation ◽  
The Earth ◽  
Satellite Platform ◽  
Power Transmission Systems

A proposal to use special electron cyclotron devices as effective converters of electromagnetic waves into direct current in modern microwave systems for wireless transmission of electrical energy to the Earth via a microwave channel from solar space power plants located on board geostationary satellites is considered. Such converters are a product of domestic development, they can have a conversion efficiency of more than 80%, they are insensitive to overloads and are several orders of magnitude more economical than the well-known semiconductor rectennas (rectifying antennas). Semiconductor rectennas, assembled from a multitude of individual semiconductor diodes with a Schottky barrier, in the process of nonlinear conversion of microwaves, generate parasitic radiation that forms a powerful electromagnetic background, which seriously interferes with the stable operation of information systems of special and general civil communications. In addition, the cost of semiconductor rectennas is several orders of magnitude higher than that of electron-cyclotron converters with the same input microwave power. Due to the high compactness of the electronic converters, they can also be installed on an intermediate satellite platform in the stratosphere, receiving the energy of the Sun through a laser beam from a geostationary orbit and transmitting it to the Earth with practically no loss through the microwave channel. The possibilities of using electron cyclotron converters in ground-based systems for wireless energy transmission are also promising. Already the first electron cyclotron converters, created at the Torii enterprise according to the project of the Lomonosov Moscow State University, had an efficiency of over 60% at an input microwave power of 10 kW.

Microwave power loss and XPS measurements on high Tc NdBaCuOxide superconducting system

1988 ◽  
Vol 66 (4) ◽  
pp. 409-411 ◽  
Author(s):  
B. Viswanathan ◽  
R. Raman ◽  
N.S. Raman ◽  
V.R.K. Murthy
Keyword(s):  
Microwave Power ◽  
Power Loss ◽  
High Tc

The Effect of Solid-to-Liquid Ratio and Temperature on Mechanical Properties of Kaolin Geopolymer Ceramics

2015 ◽  
Vol 660 ◽  
pp. 23-27 ◽  
Author(s):  
Romisuhani Ahmad ◽  
Mohd Mustafa Al Bakri Abdullah ◽  
Kamarudin Hussin ◽  
Andrei Victor Sandu ◽  
Mohammed Binhussain ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Powder Metallurgy ◽  
Flexural Strength ◽  
Relative Density ◽  
Sodium Silicate ◽  
Sintered Sample ◽  
Liquid Ratio ◽  
Naoh Solution ◽  
Sample Range ◽  
Alkaline Activator

The effect of solid-to-liquid ratio and temperature on the mechanical properties of kaolin geopolymer ceramics are studied. Kaolin and alkaline activator were mixed with the solid-to-liquid ratio in the range of 0.8-1.2. Alkaline activator was formed by mixing the 12 M NaOH solution with sodium silicate at a ratio of 0.24. Kaolin geopolymer ceramic have been produced by using powder metallurgy (PM) technique. The samples were heated at different temperature started from 900 °C until 1200 °C and the strength were tested. The relative density and flexural strength of sintered sample range approximately 84%-95% and 20-90 MPa respectively. The result revealed that the optimum flexural strength was obtained at solid-to-liquid ratio of 1.0 and the samples heated at 1200 °C achieved the highest flexural strength (90 MPa).

scholarly journals Power loss density of electromagnetic waves in unimolecular reactions

RSC Advances ◽  
2017 ◽  
Vol 7 (43) ◽  
pp. 26546-26550 ◽  
Author(s):  
Yinhong Liao ◽  
Sanmei Zhang ◽  
Zhengming Tang ◽  
Xinpeng Liu ◽  
Kama Huang
Keyword(s):  
Chemical Reactions ◽  
Power Loss ◽  
Electromagnetic Waves ◽  
Unimolecular Reactions ◽  
Microwave Assisted

Microwave-assisted chemical reactions have been widely used, but the mechanism is still unclear, which limits further applications.

scholarly journals Evaluation of the Possibilities of Sodium Silicate Sands Application in Automated Hot-Box Process of Cores Shooting

2017 ◽  
Vol 17 (4) ◽  
pp. 155-160
Author(s):  
M. Stachowicz ◽  
K. Granat ◽  
P. Obuchowski
Keyword(s):  
Sodium Silicate ◽  
Bending Strength ◽  
Heating Temperature ◽  
Heating Time ◽  
Silica Matrix ◽  
Silica Sand ◽  
Operating Parameters ◽  
High Quality ◽  
High Silica ◽  
Preliminary Research

AbstractThe paper presents the results of preliminary research on the use of silica sands with hydrated sodium silicate 1.5% wt. of binder for the performance of eco-friendly casting cores in hot-box technology. To evaluate the feasibility of high quality casting cores performed by the use of this method, the tests were made with the use of a semiautomatic core shooter using the following operating parameters: initial shooting pressure of 6 bar, shot time 4 s and 2 s, core-box temperature 200, 250 and 300 °C and core heating time 30, 60, 90 and 150 s. Matrixes of the moulding sands were two types of high-silica sand: fine and medium. Moulding sand binder was a commercial, unmodified hydrated sodium silicate having a molar module SiO2/ Na2O of 2.5. In one shot of a core-shooter were made three longitudinal samples (cores) with a total volume of about 2.8 dm3. The samples thus obtained were subjected to an assessment of the effect of shooting parameters, i.e. shooting time, temperature and heating time, using the criteria: core-box fill rate, bending strength (RgU), apparent density and surface quality after hardening. The results of the trials on the use of sodium silicate moluding sands made it possible to further refine the conditions of next research into the improvement of inorganic warm-box / hot-box technology aimed at: reduction of heating temperature and shot time. It was found that the performance of the cores depends on the efficiency of the venting system, shooting time, filling level of a shooting chamber and grains of the silica matrix used.

Energy Absorption in Gold Nanoshells

2013 ◽  
Vol 23 ◽  
pp. 74-82 ◽  
Author(s):  
C.H. Liu ◽  
B.Q. Li
Keyword(s):  
Energy Absorption ◽  
Electromagnetic Waves ◽  
Strong Field ◽  
Structural Parameters ◽  
Particle Surface ◽  
Field Enhancement ◽  
Absorption Efficiency ◽  
Skin Depth ◽  
Surface Plasma Resonance ◽  
Absorbed Power

A modeling study on energy absorption and transport in an isolated nanoshell and aggregates of nanoshells under localized surface plasma resonance (SPR) conditions is presented. A comprehensive model for multi-scattering of electromagnetic waves by a cluster of multilayered nanoshells is developed, which applies the Wigner-Eckart theorem for the calculation of the total scattering cross sessions of nanoshell aggregates. Absorption by an isolated nanoshell and by nanoshell clusters is studied using the model. Results show that the inter-nanoshell coupling results in strong field enhancement near the particle surface. Energy absorption in a nanoshell can be tuned by varying the structural parameters of the nanoshell. Smaller particles are more absorbing than the large ones, other conditions being equal. Because of the presence of a dielectric cavity, the radial distribution of the absorbed power in the metal shell may differ from the classical skin depth phenomena. The interaction among particles in close proximity causes the energy absorption efficiency and the resonance position of a nanoshell cluster to differ from those of an isolated nanoshell.

scholarly journals Effect of Temperature on Chromite-Based Moulding Sands Bonded with Sodium Silicate

2017 ◽  
Vol 17 (2) ◽  
pp. 95-100
Author(s):  
M. Stachowicz ◽  
M. Kamiński ◽  
K. Granat ◽  
Ł. Pałyga
Keyword(s):  
Iron Oxide ◽  
Sodium Silicate ◽  
Elevated Temperatures ◽  
Thermal Action ◽  
Magnesium Content ◽  
Effect Of Temperature ◽  
Eds Analysis ◽  
Moulding Sand ◽  
Sand Base ◽  
Hardness Values

Abstract In the paper, a research on effects of baking temperature on chromite sand base of moulding sands bonded with sodium silicate is presented. Pure chromite sand and its chromite-based moulding sand prepared with use of sodium silicate were subjected to heating within 100 to 1200 °C. After cooling-down, changes of base grains under thermal action were determined. Chromite moulding sand was prepared with use of 0.5 wt% of domestic made, unmodified sodium silicate (water-glass) grade 145. After baking at elevated temperatures, creation of rough layer was observed on grain surfaces, of both pure chromite sand and that used as base of a moulding sand. Changes of sand grains were evaluated by scanning microscopy and EDS analyses. It was found that changes on grain surfaces are of laminar nature. The observed layer is composed of iron oxide (II) that is one of main structural components of chromite sand. In order to identify changes in internal structure of chromite sand grains, polished sections were prepared of moulding sand hardened with microwaves and baked at elevated temperatures. Microscopic observations revealed changes in grains structure in form of characteristically crystallised acicular particles with limited magnesium content, intersecting at various angles. EDS analysis showed that these particles are composed mostly of chromium oxide (III) and iron oxide (II). The temperature above that the a.m. changes are observed in both chromite-based moulding sand and in pure chromite sand. The observed phenomena were linked with hardness values and mass of this sand.

Sign in / Sign up

Export Citation Format

Share Document