scholarly journals Behaviour of Microwave-Heated Al4SiC4 at 2.45 GHz

Materials ◽  
2021 ◽  
Vol 14 (17) ◽  
pp. 4878
Author(s):  
Takashi Fujii ◽  
Akio Oshita ◽  
Keiichiro Kashimura
Keyword(s):  
Microwave Heating ◽  
Physical Property ◽  
Single Mode ◽  
Dielectric Constants ◽  
Energy Concentration ◽  
Microwave Absorbers ◽  
High Temperature Processes ◽  
Powder Samples ◽  
Higher Temperature ◽  
Electrical Permittivity

The ongoing development of high-temperature processes with the use of microwaves requires new microwave absorbers that are useful at these temperatures. In this study, we propose Al4SiC4 powders as important and efficient microwave absorbers. We investigated both the behavioural microwave heating and electrical permittivity characteristics of Al4SiC4 powders with various particle sizes at 2.45 GHz. The TE103 single-mode cavity indicated that Al4SiC4 powder samples yielded different heating behaviours and dielectric constants for each particle size compared with SiC. By microwave heating ∅50 mm × 5 mm disks of Al4SiC4 and SiC, we demonstrate that for specific sizes, Al4SiC4 can be heated at a higher temperature than SiC. Finally, the results of the two-dimensional two-colour thermometer show that an energy concentration appears at the interface of the microwave-heated Al4SiC4. These phenomena, which are inconsistent in individual physical property values, can be explained without contradicting microwave heating physics.

Technique for Measuring the Dielectric Properties of Minerals as a Function of Temperature and Density at Microwave Heating Frequencies

1990 ◽  
Vol 189 ◽  
Author(s):  
Johanna B. Salsman
Keyword(s):  
Dielectric Properties ◽  
Microwave Heating ◽  
Research Effort ◽  
Coaxial Line ◽  
Dielectric Constants ◽  
Dielectric Constant And Loss ◽  
Electrical Conductivities ◽  
Natural Density ◽  
The Common ◽  
Method Of Measurement

ABSTRACTAs part of the research effort on investigating the effects of microwave energy absorption on the chemical and physical properties of minerals and ores, the Bureau of Mines, Tuscaloosa Research Center has developed a technique of measuring the dielectric constant and loss tangent of minerals at the common microwave heating frequencies. The objective was to establish a reliable data base to aid in predicting the effects of microwave heating on minerals.In this phase of microwave research, the Bureau measured the dielectric properties of powdered minerals with medium to high electrical conductivities (a ≥ 0.02 Mho/m) in the frequency range of 300 MHz to 3 GHz using an open-ended coaxial line probe connected to an HP 8753A network analyzer. Since the minerals were prepared as powders, techniques were used to relate the measured dielectric properties of the powdered minerals to the dielectric properties of the mineral at Its theoretical or natural density. Also, these measurements were performed as a function of temperature, from 25° to 325° C.The measured values of the dielectric constants and loss tangents using this method were accurate within ±5 percent. This report describes the method of measurement and discusses the results of the Bureau's investigations into dielectric properties of minerals.

Application of microwave heating to ceramic processing: Design and initial operation of a 2.45-GHz single-mode furnace

1996 ◽  
Vol 24 (3) ◽  
pp. 1041-1049 ◽  
Author(s):  
A.W. Fliflet ◽  
R.W. Bruce ◽  
A.K. Kinkead ◽  
R.P. Fischer ◽  
D. Lewis ◽  
...  
Keyword(s):  
Microwave Heating ◽  
Single Mode ◽  
Ceramic Processing ◽  
Initial Operation

scholarly journals Analysis of Propagation Characteristics along an Array of Silver Nanorods Using Dielectric Constants from Experimental Data and the Drude-Lorentz Model

Electronics ◽  
2019 ◽  
Vol 8 (11) ◽  
pp. 1280 ◽  
Author(s):  
Zong ◽  
Zhang
Keyword(s):  
Experimental Data ◽  
Propagation Constant ◽  
Single Mode ◽  
Expansion Method ◽  
Dielectric Constants ◽  
Fourier Series Expansion ◽  
Lorentz Model ◽  
Silver Nanorods ◽  
Complex Propagation ◽  
Multi Mode

In this study, the Fourier series expansion method (FSEM) was employed to calculate the complex propagation constants of plasma structures consisting of infinitely long, silver nanorod arrays in the range of 180–1900 nm, and the characteristics of the complex propagation constant were analyzed in depth. According to the results of FSEM using dielectric constants from Johnson experimental data, a multi-mode frequency band appears in the propagation stage, which can be adopted to achieve a multi-mode communication, multi-mode transceiver, integrated filter with single multi-mode combination. In the meantime, the comparison between the three sets of results with only single mode transmission of the generalized multipole technique (GMT) using dielectric constants from Johnson experimental data, FSEM using dielectric constants from Palik experimental data, and FSEM using dielectric function from Drude–Lorentz model suggested that the results of the four sets of complex propagation constants were well consistent with each other. Furthermore, a finite array of only 40 silver nanorods was studied, and the ability of guided waves when a finite array is excited by a plane wave at a specific wavelength was explored. According to different guiding abilities—propagation, attenuation, and cut off, it can be applied to waveguides, sensor, filters, etc.

scholarly journals Electrical Conductivity Studies on Co(II), Cu(II),Ni(II) and Cd(II) Complexes of Azines

2008 ◽  
Vol 5 (4) ◽  
pp. 797-801 ◽  
Author(s):  
M. Revanasiddappa ◽  
Syed Khasim ◽  
S. C. Raghavendra ◽  
C. Basavaraja ◽  
T. Suresh ◽  
...  
Keyword(s):  
Room Temperature ◽  
Molar Conductance ◽  
Molar Ratio ◽  
Temperature Conductivity ◽  
Physical Methods ◽  
Alcoholic Medium ◽  
Electrical Conductivities ◽  
Powder Samples ◽  
Higher Temperature ◽  
Uv Visible

1-Phenyl-4-(2'-hydroxyphenyl-1-yl)di-imino azine, {1P-4-(2' HPDA)} 1, 4(2'-hydroxyphenyl-1-yl)di-imino azine, {1, 4-(2' HPDA)} are derived from benzophenone hydrozone with different aldehydes in presence of few drops of concentrated hydrochloric acid in alcoholic medium. Metal(II) complexes have been prepared by salts of CoCl2, CuCl2, NiCl2and CdCl2reacting with azine ligands dissolved in alcohol in the molar ratio of (1:2). The prepared complexes were characterized by using various physical methodsviz. elemental, molar conductance, magnetic susceptibility, IR, NMR, XRD and UV-Visible. Conductivity of the powder samples were measured by two probe method. Measured electrical conductivities of Co(II), Cu(II), Ni(II) and Cd(II) complexes of azines are reported in this paper. It is found that at room temperature these complexes show insulator behavior. At higher temperature conductivity increases linearly, showing semi conducting behavior.

Transient Temperature Distributions in a Cylinder Heated by Microwaves

1996 ◽  
Vol 430 ◽  
Author(s):  
H. W. Jackson ◽  
M. Barmatz ◽  
P. Wagner
Keyword(s):  
Numerical Solutions ◽  
Single Mode ◽  
Dielectric Constants ◽  
Microwave Cavity ◽  
Transient Temperature ◽  
Hybrid Heating ◽  
Fine Mesh ◽  
Temperature Distributions ◽  
Analytic Expressions ◽  
Lossy Dielectric

AbstractTransient temperature distributions were calculated for a lossy dielectric cylinder coaxially aligned in a cylindrical microwave cavity excited in a single mode. Results were obtained for sample sizes that range from fibers to large cylinders. Realistic values for temperature dependent complex dielectric constants and thermophysical properties of the samples were used. Losses in cavity walls were taken into account as were realistic thermal emissivities at all surfaces. For a fine mesh of points in time, normal mode properties and microwave power absorption profiles were evaluated using analytic expressions. Those expressions correspond to exact solutions of Maxwell's equations within the framework of a cylindrical shell model. Heating produced by the microwave absorption was included in self-consistent numerical solutions of thermal equations. In this model, both direct microwave heating and radiant heating of the sample (hybrid heating) were studied by including a lossy dielectric tube surrounding the sample. Calculated results are discussed within the context of two parametric studies. One is concerned with relative merits of microwave and hybrid heating of fibers, rods, and larger cylinders. The other is concerned with thermal runaway.

Validation of measured microwave absorption and temperature change for development of a single-mode-type microwave heating thermogravimetry apparatus

2017 ◽  
Vol 88 (2) ◽  
pp. 024101 ◽  
Author(s):  
Achmad Dwitama Karisma ◽  
Taishu Hamaba ◽  
Tomonori Fukasawa ◽  
An-Ni Huang ◽  
Tomoomi Segawa ◽  
...  
Keyword(s):  
Microwave Heating ◽  
Microwave Absorption ◽  
Temperature Change ◽  
Single Mode

Materials processed by indirect microwave heating in a single-mode cavity

2006 ◽  
Vol 32 (8) ◽  
pp. 911-915 ◽  
Author(s):  
D. Grossin ◽  
S. Marinel ◽  
J.-G. Noudem
Keyword(s):  
Microwave Heating ◽  
Single Mode ◽  
Single Mode Cavity

Phase transformations in Si-based alloy powder mixtures induced by microwave heating in a 2.45 GHz single-mode applicator

2010 ◽  
Vol 18 (11) ◽  
pp. 2030-2033 ◽  
Author(s):  
Song Li ◽  
Guoqiang Xie ◽  
Dmitri V. Louzguine-Luzgin ◽  
Ziping Cao ◽  
Noboru Yoshikawa ◽  
...  
Keyword(s):  
Phase Transformations ◽  
Microwave Heating ◽  
Alloy Powder ◽  
Single Mode ◽  
Powder Mixtures

Metallurgical and Chemical Applications of Intermetallics

MRS Bulletin ◽  
1996 ◽  
Vol 21 (5) ◽  
pp. 37-43 ◽  
Author(s):  
Jack H. Westbrook
Keyword(s):  
Physical Property ◽  
Recovery Process ◽  
Second Century ◽  
Solid Gold ◽  
Process Metallurgy ◽  
Key Factor ◽  
Higher Temperature ◽  
Bronze Mirrors ◽  
Constituent Elements ◽  
Metallurgical Processes

Practical metallurgical application of intermetallic compounds (IMCs) occurred more than 3,000 years before they were recognized as distinct entities in alloys. Pliny, The Elder (A.D. 23–79) recorded in his encyclopedia a then old practice: the use of mercury both to recover gold from sands and other dispersed sources, and to gild less-noble metal objects. In both cases, the key factor is the formation of a Au-Hg intermetallic compound (amalgam) stable at room temperature but readily decomposable on heating to produce solid gold. An illustration of the Au-recovery process, reproduced from Ercker (1574) appears in Figure 1. Use of the amalgam processes for silver apparently occurred later. Bronze mirrors were silver-coated with the amalgam process by the Chinese in the second century B.C., and silver was recovered from crushed sulfide ores using mercury in the famous Potosi process (1566, but probably known much earlier).The key properties of intermetallics that make possible their diverse applications in chemical and metallurgical processes are their high melting points relative to one or all of their constituent elements, their often sharply defined composition, their brittleness, and their controllable reactivity/stability–that is, systems can be chosen such that a stable intermetallic forms easily at room or low temperatures that is nonetheless readily decomposable at a higher temperature. Once the intermetallic forms however, a useful physical property (e.g., hardness or conductivity) or chemical property (oxidation, sulfidation, corrosion resistance, nonsticking quality, etc.) may be that which is ultimately exploited in use.We will review these two classes of applications using representative examples from both process metallurgy and chemistry.

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