Characterization of Sintered Reaction-Bonded Silicon Nitride Processed by Microwave Heating

1992 ◽  
Vol 269 ◽  
Author(s):  
J. O. Kiggans ◽  
T. N. Tiegs
Keyword(s):  
Silicon Nitride ◽  
Microwave Heating ◽  
Microwave Processing ◽  
Conventional Heating ◽  
Processed Material

ABSTRACTSintered reaction-bonded silicon nitride (SRBSN) tiles were fabricated using microwave and conventional heating. Materials from both processes were analyzed at various stages in their fabrication. Microwave processing resulted in a SRBSN material of higher density and strength than the conventionally processed material.

Microwave Processing of Silicon Nitride

1990 ◽  
Vol 189 ◽  
Author(s):  
T. N. Tiegs ◽  
J. O. Kiggans ◽  
H. D. Kimrey
Keyword(s):  
Silicon Nitride ◽  
Grain Boundary ◽  
Microwave Heating ◽  
Grain Growth ◽  
Microwave Power ◽  
Microwave Sintering ◽  
Microwave Processing ◽  
Microwave Furnace

ABSTRACTMicrowave sintering of Si3N4—based materials showed improved densification as compared to samples heated conventionally under similar conditions. Accelerated nitridation of Si in the microwave furnace to produce Si3N4 was also observed. Dense Si3N4, annealed by microwave heating, exhibited enhanced grain growth; however preferential coupling of the microwave power to the grain—boundary phases in the present experiments resulted in their degradation.

Microstructural Investigation and Characterization of Bulk Brass Melted by Conventional and Microwave Processing Methods

2017 ◽  
Vol 890 ◽  
pp. 356-361 ◽  
Author(s):  
Lingappa M. Shashank ◽  
M.S. Srinath ◽  
Hassan Jayaraj Amarendra
Keyword(s):  
Microwave Processing ◽  
Microwave Oven ◽  
Conventional Heating ◽  
Metallic Materials ◽  
X Ray Diffraction ◽  
Microstructural Investigation ◽  
Xrd Pattern ◽  
X Ray ◽  
Domestic Microwave Oven

Microwave processing of bulk metallic materials is an emerging area. In the present work, brass in bulk form is melted in a modified domestic microwave oven operating at 2.45 GHz frequency. As-received and the as-cast brass are subjected to metallurgical and mechanical characterization. Specimens’ surface morphology is studied under Scanning Electron Microscope (SEM). X-Ray Diffraction (XRD) pattern shows the presence of copper oxides phase in both cast brass. Average tensile strength of brass melted using microwave oven is found higher when compared with brass melted in muffle furnace. Hardness of the as-cast brass is found to be higher than the as-received brass. However, brass cast by microwave irradiation exhibits around 2 % higher hardness than the brass cast by conventional heating. Microwave melting of brass consumed nearly six times less time compared to conventional melting.

Nitridation of Non-Isothermal Silicon Compacts

1992 ◽  
Vol 269 ◽  
Author(s):  
Jeffrey J. Thomas ◽  
Renee R. Jesse ◽  
D. Lynn Johnson ◽  
Hamlin M. Jennings
Keyword(s):  
Silicon Nitride ◽  
Temperature Gradient ◽  
Microwave Heating ◽  
Reaction Rate ◽  
Conventional Heating

ABSTRACTThe use of microwave heating for the processing of reaction-bonded silicon nitride offers at least two advantages over conventional heating methods. First, the reaction can be made to proceed preferentially in the interior of the reacting compact by maximizing the temperature gradient resulting from microwave heating. This helps maintain the flow of nitrogen into the compact during the later stages of the reaction, when the overall porosity is reduced. Second, the reaction rate can be controlled by changing the power, which gives better control over the processing than can be obtained using conventional heating.

scholarly journals Microwave Heating Improvement: Permittivity Characterization of Water–Ethanol and Water–NaCl Binary Mixtures

Energies ◽  
2020 ◽  
Vol 13 (18) ◽  
pp. 4861
Author(s):  
Fabio Fanari ◽  
Giacomo Muntoni ◽  
Chiara Dachena ◽  
Renzo Carta ◽  
Francesco Desogus
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Reaction Time ◽  
Microwave Heating ◽  
Scientific Literature ◽  
Conventional Heating ◽  
Impedance Measurements ◽  
Positive Effects ◽  
Wide Range

Microwave heating offers a lot of advantages compared to conventional heating methods in the chemical reactions field due to its positive effects on reaction time and selectivity. Dielectric properties, and in particular permittivity, of substances and mixtures, are important for the optimization of microwave heating processes; notwithstanding this, specific databases are poor and far from being complete, and in the scientific literature very little data regarding these properties can be found. In this work, impedance measurements were carried out using a specially designed system to get the real and imaginary parts of the dielectric constant. The apparatus was tested in the estimation of permittivity of water–ethanol and water–NaCl mixtures, varying their composition to obtain a wide range of permittivity values. The results were compared to literature data and fitted with available literature models to verify the correspondence between them, finding that permittivity dependence on mixture composition can be effectively described by the models.

Use of the Inverse Temperature Profile in Microwave Processing of Advanced Ceramics

1992 ◽  
Vol 269 ◽  
Author(s):  
J.G.P. Binner ◽  
I.A. Al-Dawery ◽  
C. Aneziris ◽  
T.E. Cross
Keyword(s):  
Silicon Nitride ◽  
Temperature Profile ◽  
Microwave Heating ◽  
Microwave Sintering ◽  
Microwave Processing ◽  
Inverse Temperature ◽  
Advanced Ceramics ◽  
Reaction Bonding ◽  
Microwave Reaction

ABSTRACTAttempts are being made to exploit the inverse temperature profile which can be developed with microwave heating with respect to the processing of certain advanced ceramics. This paper discusses the results obtained to date during the microwave sintering of YBCO high-Tc superconductors and the microwave reaction bonding of silicon nitride.

Research on the Pavement Performance of Recycled Asphalt Mixture Processed by Microwave

2010 ◽  
Vol 148-149 ◽  
pp. 987-993
Author(s):  
Song Qing Zhu ◽  
Jin Fei Shi ◽  
Fei Hao
Keyword(s):  
Mechanical Properties ◽  
Low Temperature ◽  
Microwave Heating ◽  
Fatigue Cracks ◽  
Asphalt Mixture ◽  
Microwave Processing ◽  
Bending Test ◽  
Conventional Heating ◽  
Pavement Performance ◽  
Recycled Asphalt

In order to evaluate the pavement performance of recycled asphalt mixture processed by microwave, an experimental method was designed to compare the microwave heating with the conventional heating in recycling affection of asphalt mixture. The samples AC-13 were produced. Conventional and microwave heating performance of modified asphalt recycling test including the rutting test, the trabecular cold bending test, the Marshall immersion test, the freeze-thaw split test, and the splitting strength mechanical properties were test. The experimental results show that it is roughly the same in the high temperature stability and mechanical properties of these two areas, and at low temperature cracking resistance the use of microwave processing can improve the low temperature flexibility to reduce the surface temperature seasonal prone temperature shrinkage cracks and fatigue cracks. The stability on the water by using microwave processing can enhance the asphalt and aggregate adhesion so that mixture enhanced resistance to water damage, there is a better role in improving the water stability. These results could promote microwave recycling and provide the basis for the promotion applications.

scholarly journals Microwaves and Heterogeneous Catalysis: A Review on Selected Catalytic Processes

Catalysts ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 246 ◽  
Author(s):  
Vincenzo Palma ◽  
Daniela Barba ◽  
Marta Cortese ◽  
Marco Martino ◽  
Simona Renda ◽  
...  
Keyword(s):  
Heterogeneous Catalysis ◽  
Energy Saving ◽  
Microwave Heating ◽  
Microwave Radiation ◽  
Heterogeneous Catalysts ◽  
Conventional Heating ◽  
Specific Effects ◽  
Natural Choice ◽  
Future Challenges ◽  
Catalyzed Reactions

Since the late 1980s, the scientific community has been attracted to microwave energy as an alternative method of heating, due to the advantages that this technology offers over conventional heating technologies. In fact, differently from these, the microwave heating mechanism is a volumetric process in which heat is generated within the material itself, and, consequently, it can be very rapid and selective. In this way, the microwave-susceptible material can absorb the energy embodied in the microwaves. Application of the microwave heating technique to a chemical process can lead to both a reduction in processing time as well as an increase in the production rate, which is obtained by enhancing the chemical reactions and results in energy saving. The synthesis and sintering of materials by means of microwave radiation has been used for more than 20 years, while, future challenges will be, among others, the development of processes that achieve lower greenhouse gas (e.g., CO2) emissions and discover novel energy-saving catalyzed reactions. A natural choice in such efforts would be the combination of catalysis and microwave radiation. The main aim of this review is to give an overview of microwave applications in the heterogeneous catalysis, including the preparation of catalysts, as well as explore some selected microwave assisted catalytic reactions. The review is divided into three principal topics: (i) introduction to microwave chemistry and microwave materials processing; (ii) description of the loss mechanisms and microwave-specific effects in heterogeneous catalysis; and (iii) applications of microwaves in some selected chemical processes, including the preparation of heterogeneous catalysts.

scholarly journals A comparative study on quality parameters of pumpkin, melon and sunflower oils during thermal treatment

OCL ◽  
2019 ◽  
Vol 26 ◽  
pp. 32 ◽  
Author(s):  
Zhana Petkova ◽  
Ginka Antova
Keyword(s):  
Fatty Acid Composition ◽  
Fatty Acid ◽  
Thermal Treatment ◽  
Microwave Heating ◽  
Acid Composition ◽  
Seed Oil ◽  
Conventional Heating ◽  
Melon Seed ◽  
Sunflower Oils ◽  
Melon Seed Oil

Current paper reveals the impact of thermal treatment on the quality of two seed oils – pumpkin and melon compared to the quality of the most used oil – sunflower oil. Conventional and microwave heating were used for processing the oils. The duration of the thermal treatment was 9, 12 and 18 min for the conventional heating. The microwave heating was performed with two microwave powers of the equipment (600 W and 900 W) for 3, 6, 9 and 12 min. At every stage of the thermal processing were determined acid and peroxide value, the absorbance of the oils at 232 and 268 nm, tocopherol and fatty acid composition. It was observed that the degree of oxidation of the examined oils during microwave and conventional heating increased with the duration of the thermal process and the power of the microwaves. Also, the two methods of heating had a little impact on the processes leading to the formation of free fatty acids. Total tocopherols of the melon seed oil were more stable to thermal treatment. The amount of linoleic acid decreased in the pumpkin and sunflower oils during microwave treatment, while that of oleic and palmitic acid relatively increased. The biggest change in the fatty acid composition of both oils was found during microwave heating at 900W. The changes in fatty acid composition of thermally treated melon seed oil were insignificant. Overall, melon seed oil was observed to be more thermally stable than pumpkin and sunflower oils.

Characterization of microwave heating for hyperthermia cancer treatment

2021 ◽  
pp. 1-15
Author(s):  
A. R. Niknam ◽  
Sh. Dodge ◽  
M. Hajian ◽  
M. A. Ansari
Keyword(s):  
Cancer Treatment ◽  
Microwave Heating
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