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.

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.

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.

Effects of Substitution SiC for SiO2 on Microwave Heating of ZrO2-Al2O3-SiO2 System Composites

2008 ◽  
Vol 368-372 ◽  
pp. 768-770
Author(s):  
Wei Fan ◽  
Jia Chen Liu ◽  
Xin He ◽  
Wei Wan ◽  
Chang Liu
Keyword(s):  
Microwave Heating ◽  
Microwave Power ◽  
Microwave Sintering ◽  
Effective Means ◽  
Holding Time ◽  
Temperature Phase ◽  
Sio2 System ◽  
Foundational Research

As a foundational research for microwave sintering or joining of ceramics related to ternary ZrO2-Al2O3-SiO2 system, effects of substitution SiC for SiO2 on rates of raising temperature, phase evolutions and microstructures were investigated. Influences of microwave power and holding time on heating were examined in means of detecting formation of mullite. It was proved to be an effective means to substitute SiC for SiO2 in microwave heating of ternary ZrO2-Al2O3-SiO2 system.

Sinthesys of Mullite Using Microwave Furnace from Kaolin and Alumina Residue

2014 ◽  
Vol 798-799 ◽  
pp. 63-68
Author(s):  
Michelle Félix da Silva ◽  
Valmir José da Silva ◽  
Romualdo Rodrigues Menezes ◽  
Lisiane Navarro de Lima Santana ◽  
Gelmires Araújo Neves ◽  
...  
Keyword(s):  
Temperature Gradient ◽  
Microwave Heating ◽  
Conventional Method ◽  
Microwave Power ◽  
Electromagnetic Energy ◽  
The Other ◽  
Heat Flows ◽  
Other Hand ◽  
Microwave Furnace

Heating with microwave power is a process in which the materials take up electromagnetic energy volumetrically and turn it into heat inside a piece. This is the great difference from the conventional method, where the heat flows between objects by means of conduction, radiation and convection, in which the surface of the materials is heated first, and then the heat is transferred to the interior of the piece, thus forming a temperature gradient. On the other hand, microwave heating generates heat first inside the piece, heating the whole volume later. [1]

Influence of Specific Absorbed Microwave Power on Activation Energy of Densification in Ceramic Materials

1996 ◽  
Vol 430 ◽  
Author(s):  
Y. Bykov ◽  
A. Eremeev ◽  
V. Holoptsev
Keyword(s):  
Activation Energy ◽  
Silicon Nitride ◽  
Energy Balance ◽  
Experimental Method ◽  
Microwave Power ◽  
Ceramic Materials ◽  
Energy Of Activation ◽  
Initial Stage ◽  
Microwave Furnace ◽  
Apparent Energy Of Activation

AbstractCorrelation between the rate of densification in powder ceramic materials and specific absorbed microwave power is determined by the experimental method. The approach is based on a comparison of the densification curves obtained at different rates of heating. The changes in the ramping rate are provided by varying the microwave power fed into the microwave furnace. Using the energy balance for the microwave heated samples, the correlation between the apparent energy of activation at the initial stage of densification and the value of the specific microwave power absorbed in heated materials are found. The experiments with silicon nitride-based ceramics allowed to determine the reduction in the value of the activation energy resulted from an increase in the specific absorbed microwave power.

scholarly journals Scale-Up of the Nitridation and Sintering of Silicon Preforms Using Microwave Heating

1996 ◽  
Vol 430 ◽  
Author(s):  
J. O. Kiggans ◽  
T. N. Tiegs ◽  
C. C. Davisson ◽  
M. S. Morrow ◽  
G. J. Garvey
Keyword(s):  
Silicon Nitride ◽  
Microwave Heating ◽  
Diesel Engines ◽  
Scale Up ◽  
Microwave Furnace ◽  
Weight Gains

AbstractScale-up studies were performed in which microwave heating was used to fabricate reactionbonded silicon nitride and sintered reaction-bonded silicon nitride (SRBSN). Tests were performed in both a 2.45 GHz, 500 liter and a 2.45 GHz, 4000 liter multimode cavities. A variety of sizes, shapes, and compositions of silicon preforms were processed in the studies, including bucket tappets and clevis pins for diesel engines. Up to 230 samples were processed in a single microwave furnace run. Data were collected which included weight gains for nitridation experiments, and final densities for nitridation and sintering experiments. For comparison, nitridation and sintering studies were performed using a conventional resistance-heated furnace.

Grain boundary glassy phase and abnormal grain growth of silicon nitride ceramics

2001 ◽  
Vol 27 (5) ◽  
pp. 603-605 ◽  
Author(s):  
Haitao Yang ◽  
Lin Gao ◽  
Gangqin Shao ◽  
Runze Xu ◽  
Peiyun Huang
Keyword(s):  
Silicon Nitride ◽  
Grain Boundary ◽  
Grain Growth ◽  
Glassy Phase ◽  
Abnormal Grain Growth ◽  
Nitride Ceramics

Microwave Sintering of Zirconia Toughened Mullite (ZTM)

1994 ◽  
Vol 347 ◽  
Author(s):  
J. Cai ◽  
C. Y. Song ◽  
B. S. Li ◽  
X. X. Huang ◽  
J. K. Guo ◽  
...  
Keyword(s):  
Grain Size ◽  
Grain Growth ◽  
Microwave Sintering ◽  
Single Mode ◽  
Microwave Processing ◽  
Toughening Mechanism ◽  
Conventional Sintering

ABSTRACTMicrowave sintering of zirconia toughened mullite (ZTM) has been performed in a single mode applicator. In comparison with conventional sintering, microwave processing of ZTM leads to a higher density and finer grain size. Microstructure of microwave sintered ZTM was characterized by TEM and HRTEM techniques. The pinning of intergranular ZrO2 dispersoids retarded the grain growth of mullite matrix. The observation of a considerable number of trans-granular microcracks indicates that microcracking toughening is the main toughening mechanism for ZTM.

Microwave sintering of ZnO at ultra high heating rates

2001 ◽  
Vol 16 (10) ◽  
pp. 2850-2858 ◽  
Author(s):  
Geng-fu Xu ◽  
Isabel K. Lloyd ◽  
Yuval Carmel ◽  
Tayo Olorunyolemi ◽  
Otto C. Wilson
Keyword(s):  
Grain Size ◽  
Heating Rate ◽  
Microwave Heating ◽  
Grain Growth ◽  
Rapid Heating ◽  
Microwave Sintering ◽  
Complete Suppression ◽  
Heating Rates ◽  
High Heating ◽  
Size Uniformity

In this paper, a unique processing approach for producing a tailored, externally controlled microstructure in zinc oxide using very high heating rates (to 4900 °C/min) in a microwave environment is discussed. Detailed data on the densification, grain growth, and grain size uniformity as a function of heating rate are presented. With increasing heating rate, the grain size decreased while grain size uniformity increased. At extremely high heating rates, high density can be achieved with almost complete suppression of grain growth. Ultrarapid microwave heating of ZnO also enhanced densification rates by up to 4 orders of magnitude compared to slow microwave heating. The results indicate that the densification mechanisms are different for slow and rapid heating rates. Since the mechanical, thermal, dielectric, and optical properties of ceramics depend on microstructure, ultrarapid heating may lead to advanced ceramics with tailored microstructure and enhanced properties.

Microwave Sintering of Pure and Doped Nanocrystalline Alumina Compacts

1996 ◽  
Vol 430 ◽  
Author(s):  
R. W. Bruce ◽  
A. W. Fliflet ◽  
L. K. Kurihara ◽  
G.-M. Chow ◽  
P. E. Schoen
Keyword(s):  
Grain Growth ◽  
Room Temperature ◽  
Microwave Sintering ◽  
Sol Gel ◽  
Single Mode ◽  
Nanocrystalline Powders ◽  
Sintering Process ◽  
Effect Of Additives ◽  
Microwave Furnace ◽  
Nanocrystalline Alumina

AbstractA single-mode cavity microwave furnace, operating in the TE103 mode at 2.45 GHz is being used to investigate sintering of pure and doped nanocrystalline alumina. The purpose of these experiments is to determine the effect of additives on the sintering process in the nanocrystalline regime. Using the sol-gel method, high purity Al2O3 nanocrystalline powders were synthesized. These powders were calcined at 700°C and then CIP'ed to 414 MPa, producing 0.4 in. diameter, 0.25 in. high cylindrical compacts. The compacts were heated in the microwave furnace to temperatures between 1100°C to approximately 1800°C and were then brought back to room temperature using a triangular heating profile of about 30 minutes duration. A two-color IR pyrometer was used to monitor the surface temperature of the workpiece. The additives tested in this work lowered the temperature needed for densification but this effect was offset by increased grain growth. Initial grain growth from < 5 nm to ∼ 50 nm was closely correlated with the γ to α-alumina phase transition.

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