Pulsed 35 Ghz Gyrotron with Overmoded Applicator for Sintering Experiments

1996 ◽  
Vol 430 ◽  
Author(s):  
A. W. Fliflet ◽  
R. P. Fischer ◽  
A. K. Kinkead ◽  
R. W. Bruce
Keyword(s):  
Microwave Sintering ◽  
Pulse Length ◽  
Microwave Furnace ◽  
Set Up ◽  
Nanocrystalline Alumina

AbstractThe microwave sintering of nanocrystalline alumina compacts is currently under investigation at NRL. This paper will discuss an overmoded microwave furnace based on a 35 GHz pulsed gyrotron which is currently being set up to extend ongoing microwave sintering experiments at 2.45 GHz to 35 GHz. The gyrotron operates at 70 kV and currents up to 10 A. It is driven by a hard tube, variable pulse length (1–15 μs) modulator at repetition rates up to 1 kHz. The gyrotron can produce peak powers up to 100 kW at an efficiency of 20%, and average powers up to 200 W. The gyrotron output is transported via pressurized Ka-Band waveguide to an overmoded resonator containing the workpiece. In initial experiments, the resonator will consist of a piece of WR-284 waveguide. The operation of the system in preliminary sintering experiments is described.

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.

Microwave Sintering of YSZ Electrolyte Materials for SOFC

2008 ◽  
Vol 368-372 ◽  
pp. 238-240 ◽  
Author(s):  
Xi Tang Wang ◽  
Girish M. Kale
Keyword(s):  
Microwave Sintering ◽  
X Ray Diffraction ◽  
Final Phase ◽  
X Ray ◽  
Microwave Furnace ◽  
Scanning Electron Microcopy ◽  
Conventional Sintering ◽  
Y2o3 Content ◽  
Ysz Electrolyte ◽  
Considerable Enhancement

Microwave sintering behaviors of four different compositions of YSZ electrolyte materials were investigated. The samples were sintered in 2.45GHz microwave furnace. For comparison, conventional sintering was performed at 1821K.The densities of sintered samples showed considerable enhancement in the densification process under the influence of microwave fields. The samples with lower Y2O3 content are easy to sinter. The influence of the composition and sintering methods on the final phase composition and microstructure were investigated by X-ray diffraction and scanning electron microcopy. Finer and more uniform microstructures were observed in the microwave sintered samples comparing to the conventionally sintered samples.

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.

Comparison Study in Consolidation of Yttria Reinforced Iron-Chromium Composites Using Conventional and Microwave Sintering Technique

2013 ◽  
Vol 594-595 ◽  
pp. 832-836
Author(s):  
M. Marina ◽  
M.Z.M. Zamzuri ◽  
Mohd Nazree Derman ◽  
Mohd Asri Selamat ◽  
Z. Nooraizedfiza
Keyword(s):  
Mechanical Properties ◽  
Powder Metallurgy ◽  
Microwave Sintering ◽  
Slow Heating ◽  
Comparison Study ◽  
Sintering Time ◽  
Microwave Furnace ◽  
Crucible Furnace ◽  
Iron Based ◽  
Iron Chromium

This research is focused on studying the density and mechanical properties of iron-chromium composites consolidated by innovative rapid microwave sintering technology against conventionally sintered counterparts using slow heating crucible furnace. Another aim of this study is to assess the viability of yttria (Y2O3) ceramic particulates as reinforcement to the iron-chromium composites. Fabrication of iron-chromium-yttria composites consolidated in microwave furnace and conventional crucible furnace was successfully accomplished. Improvement of density is evident in microwave sintered composites. The Y2O3 addition significantly increases the hardness of the composite (118 Hv for microwave specimens as opposed to 110Hv for conventional specimens). The study also successfully established the viability of microwave sintering technique for consolidating iron based powder metallurgy composites by up to 80% reduction of sintering time.

The Effect of Heating Rate and Temperature on Mechanical and Microstructure Properties of β-TCP by Microwave Sintering

2017 ◽  
Vol 264 ◽  
pp. 91-94
Author(s):  
Chuthathip Mangkonsu ◽  
Ahmad Fauzi Mohd Noor ◽  
Banhan Lila ◽  
Kawashita Masakazu
Keyword(s):  
Heating Rate ◽  
Microwave Sintering ◽  
Sintered Sample ◽  
Mechanical Analysis ◽  
Heating Rates ◽  
Microwave Furnace ◽  
Different Temperatures

This aim of this work was to evaluate the influences of the heating rates and sintering temperatures for sintering β-TCP by microwave furnace. In the first part of work, the heating rates used for sintering β-TCP were including 10, 20, 30 and 40°C/min. Results from physical and mechanical analysis shown that the optimum properties were shown by samples produced at heating rate of 30°C/min. In the second part of the study, the heating rate of 30°C/min was continuing used to sintering samples by different temperatures (1200°C, 1250°C and 1300°C). The sintered sample at 1200°C presented the optimum properties in the physical and mechanical analysis. Finally, the sintered samples by the heating rate 30°C/min at 1200°C were in immersed in SBF to confirm the bioactivity property of β-TCP.

Microwave Sintering of Pure Iron with Addition of Stearic Acid as Binder

2012 ◽  
Vol 576 ◽  
pp. 166-169
Author(s):  
W. Rahman ◽  
Shamsul Baharin Jamaludin ◽  
Mohd Noor Mazlee
Keyword(s):  
Stearic Acid ◽  
Pure Iron ◽  
Sintering Temperature ◽  
Microwave Sintering ◽  
Micro Hardness ◽  
Sintering Time ◽  
Microwave Furnace ◽  
Optimum Material ◽  
Lower Bulk Density ◽  
Sintered Product

The purpose of this study is to investigate the effect of the stearic acid as binder in sintering pure iron using a microwave furnace. The study was focused in mechanical properties such as porosity, density and micro-hardness of sintered product. The experiment was done by varying weight percentages of stearic acid and controlling the sintering parameters such as sintering temperature and sintering time. Increasing the percentage of stearic acid resulted in higher porosity and lower bulk density. Hardness has increased by increasing sintering temperature and sintering time. The optimum material properties were found at 1300 °C sintering temperature with addition 2 % stearic acid within 30 minutes sintering time.

scholarly journals Alumina ceramics obtained by chemical synthesis using conventional and microwave sintering

Cerâmica ◽  
2011 ◽  
Vol 57 (341) ◽  
pp. 45-49 ◽  
Author(s):  
D. Thomazini ◽  
M. V. Gelfuso ◽  
A. S. A. Chinelatto ◽  
A. L. Chinelatto ◽  
F. K. Sanson ◽  
...  
Keyword(s):  
Pechini Method ◽  
Microwave Sintering ◽  
Potential Candidate ◽  
Alumina Ceramics ◽  
Pure Alumina ◽  
Nanosized Powders ◽  
Fine Grained ◽  
Conventional Furnace ◽  
Microwave Furnace ◽  
Conventional Sintering

It is well known that the heating mechanism and powder precursor define the microstructural characteristics of ceramics. Especially abnormal grain growth of pure alumina ceramics developed during conventional sintering method suggests that this material is a potential candidate to be treated in microwave sintering process. Alumina ceramics produced with commercial (A1K) and chemically synthesized powders were sintered in conventional and microwave furnaces. Two methods were employed to prepare the chemically synthesized nanosized powders: Pechini method and emulsification with oleic acid. The microwave sintered samples were characterized by apparent density and scanning electron microscopy and compared with the samples sintered in a conventional furnace. Alumina ceramics sintered in the microwave furnace had fine grained microstructure, not related with the starting powders. This characteristic was achieved in a sintering time shorter than those produced in the conventional furnace. However, satisfactory densification was observed only to A1K ceramics (3.95 g/cm³) sintered during one hour in microwave furnace.

Study of TiC Cutting Tool Insert Using Microwave Synthesis

2011 ◽  
Vol 52-54 ◽  
pp. 2116-2121 ◽  
Author(s):  
Shahdura Hammad Thauri ◽  
Tasnim Firdaus Ariff ◽  
A.N. Mustafizul Karim
Keyword(s):  
Cutting Tool ◽  
Microwave Sintering ◽  
Hot Isostatic Pressing ◽  
Material Synthesis ◽  
The Past ◽  
Microwave Furnace ◽  
Conventional Sintering ◽  
The Difference ◽  
Cutting Tool Insert ◽  
Hardness Values

Microwave processing ceramics is emerging fast as a new field of ceramic processing and material synthesis. The past year has witnessed significant progress in the aspects of commercialization and application of the technology to new areas. Further research states that Titanium Carbide (TiC) is the best cutting tool due to its high melting point and by that reason this project aims to show the difference between conventional sintering, microwave sintering and Hot Isostatic Pressing (HIP). Two different compositions consisting of 97TiC3Ni and 93TiC7Ni were sintered using conventional furnace, microwave furnace and HIP. Density, hardness and microstructure analysis were carried out on these TiC inserts. 97TiC3Ni produced higher density and hardness values compared to 93TiC7Ni for all three different methods. Microwave sintering produced the highest density and hardness values compared to conventional sintering and HIP. Microwave produced samples with improved density and hardness in a shorter processing time which is 93% faster than conventional sintering and 50% faster than HIP.

Structural, Electrical and Magnetic Properties of Microwave Processed Ni0.80Zn0.20Fe2O4

2013 ◽  
Vol 547 ◽  
pp. 25-30
Author(s):  
Renu Rani ◽  
Sangeeta Singh ◽  
K.K. Raina ◽  
Chandra Prakash
Keyword(s):  
Magnetic Properties ◽  
Single Phase ◽  
Microwave Sintering ◽  
Sem Analysis ◽  
X Ray Diffraction ◽  
Solid State Method ◽  
Cross Sectional ◽  
Electrical And Magnetic Properties ◽  
Microwave Furnace ◽  
Material Sample

The material sample was prepared by conventional solid state method and sintered in conventional and microwave furnace at different sintering temperatures. Sintered samples were then subjected to XRD and SEM analysis. X-ray diffraction revealed the formation of single phase material. SEM of fractured cross sectional portion showed that finer grains were formed in case of microwave sintering. The dielectric properties and magnetic properties were recorded for both the samples and both properties were found to improve in microwave sintered samples. There is also a significant improvement in density and magnetic properties by microwave processing.

scholarly journals Microwave Sintering of SiAlON Ceramics with TiN Addition

Materials ◽  
2019 ◽  
Vol 12 (8) ◽  
pp. 1345 ◽  
Author(s):  
Özgür Sevgi Canarslan ◽  
Roberto Rosa ◽  
Levent Köroğlu ◽  
Erhan Ayas ◽  
Alpagut Kara ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Vickers Hardness ◽  
Microwave Sintering ◽  
Single Mode ◽  
Nominal Composition ◽  
Indentation Fracture ◽  
Microwave Furnace ◽  
Indentation Fracture Toughness ◽  
Difference Time

α-β SiAlON/TiN composites with nominal composition of α:β = 25:75 were fabricated by microwave sintering. The effect of titanium nitride addition on the phases, microstructure, microwave absorption ability and mechanical properties (Vickers hardness and fracture toughness) of the SiAlON-based composites were studied. Finite Difference Time Domain (FDTD) software was used for the numerical simulation in order to assess the most suitable experimental setup. Sintering trials were performed in a single mode microwave furnace operating at 2.45 GHz and a power output of 660 W, for a reaction time of 30 min. SiC blocks were used as a susceptor to accelerate the microwave processing by hybrid heating, with reduced heat losses from the surface of the material of the α-β SiAlON/TiN composites. The optimum comprehensive mechanical properties, corresponding to a relative density of 96%, Vickers hardness of 12.98 ± 1.81 GPa and Vickers indentation fracture toughness of 5.52 ± 0.71 MPa.m1/2 were obtained at 850 °C when the content of TiN was 5 wt.%.

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