scholarly journals Fabrication of Mems Devices by Powder-Filling into DXRL-Formed Molds

1998 ◽  
Vol 546 ◽  
Author(s):  
Terry J. Garino ◽  
Todd Christenson ◽  
Eugene Venturini
Keyword(s):  
High Temperature ◽  
Bulk Material ◽  
The Other ◽  
Ceramic Mold ◽  
Magnetic Powder ◽  
Mems Devices ◽  
X Ray ◽  
Energy Product ◽  
Zn Ferrite ◽  
Micro Actuators

AbstractWe have developed a variety of processes for fabricating components for micro devices based on deep x-ray lithography (DXRL). Although the techniques are applicable to many materials, we have demonstrated them using hard (Nd 2Fe14B) and soft (Ni-Zn ferrite) magnetic materials because of the importance of these materials in magnetic micro-actuators and other devices and because of the difficulty fabricating them by other means. The simplest technique involves pressing a mixture of magnetic powder and a binder into a DXRL-formed mold. In the second technique, powder is pressed into the mold and then sintered to densify. The other two processes involve pressing at high temperature either powder or a dense bulk material into a ceramic mold that was previously made using a DXRL mold. These techniques allow arbitrary 2-dimensional shapes to be made 10 to 1000 μm thick with in-plane dimensions as small as 50μm and dimensional tolerances in the micron range. Bonded isotropic Nd2Fe14B micro-magnets made by these processes had an energy product of 7 MGOe.

In-Situ High Temperature XRD on U0.54Pu0.46O2-x A Study of the Miscibility Gap

2015 ◽  
Vol 1743 ◽  
Author(s):  
Michal Strach ◽  
Renaud C. Belin ◽  
Jean-Christophe Richaud ◽  
Jacques Rogez
Keyword(s):  
High Temperature ◽  
Rietveld Refinement ◽  
Calphad Method ◽  
The Other ◽  
Miscibility Gap ◽  
X Ray ◽  
Cubic Phases ◽  
High Temperature Xrd ◽  
Metal Ratio

ABSTRACTIt has been shown in previous studies that a miscibility gap exists in the hypo-stoichiometric region UO2-PuO2-Pu2O3 with one phase poor in oxygen, and the other with an O/M (Oxygen to Metal ratio) close to 2.00. Data on the evolution of this region in temperature, especially in the vicinity of the oxygen content corresponding to the highest temperature at which the gap can be observed, is scarce. A high temperature X-ray diffractometer with a dedicated gas control setup was used to study the described region in-situ. We have observed reflections of the two cubic phases, with one increasing and the other decreasing in intensity during the thermal plateaus lasting up to 20 h. We compare the calculated lattice parameters with literature. We estimated the O/M evolution of our samples from a comparison of phase fractions values obtained by Rietveld refinement and calculations using the Calphad method.

High-Temperature Transport Properties of Indium Added Cobalt-Antimonide Based Skutterudites Processed by Current Assisted Short-Term Sintering

2010 ◽  
Vol 74 ◽  
pp. 54-59 ◽  
Author(s):  
Andreas Sesselmann ◽  
Ralf Hassdorf ◽  
Sebastian Zastrow ◽  
Eckhard Müller
Keyword(s):  
High Temperature ◽  
Bulk Material ◽  
Process Time ◽  
Material System ◽  
Short Term ◽  
X Ray ◽  
Functional Homogeneity ◽  
Cobalt Antimonide ◽  
Te Material ◽  
A Current

For more than a decade, skutterudites such as cobalt antimonides have been widely studied as a promising thermoelectric (TE) material for high-temperature applications. High thermoelectric figure of merit (ZT) in this material system can be achieved by suitable doping or by filling the interstitial voids with guest atoms. One of the best improvements in ZT is reported when indium (In) is used as additive to cobalt-antimonide skutterudites, as has been done in this study. Compaction of the grinded powders was carried out by a current-assisted short-term sintering device, which significantly reduces the process time in comparison to conventional hot pressing. Phase homogeneity of the bulk material has been probed by X-ray powder diffraction (XRD) and energy-dispersive X-ray spectroscopy (EDX). TE properties (i.e. electrical conductivity, Seebeck coefficient and thermal conductivity) have been analyzed in the temperature range from 300 K to 700 K. The functional homogeneity of the samples was screened by the Potential & Seebeck Microprobe (PSM). Adapted from these results the effect of indium addition to short-term sintered cobalt-antimonide based skutterudites with absence of impurity phases will be discussed.

scholarly journals In-Situ Isothermal Crystallization of Poly(l-lactide)

Polymers ◽  
2021 ◽  
Vol 13 (19) ◽  
pp. 3377
Author(s):  
Zirui Huang ◽  
Meiling Zhong ◽  
Haibo Yang ◽  
Enqin Xu ◽  
Dehui Ji ◽  
...  
Keyword(s):  
High Temperature ◽  
Nucleation Rate ◽  
Low Temperatures ◽  
Isothermal Crystallization ◽  
The Other ◽  
Wide Angle ◽  
X Ray Diffraction ◽  
X Ray ◽  
Different Temperatures

The isothermal crystallization of poly(l-lactide) (PLLA) has been investigated by in-situ wide angle X-ray diffraction (WAXD) and polarized optical microscopes (POM) equipped with a hot-stage accessory. Results showed that the spherulites of PLLA were formed at high temperature, whereas irregular morphology was observed under a low temperature. This can be attributed to the varying rates of crystallization of PLLA at different temperatures. At low temperatures, the nucleation rate is fast and hence the chains diffuse very slow, resulting in the formation of imperfect crystals. On the other hand, at high temperatures, the nucleation rate is slow and the chains diffuse fast, leading to the formation of perfect crystals. The change in the value of the Avrami exponent with temperature further verifies the varying trend in the morphological feature of the crystals.

scholarly journals Behavior of Two Foundry Cobalt-Based Alloys Exposed to a Hot Complex Gaseous Mixture Simulating the Atmosphere in a Waste-to-Energy Boiler. Part 1: Case of the Alloy Exposed to the Complex Gas Stream

2018 ◽  
Vol 5 ◽  
pp. 1-5
Author(s):  
Lionel Aranda ◽  
Thierry Schweitzer ◽  
Patrice Berthod ◽  
Christophe Rapin ◽  
Didier Souchon ◽  
...  
Keyword(s):  
Water Vapor ◽  
High Temperature ◽  
Working Conditions ◽  
Gaseous Mixture ◽  
The Other ◽  
Waste To Energy ◽  
Gas Mixture ◽  
Refractory Materials ◽  
X Ray Diffraction ◽  
X Ray

The refractory materials required for waste-to-energy boilers endure severe working conditions, such as exposure to heat and hot oxidation / corrosion. Thanks to their high temperature properties cobalt-based alloys may respond to these properties requirements. In this work two model alloys based on cobalt and rich in chromium were elaborated by casting and samples were prepared by cutting and polishing. These samples were exposed, one to a hot complex gaseous mixture particularly aggressive reproducing the atmosphere in WtE boilers in service (presence of water vapor, di-oxygen, carbon di-oxide, hydrogen chloride), and the other to synthetic ashes, both for more than two hundreds hours. After test the samples were characterized by X-ray diffraction and SEM observations. On sample exposed to the complex gas stream a {10 to 15μm}-thick oxide scale formed on the surface of the sample exposed to the gas mixture. It involved all the elements of the alloy and it obviously developed both inwards and outwards as suggested by the position of the oxidized carbides.

XRD Studies on Transformation of Dolomite under CO2 and N2 Atmosphere

2020 ◽  
Vol 1010 ◽  
pp. 355-360
Author(s):  
Siti Sarahah Sulhadi ◽  
Maratun Najiha Abu Tahari ◽  
Salma Samidin ◽  
Wan Nor Roslam Wan Isahak ◽  
Muhammad Rahimi Yusop ◽  
...  
Keyword(s):  
High Temperature ◽  
Crystallite Size ◽  
Fluidized Bed ◽  
Chemical Reactions ◽  
Fluidized Bed Reactor ◽  
The Other ◽  
X Ray Diffraction ◽  
X Ray ◽  
Xrd Studies ◽  
Significant Chemical

In this study, dolomite was heated under CO2 and N2 gases using fluidized bed reactor from 85 °C to 835 °C. Dolomite under N2 atmosphere did not show any significant changes on its crystallite size, suggesting there is no significant chemical reaction. On the other hand, dolomite under CO2 atmosphere shows no significant changes on its crystallite size until it reaches high temperature (> 800 °C) where MgO started to be observed in X- ray diffraction. This shows that few chemical reactions started to happen in this reaction condition.

Phase Transition and Thermal Expansion of Ba3RB3O9 (R = Sm–Yb, and Y)

2017 ◽  
Vol 36 (8) ◽  
pp. 763-769 ◽  
Author(s):  
Rayko Simura ◽  
Shohei Kawai ◽  
Kazumasa Sugiyama
Keyword(s):  
Phase Transition ◽  
Thermal Expansion ◽  
High Temperature ◽  
Thermal Expansion Coefficient ◽  
Room Temperature ◽  
The Other ◽  
X Ray Diffraction ◽  
X Ray ◽  
Melting Temperatures ◽  
Type Phase

AbstractHigh temperature powder X-ray diffraction measurements of Ba3RB3O9 (R=Sm–Yb, and Y) were carried out at temperatures ranging from room temperature to just below the corresponding melting temperatures (1,200–1,300 °C). No phase transition was found for the H-type phase (R$\overline 3 $) with R=Sm–Tb and the L-type phase (P63 cm) with R=Tm–Yb. On the other hand, phase transition from the L phase to the H phase was observed for R=Dy–Er, and Y at around 1,100–1,200 °C. The obtained axial thermal expansion coefficient (ATEC) of the a-axis was larger than that of the c-axis for the H phase, and the ATEC of the c-axis was larger than that of the a-axis for the L phase. The observed anisotropic nature of ATEC is attributed to the distribution of the BO3 anionic group with rigid boron–oxygen bonding in the structures of the H and L phases.

Post-Irradiation Annealing of Laser-Formed Silicide Layers

1980 ◽  
Vol 1 ◽  
Author(s):  
M. Wittmer ◽  
M. von Allmen
Keyword(s):  
High Temperature ◽  
The Other ◽  
Silicide Phase ◽  
Vacuum Furnace ◽  
High Temperature Annealing ◽  
X Ray ◽  
Post Irradiation ◽  
Reaction Couple ◽  
Annealing Effects ◽  
Compositional Changes

ABSTRACTWe have investigated the post-irradiation annealing effects of laser-formed Pt, Pd, Rh and Ni-silicides. It was found from Rutherford backscattering and x-ray analysis that compositional changes occur during subsequent high temperature annealing in a vacuum furnace. Generally, a single silicide phase tends to form at the expense of the other phases present following laser irradiation. The surviving phase is not necessarily identical to the end-phase found in a binary solid-state reaction couple of the same system.

The X-ray pattern of low-temperature cristobalite

1944 ◽  
Vol 27 (187) ◽  
pp. 54-55 ◽  
Author(s):  
A. H. Jay
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Open Hearth ◽  
Crystalline Material ◽  
The Other ◽  
Raw Material ◽  
X Ray ◽  
Temperature Heating ◽  
High Temperature Heating ◽  
Roof Brick

Cristobalite is found as the first product in the conversion of quartz following a high-temperature heating, and it constitutes a large percentage of the crystalline material in most manufactured silica bricks. It is present also in fireclay products, the amount being dependent upon the nature of the raw material and the conditions of firing. In the majority of these products the cristobalite is only poorly developed, i.e. the crystals are only perfect over distances of the order of about 1 × 10-6 cm. This value is derived from the diffuseness of the high-order reflections on the X-ray powder photograph. On the other hand, the crystals of cristobalite are well developed in the hot face of an open hearth silica roof-brick.

Self-Propagating High-Temperature Synthesis of Ni-Cu-Zn Ferrites with Alternative Fuel of Carbon Powder

2014 ◽  
Vol 981 ◽  
pp. 887-890
Author(s):  
Zhen Hua Wang ◽  
Jiu Xing Jiang ◽  
Chang Long Tan ◽  
Zhi Han Zhu ◽  
Fan Xu
Keyword(s):  
High Temperature ◽  
Raw Materials ◽  
Spinel Phase ◽  
Carbon Powder ◽  
Temperature Synthesis ◽  
X Ray ◽  
High Temperature Synthesis ◽  
Zn Ferrite ◽  
Mass Fractions ◽  
Microstructure Density

Ni-Cu-Zn ferrite powders were prepared by self-propagating high-temperature synthesis (SHS) using carbon powder with different mass fractions as fuel. The effects of carbon content in the raw materials on the phase composition, microstructure, density and magnetic property of the Ni-Cu-Zn powders were investigated by X-ray diffractometry(XRD), scanning electron microscope(SEM) and vibrating sample magnetometer(VSM), respectively. The results show that the use of carbon as a fuel brings no other impurities and improved the permeability. The single spinel phase powder was obtained when the precursor materials with a carbon powder of 5% in mass were used.

Tris(ethyldimethylphenylammonium) nonahalogenodibismuthates(III)

1999 ◽  
Vol 54 (3) ◽  
pp. 305-313 ◽  
Author(s):  
H. Eickmeier ◽  
Bernd Jaschinski ◽  
A. Hepp ◽  
Jürgen Nuß ◽  
Hans Reuter ◽  
...  
Keyword(s):  
Crystal Structure ◽  
High Temperature ◽  
Powder Diffraction ◽  
Lattice Parameters ◽  
The Other ◽  
Temperature Dependent ◽  
X Ray ◽  
Dsc Measurements ◽  
Structure Determinations ◽  
High Temperature Modification

The halogenobismuthates Q3Bi2X9 (Q = EtMe2PhN; X = Cl, Br, I) were prepared by reaction of BiX3 with EtMe2PhNX in ethanol. Single crystal structure determinations yielded: [EtMe2PhN]3[Bi2Cl9], S.G. P212121, Nr. 19, a = 952.5(3), b = 1184.1(4), c = 3726.4(9 pm, Z = 2;[EtMe2PhN]3[Bi2Br9] S.G .P21/c , No. 14, a= 1839.4(4),b= 1329.5(3), c = 1817.3(6)pm, β = 92.68(3)°, Z = 4, [EtMe2PhN]3[Bi2l9], ], S.G . P21/c, No. 14, a = 1915.3(2), b = 1379.0(3), c = 1890.9(5) pm, β = 92.48(1)°, Z = 4. The thermal behaviour was investigated with the aid of DSC measurements and temperature dependent X-ray powder diffraction. All compounds undergo a transition into a high temperature modification which could be obtained in case of [EtMe2PhN]3[Bi2Br9-xIx] in form of single crystals: S.G . P21/c, Nr. 14, a = 1002.7(5), b = 1278.7 (8), c = 3584.3(5) pm, β = 90.12(2)°, Z = 4. Surprisingly in this compound the iodine atoms are not statistically distributed over all possible bromine positions, but occupy only one position. Lattice parameters of the other high temperature modifications and enthalpies of transition of the compounds are given. In addition a second iodobismuthate was isolated:[EtMe2PhN]4[Bi6l22], S.G . P1̄, Nr. 2 , with lattice parameters of a = 1343.4(3), b = 1554.3(3), c = 2262.5(6) pm, a = 100.89(3)°, β = 96.63(1)°, 7 = 98.94(2)° and Z = 2.

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