Pressureless Co-Sintering of Al2O/ZrO2 Multilayers and Bilayers

1996 ◽  
Vol 434 ◽  
Author(s):  
Peter Z. Cai ◽  
David J. Green ◽  
Gary L. Messing
Keyword(s):  
Thermal Expansion ◽  
Cyclic Loading ◽  
Microscopic Observation ◽  
Surface Defects ◽  
Tape Casting ◽  
Thermal Expansion Mismatch ◽  
Heating Rates ◽  
The Difference ◽  
Extent Of Damage ◽  
Transverse Damage

AbstractVarious types of damage were observed in pressureless-sintered Al2O3/ZrO2 symmetric laminates (multilayers) and asymmetric laminates (bilayers) fabricated by tape casting and lamination. These defects included channel defects in ZrO2-containing layers, Al2O3 surface defects parallel to the layers, decohesion between the layers, and transverse damage within the Al2O3 layer in the bilayers. Detailed microscopic observation attributed the defects to a combined effect of mismatch in both sintering rate and thermal expansion coefficient between the layers. Crack-like defects were formed in the early stages of densification, and these defects acted as pre-existing flaws for thermal expansion mismatch cracks. Curling of the bilayers during sintering was monitored and the measured rate of curvature change, along with the layer viscosities obtained by cyclic loading dilatometry, was used to estimate the sintering mismatch stresses. The extent of damage could be reduced or even eliminated by decreasing the difference in layer sintering rate. This was accomplished by reducing the heating rates or by adding Al2O3 in the ZrO2 layers.

Microstructural and Microchemical Characterization of Nickel Sulfide Inclusions in Plate Glass

1991 ◽  
Vol 49 ◽  
pp. 962-963
Author(s):  
J. Cooper ◽  
O. Popoola ◽  
W. M. Kriven
Keyword(s):  
Thermal Expansion ◽  
Phase Transformation ◽  
Glass Matrix ◽  
Nickel Sulfide ◽  
Plate Glass ◽  
Thermal Expansion Mismatch ◽  
Volume Increase ◽  
Β Phase ◽  
Microchemical Characterization

Nickel sulfide inclusions have been implicated in the spontaneous fracture of large windows of tempered plate glass. Two alternative explanations for the fracture-initiating behaviour of these inclusions have been proposed: (1) the volume increase which accompanies the α to β phase transformation in stoichiometric NiS, and (2) the thermal expansion mismatch between the nickel sulfide phases and the glass matrix. The microstructure and microchemistry of the small inclusions (80 to 250 μm spheres), needed to determine the cause of fracture, have not been well characterized hitherto. The aim of this communication is to report a detailed TEM and EDS study of the inclusions.

scholarly journals Unravelling thermal stress due to thermal expansion mismatch in metal–organic frameworks for methane storage

2021 ◽  
Author(s):  
Jelle Wieme ◽  
Veronique Van Speybroeck
Keyword(s):  
Thermal Expansion ◽  
Thermal Stress ◽  
Pressure Coefficient ◽  
Metal Organic Frameworks ◽  
Methane Storage ◽  
Thermal Expansion Mismatch ◽  
Thermal Pressure ◽  
Temperature Changes ◽  
Metal Organic ◽  
The Impact

Thermal stress is present in metal–organic frameworks undergoing temperature changes during adsorption and desorption. We computed the thermal pressure coefficient as a proxy for this phenomenon and discuss the impact of thermal expansion mismatch.

Algorithms for Density, Potential Temperature, Conservative Temperature, and the Freezing Temperature of Seawater

2006 ◽  
Vol 23 (12) ◽  
pp. 1709-1728 ◽  
Author(s):  
David R. Jackett ◽  
Trevor J. McDougall ◽  
Rainer Feistel ◽  
Daniel G. Wright ◽  
Stephen M. Griffies
Keyword(s):  
Thermal Expansion ◽  
Equation Of State ◽  
Thermodynamic Potential ◽  
Potential Temperature ◽  
Inverse Function ◽  
Freezing Temperature ◽  
Ocean Models ◽  
The Difference ◽  
New Equation ◽  
Density Equation

Abstract Algorithms are presented for density, potential temperature, conservative temperature, and the freezing temperature of seawater. The algorithms for potential temperature and density (in terms of potential temperature) are updates to routines recently published by McDougall et al., while the algorithms involving conservative temperature and the freezing temperatures of seawater are new. The McDougall et al. algorithms were based on the thermodynamic potential of Feistel and Hagen; the algorithms in this study are all based on the “new extended Gibbs thermodynamic potential of seawater” of Feistel. The algorithm for the computation of density in terms of salinity, pressure, and conservative temperature produces errors in density and in the corresponding thermal expansion coefficient of the same order as errors for the density equation using potential temperature, both being twice as accurate as the International Equation of State when compared with Feistel’s new equation of state. An inverse function relating potential temperature to conservative temperature is also provided. The difference between practical salinity and absolute salinity is discussed, and it is shown that the present practice of essentially ignoring the difference between these two different salinities is unlikely to cause significant errors in ocean models.

Alucone Interlayers to Minimize Stress Caused by Thermal Expansion Mismatch between Al2O3 Films and Teflon Substrates

2013 ◽  
Vol 5 (3) ◽  
pp. 1165-1173 ◽  
Author(s):  
Shih-Hui Jen ◽  
Steven M. George ◽  
Robert S. McLean ◽  
Peter F. Carcia
Keyword(s):  
Thermal Expansion ◽  
Thermal Expansion Mismatch ◽  
Al2o3 Films

scholarly journals Nitrile versus isonitrile adsorption at interstellar grain surfaces

2017 ◽  
Vol 608 ◽  
pp. A50 ◽  
Author(s):  
M. Bertin ◽  
M. Doronin ◽  
X. Michaut ◽  
L. Philippe ◽  
A. Markovits ◽  
...  
Keyword(s):  
Density Functional ◽  
Surface Defects ◽  
High Vacuum ◽  
Solid Support ◽  
Ultra High Vacuum ◽  
Structural Defects ◽  
Adsorption Energies ◽  
The Difference ◽  
Temperature Programmed ◽  
Open Question

Context. Almost 20% of the ~200 different species detected in the interstellar and circumstellar media present a carbon atom linked to nitrogen by a triple bond. Of these 37 molecules, 30 are nitrile R-CN compounds, the remaining 7 belonging to the isonitrile R-NC family. How these species behave in their interactions with the grain surfaces is still an open question. Aims. In a previous work, we have investigated whether the difference between nitrile and isonitrile functional groups may induce differences in the adsorption energies of the related isomers at the surfaces of interstellar grains of various nature and morphologies. This study is a follow up of this work, where we focus on the adsorption on carbonaceous aromatic surfaces. Methods. The question is addressed by means of a concerted experimental and theoretical approach of the adsorption energies of CH3CN and CH3NC on the surface of graphite (with and without surface defects). The experimental determination of the molecule and surface interaction energies is carried out using temperature-programmed desorption in an ultra-high vacuum between 70 and 160 K. Theoretically, the question is addressed using first-principle periodic density functional theory to represent the organised solid support. Results. The adsorption energy of each compound is found to be very sensitive to the structural defects of the aromatic carbonaceous surface: these defects, expected to be present in a large numbers and great diversity on a realistic surface, significantly increase the average adsorption energies to more than 50% as compared to adsorption on perfect graphene planes. The most stable isomer (CH3CN) interacts more efficiently with the carbonaceous solid support than the higher energy isomer (CH3NC), however.

Shape forming by thermal expansion mismatch and shape memory locking in polymer/elastomer laminates

2017 ◽  
Vol 26 (10) ◽  
pp. 105027 ◽  
Author(s):  
Chao Yuan ◽  
Zhen Ding ◽  
T J Wang ◽  
Martin L Dunn ◽  
H Jerry Qi
Keyword(s):  
Thermal Expansion ◽  
Shape Memory ◽  
Thermal Expansion Mismatch

Rapid shear alignment of sub-10 nm cylinder-forming block copolymer films based on thermal expansion mismatch

Nano Futures ◽  
2018 ◽  
Vol 1 (3) ◽  
pp. 035006
Author(s):  
Samuel M Nicaise ◽  
Karim R Gadelrab ◽  
Amir Tavakkoli K G ◽  
Caroline A Ross ◽  
Alfredo Alexander-Katz ◽  
...  
Keyword(s):  
Thermal Expansion ◽  
Block Copolymer ◽  
Thermal Expansion Mismatch ◽  
Shear Alignment ◽  
Copolymer Films

scholarly journals Large Thermal Expansion LTCC System for Cofiring with Integrated Functional Ceramics Layers

Materials ◽  
2022 ◽  
Vol 15 (2) ◽  
pp. 564
Author(s):  
Beate Capraro ◽  
Manuel Heidenreich ◽  
Jörg Töpfer
Keyword(s):  
Thermal Expansion ◽  
Ceramic Composite ◽  
Sintering Behavior ◽  
Heating Rates ◽  
Partial Crystallization ◽  
Tan Δ ◽  
Low K ◽  
Glass Ceramic Composite ◽  
Functional Ceramics ◽  
Functional Ceramic

We have studied the sintering behavior of CT708 LTCC tapes with large CTE of 10.6 ppm/K. This low-k dielectric LTCC material is a quartz-based glass ceramic composite system with partial crystallization of celsian upon firing. The shrinkage, densification and dielectric properties were examined using different heating rates and a sintering temperature of 900 °C. The maximum shrinkage rate is at 836 °C (for a heating rate of 2 K/min) with a sintering density of 95% and a permittivity of ε’ = 5.9 and tan δ = 0.0004 (at 1 GHz). Due to their similar shrinkage and thermal expansion properties, CT708 tapes may be cofired with functional ceramic layers. As an example, we report on cofiring of a multilayer laminate of CT708 and a Sc-substituted hexagonal ferrite for applications as integrated microwave circulator components. This demonstrates the feasibility of cofiring of functional ceramic tapes and tailored LTCC tapes and documents the potential for the realization of complex LTCC multilayer architectures.

scholarly journals Opening Material as the Possibility of Elimination Veining in Foundries

2016 ◽  
Vol 16 (3) ◽  
pp. 157-161 ◽  
Author(s):  
M. Hrubovčáková ◽  
I. Vasková ◽  
M. Benková ◽  
M. Conev
Keyword(s):  
Thermal Conductivity ◽  
Particle Size ◽  
Thermal Expansion ◽  
Cast Iron ◽  
Granular Material ◽  
Surface Defects ◽  
Silica Sand ◽  
Iron Castings ◽  
Thermal Dilatation

Abstract The main bulk density representation in the molding material is opening material, refractory granular material with a particle size of 0.02 mm. It forms a shell molds and cores, and therefore in addition to activating the surface of the grain is one of the most important features angularity and particle size of grains. These last two features specify the porosity and therefore the permeability of the mixture, and thermal dilatation of tension from braking dilation, the thermal conductivity of the mixture and even largely affect the strength of molds and cores, and thus the surface quality of castings. [1] Today foundries, which use the cast iron for produce of casts, are struggling with surface defects on the casts. One of these defects are veining. They can be eliminated in several ways. Veining are foundry defects, which arise as a result of tensions generated at the interface of the mold and metal. This tension also arises due to abrupt thermal expansion of silica sand and is therefore in the development of veining on the surface of casts deal primarily influences and characteristics of the filler material – opening material in the production of iron castings.

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