Characterization of the CaCO3 calcination process by the Porod invariant behaviour

2021 ◽  
Vol 54 (4) ◽  
Author(s):  
Salvino Ciccariello
Keyword(s):  
Amorphous Phase ◽  
Volume Fraction ◽  
Variable Density ◽  
Constant Density ◽  
Surface Areas ◽  
Third Phase ◽  
Powder Samples ◽  
Best Fitting ◽  
Two Phases

The concave behaviour of the Porod invariant observed during the calcination of CaCO3 powder samples suggests the following picture of the evolving internal structure of the samples. The outset sample is formed by a crystalline CaCO3 phase and a void phase. During the calcination, the first phase shrinks in volume at fixed density since the temperature increase breaks down the crystalline structure at the interface, leading to the formation of an amorphous phase comprising an equal number of CO2 and CaO atomic groups. The last groups gradually condense, forming a third phase of solid CaO of constant density and increasing volume fraction, while the companion CO2 groups flow out of the sample. The amorphous phase occupies, with a variable density, all the volume left free by the other two phases. At the end of the calcination, both the volume fraction of the first phase and the density of the amorphous phase vanish so that the sample will again be made up of two phases: the voids and the solid CaO. Best-fitting the resulting theoretical expressions of the Porod invariant and of the Porod law coefficient to the observed values, one can determine the matter densities, volume fractions and specific surface areas of the phases.

Precipitation of NiHfsi phase in NiAl single crystals containing Hf

1995 ◽  
Vol 53 ◽  
pp. 532-533
Author(s):  
A. Garg ◽  
R. D. Noebe ◽  
R. Darolia
Keyword(s):  
High Temperature ◽  
Single Crystals ◽  
High Temperature Strength ◽  
Bridgman Technique ◽  
Shell Mold ◽  
Third Phase ◽  
Unknown Phase ◽  
Transmission Electron ◽  
Two Phases ◽  
Nial Matrix

Small additions of Hf to NiAl produce a significant increase in the high-temperature strength of single crystals. Hf has a very limited solubility in NiAl and in the presence of Si, results in a high density of G-phase (Ni16Hf6Si7) cuboidal precipitates and some G-platelets in a NiAl matrix. These precipitates have a F.C.C structure and nucleate on {100}NiAl planes with almost perfect coherency and a cube-on-cube orientation-relationship (O.R.). However, G-phase is metastable and after prolonged aging at high temperature dissolves at the expense of a more stable Heusler (β'-Ni2AlHf) phase. In addition to these two phases, a third phase was shown to be present in a NiAl-0.3at. % Hf alloy, but was not previously identified (Fig. 4 of ref. 2 ). In this work, we report the morphology, crystal-structure, O.R., and stability of this unknown phase, which were determined using conventional and analytical transmission electron microscopy (TEM).Single crystals of NiAl containing 0.5at. % Hf were grown by a Bridgman technique. Chemical analysis indicated that these crystals also contained Si, which was not an intentional alloying addition but was picked up from the shell mold during directional solidification.

The stabilization of B.C.C. Cu in Cu/Nb nanolayered composites

1996 ◽  
Vol 54 ◽  
pp. 228-229
Author(s):  
H. Kung ◽  
A.J. Griffin ◽  
Y.C. Lu ◽  
K.E. Sickafus ◽  
T.E. Mitchell ◽  
...  
Keyword(s):  
Electrical Resistivity ◽  
Layer Thickness ◽  
Volume Fraction ◽  
Ion Beam ◽  
High Strength ◽  
Cross Sectional ◽  
Metastable Structure ◽  
High Resolution Tem ◽  
Potential Improvement ◽  
Two Phases

Materials with compositionally modulated structures have gained much attention recently due to potential improvement in electrical, magnetic and mechanical properties. Specifically, Cu-Nb laminate systems have been extensively studied mainly due to the combination of high strength, and superior thermal and electrical conductivity that can be obtained and optimized for the different applications. The effect of layer thickness on the hardness, residual stress and electrical resistivity has been investigated. In general, increases in hardness and electrical resistivity have been observed with decreasing layer thickness. In addition, reduction in structural scale has caused the formation of a metastable structure which exhibits uniquely different properties. In this study, we report the formation of b.c.c. Cu in highly textured Cu/Nb nanolayers. A series of Cu/Nb nanolayered films, with alternating Cu and Nb layers, were prepared by dc magnetron sputtering onto Si {100} wafers. The nominal total thickness of each layered film was 1 μm. The layer thickness was varied between 1 nm and 500 nm with the volume fraction of the two phases kept constant at 50%. The deposition rates and film densities were determined through a combination of profilometry and ion beam analysis techniques. Cross-sectional transmission electron microscopy (XTEM) was used to examine the structure, phase and grain size distribution of the as-sputtered films. A JEOL 3000F high resolution TEM was used to characterize the microstructure.

Direct imaging of order-disorder and antiphase domain structures in Ti3Al intermetallic compound

1990 ◽  
Vol 48 (4) ◽  
pp. 480-481
Author(s):  
H. Q. Ye ◽  
T.S. Xie ◽  
D. Li
Keyword(s):  
Intermetallic Compound ◽  
Volume Fraction ◽  
Fundamental Problem ◽  
Antiphase Domain ◽  
Atomic Scale ◽  
Orientation Relationships ◽  
Domain Structures ◽  
Α Phase ◽  
Diffraction Patterns ◽  
Two Phases

The Ti3Al intermetallic compound has long been recognized as potentially useful structural materials. It offers attractive strength to weight and elastic modulus to weight ratios. Recent work has established that the addition of Nb to Ti3Al ductilized this compound. In this work the fundamental problem of this alloy, i.e. order-disorder and antiphase domain structures was investigated at the atomic scale.The Ti3Al+10at%Nb alloys used in this study were treated at 1060°C and then aged at 700°C for 2 hours. The specimens suitable for TEM were prepared by standard jet electrolytic-polishing technique. A JEM-200CX electron microscope with an interpretable resolution of about 0.25 nm was used for HREM.The [100] and [001] projections of the α2 phase were shown in Fig.l.The alloy obtained consist of at least two phases-α2(Ti3Al) and β0 structures. Moreover, a disorder α phase with small volume fraction was also observed. Fig.2 gives [100] and [001] diffraction patterns of the α2 phase. Since lattice parameters of the ordered α2 (a=0.579, c=0.466 nm) and disorder α phase (a0=0.294≈a/2, c0=0.468 nm) are almost the same, their diffraction patterns are difficult to be distinguished when they are overlapped with epitaxial orientation relationships.

The Free Responsible Action of the Individual

2018 ◽  
Author(s):  
Michael P. DeJonge
Keyword(s):  
The Novel ◽  
Extreme Situation ◽  
The Third ◽  
Third Phase ◽  
Responsible Action ◽  
Action Type ◽  
Two Phases ◽  
The Individual ◽  
The Church

If, as Chapter 12 argues, much of Bonhoeffer’s resistance thinking remains stable even as he undertakes the novel conspiratorial resistance, what is new in his resistance thinking in the third phase? What receives new theological elaboration is the resistance activity of the individual, which in the first two phases was overshadowed by the resistance role played by the church. Indeed, as this chapter shows, Bonhoeffer’s conspiratorial activity is associated with what he calls free responsible action (type 6), and this is the action of the individual, not the church, in the exercise of vocation. As such, the conspiratorial activity is most closely related to the previously developed type 1 resistance, which includes individual vocational action in response to state injustice. But the conspiratorial activity differs from type 1 resistance as individual vocational action in the extreme situation.

Finite Element Model to Predict the Bioconversion Rate of Glucose to Fructose using Escherichia coli K12 for Sugar Production from Date

2015 ◽  
Vol 11 (1) ◽  
pp. 105-113 ◽  
Author(s):  
Maher Trigui ◽  
Karim Gabsi ◽  
Walid Zneti ◽  
Suzelle Barrington ◽  
Ahmed Noureddine Helal
Keyword(s):  
Escherichia Coli ◽  
Induction Time ◽  
Volume Fraction ◽  
Element Model ◽  
Initial Concentration ◽  
Computational Fluids Dynamics ◽  
Date Syrup ◽  
Computational Fluids ◽  
Two Phases ◽  
Inoculum Volume

Abstract In this study, Bioconversion process of glucose to fructose from date syrup using Escherichia coli K12 is modeled using a commercial computational fluids dynamics (CFD) code fluent FLUENT 6.3.23 [8] which we implemented a user-defined functions (UDF) to simulate the interrelationships at play between various phases. A two phases CFD model was developed using an Eulerian – Eulerian approach to calculate the fructose volume fraction produced during time. The bioconversion process was studied as function of three initial concentration of glucose (0.14, 0.242 and 0.463gL–1), three induction time (60, 120 and 180 mn) and three inoculum volume (100, 120 and 150mL). The numerical results are compared with experimental data for bioconversion rate and show good agreement (R2= 0.894). The optimal condition of diffusion was obtained by applying an initial concentration of glucose less than 0.2gL–1 and induction time great than 100 minutes.

Magnetic Characterization of SUS316L Deformed by High Pressure Torsion

2011 ◽  
Vol 239-242 ◽  
pp. 1300-1303
Author(s):  
Hong Cai Wang ◽  
Minoru Umemoto ◽  
Innocent Shuro ◽  
Yoshikazu Todaka ◽  
Ho Hung Kuo
Keyword(s):  
Plastic Deformation ◽  
High Pressure ◽  
Stainless Steel ◽  
Phase Transformation ◽  
Austenitic Stainless Steel ◽  
Volume Fraction ◽  
High Pressure Torsion ◽  
Austenitic Matrix ◽  
Magnetic Characterization

SUS316L austenitic stainless steel was subjected to severe plastic deformation (SPD) by the method of high pressure torsion (HPT). From a fully austenitic matrix (γ), HPT resulted in phase transformation from g®a¢. The largest volume fraction of 70% a¢ was obtained at 0.2 revolutions per minute (rpm) while was limited to 3% at 5rpm. Pre-straining of g by HPT at 5rpm decreases the volume fraction of a¢ obtained by HPT at 0.2rpm. By HPT at 5rpm, a¢®g reverse transformation was observed for a¢ produced by HPT at 0.2rpm.

A Novel Processing Route for the Fabrication of Monolithic and Composite Silicon Nitride

1992 ◽  
Vol 287 ◽  
Author(s):  
R. V. Raman ◽  
S. V. Rele
Keyword(s):  
Volume Fraction ◽  
Hot Isostatic Pressing ◽  
Thermal Exposure ◽  
Processing Route ◽  
Promising Alternative ◽  
Α Phase ◽  
Key Issues ◽  
Novel Processing ◽  
Composite Silicon

ABSTRACTCurrent hot isostatic consolidation methodology used for the fabrication of complex-shaped Si3N4-based components requires the use of an expensive glass encapsulation technique and extended thermal exposure (in hours) of the specimen. An alternative consolidation approach involving the use of solid pressure transmitting media under high pressure, has enabled the consolidation of Si3N4 alloys without the need for glass encapsulation.Characterization of microstructures and mechanical properties of this (MOR, fracture toughness) material has been carried out and will be presented. It has been noted that in Si 3N4/8%Y2O3-4%Al2O3 composition, consolidated using this approach, a significantly larger volume fraction of α phase has been retained compared with typically observed conversion in α⇒ β in hot isostatically pressed material or sintered material.Key issues for addressing densification and microstructure control using this process are presented. This rapid consolidation approach appears to be a promising alternative to hot isostatic pressing for the fabrication of complex-shaped Si3N4 components.

scholarly journals Surface and Underground Geomechanical Characterization of an Area Affected by Instability Phenomena in Zaruma Mining Zone (Ecuador)

2021 ◽  
Vol 13 (6) ◽  
pp. 3272
Author(s):  
Paúl Carrión-Mero ◽  
Maribel Aguilar-Aguilar ◽  
Fernando Morante-Carballo ◽  
María José Domínguez-Cuesta ◽  
Cristhian Sánchez-Padilla ◽  
...  
Keyword(s):  
Mass Movement ◽  
Mining Activity ◽  
Mining District ◽  
Mean Values ◽  
Surface Areas ◽  
Definition Of ◽  
Action Measures ◽  
Geomechanical Characterization ◽  
The City

In the last decade, in the mining district of Zaruma-Portovelo, there has been significant land subsidence related to uncontrolled mining activity. The purpose of this work was to carry out a surface and underground geomechanical characterization of a mining sector north of the city of Zaruma that allows the definition of potentially unstable areas susceptible to the mass movement. The methodology used consists of the following stages: (i) compilation of previous studies; (ii) surface and underground characterization of rocky material to establish its susceptibility to mass movement; (iii) interpretation of results; and (iv) proposal of action measures. Among the most relevant results, it stands out that 26.1% of the 23 stations characterized on the surface present conditions that vary from potentially unstable to unstable. In underground galleries, the studied mean values of the 17 stations indicate that the rock has a medium to good quality, representing a medium susceptibility to gallery destabilization. The results obtained for the surface areas (depths up to 50 m, where altered materials predominate) and the underground areas (depths > 50 m, where the alterations are specific) can be used to identify the areas with a more significant potential for instability. For both cases, it has been possible to define specific monitoring, control, and planning actions for sensitive areas.

Estimation of Interlayer Thickness in Inorganic Particulate-Filled Polymer Composites

2011 ◽  
Vol 24 (6) ◽  
pp. 777-788 ◽  
Author(s):  
J.Z. Liang
Keyword(s):  
Polymer Composites ◽  
Volume Fraction ◽  
Particle Diameter ◽  
Interfacial Structure ◽  
Interlayer Thickness ◽  
Filled Polymer ◽  
Mechanical And Physical Properties ◽  
The Relationship ◽  
Good Agreement

The structure of the interlayer between matrix and inclusions affect directly the mechanical and physical properties of inorganic particulate-filled polymer composites. The interlayer thickness is an important parameter for characterization of the interfacial structure. The effects of the interlayer between the filler particles and matrix on the mechanical properties of polymer composites were analyzed in this article. On the basis of a simplified model of interlayer, an expression for estimating the interlayer thickness ([Formula: see text]) was proposed. In addition, the relationship between the [Formula: see text] and the particle size and its concentration was discussed. The results showed that the calculations of the [Formula: see text] and thickness/particle diameter ratio ([Formula: see text]) increased nonlinearly with an increase of the volume fraction of the inclusions. Moreover, the predictions of [Formula: see text] and the relevant data reported in literature were compared, and good agreement was found between them.

Sign in / Sign up

Export Citation Format

Share Document