Creep Cavitation Enhanced by Glass Pocket Formation in a Tetragonal Zirconia Doped with 0.3 WT% Pure Silica

1998 ◽  
Vol 539 ◽  
Author(s):  
K. Morita ◽  
K. Hiraga ◽  
Y. Sakka
Keyword(s):  
Grain Size ◽  
Glass Phase ◽  
Tetragonal Zirconia ◽  
Constant Stress ◽  
Cavity Formation ◽  
Phase Precipitation ◽  
Pure Silica ◽  
Creep Cavitation ◽  
Pocket Formation ◽  
The Relationship

AbstractThe relationship between intergranular microstructures and cavitation is examined in a yttria-stabilized tetragonal zirconia doped with 0.2-0.4 wt% SiO2 under constant stress loading in tension. An increase in the initial grain size for a constant SiO2-addition or an increase in SiO2-addition for a constant grain size enhances the precipitation of a glass phase at the multiple grain junctions during deformation. Simultaneously with the enhanced glass phase precipitation, intergranular cavitation is also enhanced. This is because the precipitated glass phase act as the site of cavity formation.

Variations in magnetic properties of Mexican serpentinites and related micro-textures 

2021 ◽  
Author(s):  
Sandra B. Ramírez-García ◽  
Luis M. Alva-Valdivia
Keyword(s):  
Grain Size ◽  
Magnetic Properties ◽  
Magnetic Susceptibility ◽  
Anisotropy Of Magnetic Susceptibility ◽  
Ultramafic Rocks ◽  
Magnetic Carrier ◽  
Temperature Dependent ◽  
Geochemical Studies ◽  
The Relationship ◽  
Magnetite Formation

<p>Magnetite formation of serpentinized ultramafic rocks leads to variations in the magnetic properties of serpentinites; however, magnetite precipitation is still on debate.</p><p>In this work, we analyzed 60 cores of ultramafic rocks with a variety of serpentinization degrees. These rocks belong to the ultramafic-mafic San Juan de Otates complex in Guanajuato, Mexico. Geochemical studies have been previously conducted, enabling us to compare changes in the magnetic properties against the chemical variations generated by the serpentinization process. By studying the density and magnetic properties such as anisotropy of magnetic susceptibility, hysteresis curves as well as magnetic and temperature-dependent susceptibility and, we were able to identify the relationship between magnetic content and serpentinization degree, the predominant magnetic carrier, and to what extent the magnetite grain size depends on the serpentinization.  Variations in these parameters allowed us to better constrain the temperature at which serpentinization occurred, the generation of other Fe-rich phases such as Fe-brucite and/or Fe-rich serpentine as well as distinctive rock textures formed at different serpentinization degrees.</p>

Analytical Treatment of Field-Effect Conduction in Polysilicon thin film Transistors

1997 ◽  
Vol 471 ◽  
Author(s):  
W. Eccleston
Keyword(s):  
Thin Film ◽  
Grain Size ◽  
Thin Film Transistors ◽  
Field Effect ◽  
Drain Current ◽  
High Current ◽  
Analytical Treatment ◽  
Channel Mobility ◽  
Current Region ◽  
The Relationship

ABSTRACTThe drift of electrons in the channels of Thin Film Transistors is analysed for discrete grains separated by grain boundaries containing amorphous silicon. The model provides the relationship channel mobility and grain size. The relationship between drain current and the terminal voltages is also predicted. The model relates to normal high current region of transistor operation.

scholarly journals Characterization of sand boils with grading entropy

2012 ◽  
pp. 73-88
Author(s):  
Laslo Nadj
Keyword(s):  
Grain Size ◽  
Distribution Curve ◽  
Practical Consideration ◽  
Implicit Information ◽  
Sand Boil ◽  
Sand Boils ◽  
Grain Distribution ◽  
Soil Behaviour ◽  
The Relationship

Grain size and grain distribution by size are dominant factors determining soil behaviour. The shape and position of a grain distribution curve contain implicit information about the propensity of sand boiling or piping at flood conditions. The author used 1040-grain distribution curves taken from 12 sand boil locations to study the relationship between sand boils, hydraulic soil failures and entropy. The results have justified the hypotheses and indicated some fairly important details for practical consideration. Calculating grain distribution entropy is not ?magic? with mathematics: it simply helps put the expected behaviour of soils into a different perspective and promotes orientation for classifying soils according to a new parameter related to grain movement.

Lower air-crystallization temperature and nanostructured yttria-doped tetragonal zirconia polycrystals ceramics by seeding assisted chemical coprecipitation

1999 ◽  
Vol 14 (5) ◽  
pp. 1686-1689 ◽  
Author(s):  
P. Durán ◽  
J. Tartaj ◽  
J. F. Fernández ◽  
C. Moure
Keyword(s):  
Grain Size ◽  
Crystallization Temperature ◽  
Tetragonal Zirconia ◽  
Nanocrystalline Powder ◽  
Chemical Coprecipitation ◽  
Seed Particles

The crystallization temperature of yttria-doped tetragonal zirconia polycrystals (Y-TZP) amorphous precursors can be lowered 150 °C below that currently used (≥500 °C), if “seeding assisted chemical coprecipitation” is used. Completely crystallized Y-TZP nanocrystalline powder was obtained by calcining at 350 °C in air; the Y-TZP precursors seeded with 10 wt% of nanometric (∼8 nm) Y-TZP particles. The seed particles enhanced both the nucleation and the crystallization rates at lower temperatures. From such a powder, 99% dense and nanostructured (grain size, <90 n m) Y-TZP bodies can be prepared by sintering below 1050 °C.

Microstructural Design for Attaining High-Strain-Rate Superplasticity in Oxide Materials

2006 ◽  
Vol 45 ◽  
pp. 923-932
Author(s):  
Keijiro Hiraga ◽  
Byung Nam Kim ◽  
Koji Morita ◽  
Tohru Suzuki ◽  
Yoshio Sakka
Keyword(s):  
Grain Size ◽  
High Strain Rate ◽  
Strain Rate ◽  
High Strain ◽  
Spinel Phase ◽  
Tetragonal Zirconia ◽  
Secondary Phases ◽  
Cavitation Damage ◽  
Size Refinement ◽  
Dynamic Grain Growth

Factors limiting the strain rate of superplastic deformation in oxide ceramics are discussed from existing knowledge about the mechanisms of high-temperature plastic deformation and intergranular cavitation. The discussion leads to the following guide: simultaneously controlling the initial grain size, diffusivity, dynamic grain growth, homogeneity of microstructure and the number of residual defects is essential to attain high-strain-rate superplasticity. Along this guide, high-strain-rate superplasticity (HSRS) is attainable in some oxides consisting of tetragonal zirconia, α-alumina and a spinel phase: tensile ductility reached 300-2500% at a strain rate of 0.01-1.0 s-1. Post-deformation microstructure indicates that some secondary phases may suppress cavitation damage and thereby enhance HSRS. The guide is also essential to lower the limit of deformation temperature for a given strain rate. In monolithic tetragonal zirconia, grain-size refinement combined with doping of aliovalnt cations such as Mg2+, Ti4+ and Al3+ led to HSRS at 1350 °C.

Thermodynamic Characteristics of Y2O3 and Y2S3 Nonmetallic Phase Formed in Liquid Steel

2020 ◽  
Vol 844 ◽  
pp. 9-23
Author(s):  
Sergii Gerasin ◽  
Dorota Kalisz ◽  
Jerzy Iwanciw
Keyword(s):  
Oxygen Content ◽  
Molten Steel ◽  
Liquid Steel ◽  
Thermodynamic Characteristics ◽  
Phase Precipitation ◽  
Low Oxygen ◽  
Metallic Oxide ◽  
Metal Bath ◽  
Metallic Inclusions ◽  
The Relationship

The current work deals the phenomenon of non-metallic inclusions as a result of the addition of Yttrium as an alloying component. The order of introducing individual components determines its final content in steel. This problem was analyzed using the WYK_Stal program developed at AGH-UST. Individual cases were considered using the accepted thermodynamics models based on Wagner’s formalism. The study of Y2O3 and Y2S3 phase precipitation and the relationship between the addition of Y, Al, Ca, O and S in molten steel was studied using the thermodynamic models. Based on the simulation, the authors stated that, the introduction of aluminum as the final deoxidizer into the liquid steel before the yttrium, results in the formation of non-metallic oxide inclusions. The low oxygen content in the metal bath promotes the formation of yttrium sulphide. In the case of calcium dosing, it is reasonable that, the yttrium is introduced after this element, which limits the losses on the formation of the yttrium sulphide phase.

Sign in / Sign up

Export Citation Format

Share Document