Pore Formation in Solid

2012 ◽  
Vol 28 (1) ◽  
pp. 1-6
Author(s):  
P. S. Wei ◽  
S. Y. Hsiao ◽  
S. S. Hsieh
Keyword(s):  
Solidification Front ◽  
Pore Formation ◽  
Three Dimensional ◽  
Pore Shape ◽  
Critical Factors ◽  
Dissolved Gas ◽  
Factors Affecting ◽  
Working Parameters ◽  
Realistic Prediction ◽  
Perturbation Solutions

ABSTRACTThe shapes of a growing or decaying bubble entrapped by a solidification front are predicted in this work. The bubble results from supersaturation of a dissolved gas in the liquid ahead of the solidification front. Pore formation and its shape in solid are one of the most critical factors affecting properties, microstructure, and stresses in materials. In this study, the bubble and pore shapes entrapped in solid can be described by a three-dimensional phase diagram, obtained from perturbation solutions of Young-Laplace equation governing the tiny bubble shape in the literature. The predicted growth and entrapment of a microbubble as a pore in solid are found to agree with experimental data. This work thus provides a realistic prediction of the general growth of the pore shape as a function of different working parameters.

A Model to Predict Pore Shape in Solid During Solidification

2009 ◽  
Author(s):  
S. Y. Hsiao ◽  
P. S. Wei
Keyword(s):  
Solidification Front ◽  
Pore Formation ◽  
Mass Conservation ◽  
Bubble Surface ◽  
Time Dependent ◽  
Dissolved Gas ◽  
Chemical Equilibria ◽  
Physico Chemical ◽  
Perturbation Solutions

The shapes of a growing or decaying bubble entrapped by a solidification front are predicted in this work. The bubble results from supersaturation of a dissolved gas in the liquid ahead of the solidification front. Pore formation is one of the most serious issues affecting properties, microstructure, and strength in materials. In this study, the bubble entrapped as a pore in solid are realistically predicted by utilizing perturbation solutions of Young-Laplace equation governing the tiny bubble shape in the literature. The analytical solutions can account for necking of a bubble beyond the solidification front. Satisfying energy, momentum, mass conservation and physico-chemical equilibria on the bubble surface, the predicted time-dependent pore shapes are found to agree with in-situ measurements.

Effects of Bubble Growth and Solidification Rate on Pore Formation in Solid

2012 ◽  
Author(s):  
P. S. Wei ◽  
S. Y. Hsiao
Keyword(s):  
Growth Rate ◽  
Contact Angle ◽  
Solidification Front ◽  
Bubble Growth ◽  
Pore Formation ◽  
Solidification Rate ◽  
Bubble Radius ◽  
Abel Equation ◽  
Spherical Cap ◽  
Factors Affecting

The shapes of a pore in solid resulted from entrapment of a tiny bubble by a solidification front are predicted in this work. Pore formation and its shape in solid are one of the most critical factors affecting properties and microstructure, in materials. For simplicity without loss of generality, the tiny bubble is considered to have a spherical cap. From a geometrical analysis, the contact angle of the bubble cap on the solidification front or the pore shape in solid is found to be governed by the Abel equation of the first kind. The pore becomes closed by imposing a finite bubble growth rate-to-solidification rate ratio which can produce a minimal bubble radius at the contact angle of 90 degrees. Closure of a pore resulted from a greater solidification rate than bubble growth rate, as accepted in the literature, is incorrect.

Application of Automated FIB for TEM Sample Preparation in Semiconductor Failure Analysis

2014 ◽  
Author(s):  
Jie Zhu ◽  
Soo Sien Seah ◽  
Irene Tee ◽  
Bing Hai Liu ◽  
Eddie Er ◽  
...  
Keyword(s):  
Sample Preparation ◽  
Success Rate ◽  
Protective Layer ◽  
Factors Affecting ◽  
Dual Beam ◽  
Lamella Thickness ◽  
Surface Patterns ◽  
Working Parameters ◽  
Practical Factors ◽  
High Flexibility

Abstract In this paper, we describe automated FIB for TEM sample preparation using iFast software on a Helios 450HP dual-beam system. A robust iFast automation recipe needs to consider as many variables as possible in order to ensure consistent sample quality and high success rate. Variations mainly come from samples of different materials, structures, surface patterns, surface topography and surface charging. The recipe also needs to be user-friendly and provide high flexibility by allowing users to choose preferable working parameters for specific types of samples, such as: grounding, protective layer coating, milling steps, and final TEM lamella thickness/width. In addition to the iFast recipe, other practical factors affecting automation success rate are also discussed and highlighted.

scholarly journals Exploring the Critical Factors, the Online Learning Continuance Usage during COVID-19 Pandemic

2021 ◽  
Vol 13 (10) ◽  
pp. 5471
Author(s):  
Chuan-Yu Mo ◽  
Te-Hsin Hsieh ◽  
Chien-Liang Lin ◽  
Yuan Qin Jin ◽  
Yu-Sheng Su
Keyword(s):  
Online Learning ◽  
Technology Acceptance ◽  
Family Support ◽  
Technology Acceptance Model ◽  
Online Teaching ◽  
Ease Of Use ◽  
Critical Factors ◽  
Factors Affecting ◽  
E Learning ◽  
Acceptance Model

In order to enable online learning to continue developing when the COVID-19 pandemic passes, this study aimed to identify the critical factors that affected the use of e-learning by university students during the pandemic. These critical factors will help to increase the efficiency of future development and deployment of online learning systems. Through a literature review, this study employed the technology acceptance model, social support, and task–technology fit as the theoretical basis to establish the framework of the online learning environment with regards to the technology acceptance model in the context of emergency management. A questionnaire survey was administered to students in universities that had implemented online teaching during the pandemic, and 552 valid responses were collected. The survey explored the factors affecting the willingness of higher education institution students to continue using online learning, and the following conclusions were drawn. (1) The easier an online learning platform was to navigate, the better it was perceived by the students, and thus the students were more willing to use it. (2) Ease of use and usefulness were associated with the teachers’ choice of platform and their ability to achieve a satisfactory fit between the course design and platform navigation, which thereby affected the students’ learning outcomes and attitude towards use. (3) The positive attitude of teachers towards teaching increased the students’ perceived ease of use of online learning. (4) During the pandemic, family support—a major support for teachers in online teaching—enhanced teachers’ attitudes towards, and willingness to provide, online teaching. A high level of support showed that the parents urged the students to learn and complete online learning tasks as instructed by the teachers, implying that family support could affect the students’ habits towards, adaptation to, and identification of online learning. The study results provide insights into the factors affecting the willingness of teachers and students to continue using e-learning platforms.

scholarly journals Porous Characteristics of Three-Dimensional Disordered Graphene Networks

Crystals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 127
Author(s):  
YongChao Wang ◽  
YinBo Zhu ◽  
HengAn Wu
Keyword(s):  
Pore Size ◽  
Low Temperatures ◽  
Gas Adsorption ◽  
Three Dimensional ◽  
Md Simulations ◽  
Structural Features ◽  
Atomic Scale ◽  
Critical Factors ◽  
Chlorination Process ◽  
Porous Morphology

The porous characteristics of disordered carbons are critical factors to their performance on hydrogen storage and electrochemical capacitors. Even though the porous information can be estimated indirectly by gas adsorption experiments, it is still hard to directly characterize the porous morphology considering the complex 3D connectivity. To this end, we construct full-atom disordered graphene networks (DGNs) by mimicking the chlorination process of carbide-derived carbons using annealing-MD simulations, which could model the structure of disordered carbons at the atomic scale. The porous characteristics, including pore volume, pore size distribution (PSD), and specific surface area (SSA), were then computed from the coordinates of carbon atoms. From the evolution of structural features, pores grow dramatically during the formation of polyaromatic fragments and sequent disordered framework. Then structure is further graphitized while the PSD shows little change. For the obtained DGNs, the porosity, pore size, and SSA increase with decreasing density. Furthermore, SSA tends to saturate in the low-density range. The DGNs annealed at low temperatures exhibit larger SSA than high-temperature DGNs because of the abundant free edges.

Critical factors affecting the planning and implementation of major projects

1993 ◽  
Vol 14 (5) ◽  
pp. 319-337 ◽  
Author(s):  
John M. Bryson ◽  
Philip Bromiley
Keyword(s):  
Critical Factors ◽  
Factors Affecting
Sign in / Sign up

Export Citation Format

Share Document