期刊
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
卷 55, 期 25-26, 页码 8129-8138出版社
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.ijheatmasstransfer.2012.08.054
关键词
Porosity; Pore formation; Solidification defect; Phase change; Pore shape; Bubble capture; Bubble entrapment
资金
- National Science Council, Taiwan, Republic of China [NSC 97-2221-E-110-071-MY3]
Development of the pore shape from a tiny bubble captured by a solidification front is fundamentally and systematically investigated in this study. Pore formation and its shape in solid influence not only microstructure of materials, but also contemporary issues of various sciences of biology, engineering, foods, geophysics and climate change, etc. In this work, the tiny bubble cap beyond the solidification front is considered to be spherical. As the dominant parameter, the bubble growth rate-solidification rate ratio, decreases, contact angle is found to approach 90 degrees. An accepted criterion, stating that a pore becomes closed as long as the solidification rate is greater than bubble growth rate, is incorrect. This study also finds that the pore can be closed if the bubble radius at contact angle of 90 degrees exhibits a local minimum. Since contact angle of 90 degrees can maintain for a period of time, a subsequent positive bubble growth rate-to-solidification rate ratio readily gives rise to an isolated pore. The pore can be elongated, expanded, shrunk, rippled or closed, depending on the bubble growth rate-to-solidification rate ratio. Manipulating the bubble growth rate or solidification rate to control the pore shape in solid is therefore provided. (C) 2012 Elsevier Ltd. All rights reserved.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据