Fracture and Contact Adhesion Energies of Mica‐Mica, Silica‐Silica, and Mica‐Silica Interfaces in Dry and Moist Atmospheres
作者:
Kai‐Tak Wan,
Douglas T. Smith,
Brain R. Lawn,
期刊:
Journal of the American Ceramic Society
(WILEY Available online 1992)
卷期:
Volume 75,
issue 3
页码: 667-676
ISSN:0002-7820
年代: 1992
DOI:10.1111/j.1151-2916.1992.tb07857.x
出版商: Blackwell Publishing Ltd
关键词: mica;silica;interfaces;fracture;adhesion
数据来源: WILEY
摘要:
A study is made of the factors that contribute to the energy of mica‐mica, silica‐silica, and mica‐silica interfaces in the presence of moist atmospheres. Energies are measured using brittle fracture and contact adhesion techniques. Both “virgin” and “healed” interfaces are investigated, with special attention on the latter. The fracture and adhesion data overlap, reflecting a common underlying separation process by “sharp‐crack propagation.” The study identifies several contributors to the interface adhesion energies. At virgin mica‐mica and silica‐silica interfaces the energy is determined by primary ionic‐covalent attraction, and by the screening of this attraction by condensed moisture from the atmosphere. At healed interfaces the energy depends on both environmental interaction and “lattice” coherence. At retracted cracks in mica‐mica most of the virgin ionic attraction is retained. On misorienting separated cleavage halves prior to recontact the interaction energy drops substantially: in “dry” atmosphers (relative humidity50%) capillary forces dominate. The dissimilar mica‐silica system exhibits the same dominance by capillary forces in wet atmospheres. However, in dry atmospheres the adhesion energy becomes inordinately high, from spontaneous transfer of electronic charge from one surface to the other. The implications of these observations concerning mechanic
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