basis of this limited usefulness of the second type of research that the first group has claimed the superiority of its own methods, although the latter have also been known to be ineffective when confronted with highly complex, but realistic design problems.
A study i s 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 "sharpcrack propagation." The study identifies several contributors to the interface adhesion energies. At virgin micamica 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" atmospheres (relative humidity SO%) 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 mechanical properties of brittle ceramics are discussed.[
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.