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Fracto‐emission during Fracture of Engineering Ceramics
Author(s) -
Enomoto Yuji,
Chaudhri M. Munawar
Publication year - 1993
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1151-2916.1993.tb03984.x
Subject(s) - electron , fracture (geology) , materials science , charpy impact test , ionization , ceramic , field electron emission , electrode , composite material , atomic physics , electric field , ion , chemistry , physics , nuclear physics , microstructure , organic chemistry , quantum mechanics
An experimental study of the emission of fracto‐electrons from engineering ceramics, such as Al 2 O 3 , ZrO 2 , Al 2 O 3 /ZrO 2 , and Si 3 N 4 , has been made under ambient atmospheric conditions when they were fractured with an indenter mounted on the arm of a Charpy impact machine or by a power press machine. In these experiments, the indenter, made of a hard electro‐conductive material, acted as an electrode to collect the emitted electrons; the collected electrons were fed into a high‐sensitivity charge amplifier. The results obtained showed that, when the test specimen fractured, fracto‐electrons were emitted. This was confirmed by the simultaneous appearance of the electrical and acoustical signals. The total charge collected varied in the range of 10 −11 –10 −9 C, depending on the fracture mode, fracture load, and the nature of the gaseous environment. The fracture surfaces of the specimens were found to be electrified, reaching potentials of the order of a few hundred volts. We believe that the origin of the fracto‐emission of electrons is the separation of the charges on the fracturing surfaces, which leads to the formation of an electric field and the liberation of exoelectrons; these electrons are of sufficiently high energies to cause the ionization of the ambient gaseous atoms/molecules.