Tribochemical wear theory of non-oxide ceramics in high temperature and high-pressure water

Tribochemical wearing in S-C mylonites and its implication to lithosphere stress level

“…This difference influences the hardness H of their materials. Tanaka et al (1989) found the Vickers hardness of ionic-type oxide ceramics (silicates) is a factor of 2∼3 smaller than that of covalent type non-oxide ceram- Kitaoka et al (1997) Tribochemical oxidation (wet) 21 Silicon carbide Kitaoka et al (1997) ics; presumably these properties of rocks would be important yet difficult to determine in natural example. Thus, this hardness reduction would lower the stress estimation for Eq.…”

“…As a consequence, a chemical process also takes place within the minor shear zone during 'cataclasite' formation, in the presence of water. Under these wet conditions, a tribochemical wear theory (Kitaoka et al, 1997) should be applied to a wear process at seismogenic depths because the theory involves the production of an amorphous silicon oxide coated-layer on the contact asperity due to frictional heat, in the presence of water. The amorphous silicon oxide layer has been observed on the slip surface of quartz and natural fault gouge after sliding (Moody and Hundley-Goff, 1980;Yund et al, 1990).…”

“…However, this traditional model does not involve the interaction of frictional and chemical processes that must be required during frictional sliding in the presence of water (Fischer and Mullins, 1994;Zhao et al, 1996). (Kitaoka et al, 1997) and rocks (Yoshioka, 1986 Thus, we apply a new tribochemical wear theory (Kitaoka et al, 1997) to the seismogenic frictional process. Although the traditional models involve only failures of contact junctions, the wear theory involves the production of an amorphous silicon oxide coated-layer on the contact asperity due to frictional heat.…”

“…The amorphous oxide layer is removed when the adjacent asperities rupture contact junctions, resulting in further oxidation on the fresh surface. Kitaoka et al (1997) proposed a theoretical equation for a tribochemical wear of non-oxide ceramics in high-temperature and high-pressure water on the basis of the interface reaction of real contact area due to friction:…”

“…For a quantitative estimation, Table 1 summarizes constitutive variables of Eq. (3) from frictional experiments of non-oxide ceramics (Kitaoka et al, 1997) and rocks (Yoshioka, 1986). Evans (1990) documented that W -D relations for brittle 'cataclasite' exhibit no linear correlation because they are influenced by various factors, such as fault types, bedrock lithologies, degree of exhumation, and activity of faults.…”