THE ROLE OF THE CHEMICAL ENVIRONMENT IN FRICTIONAL DEFORMATION - STRESS-CORROSION CRACKING AND COMMINUTION

The roles of chemically assisted crack and fracture propagation and ch emically assisted comminution in frictional deformation are evaluated in this study. Double cantilever beam (DCB) crack propagation data are presented which show that the role of pH in chemically assisted fract ure, and to a lesser extent the role of ionic concentration are import ant in stress corrosion cracking. Data on very slow crack growth and t he stress corrosion limit are also presented. These data suggest that stress corrosion cracking may play an important role in compound earth quakes and in asperity breakdown in faults. The comminution literature is also reviewed in order to assess the role of chemically assisted c omminution in frictional deformation. It appears that chemically assis ted comminution may be important at low and high ionic strength becaus e it may reduce the effective viscosity and the shear strength of faul t gouge. At intermediate ionic concentration the role of pH, as an age nt which enhances crack and fracture propagation, appears to be more i mportant in reducing the coefficient of sliding friction.