Tribocorrosion of stainless steels

To research tribocorrosive processes a test instrument was developed which allows the simultaneous recording of tribological and electrochemical characteristica in aggressive solutions with solid particles. Therefore the stainless steels X5Cr12, X30Cr12 and X5CrNi25-6 were moved oscillating in quartz containing sodium sulphate solution and sulphuric acid with a definite surface pressure over a period of 16 h. Corrosion potential-time curves, current transients taken at a constant potential and current density-potential curves were carried out with and without mechanical load to characterize the electrochemical system. The surface removal rates were determined from the mass loss at free corrosion and at polarization in the passive region. These data were compared with those of only corrosion and only wear. So it was possible to determine the electrochemical part of the tribocorrosion process and to calculate the mechanical one. With help of the concept of Matsumura and Oka [18] synergetic effects could be calculated. The total synergism was determined for three steels in two different solutions and at two different potentials.