Subsurface Zones in Steel Samples Studied by Means of Positron Annihilation

This paper presents the results of positron beam experiments performed on raw steel samples whose surfaces have been damaged during sliding contact in the conventional pin-on-disc tribotest. It was important to use raw samples, because we were examining the usefulness of the positron beam in technical applications where such samples could be available. We were able to detect a change of experimental parameters, i.e., the positron diffusion length related to the type of the lubricant used in the tribotest. The analysis of the S parameter on the surface did not suggest any characteristic changes which would prove the creation of the top layer of new properties induced by the friction process. To complete our studies, we also carried out studies by measurement of the positron annihilation characteristics in the conventional experiment.