INVESTIGATION OF THE SURFACE FATIGUE OF CARBIDE COMPOSITES AND PVD HARD COATINGS

摘要

Surface fatigue testing have been carried out on a range of carbide composites and PVD (physical vapor deposition) hard coatings using an impact loading equipment. Results have confirmed the theoretical methodology of testing method by repeated loading of specimens with ball indenter of defined radius and constant maximum load. The precise prediction of surface fatigue life (N_f) for carbide composites has been done. An attempt of results interpretation is presented in order to predict the surface fatigue limit (σ_(sf)) of studied materials. The dramatic increase of plastically deformed zone dimensions under indent after high cycle fatigue is observed. The fractographical investigations of subsurface layer of affected site revealed the specific mechanism of fatigue crack advancement.