Fatigue resistance of PECVD coated components

The thin hard coating deposition technologies CVD and PVD have been used for a long time in industry. Such coatings prove very effective in improving the tribological and corrosive resistant properties of the substrate. It was shown that the compressive residual stress that arise on the surface layer from some deposition processes also help to increase the fatigue limit of coated structural components. The aim of this work is to evaluate the effect of a SiOx coating, deposited by means of PECVD technology, on the fatigue resistance of a quenched and tempered alloy steel (39NiCrMo3). Rotating bending fatigue tests were carried out to asses its fatigue limit and characterize any possible variation between the coated and the uncoated material. Fracture surface observations were made using SEM on failure surfaces, and scratch tests were performed on samples to assess the coating-substrate interface delamination.