Design of DLC coatings for high speed hybrid ball bearings

Diamond-like Carbon coatings (DLC) combine high wear resistance with low friction coefficients. At present, those coatings are developed mainly on an empirical basis as the basic coating characteristics as well as the real local loading conditions are rarely available. This paper presents some results of ongoing work concerning the assessment and design of coated surfaces of ball bearings. From the finite element modelling of the contact situation in a ball bearing as well as in fundamental material tests, hints for a straightforward optimization of the surface properties of the substrate and of the coating properties are derived. Following the resulting design recommendations the lifetime of coated bearings can be increased by a factor of 10