Thermally sprayed coatings with stochastic microstructures for thermomechanically high stressed surfaces

摘要

New requirements for modern component part surfaces increasingly demand improvements over friction coefficients in the sense of a reduction of friction losses. A substantial control factor in terms of lower friction and wear is the use of coating solutions such as thermal spray coatings. In practice, the application of coatings by means of thermal spray is more and more often used for influencing tribological matching. However, surface microstructuring might represent an additional, further reaching solution for wear and friction behaviour improvements of tribologically high-stressed surfaces. The aim of the reported research project is the development of atmospheric plasma sprayed (APS) coatings with an inherent porous microstructure and surfaces with stochastically distributed nap volumes (from cut pores) regarding lubricant retention and -distribution in running surfaces of friction-type bearings. Subject of these investigations are in particular thermomechanically highly loaded hydrodynamic tribological matchings, amongst others by the example of a piston ring/cylinder system in engine blocks. The use of special fractioned Fe-base powders enables the production of a new type of coatings with an inherent porous microstructure, which offer advantages due to constantly regenerating their surface topology under wear, and maintain employment in tribological systems with increased loads due to optimized lubricant retention and distribution. Hence, this project has an emphasis on the design of optimal nap sizes in coating surface structure in dependence on the hydrodynamical load, as well as on investigations for the controllability of nap volumes by the design of suitable processes.