Evaluation of Thermal Sprayed Corrosion Protection Systems on Cast Materials for Use in Marine Power Plants

Although having high potentials, marine power plants are currently still rarely used. Yet, tidal, current and wave power plants are coming more into focus due to long European coastlines and high degree of planning reliability. One of the current cost drivers is the scaling and durability of the widely utilized ductile cast iron materials. Due to their good mechanical properties and comparatively low costs, they are used in a wide range of fatigue-stressed components such as bearing housings or flanges. Due to direct contact with seawater, the cast components are generally sealed with organic coatings and in some cases protected with sacrificial anodes. Since these methods, however, are not durable over a long time, free corrosion of the components occurs, lowering fatigue strength significantly. This leads to huge corrosion additions in the operational strength assessment in the design phase. Hence, in a recent project, thermal sprayed coatings based on Al, Zn, pseudo alloys thereof and Cu are applied to cast materials subject to fatigue stress to prevent corrosion and conserve long-term fatigue strength. It is examined, if the fatigue behavior of the developed coating systems can also be tolerated in the context of salt water interaction and after occurring damages.