Corrosion Resistant Coatings for Cylinder Bore Applications in Passenger Car Engines

In this study, two high-Cr stainless steel feedstocks and a post-spray honing process are evaluated for potential use on cylinder running surfaces in passenger car engines. The two materials, X12 CrNi 25-4 and X6 Cr17, were deposited by plasma transferred wire arc (PTWA) spraying on aluminum cylinder bore surfaces that were mechanically roughened prior to coating. The coatings were then honed to a mirror finish using progressively finer diamond tools. Coating surfaces were analyzed by SEM and REM imaging, roughness profiles were recorded, and coating hardness and porosity were measured. The results are presented and discussed along with recommendations for additional work.