This article intends to describe a typical CrN Physical Vapor deposited hard coating used for piston ring application and compare it with different structured CrN PVD coatings, in regard to coating performance. Due to the harsh environment conditions of a piston ring during engine life this component requires thick, wear resistant coatings to meet the high durability requirements. Besides, the coating should present high delamination resistance, which is associated with resistance to thermal and contact fatigue. CrN has been successful in the field since it started to be used with 30 to 40 microns thick coatings on rings. Nevertheless, due to the increasing combustion pressure and reduced lubrication oil availability, additional toughness is being required to avoid damage of the running face at the ring. In that sense, various CrN structures were investigated and discussed: CrN low stress, CrN multilayer and CrN/Cr multilayer. Evaluation of the structured CrN coatings was done by metallurgical evaluation, bench test and scratch test. The engineered CrN PVD coatings presented in this work were obtained by varying process parameters, resulting in coatings with different mechanical properties.
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