Influence of a hybrid treatment consisting of fine particle bombardment and powder impact plating on the scuffing behavior of ductile cast iron

The objective of this research was to determine the influence of applying a hybrid treatment, consisting of fine particle bombardment (FPB) and powder impact plating (PIP), on the scuffing behavior of ductile cast iron. Ductile cast iron samples were processed by an FPB treatment, a PIP treatment, and a hybrid treatment of both FPB and PIP. Scuffing behavior of these samples was investigated using block-on-ring tests. A piston alloy of ductile cast iron was used for the block and a cast iron cylinder alloy was used for the ring. Results showed that scuffing resistance depends on surface hardness and friction coefficient for the test samples. FPB treatment of block samples increases their surface hardness by nanocrystallization and reduces the friction coefficient of the tribological pair by reducing the surface roughness and producing a micro-dimpled surface. Thus, the scuffing resistance of FPB treated block is improved. The scuffing resistance is also improved by PIP treatment, which reduces the friction coefficient by producing a soft Sn film on the contact surface. After a hybrid treatment of both FPB and PIP, the surface hardness of the ductile cast iron substrate is increased and the friction coefficient of the tribological pair is further reduced relative to either single treatment. Therefore, hybrid treatments such as the ones described here can improve the scuffing resistance of cast irons.