Development of Resin Coated Piston suitable for Monolithic Cylinders made of Hypereutectic Al-Si Alloy 2022-32-0010

This study focuses on improving durability of the resin coated piston developed especially for the monolithic cylinder made of a hypereutectic Al-Si alloy, so-called DiASil®. The newly developed resin was designed to be cured at a relatively low temperature considering over-aging of a piston and confirmed that it exhibited a lower friction coefficient compared to an existing resin coating. Furthermore, pistons of which skirts had various depth and pitch of grooves filled with the resin coating were offered to evaluate wear and seizure characteristics. The results showed deeper grooves on piston skirts were remarkably effective to delay a seizure. All the seizures were triggered when the ratio of Al substrate exposed to the sliding surface reached up to 60-80%, which implied it can be the empirical criteria for a seizure. Therefore, it can be considered the seizure does not occur as long as adequate resin coating remained in the grooves. Finally, influential factors for the seizure and printability of deep grooves were discussed.