Coated Piston Ring to Prevent Piston's Aluminum Sticking
In recent high speed gasoline engines, piston's aluminum sticking to compresson rings has been an important issue for engine performance.
To investigate the mechanism of aluminum sticking and evaluate sticking characteristics of piston/ring material and surface coatings, an aluminum sticking rig tester was developed and applied to duplicate the sticking phenomenon. Engine tests were also carried out based upon the result of rig test and the aluminum layer stuck to ring side face was metallurgically analysed by Electron Probe Micro Analyser.
Among many surface coatings of piston rings including phosphate coatings, chromium plate, iron plate and MoS2 coating, it was demonstrated that MoS2 coating is very effective to prevent aluminum sticking at engine break in.