Wear and Friction of PTFE and PEEK Coated Cast Iron Piston Ring

In general, around 30% out of total energy of engine is lost because of the friction among piston ring and cylinder liner due to their constant rubbing motion. A piston that reciprocates at high speeds has piston rings that constantly scrape against the wall leading to high frictional losses within the engine. The engine has to work against this resistance to deliver the required power, and hence it will consume more fuel. For this reason, material used for these components is more crucial. Reduction of surface friction between moving parts in order to upturn overall efficiency which can be attained by suitable coating. The most frequently used piston rings are covered with chromium layers that are electro-plated which is being replaced by chrome plating. Low coefficient of friction (COF) and remarkable wear resistance can be achieved by self-lubricating coating of PTFE and PEEK polymer-based composite coatings. Experimental results revealed that the PEEK and PTFE coating performed better in terms of friction and wear, related to the other chrome-plated coatings. Such polymeric-based coatings are inexpensive and offer significant tribological improvements which are viable material systems for piston rings.