Novel nanocomposites for piston self-lubrication
Smooth piston motion is critical to the functioning of diesel engines. The piston moves down to enable intake of air and then up again to compress the air. When fuel is injected and the heat of the compressed air ignites the mixture under pressure, an explosion occurs pushing the piston down again with great force. The piston moves up again to push out the exhaust. This continuous cycling requires smooth movement of parts and thus lubrication to reduce friction, enhance efficiency and decrease emissions. The ‘Nanocomposites for piston/liner systems’ (Napilis) project was initiated to develop new materials and methods to obtain bi-phase (two-phase) nanocomposite materials consisting of a matrix interspersed with self-lubricating nanoparticles to significantly reduce engine friction related to piston motion. Given issues with coating optimisation in the initial phases of work, the researchers focused on coated rings rather than liners for the remainder of the project. Self-lubricating metal and ceramic matrix nanocomposites (SLMCMNCs) have to date never been synthesised because methods used to produce similar microcomposites would be hazardous to workers exposed to nanoparticle powders and other conventional techniques have failed to produce bi-phase materials. The researchers developed novel multiphase and multifunctional coatings for decreased oil consumption, friction and wear. They then developed a new processing method enabling synthesis of bi-phase materials on the nanoscale. Engine tests demonstrated improved engine performance, decreased friction and enhanced scuffing resistance. The team scaled-up the prototype production equipment which was successfully implemented at partner sites with large industrial scale machines. Finally, the investigators developed a detailed economic assessment model facilitating determination of coating cost per piece validating the ability to achieve cost goals. In summary, the Napilis project produced the first instance of SLMCMNC synthesis, employed them in ring coatings for pistons and demonstrated the industrial process capability on site. Commercialisation of the materials and methods and their subsequent use in diesel engines could significantly reduce fuel consumption and emissions while enhancing European competitiveness in numerous related fields.
