Friction-beating Engine Coating
2014 R&D 100 Winner
Efforts to reduce carbon dioxide emissions will factor heavily into engine development by OEMs, and this will be accomplished in large part from the reduction of internal friction. Daimler AG has made a significant advance in this area with the introduction of NANOSLIDE, an innovative coating for cylinder running surfaces of combustion engines to reduce CO2 emissions, which allows for the use of lighter crankshafts and reduces friction losses in the piston assembly. A new twin wire arc spraying (TWAS) process was invented to coat cylinder running surfaces with coating layers just 0.1 mm thick. Two consumable steel wires are fed into a rotating torch, where an electric arc melts wire within nitrogen, accelerating liquid metal directly to the cylinder wall. These droplets solidify into a nanocrystalline lamellar layer, which is then honed. The finished surface reduces friction by 50%, retaining open pores for oil retention. The new coating displaces heavy cast iron liners in current aluminum crankcases, bringing about a carbon dioxide reduction of 3% for a single engine.
The NANOSLIDE Development Team from Daimler AG
Thomas Behr, Principal Developer, Daimler AG
Bernd Zapf, Principal Developer, Gebr. Heller Maschinenfabrik GmbH