Wear of plasma-nitrided aluminum alloys

Low weight and long life-time are necessary requirements for automobiles to significantly reduce CO2 emission and environmental burdens in their use. Aluminum alloys are one of the most promising materials selections for automotive power-train parts and electrical components to reduce their weight and to increase their specific strength. Reliable protective layers for these aluminum parts are indispensable to improve the wear resistance and to reduce the friction coefficient. Among several methods, the precipitate-accommodated plasma nitriding is proposed as a new surface treatment of aluminum alloy parts to significantly increase the aluminum nitride formation rate and to control the nitrided layer thickness. Microstructure characterization and hardness profile measurement are carried out to describe the formation of uniform nitrided layer. Pin-on-disc method is used for dry wearing test to prove that wear volumes as well as friction coefficients are reduced by this AlN protective layer. Low flash temperature and low specific wear volume prove that the present nitriding process is one of the most promising surface treatments for aluminum alloy parts in dry wearing conditions.