Abstract: The nano -indentation and friction / wear properties of CN film in CN / SIC / Ti ( carbon nitride / silicon carbon / ti ) multilayer thin films ( SIC , Ti films as interlayer ) deposited on Mg alloy ( AZ91D ) substrate using magnetron sputtering technique at room temperature were investigated The results showed that the CN film exhibited a low nano -hardness ( 6.67 GPa ) and Young ' 5 modulus ( 54.68 GPa ) but a high ratio of hardness to modulus ( 0.122 ) When sliding against a Si3N4 ( silicon nitride ) ball using ball -on -disc friction and wear tester underd dry sliding condition , the CN film exhibited good friction / wear properties , 1 e friction coefficient was about 0.162 and the special wear rate was in the order of magnitude 10-6 mm 3 / ( m ? N ) without film Cracking and delamination at interface after long sliding duration ( 3 .5h ) It is believed that tribochemistry and high hardness -to -modulus ratio played key roles in friction reduction and wear resistance