Mechanical properties and tribological behaviour of Mo-N coatings deposited via high power impulse magnetron sputtering on temperature sensitive substrates

Hard coatings represent a suitable resource to protect structural materials against oxidation and wear phenomena. Physical Vapour Deposition techniques usually require elevated deposition temperatures to accomplish desired performance, becoming incompatible with sensitive substrates. High Power Impulse Magnetron Sputtering technology allowed obtaining high quality 8 ?m Mo-N coatings at low temperature on a commercial Al-Si alloy. Produced films exhibited good adhesion, noteworthy mechanical characteristics (Hardness >= 22 GPa, Modulus >= 300 GPa) and notable tribological properties. Indeed, they could withstand over 33000 revolutions in dry conditions (track radius 26.5 mm, sliding speed 1.25 m/s, initial Hertzian contact pressure 1 GPa) without evident damage, while the substrate could not overcome a few dozen revolutions in the same operating conditions.