Surface Modification of Ti600 Alloy with CrN/NbN Coatings: An Experimental Study

The surfaces of Ti600 alloy,an advanced material for internal combustion engine,were modified with CrN/NbN coatings deposited by high power impulse magnetron sputtering(HiPMS).The influence of the voltage and duty-cycle on the microstructures and tribological behavior was investigated.The results show that the voltage and duty-cycle has a major impact.To be specific,the columnar-phased grains dominated,and as the voltage and duty-cycle increased,the thickness,compactness,hardness,and elastic modulus of the CrN/NbN coatings increased; deposited at 400 V and a duty-cycle of 10 μs,the coatings with strong interfacial adhesion had the max-thickness of 12 μm,max-hardness of 35.6 GPa,max-elastic modulus of 31.7 GPa.The residual stress decreased(changed in a decrease-increase mode) with an increase of duty-cycle(the voltage),the indentation produced ring-shaped cracks at the edges on the coatings,synthesized at a voltage higher than 400 V and a duty-cycle longer than10 μs.