Tribological behavior of molybdenum alloying layer on Ti6Al4V by double glow discharge technique

Molybdenum surface alloying layer was prepared on Ti6Al4V substrate using the double glow discharge technique. The tribological behavior of the resulting surface-modified layer under dry and oil lubrication sliding against SAE52100 steel was evaluated on a ball-on-disc test rig. The results showed that the surface-modified alloying layer was composed of the Mo-deposited layer of 10 μm thick and the Mo-defused layer of 15 μm thick. The hardness and the elastic modulus of the surface-modified layer were 10.859 GPa and 278.839 GPa, which were much larger than those of the Ti6Al4V substrate. The Ti6Al4V substrate was characterized by adhesion wear and scuffing under the dry and lubrication sliding against the steel, while the surface-modified layer experienced much abated adhesion wear and scuffing under the same testing condition. This could be attributed to different hardnesses and elastic moduli, and different microstructures of the Ti6Al4V substrate and its modified counterpart. The surface-modified layer showed poor friction-reducing and fair antiwear ability in the dry sliding against the steel, while it had much better friction-reducing and antiwear ability in the oil-lubrication sliding against the steel.