High temperature plasma nitriding to modify Ti coated C17200 Cu surface: Microstructure and tribological properties.

In this work, we studied the microstructure formation and mechanical properties of the Ti alloyed C17200 Cu surface produced by plasma nitriding at 750 °C. The results firstly show that the multiphase coating consists of amorphous and nano-crystalline phases, and various types of Cu-Ti intermetallics, including CuTi 2 , CuTi, Cu 3 Ti 2 , Be 3 Ti 2 Cu, Cu 2 Ti, Cu 3 Ti, formed after the plasma nitriding at 750 °C. The formation of the specific type of Cu-Ti intermetallic depends on the processing duration, where a longer duration contributes to the formation of intermetallics with a higher Cu/Ti ratio. The evolution of the phase compositions is responsible for the change in the mechanical properties. The surface hardness of the modified C17200 Cu alloy improves to be 400 HV 0.01 to a depth of 15 μm after plasma nitriding for 6 h, which contributes to a higher surface tribological resistance with a friction coefficient of 0.3 and a wear rate of 4.15 × 10 −9 g/(r·N) for the modified suface. [ABSTRACT FROM AUTHOR]