Friction and wear behavior of electroless Ni-based CNT composite coatings

Ni-based carbon nanotube (CNT) composite coatings with different volume fraction (from 5 to 12 vol.%) of CNTs were deposited on medium carbon steel substrates by electroless plating. The friction and wear behavior of the composite coatings were investigated using a pin-on-disk wear tester under unlubricated condition. Friction and wear tests were conducted at a sliding speed of 0.0623 m s−1 and at an applied load of 20 N. The experimental results indicated that the friction coefficient of the composite coatings decreased with increasing the volume fraction of CNTs due to self-lubrication and unique topological structure of CNTs. Within the range of volume fraction of CNTs from 0 to 11.2%, the wear rate of the composite coatings showed a steadily decreasing trend with increasing volume fraction of CNTs. Because of the conglomeration of CNTs in the matrix, however, the wear rate of the composite coatings increased with further increasing the volume fraction of CNTs.